Patent Application
20230095798
The present description relates generally to methods and systems for determining sample composition, and more particularly, to mapping elements in the sample using a charged particle microscope.
Charged particle microscopy is a well-known and increasingly important technique for imaging microscopic objects. Multiple types of emissions from a sample responsive to charged particle irradiation may provide structural and compositional information of the sample. For example, based on energy spectrum of an X-ray emission responsive to electron beam irradiation, energy-dispersive X-ray spectroscopy (EDS or EDX) can be used for elemental analysis or chemical characterization. However, Applicant recognizes that some of the light elements are hard or impossible to be detected with EDS.
In one embodiment, a method comprises scanning a region of interest (ROI) of a sample with an electron beam and acquiring X-rays emitted from the sample; after scanning the ROI with the electron beam, scanning the ROI with an ion beam and acquiring ion-induced photons emitted from the sample; and determining a spatial distribution of multiple elements in the sample based on both the acquired X-rays and the acquired ion-induced photons. In this way, spatial distribution of elements that cannot be detected by EDS may be mapped based on ion beam induced light emission.
In another embodiment, a charged particle microscopy system for determining composition of a sample comprises an ion source for generating an ion beam; an electron source for generating an electron beam; a first detector for detecting X-rays emitted from a sample; a second detector for detecting ion-induced photons emitted from the sample; and a controller including a non-transitory memory for storing computer readable instructions, wherein by executing the instructions, the controller is configured to: scan a region of interest (ROI) of the sample with the electron beam and acquire X-rays emitted from the sample using the first detector; after scanning the ROI with the electron beam, scan the ROI with the ion beam and acquire ion-induced photons emitted from the sample using the second detector; and determine a spatial distribution of multiple elements in the sample based on both the acquired X-rays and the acquired ion-induced photons. In one example, the second detector is retractable from an imaging position at which the ion beam induced light emission is detected.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.
Like reference numerals refer to corresponding parts throughout the several views of the drawings.
The following description relates to systems and methods for determining composition of a sample. Sample composition may be determined via charged particle based spectroscopic techniques such as energy-dispersive X-ray spectroscopy (EDS or EDX) and secondary ion mass microscopy (SIMS). These spectroscopic techniques can be combined with scanning electron microscopy (SEM) or transmission electron microscopy (TEM) to provide co-registered compositional and structural information of the sample. However, some elements, especially light elements (i.e. element with atomic number not greater than 11), are hard or impossible to be detected by EDS or SIMS. For example, hydrogen cannot be detected by EDS, and is difficult to be detected by SIMS. EDS has low sensitivity to alkali metal such as lithium, and also to trace metal/element. Because understanding the spatial distribution of elements including H and Li may be critical for manufacturing and evaluating certain sample, such as the battery sample, there is a need for obtaining a complete elemental map of the sample. Further, SEM based techniques have difficulty to detect trace elements due to their large interaction volume, resolution limits, and lack of surface sensitivity.
Applicant recognizes that comparing to EDS and SIMS, ion beam induced light emission is more sensitive to heavy elements, alkali metal, and trace element. By scanning the sample with the electron beam before the ion beam, both X-ray emission and photon emission from the sample can be acquired. By combining information obtained from ion beam induced light emission with EDS, a complete elemental mapping of the sample may be generated.
In one example, a region of interest (ROI) of the sample is first scanned with an electron beam, and X-rays emitted from the sample are acquired. Then, the ROI is scanned with an ion beam, and photon emissions from the sample are acquired. Elements within the ROI of the sample surface may be determined by analyzing the acquired X-ray and optical spectra. Due to different sensitivities of the EDS and the ion beam induced light emission to different elements, more elements may be identified and mapped by combing the EDS with ion beam induced light emission. For example, the EDS detects elements with atomic number greater than 11 and the ion beam induced light emission detects elements with atomic number not greater than 11. The ion beam induced light emission detects alkali metal while the EDS detects non-alkali metal. The EDS detects an element at a higher weight concentration, while the ion beam induced light emission detects the element at a lower weight concentration. For example, the FIB-iLE may detect some element with a weight concentration lower than 100 ppm. The detection limit of the FIB-iLE is element dependent.
In some examples, the ion beam is a focused ion beam (FIB), and the ion beam induced light emission is herein also referred to as focused ion beam induced light emission (FIB-iLE). Due to the destructive nature of the ion beam scan, the sample surface is first scanned with the electron beam before being scanned with the ion beam, so that the same sample layer is analyzed by both EDS and FIB-iLE. Because the interaction volume of the electron beam with the sample is generally greater than the interaction volume of the ion beam, at each scan location, EDS signals may include information of a larger sample volume than the FIB-iLE signals. Therefore, the FIB-iLE imaging can achieve a higher resolution than the EDS imaging.
In one example, elemental composition of a first sample layer is determined based on signals acquired during the electron beam scan and the ion beam scan of a first sample surface. While scanning the first sample surface with the ion beam, the first sample surface is milled by the ion beam to expose a second sample surface at an increased sample depth. The second sample surface is scanned using the electron beam and the ion beam, and the elemental composition of the second sample surface is determined. The above procedures may be repeated for multiple iterations to reconstruct a three-dimensional elemental composition of the sample.
In some examples, one or more elemental maps showing distribution of multiple elements are generated based on the acquired X-rays and photon emissions. Spatial distribution of the multiple elements can be shown in a single elemental map by color-coding each element.
The combined EDS and FIB-iLE sample analysis may be performed in a charged particle microscope (CPM) shown in
In one example, the ion source is a liquid metal ion source (LMIS). In another example, the ion source is a plasma ion source capable of generating a focused ion beam of one or more gas species. Signal strength for FIB-iLE may be enhanced by adjusting the gas chemistry of the plasma ion beam. In one embodiment, scanning the ROI with the ion beam includes simultaneously directing ions of at least two species towards the sample surface. One of the at least two ion species may be lighter and more chemically active than the other ion species. In one example, the atomic number difference between the at least two ion species may be not less than 8. In another example, the atomic number difference between the at least two ion species may be not less than 10. The lighter ions (i.e. ions with lower atomic number) has a higher photon yield for FIB-iLE, while the heavier ions (i.e. ions with higher atomic number) has a higher sputter rate. By scanning the ROI with both the lighter ions and the heavier ions, the FIB-iLE signal is enhanced and at the same time, sample can be removed at high sputter rate. In another embodiment, scanning the ROI with the ion beam including first scanning selected regions within the ROI with a lighter ion to implant the lighter ion in the sample, and then scanning the ROI with a heavier ion for FIB-iLE signal acquisition. By implanting the lighter, chemically active ion, in selected regions within the ROI, the photon yield in these selected regions during the following ion beam scan with the heavier, inert ion, can be enhanced.
The second, FIB-iLE, detector may include a light collection system retractable from the vacuum chamber within which the sample is imaged. The light collection system may include an optical fiber with a first distal end enclosed in an elongated sheath. A lens is optically coupled to the first distal end of the optical fiber for directly collecting photons emitted from the sample. The lens is mechanically coupled to the sheath. Light emitted from the sample is collected by the FIB-iLE detector when the detector is positioned at an imaging position, wherein the first distal end of the detector is positioned between a pole piece (either the pole piece of the ion column or the electron column) and the sample. The FIB-iLE detector may be inserted to the imaging position and/or retracted from the imaging position via a flange on the vacuum chamber of the charged particle microscope. Due to the compact profile of the FIB-iLE detector, alternating EDS and FIB-iLE sample scan may be performed without retracting the FIB-iLE detector from the imaging position. In some examples, the FIB-iLE detector may be retracted from the imaging position during sample maneuver and/or for detector maintenance.
The FIB-iLE detector may be used for detecting photon emission responsive to irradiations other than ion beam. For example, photon emissions responsive to electron beam or light irradiation can also be collected with the FIB-iLE detector. The FIB-iLE detector may be introduced into the vacuum chamber of a charged particle microscope compatible with a gas injection system (GIS), via the same flange for the GIS system. As such, photon detection can be achieved without significant system modification. The FIB-iLE detector may also be used for delivering light towards the sample.
In one example, a method for detecting photon emissions responsive to charged particle or photon irradiation using the FIB-iLE detector comprises: before pumping down a vacuum chamber within which the sample is positioned, inserting the light collection system of the FIB-iLE detector into the vacuum chamber via an opening on the vacuum chamber; pumping down the vacuum chamber; irradiating the sample with the charged particle beam or photons; and receiving photon emissions from the sample via the light collection system positioned at the imaging location. The status of the lens or lens system of the light collection system may be determined by monitoring the signal attenuation of the detected photons overtime. The lens or lens system may be replaced or cleaned after a period of use based on the status.
Turning to
The electron column 1 comprises an electron source 10 and an illuminator 2. The illuminator 2 comprises lenses 11 and 13 to focus the electron beam 3 onto the sample 6, and a deflection unit 15 (to perform beam steering/scanning of the beam 3). The microscope 100 further comprises a controller/computer processing apparatus 26 for controlling inter alia the deflection unit 15, lenses 11, 13 and detectors 19, 21, and 41, and displaying information gathered from the detectors 19, 21, and 41 on a display unit 27.
The detectors 19, 21 may be chosen from a variety of possible detector types that can be used to examine different types of “stimulated” radiation emanating from the sample 6 in response to irradiation by the (impinging) electron beam 3. It could alternatively be an X-ray detector, such as Silicon Drift Detector (SDD) or Silicon Lithium (Si(Li)) detector, for example. Detector 21 may be an electron detector in the form of a Solid State Photomultiplier (SSPM) or evacuated Photomultiplier Tube (PMT) for example. This can be used to detect backscattered and/or secondary electrons emanating from the sample 6. Microscope 100 may also include an ion detector and a mass analyzer for SIMS imaging. The skilled artisan will understand that many different types of detector can be chosen in a set-up such as that depicted, including, for example, an annular/segmented detector.
Detector 41 includes a retractable light collection system 42 for detecting photon emissions from sample 6. The photon emissions may be resulted from ion and/or electron beam irradiation on the sample surface. The light collection system 42 may be introduced to the vacuum chamber 5 via flange 52 on the vacuum chamber 5. Photons collected by the first distal end 51 of the light collection system 42 may be converted and amplified by an imaging sensor before transferring to controller 26. In some embodiment, the light collection system may also be used to deliver light towards sample 6. Detector 41 is herein referred to as FIB-iLE detector for detecting light emission responsive to FIB irradiation. However, detector 41 can also be used for detecting cathodoluminescence resulted from electron beam irradiation.
By scanning the beam 3 over the sample 6, stimulated radiation—comprising, for example, X-rays, infrared/visible/ultraviolet light, secondary electrons (SEs) and/or backscattered electrons (BSEs)— emanates from the sample 6. Since such stimulated radiation is position-sensitive (due to said scanning motion), the information obtained from the detectors 19, 21 and 41 will also be position-dependent.
The signals from the detectors (19, 21 and 41) pass along control lines (buses) 25, are processed by the controller 26, and displayed on display unit 27. Such processing may include operations such as combining, integrating, subtracting, false coloring, edge enhancing, and other processing known to the skilled artisan. In addition, automated recognition processes (e.g. as used for particle analysis) may be included in such processing. The controller includes a non-transitory memory for storing computer readable instructions, and a processor for executing the computer readable instructions. Methods disclosed herein may be implemented by executing the computer readable instructions in the processor.
In addition to the electron column 1 described above, the microscope 100 also comprises an ion column 31. This comprises an ion source 39 and an illuminator 32, and these produce/direct a focused ion beam (FIB) 33 along an ion-optical axis 34. To facilitate easy access to sample 6 on holder 7, the ion-optical axis 34 is canted relative to the electron-optical axis 101. As hereabove described, such ion column 31 can, for example, be used to perform processing/machining operations on the sample 6, such as incising, milling, etching, depositing, etc. Additionally, the ion column 31 can be used to produce imagery of the sample 6. It should be noted that ion column 31 may be capable of generating various different species of ion; accordingly, references to ion beam 33 should not necessarily been seen as specifying a particular species in that beam at any given time—in other words, the ion beam 33 might comprise ion species A for operation A (such as milling) and ion species B for operation B (such as implanting), where species A and B can be selected from a variety of possible options.
The microscope may include a Gas Injection System (GIS), which can be used to effect localized injection of gases, such as etching or precursor gases, etc., for the purposes of performing gas-assisted etching or deposition. Such gases can be stored/buffered in a reservoir and can be administered through a narrow nozzle, so as to emerge in the vicinity of the intersection of axes 101 and 34, for example. The GIS system may be introduced to vacuum chamber 5 via the same flange 52 as for introducing detector 41.
It should be noted that many refinements and alternatives of such a set-up will be known to the skilled artisan, such as the use of a controlled environment within (a relatively large volume of) the microscope 100, e.g. maintaining a background pressure of several mbar (as used in an Environmental SEM or low-pressure SEM).
In one example, the outer diameter of lens 204 matches the inner diameter of the sheath 201, so that the lens can be inserted into the lumen of the sheath 201. The outer diameter of the sheath 201 is greater than the outer diameter of the lens. At least a part of lens 204 is enclosed in the sheath. In another example, the lens may have an outer diameter the same as the outer diameter of the sheath 201. The lens may be fixed to the tip of the first distal end 208 with adhesive. The lens or lens system may be replaced or removed after a period of use to remove any contamination, such as deposition due to ion milling, on the surface of the lens.
In one example, the sample is tilted to face either the ion column or the electron column for the ion beam scan or the electron beam scan.
In one example, the sample may be tilted to face the electron beam or the ion beam between the scans. Each of the charged particle beams may irradiate the sample at 90-degree incidence angle for the scan. In another example, the sample may be held stationary relative to the ion and electron columns during the entire imaging session. Both the electron beam and the ion beam may scan the sample at an incidence angle less than 90 degrees.
At 301, the FIB-iLE detector may optionally be positioned in the vacuum chamber of the charged particle microscope. Positioning the FIB-iLE detector may include inserting the light collection system of the FIB-iLE detector into the vacuum chamber via the flange. Further, the first distal end of the light collection system may be positioned at the imaging position. The vacuum chamber may be pumped down after introducing the light collection system into the vacuum chamber.
At 302, the beam and scan parameters are optionally determined by performing a parameter optimization procedure on a sacrificial region of the sample or a reference sample. In one example, parameters for the ion beam scan are determined from a calibration table generated based on ion scans on multiple areas in the sacrificial region. Details of the parameter optimization procedure are shown in
At 304, system parameters are set for sample imaging. The system parameters may include one or more of beam current, beam size, beam energy, dwell time, integration time of the detector, and scan pattern for both the electron beam and the ion beam. The scan patterns for the electron beam scan and the ion beam scan may be different. The optimal beam and scan parameters determined at 302 may be used for the system parameters. Further, a ROI of the sample (i.e. ROI relative to the sample's coordinates) may be determined. The ROI may be determined based on SEM scans of the sample.
At 306, the ROI is scanned with the electron beam according to parameters set at 304, and X-ray emissions from each scanning location within the ROI are acquired using the EDS detector. During the scan, an image (such as SEM image) showing structural information of the sample surface may also be obtained by detecting backscattered electrons from the sample. In some examples, secondary ion emissions from the sample are acquired for SIMS.
At 308, the sample may optionally be tilted from the electron column towards the ion column.
At 310, method 300 checks whether the imaging session is finished. For example, progress of the image session can be determined based on the SEM image acquired at step 306. If the imaging session is complete, method 300 ends. Otherwise, the ROI is scanned with the ion beam at 312.
At 312, the ROI is scanned with the ion beam, and photon emissions at each scanning location are acquired using the FIB-iLE detector. The ion beam scan may be adjusted based on the configuration of the microscopy system and the sample type to enhance the FIB-iLE detection. In one example, scanning the ROI with the ion beam includes directing a single species of ions to each of the scanning locations. In another example, scanning the ROI with the ion beam including simultaneously directing ions of at least two species to each of the scanning locations. In yet another example, scanning the ROI with the ion beam including first directing ions of a first species towards each of the scanning locations, and then directing ions of a second species towards each of the scanning locations, wherein the photons are collected responsive to irradiating the sample with the second ion species. Details of the ion beam scan are presented in
At 314, one or more elemental maps of the sample surface are generated based on the acquired X-ray and photon emissions. The elemental map may show spatial distribution of multiple detected elements within the ROI. Each element may be color-coded differently in the elemental map. Secondary electron (SE) images responsive to the ion irradiation may simultaneously be acquired during the ion scan. The FIB induced SE (FIB-SE) image can show structures of the sample surface. In some examples, the elemental map may be combined with structural image acquired at 306 or the FIB-SE image to display both the structural and compositional information in a single image.
At 316, method 300 checks whether the imaging session is completed. In one example, the progress of the imaging session may be determined based on the structural and/or compositional images generated at step 306 and/or step 314. In another example, imaging session may be complete after reaching a predetermined sample depth or milled a predetermined number of sample layers. If the imaging session is complete, method 300 ends. If the imaging session is not complete, method 300 proceeds to 318 to adjust the electron beam and the ion beam for imaging a sample surface at a greater sample depth. The sample may also optionally be tilted at 320 before being scanned with the electron beam.
In this way, a complete elemental map of one or more sample surfaces/layers can be obtained by scanning the same ROI sequentially with the electron beam and the ion beam in a charged particle microscope. Different elements may be detected by EDS and the FIB-iLE.
In one embodiment, instead of or in addition to acquiring photons responsive to ion irradiation, secondary ions may be acquired for SIMS. The elemental information obtained from SIMS may be combined with the elemental information obtained via FIB-iLE and/or EDS to obtain the complete elemental mapping of the sample. In another embodiment, cathodoluminescence may be collected during the electron beam scan using the FIB-iLE detector.
In one example, optimal parameters for the FIB are determined for enhancing FIB-iLE and/or SIMS image quality. FIB is commonly used for milling a sample. However, the parameters used for FIB milling may not be optimal for FIB-iLE or SIMS. This is because the increased current density and/or the long dwell time used in FIB increase ion implantation and sample damage, but reduce the intrinsic photon or secondary ion yield. During the ion beam scan, the photon or secondary ion yield is affected by composition and structure of the sample, as well as condition of the microscopy system. For example, multiple factors including the matrix effects, preferential sputtering, and ion implantation affect the photon or secondary ion yield. As such, it is extremely difficult or impossible to determine the optimal beam and scan parameters for FIB-iLE or SIMS.
At 402, system parameters for the parameter optimization procedure are set. The system parameters may include one or more of the beam size, beam current, beam energy, dwell time, and scan areas. Further, a sacrificial region may be identified. The sacrificial region may be a sample region not overlapped with the ROI for combined EDS and FIB-iLE imaging. The sacrificial region may alternatively be a region on a reference sample.
At 404, the ion beam is directed towards an area in the sacrificial region.
At 406, one or more areas in the sacrificial region are irradiated using different beam or scan parameters of the ion beam, and photon and/or secondary electron yield is recorded. The calibration table may be generated based on the recorded yields at their corresponding beam/or scan parameters. In one example, generating the calibration table includes generating a photon yield versus beam flux plot at 408. Multiple calibration tables may be generated for various ion beam accelerating energies due to the change in implantation, damage, and sputtering rate at different energies. The generated calibration table(s) may be saved for determining the parameters in future imaging sessions.
One example calibration table is a photon yield versus beam flux plot shown in
In some example, plot similar to
At 412, the beam and scan parameters that are optimal for the FIB-iLE and/or SIMS imaging are selected based on the calibration table. For example, beam and scan parameters corresponding to the ion beam flux within range 501 of
In some examples, a trained neural network (NN) may be used to determine the optimal beam and scan parameters from calibration data collected in a sacrificial region. The NN may be trained with training data generated through finding the optimal imaging conditions for a sample type. For example, the training data may consist of photon yield as function of ion dose to a sample area, similar to the plot shown in
Different ions interact with the sample differently. For example, heavy ions (i.e. ions with atomic weight greater than 11), such as Xe+, have smaller interaction volumes in the sample and promote sputtering. Signals generated from heavy ions contain mainly elemental line emission. Light ions (i.e. ions with atomic weight not greater than 11), such as He+ and O+, have larger interaction volumes in the sample and promote electron-hole recombination. Signals generated from light ions contain band-gap and crystal information.
At 602, signal enhancement method for the ion beam scan is selected based on one or more of sample composition, sample property, and parameters of the microscope. For example, the signal enhancement method may be selected based on one or more of the materials of the sample, the oxygen replenishment rate of the sample within the vacuum chamber of the microscope, and requirements of the sample analysis. The oxygen replenishment rate may be determined at 302 of
At 604, selected regions within the ROI are scanned first with a lighter, more active, ion type to precondition the sample surface by implanting the lighter ions. The regions within ROI may be selected based on the SEM image collected during the electron beam scan at 306. Then, at 606, the ion source is switched from the lighter ion type to a heavier, more inert, ion type to scan the entire ROI. Photon emissions are acquired during the scan using heavier ions. In one example, the atomic number difference between the lighter and heavier ions is greater than 10. By implanting light ions in one or more sub-areas of the ROI, FIB-iLE signals in these selected regions may be enhanced. The selected regions may include elements having lower photon yield. By selectively enhancing FIB-iLE signals within these regions, the signal-to-noise ratio of the entire ROI can be improved in the FIB-iLE image acquired at 606. Further, by limiting regions for light ion implantation, sample damage and/or chemical altering of the sample surface may be minimized. In some embodiments, at 606, additionally, or alternatively, to acquiring photon emissions, secondary ions may be acquired during the scan using heavier ions.
At 608, the photons are acquired responsive to scanning the ROI with an ion beam including at least two ion species. Different from 604 and 606, wherein the sample surface is first scanned with a lighter ion species then a heavier ion species, herein, ions of multiple species are simultaneously directed to the sample surface. In one example, the ion beam includes a lighter ion species and a heavier ion species. The atomic weight difference between the two ion species may be not less than 8, 10, or 20. The acquired photon emissions include both narrow band elemental line emission from light ion bombardment and broadband electron-hole recombination from heavy ion bombardment. By irradiating the sample surface simultaneously with both light and heavy ions, the FIB-iLE and/or SIMS signals are enhanced while maintaining minimal reduction to the sputtering rate. Comparing to the ion beam scan using only the heavy ion, the FIB-iLE and/or SIMS signal is stronger. Comparing to the ion beam scan using only the light ion, the delayering (or sputtering) rate is higher.
At 610, photons are acquired responsive to irradiating the sample with ion beam of a single ion type.
In this way, the FIB-iLE signals may be enhanced by using ions or multiple gas species. The SIMS signals may be enhanced via the same process.
The technical effect of performing the electron beam scan before the ion beam scan is that elements in the same sample layer can be analyzed. Further, a complete elemental map can be generated due to different sensitivities of FIB-iLE and EDS to different elements. The technical effect of optimizing the ion beam before the imaging session is to obtain high FIB-iLE signal at a desired sample sputtering rate. The technical effect of using the retractable light collection system for FIB-iLE imaging is that the light collection system can stay at the imaging position when switching the charged particle beams. Further, the retractable light collection system can be used a conventional dual-beam system. The technical effect of using multiple ion species together or sequentially during the ion beam scan is that the FIB-iLE signals are enhanced.
In one presentation, a light collection system for collecting light in response to charged particle irradiation, comprises an optical fiber with a first distal end enclosed in an elongated sheath; a lens positioned at a first distal end of the light collection system, wherein the lens is optically coupled with the optical fiber for directly collecting light emitted from a sample responsive to the charged particle irradiation, and the lens is mechanically coupled to the sheath, and wherein the light collection system is retractable from an imaging position located proximate to a sample, the sample positioned on a sample stage in a vacuum chamber. In a first example of the system, the first distal end of the light collection system can be retracted from the imaging position wherein the first distal end of the light collection system positioned between a pole piece and the sample while in the imaging position. A second example of the system optionally includes the first example and further includes wherein the light collection system is retractable from the vacuum chamber via a flange. A third example of the system optionally includes one or more of the first to the second examples, and further includes wherein the diameter of the lens is equal or less than the diameter of the sheath. A fourth example of the system optionally includes one or more of the first to the third examples, and further includes wherein at least part of the lens is enclosed by the sheath. A fifth example of the system optionally includes one or more of the first to the fourth examples, and further includes wherein the lens includes multiple lenses of the same diameter. A sixth example of the system optionally includes one or more of the first to the fifth examples, and further includes wherein the lens focuses the beam into the optical fiber. A seventh example of the system optionally includes one or more of the first to the sixth examples, and further includes wherein the lens is fused with the first distal end of fiber. An eighth example of the system optionally includes one or more of the first to the seventh examples, and further includes wherein the lens is spaced from the first distal end of fiber, and the sheath has at least one opening fluidically connecting the vacuum chamber and the space between the fiber and the lens within the sheath. A ninth example of the system optionally includes one or more of the first to the eighth examples, and further includes wherein the lens is removable from the light collection system.
In another representation, a charged particle microscopy system includes an electron column, an ion column, and a detector for collecting photons generated in response to electron irradiation and/or ion irradiation. In a first example of the system, the detector includes a retractable light collection system. A second example of the system optionally includes the first example and further includes a vacuum chamber, wherein the light collection system can be retractably removed from the vacuum chamber via an opening on the vacuum chamber. A third example of the system optionally includes one or more of the first to the second examples, and further includes a GIS system, wherein the GIS system can be introduced into and removed from the opening on the vacuum chamber. A fourth example of the system optionally includes one or more of the first to the third examples, and further includes wherein the light collection system collects photons at an imaging position, and the collection angle of the light collection system at the imaging position does not overlap with the collection angle of other detectors of the microscopy system.
In yet another presentation, a method for collecting light emitted from a sample using a light detection system comprises, before pumping down a vacuum chamber within which the sample is positioned, inserting the light collection system via an opening on the vacuum chamber; irradiate the sample with charged particle beam or photon and receiving photons emitted from sample responsive to the irradiation with a first distal end of the light collection system at an imaging position. In a first example of the method, further includes monitoring signal attenuation over time and changing or cleaning a lens in the light collection system. A second example of the method optionally includes the first example and further includes delivering light towards the sample using the light collection system.
