Heating assembly for charged particle beam system

Abstract

To provide an improved sample heating system that is usable together with an EDS detector.SOLUTION: Systems, devices, and techniques for heating a sample are described. A heating assembly can include a membrane. The membrane can include carbon nanotube material. The heating assembly includes a support, mechanically coupled with the membrane. The support can be configured to integrate with a charged particle beam system. The heating assembly also includes a heating circuit, electrically coupled with the membrane. The heating circuit can be configured to direct an electrical current through the membrane.SELECTED DRAWING: Figure 2A

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Provisional Patent Application No. 18 / 595,124, filed March 4, 2024, the disclosure of which is incorporated herein by reference in its entirety.

[0002] FIELD OF THE DISCLOSURE Embodiments of the present disclosure are directed to charged particle beam systems and components, algorithms, and methods for their operation. In particular, some embodiments are directed to techniques for heating a specimen. [Background technology]

[0003] In charged particle microscopy, characteristic X-rays are produced by excitation of core electrons as the beam interacts with atoms in the sample. X-ray signals are typically used for elemental analysis in scanning electron microscope (SEM) systems. For example, the X-ray signal can be used to generate an energy dispersive X-ray (EDS) spectrum, from which the elemental composition of the sample can be determined.

[0004] X-ray measurements are sensitive to EM radiation (e.g., infrared-visible photons), which can produce artifacts in EDS detector data. This presents a challenge when the thermal properties of materials are studied using EDS and other thermal-photon sensitive techniques. Therefore, there is a need for improved sample heating systems that can be used with EDS detectors. Summary of the Invention

[0005] In a first aspect, a heating assembly includes a membrane. The membrane can include a carbon nanotube material. The heating assembly includes a support mechanically coupled to the membrane. The support can be configured to integrate with a charged particle beam system. The heating assembly also includes a heating circuit electrically coupled to the membrane. The heating circuit can be configured to direct a current through the membrane.

[0006] In some embodiments, the membrane defines a shape including a taper. The taper may be defined in a plane in Cartesian coordinate space. The shape may include a double taper in the plane, such that a central region of the membrane is narrower than a peripheral region of the membrane. The heating assembly may be configured to operably couple to a sample stage of a charged particle beam system and to have a sample disposed thereon. The support may include a conductive portion in electrical contact with the membrane and electrically coupled to a heating circuit. The heating circuit may be configured to direct a current through the membrane via the conductive portion. The support may be shaped to operably couple to an electron microscope sample holder. The heating circuit may include a probe. The probe may be configured to electrically couple to the membrane or the support. The probe may be a first probe, and the heating circuit may further include a second probe reversibly coupled to the membrane, whereby a current is directed from the first probe to the second probe through the membrane. The membrane may be at least partially freestanding across an opening defined in the support. The carbon nanotube material may include a multi-walled carbon nanotube felt. The membrane can include multiple layers of carbon nanotube material. In some embodiments, the heating circuit includes a probe. The probe can be electrically coupled to a conductive portion of the membrane or the support. The probe can be mechanically coupled to an actuator and can be movable in one or more spatial dimensions. The probe can include a tip configured to interface with the membrane. The tip can include carbon nanotube material, can include filaments or other fibers that result in a brush-like structure, and / or can be flexible.

[0007] In a second aspect, a charged particle beam system includes a charged particle beam source, a sample chamber coupled to the charged particle beam source, and a heating assembly disposed within the sample chamber. The heating assembly may include one or more features of the preceding aspects, alone or in combination. For example, the heating assembly may include a membrane including a carbon nanotube material and a support mechanically coupled to the membrane, the support being reversibly coupled to a sample stage of a charged particle beam system and configured to have a sample disposed thereon and be irradiated by a charged particle beam generated by the charged particle beam source. The heating assembly may also include a heating circuit electrically coupled to the membrane and the charged particle beam system and configured to direct a current through the membrane. The heating circuit may be at least partially external to the sample chamber. For example, one or more components of the heating circuit may be external to the sample chamber and electrically coupled to one or more components within the sample chamber. In some embodiments, the system may further include a separation chamber. The separation chamber may include a fluid handling coupler and a deposition substrate. The deposition substrate may include a resistive heating circuit. The separation chamber can define an opening co-located with the deposition substrate. The separation chamber can be disposed within the sample chamber. The opening can be aligned with the charged particle beam source. A heating assembly can be disposed at least partially within the separation chamber. The heating assembly can be disposed within the separation chamber between the fluid handling coupler and the deposition substrate.

[0008] In a third aspect, a method for heating a sample includes directing a current through a membrane of a heating assembly of one or more of the preceding aspects. Directing a current through the membrane can include applying a power through the membrane of about 30 W or less, about 20 W or less, about 10 W or less, about 5 W or less, about 4 W or less, about 3 W or less, about 2 W or less, about 1 W or less, about 0.5 W or less, about 0.4 W or less, about 0.3 W or less, about 0.2 W or less, and / or about 0.1 W or less, including fractions, subranges, or interpolations thereof.

[0009] In some embodiments, the film can have a sample disposed thereon. The method can further include removing material from the film in a region of the film surrounding the sample and contacting the film with a probe electrically coupled to a heating circuit. The probe can contact the film in a region surrounding the sample. Removing material can include irradiating the film using a beam of charged particles, using mechanical force, using directed EM radiation, and / or by igniting an arc or other discharge between the probe and the film.

[0010] The method can include heating the film to a temperature higher than a vaporization or sublimation temperature of the sample. The temperature can be determined at least in part based on a pressure in the separation chamber and a composition of the sample. The method can include heating a deposition substrate. The deposition substrate can be heated to a substrate temperature lower than a vaporization or sublimation temperature of the sample. The method can include directing a beam of charged particles and / or a beam of photons toward the deposition substrate. The method can include exposing the deposition substrate to charged particles of the charged particle beam and generating a deposition material on the deposition substrate. The charged particle beam can be directed using a scanning pattern. The deposition material can be disposed on a surface of the deposition substrate according to the scanning pattern. The method can also include introducing a carrier gas into the separation chamber.

[0011] The terms and expressions which have been employed are used as terms of description and not as terms of limitation, and in using such terms and expressions there is no intention to exclude any equivalents of the features or portions thereof shown and described, but it is understood that various modifications are possible within the scope of the claimed subject matter. Thus, while the subject matter claimed herein has been specifically disclosed by embodiments and optional features, it should be understood that modifications and variations of the concepts disclosed herein may be made by those skilled in the art, and that such modifications and variations are deemed to be within the scope of the present disclosure as defined by the appended claims. [Brief explanation of the drawings]

[0012] 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, in which: [Figure 1A] FIG. 1 is a schematic diagram illustrating an exemplary charged particle beam system, in accordance with some embodiments of the present disclosure. [Figure 1B] 1B is a schematic diagram illustrating the operation of the exemplary charged particle beam system of FIG. 1A as a scanning electron microscope, including various detectors, in accordance with some embodiments of the present disclosure. FIG. [Figure 2A] FIG. 1 is a schematic diagram illustrating an exemplary heating assembly, according to some embodiments of the present disclosure. [Figure 2B] FIG. 1 is a schematic diagram illustrating an exemplary heating assembly, according to some embodiments of the present disclosure. [Figure 2C] FIG. 1 is a schematic diagram illustrating an exemplary heating assembly, according to some embodiments of the present disclosure. [Figure 2D] FIG. 1 is a schematic diagram illustrating an exemplary heating assembly, according to some embodiments of the present disclosure. [Figure 2E] FIG. 1 is a schematic diagram illustrating an exemplary heating assembly, according to some embodiments of the present disclosure. [Figure 2F] FIG. 1 is a schematic diagram illustrating an exemplary heating assembly, according to some embodiments of the present disclosure. [Figure 2G] FIG. 1 is a schematic diagram illustrating an exemplary heating assembly, according to some embodiments of the present disclosure. [Figure 2H] FIG. 1 is a schematic diagram illustrating an exemplary heating assembly, according to some embodiments of the present disclosure. [Figure 3] FIG. 1 is a schematic diagram illustrating an exemplary charged particle beam system, in accordance with some embodiments of the present disclosure. [Figure 4] FIG. 1 is a schematic diagram illustrating an exemplary heating assembly, according to some embodiments of the present disclosure. [Figure 5] FIG. 1 is a schematic diagram illustrating an exemplary charged particle beam system, in accordance with some embodiments of the present disclosure. [Figure 6] FIG. 1 is a schematic block flow diagram illustrating an exemplary method for localized heating of a material specimen, according to some embodiments of the present disclosure. [Figure 7A] 1A-1C are schematic diagrams illustrating exemplary configurations of one or more probes for heating a material sample, according to some embodiments of the present disclosure. [Figure 7B] 1A-1C are schematic diagrams illustrating exemplary configurations of one or more probes for heating a material sample, according to some embodiments of the present disclosure. [Figure 7C] 1A-1C are schematic diagrams illustrating exemplary configurations of one or more probes for heating a material sample, according to some embodiments of the present disclosure. [Figure 8A] 1 is an electron micrograph image showing heating of an exemplary material sample according to some embodiments of the present disclosure. [Figure 8B] 1 is an electron micrograph image showing heating of an exemplary material sample according to some embodiments of the present disclosure. [Figure 9A] 1 is an electron micrograph image showing localized heating of an exemplary material sample, according to some embodiments of the present disclosure. [Figure 9B] 1 is an electron micrograph image showing localized heating of an exemplary material sample, according to some embodiments of the present disclosure. [Figure 10A] 1 is an electron micrograph image showing localized heating of an exemplary material sample, according to some embodiments of the present disclosure. [Figure 10B] 1 is an electron micrograph image showing localized heating of an exemplary material sample, according to some embodiments of the present disclosure. [Figure 11] FIG. 1 is a schematic diagram illustrating an exemplary system for charged particle beam-induced deposition, according to some embodiments of the present disclosure.

[0013] In the drawings, like reference numbers refer to like parts throughout the various views unless otherwise specified. Not every instance of an element is necessarily labeled, to reduce clutter in the drawings where necessary. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles being described. DETAILED DESCRIPTION OF THE INVENTION

[0014] While exemplary embodiments have been described, it will be understood that various modifications are possible without departing from the spirit and scope of the present disclosure. The following paragraphs describe embodiments of analytical instrument systems, components, and methods for heating a sample. For ease of explanation, embodiments of the present disclosure focus on charged particle beam microscopy and microanalysis and related instrumentation. To that end, the embodiments are not limited to such instrumentation, but rather are contemplated for analytical instrumentation systems in which the analysis and temperature-dependent behavior of materials can be complicated by the relative dominance of characteristic thermal radiation arising from heat sources near the sample. In an exemplary example, X-ray microanalysis can include generating detector data using a sensor sensitive to infrared photons emitted by a heating stage, which act as noise that impairs X-ray signal quality. Such techniques can benefit from improved heating assembly structures and configurations to reduce the flux of infrared radiation reaching the detector. Furthermore, while embodiments of the present disclosure focus on electron beam systems, additional and / or alternative instruments and modalities are contemplated, including, but not limited to, ion beam systems, photon beam (e.g., laser) systems, and the like.

[0015] Embodiments of the present disclosure include systems, methods, algorithms, and non-transitory media storing computer-readable instructions for heating a sample. In an illustrative example, a heating assembly can include a membrane comprising carbon nanotube material, a support mechanically coupled to the membrane and configured to integrate with a charged particle beam system, and a heating circuit electrically coupled to the membrane and configured to direct current through the membrane. Advantageously, embodiments of the present disclosure reduce the thermal mass of the heating element, thereby reducing the flux of infrared radiation reaching the detector due to the heating assembly, while maintaining transparency to X-ray radiation, thereby filtering radiation leaving the sample and further reducing infrared artifacts in X-ray detector data. Additional advantages of the present disclosure include, but are not limited to, improved dynamic response, improved localization of heating to individual samples, compatibility with multiple samples, compatibility with multiple different charged particle beam systems, improved manufacturability for alternative heating sources (e.g., MEMS-based heating assemblies), and compatibility for use with beam-induced deposition techniques (e.g., electron beam-induced deposition (EBID) and / or ion beam-induced deposition (IBID)).

[0016] 1A is a schematic diagram illustrating an exemplary charged particle beam system according to some embodiments of the present disclosure. The exemplary charged particle microscope 100 includes multiple sections, including an electron source, a beam column 105, and a vacuum chamber 110. The electron source includes high-voltage supply components, vacuum system components, and an electron emitter configured to generate an electron beam that is accelerated into the beam column 105. The beam column 105, in turn, includes electromagnetic lens elements configured to shape and form the electron beam from the electron source into a substantially circular beam having a substantially uniform profile across the beam axis A, and adjust the beam by an objective lens 115 so that the beam is focused onto a sample 125, as described in more detail with reference to FIG. 1B.

[0017] Electron beams are typically characterized by, among other criteria, the beam current and acceleration voltage applied to generate the beam. The range of beam current and acceleration voltage can vary between instruments and is typically selected based on the material properties of the sample or the type of analysis being performed. Generally, however, in scanning electron microscopes, electron beams are characterized by energies of about 0.1 keV to about 50 keV (e.g., for an acceleration voltage of 0.1 kV) and beam currents in the picoampere to microampere range.

[0018] The vacuum chamber 110 and / or the beam column 105 can include multiple detectors for various signals, including, but not limited to, secondary electrons generated by the interaction of the electron beam with the sample, X-ray photons (e.g., EDAX), other photons (e.g., visible and / or IR cameras), and / or molecular species (e.g., TOF-SIMS), as described in more detail with reference to FIG. 1B . The vacuum chamber 110 can also include a sample stage 120 that can be operably coupled to a multi-axis translation / rotation control system to reposition the sample 125 relative to the beam axis A for investigating and / or imaging the sample 125. As described in more detail with reference to FIG. 4A , the sample stage 120 can include, be electrically coupled to, and / or mechanically coupled to a heating assembly 121. The heating assembly 121 can include components and / or materials that allow the transmission of charged particles and / or other radiation (e.g., X-rays) through the sample and / or the structure on which the sample is disposed (e.g., the membrane 210 of FIG. 2B ). In this manner, one or more charged particle and / or radiation sensors of the present disclosure may be disposed within the vacuum chamber 110 and / or within the beam column 105 and configured to detect characteristic signals emitted (e.g., reflected and / or transmitted) from the sample, as described in more detail with reference to Figures 2A-2H. In this manner, the heating assembly 121 may be configured to be operatively coupled to the sample stage 120, including electrical coupling (e.g., via a thermoelectric control system) and mechanical coupling (e.g., for translating and / or tilting the heating assembly using a stage control).

[0019] The exemplary charged particle microscope 100 is illustrated as a single-beam SEM instrument to focus the discussion on applications of the charged particle beam system of the present disclosure. In some embodiments, the charged particle microscope 100 can incorporate an ion beam source (e.g., a focused ion beam, or FIB, as part of a dual-beam system) adapted, for example, to modify a sample or for microanalysis. Similarly, the charged particle microscope 100 can include a photon source, such as a laser or other electromagnetic radiation source. In this manner, the charged particle sensor of the present disclosure can be configured to generate detector data (e.g., images, line scans, X-ray spectra, etc.) in conjunction with an ion source used for sample modification and / or microanalysis. In an illustrative example, a focused ion source (e.g., a p-FIB, etc.) can be operably coupled to the vacuum chamber 110 and configured to incrementally remove portions of the sample 125 layer by layer. During the increments, X-ray microanalysis of the sample 125 provides a depth profile of elemental information within the sample 125, which can be useful for quality assurance in semiconductor applications as well as other fields.

[0020] 1B is a schematic diagram illustrating the operation of the exemplary charged particle beam system of FIG. 1A as a scanning electron microscope, including various detectors, such as a mirror detector (MD) 155, a pole-piece detector (PMD), and a hologram detector (HVD) 160, according to some embodiments of the present disclosure. mounted detector (PMD) 160, EDS compatible STEM mode detector (STEM mode detector, SMD) 165, and through-the-lens detector Other detectors include a charge-dispersive detector (TLD) 170 and an Everhart-Thornley detector 175. Other detectors and sources that can be coupled to the vacuum chamber 110 include a conventional X-ray detector 130 (e.g., a silicon drift detector configured for energy dispersive X-ray spectroscopy). Embodiments of the present disclosure include charged particle microscopes that include X-ray sources, X-ray detectors, ion beam sources, mass spectrometers, light sources (e.g., laser sources), or other sources that would be included in the complement of analytical instruments available for use in SEM microanalysis. At least some of the detectors of the exemplary microscope 100 can be paired with filters proximate to or covering the absorbing surface of the detector, as described in more detail with reference to FIGS. 2A-3C.

[0021] As illustrated, the mirror detector 155 and the TLD detector 170 are disposed within the beam column 105 or the objective lens 115. For example, the mirror detector 155 can be disposed above the objective lens 115 and oriented with its sensor surface facing the sample stage 120. Advantageously, the location of the MD 155 within the beam column 105 makes it well-suited for a substantially flat sample 125 or a sample where the sample stage 120 can be reoriented so that the vertical angle is substantially aligned with the beam axis A, because in such cases, the angular distribution of the BSE 180 radiation is highest at a 45-degree angle relative to the surface of the sample 125. The MD 155 is illustrated without a retaining member or other support structure in FIG. 1B to focus the discussion on the relative position of the MD 155 with respect to the BSE 180, microscope 100 components, and sample 125. In some embodiments, the MD 155 is mounted on a retractable support 195, as illustrated for the SMD 165. In this manner, MD 155 can be introduced into a predetermined position within beam column 105 and / or objective lens 115 and then retracted from that position when the BSE 180 imaging / analysis mode is initiated by a user of charged particle microscope 100. In some embodiments, MD 155 is mechanically coupled to beam column 105 and / or objective lens 115 components and remains in a fixed position when not in use.

[0022] Pole piece-mounted detector 160 is mechanically coupled to pole piece 117 that houses objective lens 115 and can be oriented with its collector surface facing sample stage 120. Like MD 155, PMD 160 can be mounted on a retractable support 195 instead of being mechanically coupled to pole piece 117. Advantageously, mounting PMD 160 on a retractable support 195 allows PMD 160 to be removed from between sample stage 120 and pole piece 117, thereby allowing other probes, sources, or components (e.g., parabolic mirrors used for luminescence measurements and / or imaging) to be introduced into the space.

[0023] The adapted STEM mode detector 165, configured as an energy dispersive X-ray spectroscopy (EDS) detector, can be mechanically coupled to a retractable support 195 configured to introduce the SMD 165 into a position such that the sample stage 120 is between the objective lens 115 / pole piece 117 and the SMD 165. The SMD 165 can be oriented so that the detector surface faces the underside of the sample stage 120. In this manner, X-rays 181 emanating from the sample 125 (e.g., from the region of the sample's interaction volume where X-rays are generated) can reach the detector surface and generate a characteristic signal used for imaging and / or microanalysis. The X-rays 181 can include X-rays generated from inner-shell excitation of atoms in the sample 125, which are directed through the sample rather than back toward the beam column 105. Forward-scattered electrons (FSEs) emanating from the sample 125 can be absorbed by a heated assembly membrane characterized by a relatively low electron transmittance before reaching the detector surface and generating artifacts in the data (e.g., background signal). In some embodiments, the membrane can be thin enough to allow some transmission of the FSE, thereby enabling STEM-mode imaging and / or microanalysis of the sample. The membrane thickness can be determined at least in part based on the transmittance of the membrane material as a function of thickness for a given energy range of the FSE.

[0024] X-ray detector 130 includes detector 131 shielded from charged particles, photons, and other noise sources by window 133 and collimator 135, the collective result of which is a significant reduction in the volumetric collection angle. Additionally, to protect the window material and / or to reduce interactions between magnetic components of X-ray detector 130 and the charged electron beam, X-ray detector 130 may be limited to a relatively low take-off angle, e.g., about 30 degrees to about 50 degrees, measured from a plane defined by sample 125. The take-off angle can be increased by tilting sample 125, at the expense of reducing the functionality of detectors 155, 160, 165, and 170 during X-ray collection.

[0025] FIG. 2A is a schematic diagram illustrating an exemplary heating assembly 200 according to some embodiments of the present disclosure. The heating assembly 200 includes a membrane 210 within a support 215. The support 215 includes one or more contacts 220. The contacts 220 can operably couple (e.g., thermally, mechanically, etc.) the membrane 210 and / or the support 215 to one or more coupling members 225 that can operably couple the heating assembly 200 with a sample stage (e.g., the sample stage 120 of FIGS. 1A-1B). The membrane 210 includes multiple layers 211 of filter material, as described in more detail with reference to FIG. 2B. The support 215 can be coupled to the membrane 210 over at least a portion of its periphery. In this manner, the support 215 mechanically supports the membrane 210, allowing the membrane 210 to be at least partially self-supporting across the area of ​​the heating assembly 200. In the illustrated example, the support 215 forms a frame over which the membrane 210 extends, the membrane 210 being free-standing above an opening defined by the frame. Advantageously, placing the sample on the region of the heating assembly 200 such that the sample is supported by the membrane 210 allows the sample to be heated by the membrane and irradiated by the beam of charged particles to generate a detectable characteristic signal.

[0026] Embodiments of the present disclosure can be configured to be operably coupled to a charged particle beam instrument. For example, the coupling member 225 can include an electrical coupler, a mechanical coupler, an optical coupler, etc. to facilitate integration of the heating assembly 200 with a sample stage of a charged particle beam system. In the example of an SEM system, the coupling member 225 can include two electrical contacts configured to electrically couple with elements of a heating circuit and one or more mechanical couplings (e.g., clips, tab-and-slot couplings, etc.) to mechanically hold the heating assembly in place while coupled to the sample stage. In this manner, the heating assembly 200 can be moved using the stage control of the SEM system to direct current through the membrane 210.

[0027] The film 210 can include a material that exhibits selective transmissivity to X-rays 275. Selective transmissivity refers to the film 210 allowing at least a portion of incident X-rays 275 of a given energy to pass through the film 210 while absorbing relatively low-energy photons (e.g., UV-visible-IR photons) below a given threshold energy and absorbing or reflecting at least a portion of the electrons incident on the film 210. For example, the film 210 can absorb, reflect, or otherwise block substantially all electrons having an energy of about 7.8 keV or less. In some embodiments, the threshold energy can be selected at least in part based on filter thickness and / or filter density as parameters. For example, a filter having a thickness of about 2 um can block incident electrons having an energy below about 2.5 keV. While below 7.8 keV, the thickness dependence of filter performance allows for tuning of operating conditions. Furthermore, the threshold energy can depend at least in part on the composition of the film 210. For example, a film 210 comprising multi-walled carbon nanotubes can be characterized by a higher threshold energy compared to a film 210 comprising single-walled carbon nanotubes based at least in part on the mass density of the film 211. Similarly, a film 210 having a relatively high density of nanotubes per unit surface area can be characterized by a higher threshold energy than a film 210 having a relatively low density of nanotubes per unit surface area.

[0028] In illustrative embodiments, areal density is defined as the mass of membrane 210 material per unit surface area (e.g., square centimeter). The properties of membrane 210 can be described and / or related in terms of areal density based at least in part on characteristic volumetric properties, including the volume density (e.g., mass per volume) of the carbon material and / or the membrane's porosity (e.g., the average fraction of empty space within the membrane). In some embodiments, the volume density of the carbon material is about 0.11 g / cm 3 ~Approx. 1.1g / cm 3and includes subrange fractions and interpolations therein. In some embodiments, transparency and thickness are inversely related. For example, for a given areal density, a film thickness of about 1.32 μm can correspond to a transmittance at 550 nm of about 3.5%, while a film thickness of about 2.64 μm can correspond to a transmittance of about 0.12%. In this way, for a given film, both film thickness and transparency can be translated into areal density. For example, an areal density of about 0.1 μg / cm 2 ~About 330mg / cm 2 , including subranges, fractions, and interpolations thereof, allowing the dimensions of film 210, the number of layers, and the thickness of each individual layer to be determined based at least in part on a balance between transparency and dimensional / spatial constraints.

[0029] In some embodiments, the membrane 210 includes a carbonaceous material 213. The carbonaceous material 213 can include carbon nanotube materials. The carbon nanotube materials can include single-walled nanotubes, double-walled nanotubes, multi-walled nanotubes, and / or mixtures thereof. The carbonaceous material 213 can include carbon nanofibers, nanotubes, sp 2 Hybridized carbon, sp 3Other forms of hybrid carbon and / or mixtures thereof (e.g., a combination of graphite and amorphous carbon) may be included. The nanotubes, nanofibers, and / or nanofibers may be oriented along one or more in-plane directions and / or may be randomly oriented. For example, film 210 may include a layer in which the carbon nanotubes comprising the carbon nanotube felt are substantially aligned with the orientation direction. Different layers may be oriented in the same direction or different directions. While substantially aligned with the orientation direction on a given layer and / or film 210, individual nanotubes, nanofibers, etc. may exhibit twisting (e.g., curvature, angulation / kinking, looping, and / or helical twist segments) such that segments of a given nanotube, nanofiber, etc. may be oriented away from the orientation direction. Film 210 may further include metal, ceramic, and / or nitride materials, for example, as coatings, inclusions, or other forms that do not substantially limit the permeability and / or thermal properties of film 210.

[0030] Film 210 can have a thickness on the order of about 10 nm to about 10 μm (e.g., about 10 nm to about 99 μm), including subranges (e.g., about 0.5 μm to about 30 μm), fractions, and interpolations thereof. Film 210 can include multiple layers 211 of carbon nanotube material, each about 3 nm to about 1 μm thick, including subranges, fractions, and interpolations thereof. In one example, each layer can have a thickness of about 0.4 μm, such that a film having two layers of carbon nanotube material can be about 0.8 μm thick, and a film having 25 layers of carbon nanotube material can be about 10 μm thick. Without being bound by any particular physical phenomenon or mechanism, filter 210 can have a thickness-dependent transmittance based at least in part on the absorbance of each constituent layer. In this manner, the film 210 may include several layers that allow the filter 210 to absorb substantially all incident photons and / or charged particles while allowing a significant portion of the X-rays 275 to pass through.

[0031] Each layer can have a photon absorption (e.g., measured at 525 nm) of about 1% to about 90%. In an example of a 25-layer carbon nanotube material, with each layer having about 40% absorbance at 525 nm, the overall absorption coefficient of film 210 for photons at 525 nm is about 1×10 -9 In an example embodiment of the membrane 210 having a thickness of about 2 um, the transmittance of Li Kα (55 eV) X-rays 275 can be about 23%, corresponding to a significant improvement over current bulk heating stages that are opaque to X-rays. Furthermore, current technology comparative detectors that include carbon materials as part of the window layer typically include a support grid that introduces artifacts and a light-shielding aluminum coating on at least one surface of the window layer, which further reduces the quantum efficiency of the detector. In contrast, membranes of the present disclosure can include an at least partially unsupported membrane 210 held by a frame (e.g., support 215 in FIG. 2A ) around at least a portion of the membrane 210.

[0032] 2B shows that the membrane 210 can be electrically coupled to the electronic components of the heating circuit 230 via contacts 220. For example, the membrane 210 can form electrical contact with the contacts 220. The electronic components can include one or more power sources 235. The heating circuit 230 can be at least partially external to the sample chamber (e.g., the vacuum chamber 110 of FIGS. 1A-1B). For example, one or more components of the heating circuit can be external to the sample chamber and electrically coupled (e.g., by electrical feedthroughs) to one or more components inside the sample chamber.

[0033] In this manner, an electrical potential (e.g., a voltage) can be applied across the membrane, thereby directing an electrical current through the membrane and inducing resistive heating. Advantageously, forming membrane 210 with or from carbon nanotube material can improve the performance of heating assembly 200 as a heating stage while preserving the ability of the heating assembly to store and / or detect characteristic signals from a sample disposed on membrane 210.

[0034] In this context, the performance of the heating assembly 200 as a heating stage for sample microanalysis refers, at least in part, to one or more properties of the membrane 210 as a resistive heating element 240. For example, the resistive heating element 240 can be characterized by dynamic characteristics (e.g., rise time) and material properties (e.g., thermal mass). The electrically conductive carbon nanotube material is characterized by improved thermal radiation properties relative to comparable resistive heating materials, such as carbon fiber materials and tungsten-based materials, allowing the exemplary heating assembly 200 to generate relatively less thermal radiation (e.g., infrared-visible photons) than other materials at comparable temperatures and reach a set-point temperature in a relatively short time. Advantageously, the relatively low thermal radiation allows the heating assembly of the present disclosure to be smaller than conventional bulk heating stages in which the membrane 210 is heated instead of a bulk material. This reduces the heated thermal mass and allows heating rates of up to approximately 10,000 Kelvin per second. This represents a significant improvement over the heating rates of conventional bulk heating stages.

[0035] 2C-2H are schematic diagrams illustrating several exemplary configurations of the membrane 210 of the exemplary heating assembly 200, according to some embodiments of the present disclosure. The shape of the membrane 210 in one or more spatial dimensions can affect the behavior and performance of the membrane 210 as a heating element. Without being bound to a particular physical mechanism, the power dissipated in the membrane 210 can be a function of the current directed through the membrane 210 and the voltage drop across the membrane 210. The heat generation at a given location within the membrane 210 is a flux quantity, and therefore the local temperature of the membrane 210 can be related to the power dissipated within the membrane 210 and the geometric cross-section of the membrane at a given location. In this way, the temperature can be localized for a given current, with narrower portions of the membrane 210 being hotter than wider portions of the membrane 210.

[0036] To that end, FIG. 2C illustrates an exemplary membrane 210 defining a shape that includes a taper 245. The taper may be defined in a plane in Cartesian coordinate space. In the example of FIG. 2C, the taper 245 is defined in an XY Cartesian plane such that the width of the membrane 210 in the "Y" dimension can be expressed as a function of position in the "X" dimension. The letters "X" and "Y" are used for convenience and do not refer to true horizontal or vertical directions. The shape may include multiple taper angles, an example of which is shown in FIG. 2C, and thus the shape may include a number of sides ranging from three to twenty or more. For example, a four-sided tapered membrane may define a trapezoidal shape, but FIG. 2C illustrates a double taper in the plane such that a central region 250 of the membrane 210 is narrower than a peripheral region 255 of the membrane 210.

[0037] In some embodiments, the membrane 210 defines a shape that includes tapers defined in multiple planes. The shape can include tapers in the XY and XZ planes in Cartesian space. In the exemplary embodiment shown in FIG. 2D , the shape of the membrane 210 includes a three-dimensional taper from a first cross-sectional area in the YZ plane near the support portion 220 to a second, relatively smaller cross-sectional area in the YZ plane near a central region of the membrane 210. Similar to the tapered shape described with reference to FIG. 2C , a flux of electrons passing through the membrane can heat the central region 250 to a relatively higher temperature than the peripheral regions 255. As described in more detail with reference to Examples 1-3, the membrane 210 can be repeatedly heated to a temperature at which a sample 260 disposed on the membrane 210 can undergo a phase transition. In this context, the term “phase transition” can refer to a change from a solid phase to a liquid phase (e.g., melting), but can also refer to other types of phase transitions, such as temperature- and / or pressure-dependent crystalline phase structures. In illustrative examples, a crystalline sample can be heated to induce a transition from a first crystalline phase to a second crystalline phase, and the transition between phases can be imaged using SEM (e.g., BSE channeling contrast) / FIB, or electron microscopy techniques (e.g., e-beam diffraction, X-ray spectroscopy, etc.). Advantageously, the heating assembly of the present disclosure allows one or more physical phases and / or phase transitions to be investigated under charged particle irradiation. The membrane 210 exhibits improved heating characteristics and substantial transparency to characteristic signals generated by the interaction of the sample 260 with the charged particle beam 190.

[0038] 2E-2H illustrate alternative exemplary embodiments including openings 265 formed in the film 210, whereby current flow can be directed through the film 210 to produce relatively high temperatures in localized regions of the film 210. Advantageously, defining one or more openings 265 in the film 210 can improve the structural stability of the film while imparting improved heating behavior (e.g., by reducing the effective cross-sectional area of ​​the film 210). Furthermore, defining the cross-section as a function of position within the film 210 by patterning the openings 265 in the film 210 can improve manufacturability and / or enable in situ preparation of the film 210 in the presence of the sample 260. In an exemplary embodiment, a beam of charged particles (e.g., ions, electrons, etc.) and / or photons (e.g., a laser) can be directed toward the film 210 to pattern the openings 265, as described in more detail with reference to FIG. 6 .

[0039] 3 is a schematic diagram illustrating an exemplary charged particle beam system according to some embodiments of the present disclosure. In the following description, details of the internal components and functions of an exemplary TEM system 300 are omitted for simplicity and to focus the description on embodiments of the present disclosure, as described in more detail with reference to FIG. 4. The exemplary TEM system 300 includes an electron source section, a TEM column including a sample section 305, and an imaging section 310. The present disclosure focuses on techniques for improving the performance of a heating assembly for use in the sample section 305.

[0040] Briefly, the electron source section includes electronics configured to energize a source of charged particles, which may include a high-voltage field source or other source of emitted electrons, such that a beam of electrons is formed and conducted through a vacuum to the TEM column. The TEM column includes beam-forming components, including electromagnetic and / or electrostatic lenses, and multiple apertures for controlling the characteristics of the electron beam. TEM column components include a condenser lens, an objective lens, a projector lens, an aberration corrector, a deflector, an astigmatism corrector, etc., and corresponding apertures. The sample section 305 houses the sample 260 (see FIG. 2A ), positioned on a heating assembly through which the electron beam can be transmitted, as described in more detail with reference to FIG. 4 . The sample section can include one or more types of detectors, such as an X-ray detector, a secondary electron detector, etc.

[0041] A modern TEM column can have as many as four focusing lenses for flexible (e.g., step-wise or gradually varying) demagnification and concentration of the electron beam on the sample, as many as five projection lenses for flexible expansion of the electron beam downstream of the sample relative to the detector, and as many as two aberration correctors. Because modern aberration correctors can include additional lenses and several multipoles (e.g., four lenses and two to three or more multipoles), a modern TEM column can contain up to about 20 lenses. The coordinated action of the collection of lenses and other optical elements produces a given demagnification at the sample and magnification at the detector.

[0042] The detector section 310 includes one or more types of detectors, sensors, screens, and / or optics configured to generate images, spectra, and other data for use in sample imaging and / or microanalysis. For example, the imaging section may include, among other things, a scintillator screen, binoculars, a transmission electron microscope (TEM) detector (e.g., a pixelated electron detector, a secondary electron detector, a camera, a segmented STEM detector, and an electron energy loss spectroscopy (EELS) spectrometer 315. The EELS spectrometer 315 functions at least in part as an energy filter by focusing the electron beam onto an electrostatic or magnetic dispersive element (also referred to as a "prism") that exerts a force on the electrons proportional to their velocity. In this way, electrons that have transferred energy to the sample (e.g., by inelastic collisions) can be redirected through the magnetic dispersive element to the detector. The detector may include a pixelated detector (e.g., a CCD device configured to detect electrons) that generates one- or two-dimensional EELS data, from which an EELS spectrum can be extracted. In some embodiments, the EELS spectrometer 315 also includes one or more optical elements, such as electromagnetic or electrostatic lenses, and / or multipoles and / or accelerators, to condition or focus the scattered electrons onto the detector.

[0043] FIG. 4 is a schematic diagram illustrating an exemplary heating assembly 400, according to some embodiments of the present disclosure. The exemplary heating assembly represents one embodiment of the exemplary heating assembly 200 described with reference to FIGS. 2A-2H, where the heating assembly 400 is shaped to operably couple with a TEM sample holder 405. To that end, the exemplary heating assembly 400 includes one or more membranes 410 and one or more frames 415 including one or more conductive portions 420. The conductive portions 420 can electrically couple the frame 415 to components of a heating circuit (e.g., as described with reference to FIG. 2B) configured to interface the frame 415 with the sample holder 405 and / or other components of a TEM system (e.g., the exemplary system 300 of FIG. 3). In the illustrative example, electrical coupling between the frame 415 and the heating circuit can be facilitated by forming one or more conductive contacts 430 on the frame 415 and using one or more conductive probes 435.

[0044] The frame 415 may be or include a TEM grid or components of a TEM grid, such that conventional TEM grid holders can be adapted for use with the heating assembly 400. Where conventional heating holders include electrical contacts, traces, etc. such that sample placement locations are relatively limited to the heating location, the membrane 410 of the present disclosure can allow for relatively unrestricted sample placement, facilitated by probe positioning when the probe is electrically coupled to the membrane 410, as described in more detail with reference to Figures 6-7C. In this manner, the heating assembly of the present disclosure allows the sample 460 to be heated individually.

[0045] Advantageously, integration of the disclosed heating assembly into a TEM / STEM instrument can enable the generation of detector data at levels of spatial resolution beyond those available in SEM instruments. Furthermore, TEM / STEM analysis enables crystal structure analysis of the nanostructured sample 460, allowing temperature-dependent properties of the sample 460 to be investigated at the nanoscale. To that end, embodiments of the present disclosure include a membrane 410 that is substantially transparent to electrons (e.g., above a given threshold energy) and substantially transparent to x-rays (e.g., outside one or more characteristic energies associated with the membrane material).

[0046] FIG. 5 is a schematic diagram illustrating an exemplary charged particle beam system according to some embodiments of the present disclosure. The exemplary system 500 includes an instrument 505 (e.g., the exemplary system 100 of FIGS. 1A-1B), an instrument computing device (IPC) 510, and a client computing device 515 operably interconnected via one or more networks 520. The exemplary system 500 includes a probe assembly 530 electronically coupled to components of a heating assembly 525 via a heating circuit (e.g., as described with reference to FIGS. 2A-2H). The instrument 505 includes a test section 545 in which the probe assembly 530 is disposed, including vacuum components for isolating the heating assembly 525 from the atmosphere. A charged particle column 540 and one or more detectors 550 are coupled to the test section. The charged particle column 540 can be an ion beam (e.g., a focused ion beam (FIB)) column or an electron beam column. In some embodiments, the instrument 505 includes a FIB column and an electron beam column, and one of the charged particle sources is coupled to the vacuum chamber at an angle to the charged particle column.

[0047] The electron beam column may generate a beam of electrons 547 and focus the beam of electrons 547 onto the heating assembly 525. Interaction of the beam of electrons 547 with the heating assembly 525 produces one or more detectable signals that may be received by one or more detectors 550 operably coupled to the vacuum chamber 545 and configured to generate detector data based at least in part on measurements of the signals. In one illustrative example, the detectors 550 may include a secondary electron detector, a backscattered electron detector, a photon detector, an imaging sensor (e.g., a CCD), an X-ray detector, or the like.

[0048] A typical scanning electron microscope In contrast to conventional scanning electron microscopes (SEMs), the vacuum chamber 545 can omit sample manipulation tools such as interlocks and sample stages, at least in part because the heating assembly 525 can be removably coupled to a probe assembly 530, which can be disposed on a stage, cradle, or other holding assembly that provides electronic and thermal coupling with the test section. A beam of electrons 547 can be directed toward the heating assembly 525 using various modes of operation, including, but not limited to, an imaging mode, a line-scan mode, and a spot mode. The probe assembly 530 can include individually addressable probes 555 that are movable in three spatial dimensions (labeled "x, y, and z" Cartesian axes) by electromechanical actuators 560. In this manner, the probe tips can be displaced toward locations on the surface of the heating assembly 525 with nanometer-scale precision. In some embodiments, the probe assembly 530 is electronically coupled to components of the test section 535 via couplings 565 and 570, thereby enabling the actuators 560 to be driven (e.g., using drive signals) and output signals to be generated.

[0049] Computing devices 510 and 515 may be general-purpose machines (e.g., laptops, tablets, smartphones, servers, etc.) configured to operate or otherwise interact with instrument 505. Instrument 505, in turn, may include electronic components forming part of a dedicated computing device, including control circuitry configured to drive the test loop, actuate probe assembly 530, control electron beam column 540, and operate the vacuum system and thermal management system. IPC 510 may be a machine with software configured to interface with instrument 505 and enable a user of instrument 505 to perform tests of heating assembly 525. Similarly, client PC 515 may be configured to control one or more systems of instrument 505 (e.g., by interfacing with instrument 505 via IPC 510 and / or via network 520) to perform tests of heating assembly 525. In some embodiments, the instrument 505, IPC 510, and / or client PC 515 are in separate physical locations and are coupled via a network 520 and / or by other means such as a direct connection or by a wireless connection (e.g., short-range wireless). The network 520 can include a public network (e.g., the Internet) and / or a private network (e.g., an intranet or local area network). In some embodiments, the IPC 510 and / or client PC 515 are configured to operate the instrument autonomously (e.g., without human intervention) or semi-autonomously (e.g., with limited human intervention, such as initiating tests, identifying samples, and / or confirming automated analysis results).

[0050] FIG. 6 is a schematic block flow diagram illustrating an exemplary process for localized or partially localized heating of a material sample, according to some embodiments of the present disclosure. One or more operations of the exemplary process 600 may be performed by a computer system in communication with additional systems, including, but not limited to, instrument systems, network infrastructure, databases, and user interface devices. In some embodiments, at least a subset of the operations described with reference to FIG. 6 are performed automatically (e.g., without human involvement) or quasi-automatically (e.g., with human initiation or limited human intervention). In exemplary examples, operations for positioning a probe tip, displacing the probe tip, generating and / or directing a beam of charged particles, isolating a sample, and directing a current through a heating assembly may be performed automatically or quasi-automatically. While the exemplary process 600 is described as a series of operations, it is understood that at least some of the operations may be omitted, repeated, and / or reordered. In some embodiments, the operations of exemplary process 600 are preceded and / or followed by additional operations omitted for clarity of explanation, such as operations for electron source calibration, electron beam alignment and aberration correction, initializing probe position, etc. In this context, "localized" and "partially localized" refer to the use of one or more movable electrical contacts (e.g., probes 555 in FIG. 5 ) to direct current to a membrane (e.g., membrane 210 in FIG. 2A ) proximate to the sample. In this manner, current can be directed through the membrane from the movable electrical contacts to a conductive portion of the heating assembly (e.g., conductive portion 220 in FIG. 2A ) and / or from one movable contact to another.

[0051] In operation 605, the exemplary process 600 includes identifying a sample. Identifying the sample can include one or more sub-operations directed to locating a sample (e.g., sample 260 in FIGS. 2A-2H) disposed on a membrane (e.g., membrane 210). Identifying the sample can include image processing sub-operations that can include human intervention, automated edge-finding and / or feature-tracking algorithms, thereby localizing the sample on the membrane. In this regard, the image can include various detector data (e.g., secondary electron image data, backscattered electron image data, optical camera image data, etc.) generated by the charged particle beam system.

[0052] In operation 610, the exemplary process 600 includes directing charged particles toward the film 210. Charged particles in the context of operation 610 can include electrons and / or ions. In some embodiments, the stream of charged particles can degrade or otherwise remove material of the film 210 at predetermined locations on the film 210. To do so, the stream of charged particles can be directed toward the film using a beam of charged particles (e.g., generated using an SEM or other charged particle beam system) and / or by biasing a probe 555 relative to the film (or vice versa) to induce a current between the probe 555 and the film 210.

[0053] In operation 615, the example process 600 includes removing material from the film 210 to at least partially isolate the sample 260 on a portion of the film 210 based at least in part on forming one or more openings 640 in the film 210 (e.g., an example of opening 265 in FIGS. 2E-2H ). Isolating the sample 260 may include patterning the film by translating a probe 555 or by modifying a scan control signal (e.g., associated with a scan circuit, such as in the example system 100 of FIG. 1 , the example system 500 of FIG. 5 , etc.) such that charged particles are incident on the film 210 at multiple locations along a path 635. For example, the probe 555 may be biased relative to the film such that an electric current may be used to locally ablate the film and form the openings 640 (e.g., by igniting an arc, a pulsed arc, etc.).

[0054] To that end, operations 610 and 615 of exemplary process 600 may be parallelized and / or serialized in multiple iterations. For example, a beam of charged particles (e.g., beam 547 of FIG. 5 ) may be steered across the surface of film 210 along path 635 such that a stream of primary electrons may be used to form opening 640. In this manner, a region 645 of film 210 around sample 260 may be at least partially isolated and used for localized electrical heating of film 210 and sample 260. In some embodiments, operation 615 may also include mechanically carving opening 640 using probe 555 and / or ablating film material using an EM radiation source (e.g., a laser, a pulsed laser, etc.).

[0055] In operation 620, the example process 600 includes positioning a probe 555 to form electrical contact with the membrane 210 within a peripheral region 645 defined by the opening 640. While the probe 555 is shown as a defining conical shape, embodiments of the present disclosure include probes 555 of additional or alternative geometric shapes. For example, the probe tip can define an irregular, branched, brush-like, or otherwise structured shape to reduce the likelihood of the probe 555 penetrating the membrane 210 rather than forming a durable electrical contact. In some embodiments, the probe 555 includes surface roughness and relatively high flexibility as ways to improve the quality of contact with the membrane 210.

[0056] In operation 625, the exemplary process 600 includes directing a current through the membrane 210 using a probe 555 to localize the current through a peripheral region 645. In this manner, the region 645 is heated to a relatively high temperature compared to the membrane material outside of the region 645. When a single probe 555 is used to direct a current through the membrane 210, the current can be directed between the probe 555 and one or more conductive portions (e.g., portion 220 of FIG. 2A ) of a support element of a heating assembly (e.g., the exemplary heating assembly 200 of FIG. 2A , the exemplary heating assembly 400 of FIG. 4 , the exemplary heating assembly 525 of FIG. 5 , etc.). As described in more detail with reference to FIGS. 7A-7C , the number and relative positions of the probe tips 555 and openings 640 can vary.

[0057] Advantageously, the exemplary process 600 allows for localized heating of an individual sample 260 on a membrane 210 that may otherwise support one or more other samples, as shown in Figure 4. As such, a single sample preparation and loading procedure can be used to prepare multiple replicate microanalytical experiments, thereby improving throughput and efficiency in terms of preparatory operation time and complexity.

[0058] 7A-7C are schematic diagrams illustrating exemplary configurations of one or more probes for heating a material sample, according to some embodiments of the present disclosure. An exemplary embodiment of a membrane including a multi-probe configuration and multiple openings 640 is shown. In FIG. 7A, two probes (e.g., probe 555 of FIG. 5) are electrically coupled to membrane 210 near sample 260 and used to confine a portion of membrane 210 through which current is directed. In this manner, an operation for removing membrane material can be omitted in at least some iterations of exemplary processes of the present disclosure (e.g., exemplary process 600 of FIG. 6). In FIG. 7B, the techniques described with reference to FIGS. 2C-2H can be adapted to define a peripheral region 645 near the sample, and the pattern defined as part of exemplary process 600 (e.g., in operations 610 and 615 of FIG. 6) can include multiple openings 640 that at least partially separate both the sample and peripheral region 645 from one or more conductive portions of a heating assembly support structure (e.g., support 215 of FIG. 2A, portion 220 of FIG. 2A, etc.). In Figure 7C, multiple conductive paths are defined using multiple probes 555 electrically coupled to the membrane 210. Multiple apertures 640 are used to define peripheral regions of the membrane. Advantageously, the illustrated multi-path configuration allows for subtle dynamics and a level of spatially localized heating to be applied to the sample, for example, if the membrane 210 and / or sample exhibits anisotropic conductivity / resistivity or other thermal and / or electrical properties. For example, a four-probe configuration allows for resistance measurements of the region defined by the apertures 640, from which the temperature of the membrane can be inferred.

[0059] Example 1: Localized heating of various material samples The following paragraphs describe experimental data generated using the disclosed system. The images below represent detector data revealing the solid-to-liquid phase transition of various metal particles disposed on a film through which a current was directed to induce heating. The data indicate that the film was heated to a point where the metal melted and became liquid or amorphous, at least in the vicinity of the sample. Experimental conditions included a film of multiwalled carbon nanotubes and DC power of about 3 to about 5 watts for non-localized heating to about 1350 K (e.g., as depicted in Figures 2A-2H), and about 0.2 W to about 0.6 W for localized or partially localized heating to comparable temperatures (e.g., as depicted in Figures 6-7C). The experiment duration was about 30 seconds, and the film's heat-up time was significantly shorter, heating from about 300 K to about 1300 K in about 0.1 seconds.

[0060] 8A-8B are electron micrograph images showing heating of an exemplary material sample according to some embodiments of the present disclosure. The sample included gold and was characterized by a melting temperature of 1337 K under conditions in the SEM. Thus, the film was capable of reversibly heating the sample to temperatures above 1337 K using electrical heating induced by passing an electric current through the film.

[0061] 9A-9B are electron micrograph images showing localized heating of an exemplary material sample according to some embodiments of the present disclosure. The sample comprises silicon and was characterized by a melting temperature of 1687 K under conditions in the SEM. In this manner, the film was capable of reversibly heating the sample to temperatures above 1687 K using electrical heating induced by passing an electric current through the film. The experiment from which the data in FIGS. 9A-9B were collected included performing at least some of the operations of exemplary process 600 of FIG. 6 , whereby a peripheral region of the film was defined near the sample and a probe tip was used to direct a heating current through the film. The phase transition of silicon is manifested in the formation of a smooth surface and the collection of the sample material into a spherical shape, consistent with the physical tendency to minimize surface energy in liquids.

[0062] 10A-10B are electron micrograph images showing localized heating of an exemplary material sample according to some embodiments of the present disclosure. The sample included platinum and was characterized by a melting temperature of 2041 K under conditions in the SEM. In this manner, the film was capable of reversibly heating the sample to temperatures above 2041 K using electrical heating induced by passing an electric current through the film. The experiment from which the data in FIGS. 9A-9B were collected included performing at least some of the operations of exemplary process 600 in FIG. 6 , whereby a peripheral region of the film was defined near the sample and a probe tip was used to direct a heating current through the film. The deformation of the film observed in FIG. 10B is due to the surface tension effect of the platinum, which forms droplets (e.g., minimizes surface energy) while remaining wet on the surface of the film.

[0063] Example 2: Generation of precursor vapors for EBID / IBID procedures FIG. 11 is a schematic diagram illustrating an exemplary system 1100 for charged particle beam-induced deposition according to some embodiments of the present disclosure. The exemplary system 1100 includes a separation chamber 1110 for containing vapor generated by heating a sample material 1120 using a heating assembly 1125 of the present disclosure. A carrier gas can be introduced via a conduit 1115 fluidly coupled to the chamber. The carrier gas can entrain the vaporized sample and direct the vapor into the vicinity of a deposition substrate 1130. A charged particle beam 1135 (e.g., an ion beam, an electron beam, etc.) and / or a photon beam (e.g., a laser) can be directed toward the deposition substrate 1130 to induce a deposition process in which the vapor acts as a deposition precursor. Such techniques can be used to deposit a pattern of material 1140. The deposition material 1140 can be chemically identical, similar, or different from the sample material from which the precursors were generated. For example, multiple precursors can be generated using one or more heating assemblies of the present disclosure such that the beam-induced deposition process involves a chemical reaction of the precursors to generate a solid deposition material. In some cases, the deposition process uses the energy of the beam to induce the deposition process (e.g., when inert ions such as argon or xenon are used). Advantageously, the heating assembly of the present disclosure provides improved performance, such as heating time, energy efficiency, and geometric size constraints, allowing for miniaturization of the system 1100 and integration into the disclosed charged particle beam systems. Furthermore, the composition of the deposition material 1140 can be adjusted by adjusting the operation of the heating assembly 1125 (e.g., by adjusting the current directed through the membrane 1127). In some embodiments, detector data 1145 can be generated from the interaction of the charged particle beam 1135 with the deposition substrate 1130 (e.g., secondary electrons 1147), thereby enabling control of the deposition process.

[0064] The system 1100 enables chemical vapor deposition using precursor materials that cannot be delivered near the deposition substrate 1130 using standard devices for gas delivery (e.g., gas injection needle systems), at least in part because such materials tend to condense in supply lines and on other surfaces at relatively low temperatures (typically room temperature or below 200°C). Precursor materials, such as perovskites, tellurium, selenides, and sulfur, can be placed in close proximity to the deposition substrate 1130 and heated to induce vaporization and / or sublimation. To do so, the heater 1125 for the precursor material 1120 can be maintained at a temperature higher than the temperature of the deposition substrate 1130 (typically in the range of about 400°C to about 1500°C). The deposition substrate 1130 can be heated to a temperature of about 100°C to about 1200°C.

[0065] Thermal radiation generated by the heating assembly 1125, which may be the hottest part of the system 1100, can impair the performance of SEM detectors (155, 160, 175), which may be sensitive to IR radiation and light emitted by the heated parts. The heating assembly 1125 can be shaped to minimize the power required for precursor material evaporation. For example, the shaping techniques described in Figures 6 and 7 can be used to localize heating near the precursor material 1120. Heater shaping is possible before (e.g., when precise sample placement is performed) and / or after placing the precursor material 1120 on the heater 1125 prior to an in situ deposition experiment, when at least a portion of the separation chamber 1110 (e.g., a cover portion) can be removed to allow access to the heater 1125 for the FIB or manipulator needle used for shaping. In some cases, some of the thermal radiation generated by the heating assembly 1125 can be absorbed by the deposition substrate 1130, affecting local temperature and heating control stability. Advantageously, the heating assembly of the present disclosure is characterized by approximately an order of magnitude lower thermal radiance (e.g., dissipating approximately 4 W as opposed to approximately 40 W for a typical bulk heating stage), significantly reducing the impact on the temperature of the deposition substrate 1130 and improving the accuracy, stability, and precision of thermal control of the deposition substrate 1130.

[0066] Various embodiments have been described in the preceding specification. For purposes of explanation, specific configurations and details have been set forth to provide a thorough understanding of the embodiments. However, it will be apparent to those skilled in the art that the embodiments may be practiced without the specific details. Furthermore, well-known features may be omitted or simplified so as not to obscure the described embodiments. While the exemplary embodiments described herein center around charged particle beam systems, specifically electron microscope systems, these are meant to be non-limiting exemplary embodiments. Embodiments of the present disclosure are not limited to such embodiments, but rather are intended to be directed to analytical instrument systems capable of analyzing a wide range of material samples to determine chemical, biological, physical, structural, or other properties, including, but not limited to, chemical structure, trace element composition, and the like, among other aspects where temperature dependence is of interest.

[0067] Some embodiments of the present disclosure include a system including one or more data processors and / or logic circuitry. In some embodiments, the system includes a non-transitory computer-readable storage medium including instructions that, when executed on the one or more data processors and / or logic circuitry, cause the one or more data processors and / or logic circuitry to perform some or all of one or more methods and / or some or all of one or more processes or workflows disclosed herein. Some embodiments of the present disclosure include a computer program product tangibly embodied in a non-transitory machine-readable storage medium including instructions configured to cause one or more data processors and / or logic circuitry to perform some or all of one or more methods and / or some or all of one or more processes disclosed herein.

[0068] The terms and expressions which have been employed are used as terms of description and not as terms of limitation, and in using such terms and expressions there is no intention to exclude any equivalents of the features or portions thereof shown and described, but it is understood that various modifications are possible within the scope of the claims. Thus, while the present disclosure includes specific embodiments and optional features, it should be understood that modifications and variations of the concepts disclosed herein can be made by those skilled in the art, and that such modifications and variations are considered to be within the scope of the appended claims.

[0069] When a term is used without an explicit definition, it should be understood that the ordinary meaning of the word is intended unless the term has a special and / or specific meaning in the field of charged particle microscope systems or other related fields. The terms “about” or “substantially” are used to indicate a deviation from a described characteristic, where the deviation has little or no effect on the corresponding function, characteristic, or attribute of the described structure. In an illustrative 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 may not be equal within acceptable limits, such as manufacturing tolerances or confidence intervals inherent in the operation of the system. Similarly, when a geometric parameter such as alignment or angular orientation is described as “about” perpendicular, “substantially” perpendicular, or “substantially” parallel, the term “about” or “substantially” is intended to reflect that the alignment or angular orientation may differ from the strictly described condition (e.g., not be strictly perpendicular) within acceptable limits. With respect to numerical values ​​such as diameter, length, width, etc., the term “about” can be understood to describe a deviation of up to ±10% from the described value. For example, a dimension of "approximately 10 mm" can describe a dimension between 9 mm and 11 mm.

[0070] This specification provides exemplary embodiments and is not intended to limit the scope, applicability, or configuration of the present disclosure. Rather, the description of the exemplary embodiments that follows will provide those skilled in the art with an enabling description for implementing various embodiments. It will be understood that various changes can 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 provided herein 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 disclosure may be shown in schematic diagram form or omitted from illustrative views so as 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

1. 1. A heating assembly comprising: a membrane comprising a carbon nanotube material; a support mechanically coupled to the membrane, the support configured to be integrated with a charged particle beam system; a heating circuit electrically coupled to the membrane and configured to direct an electrical current through the membrane; A heating assembly comprising:

2. The assembly of claim 1 , wherein the membrane defines a shape that includes a taper, the taper being defined in a plane in Cartesian coordinate space.

3. The assembly of claim 2 , wherein the shape includes a double taper in the planar surface such that a central region of the membrane is narrower than a peripheral region of the membrane.

4. The assembly of claim 1 , wherein the heating assembly is operatively coupled to a sample stage of the charged particle beam system and configured to have a sample placed thereon.

5. 2. The assembly of claim 1, wherein the support includes a conductive portion in electrical contact with the membrane and electrically coupled to the heating circuit, the heating circuit configured to direct the current through the membrane via the conductive portion.

6. The assembly of claim 1 , wherein the support is shaped to operably couple with an electron microscope sample holder.

7. The assembly of claim 1 , wherein the heating circuit comprises a probe, the probe configured to be electrically coupled to the membrane or the support.

8. 8. The assembly of claim 7, wherein the probe is a first probe and the heating circuit further comprises a second probe reversibly coupled to the membrane, whereby the current is directed from the first probe to the second probe through the membrane.

9. The assembly of claim 1 , wherein the membrane is at least partially self-supporting across an opening defined in the support.

10. The assembly of claim 1 , wherein the carbon nanotube material comprises a multi-walled carbon nanotube felt.

11. The assembly of claim 1 , wherein the membrane comprises multiple layers of carbon nanotube material.

12. 1. A charged particle beam system comprising: a charged particle beam source; a sample chamber coupled to the charged particle beam source; a heating assembly disposed within the sample chamber, the heating assembly comprising: a membrane comprising a carbon nanotube material; a support mechanically coupled to the membrane, the support being reversibly coupled to a sample stage of the charged particle beam system, the support configured to allow a sample to be placed thereon and irradiated by a charged particle beam generated by the charged particle beam source; a heating assembly comprising: a heating circuit electrically coupled to the membrane and the charged particle beam system and configured to direct a current through the membrane; A charged particle beam system comprising:

13. 13. The charged particle beam system of claim 12, wherein the support includes a conductive portion electrically coupled to the membrane and electrically coupled to the heating circuit, the heating circuit configured to direct the current through the membrane via the conductive portion.

14. The system of claim 12 , wherein the support is shaped to mechanically couple with an electron microscope sample holder.

15. The system of claim 12 , wherein the heating circuit comprises a probe, the probe being electrically coupled to a conductive portion of the membrane or the support.

16. 13. The system of claim 12, further comprising a separation chamber comprising a fluid handling coupling and a deposition substrate, the heating assembly being disposed within the separation chamber between the fluid handling coupling and the deposition substrate.

17. 1. A method for heating a sample, the method comprising: directing an electric current through a membrane of a heating assembly, said heating assembly comprising: the membrane comprising carbon nanotube material, the sample being disposed on the membrane; a support mechanically coupled to the membrane, the support being reversibly coupled to a sample stage of a charged particle beam system; a heating circuit electrically coupled to the membrane and the charged particle beam system and configured to direct an electric current through the membrane.

18. 20. The method of claim 17, wherein directing the current through the membrane comprises applying a power of about 30 W or less through the membrane.

19. The membrane has a sample disposed thereon, and the method comprises: removing material from the film in a region of the film surrounding the sample; 18. The method of claim 17, further comprising contacting the membrane in the region around the sample with a probe electrically coupled to the heating circuit.

20. 20. The method of claim 19, wherein removing the material comprises irradiating the film with a beam of charged particles.

Images