Methods for determining virtual source location of liquid metal ion source

Abstract

To provide a charged particle beam alignment apparatus.SOLUTION: Variations in a charged-particle-beam (CPB) source location are determined by scanning an alignment aperture that is fixed with respect to a beam-defining aperture in a CPB, particularly at edges of a defocused CPB illumination disk. The alignment aperture is operable to transmit a CPB portion to a secondary emission surface that produces secondary emission directed to a scintillator element. Scintillation light produced in response thereto is directed out of a vacuum enclosure associated with the CPB via a light guide to an external photodetection system.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

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

[0002] A focused ion beam (FIB) can target a workpiece for evaluation, repair, and fabrication. 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 due to the high beam currents that can be generated. Unfortunately, ion beam emissions from LMISs tend to be generated in emission regions whose positions change over time. Therefore, properly aligned ion beam sources generally become misaligned. While the FIB optical column can be disassembled for realignment, such disassembly can be time-consuming and requires venting the vacuum chamber housing the LMIS and FIB optical column. After realignment and reassembly, the vacuum chamber must be evacuated before use. During this time, the FIB device is unavailable for use. Furthermore, venting can also allow contamination to build up, which must be removed before use. An alternative approach to aligning the beam source in a charged particle beam system is needed. Summary of the Invention

[0003] The charged particle beam alignment device includes an alignment aperture plate defining an alignment aperture and a secondary emission element disposed to receive a portion of the charged particle beam (CPB) transmitted by the alignment aperture and operable to generate a secondary emission in response thereto. The scintillator element is disposed to receive at least a portion of the secondary emission and to generate scintillation light in response thereto. The photodetector receives the scintillation light generated by the scintillator element. By moving the alignment aperture and detecting the scintillation light with the photodetector, the CPB axis can be positioned, thereby compensating for source movement. In some examples, the scintillation light is coupled outside the vacuum enclosure using a light guide to prevent the photodetector from entering the vacuum enclosure.

[0004] The foregoing and other features and advantages of the present disclosure will become more apparent from the following detailed description, which proceeds with reference to the accompanying drawings. [Brief explanation of the drawings]

[0005] [Figure 1A] A representative alignment device is illustrated. [Figure 1B] A representative alignment device is illustrated. [Figure 2] 1 illustrates a portion of another exemplary alignment device. [Figure 3] 1 illustrates a typical focused ion beam (FIB) system including an alignment device. [Figure 4A] A representative alignment method will be illustrated. [Figure 4B] Another representative alignment method will be illustrated. [Figure 4C] 4C illustrates the scanning of the alignment aperture used in the method of FIG. 4B. [Figure 4D] 4D illustrates a graph of beam intensity as a function of scan position relative to the scan area as illustrated in FIG. 4D. [Figure 5A]1 illustrates an alignment method based on detecting the edge of the illumination disc. [Figure 5B] Illustrates an alignment method using a pixelated detector. [Figure 6] 1 illustrates a representative alignment device that includes a photodetector. DETAILED DESCRIPTION OF THE INVENTION

[0006] The disclosed methods and apparatus are directed to measuring the location (either real or virtual) of a liquid metal ion source (LMIS) or other ion source so that the ion beam optics or ion source position provided within the ion beam column can be adjusted to maintain alignment. In some examples, such measurements are performed periodically or on demand. In some cases, the ion source is repositioned to a previously established location, while in other cases, drive levels, such as voltages applied to a charged particle beam (CPB) optical column, are adjusted to compensate for the measured ion source position. Repositioning the ion source to a previously established location allows for ion beam alignment in a simple and straightforward procedure.

[0007] General Terms 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-defining apertures, stigmators, apertures, or other beam-shaping and beam-directing elements. In embodiments, a charged particle beam (CPB) column may be split into two or more sections. It is convenient to describe a 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 may include one or more focusing lenses, stigmators, beam deflectors, and apertures. The lower column may 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 toward a workpiece. In some examples, the lower column focuses the CPB into a spot of a selected size at a selected location on the workpiece. The CPB column is arranged with a vacuum enclosure, which may define upper and lower chambers in which the upper and lower columns are disposed, respectively. The upper and lower chambers can be separated by an isolation valve, for example, so that the upper column can continue to operate during workpiece exchange in the lower chamber, which can reduce upper chamber contamination, pump-down time, and allow for measurement and adjustment of the upper column during workpiece exchange.

[0008] As used herein, an Everhart-Thornley (ET) detector is an electron detector that includes a scintillator material coupled to a light guide, so that scintillation produced by charged particles in the scintillator material (generally referred to herein as scintillation light) is at least partially directed into the light guide for propagation to the photodetector. In the disclosed example, the ET detector may include a plastic or glass light guide, a hollow light guide, a plastic or glass optical fiber, or other light guide. While a typical light guide is depicted as having a circular cross section, the cross section may be elliptical, oval, square, polygonal, or other shape. A circular cross section is convenient for manufacturing, and such light guides are widely available. Scintillator materials such as dielectric scintillators, such as ceramic or 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); bismuth germanium oxide (Bi4Ge3O), generally known as BGO; 12Other inorganic materials such as cadmium tungstate (CdWO), cadmium tungstate (CdWO), silver-doped zinc sulfide (ZnS(Ag)), doped gadolinium oxyorthosilicate (GSO), yttrium aluminum perovskite (YAP), yttrium aluminum garnet (YAG), lutetium oxyorthosilicate (LSO), lutetium aluminum perovskite (LuAP), cerium-activated minerals such as lanthanum bromide (LaBr), and organic crystals such as anthracene can be used. Other types can also be used if desired. The scintillator elements can be provided as cylinders, cubes, sheets, disks, plates, powders, crystalline flakes, particles, other regular or irregular shapes, or combinations of convenient shapes, and can be attached or secured to a light guide to couple scintillation light to a photodetector. In some examples, the scintillator elements can be shaped as an extension of the light guide and attached to the light guide. Photodetectors such as photodiodes, avalanche photodiodes, photomultiplier tubes, or others may be used. The scintillator elements are generally placed within a Faraday cage, and a bias may be applied so that secondary emissions are directed toward the scintillator elements.

[0009] An aperture plate is a member used to define an aperture that transmits to the CPB. The aperture plate is conveniently metallic, with a suitable CPB transmission aperture. In CPB systems, a conductive aperture plate is preferred; if a non-conductive material is used, such an aperture plate may be provided with a conductive coating. An aperture plate may be provided on the surface of a vessel, such as a metallic vessel, that forms a Faraday cup (or a portion of a Faraday cup) for collection of incident charged particles transmitted by the associated aperture. Circular apertures are commonly used, but other shapes can be used as well. Aperture plates generally have a thickness less than the effective diameter or other cross-sectional dimension of the associated aperture. For convenience, apertures that shape the beam for delivery to the workpiece (typically in the lower column) are referred to herein as beam-defining apertures (BDA), and apertures positioned for beam formation based on emission from the beam source (typically in the upper column) are referred to herein as beam-forming apertures (BFA). In a typical CPB system, a BFA is used in conjunction with one or more CPB lenses to form a CPB that is directed to a BDA and then scanned, focused, or otherwise delivered to a workpiece or other target.

[0010] As used herein, a secondary emitting element is an object having a surface configured to receive CPB and generate secondary emission in response thereto. The secondary emitting surface may generally be provided by a layer or coating selected to enhance secondary emission in response to a particular beam type and energy at the secondary emitting element. In some cases, a bias may be applied to enhance secondary emission when CPB is incident on the secondary emitting surface at a suitable beam energy. The secondary emitting element may be a plate or other shaped conductor, or may be provided as the surface of a container, such as a conductive container forming a Faraday cage.

[0011] The ET detector, or portions thereof, are defined within a support member configured to provide or support one or more BDAs for the CPB optical column and alignment apertures having fixed offsets relative to the one or more BDAs along with secondary emission surfaces and scintillator elements. The alignment apertures can be used to locate the center or other features of the focused, unfocused, or partially focused CPB. Based on the determined location and fixed offsets, appropriate adjustments can be made to the beam-forming portion of the CPB optical column (typically the upper column). The support member is generally an elongated member having a length L and an effective cross-sectional area A, which 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 shape or other shapes or combinations of shapes. Typically, the support member includes one or more sections. The inner section is operable to receive a CPB, and in some instances, the section includes or supports one or more BDAs when positioned for use; such sections are referred to herein as being located at the inner end. The section positioned at or closest to the evacuated enclosure wall is referred to as the outer section or outer end. The outer end generally carries a light guide portion that transmits scintillation light to a detector outside the evacuated enclosure and is coupled to a mechanical vacuum feedthrough operable to move an opening provided by or on the more inner section relative to the CPB axis.

[0012] As used herein, an image refers to a data array containing measurements of CPB intensity at multiple 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 a memory device or a disk drive. The control system used herein can be based on a microcontroller circuit or other logic device, such as a gate array.

[0013] As used in this application and the claims, the singular forms "a," "an," and "the" include the plural forms unless the context clearly dictates otherwise. Furthermore, the word "comprises" means "comprises." Furthermore, the word "coupled" does not exclude the presence of intermediate elements between the coupled items.

[0014] 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 non-obvious 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 particular aspect or feature or combination thereof, and the disclosed systems, methods, and devices do not require that any one or more particular advantages be present or problems be solved. Any theory of operation is intended for ease of explanation, but the disclosed systems, methods, and devices are not limited to such theory of operation.

[0015] Although some operations of the disclosed methods are described in a particular sequential order for convenient presentation, it should be understood that this description style encompasses reordering unless a particular ordering is required by specific language set forth below. For example, operations described in sequence may, in some cases, be reordered or performed simultaneously. Moreover, for simplicity, the accompanying figures may not show the various ways in which the disclosed systems, methods, and apparatuses can be used in conjunction with other systems, methods, and apparatuses. Furthermore, the description may use terms such as "generate" and "provide" to describe the disclosed methods. These terms are high-level abstractions of actual operations that take place. The actual operations corresponding to these terms will vary depending on the particular implementation and are readily discernible by those skilled in the art.

[0016] In some instances, values, procedures, or devices are referred to as "lowest," "best," "smallest," etc. It will be understood that such descriptions are intended to indicate that selections can be made from among many functional alternatives used, and that such selections are not necessarily better, lesser, or otherwise preferred than other selections.

[0017] The examples are described with reference to directions indicated as "above," "below," "upper," "lower," etc. These terms are used for convenient description but do not imply a particular spatial orientation. For example, the terms upper column and lower column do not imply a particular spatial orientation of the CPB optics.

[0018] Alignment assembly with light guide 1A-1B, an alignment apparatus 100 for a CPB system includes a support member having a beam-defining aperture (BDA) extension 110 disposed at an inner end, a detector portion 120, a positioning arm 140 disposed at an outer end, and a vacuum feedthrough 150. The positioning arm 140 is coupled to an actuator 152, shown as a two-axis stage, that enables 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). During operation, the vacuum feedthrough 150 is operable to enable two-axis movement of the alignment apparatus 100 relative to the CPB 125 while disposed within a vacuum chamber 101.

[0019] In this example, BDA extension 110 includes a distal portion 114 configured to make electrical contact within vacuum chamber 101 to establish a bias voltage. BDA extension 110 has a portion 112 in which one or more BDAs are defined. The BDA apertures are generally positioned to transmit incident CPB during use and may be defined on a BDA aperture plate containing multiple apertures to allow replacement of a degraded BDA with another BDA while maintaining vacuum.

[0020] The detector portion 120 includes an alignment opening 124 that forms a Faraday cup and a detector housing 122 that defines a detector volume 126. As shown, the alignment opening 124 is positioned to transmit a portion of the incident CPB beam 125 into the detector volume 126. The detector housing 122 and the alignment opening 124 are translatable relative to the CPB beam 125 by an actuator 152. The portion of the CPB 125 transmitted by the alignment opening 124 is incident on a secondary emitting element formed as a secondary emitting surface 128, where secondary electrons 130 are generated in response to the transmitted beam portion. The alignment opening 124 is generally a circular opening, although other shapes can be used. The scintillator element 131 is positioned to receive at least a portion of the secondary electrons 130 and produce scintillation light 142 that is directed by a light guide 132 to a photomultiplier tube (PMT) 154 or other photodetector, such as an avalanche photodiode or other detector. Light guide 132 may be a glass or plastic optical fiber, a transparent rod of plastic, glass, or other transmissive material, or a cavity defined within a conductive inner sleeve 138 that extends between scintillator element 131 and vacuum feedthrough 150. Insulating sleeve 136 couples detector housing 122 to positioning arm 140 so that detector housing 122 and positioning arm 140 can be set to different voltages.

[0021] In this example, the BDA extension 110 is typically biased a few kV below the potential of the scintillator element 131 (e.g., −1 kV to −5 kV), so that secondary electrons 130 are directed toward the scintillator material 131. Additionally, the positioning arm 140 and the conductive inner sleeve 138 are maintained at 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-transparent conductive coating. The secondary emission surface 128 can be an interior surface of the detector volume, such as an aluminum or other metal surface, or a coating can be applied to enhance secondary emission. To reduce debris accumulation on the scintillator element 131, it is generally preferred that the direction of incidence of the CPB through the alignment opening 124 does not correspond to the angle of reflection of the CPB off the scintillator material 131.

[0022] As shown in Figures 1A-1B, the BDAs and alignment openings need not be located in a common plane, and the portion 112 in which one or more BDAs are defined is offset from the alignment opening 124 along the axis of the CPB column, which is generally parallel to the Z axis with the CPB offset measured along the X and Y axes of coordinate system 170.

[0023] Alignment assembly with electron multiplier - Patent Application 20070122997 FIG. 2 is a schematic diagram of an exemplary alignment device 200, including an alignment opening 204 defined within an interior 206 of a support member. The alignment opening 204 is positioned to transmit a portion of a CPB 202 to a secondary emission surface 208 provided on a base 210. An electron multiplier 212, depicted 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 depicted as a horn shape having an entrance opening 214. Other electron multipliers, such as discrete dynode electron multipliers or microchannel plate electron multipliers, can be used. In FIG. 2, the alignment device 200 is shown moved so that the alignment opening 204 receives the CPB 202; in normal operation, the alignment device is moved so that the CPB 202 is directed toward the BDA 240.

[0024] The electron multiplier 212 is coupled to a scintillator element 218 positioned to couple scintillation light to the photodetector 220. In this example, the transmitted portion of the CPB 202 propagates along axis 224 to the secondary emission surface 208. The secondary emission surface 208 is oriented so that the specular reflection of the incident CPB beam portion propagates along axis 226 to avoid coupling to the entrance aperture 214 of the electron multiplier 212. One or more vacuum electrical feedthroughs, such as feedthroughs 230-233 (schematically illustrated), are provided to bias the electron multiplier 212, suppress charge buildup on the scintillator element 218, establish a secondary emission surface voltage, couple operating potentials V1, V2, and V3 to the vacuum chamber for communication with the photodetector 220, and couple detected light signals from the vacuum chamber. The feedthroughs 230-233 are generally configured to enable mechanical positioning of the BDA 240 and alignment aperture 204 relative to the CPB 202. In this example, a photodetector is provided in the scintillator element 218, although it is typically more convenient to couple the scintillation light into a light guide that delivers the scintillation light to an external photodetector.

[0025] Focused Ion Beam (FIB) System 3, a typical FIB system 300 includes a vacuum enclosure 302 defining a vacuum chamber with an upper chamber 304 and a lower chamber 305, which can be separated by a valve 306 operable with an actuator 326 in response to a controller 307. An ion source 308, such as a liquid metal ion source, is positioned to direct an ion beam into an upper optical column including CPB lenses 310 and 314 and a beam-forming aperture (BFA) 354 defined in an aperture plate 312. The lower optical column includes lenses 316 and 318 that direct the FIB to a workpiece 320. In some examples, an additional CPB column, such as an electron beam column, is provided for e-beam imaging of the workpiece 320, but is not shown in FIG. 3. The lenses 310, 312, 316, and 318 are coupled to respective power supplies 330, 334, 336, and 338 that provide current or voltage for lens operation in response to the controller 307. The power supply 328 can establish the operating conditions of the ion beam source 308. In use, the CPB lens 314 generally operates to focus the CPB through the beam-defining aperture (BDA) 364; during alignment, the CPB may be unfocused or poorly focused to provide an illumination disk.

[0026] Alignment device 370 includes a support member 372 that defines a beam-limiting aperture 364 used in normal operation and an alignment aperture 366 that is fixed relative to beam-limiting aperture 364 and transmits a portion of the CPB to secondary emission surface 365. Secondary emissions received by scintillator element 368 produce scintillation light that is coupled into light guide 374 and photodetector system 375.

[0027] The ion source 308 has an ion emission region 340 positioned to direct an ion beam 350 along an axis 352. During operation, the ion emission region 340 moves, shown as ion emission region 341, which can be displaced from the original ion emission region 340 either transversely or along the axis 352. The ion emission regions 340, 341 generate respective beams directed along axes 360 (which in this case is the same as the original beam axis 352) and 361, respectively, from virtual source locations 370, 371, which may 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 generally correspond to the emission region imaged by a portion of the upper optical column. During operation, the ion beam is directed through a beam-forming aperture 354, and as shown, axis 362 is tilted relative to axis 360 and displaced from axis 360 in a plane containing the BDA 364. As shown, lens 314 can be operated so that the beam formed at or near the plane of BDA 364 is not focused, providing an illumination disk instead of a focused beam. Alternatively, the CPB can be focused at or near a plane containing BDA 364. Using alignment device 370, axis 361 and the associated CPB position can be found using either a CPB illumination disk or a focused CPB. In some cases, a pixelated CPB detector can be used, and scanning of alignment aperture 366 is not required. Actuator 390 operates to translate support member 372, and based on the detected scintillation light, the shape, size, and position of the CPB relative to ion emission region 341 can be determined using instructions executed by controller 307, such as a microprocessor or other logic device, and the optical column can be suitably adjusted. In some cases, adjustments are made so that axis 361 is substantially the same as axis 360.

[0028] Typical alignment methods Referring to FIG. 4A , an exemplary method 400 includes isolating the upper chamber of the CPB system with an isolation valve at 402, if desired, so that alignment can occur while workpieces are being changed, eliminating the need to maintain a vacuum 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 scintillation light generated in response to secondary emissions arising from the transmitted portion of the CPB is measured at 408. The measured scintillation light can be stored as a beam image, which is processed at 410 to locate the beam center in one or more directions, typically transverse to the beam propagation axis. Once the beam center is located, the CPB offset can be determined at 412, and the source location or upper column can be adjusted at 414. For example, one or more beam deflectors can be used to establish a propagation axis aligned with the upper column, and the BDA can be centered on this axis, or the beam source can be translated. After adjustment, the alignment process can be repeated for verification. When the upper chamber is isolated at 402, an isolation valve can be opened at 416, and the workpiece can be processed at 418. During workpiece exchange, it can be convenient to implement the alignment method using computer-executable instructions provided to a logic processor, such as a microprocessor. In this manner, automatic source alignment can be accommodated without venting the vacuum chamber, reducing processing time spent on the alignment procedure.

[0029] Generally, it is preferable to emphasize measuring the beam current at the edge of the illumination disk. Referring to FIG. 4B, at 452, an alignment aperture is scanned (a coarse / fast scan is generally sufficient) to locate the edge of the illumination disk. At 454, an edge location is selected, and at 456, the alignment aperture is scanned at the selected edge location. At 458, the edge location scan is used to find the beam center relative to the circle, for example, by using a fitting procedure such as a nonlinear least-squares fitting procedure. In some cases, an ellipse or other shape can be used to represent the illumination disk and used in the fitting.

[0030] FIG. 4C illustrates such an edge scan. Once illumination disk 470 is positioned, edge regions 471-474 are selected and the alignment aperture is scanned across each to obtain beam current as a function of alignment aperture position, which can be established using a mechanical stage. FIG. 4D illustrates transmitted beam current as a function of position for a representative scan based on scintillation light detected at a photodetector. In coordinate system 480, edge regions 471 and 473 are used in the X scan, and edge regions 472 and 474 are used in the Y scan. Other edge regions can be selected, and in some cases, the edge regions are scanned in directions other than the X or Y directions.

[0031] Another approach uses Bayesian measurements. In such an approach, a prior probability distribution ("prior") is chosen based on typical beam characteristics or an arbitrary choice. The beam is sampled as discussed above, and the sample measurements are used to update the prior distribution. The sampling / updating process continues until the target accuracy is achieved.

[0032] Referring to FIG. 5A , method 500 includes orienting a CPB illumination disk at a plane, such as the plane on which the BDA is disposed, at 502. At 504, the alignment aperture described above is scanned relative to the CPB illumination disk to typically locate the edge along at least two non-parallel axes. This scan 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 vary substantially, and measurements of the CPB illumination disk at the beam edge are preferred to establish the location of the CPB illumination disk. To locate the illumination disk edge based on scanning the CPB illumination disk with the alignment aperture, the alignment aperture is then scanned around the illumination disk edge at 506, and the location of the ion beam source is determined at 508. The ion beam source location may be the location of a real ion beam source or a virtual location established by one or more elements of a CPB optical column. For example, the offset of the center of the CPB illumination disk from the intended CPB column axis or previous location can be determined. The lateral offset of the illumination disk can correspond to the offset of the ion beam source, as shown in FIG. 3. Based on this offset, one or more portions of the CPB column can be adjusted, at 510. In addition, measurement of the illumination disk also allows for 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.

[0033] In another example shown in FIG. 5B , a method 550 includes focusing a CPB at or near a BDA plane at 552 and exposing a pixelated CPB detector to the focused beam at 554. The location of the CPB source can be determined at 556 based on a beam image provided by the pixelated CPB detector. The CPB column can be adjusted at 560 to establish the intended beam position, and the image data is used to evaluate the BFA at 562. Using a pixelated detector, alignment can similarly be performed based on an illumination disk; aperture scanning may not be required with a pixelated detector. Additionally, alignment can also be performed by scanning an alignment aperture relative to the focused CPB, rather than just the illumination disk.

[0034] Alignment assembly with internal photodetector Referring to FIG. 6 , an alignment device 600 for a CPB system includes a support member shown as a rod including an outer portion 602A and an inner portion 602B. Portion 602A holds an optically coupled scintillator material 604 and a photodetector 606. The photodetector is electrically connected via a conductor 608 disposed within a cavity 610 within portion 602A, which transmits an optical signal to a suitable amplifier, typically outside the vacuum through which alignment device 600 extends. In this example, scintillator material 604 is shown as elongated so that a portion can act as a light guide to deliver scintillation light to photodetector 606. Portion 602B defines an opening 612 into cavity 614 so that a portion of CPB 616 can transmit to a secondary emitting surface 618 defined on secondary emitting element 620. Optionally, portion 602B can include a mounting portion 630 to which a beam-defining aperture plate can be attached. The alignment device 600 can be coupled to a positioning stage such that the alignment opening is movable relative to the CPB 616. The portions 602A, 602B can be attached together with adhesive or fasteners such as screws or rivets.

[0035] Representative Examples Example 1 is a charged particle beam alignment device that includes an alignment aperture plate defining an alignment aperture, a secondary emission element arranged to receive a portion of the CPB transmitted by the alignment aperture and operable to generate a secondary emission in response, a scintillator element arranged to receive at least a portion of the secondary emission and generate scintillation light in response, and a photodetector arranged to receive the scintillation light generated by the scintillator element.

[0036] Example 2 includes the subject matter of example 1, further including an aperture plate secured to the support member and defining at least one beam-defining aperture.

[0037] Example 3 includes the subject matter of any of Examples 1-2, further including a support member having an inner end and an outer end, wherein the alignment aperture plate is attached to the support member and positioned at the inner end of the support member.

[0038] Example 4 includes the subject matter of any of Examples 1-3, further including a light guide positioned to receive scintillation light generated in the scintillator element and direct the scintillation light to the photodetector.

[0039] Example 5 includes the subject matter of any of Examples 1-4, wherein the light guide is an elongated cavity defined within the support member, and the scintillator element is disposed at an entrance end of the light guide.

[0040] Example 6 includes the subject matter of any of Examples 1-5, further specifying that the light guide is a dielectric light guide having an entrance end facing the scintillator element.

[0041] Example 7 includes the subject matter of any of Examples 1-6, further providing that the secondary emitting elements are disposed on an axis perpendicular to the alignment aperture plate and tilted at an angle between 10 degrees and 80 degrees away from the scintillator elements.

[0042] Example 8 includes the subject matter of any of Examples 1-7, further including: the support member is rod-shaped and extends along an axis, comprising a first conductive section disposed at an inner end and an insulator section coupled to the first conductive section, the first conductive section including an alignment opening and a secondary emitting element, the insulator section defining an insulator cavity extending along the axis, and the light guide disposed within the insulator cavity.

[0043] Example 9 includes the subject matter of any of Examples 1-8, further specifying that the support member includes a second conductive section coupled to the insulator section and defining a conductive cavity extending along the axis, and the light guide is disposed within the conductive cavity.

[0044] Example 10 includes the subject matter of any of Examples 1-9, further providing that the second conductive section extends through the insulator cavity and is electrically coupled to the scintillator element.

[0045] Example 11 includes the subject matter of any of Examples 1-10, further including a translation feedthrough coupled to the second conductive section and operable to vary a position of the alignment opening relative to the CPB axis.

[0046] Example 12 includes the subject matter of any of Examples 1-11, further providing that the scintillator element includes a conductive coating.

[0047] Example 13 includes the subject matter of any of Examples 1-12, further including a controller and an actuator, wherein the controller is coupled to the actuator to move the alignment opening relative to the CPB axis and determine an offset of the alignment opening relative to the CPB axis based on scintillation light received by the photodetector.

[0048] Example 14 includes the subject matter of any of Examples 1-13, further specifying that a controller is coupled to the CPB optical column to adjust at least one of the CPB axis and the beam-defining aperture based on the determined offset of the alignment aperture.

[0049] Example 15 includes scanning an alignment opening relative to the CPB, generating scintillation light in a scintillator member in response to the transmitted portion of the CPB, and determining a CPB axis based on the scintillation light.

[0050] Example 16 includes the subject matter of example 15, further including capturing at least a portion of the scintillation light in a light guide, and wherein determining the CPB axis is based on the scintillation light.

[0051] Example 17 includes the subject matter of any of Examples 15-16, further specifying that the transmitted portion of the CPB is incident on a secondary emitting member to generate a secondary emission, such that scintillation light is generated in response to the secondary emission; and further including adjusting at least one of the CPB axis and the beam-defining aperture based on the determined CPB axis.

[0052] Example 18 includes the subject matter of any of Examples 15-17, further specifying that the alignment aperture and the beam-defining aperture are attached to a rod-shaped member coupled to an actuator that translates the alignment aperture.

[0053] Example 19 is a CPB apparatus including: a vacuum enclosure; a CPB source disposed within the vacuum enclosure and operable to generate CPB; a CPB optical system disposed to direct the CPB along a CPB axis; a CPB alignment apparatus extending into the vacuum enclosure, the CPB alignment apparatus including 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 secondary emission member disposed to receive a portion of the CPB transmitted by the alignment aperture; a scintillator member disposed to receive secondary emissions from the secondary emission member and produce scintillation light; a mechanical vacuum feedthrough coupled to the CPB alignment apparatus and operable to move at least the alignment aperture relative to the CPB axis; and a controller coupled to the mechanical vacuum feedthrough and to a photodetector system and operable to orient the mechanical vacuum feedthrough to move the alignment aperture relative to the CPB axis and to determine a CPB position based on a portion of the scintillation light.

[0054] Example 20 includes the subject matter described in Example 19, further specifying that the CPB alignment device includes a rod-shaped support member having an inner section conductive section including a beam-limiting aperture plate, an alignment aperture plate, a secondary emission member, and a scintillator member, an intermediate insulator section defining a cavity in which a light guide is disposed to extend toward the scintillator member, and an outer section coupled to a mechanical vacuum feedthrough, in which the light guide extends through the vacuum enclosure to the scintillator member.

[0055] In view of the numerous possible embodiments to which the principles of the present disclosure may be applied, it should be recognized that the illustrated embodiments are preferred examples only and should not be construed as limiting the scope of the present disclosure.

Claims

1. A charged particle beam alignment device, A positioning opening plate that defines the positioning opening, A secondary emission element is positioned to receive a portion of the charged particle beam (CPB) transmitted through the aforementioned alignment opening, and is operable to generate secondary emission accordingly. A scintillator element is arranged to receive at least a portion of the secondary emission and, in response, generate scintillation light, The system comprises a photodetector arranged to receive the scintillation light generated in the scintillator element, A charged particle beam alignment device in which the alignment aperture is movable to receive the CPB so that the scintillation light can be detected by the photodetector and the axis of the CPB can be positioned.

2. The charged particle beam alignment device according to claim 1, further comprising an aperture plate fixed to a support member and defining at least one beam definition aperture.

3. The charged particle beam alignment device according to claim 1, further comprising a support member having an inner end and an outer end, wherein the alignment opening plate is attached to the support member and positioned at the inner end of the support member.

4. The charged particle beam alignment device according to claim 1, further comprising an optical guide that receives the scintillation light generated in the scintillator element and is arranged to direct the scintillation light toward the photodetector.

5. The charged particle beam alignment device according to claim 4, wherein the optical guide is an elongated cavity defined within a support member, and the scintillator element is positioned at the entrance end of the optical guide.

6. The charged particle beam alignment apparatus according to claim 5, wherein the optical guide is a dielectric optical guide having an entrance end facing the scintillator element.

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

8. A rod-shaped support member further comprising a first conductive section extending along an axis and positioned at an internal end, and an insulating section coupled to the first conductive section, The first conductive section includes the alignment opening and the secondary emission element, The insulating section defines an insulating cavity extending along the axis, The charged particle beam alignment device according to claim 1, further comprising the provision that an optical guide is disposed within the insulating cavity.

9. The charged particle beam alignment device according to 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, and the optical guide is disposed within the conductive cavity.

10. The charged particle beam alignment apparatus according to claim 9, wherein the second conductive section extends through the insulating cavity and is electrically coupled to the scintillator element.

11. The charged particle beam alignment apparatus according to claim 10, further comprising a translational feedthrough coupled to the second conductive section and operable to change the position of the alignment opening with respect to the CPB axis.

12. The charged particle beam alignment apparatus according to claim 1, wherein the scintillator element includes a conductive coating.

13. Controller and The charged particle beam alignment apparatus according to claim 1, further comprising: an actuator, the controller being coupled to the actuator to move the alignment opening relative to the CPB axis, and determining the offset of the alignment opening relative to the CPB axis based on the scintillation light received by the photodetector.

14. The charged particle beam alignment apparatus according to claim 13, wherein the controller is coupled to the CPB optical column to adjust at least one of the CPB axis and the beam delimiting aperture based on the determined offset of the alignment aperture.

15. It is a method, Scanning the alignment aperture relative to the charged particle beam (CPB), The scintillator member generates scintillation light in response to the portion of the CPB transmitted through the alignment opening, wherein the scintillator member is arranged to receive secondary emission generated by a secondary emission element arranged to receive a portion of the CPB transmitted through the alignment opening. The scintillation light generated by the scintillator member is detected by a photodetector arranged to receive the scintillation light, Based on the aforementioned scintillation light, the CPB axis is determined, A method comprising adjusting at least one of the CPB axis and the beam delimiting aperture based on the determined CPB axis.

16. The method of claim 15, further comprising capturing at least a portion of the scintillation light in an optical guide that directs the scintillation light to the photodetector, wherein determining the CPB axis is based on the scintillation light.

17. The method according to claim 15, further comprising adjusting the beam delimitation aperture based on the determined CPB axis.

18. The method according to claim 15, wherein the alignment opening and the beam defining opening are attached to a rod-shaped member coupled to an actuator that translates the alignment opening.

19. A charged particle beam (CPB) apparatus, Vacuum enclosure and A CPB source, disposed within the vacuum enclosure and operable to generate a charged particle beam (CPB), A CPB optical system arranged to orient the CPB along the CPB axis, A CPB alignment device extending into the vacuum housing, A beam limiting aperture plate that defines the beam limiting aperture, A positioning aperture plate that defines a positioning aperture fixed to the beam limiting aperture plate, A secondary discharge member is positioned to receive the portion of the CPB that has been transmitted through the alignment opening, The CPB alignment device includes a scintillator member arranged to receive secondary emission from the secondary emission member and generate scintillation light, A mechanical vacuum feedthrough coupled to the CPB alignment device and operable to move at least the alignment opening relative to the CPB axis, A CPB apparatus comprising a controller coupled to the mechanical vacuum feedthrough and photodetector system, which is operable to direct the mechanical vacuum feedthrough so as to move the alignment opening relative to the CPB axis, and to determine the CPB position based on a portion of the scintillation light.

20. The CPB alignment device includes a rod-shaped support member, and the rod-shaped support member is The inner conductive section includes the beam limiting aperture plate, the alignment aperture plate, the secondary emission member, and the scintillator member, An intermediate insulating section defining a cavity, wherein the optical guide is positioned to extend toward the scintillator member, The CPB apparatus according to claim 19, comprising an outer section coupled to the mechanical vacuum feedthrough, wherein the optical guide extends through the vacuum housing to the scintillator member.

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