Method for determining a virtual source position of a liquid metal ion source

Abstract

It is disclosed to determine changes in charged particle beam (CPB) source position by scanning an alignment aperture, particularly at the edge of a defocussed CPB illumination disk, the alignment aperture being fixed relative to a beam defining aperture in the CPB. The alignment aperture is operable to transmit a portion of the CPB to a secondary emission surface which generates a secondary emission directed to a scintillator element. Scintillating light generated in response is directed by a light guide out of a vacuum housing associated with the CPB to an external photodetection system.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to focused ion beam systems. BACKGROUND

[0002] Focused ion beams (FIB) can be directed at workpieces for workpiece evaluation, repair, and manufacturing. For many applications, high beam intensity is preferred to reduce processing time and increase throughput. Liquid metal ion sources (LMIS) are particularly attractive for generating FIBs because they can produce high beam currents. Unfortunately, ion beam emission from LMIS tends to emanate from an emission region whose position changes over time. Thus, a properly aligned ion beam source will often become misaligned. While the FIB column can be disassembled for realignment, such disassembly can be time consuming and requires venting of the vacuum chamber containing the LMIS and FIB column. After realignment and reassembly, the vacuum chamber must be pumped down before use. During this time, the FIB instrument is unavailable. In addition, venting can also result in contamination that must be eliminated before use. Alternative methods are needed for aligning beam sources in charged particle beam systems. SUMMARY

[0003] A charged particle beam alignment apparatus includes an alignment aperture plate defining an alignment aperture and a secondary emission element positioned to receive a portion of a charged particle beam (CPB) transmitted by the alignment aperture and operable to generate a secondary emission in response. A scintillator element is positioned to receive at least a portion of the secondary emission and generate scintillating light in response. A photodetector receives the scintillating light generated at the scintillator element. By moving the alignment aperture and detecting the scintillating light with the photodetector, the CPB axis can be located so that movement of the source can be compensated. In some examples, the scintillating light is coupled out of a vacuum enclosure with a light guide so that the photodetector is not within the vacuum enclosure.

[0004] The foregoing and other features and advantages of the present disclosure will become more apparent from the following detailed description, taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0005] Figures 1A-1B A representative alignment apparatus is shown.

[0006] Figure 2 A portion of another representative alignment apparatus is shown.

[0007] Figure 3 A representative focused ion beam (FIB) system including an alignment apparatus is shown.

[0008] Figure 4A A representative alignment method is shown.

[0009] Figure 4B Another representative alignment method is shown.

[0010] Figure 4C An alignment hole scan used in the method of Figure 4B is shown.

[0011] Figure 4D A plot of beam intensity as a function of scan position associated with a scan area as shown in Figure 4D is shown.

[0012] Figure 5A An alignment method based on detecting the edge of an illumination disc is shown.

[0013] Figure 5B An alignment method using a pixelated detector is shown.

[0014] Figure 6 A representative alignment apparatus including a photodetector is shown. DETAILED DESCRIPTION

[0015] The disclosed methods and apparatuses relate to the measurement of the source position (real or virtual) of a liquid metal ion source (LMIS) or other ion source, so that the ion beam optics provided in the ion beam column or the ion source position can be adjusted to maintain alignment. In some examples, such measurements are made periodically or as needed. In some cases, the ion source is repositioned to a previously established position, while in other cases, drive levels such as voltages applied to the charged particle beam (CPB) optical column are adjusted to compensate for the measured ion source position. Repositioning the ion source to a previously established position allows the ion beam to be aligned in a simple and straightforward procedure.

[0016] General terminology

[0017] As used herein, an ion beam column, electron beam column, or other charged particle beam (CPB) column is defined as one or more CPB optical elements, such as electrostatic or magnetic lenses, beam deflectors, beam limiting apertures, stigmators, apertures, or other beam shaping and beam directing elements. In these examples, the charged particle beam (CPB) column is sometimes divided into two or more sections. It is convenient to describe the CPB column as including an upper column in which charged particles from a source are shaped into a CPB using one or more optical elements, which can include one or more condenser lenses, stigmators, beam deflectors, and apertures. A lower column can include one or more lenses, stigmators, beam deflectors, and apertures, and is generally configured to shape and direct the CPB received from the upper column to a workpiece. In some examples, the lower column focuses the CPB to a point of a selected size at a selected location on the workpiece. The CPB column sits within a vacuum enclosure, which can define an upper chamber and a lower chamber in which the upper and lower columns, respectively, are located. The upper and lower chambers can be separated with an isolation valve, so that, for example, the upper column can remain operational during workpiece exchange in the lower chamber. This can reduce upper chamber contamination, pump down time, and allow for measurement and adjustment of the upper column during workpiece exchange.

[0018] As used herein, an Everhart-Thornley (ET) detector is a type of electron detector that includes a scintillator material coupled to a light guide so that scintillations (generally referred to herein as scintillation light) generated by charged particles at the scintillator material are at least partially directed to the light guide to propagate to a photodetector. In disclosed examples, the ET detector can include a plastic or glass light guide, a hollow light guide, a plastic or glass optical fiber, or other light guide. A typical light guide is depicted as having a circular cross-section, but the cross-section can be elliptical, oval, square, polygonal, or other shape. Circular cross-sections are convenient to manufacture, and such light guides are widely available. Scintillator materials, such as ceramic scintillators or dielectric scintillators (such as plastic scintillators), alkali halides, such as thallium-doped sodium iodide, denoted as NaI(Tl), thallium-doped cesium iodide, denoted as CsI(Tl), sodium-doped cesium iodide, denoted as CsI(Na), europium-doped lithium iodide, denoted as LiI(Eu); other inorganic materials, such as bismuth germanium oxide (Bi4Ge3O 12), commonly referred to as BGO, cadmium tungstate, denoted as CdW04, silver-doped zinc sulfide, denoted as ZnS(Ag); cerium-activated inorganics such as gadolinium oxyorthosilicate (GSO), yttrium aluminum perovskite (YAP), yttrium aluminum garnet (YAG), lutetium oxyorthosilicate (LSO), lutetium aluminum perovskite (LuAP), lanthanum bromide (LaBr); organic crystals such as anthracene can be used. Other types can also be used as can be necessary. The scintillator element can be provided as a cylinder, a cube, a sheet, a disc, a plate, a powder, a crystal section, a particle, or other regular or irregular shape or convenient combination of shapes, and can be affixed to or relative to a light guide to couple the scintillated light to a photodetector. In some examples, the scintillator element can be shaped as an extension of the light guide and affixed thereto. A photodetector such as a photodiode, an avalanche photodiode, a photomultiplier tube, or the like can be used. The scintillator element is typically located in a Faraday cage, and a bias can be applied such that secondary emissions are directed to the scintillator element.

[0019] An aperture plate is a member that defines apertures through which CPB can be transmitted. The aperture plate can conveniently be metallic, with suitable CPB transmission apertures. In a CPB system, a conductive aperture plate is preferred, and if a non-conductive material is used, such an aperture plate can be provided with a conductive coating. The aperture plate can be provided on a surface of a container, such as a metallic container that forms a Faraday cup (or a portion of a Faraday cup) for collecting incident charged particles transmitted by the associated apertures. Circular apertures are typically used, but other shapes can also be used. The aperture plate typically has a thickness that is less than the effective diameter or other cross-sectional dimension of the associated apertures. For convenience, the apertures used to deliver shaped beams to a workpiece (typically in the lower column) are referred to herein as beam defining apertures (BDAs); for convenience, the apertures located for beam formation based on emissions from a beam source (typically in the upper column) are referred to herein as beam forming apertures (BFAs). In a typical CPB system, the BFAs are used in conjunction with one or more CPB lenses to form CPB that is directed to the BDAs, and then scanned, focused, or otherwise delivered to a workpiece or other target.

[0020] As used herein, a secondary emission element is an object having a surface positioned to receive CPB and generate secondary emissions in response. The secondary emission surface can be provided by a layer or coating that is typically selected to enhance secondary emissions in response to a particular beam type and energy at the secondary emission element. In some cases, a bias can be applied such that CPB is incident on the secondary emission surface at a suitable beam energy to enhance secondary emissions. The secondary emission element can be a plate or other shaped conductor, or be provided as a surface of a container, such as a conductive container that forms a Faraday cage.

[0021] The ET detector or portions thereof are confined in a support member configured to provide or support one or more BDAs for a CPB light column and an alignment hole having a fixed offset relative to the one or more BDAs, as well as a secondary emission surface and a scintillator element. The alignment hole can be used to locate the center or other feature of a focused, unfocused, or partially focused CPB. Based on the determined location and fixed offset, the beam forming portion of the CPB light column, typically the upper column, can be adjusted as appropriate. The support member is generally an elongated member having a length L and an effective cross-sectional area A that defines an effective width w as w = sqrt(A) such that the ratio L / w is at least 2, 5, 7.5, or 10. The support member can have a generally cylindrical or other shape or combination of shapes. In typical examples, the support member includes one or more segments. An inner segment is operable to receive a CPB, and in some examples, when in a state of use, the segment includes or supports one or more BDAs; such as segments are referred to herein as being at an inner end. A segment that is located at or closest to a wall of the vacuum enclosure is referred to as an outer segment or outer end. The outer end generally holds a light guide portion that transmits scintillated light to a detector outside the vacuum enclosure and is coupled to a mechanical vacuum feedthrough operable to move a hole provided by or on a more interior segment relative to a CPB axis.

[0022] As used herein, an image refers to a data array containing measurements of CPB intensity at a plurality of locations. Typically, such an array is two-dimensional, although other types of arrays can be used. Such an array is typically stored in one or more computer readable storage devices, such as memory devices or disk drives. Control systems as used herein can be based on microcontroller circuitry or other logic devices, such as gate arrays.

[0023] As used in this application and in the claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Further, the term “includes” means “comprises.” Additionally, the term “coupled” does not exclude the presence of intermediate elements between coupled items.

[0024] The systems, devices, and methods described herein should not be construed as limiting in any way. Instead, the present disclosure is directed to all novel and nonobvious features and aspects of the various disclosed embodiments, alone and in various combinations and subcombinations with one another. The disclosed systems, methods, and devices are not limited to any specific aspect or feature or combination of aspects and features, nor do the disclosed systems, methods, and devices require that any one or more specific advantages be present or problems be solved.

[0025] Although the operations of some of the disclosed methods are described in a particular, sequential order for convenience, it should be understood that this manner of description encompasses rearrangement, unless a particular ordering is required by specific language set forth below. For example, operations described sequentially can in some cases be rearranged or performed concurrently. Moreover, for the sake of simplicity, the attached figures can not show the various ways in which the disclosed systems, methods and devices can be used or practiced by, with, or in connection with other systems, methods and devices. Additionally, the description sometimes uses terms like “produce” and “provide” to describe the disclosed methods. These terms are high-level abstractions of the actual operations that are performed. The actual operations that correspond to these terms will vary depending on the particular implementation and are readily discernible by one of ordinary skill in the art.

[0026] In some examples, values, programs, or devices are referred to as “lowest,” “best,” “smallest,” etc. It should be understood that such descriptions are intended to indicate that a selection can be made among many used functional alternatives, and that such selection need not be better, smaller, or otherwise preferred than other selections.

[0027] Examples are described with reference to directions indicated as “above,” “below,” “upper,” “lower,” etc. These terms are used for convenience of description, and do not imply any particular spatial orientation. For example, the terms upper column and lower column do not imply a particular spatial orientation of the CPB optics.

[0028] Alignment assembly with light guide

[0029] Reference is made to Figures 1A-1B An alignment device 100 for a CPB system includes a support member having a beam defining aperture (BDA) extension 110 at an inner end, a detector portion 120, a positioning arm 140 at an outer end, and a vacuum feedthrough 150. The positioning arm 140 is coupled to an actuator 152, shown as a 2-axis stage, which allows movement of the positioning arm 140, the detector portion 120, and the BDA extension 110 relative to a charged particle beam (CPB) 125, typically a focused ion beam (FIB). In operation, when located in a vacuum chamber 101, the vacuum feedthrough 150 is operable to allow 2-axis movement of the alignment device 100 relative to the CPB 125.

[0030] In this example, the BDA extension 110 includes a distal portion 114 configured for electrical contact within the vacuum chamber 101 to establish a bias voltage. The BDA extension 110 has a portion 112 in which one or more BDAs are defined. The BDA apertures are typically positioned to transmit incident CPB in use, and can be defined on a BDA aperture plate that includes multiple apertures, such that a degraded BDA can be replaced by another BDA while maintaining vacuum.

[0031] The detector portion 120 includes a detector housing 122 that defines an alignment aperture 124 that forms a Faraday cup and a detector volume 126. As shown, the alignment aperture 124 is positioned to transmit a portion of the incident CPB 125 into the detector volume 126. With actuator 152, the detector housing 122 and the alignment aperture 124 can be translated relative to the CPB beam 125. The portion of the CPB 125 transmitted by the alignment aperture 124 is incident on a secondary emission element formed as a secondary emission surface 128 at which secondary electrons 130 are generated in response to the transmitted beam portion. The alignment aperture 124 is typically a circular aperture, but other shapes can be used. A scintillator element 131 is positioned to receive at least some of the secondary electrons 130 and generate scintillating light 142 that is guided by a light guide 132 to a photomultiplier tube (PMT) 154 or other photodetector, such as an avalanche photodiode or other detector. The light guide 132 can be a glass or plastic optical fiber, a transparent rod of plastic, glass, or other transmissive material, or a cavity defined in a conductive inner sleeve 138 that extends between the scintillator element 131 and a vacuum feedthrough 150. An insulating sleeve 136 couples the detector housing 122 to the positioning arm 140 so that the detector housing 122 and the positioning arm 140 can be set to different voltages.

[0032] In this example, the BDA extensions 110 are typically biased a few kV lower than the potential of the scintillator element 131 (e.g., -1 kV to -5 kV) so that the secondary electrons 130 are directed to the scintillator material 131. In addition, the positioning arm 140 and the conductive inner sleeve 138 are held at ground potential or near ground potential to simplify the construction of the vacuum feedthrough 150. To reduce charging, the scintillator element 131 can be a conductive material, such as a ceramic scintillator material, or a dielectric scintillator material, such as a plastic scintillator provided with an electron-transmissive conductive coating. The secondary emission surface 128 can be an interior surface of the detector volume, such as an aluminum or other metallic surface, or a coating can be applied to enhance secondary emission. It is typically preferred that the direction of incidence of the CPB through the alignment aperture 124 does not correspond to the angle of reflection of the CPB from the scintillator material 131 to reduce debris buildup of the scintillator element 131.

[0033] As Figures 1A-1B shown, the BDAs and the alignment aperture need not be located in a common plane; where portions 112 of one or more BDAs are offset from the alignment aperture 124 along the axis of the CPB column, which is typically parallel to the Z-axis, with a CPB offset measured along the X- and Y-axes of the coordinate system 170.

[0034] Alignment assembly with electron multiplier

[0035] Figure 2is a schematic view of a representative alignment apparatus 200 that includes an alignment aperture 204 defined in an interior portion 206 of a support member. The alignment aperture 204 is positioned to transmit a portion of a CPB 202 to a secondary emission surface 208 disposed on a base 210. An electron multiplier 212, shown as a continuous dynode electron multiplier, is positioned to receive secondary electrons generated at the secondary emission surface 208. In this example, the continuous dynode electron multiplier 212 is shown as a trumpet shape having an entrance aperture 214. Other electron multipliers can be used, such as a discrete dynode electron multiplier or a microchannel plate multiplier. In Figure 2 In the example of FIG. 2, the alignment apparatus 200 is shown as being moved so that the alignment aperture 204 receives the CPB 202; in normal operation, the alignment apparatus is moved so that the CPB 202 is directed to the BDA 240.

[0036] The electron multiplier 212 is coupled to a scintillator element 218 that is positioned to couple scintillated light to a photodetector 220. In this example, the transmitted portion of the CPB 202 propagates along an axis 224 to the secondary emission surface 208. The secondary emission surface 208 is oriented so that specular reflection of the incident CPB beam portion propagates along an axis 226 to avoid coupling into the entrance aperture 214 of the electron multiplier 212. One or more vacuum electrical feedthroughs, such as feedthroughs 230-233 (shown schematically), are provided to couple operating potentials VI, V2, V3 for biasing the electron multiplier 212, suppressing charge buildup on the scintillator element 218, establishing a secondary emission surface voltage, and communicating with the photodetector 220 into the vacuum chamber and coupling detected light signals out of the vacuum chamber. The feedthroughs 230-233 are typically configured to allow mechanical positioning of the BDA 240 and the alignment aperture 204 relative to the CPB 202. In this example, a photodetector is provided at the scintillator element 218, but it is typically more convenient to couple the scintillated light to a light guide that delivers the scintillated light to an external photodetector.

[0037] Focused ion beam (FIB) system

[0038] Reference is made to Figure 3Representative FIB system 300 includes a vacuum enclosure 302 defining a vacuum chamber including an upper chamber 304 and a lower chamber 305, which can be separated by a valve 306, which can be operated with an actuator 326 in response to controller 307. An ion source 308, such as a liquid metal ion source, is positioned to direct an ion beam to an upper optical column including CPB lenses 310, 314 and a beam forming aperture (BFA) 354 defined in a hole plate 312. A lower optical column includes lenses 316, 318 to direct the FIB to a workpiece 320. In some examples, an additional CBP column is provided for electron beam imaging of workpiece 320, such as an electron beam column, but is not shown in Figure 3 Lenses 310, 312, 316, 318 are coupled to respective power supplies 330, 334, 336, 338, which supply current or voltage for lens operation in response to controller 307. Power supply 328 can establish operating conditions for ion beam source 308. In use, CPB lens 314 is typically operated to focus the CPB through beam defining aperture (BDA) 364; during alignment, the CPB can be unfocused or less focused to provide an illumination disk.

[0039] Alignment apparatus 370 includes a support member 372 defining beam limiting aperture 364 and an alignment aperture 366 fixed relative to beam limiting aperture 364 and which transmits a portion of the CPB to a secondary emission surface 365, which is used in normal operation. Scintillator element 368 receives secondary emission to produce scintillating light coupled to a light guide 374 and a photodetector system 375.

[0040] The ion source 308 has an ion emission region 340 that is positioned to direct an ion beam 350 along an axis 352. In operation, the ion emission region 340 moves as shown by ion emission region 341, which can be displaced from the original ion emission region 340 in a direction transverse to the axis 352 or along the axis. The ion emission regions 340, 341 produce respective beams that are directed along axes 360 (in this case, this is the same as the original beam axis 352), 361 from virtual source locations 370, 371, which can depend on the CPB characteristics of the optical column. In some examples, the virtual source locations correspond to the actual locations of the original and displaced emission regions 340, 341, but typically correspond to the emission regions imaged by portions of the upper optical column. In operation, the ion beam is directed through a beam forming aperture 354; as shown, the axis 362 is tilted relative to the axis 360 and is offset from the axis 360 on a plane containing the BDA 364. As shown, the lens 314 can be operated so that the beam formed at or near the plane of the BDA 364 is not focused to provide an illumination disk rather than a focused beam. Alternatively, the CPB can be focused on or near the plane containing the BDA 364. Using the alignment device 370, with the CPB illumination disk or focused CPB, the position of the axis 361 and the associated CPB can be found. In some cases, a pixelated CPB detector can be used and the scan alignment aperture 366 is not needed. The actuator 390 is operated to translate the support member 372, and based on the detected scintillating light, the shape, size, and position of the CPB associated with the ion emission region 341 can be determined using instructions executed by the controller 307, such as a microprocessor or other logic device, and the optical column can be adjusted as appropriate. In some cases, the adjustment is made so that the axis 361 is substantially the same as the axis 360.

[0041] Representative alignment method

[0042] Reference Figure 4AIf desired, the representative method 400 includes isolating the upper chamber of the CPB system with an isolation valve at 402 so that alignment can be performed while the workpiece is changed and a vacuum need not be maintained in the lower chamber. At 404, the CPB can be defocused at or near the BDA plane to form a CPB illumination disk. At 406, the alignment aperture is translated in the defocused CPB and the scintillated light produced in response to secondary emission produced by the transmissive portion of the CPB is measured at 408. At 410, the measured scintillated light can be stored as a beam image and the stored beam image is processed to locate the beam center in one or more directions, typically in a direction transverse to the beam propagation axis. With the beam center located, the CPB offset can be determined at 412 and the source position or the upper column can be adjusted at 414. For example, one or more beam deflectors can be used to establish a propagation axis that is aligned with the upper column and the BDA is centered on this axis, or the beam source can be translated. After adjustment, the alignment process can be repeated for verification. If the upper chamber was isolated at 402, the isolation valve can be opened at 416 and the workpiece is processed at 418. It can be convenient to perform the alignment method using computer executable instructions provided to a logic processor, such as a microprocessor, during workpiece exchange. With this method, automated source alignment can be addressed without venting the vacuum chamber, reducing the loss of processing time in the alignment procedure.

[0043] It is generally preferred to emphasize the measurement of beam current at the edge of the illumination disk. Reference is made to Figure 4B At 452, the alignment aperture is scanned (a coarse / fast scan is generally sufficient) to locate the edge of the illumination disk. At 454, the edge position is selected and at 456, the alignment aperture is scanned at the selected edge position. At 458, the edge position scan is used to find the beam center, for example, using a fitting procedure, such as a non-linear least squares fitting procedure to a circle. In some cases, an ellipse or other shape can be used to represent the illumination disk and used for fitting.

[0044] Figure 4C Such an edge scan is illustrated. In locating the illumination disk 470, edge regions 471-474 are selected and the alignment aperture is scanned at each region to obtain the beam current as a function of alignment aperture position, which can be established using a mechanical stage. Figure 4D The transmitted beam current as a function of position is illustrated for a representative scan based scintillated light detected with a photodetector. In coordinate system 480, edge regions 471, 473 are used for X scans and edge regions 472, 474 are used for Y scans. Other edge regions can be selected and in some cases, edge regions are scanned in a direction other than the X direction or the Y direction.

[0045] In another approach, Bayesian measurements are used. In such methods, a prior probability distribution (“prior”) is selected based on typical bundle characteristics or an arbitrary choice. The bundle is sampled as discussed above, and the sampled measurements are used to update the prior. The sampling / updating process continues until the target accuracy is achieved.

[0046] refer to Figure 5A Method 500 includes guiding the CPB illumination disk to a plane, such as the plane in which the BDA is located, at 502. At 504, scanning the alignment aperture as described above relative to the CPB illumination disk to locate the edge, typically along at least two non-parallel axes. This scanning is associated with a selected number of measurement locations separated by fixed, irregular, periodic, or other intervals. In the central portion of the CPB illumination disk, the illumination level typically does not change significantly, and measuring the CPB illumination disk at the beam edge is preferred for establishing the CPB illumination disk position. At 506, based on scanning the CPB illumination disk with the alignment aperture to locate the illumination disk edge, then scanning the alignment aperture near the illumination disk edge, and at 508, determining the position of the ion beam source. The ion beam source position can be a real ion beam source position or a virtual position established by one or more elements of the CPB beam column. For example, the offset of the center of the CPB illumination disk from the expected CPB beam axis or a previous position can be determined. Lateral offset of the illumination disk can correspond to an offset of the ion beam source, such as... Figure 3 As shown. Based on this offset, at 510, one or more sections of the CPB column can be adjusted. Furthermore, the measurement of the illumination disk also allows for the evaluation of the BFA at 512. For example, a non-circular CPB illumination disk can be associated with degradation of the BFA, and if degradation is detected, the BFA can be replaced.

[0047] exist Figure 5B In another example shown, method 550 includes focusing the CPB at or near the BDA plane at 552 and exposing a pixelated CPB detector to the focused beam at 554. At 556, the CPB source location can be determined based on the beam image provided by the pixelated CPB detector. At 560, the CPB pillar can be adjusted to establish the desired beam location, and at 562, the image data is used to evaluate the BFA. Alignment can also be performed based on the illumination disk using a pixelated detector, and hole scanning may not be required. Furthermore, alignment can also be performed by scanning the alignment hole relative to the focused CPB, and not solely using the illumination disk.

[0048] Alignment assembly with internal photodetector

[0049] refer to Figure 6The alignment apparatus 600 for a CPB system includes a support member shown as a rod that includes an outer portion 602A and an inner portion 602B. The portion 602A holds an optically coupled scintillator material 604 and a photodetector 606. The photodetector is electrically connected by conductors 608 located in a cavity 610 in the portion 602A that carry the optical signal to appropriate amplifiers, typically outside the vacuum into which the alignment apparatus 600 extends. In this example, the scintillator material 604 is shown as elongated so that a portion can act as a light guide to deliver scintillated light to the photodetector 606. The portion 602B defines an aperture 612 into a cavity 614 so that a portion of the CPB 616 can be transmitted to a secondary emission surface 618 defined on a secondary emission element 620. If convenient, the portion 602B can include a mounting portion 630 to which a beam defining aperture plate can be secured. The alignment apparatus 600 can be coupled to a positioning stage so that the alignment aperture can be moved relative to the CPB 616. The portions 602A, 602B can be secured together with adhesive or fasteners such as screws or rivets.

[0050] Representative embodiments

[0051] Example 1 is a charged particle beam alignment apparatus comprising: an alignment aperture plate defining an alignment aperture; a secondary emission element positioned to receive a portion of a CPB transmitted by the alignment aperture and operable to generate a secondary emission in response; a scintillator element positioned to receive at least a portion of the secondary emission and generate scintillated light in response; and a photodetector positioned to receive the scintillated light generated at the scintillator element.

[0052] Example 2 includes the subject matter of Example 1, and further includes an aperture plate secured to a support member and defining at least one beam defining aperture.

[0053] Example 3 includes the subject matter of any of Examples 1 and 2, and further includes a support member having an inner end and an outer end, wherein the alignment aperture plate is secured to the support member and at the inner end of the support member.

[0054] Example 4 includes the subject matter of any of Examples 1-3, and further includes a light guide positioned to receive the scintillated light generated at the scintillator element and direct the scintillated light to the photodetector.

[0055] Example 5 includes the subject matter of any of Examples 1-4, wherein the light guide is an elongated cavity defined in a support member, and the scintillator element is at an entrance end of the light guide.

[0056] Example 6 includes the subject matter of any one of Examples 1-5, and further specifies that the light guide is a dielectric light guide having an entrance end facing the scintillator element.

[0057] Example 7 includes the subject matter of any one of Examples 1-6, and further specifies that the secondary emission element is located on an axis perpendicular to the alignment aperture plate and is tilted away from the scintillator element at an angle between 10 degrees and 80 degrees.

[0058] Example 8 includes the subject matter of any one of Examples 1-7, and further includes a support member that is rod-shaped and extends along an axis, and the support member includes a first electrically conductive section at an inner end and an insulator section coupled to the first electrically conductive section, wherein the first electrically conductive section includes the alignment aperture and the secondary emission element, and the insulator section defines an insulator cavity extending along the axis, wherein the light guide is located in the insulator cavity.

[0059] Example 9 includes the subject matter of any one of Examples 1-8, and further specifies that the support member includes a second electrically conductive section coupled to the insulator section and defining an electrically conductive cavity extending along the axis, wherein the light guide is located in the electrically conductive cavity.

[0060] Example 10 includes the subject matter of any one of Examples 1-9, and further specifies that the second electrically conductive section extends through the insulator cavity and is electrically coupled to the scintillator element.

[0061] Example 11 includes the subject matter of any one of Examples 1-10, and further includes a translation feedthrough coupled to the second electrically conductive section, and the translation feedthrough is operable to change a position of the alignment aperture relative to a CPB axis.

[0062] Example 12 includes the subject matter of any one of Examples 1-11, and further specifies that the scintillator element includes an electrically conductive coating.

[0063] Example 13 includes the subject matter of any one of Examples 1-12, and further includes a controller and an actuator, wherein the controller is coupled to the actuator to move the alignment aperture relative to a CPB axis, and the controller determines an offset of the alignment aperture relative to the CPB axis based on the scintillated light received by the photodetector.

[0064] Example 14 includes the subject matter of any one of Examples 1-13, and further specifies that the controller is coupled to a CPB light column to adjust at least one of a CPB axis and a beam defining aperture based on the determined offset of the alignment aperture.

[0065] Example 15 is a method comprising: aligning an alignment aperture relative to a CPB scan; generating scintillation light at a scintillator member in response to a transmitted portion of the CPB; determining a CPB axis based on the scintillation light.

[0066] Example 16 comprises the subject matter of Example 15, and further comprises capturing at least a portion of the scintillation light in a light guide, wherein determining the CPB axis is based on the scintillation light.

[0067] Example 17 comprises the subject matter of any one of Examples 15-16, and further specifies that the transmitted portion of the CPB is incident to a re-emission member to generate re-emission such that the scintillation light is generated in response to the re-emission, and the method further comprises adjusting at least one of the CPB axis and a beam defining aperture based on the determined CPB axis.

[0068] Example 18 comprises the subject matter of any one of Examples 15-17, and further specifies that the alignment aperture and the beam defining aperture are fixed to a rod-shaped member, the rod-shaped member coupled to an actuator that translates the alignment aperture.

[0069] Example 19 is a CPB apparatus comprising: a vacuum enclosure; a CPB source located in the vacuum enclosure and operable to generate CPB; a CPB optical system positioned along a CPB axis to direct the CPB; a CPB alignment apparatus extending into the vacuum enclosure, wherein the CPB alignment apparatus comprises: a beam limiting aperture plate defining a beam limiting aperture; an alignment aperture plate defining an alignment aperture fixed relative to the beam limiting aperture plate; a re-emission member positioned to receive a portion of the CPB transmitted by the alignment aperture; and a scintillator member positioned to receive re-emission from the re-emission member and generate scintillation light; a mechanical vacuum feedthrough coupled to the CPB alignment apparatus and operable to move at least the alignment aperture relative to a CPB axis; and a controller coupled to the mechanical vacuum feedthrough and a photodetector system, and the controller is operable to direct the mechanical vacuum feedthrough to move the alignment aperture relative to the CPB axis, and determine a CPB position based on a portion of the scintillation light.

[0070] Example 20 includes the subject matter of Example 19, and further specifies that the CPB alignment device includes a rod-shaped support member including: an inner conductive section including the beam-limiting aperture plate, the alignment aperture plate, the secondary emission member, and the scintillator member; an intermediate insulator section defining a cavity in which a light guide is positioned to extend toward the scintillator member; and an outer section coupled to the mechanical vacuum feedthrough, wherein the light guide extends through the vacuum outer shell to the scintillator member.

[0071] In view of the principles of the disclosure, which can be applied to numerous possible embodiments, it should be recognized that the illustrated embodiments are merely preferred embodiments and should not be considered limiting of the scope of the disclosure.

Claims

1. A charged particle beam (CPB) alignment device, the charged particle beam alignment device comprising: Alignment plate, the alignment plate defining alignment holes; A secondary emission element is positioned to receive a portion of the CPB transmitted through the alignment aperture, and the secondary emission element is operable to generate a secondary emission in response. A scintillator element, the scintillator element being positioned to receive at least a portion of the secondary emission and generate scintillating light in response; and A photodetector, positioned to receive the scintillating light generated at the scintillator element. The alignment aperture is movable to receive the charged particle beam, so that the scintillation light is detected by the photodetector, thereby enabling the positioning of the axis of the charged particle beam.

2. The charged particle beam CPB alignment apparatus according to claim 1, further comprising a first perforated plate fixed to a support member and defining at least one beam defining hole.

3. The charged particle beam (CPB) alignment apparatus according to claim 1 further includes a support member having an inner end and an outer end, wherein the alignment plate is fixed to the support member and located at the inner end of the support member.

4. The charged particle beam (CPB) alignment apparatus of claim 3 further includes a light guide positioned to receive the scintillation light generated at the scintillator element and to guide the scintillation light to the photodetector.

5. The charged particle beam (CPB) alignment apparatus of claim 4, wherein the light guide is an elongated cavity defined in the support member, and the scintillator element is located at the entrance end of the light guide.

6. The charged particle beam (CPB) alignment apparatus according to claim 5, wherein the light guide is a dielectric light guide having an inlet end facing the scintillator element.

7. The charged particle beam (CPB) alignment apparatus of claim 1, wherein the secondary emission element is located on an axis perpendicular to the alignment aperture plate and tilted away from the scintillator element at an angle between 10 degrees and 80 degrees.

8. The charged particle beam CPB alignment device according to claim 4, further comprising: A rod-shaped support member extending along an axis, the support member including a first conductive section at an inner end and an insulating section coupled to the first conductive section, wherein the first conductive section includes the alignment hole and the secondary emission element, and the insulating section defines an insulating cavity extending along the axis; as well as An optical guide is located within the cavity of the insulator.

9. The charged particle beam (CPB) alignment apparatus of claim 8, wherein the support member includes a second conductive section coupled to the insulating section and defining a conductive cavity extending along the axis, wherein the photoguide is located in the conductive cavity.

10. The charged particle beam (CPB) alignment apparatus of claim 9, wherein the second conductive segment extends through the insulating cavity and is electrically coupled to the scintillator element.

11. The charged particle beam (CPB) alignment apparatus of claim 10, further comprising a translation feedthrough coupled to the second conductive section, and the translation feedthrough being operable to change the position of the alignment aperture relative to the CPB axis.

12. The charged particle beam (CPB) alignment apparatus of claim 1, wherein the scintillator element comprises a conductive coating.

13. The charged particle beam (CPB) alignment device according to claim 2, further comprising: Controller, and An actuator, wherein a controller is coupled to the actuator to move the alignment aperture relative to the CPB axis, and the controller determines the offset of the alignment aperture relative to the CPB axis based on the flash light received by the photodetector.

14. The charged particle beam (CPB) alignment apparatus of claim 13, wherein the controller is coupled to the CPB beam to adjust at least one of the CPB axis and the beam defining aperture based on a determined offset of the alignment aperture.

15. An alignment method, the method comprising: Relative to the CPB scanning alignment aperture for charged particle beams; In response to a portion of the CPB transmitted through the alignment aperture, a scintillator element is generated, the scintillator element being positioned to receive a secondary emission generated by a secondary emission element, the secondary emission element being positioned to receive a portion of the CPB transmitted through the alignment aperture; The scintillating light generated by the scintillator element is detected using a photodetector configured to receive the scintillating light; The CPB axis is determined based on the detected flickering light; as well as Adjust at least one of the CPB axis and the beam-limiting aperture based on the determined CPB axis, wherein the alignment aperture and the beam-limiting aperture are fixed to a rod-shaped member, the rod-shaped member being coupled to an actuator that translates the alignment aperture.

16. The method of claim 15, further comprising capturing at least a portion of the scintillation light in a light guide that directs the scintillation light to the photodetector.

17. The method of claim 15, further comprising adjusting the beam-limiting aperture based on the determined CPB axis.

18. A charged particle beam (CPB) device, the CPB device comprising: Vacuum enclosure; A CPB source, located within the vacuum enclosure and operable to generate... CPB; The CPB optical system is positioned along the CPB axis to guide the CPB. CPB alignment device, the CPB alignment device extending into the vacuum housing, wherein the CPB alignment device includes: A beam limiting orifice plate, the beam limiting orifice plate defining a beam limiting orifice; Alignment orifice plate, the alignment orifice plate defining an alignment orifice fixed relative to the bundle limiting orifice plate; A secondary transmitting element, positioned to receive a portion of the CPB transmitted through the alignment aperture; and A scintillator element, positioned to receive secondary emission from the secondary emission element and generate scintillating light; a mechanical vacuum feedthrough, coupled to the CPB alignment device and operable to move at least the alignment aperture relative to the CPB axis; and A controller coupled to the mechanical vacuum feedthrough and photodetector system, and operable to guide the mechanical vacuum feedthrough to move the alignment aperture relative to the CPB axis, and to determine the CPB position based on a portion of the scintillation light.

19. The CPB apparatus of claim 18, wherein the CPB alignment apparatus includes a rod-shaped support member, the rod-shaped support member comprising: An internal conductive section, comprising the beam-limiting aperture plate, the alignment aperture plate, the secondary emission element, and the scintillator element; An intermediate insulating section defines a cavity in which a light guide is positioned to extend toward the scintillator element; and An outer section, which is coupled to the mechanical vacuum feedthrough, wherein the light guide extends through the vacuum housing to the scintillator element.

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