Beam splitter integrated with Schottky thermal field emission (TFE) source, method for integrating a Schottky thermal field emission (TFE) source with a beam splitter, and method for forming multiple beams

Abstract

PURPOSE: To provide a system for preventing long-distance movement of a pre-split high current beam.CONSTITUTION: A beam splitter 314 integrated with a Schottky thermal field emitter (TFE) source comprises: a Schottky TFE 304 having an extractor faceplate 308; a standoff 309 integrated with the extractor faceplate; and a microhole array plate 315 which is integrated with the standoff, disposed opposite the extractor faceplate and has a plurality of microholes.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] Embodiments of the present invention relate to a beam splitter integrated with a Schottky Thermal Field Emission (TFE) source, a method for integrating a Schottky Thermal Field Emission (TFE) source with a beam splitter, and a method for forming multiple beams. In general, the present invention relates to a Schottky Thermal Field Emitter (TFE) extractor in which the beam splitter and a micro-hole array plate are integrated by a standoff, which supports the beam splitter's micro-hole array plate above and adjacent to the extractor. [Background technology]

[0002] A scanning electron microscope (SEM) requires a field emission gun (FEG) to generate the electron beam that is used to bombard a target material. The FEG may include a Schottky TFE emitter as the electron beam source.

[0003] Early SEMs only had a single electron beam, and each beam could only scan a small target area, so raster scanning a single target took many hours / days.

[0004] Attempts have been made to use multiple beams or beamlets. Previous efforts have included using a stand-alone beam splitter as an array of holes in a solid foil and placing this stand-alone beam splitter at a location away from the source of thermal field emission, such as inside the FEG or outside the column.

[0005] These design limitations include, but are not limited to: (1) The large beam current before splitting must travel a long distance before reaching the splitter, which creates undesirable extensive stochastic space charge effects, leading to a broader electron energy spread and trajectory displacements, resulting in beamlet blurring and defocusing. (2) The strongly diverging beam emitted by the Schottky TFE has only a small number of electrons passing through each individual hole in the remote standalone beam splitter, so the total current in each split beam (beamlet) is very small.

[0006] The Schottky TFE source consists of a single crystal tungsten wire with a very sharp tip with a zirconium reservoir around the periphery of the tungsten wire. The tip is attached to a hairpin filament, which is used to maintain the tip at a temperature of 1750K to 1850K. This assembly is mounted on a ceramic base and two electrodes are added.

[0007] The first electrode is a suppressor with an opening surrounding the tungsten wire. The second electrode is an extractor with an opening just above the tip of the wire. The tip protrudes through the suppressor opening and faces the extractor, which may be considered the anode of a conventional triode gun consisting of a Schottky tip, suppressor, and extractor. Electrons are emitted from the tip due to both thermal excitation and an electric field at the tip. The radius of the tip typically ranges from 0.3 microns to 1.0 microns. The center hole of the extractor is typically 0.5 microns from the tip.

[0008] When an electron beam is released from a Schottky TFE emitter, the beam broadens due to the lensing effect of the extractor, the thermal velocity of the electrons, and the Boersch effect, which refers to the stochastic Coulomb interaction between electrons, which increases the energy spread of the electrons, causing increased chromatic aberration and trajectory deviation.

[0009] The FEG holds the Schottky TFE emitter and has further electrodes to shape and align the beam. The function of these electrodes is to focus the beam into the FEG exit aperture, also known as the differential pumping aperture. The inside of the FEG is under vacuum and typically contains 4×10 -9With pressures below Torr.

[0010] However, a single TFE can only deliver a single narrow beam to the target. Conventional solutions involve splitting the electron beam with a beam splitter located at some point after the cathode electrode and before the exit aperture of the FEG.

[0011] Attempts have been made to include beam splitters within the FEG. Figure 1 is a schematic diagram showing a Schottky TFE emitter including a beam splitter in a comparative example of one embodiment. Figure 1 also shows a beam splitter 114 located inside the FEG 102 but at a distance from the Schottky TFE emitter 104, the suppressor 106, and the faceplate of the extractor 108. The FEG 102 holds the Schottky TFE emitter 104 in a vacuum. The vacuum on the FEG side is 10 -9Torr. The tip 105 is positioned behind the extractor 108. When the tip 105 emits electrons, the electrons are attracted towards the extractor 108 by the potential at the extractor 108. In a non-limiting example, the extractor voltage can be on the order of 2 kV to 7 kV. The top surface of the extractor 108 (in FIG. 1, the bottom surface of the extractor 108) is a TFE faceplate. The electron beam 116 is shaped by the extractor 108 and the electrodes 110, 112, and the electron beam is focused on the beam splitter 114. The split beams 118 (beamlets) exit the beam splitter 114 and are focused by the underlying optics onto a target (not shown in FIG. 1). At the target, instead of a single beam, the split beams 118 (beamlets) can simultaneously scan a larger area of ​​the target than a single beam. However, with this approach, the current density of the beam passing through the beam splitter 114 is low because the energy spread and trajectory displacement of the raw electron beam 116 is high due to space charge effects over the long distance the raw beam travels from the extractor 108 to the beam splitter 114. Furthermore, maintaining a high vacuum is difficult, which makes the multi-electrode device expensive to manufacture.

[0012] Another conventional solution is to place the beam splitter outside the FEG, somewhere inside the lens barrel. FIG. 2 is a schematic diagram showing a beam splitter supported above the extractor faceplate of a Schottky TFE emitter in a comparative example of one embodiment. FIG. 2 also shows a schematic diagram of a FEG 202 including a Schottky TFE emitter 204 with a tip 205, an aperture plate 206, and an extractor 208. The electron beam 216 diverges until it reaches a collimator lens 220. The collimated beam then passes through a beam splitter 214 to form split beams 218. A condenser lens 222, a blanker aperture 224, a beam stopper 226, and a projection lens 230 focus the split beams 218 (beamlets) onto a target 234. The beam stopper 226 removes excess divergence of each split beam 218, as these diverging beams 228 can cause noise at the target. However, the split beam 218 at the target in the conventional solution of FIG. 2 has a lower current due to the larger diameter of the beam before splitting at the beam splitter 214 . Summary of the Invention [Problem to be solved by the invention]

[0013] Each of the aforementioned structures suffers from one or more drawbacks that prevent their adoption. Thus, in the following, one objective of the embodiments is to provide a beam splitter integrated with a Schottky TFE emitter that splits the electron beam before the beam diverges widely, thereby keeping the current of each split beam high and reducing space charge effects by splitting the beam very close to the beam's origination point (the Schottky tip). Thus, in the following, the embodiments provide a method and system for preventing long distance travel of the high current beam before splitting. [Means for solving the problem]

[0014] In accordance with one embodiment of the present invention, a beam splitter integrated with a Schottky thermal field emission (TFE) source comprises: a Schottky TFE emitter with an extractor faceplate; a standoff integral with said extractor faceplate; a micro-hole array plate, integral with the standoffs and positioned opposite the extractor faceplate, the micro-hole array plate having a plurality of micro-holes; The present invention is characterized by comprising:

[0015] It is also preferred that the extractor faceplate, the standoffs, and the micro-hole array plate are manufactured from the same material.

[0016] Also preferred are the same materials mentioned above, titanium-zirconium-molybdenum, titanium, or stainless steel.

[0017] Alternatively, the same material is preferably a machinable conductive ceramic material.

[0018] Preferably, the machinable, conductive ceramic material is alumina.

[0019] Alternatively, it is preferred that the extractor faceplate, the standoffs and the micro-hole array plate are manufactured from the same or different materials.

[0020] It is also preferred that the extractor faceplate is fabricated from stainless steel, the standoffs are fabricated from a resistive material, and the micro-hole array plate is fabricated from a machinable ceramic material.

[0021] Alternatively, it is preferred that the extractor faceplate is fabricated from stainless steel and the standoffs and the micro-hole array plate are fabricated from a machinable, conductive ceramic material.

[0022] Preferably, the machinable ceramic material is alumina.

[0023] Also, a first end of a standoff is integral with the extractor faceplate; Preferably, the mounting feature is disposed on a second end of the standoff and configured to connect the standoff to the micro-hole array plate.

[0024] Also, it is preferable that the standoffs separate the micro-hole array plate from the extractor face plate by 0.5 mm to 2 mm.

[0025] It is also preferable that the microhole array of the microhole array plate is a 3×3 array, a 4×5 array, or a 5×5 array.

[0026] It is also preferable that each of the microholes in the microhole array plate has the same diameter, and that the diameter is from 10 microns to 120 microns.

[0027] It is also preferred that the microholes increase in size from the centre of the beam splitter towards the periphery of the beam splitter.

[0028] A method for integrating a Schottky thermal field emission (TFE) source and a beam splitter according to one embodiment of the present invention includes the steps of: 1. A beam splitter integration method for integrating a beam splitter with an extractor faceplate of a Schottky TFE emitter, comprising: integrating a first end of a standoff into the extractor faceplate; forming microholes in a substrate to form a microhole array plate; attaching the micro hole array plate to a second end of the standoff; Equipped with the second end is opposite the first end; The standoffs support the micro-hole array plate at a distance of 0.5 mm to 2 mm above the extractor faceplate. It is characterized by:

[0029] and, welding the first end of the standoff to the extractor faceplate; or or, integrally mounting the first end of the standoff to the extractor faceplate by brazing the standoff to the extractor faceplate; integrally integrating the first end of the standoff by machining a groove therein, inserting the extractor faceplate into the groove, and welding the extractor faceplate to the standoff; It is preferable that the sensor further comprises:

[0030] Preferably, the method further comprises attaching the micro hole array plate to the standoffs by welding, friction stir welding, soldering, clamping, or bonding with a hot adhesive.

[0031] In addition, in the step of forming a microhole array plate, a plurality of microholes are formed in the substrate by microdrilling, Preferably, the diameter of the micro-holes increases from the centre of the micro-hole array plate towards the periphery of the micro-hole array plate.

[0032] In addition, in the step of forming the microhole array plate, the microholes in the microhole array plate are formed by micromachining; Suitably, the micromachining comprises microdrilling or chemical etching.

[0033] A multi-beam forming method according to one aspect of the present invention includes: 1. A multi-beam forming method for forming a plurality of electron beams, comprising: powering a Schottky thermal field emission (TFE) emitter to generate an electron beam at an extractor aperture; applying a voltage to the extractor contacts; splitting the electron beam into multiple electron beams by passing the electron beam through a micro-hole array plate comprising a plurality of micro-holes, the micro-hole array plate being supported 0.5 mm to 2 mm above an extractor faceplate by standoffs integral with the extractor faceplate; The present invention is characterized by comprising: Effect of the Invention

[0034] According to one aspect of the invention, the long travel of the high current beam before splitting is prevented. Thus, a beam splitter integrated with a Schottky TFE emitter can split the electron beam before the beam becomes widely divergent. This keeps the current of each split beam high and reduces space charge effects by splitting the beam very close to the point of beam generation (the Schottky tip). [Brief description of the drawings]

[0035] [Figure 1] FIG. 1 is a schematic diagram illustrating a Schottky TFE emitter including a beam splitter in a comparative example of one embodiment. [Diagram 2] FIG. 13 is a schematic diagram showing a beam splitter supported above the extractor faceplate of a Schottky TFE emitter in a comparative example of one embodiment. [Diagram 3] FIG. 1 is a schematic diagram showing a beam splitter integrated with the faceplate of the extractor of a Schottky TFE emitter in one embodiment. [Figure 4A] FIG. 1 is a schematic diagram illustrating an array of micro-holes in a rectangular beam splitter in one embodiment. [Figure 4B]FIG. 13 is a schematic diagram of a circular beam splitter with an array of equally spaced microholes in a variation of an embodiment. [Figure 4C] FIG. 1 is a schematic diagram of a circular beamsplitter with a rectangular 5×5 array of microholes with increasing diameter from the center to the periphery of the beamsplitter in one embodiment. [Diagram 5] FIG. 1 is a schematic diagram showing a Schottky TFE emitter with integrated beam splitter and extractor in one embodiment. [Figure 6A] FIG. 6 is a schematic diagram showing the integration of a Schottky TFE emitter with standoffs 609 in one embodiment. [Figure 6B] FIG. 13 is a schematic diagram illustrating a mounting feature for integrating a beamsplitter array with standoffs in one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] Below, embodiments are described that integrate a Schottky thermal field emission (TFE) with a beam splitter having an array of micro-holes, where the beam splitter is supported above and adjacent to the extractor faceplate of the Schottky TFE emitter by standoffs that are integrated with the extractor faceplate.

[0037] A first embodiment describes a beam splitter integrated with a thermal field emission (TFE) source, the beam splitter comprising a Schottky TFE emitter having an extractor faceplate, a standoff integrated with the extractor faceplate, and a micro-hole array plate integrated with the standoff and positioned opposite the extractor faceplate, with a plurality of micro-holes formed in the micro-hole array plate.

[0038] A second embodiment describes a method for integrating a beam splitter with an extractor faceplate of a Schottky TFE emitter, comprising the steps of integrating a first end of a standoff with the extractor faceplate, forming holes in a micro-hole array plate, and attaching the micro-hole array plate to a second end of the standoff, where the second end is opposite the first end, and where the standoff supports the micro-hole array plate above the extractor faceplate at a distance in the range of 0.5 mm to 2 mm.

[0039] A third embodiment describes a method for forming multiple electron beams, the method including: powering a Schottky TFE emitter to generate an electron beam at an extractor aperture; providing a voltage to an extractor contact; and splitting the electron beam into multiple electron beams by passing the electron beam through a micro-hole array plate comprising a plurality of micro-holes, the micro-hole array plate being supported 0.5 mm to 2 mm above the extractor aperture by a standoff integrated with the extractor aperture.

[0040] The foregoing general description of the exemplary embodiments and the following detailed description are merely exemplary teaching aspects of the present disclosure and are not restrictive.

[0041] A more complete understanding of the present disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, in which:

[0042] Reference is now made to the drawings in which like reference numerals indicate identical or corresponding parts throughout the several views.

[0043] The disclosed devices, methods, and systems describe the integration of a micro-hole array plate of a beam splitter with the extractor electrode of a Schottky TFE emitter.

[0044] Aspects of the present disclosure describe a Schottky TFE emitter with integrated beam splitter (IBS_TFE), which includes a beam splitter held away from the top of the Schottky TFE emitter's extractor faceplate by a standoff. Electron microscopes using the IBS_TFE benefit from improved resolution, image acquisition speed, and throughput (area scanned and imaged per unit time). The IBS_TFE can be used to generate multi-beam sources for multi-beam scanning electron microscopes and similar inspection tools.

[0045] The IBS_TFE produces a multi-beam source of electrons with high total beam current in multiple beams, along with low energy spread and trajectory deviation.

[0046] Figure 3 is a schematic diagram showing a beam splitter integrated with the faceplate of a Schottky TFE emitter extractor in one embodiment, and is a schematic diagram showing the physical structure of IBS_TFE300 (a beam splitter integrated with a Schottky thermal field emission (TFE) source). The Schottky TFE emitter 304 includes an extractor 306 having a tip 305, a suppressor 307, and a faceplate 308. The suppressor 307 is an electrode inside the Schottky TFE emitter 304 that prevents stray thermionic emission from passing through the extractor hole and down the column. The tip 305 is at the center of the suppressor 307. An electron beam 316 is generated at the tip 305. A beam splitter 314 and its standoff 309 (support member) are attached to the faceplate 308 of the extractor 306, in which an array of micro-holes 415 (shown in FIG. 4) are formed. The beam splitter 314 has a micro-hole array plate 315. The micro-hole array plate 315 is formed with a micro-hole array consisting of a plurality of micro-holes 415 (shown in FIG. 4). The beam splitter 314 splits the electron beam 316 into a plurality of split beams 318. Specifically, the partial beams of electron beam 316 that pass through micro-holes 415 formed in micro-hole array plate 315 become split beams 318. Beam splitter 314 and standoff 309 are axially aligned with the holes in TFE extractor 306. Condenser lens 322 focuses split beams 318 as they leave beam splitter 314. For clarity, FIG. 3 does not show the electronics and lenses that guide split beams 318 to the target after they pass through micro-holes 415 in beam splitter 314 (beam splitter array).

[0047] In a non-limiting example, the potential difference between the faceplate 308 of the extractor 306 and the beam splitter 314 may be about -100 volts, which adds a slight amount of focus field to the split beam 318. The IBS_TFE is integrated as a unit during Schottky TFE emitter fabrication. The micro-hole array plate that makes up the beam splitter is provided with voltage contacts to vary the voltage to obtain the highest beamlet current.

[0048] In a non-limiting example, the standoff 309 can hold the beam splitter 314 at a height H of 0.5 mm to 2 mm above the extractor 306. The standoff 309 may have a cylindrical or ring-like geometry with a diameter equal to or less than that of the extractor 306. The faceplate 308 of a typical commercially available extractor 306 has an outer diameter of about 12.5 mm, a central hole diameter of 0.4 mm, and a thickness of about 1 mm. The standoff 309 is a ring-like metal part that is aligned with the center point of the extractor hole. In a non-limiting example, the ring has an outer diameter of about 8 mm, a width (radially from the inner surface of the ring to the outer surface) of about 1 mm, and a height of about 0.3 mm to 0.5 mm.

[0049] In an embodiment, the standoff 309 may be formed from a conductive material. A non-limiting example of a conductive material is a metal alloy, such as titanium-zirconium-molybdenum (TZM). TZM has a higher recrystallization temperature, higher creep strength, and higher tensile strength than pure unalloyed molybdenum. TZM has a low thermal conductivity (0.48) and therefore does not conduct heat from the extractor faceplate to the beam splitter. Excessive heat at the beam splitter causes the beam splitter to deflect, distorting the trajectories of the split beams. Furthermore, excessive heat can cause the split beams to diverge and / or interfere with each other after exiting the beam splitter, thereby reducing the amount of energy of the split beams that reach the target.

[0050] In one aspect of the disclosure, the standoff 309 may be formed from a conductive high resistance material, such as a resistive ceramic. In a non-limiting example, the resistive ceramic may be alumina and similar to Kyocera AH100A available from Kyocera International, 49070 Milmont Drive, Fremont, Calif., USA. The resistive ceramic is made from a sintered body of ceramic material with conductive particles distributed throughout the matrix to provide a 100% active, non-inductive resistor. The resistive ceramic is chemically inert. The resistive ceramic can withstand high energy and voltage at the high temperatures desired for the standoff 309 near the TFE tip 305, which have temperatures on the order of 1800K. The use of a high resistance ceramic establishes a potential difference between the extractor 306 and the beam splitter 314 (beam splitter array), such that incident electrons intercepted by the beam splitter 314 make the beam splitter 314 negative with respect to the potential of the extractor 306. This benefits the IBS_TFE because the hole in the beam splitter 314 becomes a positive electrostatic microlens, thereby focusing the incident electrons onto the hole, thus further increasing the current through the hole.

[0051] 4A is a schematic diagram showing an array of microholes in a rectangular beam splitter in one embodiment, and one form of beam splitter 414 in the IBS_TFE. In FIG. 4A, the rectangular beam splitter 414 is shown as an example of the beam splitter 314 in FIG. The micro-hole array plate 315 of the beam splitter 414 is formed with a 3×3 array of micro-holes 415. The micro-holes 415 are formed very precisely and are fabricated from a material that can withstand high temperatures without buckling or damage. In a non-limiting example, the diameter of the micro-holes 415 ranges from 10 microns to 120 microns. The material of the beam splitter 414 with the micro-hole array plate 315 may be the same material as the standoffs 309 or a different material. Micro-holes can be machined into the TZM alloy sheet with diameters as small as 10 microns, which may increase the number of split beams exiting the array and may decrease the final focused beamlet spot size, i.e., SEM resolution. The size of the micro-holes 415 is determined by the current required when each beamlet hits the target.

[0052] FIG. 4B is a schematic diagram of a circular beam splitter having an array of equally spaced micro holes in a modified embodiment. FIG. 4B shows a circular beam splitter 414 as an example of the beam splitter 314 in FIG. 3. The diameter of each micro hole 415 increases as the distance from its center increases. FIG. 4B is also a schematic diagram showing a second form (modification) of the beam splitter 414, in which a circular beam splitter array is formed in the micro hole array plate 315 of the beam splitter 414, with multiple micro holes 415 that range from small holes in the center to large holes on the periphery through increasing sizes. Although not shown, in the alternative, the multiple microholes 415 may range from a larger hole in the center to a smaller hole on the periphery through a reduction in size.

[0053] FIG. 4C is a schematic diagram of a circular beam splitter with a rectangular 5×5 array of micro-holes with increasing diameter from the center to the periphery of the beam splitter in another variation of an embodiment. In FIG. 4C, a variation of a circular beam splitter 414 is shown as an example of the beam splitter 314 of FIG. 3. FIG. 4C is also a schematic diagram of a third form of beam splitter 414, in which the micro-hole array plate 315 of the beam splitter 414 is circular, but the area in which the micro-hole array is formed is rectangular, with the holes of the micro-holes 415 becoming gradually larger in size. The holes may range from 10 microns to 120 microns and are application specific. The rectangular array shown is a 5×5 array.

[0054] In a non-limiting example, the material of the beam splitter 314 (beam splitter array) may be stainless steel. In another non-limiting example, the material may be a TZM alloy. In a further non-limiting example, the material may be a machinable conductive ceramic material.

[0055] Although Figure 4A shows a 3x3 array of micro-holes 415, Figure 4B shows multiple radially arranged micro-holes 415, and Figure 4C shows a 5x5 array of micro-holes 415, the number of micro-holes 415, their diameters, and the array pattern are not limited. For example, a 4x4 array, 4x5, 5x5, or larger array may be used depending on the constraints of the lens barrel. The array may have a non-rectangular, application-specific layout.

[0056] The split beams 318 (FIG. 3) exiting the microhole array are beam-formed by downstream optics and electrodes to strike a target (not shown). A large number of simultaneously scanning split beams 318 increases the acquisition speed, i.e., throughput, of the SEM. However, due to limitations on the size of the beamlets, if the beamlets are too small, there may not be enough current in the beamlets to provide a detectable SEM signal at a given noise level.

[0057] The beamlets 318 (split beams) exiting the micro-hole array carry lower current than the primary beam exiting the Schottky TFE emitter by an amount proportional to the number of holes in the micro-hole array (array transparency). Separation of the beamlets reduces the Boersch effect in the individual beamlets, allowing for less energy spread in each beamlet, and therefore less chromatic aberration.

[0058] Figure 5 is a schematic diagram showing a Schottky TFE emitter with integrated beam splitter and extractor in one embodiment. Figure 5 also shows the integration of a Schottky TFE emitter 504 with an IBS_TFE set 513 of the present disclosure. A micro-hole array of a plurality of micro-holes 515 is formed in the micro-hole array plate of the beam splitter 514. The IBS_TFE set 513 is integrated with the extractor faceplate 508 (extractor surface) of the Schottky TFE emitter 504. In one embodiment, the standoff 509 of the IBS_TFE set 513 may be bonded to the extractor faceplate 508 by welding or brazing. In this embodiment, the standoff 509 may be a resistive ceramic that creates a potential difference between the extractor faceplate 508 and the micro-hole array plate of the beam splitter 514. In another embodiment, the extractor faceplate 508 and the standoff 509 are machined from the same material, but are later joined as separate parts. The extractor and / or the standoff may be manufactured from TZM alloy, titanium, or stainless steel. In another embodiment, the standoff and the beam splitter may be manufactured as an integral part from the same piece of material, such as TZN alloy or titanium.

[0059] The IBS_TFE set 513 of the present disclosure places the emission of the Schottky TFE emitter close to the Schottky extractor electrode so that maximum current passes through the array of micro-holes.

[0060] Figure 6A is a schematic diagram showing the integration of a Schottky TFE emitter with standoffs 609 in one embodiment. Figure 6A also shows the integration of an extractor faceplate, standoffs, and beamsplitter array in a cylindrical configuration. In FIG. 6A, the standoff 609 is shown as a cross section of a hollow cylinder. The standoff 609 is shown integrated with the extractor faceplate 608 of the Schottky TFE emitter. 608′ represents the beam aperture in the center of the extractor 608. The standoff 609 and the extractor faceplate 608 may be integrated by welding or brazing. The micro-hole array formed in the micro-hole array plate of the beam splitter 614 contains an array of micro-holes 615 and is integrated with the top end of the standoff 609 along axis A. The micro-hole array plate that becomes the beam splitter 614 may be fused or attached by brazing or welding to the top end of the standoff 609 or may be formed as a single unit with the standoff 609.

[0061] Figure 6B is a schematic diagram showing a mounting feature for integrating a beamsplitter array with a standoff in one embodiment, and a mounting feature machined into the top end of the standoff 609 to form an indented shelf 619. The micro-hole array plate 616 that makes up the beam splitter 614 abuts the indented shelf 619 and may be secured thereto by welding, friction stir welding, clamping, brazing, soldering with high temperature solder, or the like.

[0062] The standoff 609 may be the same or a different material as the extractor faceplate 608. The standoff 609 may be a metal alloy, for example TZM. If the extractor (extractor faceplate 608) is a first material, for example stainless steel, and the standoff 609 is a second highly resistive material, for example resistive ceramic AH100A, the potential of the extractor is higher than the potential at the beam splitter 614 due to the potential drop across the standoff 609. This potential may result in a lens effect on the beamlets (electrostatic focusing).

[0063] In operation, an incident electron beam is emitted by the Schottky TFE emitter, which passes through holes 608' (FIG. 6A) in the TFE extractor electrode and immediately impinges on an array of micro-holes 615 located close to the extractor electrode. A beam splitter 614 with a micro-hole array plate 616 is supported by standoffs 609, which provide electrical and thermal contact between the micro-hole array plate 616 and the extractor electrode. The standoffs 609 may act as built-in resistors that provide a voltage bias between the beam splitter 614 and the extractor (extractor faceplate 608). This voltage bias causes the micro-holes 615 in the beam splitter 614 to become positive electrostatic micro-lenses, which focuses the incident electrons into the holes and further increases the current passing through the holes.

[0064] The IBS_TFE of this disclosure brings the beam splitter closer to the Schottky emitter tip and integrates the beam splitter into the Schottky TFE emitter. The advantages are reduced energy spread of the multiple individual beamlets (split beams), minimal trajectory deviation, and increased current.

[0065] The advantage of the IBS_TFE of the present disclosure over existing technology is that maximum current is delivered to each individual beamlet with the lowest possible energy spread and trajectory deviation in the multiple beamlets, which benefits the focusing quality and resolution of the electron beam system. Furthermore, because the beam spread is minimal, focusing electrodes (e.g., 110, 112, FIG. 1) can be eliminated.

[0066] One embodiment of the present disclosure describes a beam splitter integrated with the extractor faceplate of a Schottky TFE emitter.

[0067] One embodiment of the present disclosure describes a beam splitter that is spaced from the extractor faceplate of a Schottky TFE emitter by a standoff.

[0068] One embodiment of the present disclosure describes a beam splitter that is spaced from the extractor faceplate of a Schottky TFE emitter by a standoff, where the standoff supports the beam splitter above the extractor at a distance of 0.5mm to 2mm.

[0069] One embodiment of the present disclosure describes a beam splitter that is spaced from the extractor faceplate of a Schottky TFE emitter by a standoff, where the standoff has a hollow cylindrical geometry.

[0070] One embodiment of the present disclosure describes a beam splitter having an array of microholes.

[0071] One embodiment of the present disclosure describes a beam splitter with a 3×3 array of microholes.

[0072] One embodiment of the present disclosure describes a beam splitter with a 4x4 array of microholes.

[0073] One embodiment of the present disclosure describes a beam splitter with a 5×5 array of microholes.

[0074] One embodiment of the present disclosure describes a beam splitter that includes an array of microholes, where the diameter of each microhole ranges from 10 microns to 120 microns.

[0075] One embodiment of the present disclosure describes a beamsplitter that includes an array of microholes configured such that the diameter of the microholes increases from the center of the array to the periphery of the array.

[0076] One embodiment of the present disclosure describes a beamsplitter that includes an array of microholes configured such that the diameter of the microholes decreases from the center of the array to the periphery of the array.

[0077] One embodiment of the present disclosure describes a beamsplitter that includes an array of microholes, where the diameter of the microholes varies from 10 microns to 120 microns in a pattern where the diameter is smaller toward the center of the array and larger near the periphery of the array.

[0078] One embodiment of the present disclosure describes a beam splitter array plate having a rectangular or circular or hexagonal shape.

[0079] One embodiment of the present disclosure describes a rectangular shaped beamsplitter array.

[0080] One embodiment of the present disclosure describes a circular shaped beamsplitter array.

[0081] One embodiment of the present disclosure describes a hexagonally shaped beamsplitter array.

[0082] One embodiment of the present disclosure describes a beamsplitter array that is octagonally shaped.

[0083] One embodiment of the present disclosure describes a beam splitter that includes an array of microholes, where the diameter of each microhole ranges from 10 microns to 120 microns.

[0084] One embodiment of the present disclosure describes a beam splitter that includes an array of microholes, where the microholes are formed by microdrilling.

[0085] One embodiment of the present disclosure describes a beamsplitter that includes an array of microholes, where the beamsplitter is fabricated from a resistive, machinable ceramic material and the microholes are formed by chemical etching.

[0086] One embodiment of the present disclosure describes a beam splitter integrated with the standoff and extractor faceplate of a Schottky TFE emitter.

[0087] One embodiment of the present disclosure describes a beam splitter integrated with a standoff and extractor faceplate of a Schottky TFE emitter, where the beam splitter, standoff, and extractor faceplate are fabricated from stainless steel.

[0088] One embodiment of the present disclosure describes a beam splitter integrated with a standoff and extractor faceplate of a Schottky TFE emitter, where the beam splitter, standoff, and extractor faceplate are fabricated from a conductive ceramic material.

[0089] One embodiment of the present disclosure describes a beam splitter integrated with a standoff and extractor faceplate of a Schottky TFE emitter, where the beam splitter, standoff, and extractor faceplate are fabricated from aluminum nitride or alumina.

[0090] One embodiment of the present disclosure describes a beam splitter integrated with a Schottky TFE emitter standoff and extractor faceplate, where the standoff is fabricated from a high resistivity metal.

[0091] One embodiment of the present disclosure describes a beam splitter integrated with a standoff and extractor faceplate of a Schottky TFE emitter, where the beam splitter, standoff, and extractor faceplate are fabricated from tungsten carbide.

[0092] Embodiments of the present disclosure may also be as described in the parenthetical description below.

[0093] (1) A beam splitter integrated with a thermal field emission (TFE) source, the beam splitter comprising: a Schottky TFE emitter having an extractor faceplate; a standoff integrated with the extractor faceplate; and a micro-hole array plate integrated with the standoff and positioned opposite the extractor faceplate, the micro-hole array plate having a plurality of micro-holes formed therein.

[0094] (2) A beam splitter as in (1), in which the extractor faceplate, the standoffs, and the microhole array plate are fabricated from the same material.

[0095] (3) A beam splitter of either (1) or (2), the same material being titanium-zirconium-molybdenum, titanium, or stainless steel.

[0096] (4) A beam splitter according to any one of (1) to (3), wherein the material is a machinable conductive ceramic material.

[0097] (5) The beam splitter of any one of (1) to (4), wherein the machinable conductive ceramic material is alumina.

[0098] (6) The beam splitter of (1), wherein the extractor faceplate, the standoff, and the microhole array plate are fabricated from the same or different materials.

[0099] (7) The beamsplitter of any one of (1) or (6), wherein the extractor faceplate is fabricated from stainless steel, the standoffs are fabricated from a high resistance material, and the micro-hole array plate is fabricated from a machinable ceramic material.

[0100] (8) The beam splitter of any one of (1) and (4) to (6), wherein the extractor faceplate is fabricated from stainless steel and the standoffs and the microhole array plate are fabricated from a machinable conductive ceramic material.

[0101] (9) The beam splitter of any one of (1) and (4) to (7), wherein the machinable ceramic material is alumina.

[0102] (10) The beam splitter of (1), further comprising a mounting feature located at a second end of the standoff, the mounting feature configured to connect the standoff to the micro-hole array plate.

[0103] (11) The standoff separates the microhole array plate from the extractor faceplate by a distance ranging from 0.5 mm to 2 mm.

[0104] (12) The beam splitter of (1), wherein the microhole array is a 3x3 array, a 4x5 array, or a 5x5 array.

[0105] (13) A beam splitter as in (1), wherein each of the microholes has the same diameter, the diameter being between 10 microns and 120 microns.

[0106] (14) A beam splitter as in (1), wherein the microholes increase in size from the center of the beam splitter to the outer periphery of the beam splitter.

[0107] (15) A method for integrating a beam splitter with an extractor faceplate of a Schottky TFE emitter, comprising the steps of integrating a first end of a standoff with the extractor faceplate, forming a micro-hole array plate by forming micro-holes in a substrate, and attaching the micro-hole array plate to a second end of the standoff, the second end being opposite to the first end, and the standoff supporting the micro-hole array plate at a distance of 0.5 mm to 2 mm above the extractor faceplate. Note that the order of the step of integrating the first end of the standoff with the extractor faceplate and the step of forming micro-holes in the micro-hole array plate may be reversed.

[0108] (16) The method of integrating a beam splitter of (15), further comprising the steps of: integrating a first end of the standoff by welding the standoff to the extractor faceplate; or integrating a first end of the standoff by brazing the standoff to the extractor faceplate; or integrating a first end of the standoff by machining a groove inside the first end of the standoff, inserting the extractor faceplate into the groove, and welding the extractor faceplate to the standoff.

[0109] (17) The beam splitter integration method of (15), further comprising the step of attaching the micro hole array plate to the standoffs by welding or friction stir welding or soldering or clamping or bonding with a thermal adhesive.

[0110] (18) The method for integrating a beam splitter according to (15), wherein in the step of forming a microhole array plate, a plurality of microholes are formed in the substrate by microdrilling, and the diameters of the microholes increase from the center of the microhole array plate toward the outer periphery of the microhole array plate.

[0111] Or (19) The method for integrating a beam splitter according to (15), wherein in the step of forming the above-mentioned micro-hole array plate, the micro-holes in the micro-hole array plate are formed by micromachining, and the micromachining includes micro-drilling or chemical etching.

[0112] (20) A multi-beam forming method for forming a plurality of electron beams, comprising the steps of: supplying power to a Schottky thermal field emission (TFE) to generate an electron beam at an extractor aperture; supplying a voltage to an extractor contact; and splitting the electron beam into a plurality of electron beams by passing the electron beam through a micro-hole array plate having a plurality of micro-holes, wherein the micro-hole array plate is supported 0.5 mm to 2 mm above the extractor aperture by a standoff integrated with the extractor aperture.

[0113] Numerous modifications and variations of the present invention are possible in light of the above teachings, and it is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.

[0114] Further, although the description of the device configuration, control method, and other parts not directly necessary for the explanation of the present invention have been omitted, the required device configuration and control method can be appropriately selected and used.

[0115] In addition, all thermal field emitters, multi-beam forming devices, and multi-beam generating methods for electron beam tools that include elements of the present invention and can be appropriately modified by those skilled in the art are included in the scope of the present invention. [Explanation of symbols]

[0116] 102 FEG 104 Schottky TFE Emitter 106 Suppressor 108 Extractor 105 Chips 110,112 electrode 114 Beam splitter 116 Electron Beam 118 Split Beam 202 FEG 204 Schottky TFE emitter 205 Chips 206 Aperture Plate 208 Extractor 214 Beam splitter 216 Electron Beam 218 Split Beam 220 Collimator Lens 222 Condenser Lens 224 Blanka Opening 226 Beam Stopper 228 Diverging Beam 230 Projection Lens 234 Target 300 IBS_TFE 304 Schottky TFE Emitter 305 Chip 306 Extractor 307 Suppressor 308 Faceplate 309 Standoff 318 Split Beam 314,414 Beam splitter 315 Microhole Array Plate 316 Electron Beam 322 Condenser Lens 415 Micro Hole 504 Schottky TFE Emitter 508 Extractor Faceplate 509 Standoff 513 IBS_TFE set 608 Extractor Faceplate 608' opening 609 Standoff 614 Beam splitter 615 Micro Hole 616 Microhole Array Plate 619 Shelf

Claims

1. a Schottky thermal field emission (TFE) emitter having an extractor faceplate; a standoff integral with said extractor faceplate; a micro-hole array plate, integral with the standoffs and positioned opposite the extractor faceplate, the micro-hole array plate having a plurality of micro-holes; 1. A beam splitter integrated with a Schottky thermal field emission (TFE) source, comprising:

2. 2. The beam splitter integrated with a Schottky thermal field emission (TFE) source of claim 1, wherein the extractor faceplate, the standoffs, and the micro-hole array plate are fabricated from the same material.

3. 3. The beam splitter integrated with a Schottky thermal field emission (TFE) source of claim 2, wherein said same material is titanium-zirconium-molybdenum, titanium, or stainless steel.

4. 3. The beam splitter integrated with a Schottky thermal field emission (TFE) source as recited in claim 2, wherein said same material is a machinable conductive ceramic material.

5. 5. The beamsplitter integrated with a Schottky thermal field emission (TFE) source as recited in claim 4, wherein said machinable conductive ceramic material is alumina.

6. 2. The beam splitter integrated with a Schottky thermal field emission (TFE) source of claim 1, wherein the extractor faceplate, the standoff, and the micro-hole array plate are fabricated from the same or different materials.

7. 7. The beamsplitter integrated with a Schottky thermal field emission (TFE) source of claim 6, wherein the extractor faceplate is fabricated from stainless steel, the standoffs are fabricated from a resistive material, and the micro-hole array plate is fabricated from a machinable ceramic material.

8. 7. The beamsplitter integrated with a Schottky thermal field emission (TFE) source of claim 6, wherein the extractor faceplate is fabricated from stainless steel, and the standoffs and the micro-hole array plate are fabricated from a machinable conductive ceramic material.

9. 9. The beamsplitter integrated with a Schottky thermal field emission (TFE) source of claim 8, wherein said machinable ceramic material is alumina.

10. a first end of the standoff is integral with the extractor faceplate; 10. The beamsplitter integrated with a Schottky thermal field emission (TFE) source of claim 1, further comprising a mounting feature disposed at a second end of the standoff and configured to connect the standoff to the micro-hole array plate.

11. 2. The beam splitter integrated with a Schottky thermal field emission (TFE) source of claim 1, wherein the standoff spaces the micro-hole array plate from the extractor faceplate by 0.5 mm to 2 mm.

12. 2. The beam splitter integrated with a Schottky thermal field emission (TFE) source as claimed in claim 1, wherein the micro-hole array of the micro-hole array plate is a 3x3 array, a 4x5 array, or a 5x5 array.

13. 2. The beam splitter integrated with a Schottky thermal field emission (TFE) source as recited in claim 1, wherein each of the micro-holes in the micro-hole array plate has the same diameter, and the diameter is between 10 microns and 120 microns.

14. 2. The beamsplitter integrated with a Schottky thermal field emission (TFE) source of claim 1, wherein the microholes increase in size from the center of the beamsplitter to the outer periphery of the beamsplitter.

15. 1. A beam splitter integration method for integrating a beam splitter with an extractor faceplate of a Schottky thermal field emission (TFE) emitter, comprising: integrating a first end of a standoff into the extractor faceplate; forming microholes in a substrate to form a microhole array plate; attaching the micro hole array plate to a second end of the standoff; Equipped with the second end is opposite the first end; the standoffs support the micro-hole array plate at a distance of 0.5 mm to 2 mm above the extractor faceplate; A method for integrating a Schottky thermal field emission (TFE) source and a beam splitter, comprising:

16. or, welding the first end of the standoff to the extractor faceplate; or, integrally mounting the first end of the standoff to the extractor faceplate by brazing the standoff to the extractor faceplate; integrally integrating the first end of the standoff by machining a groove therein, inserting the extractor faceplate into the groove, and welding the extractor faceplate to the standoff; 16. The method of claim 15, further comprising:

17. 16. The method of claim 15, further comprising attaching the micro-hole array plate to the standoffs by welding, friction stir welding, soldering, clamping, or bonding with a thermal adhesive.

18. In the step of forming the microhole array plate, a plurality of microholes are formed in the substrate by microdrilling; 16. The method of claim 15, wherein the diameter of the micro-holes increases from the center of the micro-hole array plate to the outer periphery of the micro-hole array plate.

19. In the step of forming the micro-hole array plate, the micro-holes in the micro-hole array plate are formed by micromachining; The micromachining comprises microdrilling or chemical etching.

16. The method of integrating a Schottky thermal field emission (TFE) source and a beam splitter as claimed in claim 15.

20. 1. A multi-beam forming method for forming a plurality of electron beams, comprising: powering a Schottky thermal field emission (TFE) emitter to generate an electron beam at an extractor aperture; applying a voltage to the extractor contacts; splitting the electron beam into multiple electron beams by passing the electron beam through a micro-hole array plate comprising a plurality of micro-holes, the micro-hole array plate being supported 0.5 mm to 2 mm above an extractor faceplate by standoffs integral with the extractor faceplate; A multi-beam forming method comprising:

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