Techniques for localized hydrogen charging using hydrogen plasma focused ion beams

Abstract

Systems, components, methods, algorithms encoded in media, and techniques for localized hydrogen charging of a sample are described. A method of processing a workpiece in a focused ion beam system can include generating a plasma in an ion source gas comprising hydrogen. The method can include extracting a beam of hydrogen ions from the plasma. The method can include directing the beam toward a region of a workpiece, in accordance with a scan pattern. The method can include charging the region of the workpiece with hydrogen. In some embodiments, the method includes decomposing a hydrogen precursor using a charged particle beam, instead of directly irradiating the workpiece with a hydrogen focused ion beam.

Description

TECHNIQUES FOR LOCALIZED HYDROGEN CHARGING USING HYDROGEN PLASMA FOCUSED ION BEAMSCROSS REFERENCE TO RELATED APPLICATION

[0001] The present application claims priority to the earlier-filed United States Provisional Patent Application number US63 / 712,253, entitled, “ METHOD FOR STUDYING HYDROGEN EMBRITTLEMENT USING HYDROGEN PLASMA FOCUSED ION BEAM INSTRUMENTS ” and filed on October 25, 2024, the contents of which are hereby incorporated by reference, in their entirety.TECHNICAL FIELD

[0002] Embodiments of the present disclosure are directed to charged particle beam systems, as well as algorithms and methods for their operation. In particular, some embodiments are directed toward techniques for processing samples using hydrogen-ion and mixed-ion beams.BACKGROUND

[0003] Metals and other materials are susceptible to hydrogen embrittlement, blistering, hydride formation, and degradation of mechanical integrity. These effects can severely limit the reliability of critical components in fields including aerospace, nuclear energy, hydrogen storage, and advanced manufacturing. The mechanisms governing localized hydrogen uptake and its influence on microstructure, fracture behavior, and surface chemistry remain of significant interest. Conventional hydrogen-charging methods, such as electrochemical charging or high-pressure exposure, are volumetric techniques, offering limited spatial localization and can alter the global environment of the sample, making it difficult to study hydrogen-induced effects at specific regions or microstructural features, such as individual grain boundaries.

[0004] In addition to challenges associated with hydrogen embrittlement, there is a broader need for tools that can precisely manipulate and analyze surface chemistry and material transformations at the micro- and nanoscale. Understanding localized reactions, such as oxidation, reduction, or catalytic behavior, requires experimental control over ion delivery, energy deposition, and chemical environment. Conventional approaches lack the ability to confine reactive species to small, well-defined surface areas or to modulate surface chemistryand chemical energy in real time. This limitation hinders the study of heterogeneous materials, thin films, and engineered surfaces that exhibit site-dependent chemical behavior.

[0005] Focused ion beam (FIB) systems and related charged-particle-beam instruments are widely used for microfabrication, sample preparation, and analysis. However, traditional systems typically employ inert ion sources, such as gallium or xenon, and are not designed for controlled delivery of reactive species like hydrogen. Moreover, when multiple ionic species are present, conventional systems lack mechanisms to distinguish or separate the contributions of individual ions to a surface process. As a result, existing tools provide limited capability for localized chemical modification, species-selective processing, or in-situ correlation between hydrogen exposure and its mechanical or chemical consequences. These deficiencies restrict the ability to conduct high-resolution studies of hydrogen behavior, microstructural evolution, and related surface phenomena using charged-particle-based techniques.BRIEF SUMMARY

[0006] In a first aspect, a method includes processing a workpiece in a focused ion beam system. The method can include generating a plasma in an ion source gas that can include hydrogen, extracting a beam of hydrogen ions from the plasma, directing the beam toward a region of the workpiece in accordance with a scan pattern, and charging that region of the workpiece with hydrogen. The plasma can be generated by inductively coupling an electromagnetic field into the ion source gas using a radio-frequency power supply. In some embodiments, the plasma can be generated by coupling from about 100 watts to about 400 watts of radio-frequency power into the plasma.

[0007] In some embodiments, the beam of hydrogen ions includes multiple ionic species of hydrogen, such as monatomic and polyatomic hydrogen ions. The beam can be directed through a magnetic field oriented relative to a beam axis of the focused ion beam system to spatially disperse the ions over a surface of the workpiece. In this way, the system can deliver a substantially isolated ionic species of hydrogen to a localized region of the workpiece for spatially resolved hydrogen charging.

[0008] In some embodiments, a hydrogen barrier layer can be formed over at least a portion of the surface of the workpiece prior to generating the plasma using a second plasma. The swcond plasma used to form the barrier layer can be generated from a second ion source gas, different from the hydrogen source gas, and a second beam of ions can be extracted and directed towardthe surface to form a nitride, oxide, or other hydrogen-impermeable layer. In certain embodiments, the second gas can include nitrogen, oxygen, or a rare gas, and the barrier can be formed in the presence of a precursor such as tetraethyl orthosilicate and / or water vapor. The barrier can be patterned to define a mask that enables selective hydrogen charging through predetermined regions of the surface.

[0009] In a second aspect, a method includes positioning a sample having an elongate protrusion formed therefrom, where the protrusion includes a hydrogen-charged region. The method can include applying a force against the elongate protrusion in accordance with a predetermined parameter, removing the force, obtaining an image of at least the hydrogen-charged portion after the force has been removed, and measuring a displacement parameter based on the image. The charged particle system can include a focused ion beam device and a scanning electron microscope, enabling both beam-based hydrogen implantation and in-situ imaging. The elongate protrusion can have a substantially planar, cantilevered geometry, and the applied force can be delivered by a micromanipulation needle or other probe. These operations can allow quantitative assessment of hydrogen embrittlement or related mechanical effects.

[0010] In some embodiments, the method can include forming the elongate protrusion by focused ion beam milling or alternatively charging a preformed portion of the sample with hydrogen prior to mechanical testing. Imaging can include acquiring a first image before and a second image after force application to determine displacement, deflection angle, or hysteresis, from which mechanical properties such as Young’s modulus or yield strength can be determined.

[0011] In a third aspect, a method can include identifying a target location on a sample at which a chemical reduction is to be performed, computing irradiation parameters to be used for the reduction, using the parameters to generate reducing ions, and delivering the ions to the target location. The irradiation parameters can define a reducing ion beam, such as a hydrogen or ammonia ion beam, directed to chemically reduce a selected region of the sample. In some embodiments, the method includes introducing a reducing precursor to the target location and irradiating the precursor with a charged particle beam, such as a gallium or xenon ion beam, to generate reducing ions in situ. The process can optionally include heating the sample to promote the reduction reaction or to restore metallic or catalytic activity at the target location.

[0012] In an aspect, a focused ion beam system can include one or more charged particle beam sources and control circuitry in communication with one or more machine-readable media storing executable instructions for performing operations of the methods of the preceding aspects in one or more embodiments. The operations can include identifying a target location on a sample, computing irradiation parameters, generating reducing ions based on those parameters, and delivering ions to the target location. Referring to the third aspect, the reducing ions can be delivered to modify surface chemistry, increase purity or conductivity, restore catalytic activity, or control etching rates relative to surrounding regions. These systems and methods can collectively enable localized hydrogen charging, micromechanical testing, and chemical modification of materials within a single charged-particle-beam platform, improving spatial precision, process control, and analytical throughput.

[0013] In another aspect, one or more machine-readable media store executable instructions for performing operations of the methods of the preceding aspects in one or more embodiments. The instructions can be configured for one or more charged particle beam systems employing hydrogen-focused ion beam sources and / or hydrogen precursor sources.

[0014] The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the claimed subject matter. Thus, it should be understood that although the present claimed subject matter has been specifically disclosed by embodiments and optional features, modification and variation of the concepts herein disclosed can be resorted to by those skilled in the art, and that such modifications and variations are considered to be within the scope of this disclosure as defined by the appended claims. For example, the preceding aspects and various embodiments can be combined with one or more other aspects and / or embodiments of the same or other aspects.BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0015] The foregoing aspects and many of the attendant advantages of the present disclosure will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings.

[0016] FIG. 1 is a schematic diagram illustrating an example dual-beam system, in accordance with some embodiments of the present disclosure.

[0017] FIGs. 2A-2B are schematic diagrams illustrating an example plasma focused ion beam (PFIB) system, in accordance with some embodiments of the present disclosure.

[0018] FIGs. 3A-3C are schematic diagrams illustrating an example system for dispersing a beam of ions, in accordance with some embodiments of the present disclosure.

[0019] FIG. 4 is a block flow diagram illustrating example processing workflows involving H+, in accordance with some embodiments of the present disclosure.

[0020] FIGs. 5A-5C are schematic diagrams illustrating techniques for simultaneous patterning, in accordance with some embodiments of the present disclosure.

[0021] FIGs. 6A-6B are schematic diagrams illustrating details of the simultaneous patterning technique of FIGs. 5A-5C, in accordance with some embodiments of the present disclosure.

[0022] FIG. 7 is a graph illustrating example data generated using a Faraday cup and describing the composition of a mixed-species ion beam, in accordance with some embodiments of the present disclosure.

[0023] FIG. 8 is a composite diagram illustrating an example surface processed using the mixed-species ion beam of FIG. 10 under a simultaneous patterning approach described in FIGs. 5A-6B, in accordance with some embodiments of the present disclosure.

[0024] FIGs. 9-10 are electron microscope images illustrating a FIB scan pattern and a resulting simultaneously patterned surface prepared using the beam of FIG. 10, respectively, in accordance with some embodiments of the present disclosure.

[0025] FIGs. 11-13 are composite diagrams illustrating near-surface regions of the patterned surface of FIGs. 9-10 for different ions of the beam of FIG. 7, in accordance with some embodiments of the present disclosure.

[0026] FIG. 14 is a composite diagram illustrating a titanium surface processed using the mixed-species ion beam of FIG. 10 under a simultaneous patterning approach described in FIGs. 5A-6B, in accordance with some embodiments of the present disclosure.

[0027] FIG. 15 is an electron microscope image showing formation of titanium-hydrides, in accordance with some embodiments of the present disclosure.

[0028] FIGs. 16A-16B are composite diagrams illustrating a sample surface treated using an undispersed xenon beam in the presence of a hydrogen precursor near the surface of a titanium sample, in accordance with some embodiments of the present disclosure.

[0029] FIGs. 17A-17B are composite diagrams illustrating a sample surface treated using an undispersed hydrogen beam, in accordance with some embodiments of the present disclosure.

[0030] FIG. 18 is a composite diagram illustrating a sample surface that has been patterned using a first FIB treatment to mask portions of the surface and a second FIB treatment to irradiate the surface with hydrogen ions, in accordance with some embodiments of the present disclosure.

[0031] FIG. 19 is a composite diagram illustrating a section of the sample of FIG. 18 including a near-surface region, in accordance with some embodiments of the present disclosure.

[0032] FIG. 20 is an electron microscope image depicting a cantilevered section of a sample formed by a preliminary FIB treatment, in accordance with some embodiments of the present disclosure.

[0033] FIG. 21 is a composite diagram including a FIB scan pattern superimposed on the section of the sample depicted in FIG. 20, in accordance with some embodiments of the present disclosure.

[0034] FIG. 22 is an electron microscope image depicting the resulting surface of the section of FIG. 20 following the treatment depicted in FIG. 21, in accordance with some embodiments of the present disclosure.

[0035] FIGs. 23A-23D are electron microscope images illustrating an example sequence making up a micromechanical test of a cantilevered section, in accordance with some embodiments of the present disclosure.

[0036] FIGs. 24A-24B are schematic diagrams illustrating an in-situ force sensor adapted for use in the micromechanical test of FIGs. 23A-23D, in accordance with some embodiments of the present disclosure.

[0037] FIG. 25 is a block flow diagram of an example process for micromechanical testing of a section of a sample, in accordance with some embodiments of the present disclosure.

[0038] FIG. 26 is a composite diagram depicting a sample surface following oxidation by a dispersed beam of oxygen ions, in accordance with some embodiments of the present disclosure.

[0039] FIG. 27 is a composite diagram illustrating an elemental mapping of the sample surface of FIG. 26, in accordance with some embodiments of the present disclosure.

[0040] FIG. 28 is a composite diagram depicting the sample surface of FIG. 26 following spatially localized reduction by a dispersed beam of hydrogen ions, in accordance with some embodiments of the present disclosure.

[0041] FIG. 29 is a composite diagram illustrating an elemental mapping of the sample surface of FIG. 28, in accordance with some embodiments of the present disclosure.

[0042] FIG. 30 is a composite diagram depicting the sample surface of FIG. 28 following a second spatially localized reduction by a dispersed beam of hydrogen ions at a lower beam energy, in accordance with some embodiments of the present disclosure.

[0043] FIG. 31 is a composite diagram illustrating an elemental mapping of the sample surface of FIG. 30, in accordance with some embodiments of the present disclosure.

[0044] FIG. 32 is a block flow diagram of an example process for spatially localized reduction of a sample, in accordance with some embodiments of the present disclosure.

[0045] In the drawings, like reference numerals refer to like parts throughout the various views unless otherwise specified. Not all instances of an element are necessarily labeled to reduce clutter in the drawings where appropriate. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles being described.DETAILED DESCRIPTION

[0046] While specific embodiments have been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the disclosure. In the forthcoming paragraphs, embodiments of charged particle beam systems, components, and methods for processing samples using a beam of ions are described. In the interest of simplicity of description, embodiments of the present disclosure focus on techniques for at least partially dispersing a beam of ions and processing at least a portion of a sample surface using the beam of ions, as applied in focused ion beam (FIB) instruments. To that end, embodiments are not limited to such systems, but rather are contemplated for analytical instrument systems that employ beams of mixed ions, both in terms of elemental composition and / or in terms of mass-to-charge ratio. In an illustrative example, broad-ion-beam systems an employ electromagnetic dispersal techniques of the present disclosure. Similarly, aspects of the present disclosure can be integrated into analytical systems that can derive meaningful information from ions of diverse mass-to-charge ratio, such as single-ion-mass-spectroscopy techniques. While embodiments of the present disclosure focus on dual-beam FIB-SEMsystems, additional and / or alternative systems are contemplated, including but not limited to single-beam FIB systems, triple-beam laser-SEM-FIB systems, or the like.

[0047] Embodiments of the present disclosure include systems, methods, algorithms, and non-transitory media storing computer-readable instructions for processing a sample with hydrogen. Advantageously, techniques of the present disclosure improve ion beam processing of sample surfaces by: i) spatially selective processing of samples by various ionic species present in a beam to introduce hydrogen into the sample; ii) modifying surface chemical properties using hydrogen in accordance with deflection patterns; and iii) controlling and / or modulating diverse surface chemical reactions by modifying the relative order of exposure to specific ions making up a hydrogen-containing FIB beam. To that end, the techniques presented here represent a significant advancement in the breadth of application, flexibility, and precision with which ion beam processing can be employed.

[0048] FIG. 1 is a schematic diagram illustrating an example dual-beam system 100, in accordance with some embodiments of the present disclosure. The example system 100 includes an electron source 105, an electron beam column 107, an ion source 110, a focused ion beam ("FIB") column 111, a gas injection system ("GIS") 115, a vacuum chamber 120, and a sample stage 125. The electron beam column 107 is illustrated as a Scanning Electron Microscope (SEM) column, such that the example system 100 corresponds to a dual beam FIB-SEM system. The electron beam column 107, the FIB column 111, and the GIS 115 are illustrated as being operably coupled with the vacuum chamber 120, with the electron beam column 107 defining a first beam axis A and the FIB column 111 defining a second beam axis B. The axes A and B are illustrated converging onto a region of a sample 130, with the GIS 115 oriented toward the region of the sample 130 and configured to direct a gas stream including a precursor into the vacuum chamber. Advantageously, while axes A and B can also be oriented toward different locations, convergence permits the SEM system to image the region of the sample being processed by the FIB.

[0049] The electron source 105 can include one or more emitters configured to generate free electrons and to direct the electrons into the electron beam column 107. The emitters can include thermionic emitters, Schottky emitters, field-emission source emitters, or combinations thereof, operably coupled to power systems configured to apply a high-voltage (e.g., on the order of kilovolts to hundreds of kilovolts) to an emission region of the emitter material. For example, the electron source 105 can include a lanthanum hexaboride (LaBe) emitter crystal towhich a high electrical potential is applied to elicit the emission of electrons from a tip of the emitter crystal. In this way, a beam of electrons can be directed into the electron beam column 107.

[0050] The electron beam column 107 includes electromagnetic optics (e.g., electrostatic lenses, electromagnetic lenses, monochromators, aberration correctors, etc.) and apertures configured to shape, focus, defocus, narrow, and / or direct the beam of electrons such that the beam is focused onto the sample 130, in accordance with a set of operating parameters. The operating parameters can include a beam current, a beam energy (e.g., in volts, in electron volts, or the like), a magnification parameter, a scan pattern, a dwell time, and / or one or more pulse parameters. In this way, the example system 100 can function as an SEM to image portions of the sample 130 and / or can be used for e-beam assisted deposition of material onto the sample 130 (e.g., in coordination with the GIS 115) or other sample modifications.

[0051] The ion source 110 can include one or more components configured to generate a beam of ions and to direct the ions into the FIB column 111. In general, the ions can include metal ions and / or nonmetal ions (e.g., noble gas, halogen, oxygen, nitrogen, or the like). To that end, the ion source 110 can include a plasma source (e.g., an inductively coupled plasma source or a microplasma source of the present disclosure) and / or a metal ion source (e.g.. a liquid-metal ion source). In the context of the present disclosure, atomic and / or molecular gases and their mixtures can serve as plasma precursor gases, from which a stream of ions can be extracted. To that end, embodiments of the present disclosure are directed at systems, components, and methods for igniting and sustaining plasma discharges, and can include associated techniques for extracting ions from the plasma discharges, as described in more detail in reference to FIGs. 2A-2B.

[0052] As with the electron beam column 107, the FIB column 111 can include electromagnetic optics (e.g., electrostatic lenses, electromagnetic lenses, monochromators, etc.) and apertures configured to shape, focus, defocus, narrow, and / or direct the beam of ions such that the beam is focused onto the sample 130. in accordance with a set of operating parameters. The operating parameters can include a beam current, a beam energy (e.g., in volts, in electron volts, or the like), a magnification parameter, a scan pattern, a dwell time, and / or one or more pulse parameters. In this way, the example system 100 can function as a FIB to modify portions of the sample 130 and / or to be used for ion-beam assisted removal of material from and / or deposition of material onto the sample 130 (e.g., in coordination with the GIS 115). The GIS115 can also be used to deliver hydrogen precursors (e.g., water vapor, hydrocarbons, etc.) to the vicinity of a sample, as described in more detail in reference to FIG. 32.

[0053] Analogous to the energies described in reference to the electron beam, above, the ion beam energy can be selected (e.g., by a user, by an algorithm initiated by a user, and / or automatically without user intervention). In some embodiments, additional and / or alternative precursor decomposition mechanisms (e.g., surface activation and / or secondary electron reemission) can be used as a mechanism for precursor decomposition, thereby allowing the ion beam energy to be determined based at least in part on a relationship between beam energy, sample material properties, and the energetic characteristics of the precursor deposition reaction mechanism. Advantageously, ion beam-induced deposition can elicit relatively high yields, in comparison to electron beam-induced deposition, based at least in part on the combined effect of multiple energy transfer pathways.

[0054] The GIS 115 includes constituent elements that together permit the GIS 115 to generate a gas stream including the precursor and to direct the gas stream into the vacuum chamber. The components of the GIS 115 can include a carrier gas inlet, a nozzle 119, and a conduit fluidically coupling the nozzle 119 and a precursor reservoir 117. The precursor reservoir 117 can include a substantially non-reactive container (e.g., a ceramic crucible, fluorinated hydrocarbon (e.g., PTFE) enclosure, a non-reactive metal or alloy, or the like) that is at least partially exposed to the conduit. In this way, vapor generated from a precursor disposed in the precursor reservoir 117 can be directed toward the nozzle and into the vacuum chamber (e.g., by pressure-driven flow induced by a pressure gradient relative to the pressure of the vacuum chamber). In some embodiments, the GIS 115 includes a carrier gas inlet, fluidically coupled with the nozzle 119 via the conduit. In this way, the precursor can be entrained in a flow of carrier gas and directed toward the nozzle and into the vacuum chamber. Additionally and / or alternatively, the precursor can include a gas at standard conditions and can be introduced to the GIS 115 via a gas inlet provided as part of the GIS 115.

[0055] The operation of one or more components of the example system 100 can be coordinated by control circuitry, in accordance with machine-executable instructions (e.g., software, firmware, etc.) that can be stored in machine-readable storage media and / or received from external systems via wired and / or wireless communication techniques (e.g., over a WiFi or Bluetooth link). To that end, components of the example system 100 can be automated (e.g., operating without human intervention), pseudo-automated (e.g., operating with limited humanintervention to initiate operations, analyze output and confirm, or the like), or manually operated (e.g., where individual operations of the example system 100 are performed and / or coordinated by a human user). In an illustrative example, the sample stage 125 can be mechanically coupled with automated stage controls 127 that permit the sample 130 to be reversibly tilted relative to the beam axes A and B, such that the surface of the sample is oriented at a particular angle relative to a given beam axis during operation of the corresponding charged particle beam source. In this way, the operation of a given beam source can be coordinated with the operation of the stage controls 127. In another example, detectors provided as part of the example system 100 can be integrated into a control system that is configured to manipulate one or more operating parameters of the ion source 110, as part of a control scheme to implement one or more of the processing techniques described in reference to FIGs., 2-32 of the present disclosure.

[0056] Some embodiments of the present disclosure omit one or more components of example system 100. For example, one or more of the sources 105 and 110 and / or columns 107 and 111 can be omitted. In an illustrative example, an single-beam FIB system can be configured to perform operations for generating a beam of ions. Similarly, a multi-beam FIB system other than a dual-beam FIB-SEM (e.g., a FIB-Laser system or a FIB-SEM system for which two or more beam axes are not convergently trained on a given region of the sample 130) can implement the the charged particle processing techniques of the present disclosure.

[0057] FIGs. 2A-2B are schematic diagrams illustrating an example plasma focused ion beam (PFIB) system 200, in accordance with some embodiments of the present disclosure. The PFIB system 200 is an example of the focused ion beam source described in reference to system 100 of FIG. 1. PFIB system 200 includes an ion source 205, an ion column 210, a vacuum system 215, and electronic components 220 configured to control the optics of the column 210 and / or the ion source 205. The system 200 further includes power circuitry 225 and gas supply system(s) 230, coupled with the ion source 205 and / or column 210. The system 200 is configured to generate a beam of ions and direct the beam of ions towards a workpiece 235, in substantial alignment with a beam axis “B,” and in accordance with a mill pattern.

[0058] As described in more detail in reference to the forthcoming figures, the ion source 205 can generate the beam of ions by extracting ions from a discharge formed using one or more gases supplied from the gas supply system(s) 230. As illustrated in FIG. 2B, the ion source 205 is coupled with the gas supply system(s) 230 via one or more gas conduits 240. The gasconduit(s) 240 introduce gases to a discharge chamber 245 that defines an internal volume within which a discharge 250 can be generated. In the context of FIGs. 2A-2B, the ion source 205 is illustrated as an inductively coupled plasma (ICP) source, for which the discharge chamber 245 can be formed from a dielectric or insulating material around which a helical electrode 255 is disposed. A radio-frequency (RF) power signal can be provided by the power circuitry 225 to at least partially ionize the gas in the discharge chamber 245. Ions 260 from the discharge 250 can be extracted from the discharge chamber, and directed toward the ion column 210, by accelerating fields applied by one or more electrodes 265 (e.g., source electrode and / or extractor electrode).

[0059] Advantageously, the system 200 is configured to generate the discharge 250 from a combination of gases, including hydrogen. In some cases, more than two gases are provided to the discharge chamber 245. In this way, the ions 260 extracted from the discharge 250 can include a mixture of ionic species that can be formed from the gases provided by the gas supply system(s) 230. As described in more detail in reference to FIGs. 3A-32, the composition of the ions 260 can include at least a fraction of a relatively reactive ionic species, such as hydrogen, oxygen, nitrogen, combinations thereof, or the like, and a fraction of a relatively inert gas, such as argon, krypton, xenon, or the like.

[0060] FIGs. 3A-3C are schematic diagrams illustrating an example technique for dispersing a beam of ions, in accordance with some embodiments of the present disclosure. FIG. 3A illustrates the interaction of a beam of ions including different ionic species with an electromagnetic field generated by an objective lens assembly of the electron beam column. FIG. 3B illustrates the transit of the beam of ions through the electromagnetic field in more detail, with the dispersal of the beam of ions shown schematically. FIG. 3C illustrates one physical explanation to better understand the operation of the technique of FIGs. 3A-3B.

[0061] FIG. 3 A illustrates a portion of the example system 100 of FIG. 1, enlarging the region of the sample 125, disposed in the vacuum chamber 110, in the interest of highlighting the role of the various components of the example system 100 in processes of the current disclosure, as described in more detail in reference to FIGs. 4-32. For the technique illustrated in FIG. 3A, components of the electron optical objective 300 in the SEM column 105 are used to generate a magnetic field 305 in a vicinity of the sample 125. This can be referred to as an immersion field when used for imaging using the electron beam. The schematic diagram in FIG. 3A is not drawn to scale, but reflects that the magnetic field can extend over a portion of the sample 125or can extend over the entire sample, based at least in part on the operating parameters of the objective 300. In an illustrative example, the lens coil 301 of the objective 300 can be operated to generate a field strength characterized by an operating parameter from about -50 Ampere-Turns (AT) to about 300 AT in the vicinity of the sample, including sub-ranges, fractions, and interpolations thereof, as described in reference to the experimental data presented in FIGs. 21-24 (e.g., about -10 AT to about 50 AT). It is understood that the magnitude of the magnetic field can vary along the length of the beam axis A, such that the magnetic field can be stronger within the objective 300 or can be stronger between the objective 300 and the sample 125.

[0062] As described in more detail in reference to FIGs. 2A-2B, and in reference to forthcoming figures, a method for processing a sample can include extracting a beam of ions 310 from a mixture of a first gas and a second gas (e.g., beam of ions 260 of FIG. 2B). In some cases, the first gas is a relatively heavy gas and the second gas is a relatively light gas, such that the beam 310 includes relatively heavy ions of the first gas and relatively light ions of the second gas. In the examples described in reference to FIGs. 7-15D, the relatively heavy gas is an relatively inert gas (e.g., xenon, argon, krypton, etc.) and the relatively light gas is a relatively reactive gas (e.g., hydrogen, oxygen, nitrogen, or the like). The beam of ions 310 extracted from the plasma source (e.g., source 105 of FIG. 1, source 205 of FIGs. 2A-2B) can include a mixture of ions of the first gas and ions of the second gas, but can also include multiple ionic species of one or more of the gases included as ion source gases. In the data described in reference to FIG. 7, for example, monatomic and polyatomic ions of hydrogen are observed.

[0063] Methods of the present disclosure can include deflecting the beam of ions 310 in accordance with a deflection pattern. The deflection pattern refers to an encoded set of steering instructions that can be provided as one or more voltage signals to a set of electrostatic deflectors 330 (e.g., deflector coils, plates, or the like). The deflection pattern causes the beam of ions 310 to traverse at least a portion of a surface (e.g., the sample 125 of FIG. 1, the workpiece 235 of FIG. 2A) in accordance with a specified irradiation scheme, including information for the direction of travel of the beam (e.g., a raster pattern, a point-spread pattern, or the like), as well as information for the duration of irradiation (e.g., dwell time, number of exposures, or the like).

[0064] The beam of ions 310 can be directed through the magnetic field 305, as illustrated in FIGs. 3A-3C. As illustrated in FIG. 3A and FIG. 3B, the magnetic field 305 can be applied tothe beam of ions 310 between an exit of the charged particle beam column (e.g., FIB column 110 of FIG. 1) and the sample surface 325. In the vicinity of the sample 125, the magnetic field can be oriented in a direction that is oblique relative to an axis of the beam 310 (labeled B, in FIG. 3A, but not referring to the alignment of the magnetic field, which is often denoted “ B ”). In this way, the field 305 can be configured to at least partially disperse the beam in space. As illustrated in FIGs. 3B-3C. dispersal of the beam in space refers to the tendency of a magnetic field to apply a force to a charged particle travelling through it that is a function of the particle's trajectory and the orientation of the field. In this way, ionic species of the beam 310 are deflected by the magnetic field 305 in proportion with the Lorentz force applied to the constituent ions as the beam 310 traverses the field 305. FIGs. 3A-3C focus on magnetic field-induced dispersal, but it is contemplated that electrostatic techniques could produce similar spatial dispersal in some embodiments. For example, an electrostatic field can apply a force that is proportional to the charge of the ions, which can case a deflection that is a function of both mass and charge, which is the operating principle in electrostatic blanking of charged particle beams.

[0065] The magnetic field 305 through which the beam of ions 310 passes causes ions of the first gas and ions of the second gas to separate in space, attributable at least in part to the differences in mass and charge. For example, through a given magnetic field, an ionic species characterized by a relatively high mass-to-charge ratio (m / z) will be deflected less than an ionic species characterized by a relatively low m / z ratio. This causes the beam of ions 310 to process a first portion of the sample surface 325 by the relatively light ions and a second portion of the sample surface by the relatively heavy ions, as described schematically in reference to FIGs. 5A-6B.

[0066] FIG. 4 is a block flow diagram illustrating example processing workflows involving H+, in accordance with some embodiments of the present disclosure. The blocks represent portions of an overall sample analysis workflow including sample prep, hydrogen charging, micromechanical testing, and microanalysis. Each of the blocks include constituent operations that can be implemented using the systems of the present disclosure, including but not limited to the dual-beam FIB-SEM system described in reference to FIGs. 1-3C. The operations described can be performed automatically (e.g., without human involvement or intervention), pseudo-automatically (e.g., with limited human involvement or intervention, such as sample loading or process initiation), and / or manually (e.g., with significant human intervention and / orinvolvement). While the blocks are illustrated as being arranged in a sequence, it is contemplated that operations can be reordered, repeated, omitted, replaced, and performed in sequence or in parallel. In an example, operations for hydrogen charging can precede one or more operations for sample preparation, such as surface analysis, irradiation using ion beam and / or electron beam techniques, and selecting and / or modifying the ion source gas / gas composition.

[0067] As described in more detail in reference to FIGs. 1-3C and FIGs. 18-19. operations for sample preparation can include loading a sample into an analysis and processing chamber (e.g., vacuum chamber 110 of FIG. 1) of a charged particle beam system (e.g., FIB-SEM 100 of FIG.1). Sample loading can also include operations for locating a region of interest (ROI) of the sample, which can be or include a portion of the sample including sub-surface structures, such as integrated circuit devices. Locating the region of interest can include a combination of operations for repositioning the sample and aligning / orienting a beam of charged particles (e.g., a FIB beam). In an illustrative example, a combination of motion instructions can be provided to the stage (e.g., sample stage 125 of FIG. 1), followed by fine orientation within a smaller area on the sample surface.

[0068] Operations for sample preparation can include selecting an ion source gas, to be used in plasma-based FIB, or PFIB, sources, as described in more detail in reference to FIGs. 2A-3C. Examples of source gases include rare gases (e.g., helium, argon, neon, krypton, xenon), elemental gases (e.g., hydrogen, halogens, oxygen, nitrogen, etc.), carbon-source gases (e.g., linear hydrocarbons, polycyclic aromatic hydrocarbons, etc.), and molecular gases (e.g., nitrous oxide, nitric oxide, azides, ammonia, etc.). Discussion of the present disclosure focuses on mixtures of elemental gases and rare gases, of which embodiments including nitrogen, oxygen, hydrogen, and xenon, are explicitly described. It is contemplated, however, that embodiments of the present disclosure include additional and / or alternative compositions of ion source gas.

[0069] As described in more detail in reference to FIGs. 17-20, sample preparation can include one or more operations for irradiating at least a portion of the sample surface using a FIB beam, formed by extracting ions from a discharge ignited in the ion source gas (e.g., discharge 245 of FIG. 2B). Ion-beam sample prep can include sectioning samples, forming lamellae, delayering, slice-and-view, or the like, examples of which are described in more detail in reference to the forthcoming figures. The sample can be analyzed as part of the preparation process, for example, as part of assessing an initial state of a surface, relative to asubsequent treatment under the other sub-processes of an overall material processing and analysis workflow (e.g., prior to implantation charging and microanalysis). In an illustrative example, an elemental mapping can be prepared for a lamella surface (e.g., using energy dispersive techniques) that can improve the assessment of hydrogen charging of at least a portion of the lamella, as described in more detail in reference to FIGs. 19-21. In another example, analysis of the irradiated surface can form a part of an iterative procedure for locating and / or exposing features of interest in the sample (e.g., via a slice-and-view process).Techniques including EBSD can be applied to characterize crystal phase and grain orientations prior to and / or after H+exposure, an example of which is shown in Fig 16B. Advantageously, such comparative microanalyses provide valuable insight, at least in part because some phases, grain orientations, and / or grain boundaries exhibit different behavior towards hydrogen. For embrittlement studies, techniques which can help visualize the location of defects in the sample (e.g., Electron Channeling Contrast Imaging, or “ECCI”) can be used before and after H+exposure. Hydrogen is known to increase defect mobility, which can be detected by ECCI. For studies involving chemical reduction, characterizing the chemical composition of the surface (e.g., using EDS), can demonstrate that H+exposure has induced a chemical reaction in or on the sample .

[0070] Hydrogen charging operations are described in more detail in reference to FIGs. SA-18, and in block flow form in FIG. 24 and FIG. 32. Hydrogen charging, in this context, refers to techniques for introducing hydrogen into a material sample, for which the energy for implantation is provided by a charged particle beam, and the hydrogen can be delivered in various ways. Sub-processes for hydrogen charging include chemical charging and implantation charging, each including respective operations enabling the delivery of hydrogen into the sample matrix, as described in more detail in reference to FIGs. 5A-33. Chemical charging uses the energy of a relatively inert ion beam (e.g., a rare-gas ion beam or argon, krypton, or xenon) or an electron beam to decompose a precursor including hydrogen (e.g., water, hydrocarbon, etc.) that is present in the vicinity of the sample surface. In this way, the chemical charging sub-process can include operations for delivering a hydrogen-containing precursor to the vicinity of the surface of the sample. Without being bound to a particular physical mechanism or phenomenon, a fraction of the hydrogen-containing precursor that adsorbs to the surface of the sample can decompose using the energy of a charged particle beam, causing a portion of liberated hydrogen to diffuse into the matrix of the material.

[0071] Implantation charging, in contrast, involves direct delivery of energetic hydrogen ions (e.g., an H+FIB beam at an energy of about 2 keV) to the surface of the sample, in a focused spot. To that end, operations for implantation charging can include switching the ion source gas to hydrogen, as described in more detail in reference to FIG. 2A, and irradiating the sample in accordance with a deflection pattern, as described in more detail in reference to FIGs. 5A-9.

[0072] As described in more detail in reference to FIGs.19-24, localized hydrogen charging enables highly specific micromechanical testing that is otherwise unavailable with conventional hydrogen charging techniques. To that end, micromechanical testing operations include unidirectional strain and / or loading of a sample, micro-indentation, compression, and / or tensile testing (e.g., pull-testing). Hydrogen charging techniques of the present disclosure enable in-situ testing in a dual-beam system that also offers high-resolution imaging and elemental analysis. In this way, a dual-beam FIB-SEM can be configured with tools for sensitive measurement of modulus, tensile strength, indentation hardness, etc, on a microscopic scale and with a full range of microanalysis techniques that are not typically available without sample transfer between multiple instruments. To that end, microanalysis includes operations for determining the extent of hydrogen charging in a sample, the influence of hydrogen charging on material, chemical and physical properties of the sample, among other aspects, as described in more detail in reference to FIGs. 26-32. Microanalysis can include elemental mapping, imaging, ion sputtering and analysis techniques (e.g., ion-beam based mass-spectrometry) as well as additional ion-beam processing operations for revealing internal sample surfaces and / or features. As part of microanalysis, one or more operations of sample preparation can be repeated to prepare samples that have been previously processed by the hydrogen charging workflow for other techniques. For example, a sample previously subjected to hydrogen charging can be processed by a rare-gas PFIB (e.g., Xe+FIB) to prepare a lamella at least partially including the charged portion of the sample. The lamella can be extracted and analyzed in transmission and / or scanning transmission electron microscopes, for example, to assess the influence of hydrogen charging on lattice defects, lattice strain, or other crystallographic properties.

[0073] FIGs. 5A-5C are schematic diagrams illustrating techniques for simultaneous patterning, in accordance with some embodiments of the present disclosure. To that end, FIGs.5A-5C are not drawn to scale. The diagrams in FIGs. 5A-5C serve to introduce the approaches used to generate example data described in reference to FIGs. 10-21. To that end, FIG. 5Aincludes a schematic showing two spatially separated portions 500 of a sample surface. A first portion 500-1 is irradiated by a first beamlet 505 and a second portion 500-2 is irradiated by a second beamlet 510. In the example of FIG. 5A, the first beamlet 505 is characterized by a relatively high m / z, demonstrated by a relatively short first offset 515 from the beam axis B. The second beamlet 510 is characterized by a relatively low m / z, demonstrated by a relatively long second offset 520 from the beam axis B, assuming a spatially isotropic field being used to disperse the beam of ions into the beamlets 505 and 510. The portions 500 are defined by a deflection pattern 525, represented here as a region of the sample surface of commensurate size to those of portions 500-1 and 500-2, which corresponds to the area of the sample surface over which an undispersed beam 530 would travel in the absence of an electric and / or magnetic dispersal field. In this way, the deflection pattern 525 defines a trajectory 535 for the beamlets 505 and 510 that is substantially reproduced at each respective offset 515 and 520 from the beam axis.

[0074] As described in more detail in reference to FIGs. 5B-6C, spatially separating the portions 500 affords significant flexibility over the order and type of surface processing by ions of the beam of ions. For example, FIG. 5B shows that a beam comprising three different ionic species of different m / z can be separated into three spatially separated portions 500, with a third portion 500-3 interposed between the first portion 500-1 and the deflection pattern 525 at a third offset 540 shorter than the first offset 515. This reflects that the beam of ions can include more than two ionic species, as described in reference to the example of monatomic and polyatomic hydrogen ions in the forthcoming figures that can dissociate into multiple ionic species (e.g., ammonia can dissociate into multiple combinations of nitrogen and hydrogen polyatomic ions). As such, the relatively high m / z ion can be a polyatomic and / or molecular ion, such as diatomic oxygen, diatomic nitrogen, nitric oxide, or larger polyatomic ions, and a relatively inert constituent of the beam of ions (e.g., helium, argon, etc.) can be a lighter ion. For example, the relatively heavy ions can be characterized by an atomic mass of 36 AMU or greater (e.g., krypton, xenon, N2O, etc.), and the relatively light ions can be characterized by an atomic mass smaller than 36 AMU (e.g., argon, H2O, H3, H2, H, O2, N2, O, N, NFU, etc.).

[0075] FIG. 5C illustrates a particular advantage of the techniques of the present disclosure, namely, the spatial localization and chemical control of FIB processing by exposure to multiple dispersed beams, in accordance with different deflection patterns 525. In this way, one or more regions of a sample can be irradiated by at least a subset of the constituent ionic species of thebeam of ions, with the dose, spatial localization, and energy of each ionic species being separately controlled. In the example of FIG. 5C, the second portion 500-2 is partially overlaid by the third portion 500-3 by shifting the deflection pattern 525 by a vector 545 projected onto the surface, including an x component and a y component, such that only part of the second portion 500-2 is overlaid by the third portion 500-3. This example illustrates a relatively simple approach, in that the deflection pattern, beam composition, beam energy, and temporal factors (e.g., dose, dwell time, etc.) are not discussed. It is contemplated, however, that techniques of the present disclosure include processing samples by spatially localized treatment using two or more ionic species, with precise control over the dose, energy, chemical composition, chronological order or sequence of irradiation, without altering the composition of the plasma source gas. Advantageously, these capabilities permit detailed surface studies of diverse materials, of particular relevance in the fields of heterogenous chemistry, nanomaterials, and metallurgy, among others.

[0076] FIGs. 6A-6B are schematic diagrams illustrating details of the simultaneous patterning technique of FIGs. 5A-5C. in accordance with some embodiments of the present disclosure. The two diagrams in FIGs. 6A-6B illustrate additional operating parameters that afford control over the spatial and temporal localization of surface processing by multi-species FIB beams. In particular, the magnitude of the dispersal can be modulated by varying the magnitude of the electric and / or magnetic field (e.g., field 305 of FIG. 3A) in addition to or alternatively to varying the energy of the beam. To that end, the deflection pattern, the magnetic field, and parameters of the beam of ions can be defined such that a dispersal extent of the beam of ions can be a controllable feature of sample processing. The dispersal extent can be expressed as a ratio of overlap in two dimensions, as a ratio of offsets relative to the beam axis. B, in one dimension, and / or as a discrete qualitative scale (e.g., undispersed, partially dispersed, fully dispersed.

[0077] In the example of FIG. 6A, a first portion 600-1 of a sample surface 605 is irradiated by a first beamlet 610-1 and a second portion 600-2 of the sample surface 605 is irradiated by a second beamlet 610-2. The parameters of the system are defined such that the first portion 600-1 and the second portion 600-2 are non-contiguous and non-overlapping, where the first portion 600-1 is separated from the region of the deflection pattern 625 by a first offset 615 and the second portion 600-2 is separated from the deflection pattern 625 by a second offset 620. The fully dispersed configuration illustrated in FIG. 6A is another example of the techniquesdescribed in reference to FIGs. 5A-5C. In contrast, FIG. 6B shows an example technique where the beam is remains fully dispersed, with beamlets being spatially resolved and separate, but where the dimensions of a deflection pattern 635 are defined such that the portions 600 at least partially overlap. In this way, the deflection pattern 635 provides a further source of control over surface treatment. The resulting treatment has three distinct regions, from which the effects of individual ions and combinations of ions on the sample surface 605 can be observed.

[0078] FIG. 7 is a graph illustrating example data generated using a Faraday cup and describing the composition of a mixed-species ion beam, in accordance with some embodiments of the present disclosure. The graph presents “scanned distance” in units of millimeters on the x-axis and current in picoamperes on the y-axis. These are analogous to m / z on the x-axis and for composition on the y-axis, in that the faraday cup is measuring beam composition as a function of offset (e.g., offsets 515 and 520 of FIG. 5 A) by scanning a current detector along a lateral direction. The resulting spectrum reveals that the beam being measured includes five main constituent ions. From the composition of the plasma source gas, as well as spectroscopic examination, it is known that in the particular example of FIG. 7, and as described in reference to the forthcoming figures, the constituent ionic species included in the beam include monatomic and polyatomic hydrogen ions, xenon ions, and molecular water ions, dispersed along a given linear dimension in proportion to their m / z ratios. To that end, the beam axis is positioned to the right of the peak identified as xenon, with the offset increasing with decreasing ionic mass, from xenon, to monatomic hydrogen.

[0079] Notably, ionic species are present in the beam at different relative fractions. For example, the data reflect a relatively high fraction of xenon and monatomic hydrogen, relative to polyatomic hydrogen and water. As described in reference to FIGs. 5A-6B, the techniques of the present disclosure permit samples to be processed with precise control of ion dose, compensating for differences in ion fraction. In this way, controlled study of ion-surface interaction is improved significantly, both by modifying the relative fraction of different ions (e.g., by modulating the plasma parameters of the ion source), and by controlling the dispersal extent and deflection pattern(s) employed. In an illustrative example, the relative proportion of monatomic hydrogen ions to polyatomic hydrogen ions can be controlled by varying the plasma power, with higher plasma power being associated with higher dissociation rates (e.g., shifting the fraction of monatomic hydrogen higher).

[0080] FIG. 8 is a composite diagram illustrating an example surface processed using the mixed-species ion beam of FIG. 7 under a simultaneous patterning approach described in FIGs.5A-6B, in accordance with some embodiments of the present disclosure. The diagram includes a patterned surface, imaged in an SEM micrograph, with the different portions (e.g., portions 500 of FIG. 5A) of the surface labeled with the corresponding ionic species that was directed to each respective portion. Visually reproducing the relative offsets that were quantified in FIG. 7, the surface has been treated by the five different ionic species in five different and noncontiguous regions of the sample surface. Advantageously, this permits the properties of the treated surface to be analyzed using typical techniques (e.g., x-ray mapping), as well as samples to be extracted from one or more portions for further microanalysis (e.g., by sectioning, lamella prep, etc.) to assess the particular effects of individual constituent ions. These techniques are conventionally possible only with switching the composition of the beam of ions (e.g., by changing the plasma source gas).

[0081] FIGs. 9-10 are composite diagrams illustrating a simultaneously patterned surface and a detail of the patterned surface, respectively, the patterning being prepared using the beam of FIG. 7, in accordance with some embodiments of the present disclosure. FIG. 9 includes a secondary electron image of a processed sample surface, taken in a dual-beam FIB -SEM, using the FIB as the source of secondary electrons, as indicated by the system information at the base of the image. The SE image is annotated to identify which of the ionic species of the dispersed beam are associated with which treated regions of the sample surface. As described in reference to FIGs. 5A-5B and FIG. 6A, the sample surface has been simultaneously irradiated in noncontiguous regions by three distinct ionic species of hydrogen (monatomic, diatomic, and triatomic), ionized water, and xenon ions. A scan pattern 900 is indicated in a diagonal fill pattern. The regions corresponding to hydrogen ions are labeled. Advantageously, simultaneous patterning demonstrated in the image of FIG. 9 can deliver a specific dose of one of the constituent ionic species. In the example shown, the treatment was controlled for a specific dose of monatomic hydrogen ions. As reproduced in the image, the FIB treatment used a current of 6.15 nA H+ (as measured using the techniques of FIG. 7), an average beam energy of 30 keV, a treatment region of about 5 um by about 50 um, and for a total treatment time of 5 minutes and 42 seconds. In this way, the region treated by monatomic hydrogen received a total of about 2.1 pG, corresponding to a dose of about 3.4xl07ions.

[0082] FIG. 10 includes a secondary electron image of the processed sample surface, taken in the same dual-beam FIB-SEM, using the SEM as the source of secondary electrons, as indicated by the system information at the base of the image. The image includes a higher magnification of the region patterned with ionic hydrogen, in discrete regions labeled with the corresponding ionic species. The image, providing higher resolution as well as higher magnification, relative to the FIB image in FIG. 9, reveals an effect of m / z on the resulting surface. Increasing m / z of 1 amu for monatomic hydrogen ions, 2 amu for diatomic hydrogen ions, and 3 amu for triatomic hydrogen ions produces different effects on the surface regions being treated. For example, all three patterned regions exhibit surface blistering that is characteristic of hydrogen bubble formation. Increasing m / z is correlated to a decreasing blister size, as well as an increasing average depth of porosity formation. Advantageously, the techniques of the present disclosure permit the elucidation of species-dependent effects on surface chemistry and morphology, not just at the surface, but also within the near-surface region.

[0083] FIGs. 11-13 are composite diagrams illustrating near-surface regions of the patterned surface of FIGs. 9-10, in cross section, for different constituent hydrogen ions of the beam of FIG. 7, in accordance with some embodiments of the present disclosure. Increasing m / z of the hydrogen ion species of the beam is correlated to a progressively shallower depth at which porosity is observed. Without being bound to a particular physical mechanism or phenomenon, it is contemplated that penetration depth and m / z are positively correlated. Advantageously, the techniques of the present disclosure permit porosity induction in near-surface regions of a sample with specific control of ion species, as well as energy, dose, and spatial localization, in a single sample, in a single operation.

[0084] The techniques for dispersed patterning described herein enable assessment of the respective contributions of different ionic species extracted from complex gas mixtures. The specific case of blister formation and porosity from energetic hydrogen ion irradiation is illustrated in FIGs. 16-18, but other examples include reactive ion etching, milling of polymeric materials, among others. Formation of subsurface porosity is of particular interest to the nuclear energy industry, as the energetic hydrogen ion species illustrated in FIGs. 16-18 are all present in water-cooled reactors under typical operating conditions. Understanding the contributions of respective ionic species for corrosion effects on fuel cladding materials isimportant from an economic and safety point of view, and insight into the different reactivities of the various hydrogen ion species is difficult to obtain with other techniques.

[0085] FIG. 14 is a composite diagram illustrating a titanium surface processed using the mixed-species ion beam of FIG. 7 under a simultaneous patterning approach described in FIGs.5A-6B, in accordance with some embodiments of the present disclosure. FIG. 14 includes an SEM image taken in a dual-beam FIB-SEM, as discussed in reference to FIGs. 9-10. Irradiation by a dispersed beam of ions including a relatively light gas (hydrogen) and a relatively heavy gas (xenon) produced a simultaneously patterned surface including five discrete regions, of which the field of view of the detector includes the three hydrogen species labeled. FIG. 14 is a magnified image of a portion of the pattern, showing the three patterned regions corresponding to hydrogen ions of the beam. The image shown in FIG. 14 is generated using a secondary electron detector (e.g., a “through-the-lens” detector) and does not include significant elemental contrast. In this way, the contrast seen in FIG. 14 reflects a different characteristic secondary electron remission fraction of the treated regions, relative to the native titanium surface, and indicates that a change to the treated surface has occurred, attributable to one of several different sources, including but not limited to contamination, hydride formation, or the like.

[0086] FIG. 15A is an electron microscope image of the same field of view shown in FIG. 14, showing formation of titanium-hydrides in the surface and near surface regions of the sample, in accordance with some embodiments of the present disclosure. FIGs. 15A-15D include SEM images generated using a backscatter (BSE) detector capable of detecting elemental contrast. FIGs. 15B-15D are higher magnification BSE images of portions of the surface treated by monatomic hydrogen ions, diatomic hydrogen ions, and triatomic hydrogen ions, respectively.

[0087] Elemental and compositional analysis indicates that the structures appearing as dark, substantially parallel slivers in the surface correspond to hydrides that form from the covalent bonding of hydrogen with titanium in the metal surface. Each ionic species produced different hydride formations, with the densest being formed under irradiation by triatomic hydrogen and the sparsest being formed under irradiation by diatomic hydrogen, indicating a role of dose in hydride formation. Morphologically, the shape of the hydride patterns differed between the different ionic species, with polyatomic ions forming relatively broad hydrides and monatomic hydrogen ions forming relatively narrow hydrides, indicating a role of ionic chemical structure on hydride formation. Advantageously, the techniques of the present disclosure permit speciesdependency, spatial localization, as well as energetic and dose control of surface chemicalfunctionalization to be varied as part of sample processing, in a single sample and in a single irradiation operation.

[0088] Without being bound to a particular physical mechanism or phenomenon, the formation of hydrides in titanium with species dependent formation density illustrates that analogous approaches can be applied to form nitrides, oxides, sulfides, fluorides, chlorides, or the like, with the same precise control observed in FIGs. 15A-D, where the number of species and distinct treatment zones can be modulated by the composition of the ion source gas, the operating parameters of the plasma source and / or the beam-forming optics, and the magnitude of the dispersal field.

[0089] FIGs. 16A-16B are composite diagrams illustrating a sample surface treated using an undispersed xenon beam in the presence of a hydrogen precursor near the surface of a titanium sample, in accordance with some embodiments of the present disclosure. The trial demonstrated in FIG. 16A shows that a hydrogen-containing precursor, introduced to the vicinity of a sample surface (e.g., by flowing the precursor into the vacuum chamber 110 of the system 100 of FIG. 1) can serve as a hydrogen source for charging a surface with hydrogen. Without being bound to a particular physical mechanism or phenomenon, it is contemplated that a FIB provides energy to decompose the precursor and to promote the diffusion of hydrogen decomposition products into the material of the sample. As demonstrated in FIGs.16A-16B, the extent of the xenon FIB treatment is visually identifiable in FIG. 16A, and the morphology of hydrides formed in the grains of the titanium sample are visible in FIG. 16B. It is noted that the hydride morphology reproduces that found in trials with direct irradiation with hydrogen ion species in a hydrogen-containing FIB, illustrated in reference to FIG. 14 and FIGs. 15A-D.

[0090] FIG. 17A is an electron microscope image displaying a portion of a sample surface following hydrogen FIB treatment, in accordance with some embodiments of the present disclosure. The sample surface corresponds to a polished face of duplex stainless steel, including both austenitic and ferritic phases, as indicated by the various grain boundaries and further mapped in FIG. 17B. In the example embodiment illustrated in FIG. 17A, an undispersed beam of hydrogen ions was focused onto the surface and used to irradiate the portion of the sample surface using a rectangular deflection pattern. The resulting surface defines a relatively light and substantially rectangular portion that has been modified by irradiation under hydrogen ions at an average energy about 2 keV. The resulting surfacerevealed selective blistering associated with austenitic grains, as opposed to ferritic grains that remained relatively smooth. Advantageously, these results, reproduced in other alloyed metal samples (e.g., Fe-MnS grains in 416 Stainless Steel samples), reveal that hydrogen ion delivery using PFIB is site- selective and can target specific microstructural features of a sample.Without being bound to a particular physical mechanism or phenomenon, austenitic (FCC) and ferritic (BCC) steel phases are characterized by different crystal structures with different lattice spacings and orientations, resulting in different physical properties (e.g., austenite is nonmagnetic, ferrite is magnetic). In this way, hydrogen FIB processing provides the ability to study how hydrogen moves through a sample at the resolution of a FIB beam or less in the case of surface microstructures, at a range of beam energy from about 0.1 eV to about 40 keV, including sub-ranges, fractions, and interpolations thereof (e.g., energy of about 0.5 eV).Advantageously, these data reveal that hydrogen FIB addresses challenges in conventional hydrogen charging techniques using electrochemical or high-pressure conditions, which are not site specific, for a range of samples including metal (e.g., Ti, Zr, Fe, steel, Cu, Al, etc.), dielectric (e.g., titania, silica, etc.), and insulating materials (e.g., insulating polymers, biological materials, etc).

[0091] FIG. 17B is a composite diagram including the electron microscope image of FIG. 17A, superimposing a crystal orientation mapping of the portion of a sample surface following hydrogen FIB treatment, in accordance with some embodiments of the present disclosure. FIG.17B was prepared by x-ray techniques for isolating regions of the sample surface associated with [1,1,1], [0,0,1], and [1,0,1] crystal orientations of austenitic steel. The unlabeled regions are associated with ferritic steel. The data of FIG. 17B demonstrate that multimodal analysis techniques can further augment the spatial localization of hydrogen charging information obtainable by FIB-based techniques of the present disclosure. In the specific case of FIG. 17B, the crystal orientation of austenite can permit the effect of crystal orientation on hydrogen charging to be studied in situ, in a multi-phase steel and at the scale of a single grain. This represents a significant improvement in the state of the art in hydrogen charging, relative to conventional techniques that are relatively slow and are spatially generalized.

[0092] FIG. 18 is a composite diagram illustrating a sample surface that has been patterned using a first FIB treatment to mask portions of the surface and a second FIB treatment to irradiate the surface with hydrogen ions, in accordance with some embodiments of the present disclosure. FIG. 18 demonstrates that FIB techniques of the present disclosure can beaugmented with additional FIB processing to improve the spatial resolution of hydrogen-FIB over a broad range of beam energy. Minimum spatial resolution of hydrogen FIB increases (e.g., the spot size increases) with decreasing beam energy, which adversely affects the localization of hydrogen FIB processing at beam energy below about 5 keV. Advantageously, FIB processing can form a mask layer over a portion of a sample, as an approach to spatially localizing hydrogen charging with beam energies at which hydrogen FIB would otherwise be spatially limited. For example, the sample in FIG. 18 includes a zirconium surface that has been repeatedly patterned using a dispersed nitrogen FIB beam, as described in more detail in reference to FIGs. 3A-3C and FIGs. 5A-5C. The scan pattern employed produces parallel portions of the sample surface that are irradiated by monatomic nitrogen ions and diatomic nitrogen ions, and the processing has been repeated to produce an array of treated regions that are vertically separated by about 2 um of untreated Zr surface. As shown by the cross-sectional image in FIG. 18, the irradiation by monatomic nitrogen has produced a relatively thin layer of zirconium nitride (e.g., ZrN) that is coextensive with the patterned portions of the sample surface. Zirconium nitride is characterized by a relatively low permeability to hydrogen, compared to native zirconium.

[0093] The sample has been subsequently patterned by a hydrogen FIB, at an average energy of about 2 keV and a beam current of about 652 pA, at which the average minimum spot size for hydrogen ion beams is greater than the distance between the nitridated regions (e.g., about 2 pm). It is understood that using lower beam energies and higher beam currents degrades the spot size (e.g., enlarges the spot size) of a hydrogen FIB. In this way, the data of FIGs. 18-18 demonstrate that masking regions of a sample surface with a hydrogen barrier layer can improve the spatial resolution of a hydrogen FIB at operating parameters that would otherwise preclude localized and / or species-specific patterning treatments.

[0094] To demonstrate the effectiveness of patterning a hydrogen permeation barrier, the sample has been broadly irradiated with hydrogen FIB over about 35 um by about 50 um, including (e.g., encompassing) all six portions of the sample surface that were previously irradiated by the dispersed nitrogen FIB beam. Hydrogen charging behavior has been examined by sectioning the sample along the dashed line indicated, using a xenon FIB treatment with a beam energy about 30 keV. Advantageously, the techniques of the present disclosure permit the ion source gas to be exchanged between treatments without repositioning the sample or briningthe sample out of vacuum, which improves the purity and quality of hydrogen charging data, and significantly reduces the total processing time of an experiment.

[0095] FIG. 19 is a composite diagram including an electron microscope image of a section of the sample of FIG. 19, and a schematic overlay labeling the resulting compositions of the near-surface region of the sample along the section line indicated in FIG. 18. The image reveals by contrast information that hydrogen propagation into the material was spatially constrained to the area between the nitride-masked portions of the surface. In the image, the zirconium nitride is seen as a relatively thin and dark region of the surface, between which a relatively lighter region of zirconium hydride has formed in a zirconium substrate, visible as the lightest region. Multiple crystal grains of the Zr substrate are also visible in the image, explaining the greyscale variation in the underlying substrate. Without being bound to a particular physical mechanism or phenomenon, zirconium hydride has a relatively low density compared to zirconium, resulting in volumetric expansion of the region between the nitride-masked portions, and a different greyscale contrast in the backscatter SEM images.

[0096] The permeation of hydrogen into the sample is seen to occur both in the vertical and lateral directions, indicative of both beam penetration and diffusion of hydrogen in the zirconium matrix. The maximum depth of the hydride region is indicated by a dashed line, while the lateral extent of hydride is widest at the surface, which can indicate that diffusion along the Zr-ZrN interface is favored, but can also be attributed to gradient-driven species transport. Advantageously, these data reveal phenomena of hydrogen charging at a spatial scale that is entirely unavailable to conventional techniques, and further demonstrate the flexibility of FIB -based approaches of the present disclosure, whereby arbitrary patterning can be used to mask specific portions of a surface in situ, with subsequent spatially localized hydrogen charging at dimensions and energies below those typically available even to hydrogen FIB.

[0097] FIG. 20 is an electron microscope image depicting a portion 2000 of a titanium sample 2005 formed by a preliminary FIB treatment, in accordance with some embodiments of the present disclosure. The portion 2000 of the sample 2005 can be formed using a combination of charged particle beam techniques (e.g., FIB-SEM processing), as described in more detail in reference to FIG. 4. The resulting portion 2000 can be undercut to form a cantilevered section 2010 (e.g., a lamella) by milling a base of the portion 2005 via a trench cut from one or both sides, or can remain bonded to the trench along the base to form a fin. In FIG. 20, the fin hasbeen undercut to form a lamella, being thinner near the freestanding end 2015 of the section 2010, relative to the opposing end 2020 that is anchored to the sidewall of the trench.

[0098] FIG. 21 is a composite diagram including a FIB deflection pattern 2100 superimposed on the section 2010 of the sample 2000 depicted in FIG. 20, in accordance with some embodiments of the present disclosure. In the figure, the deflection pattern 2000 for hydrogen FIB treatment has been overlaid on an electron microscope image of the sample 2000 at a position corresponding to an anchored first end of the cantilevered section 2010.Advantageously, the FIB-based techniques of the present disclosure permit spatially localized hydrogen charging to be implemented as part of multi-parametric experimental designs, including the spatial extent of hydrogen charging (e.g., defined by the deflection pattern 2100), and the hydrogen dose (e.g., defined by beam parameters and / or the dwell time of the beam). In an illustrative example, the deflection pattern 2100 can be defined to be coextensive with a surface of the lamella, which can be a lateral surface, an end surface, or a top / bottom surface of the lamella, based at least in part on the relative orientation of the lamella with the beam axis and controllable in the case of a tilting stage being equipped in the FIB system.

[0099] FIG. 22 is an electron microscope image depicting the resulting surface 2205 of the section 2010 of FIG. 20 following the treatment depicted in FIG. 21, in accordance with some embodiments of the present disclosure. Qualitative assessment reveals that the portion 2205 of the surface that was subjected to hydrogen FIB irradiation (e.g., corresponding to deflection pattern 2100 of FIG. 21) exhibits visibly distinct properties in secondary electron images, generated using an SEM. The portion of the lamella that has been irradiated by hydrogen FIB is visibly darker than the untreated portion. The brightness of a surface in secondary electron imaging can correspond to a difference in secondary electron reemission fraction, reflecting a potential electronic effect of the hydrogen-FIB treatment. As described in more detail in reference to FIGs. 23A-23D, the relatively dark region in FIG. 22 corresponds to an embrittled region that has been charged with hydrogen, as demonstrated in micromechanical tests under lateral bending strain.

[0100] FIGs. 23A-23D are composite diagrams illustrating two example sequences making up a controlled micromechanical test of a cantilevered section, in accordance with some embodiments of the present disclosure. FIGs. 23A-23B correspond to a negative control test, in which a probe tip is used to apply a lateral force to a lamella that has not been subjected to localized hydrogen charging described in reference to FIG. 20-22. FIGs. 23C-23D correspondto a sample test, in which the probe tip is used to apply the same lateral force to a lamella that has been subjected to localized hydrogen charging. FIGs. 23A-23D include electron microscope images that depict an initial state (FIG. 23A and FIG. 23C) and a deformed state (e.g., FIG. 23B and FIG. 23D) of each respective lamella. In the example tests shown, hydrogen charging using a PFIB technique of the present disclosure, localized to a portion of the lamella as illustrated in FIG. 21, resulted in a significant decrease in deformation on relaxation of the sample, for substantially equal deflection angle, relative to the negative control. Quantitative data are presented in FIG. 23E. The deflection angle applied by the probe tip was controlled by using an equivalent motion of the probe, applied to a consistent position on the cantilevered section, and for a comparable time before removing the stress.Advantageously, the results in FIGs. 23A-23D demonstrate that localized hydrogen charging enables sensitive and quantitative in-situ measurement of hydrogen embrittlement in additional and / or alternative modalities to dimple-indenter testing or other techniques available in microanalytical systems. Where quantitative information for deformation is available, material properties of the sample can be estimated (e.g., Young's modulus, modulus of elasticity, plastic deformation transitions, etc.) as part of an experimental design including multi-parametric studies of hydrogen charging extent, hydrogen dose, and force application (e.g., force-rate, etc.).

[0101] FIG. 23E is a data plot charting example data for the tests described in reference to FIGs. 23A-D. The data demonstrate the quantitative effect of hydrogen charging on mechanical properties of the cantilevered section that was treated as described in reference to FIGs. 20-22. The lateral “x” axis of the plot shows a deflection angle under strain, applied using the probe as illustrated in FIG. 23A and FIG. 23C, and the vertical “y” axis shows the angle after the strain is removed and the cantilevered section is left to relax into a new state. As such, the plot reflects the hysteresis that is observed in material properties and how that is affected by hydrogen FIB treatment, from which the impact on properties such as ductility can be deduced.

[0102] Two data sets are shown in FIG. 23E. The solid black markers correspond to a sample that was treated using a hydrogen FIB to charge at least a region of the sample with hydrogen. The solid white markers correspond to a negative control sample that was prepared without hydrogen charging. The two data sets differ significantly in the slope of the stress-relaxation angle. For the control sample, a relatively higher slope in the data reflects higher ductility and a lower threshold for plastic deformation. In contrast, charging at least a portion of the samplewith hydrogen prior to placing the cantilevered section under strain increases the extent of relaxation and lowers the relaxed angle, which reflects an embrittlement effect of the treatment. This is visually confirmed in the micrographs shown in FIGs. 23A-D.

[0103] FIGs. 24A-24B are schematic diagrams illustrating an in-situ force sensor 2400 adapted for use in the micromechanical test of FIGs. 24A-24D, in accordance with some embodiments of the present disclosure. The force sensor 2400 includes a cantilevered portion 2405. fixed to a calibrated base portion 2410 at a first end 2415 and suspended at a second end 2420. The base portion 2410 is mechanically coupled to a micromechanical probe tip 2325, as described in more detail in reference to FIGs. 20-23D. The sensor 2400 defines a gap 2430 between the cantilevered portion 2405 and the base portion 2410. Material properties and geometric properties of the sensor 2400 can be defined in such a way that the sensor 2400 is calibrated to measure a lateral force exerted on the second end 2420 by observing and quantifying a deflection of the second end 2420 toward to the base portion 2410. To improve the linearity of the lateral force, the cantilevered portion 2405 can define a contact feature 2435 on a surface 2440 of the second end 2420 opposite the gap 2430. The contact feature 2435 can be rounded in one or more dimensions, such that a contact force between the second end 2420 and a corresponding surface of a sample 2445 can be transformed into a lateral force, substantially opposing a motion of the probe tip 2425 and substantially normal to the surface 2440 of the second end 2420.

[0104] In an illustrative example of FIG. 23B, the gap 2430 can be quantified in electron microscope images (e.g., using an SEM) while a lateral contact force is applied to the sample 2445. Without being bound to a particular physical mechanism or phenomenon, material properties of an elongate portion 2450 of the sample 2445 (e.g., a lamella, fin, rod, etc.) can be estimated by straining the elongate portion 2450, by measuring one or more geometrical properties of the elongate portion 2450, and by measuring a width of the gap 2430. The gap width can be a function of the lateral force exerted on the second end 2320, which can be related to the material properties of the sample 2445 by mathematical relations for various moduli (e.g., Young's modulus). Further, measuring the width of the gap 2430 as a function of motion of the probe tip 2425 can reveal dynamic properties of the sample 2445, such as measuring plastic deformation threshold(s).

[0105] Advantageously, the sensor 2400 of FIGs. 24A-24B provides an in-situ calibrated method for measuring the effect of localized hydrogen embrittlement on material properties. Inan example, the effect of localized hydrogen charging, as shown in FIGs. 21-22, can be assessed in comparison to control samples both visually (e.g., using image sequences as shown in FIG. 23A-23D) and quantitatively, by measuring the deflection force applied to the sample.

[0106] FIG. 25 is a block flow diagram illustrating an example process for micromechanical testing of a section of a sample, in accordance with some embodiments of the present disclosure. One or more operations of the example process can be executed by a charged-particle beam system, such as the dual-beam FIB-SEM system 100 of FIG. 1, or by an analogous single-beam or multi-beam configuration. The system can include control circuitry and data-processing logic configured to coordinate operation of the focused-ion-beam (FIB) column 111, the scanning-electron-microscope (SEM) column 107, and any micromanipulation subsystems, including the stage controls 127 and probe-type actuators. In this way, sample positioning, hydrogen charging, imaging, and force-application steps can be performed automatically or pseudo-automatically under control of stored instructions, with optional user initiation via a graphical interface. While the process of FIG. 25 is described as a sequence of discrete operations, one or more operations can be omitted, repeated, reordered, or substituted. Additional operations such as vacuum initialization, stage calibration, or beam-alignment routines may precede or follow the sequence. Moreover, operations can be executed serially or in parallel depending on system configuration and throughput preferences.

[0107] At operation 2505, the process includes positioning a sample (e.g., Sample 1905 of FIG. 20) that will be subjected to micromechanical testing. The sample can be substantially homogeneous or can be heterogeneous (e.g., including multiple layers or other internal structures), as when duplex alloy or CMOS integrated circuit is processed to define a cantilevered section formed from the material of the sample, which can include a lamella or fin. Operation 2405 can include one or more sub-operations for positioning and / or orienting the sample relative to a beam axis (e.g., beam axis B of FIG. 1) to permit FIB milling at operation 2510. This can include tilting the sample to be face-on to the FIB column (e.g., column 111 of FIG. 1) and / or to be at a relatively low angle relative to the FIB column, to enable trenchmilling. Positioning the sample can also include navigating the stage such that a specific region of interest (ROI) of the sample is prepared for testing. This can include on or more steps for registering a location of the ROI on the sample and generating stage motion instructions to move the sample to the appropriate position or set of positions.

[0108] At operation 2510, the process can include forming the elongate protrusion 2010 from the bulk sample 2005 using the FIB column 111. The elongate protrusion can be prepared by FIB milling (e.g., using FIB 200 of FIG. 2A). As described in more detail in reference to FIG.19, a preliminary FIB treatment can undercut a portion of the sample to produce the freestanding section, thinner near its distal end relative to its anchored end. The resulting geometry can exhibit a length-to-thickness ratio from about 10:1 to about 0.5:1, including subranges, fractions, and interpolations thereof. In an illustrative example, a cantilevered section can be formed 2:1, and in some embodiments substantially higher, consistent with claim 19. The sample can be supported on the stage 125 (FIG. 1), oriented such that the elongate protrusion extends laterally relative to the FIB beam axis B and the SEM beam axis A, facilitating both ion-beam processing and electron-beam imaging within a single vacuum environment. As shown in FIGs. 20-21, FIB milling can define trenches adjacent to a region of interest to produce a cantilever suitable for micromechanical testing. This operation may also include thinning of the lamella to a desired cross-sectional dimension, ensuring mechanical compliance under subsequent lateral loading.

[0109] At operation 2515, the process can include charging a localized region of the section using the FIB device to create a hydrogen-charged region 2205. Hydrogen implantation can be carried out by directing a beam of hydrogen ions extracted from the plasma source 205 of FIG.2A, through the ion column 210, toward a designated surface area defined by the scan pattern (e.g., pattern 2100 of FIG. 21). The FIB parameters — energy, dwell time, and current — can be selected to achieve a predetermined hydrogen dose. As shown in FIG. 21, the charged region may appear darker in secondary-electron images acquired by a SEM, reflecting altered secondary electron reemission due to hydrogen incorporation. The degree and spatial extent of charging can be verified using correlated SEM imaging or energy-dispersive spectroscopy before mechanical loading. In some embodiments, operation 2515 precedes operation 2510, such that the cantilever is milled from a portion of the substrate that has been charged with hydrogen.

[0110] At operation 2520, the process includes applying a controlled force against the elongate protrusion in accordance with a predetermined parameter. Force application can be performed using the in-situ force sensor 2400 shown in FIGs. 24A-24B, in which a probe tip 2425 exerts a lateral load via contact feature 2435 of the sensor’s cantilevered portion 2305. The predetermined parameter can correspond to a displacement amplitude, an applied load, oran angular deflection rate, depending on the desired test modality. The motion of the probe can be coordinated with automated stage controls 127, ensuring that the force is applied substantially parallel to or inward toward the sample surface. The test configuration may replicate that shown in FIGs. 23A-23D, in which lateral strain is applied along the minor dimension of the lamella.

[0111] At operation 2525, the process includes removing the applied force once the predetermined displacement or time interval has been achieved. The probe tip 2425 can be retracted along a controlled trajectory to controllably eliminate lateral stress on the elongate protrusion 2010. During unloading, the FIB-SEM system can record live-image data from the SEM column 107, capturing the relaxation behavior of the protrusion. Completion of force removal can be verified when the contact gap 2430 (FIG. 24B) returns to its baseline width or when cessation of elastic rebound is detected (e.g., in SEM images).

[0112] At operation 2530, the process includes obtaining a post-force image of at least the hydrogen-charged portion 2205 of the elongate protrusion. The image can be captured by the SEM column 107 using secondary-electron or backscatter-electron detection. In some embodiments, the imaging parameters are optimized to minimize additional charging or drift — e.g.. beam energy between about 1 keV and 5 keV and short dwell times. The image can serve as the “second image” in a sequence of frames (e.g., before and after deformation) used to quantify displacement. These imaging operations correspond functionally to the datasets illustrated in FIGs. 23A-23D, where pre- and post-deflection states were compared.

[0113] At operation 2535, the process can optionally include obtaining a one or more images of the section before and after the application of the force. For example, a first image of the section can be generated before the application of the force and a second image of the section can be generated after the application of the force. One or more images can be generated before the first image, between the first image and the second image, and / or after the second image. The first image can be acquired under identical magnification and detector conditions as the second image. Maintaining consistent imaging parameters can facilitate accurate digital correlation and calibrated measurement of spatial displacement, mechanical hysteresis, feature size(s), or the like. The two images can then be stored in the control system’s data structure for computational displacement mapping.

[0114] At operation 2540, the process includes measuring a displacement parameter of the section based on the obtained image(s). The measurement can be derived from the angulardeviation or linear deflection of the free end 2015 relative to the anchored end 2020, using image-processing algorithms (e.g., an automated approach and / or human techniques for spatial measurement). In embodiments employing the in-situ force sensor 2400, the measured gap 2430 can be correlated to the lateral force applied, thereby yielding stress-strain characteristics such as Young’s modulus or yield strength of the hydrogen-charged region. The deformation magnitudes observed as demonstrated qualitatively in FIG. 23A-23D and quantitatively in FIG.23E exemplify this measurement approach. The resulting data set — force, displacement, and image correlation — can be exported for quantitative analysis of hydrogen embrittlement effects.

[0115] Optionally, the process 2500 can include operations for concluding the micromechanical test by releasing the probe tip and storing the measured data. The system controller can log applied-force waveforms, displacement maps, and imaging metadata into a unified record. Subsequent microanalysis or repeat testing under varied beam parameters (e.g., hydrogen dose, implantation energy) can then be scheduled within the same vacuum session, maintaining spatial registration with the previously tested region.

[0116] Advantageously, embodiments of the present disclosure integrate hydrogen charging, micromechanical loading, and high-resolution imaging into a single in-situ workflow, eliminating the need for ex-situ transfer between instruments. The process 2500 of FIG. 25 leverages dual-beam FIB-SEM systems (e.g., system 100 of FIG. 1), hydrogen-implantation methods of FIGs. 2A-4, and mechanical-testing configurations of FIGs. 19-23B to achieve nanoscale measurement of hydrogen-charging effect on mechanical stress (e.g., stress-induced deformation). This integration yields enhanced reproducibility, spatial precision, and environmental stability relative to conventional hydrogen-charging tests. Additionally, it significantly reduces loss of hydrogen from the sample by diffusion. In this way, the disclosed techniques enable quantitative assessment of localized hydrogen embrittlement and related material property changes while remaining compatible with standard FIB-SEM workflows and automation frameworks.

[0117] FIG. 26 is a composite diagram depicting a palladium sample surface following oxidation by a dispersed beam of oxygen ions, in accordance with some embodiments of the present disclosure. The sample surface was prepared using the techniques described in reference to FIGs. 3A-3B, using an oxygen PFIB, as described in more detail in reference to FIGs. 2A-2B. The sample surface was irradiated using beamlets of monatomic oxygen ions anddiatomic oxygen ions, dispersed by being directed through a magnetic field. The resulting surface includes two portions (e.g., portions 500 of FIG. 5A) that have been oxidized.

[0118] FIG. 27 is a composite diagram illustrating an elemental mapping of the sample surface of FIG. 26, in accordance with some embodiments of the present disclosure. The elemental mapping can be generated using energy-dispersive spectroscopy in systems that have been equipped with EDS detectors. The elemental mapping can also be generated using ionbeam based techniques, such as TOF-SIMS. when enabled. The resulting mapping reveals that oxidation occurred to a greater degree in the portion irradiated by monatomic oxygen ions, relative to the portion irradiated by diatomic oxygen ions. For both portions, however, the oxidation was coextensive with the treated surface area defined by the deflection pattern (e.g., deflection pattern 525 of FIG. 5A).

[0119] FIG. 28 is a composite diagram depicting the sample surface of FIG. 26 following spatially localized reduction by an undispersed beam of hydrogen ions, in accordance with some embodiments of the present disclosure. Advantageously, the techniques of the present disclosure permit in situ surface studies of heterogeneous chemical reactions, for which multip arameteric experimental design extends to beam parameters (e.g., beam energy, beam current, ion flux, total ion dose, dispersal extent, etc.), as well as sample characteristics (e.g., surface chemistry, presence of adsorbed surface species, etc.). In the example of FIG. 28, the oxidized portions of the palladium sample have been exposed to an undispersed hydrogen ion beam at an average energy of about 30 keV. The resulting surface exhibits visual characteristics of a native palladium surface, in terms of relative brightness, as opposed to the contiguous oxidized region that was not subjected to hydrogen-FIB treatment that remains relatively dark. The same result was observed in both oxidized portions.

[0120] FIG. 29 is a composite diagram illustrating an elemental mapping of the sample surface of FIG. 28, in accordance with some embodiments of the present disclosure. FIG. 29 was produced using the same or similar techniques as in FIG. 27, such that the change in the palladium surface is directly comparable with the mapping in FIG. 27. To that end, the area exposed to hydrogen FIB irradiation shows a significant decrease in oxygen composition, with oxygen signal in both treated portions being comparable to background. Without being bound to a particular physical mechanism or phenomenon, the effect of the hydrogen FIB treatment can reduce palladium oxide formed by oxygen FIB preprocessing, with the chemical reductionreaction being spatially localized to portions of the oxidized surface corresponding to the deflection pattern of the hydrogen FIB.

[0121] FIG. 30 is a composite diagram depicting the sample surface of FIG. 28 following a second spatially localized reduction by a dispersed beam of hydrogen ions at a lower beam energy, in accordance with some embodiments of the present disclosure. FIG. 28 is provided to demonstrate the range of average beam energy over which chemical reduction of palladium oxide was observed and to control for potential alternative explanations, such as mechanical sputtering, for the observed EDS data. From these data, it was found that a hydrogen FIB at an average beam energy of about 5 keV induced localized chemical reduction of palladium oxide, coextensive with the overlap of the hydrogen-FIB deflection pattern and the oxidized region of the surface. These visual findings are supported by elemental mapping, shown in FIG. 31.

[0122] FIG. 32 is a block flow diagram illustrating an example process 3200 for spatially localized chemical reduction of a sample, in accordance with some embodiments of the present disclosure. One or more operations of the process 3200 can be executed by control circuitry of a charged particle system such as the dual-beam FIB-SEM system 100 of FIG. 1, the plasmabased FIB system 200 of FIGS. 2A-2B, or another analytical system described herein. In some embodiments, the controller operates in communication with the ion source 110. the beamforming optics of the FIB column 111, the gas injection system (GIS) 115, and the sample stage 125 to perform a reduction process on a selected region of a sample 130 within the vacuum chamber 120. At least a subset of the operations can be performed automatically or pseudo-automatically based on stored machine-readable instructions, while user input may be used to select the region of interest or adjust irradiation parameters. While the process 3200 is presented as a sequence of operations, one or more operations can be omitted, repeated, or executed in a different order. Additional preparatory operations such as plasma ignition, beam calibration, or precursor stabilization can precede or follow the described sequence, and operations can be performed in series or in parallel depending on implementation.

[0123] At operation 3205, the process includes identifying a target location on the sample 130 at which chemical reduction is to be performed. The identification can be carried out using the imaging capability of the SEM column 107, while the FIB column 111 remains idle, or using stored pattern data corresponding to a region of interest (ROI), such as the oxidized palladium regions shown in FIG. 25. The control system can register the coordinates of the target location with sub-micron accuracy, such that subsequent beam operations are coextensive with thedesired area. In this way, the reduction can be confined to an ROI smaller than the total area of the sample surface.

[0124] At operation 3210, the process includes computing irradiation parameters to be used to perform the chemical reduction. These parameters can include beam energy, beam current, ion dose, dwell time, beam overlap and / or pixel spacing of the deflection pattern, and the inlet gas pressure and radio-frequency (RF) power applied to the plasma discharge (e.g„ discharge 245 of the ion source 205, as shown in FIG. 2B). The controller can determine an appropriate combination of these parameters based on material type, oxidation depth, or desired reduction rate. In some embodiments, the parameters are selected such that the reduction can be carried out at or near ambient temperature. The computation can also include determining whether to employ a pure reducing ion beam or a mixed-species beam including inert or non-reducing ions. For instance, the irradiation parameters may define a beam of hydrogen ions, ammonia ions, or a combination of hydrogen, nitrogen, and / or xenon ions, such as those characterized in FIG. 7.

[0125] At operation 3215, the process includes using the computed irradiation parameters to generate reducing ions. The plasma-based ion source 205 is energized using RF power supplied by the power circuitry 225 to ignite a discharge in a reducing gas, such as hydrogen or ammonia, or in a gas mixture including a reducing gas and a relatively inert carrier gas, as illustrated in FIGS. 2A-2B. Ions extracted from the discharge are accelerated through extraction optics 265 to form a beam of reducing ions having a defined energy and current density. In some embodiments, the irradiation parameters control both the energy of extraction and the gas composition to achieve a desired ratio of reducing ions to non-reducing ions. In certain implementations, the irradiation parameters are defined to form a mixed ion beam comprising both reducing and non-reducing ions, such that concurrent sputtering, activation, or cleaning of the surface occurs as the reduction proceeds. The ratio of ionic species can be dynamically adjusted during the process by varying the RF power or the relative flow rates of gases through the gas-supply system 230.

[0126] At operation 3220, the process includes delivering the generated reducing ions to the target location. In some embodiments, the FIB column 111 directs the beam toward the region identified at operation 3205, following a scan pattern stored by the controller. The scan pattern can correspond to a raster, vector, or other deflection scheme that defines the spatial distribution of ion dose across the target region. The reducing ions impinge on the surface andchemically reduce the oxidized species, restoring the underlying metallic composition as shown in FIGS. 27 and 28.

[0127] In some embodiments, additionally and / or alternatively, reactive ions are generated in situ by irradiating a reactive ion precursor introduced to the vicinity of the target region through the GIS 115. Suitable precursors can include water vapor, methyl nitroacetate, ammonia, or hydrogen gas, which decompose under irradiation by a charged particle beam such as a gallium ion beam, xenon ion beam, or electron beam. The decomposition liberates reducing ions that participate in the subsequent surface reduction. The GIS 115 can maintain a controlled gas flux toward the surface while the vacuum system 215 regulates chamber pressure to ensure beam stability and precursor replenishment.

[0128] At operation 3225, the process can include heating the sample 130 to promote chemical reduction at the target location. Heating can be provided by a resistive heater integrated in the stage 125, by radiative elements coupled to the vacuum chamber 120, by laser irradiation, or by localized beam-induced heating from sustained irradiation. The elevated temperature can enhance surface reaction kinetics or facilitate diffusion of hydrogen species within the near-surface region. The heating parameters can be chosen such that the temperature remains within a range that avoids morphological deformation of the sample surface. After the prescribed dose or time interval, the system can determine that the reduction is complete based on endpoint detection criteria, such as a change in secondary-electron emission, an optical signal, or an elemental analysis showing removal of oxygen from the treated region.

[0129] Upon completion, the sample can be analyzed in situ using the SEM column 107 to generate images comparable to the data shown in FIGS. 27 through 30, confirming restoration of the native and / or chemically-reduced surface (e.g., metallic, semiconductor, oxide, etc.). Advantageously, the process 3200 enables spatially localized chemical reduction using a charged particle system, providing micrometer scale or nanometer scale control over surface reduction without resorting to typical bulk chemical processing. Further, as each operation is executed within the same vacuum environment and coordinated by the system controller, the method allows precise registration between oxidized and reduced regions. The techniques of FIG. 32 are compatible with mixed-gas plasma sources, multi-beam workflows, and automation schemes described in reference to FIGS. 1 through 3C, improving throughput, repeatability, and selectivity in ion-beam-based chemical modification and reduction processes.

[0130] In the preceding description, various embodiments have been described. For purposes of explanation, specific configurations and details have been set forth in order to provide a thorough understanding of the embodiments. However, it will also be apparent to one skilled in the art that the embodiments may be practiced without the specific details. Furthermore, well-known features may have been omitted or simplified in order not to obscure the embodiment being described. While example embodiments described herein center on charged particle beam systems, and dual-beam FIB systems in particular, these are meant as non-limiting, illustrative embodiments. Embodiments of the present disclosure address analytical instruments systems for which a wide array of material samples can be analyzed to determine chemical, biological, physical, structural, or other properties, among other aspects, including but not limited to chemical structure, trace element composition, or the like. Further, embodiments of the present disclosure can be applied in systems configured for automated (e.g., performing one or more processes or operations without human involvement), pseudo-automated (e.g., performing one or more processes or operations with limited human involvement and / or with human initiation), and / or manual processes or operations for sample preparation (e.g., in lamella preparation) workflows, for example, as would be used in metrology of semiconductor samples.

[0131] Some embodiments of the present disclosure include a system including one or more data processors and / or logic circuits. In some embodiments, the system includes a non-transitory computer readable storage medium containing instructions which, when executed on the one or more data processors and / or logic circuits, cause the one or more data processors and / or logic circuits to perform part or all of one or more methods and / or part or all of one or more processes and workflows disclosed herein. Some embodiments of the present disclosure include a computer-program product tangibly embodied in non-transitory machine-readable storage media, including instructions configured to cause one or more data processors and / or logic circuits to perform part or all of one or more methods and / or part or all of one or more processes disclosed herein.

[0132] The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the claims. Thus, it should be understood that although the present disclosure includes specific embodiments and optional features, modification and variation of the concepts herein disclosed may be resortedto by those skilled in the art, and that such modifications and variations are considered to be within the scope of the appended claims.

[0133] Where terms are used without explicit definition, it is understood that the ordinary meaning of the word is intended, unless a term carries a special and / or specific meaning in the field of charged particle microscopy systems or other relevant fields. The terms “about” or “substantially” are used to indicate a deviation from the stated property within which the deviation has little to no influence of the corresponding function, property, or attribute of the structure being described. In an illustrated example, where a dimensional parameter is described as “substantially equal” to another dimensional parameter, the term “substantially” is intended to reflect that the two parameters being compared can be unequal within a tolerable limit, such as a fabrication tolerance or a confidence interval inherent to the operation of the system. Similarly, where a geometric parameter, such as an alignment or angular orientation, is described as “about” normal, “substantially” normal, or “substantially” parallel, the terms “about” or “substantially” are intended to reflect that the alignment or angular orientation can be different from the exact stated condition (e.g„ not exactly normal) within a tolerable limit. For numerical values, such as diameters, lengths, widths, or the like, the term “about” can be understood to describe a deviation from the stated value of up to ±10%. For example, a dimension of “about 10 mm" can describe a dimension from 9 mm to 11 mm.

[0134] The description provides exemplary embodiments, and is not intended to limit the scope, applicability or configuration of the disclosure. Rather, the ensuing description of the exemplary embodiments will provide those skilled in the art with an enabling description for implementing various embodiments. It is understood that various changes may be made in the function and arrangement of elements without departing from the spirit and scope as set forth in the appended claims. Specific details are given in the description to provide a thorough understanding of the embodiments. However, it will be understood that the embodiments may be practiced without these specific details. For example, specific system components, systems, processes, and other elements of the present disclosure may be shown in schematic diagram form or omitted from illustrations in order not to obscure the embodiments in unnecessary detail. In other instances, well-known circuits, processes, components, structures, and / or techniques may be shown without unnecessary detail.

Claims

CLAIMSWhat is claimed is:

1. A method of processing a workpiece in a focused ion beam system, the method comprising:generating a plasma in an ion source gas comprising hydrogen;extracting a beam of hydrogen ions from the plasma;directing the beam toward a region of a workpiece, in accordance with a scan pattern; andcharging the region of the workpiece with hydrogen.

2. The method of claim 1, wherein generating the plasma comprises inductively coupling an electromagnetic field into the ion source gas using a radio frequency power supply.

3. The method of claim 2, wherein generating the plasma comprises coupling from about 100 W to about 400 W of RF power into the plasma.

4. The method of claim 1, wherein the beam of hydrogen ions comprises multiple ionic species of hydrogen.

5. The method of claim 4, wherein the beam comprises a relatively high fraction of monatomic hydrogen ions and a relatively low fraction of polyatomic hydrogen ions.

6. The method of claim 4, wherein the beam comprises a relatively high fraction of polyatomic hydrogen ions and a relatively low fraction of monatomic hydrogen ions.

7. The method of claim 4, further comprising directing the beam of hydrogen ions through a magnetic field, the magnetic field being oriented relative to a beam axis of the focused ion beam system to spatially disperse the ions over a surface of the workpiece.

8. The method of claim 7, wherein charging the region of the workpiece comprises delivering a substantially isolated ionic species of the multiple ionic species of hydrogen to the region.

9. The method of claim 1, further comprising, prior to generating the plasma, forming a hydrogen barrier layer over at least a portion of a surface of the workpiece, the portion of the surface including the region.

10. The method of claim 9, wherein the plasma is a first plasma, wherein the ion source gas is a first ion source gas, the beam of hydrogen ions is a first beam, and wherein forming the hydrogen barrier comprises:generating a second plasma in a second ion source gas, different from the first ion source gas;extracting a second beam of ions from the second plasma; anddirecting the second beam of ions toward at least the portion of the surface of the workpiece.

11. The method of claim 10, wherein the second ion source gas comprises a rare gas, the method further comprising introducing a precursor to the surface of the workpiece, the decomposition of which induces the formation of the hydrogen barrier.

12. The method of claim 11, wherein the precursor comprises a mixture of tetraethyl orthosilicate and water vapor.

13. The method of claim 10, wherein the second ion source gas comprises nitrogen gas and wherein the hydrogen barrier comprises a nitride.

14. The method of claim 10. wherein the second ion source gas comprises oxygen and wherein the hydrogen barrier comprises an oxide.

15. The method of claim 9, wherein the scan pattern is a first scan pattern, and wherein forming the hydrogen barrier comprises:introducing a precursor to the surface of the workpiece; anddirecting a focused electron beam toward at least the portion of the surface of the workpiece, in accordance with a second scan pattern, different from the first scan pattern.

16. The method of claim 9, further comprising removing at least part of the hydrogen barrier to define a mask.

17. A Focused Ion Beam (FIB) system, comprising:one or more ion sources;control circuitry operably coupled with the one or more ion sources; andone or more machine-readable media, storing executable instructions for operating the FIB system that, when executed, cause the control circuitry to perform operations comprising:generating a plasma in an ion source gas comprising hydrogen;extracting a beam of hydrogen ions from the plasma;directing the beam toward a region of a workpiece, in accordance with a scan pattern; andcharging the region of the workpiece with hydrogen.

18. The FIB system of claim 17, wherein the operations further comprise operations of the methods of claims 2-16 alone or in combination.

19. A method for processing a workpiece in a charged particle system, the method comprising:positioning a sample including an elongate protrusion formed therefrom, the elongate protrusion including a hydrogen-charged region;applying a force against the elongate protrusion in accordance with a predetermined parameter;removing the force;obtaining an image of at least the hydrogen-charged portion of the elongate protrusion after the removal of the force; andmeasuring a displacement parameter of the elongate protrusion in the image.

20. The method of claim 19. wherein the charged particle system includes a Focused Ion Beam (FIB) device.

21. The method of claim 20. further comprising:charging a region of the elongate protrusion of the sample, using the FIB device, to create the hydrogen-charged region.

22. The method of claim 20, further comprising:milling the sample, using the FIB device, to form the elongate protrusion therefrom.

23. The method of claim 22, wherein the sample includes the hydrogen-charged region, and wherein milling the sample includes removing hydrogen-charged material of the sample to form the elongate protraction.

24. The method of claim 19. wherein the charged particle system includes a Scanning Electron Microscope (SEM) device; andwherein the image is obtained using the SEM.

25. The method of claim 19, wherein a first dimension of the elongate protrusion, extending outward from the sample, is at least two times greater than a second dimension of the elongate protrusion, the second dimension being substantially perpendicular to the first dimension.

26. The method of claim 25,wherein the elongate protrusion has a substantially planar shape that extends outward from the sample; andwherein the application of the force is in a direction substantially parallel to the second dimension.

27. The method of claim 25, wherein the application of the force is in an inward direction toward the sample.

28. The method of claim 20, wherein the application of the force is via a manipulation needle of the charged particle system.

29. The method of claim 19, wherein the predetermined parameter is one of: a predetermined displacement; and a predetermined force.

30. The method of claim 29,wherein the application of the force is along an axis; andwherein the predetermined displacement is a predetermined change of a position of the elongate protrusion along the axis.

31. The method of claim 29,wherein the elongate protrusion extends away from the sample along a directional axis; andwherein the predetermined displacement is a predetermined change of an angle of the elongate protrusion with respect to the directional axis.

32. The method of claim 19, wherein the image is a second image of a set of images of at least the hydrogen-charged portion of the elongate protrusion including a first image and the second image, further comprising:obtaining the first image before the application of the force.

33. The method of claim 32, wherein the measurement of the predetermined parameter is based upon the first image.

34. A Focused Ion Beam (FIB) system, comprising:one or more ion sources;control circuitry operably coupled with the one or more ion sources; andone or more machine-readable media, storing executable instructions for operating the FIB system that, when executed, cause the control circuitry to perform operations comprising:positioning a sample including an elongate protrusion formed therefrom, the elongate protrusion including a hydrogen-charged region;applying a force against the elongate protrusion in accordance with a predetermined parameter;removing the force;obtaining an image of at least the hydrogen-charged portion of the elongate protrusion after the removal of the force; andmeasuring a displacement parameter of the elongate protrusion in the image.

35. The FIB system of claim 34, wherein the operations further comprise operations of the methods of claims 1-33 alone or in combination.

36. A method for a charged particle system, the method comprising:identifying a target location on a sample at which chemical reduction is to be performed; computing irradiation parameters to be used to perform the chemical reduction; using the irradiation parameters to generate reducing ions; anddelivering the reducing ions to the target location.

37. The method of claim 36, wherein the irradiation parameters are used to cause a reducing ion beam to be formed from a reducing ion source, and wherein irradiating the target location with the reducing ion beam delivers the reducing ions to the target location.

38. The method of claim 37. wherein the reducing ion source is a hydrogen ion source.

39. The method of claim 37, wherein the reducing ion source is an ammonia ion source.

40. The method of claim 36, further comprising supplying a reducing ion precursor at the target location and irradiating the reducing ion precursor with a charged particle beam, the charged particle beam formed based on the irradiation parameters, to generate the reducing ions.

41. The method of claim 40. wherein the charged particle beam is one of a gallium ion beam, a xenon ion beam, or an electron beam.

42. The method of claim 40. wherein the precursor comprises one or more of water, methyl nitroacetate, ammonia, carbon monoxide, formic acid, oxalic acid, sulfur dioxide, tetraethyl orthosilicate (TEOS), trifluoroacetamide, tetramethylcyclotetrasiloxane (TMCTS), pentamethylcyclopentasiloxane (PMCPS), hexamethylcyclohexasiloxane (HMCHS) or hydrogen gas.

43. The method of claim 36, wherein the target location is less than a total area of the sample.

44. The method of claim 36. wherein the irradiation parameters comprise an ion beam energy and / or an RF power.

45. The method of claim 36. further comprising heating the sample to promote the chemical reduction at the target location.

46. The method of claim 36, wherein the irradiation parameters are used to form a mixed ion beam comprising non-reducing ions and the reducing ions, and wherein irradiating the target location with the mixed ion beam delivers the reducing ions to the target location.

47. The method of claim 36, wherein computing the irradiation parameters comprises determining a beam energy to be used to irradiate the target location with an ion beam to perform the chemical reduction at ambient temperature.

48. A Focused Ion Beam (FIB) system, comprising:one or more ion sources;control circuitry operably coupled with the one or more ion sources; andone or more machine-readable media, storing executable instructions for operating the FIB system that, when executed, cause the control circuitry to perform operations comprising:identifying a target location on a sample at which chemical reduction is to be performed; computing irradiation parameters to be used to perform the chemical reduction; using the irradiation parameters to generate reducing ions; anddelivering the reducing ions to the target location.

49. The charged particle system of claim 48, wherein the reducing ions are delivered to the target location to chemically reduce a target proportion of a chemical species.

50. The charged particle system of claim 48, wherein the reducing ions are delivered to the target location to alter a chemical reactivity of the sample at the target location.

51. The charged particle system of claim 48, wherein the reducing ions are delivered to the target location to increase a purity and / or conductivity of the sample at the target location.

52. The charged particle system of claim 48, wherein the reducing ions are delivered to the target location to restore an activity of a catalytic material.

53. The charged particle system of claim 48, wherein the reducing ions are delivered to the target location to cause the target location to be etched at a different rate than at regions of the sample outside of the target location.

54. The FIB system of claim 34, wherein the operations further comprise operations of the methods of claims 1-47, alone or in combination.

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