EP1145272A2 - Improved alignment of a thermal field emission electron source and application in a microcolumn - Google Patents
Improved alignment of a thermal field emission electron source and application in a microcolumnInfo
- Publication number
- EP1145272A2 EP1145272A2 EP99954854A EP99954854A EP1145272A2 EP 1145272 A2 EP1145272 A2 EP 1145272A2 EP 99954854 A EP99954854 A EP 99954854A EP 99954854 A EP99954854 A EP 99954854A EP 1145272 A2 EP1145272 A2 EP 1145272A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- source
- emission
- microcolumn
- deflection
- electrode
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 238000000034 method Methods 0.000 claims abstract description 11
- 230000008878 coupling Effects 0.000 claims 1
- 238000010168 coupling process Methods 0.000 claims 1
- 238000005859 coupling reaction Methods 0.000 claims 1
- 238000010894 electron beam technology Methods 0.000 abstract description 18
- 238000011065 in-situ storage Methods 0.000 abstract description 2
- 238000005516 engineering process Methods 0.000 description 6
- 239000012528 membrane Substances 0.000 description 5
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 4
- 230000003287 optical effect Effects 0.000 description 4
- 238000007689 inspection Methods 0.000 description 3
- 229910052710 silicon Inorganic materials 0.000 description 3
- 239000010703 silicon Substances 0.000 description 3
- RZVAJINKPMORJF-UHFFFAOYSA-N Acetaminophen Chemical compound CC(=O)NC1=CC=C(O)C=C1 RZVAJINKPMORJF-UHFFFAOYSA-N 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000003384 imaging method Methods 0.000 description 2
- 238000001459 lithography Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 239000005297 pyrex Substances 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 2
- 229910052721 tungsten Inorganic materials 0.000 description 2
- 239000010937 tungsten Substances 0.000 description 2
- 229910000979 O alloy Inorganic materials 0.000 description 1
- 229910001080 W alloy Inorganic materials 0.000 description 1
- 230000006978 adaptation Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 229910003460 diamond Inorganic materials 0.000 description 1
- 239000010432 diamond Substances 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 238000000609 electron-beam lithography Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- WHJFNYXPKGDKBB-UHFFFAOYSA-N hafnium;methane Chemical compound C.[Hf] WHJFNYXPKGDKBB-UHFFFAOYSA-N 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000004377 microelectronic Methods 0.000 description 1
- 238000001020 plasma etching Methods 0.000 description 1
- 238000004574 scanning tunneling microscopy Methods 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
- 230000005641 tunneling Effects 0.000 description 1
- 235000012431 wafers Nutrition 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/26—Electron or ion microscopes; Electron or ion diffraction tubes
- H01J37/28—Electron or ion microscopes; Electron or ion diffraction tubes with scanning beams
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/02—Details
- H01J37/04—Arrangements of electrodes and associated parts for generating or controlling the discharge, e.g. electron-optical arrangement or ion-optical arrangement
- H01J37/06—Electron sources; Electron guns
- H01J37/073—Electron guns using field emission, photo emission, or secondary emission electron sources
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
- H01J2237/06—Sources
- H01J2237/063—Electron sources
- H01J2237/06308—Thermionic sources
- H01J2237/06316—Schottky emission
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
- H01J2237/15—Means for deflecting or directing discharge
- H01J2237/1501—Beam alignment means or procedures
Definitions
- the present invention relates to charged particle imaging using electron beams and in particular a method and system for aligning the field emission beam.
- Microcolumns An effort to improve electron-beam systems has resulted in miniature electron-beam microcolumns ("microcolumns").
- Microcolumns ire based on microfabricated electron “optical” components and field emission sources operating under principles similar to scanning tunneling microscope (STM) aided alignment principles, also called STM aligned field emission (SAFE).
- STM scanning tunneling microscope
- SAFE STM aligned field emission
- the alignment principles used by microcolumns are similar to STMs in that a precision X-Y-Z positioner is used to control a sharp tip, and to utilize the emission from the tip to measure the position of the tip.
- Microcolumns are discussed in general in the publication "Electron-Beam Microcolumns for Lithography and Related Applications," by T.
- microcolumns are formed of high aspect ratio micromechanical structures, including microlenss and deflectors.
- STM positioner is feasible for positioning the field emission electron beam, it is most useful in prototype systems.
- the STM mechanical alignment requires a complex mechanical structure and the operation is not as precise as desired. Further, it is desirable to dynamically correct for positional drift of the emission electron beam during operation of the field emission system. It thus would be desirable to achieve alignment of the field emission beam during operation of the microcolumn without utilizing mechanical structures.
- a method and system for aligning a source in an electron-beam microcolumn in situ includes a split suppressor cap for a miniature Schottky electron or other field emission source.
- the split suppressor cap is segmented into four or more separate electrode elements, which can be independently controlled with separate deflection voltages to scan the electron beam without mechanical movement.
- the electronic control also allows for dynamic correction of the field emission beam drift during operation of the microcolumn.
- FIG. 1 is an exploded perspective view of a microcolumn which can incorporate the present invention.
- FIG. 2 is an exploded perspective view of a microcolumn source and microlens which can incorporate the present invention.
- FIG. 3 is a side sectional view of a miniature Schottky electron source.
- FIG. 4 is a side view of an embodiment of a split suppressor cap for the electron source of the present invention.
- FIG. 5 is a top view of the suppressor cap of FIG. 4.
- a prior art microcolumn is designated generally by the reference numeral 10, illustrated with a grid sample 12 and a channeltron electron detector 14 which is utilized to generate scanning transmission electron microscope (STEM) images from electron transparent samples.
- the microcolumn includes an electron source (not illustrated), which can be a miniature cold-field or Schottky emitter having a field emitter tip 16.
- the tip 16 can be a Zr/O/W Schottky-type emitter tip or if a cold emitter tip, could be a single crystal tungsten, hafnium carbide or diamond tip.
- the tip 16 preferably is mounted on a positioner 18, such as a three axis STM type X-Y-Z positioner.
- the positioner 18 has a range of movement on the order of tens of microns up to about one (1) millimeter (mm) in each axis.
- the positioner 18 has a nanometerscale positioning accuracy capability and is utilized to align the tip 16 with an electron optical column 20.
- the column 20 can have a length on the order of three and one-half (3.5) mm.
- the tip 16 is aligned with a five (5) micron aperture 22 for example purposes, in an extractor 24.
- the extractor 24 is combined with an anode 26, having an aperture 28 on the order of one hundred (100) microns to form a selectively scaled dual electrode source lens 30 .
- the resulting electron beam 32 is directed to a beam limiting aperture 34 in an aperture member 36.
- the aperture 34 is on the order of several microns, illustrated as two and one-half (2.5) microns, in diameter. The spacing and aperture size selected determine the convergence of the resulting e-beam 38 at the grid 12.
- the beam 38 is passed through a beam deflector 40 which can be a single unit or a multiple unit octupole scanner/stigmator.
- the deflector 40 is utilized to deflect or scan the beam 38 across the sample 12.
- a multiple electrode Einzel lens 42 focuses the beam 38 onto the sample 12 at a working distance 44 of one (1) to two (2) mm.
- the lens 42 can, for example, include three electrodes 46, 48, 50, each having an aperture 52 with a diameter on the order of two hundred (200) microns.
- the microcolumn 10 also can include an electron detector 54, which can be a microchannel plate electron detector for secondary and backscattered electrons or a metal- semiconductor detector for low energy backscattered electrons.
- the microcolumn 10 can be operated to produce a 1 KeV beam 38.
- FIG. 1 illustrates merely one example of many possible field emission sources and electron optical columns that may be utilized in the microcolumn 10.
- additional field emission sources and electron optical columns that may be used in the microcolumn 10 in general, see the following articles and patents: "Experimental Evaluation of a 20x20 mm Footprint Microcolumn", by E. Kratschmer et al., Journal of Vacuum Science Technology, Bulletin 14 (6), pp. 3792-96, Nov./Dec. 1996; "Electron Beam Technology - SEM to Microcolumn," by T.H.P. Chang et al., Microelectronic Engineering 32, pp.
- the source 30 includes a plurality of silicon wafers or chips 60, 62 and 64, which are spaced apart by one hundred (100) to five hundred (500) micron thick insulating layers 66 and 68. The layers 60 to 68 are not drawn to scale.
- the layers 66 and 68 are generally formed from glass, such as glass sold under the trademark, Pyrex.
- the layers 60 to 68 then are precisely aligned and bonded together to form the source 30, typically by electrochemical anodic bonding.
- the silicon chips Prior to the bonding process, the silicon chips are processed with electron beam lithography and reactive-ion etching to form a respective silicon membrane 70, 72, and 74 in each of the chips 60, 62 and 64.
- the required beam apertures, such as the respective apertures 22, 28 and 34, then are formed in the membranes 70, 72 and 74.
- the membranes 70, 72 and 74 are on the order of one (1) to two (2) microns thick.
- the membranes 70, 72 and 74 and the apertures 22, 28 and 34 form the elements 24, 26 and 36 of the lens 30.
- the electrodes 46, 48 and 50 of the lens 42 are formed with central silicon membranes 76, 78 and 80, in which are formed respective apertures 52.
- the lens 42 includes a plurality of Pyrex insulating layers 84 and 86, which also include apertures 88 and 90, which are larger in diameter than the apertures 52.
- the layers 46, 48, 50, 84 and 86 again are aligned and typically bonded together to form the lens 42.
- a miniature Schottky electron source 100 is illustrated, which can be the emitter source for the microcolumn 10 and can include the emitter tip 16.
- the electron source 100 includes a suppressor cap 102.
- the cap 102 is mounted over an insulator body 104, which encompasses and insulates a pair of conductors 106, 108 which support and supply the power to the tip 16.
- the tip 16 preferably can be a Zr/O/W alloy tip and is mounted on a miniature filament 110 enclosed within the suppressor cap 102.
- the tip 16 extends from the suppressor cap 102 through an opening 112.
- a conventional Schottky electron source typically would have length L of about twenty (20) millimeters (mm) and a width (or diameter) W of about seventeen (17) mm.
- the electron source 100 has a length L of thirteen and seven tenths (13.7) mm and a width W of four (4) mm.
- a conventional source would have a one hundred and twenty-five (125) micron filament, but the electron source 100 has a seventy five (75) micron tungsten filament.
- the smaller filament size enables the electron source 100 to operate at a heating power of one and one half (1.5) to one and eight tenths (1.8) watts of heating power versus two and one-half (2.5) to three and one half (3.5) watts for a conventional electron source.
- the STM positioner 18 can be utilized to mechanically adjust the positioning of the electron source 100 and hence the tip 16. This physical alignment is not optimal for a number of reasons.
- one embodiment of a suppressor cap of the present invention is designated by the reference numeral 114.
- the beam 116 is illustrated as being perfectly aligned with the aperture 22 in the extractor 24, but in fact this required optimum alignment can be difficult to achieve.
- the aperture 22 has a diameter on the order of a few microns and the tip 16 has an operating distance 118 from the aperture 22 on the order of one hundred (100) microns.
- the suppressor cap 102 or 114 reduces the number of thermionically emitted electrons from the filament 110 and from the shank 120 (see FIG. 3) of the tip 16.
- the tip is mechanically centered at the working distance 118 and aligned with the aperture 22.
- the electron source 100 cannot be mechanically aligned in the same manner in the microcolumn 10, because of the assembly procedure required for the microcolumn 10, the significantly smaller dimensions of the electrodes in the source 30 and the overall dimensions of the elements in the microcolumn 10.
- utilization of the STM positioner 18 is feasible, it adds complexity and size to the microcolumn 10, is not as reliable as desired and requires more time than desirable to scan the beam 116 over the large areas, which can be required.
- the beam 116 is illustrated as aligned with the aperture 22, it more likely will be misaligned, such as illustrated by a beam 116'.
- the misaligned beam 116' is totally (as illustrated) or partially directed away from the aperture 22. This causes a total or partial failure of the beam 116' passing through the aperture 22, which when aligned forms a maximum power beam 122 which will become the beam 38 (see FIG. 1).
- the suppressor cap 114 of the present invention solves this alignment/scanning focus problem by utilizing four (4), as illustrated in FIGS. 4 and 5, or more segmented or separated electrodes 124, 126, 128 and 130. Although illustrated and described as a miniature Schottky electron source, the suppressor cap 114 of the present invention can be utilized with any type of thermal field emission source.
- the suppressor voltage, Vs which is utilized to reduce the number of thermionically emitted electrons from the filament 110 and the tip shank 120 is summed with the desired deflection voltages, +V y and +V X applied to each of the electrode segments 124, 126, 128 and 130 such as coupled from a power source (not illustrated) to steer the beam 116 as desired.
- Ramped electrical signals can be applied to the electrodes 124, 126, 128 and 130 to quickly scan the beam 116 over the extractor 24 to locate the optimum operating position of the beam 116.
- the deflection voltages ⁇ V X and ⁇ V y also can be utilized to dynamically correct for drift of the location of the source beam 116, during operation of the electron source 100, such as during operation of the microcolumn 10.
- the deflection voltages can be generated, for example, by a scan generator, essentially as two synchronized ramp waves.
- the position of the beam 116 can be monitored by measuring the beam current incident on the extractor 24, the anode 26 or the limiting aperture 34. Because the deflection required are small and the beam voltage is low, high speed electronics can be utilized to generate the required scan signals.
Landscapes
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Electron Sources, Ion Sources (AREA)
- Electron Beam Exposure (AREA)
Abstract
Description
Claims
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US17661398A | 1998-10-21 | 1998-10-21 | |
US176613 | 1998-10-21 | ||
PCT/US1999/023704 WO2000024030A2 (en) | 1998-10-21 | 1999-10-07 | Improved alignment of a thermal field emission electron source and application in a microcolumn |
Publications (2)
Publication Number | Publication Date |
---|---|
EP1145272A2 true EP1145272A2 (en) | 2001-10-17 |
EP1145272A3 EP1145272A3 (en) | 2002-11-27 |
Family
ID=22645098
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP99954854A Withdrawn EP1145272A3 (en) | 1998-10-21 | 1999-10-07 | Improved alignment of a thermal field emission electron source and application in a microcolumn |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP1145272A3 (en) |
JP (1) | JP2003513407A (en) |
KR (1) | KR20010080286A (en) |
WO (1) | WO2000024030A2 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US10388489B2 (en) | 2017-02-07 | 2019-08-20 | Kla-Tencor Corporation | Electron source architecture for a scanning electron microscopy system |
Families Citing this family (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6288401B1 (en) | 1999-07-30 | 2001-09-11 | Etec Systems, Inc. | Electrostatic alignment of a charged particle beam |
US6512235B1 (en) * | 2000-05-01 | 2003-01-28 | El-Mul Technologies Ltd. | Nanotube-based electron emission device and systems using the same |
US9484179B2 (en) * | 2012-12-18 | 2016-11-01 | General Electric Company | X-ray tube with adjustable intensity profile |
US9793089B2 (en) * | 2013-09-16 | 2017-10-17 | Kla-Tencor Corporation | Electron emitter device with integrated multi-pole electrode structure |
KR20210132599A (en) | 2020-04-24 | 2021-11-04 | 아이엠에스 나노패브릭케이션 게엠베하 | Chargedparticle source |
KR20230005357A (en) * | 2020-06-29 | 2023-01-09 | 주식회사 히타치하이테크 | Electron sources, electron guns, and charged particle beam devices |
EP4095882A1 (en) | 2021-05-25 | 2022-11-30 | IMS Nanofabrication GmbH | Pattern data processing for programmable direct-write apparatus |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3358174A (en) * | 1964-12-18 | 1967-12-12 | Gen Electric | Electron gun having a segmented control electrode |
DE3138896A1 (en) * | 1981-09-30 | 1983-04-14 | Siemens AG, 1000 Berlin und 8000 München | ELECTRONIC OPTICAL SYSTEM WITH VARIO SHAPED BEAM FOR THE GENERATION AND MEASUREMENT OF MICROSTRUCTURES |
US4588928A (en) * | 1983-06-15 | 1986-05-13 | At&T Bell Laboratories | Electron emission system |
-
1999
- 1999-10-07 WO PCT/US1999/023704 patent/WO2000024030A2/en not_active Application Discontinuation
- 1999-10-07 EP EP99954854A patent/EP1145272A3/en not_active Withdrawn
- 1999-10-07 KR KR1020017005019A patent/KR20010080286A/en not_active Application Discontinuation
- 1999-10-07 JP JP2000577692A patent/JP2003513407A/en active Pending
Non-Patent Citations (1)
Title |
---|
See references of WO0024030A2 * |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US10388489B2 (en) | 2017-02-07 | 2019-08-20 | Kla-Tencor Corporation | Electron source architecture for a scanning electron microscopy system |
Also Published As
Publication number | Publication date |
---|---|
WO2000024030A2 (en) | 2000-04-27 |
KR20010080286A (en) | 2001-08-22 |
WO2000024030A3 (en) | 2002-10-10 |
JP2003513407A (en) | 2003-04-08 |
EP1145272A3 (en) | 2002-11-27 |
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