# US 2013/0240751 A1 · Charged Particle Extraction Device and Method of Design There for > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0240751 A1 - Document ID: US20130240751A1 - Status: Published application - Kind: A1 - Application number: 13/780,071 - Filed: 2013-02-28 - Published: 2013-09-19 - Earliest claimed: 2003-10-17 - Assignees: FEI Company - Applicants: Fei Company - Inventors: Roderick Boswell; Orson Sutherland - Web page: https://patentgrep.com/patent/US20130240751A1 ## CPC - H01J 3/00: Details of electron-optical or ion-optical arrangements common to two or more basic types of discharge tubes or lamps - H01J 27/024: {Extraction optics, e.g. grids} - H01J 37/08: Ion sources; Ion guns - H01J 2237/061: Construction - H01J 2237/083: Beam forming - H01J 2237/121: characterised by shape - H01J 2237/31749: Focused ion beam - H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H) ## Abstract The present invention provides a method for extracting a charged particle beam from a charged particle source. A set of electrodes is provided at the output of the source. The potentials applied to the electrodes produce a low-emittance growth beam with substantially zero electric field at the output of the electrodes. ## Claims ### Claim 1 A low emittance growth extractor for extracting particles from a particle source to form a charged particle beam, comprising: a first electrode closest to the plasma source with an aperture through which particles can be extracted to form a beam, the particle source forming a meniscus in the vicinity of the aperture with a substantial electric field at the meniscus; wherein the beam flows through the aperture of a second electrode with an electric field magnitude in the vicinity of the aperture of the second electrode that is substantially greater than the electric field magnitude at the meniscus; and wherein the beam flows through the aperture of a third electrode with an electric field magnitude in the vicinity of the aperture of the third electrode that is substantially smaller than the electric field magnitude at the meniscus. ### Claim 2 (depends on 1) The extractor of claim 1 in which the meniscus and an equipotential surface in the vicinity of the third electrode are substantially concentric and the beam produced is a converging or diverging beam. ### Claim 3 (depends on 1) The extractor of claim 1 in which the meniscus and an equipotential surface in the vicinity of the third electrode are substantially parallel and the beam produced is a parallel beam. ### Claim 4 (depends on 1) The extractor of claim 1, where in the vicinity of the aperture of each of at least two electrodes is a substantially equipotential concentric surface. ### Claim 5 (depends on 1) The extractor of claim 1, wherein the beam flows through the aperture of a fourth electrode. ### Claim 6 (depends on 5) The extractor of claim 5, wherein the beam flows through the aperture of a fifth electrode with an electric field magnitude in the vicinity of the aperture of the fifth electrode that is substantially smaller than the electric field magnitude at the meniscus. ### Claim 7 (depends on 6) The extractor of claim 6, wherein potentials applied to the electrodes are determined from a set of boundary conditions applied at concentric surfaces. ### Claim 8 (depends on 6) The extractor of claim 6, where the electric field magnitude in the vicinity of the fifth electrode is substantially zero. ### Claim 9 (depends on 1) The extractor of claim 1, wherein potentials applied to the electrodes are determined from a set of boundary conditions applied at concentric surfaces. ### Claim 10 (depends on 1) The extractor of claim 1, where the electric field magnitude in the vicinity of the third electrode is substantially zero. ### Claim 11 (depends on 1) The extractor of claim 1 wherein the beam has a brightness of greater than 105 A/sr/m2. ### Claim 12 A low emittance growth extractor for extracting particles from a particle source to form a beam, comprising: a particle source providing a source of particles to form a particle beam; a first region with an entrance for receiving particles from the source, having a high potential and substantial electric field at its entrance, and a low potential with substantially zero electric field at its exit; and a second region with the exit of the first region being the entrance to the second region and with the second region having zero potential and substantially zero electric field at its exit; thereby providing a beam having little or no emittance growth as it traverses the extractor. ### Claim 13 (depends on 12) The extractor of claim 12, wherein the electric field in the first region changes monotonically from a substantial value at its entrance to a much higher value between the entrance and the exit and then to substantially zero at its exit. ### Claim 14 (depends on 12) The extractor of claim 12, wherein the electric field in the second region changes monotonically from substantially zero at its entrance to a substantial value between the entrance and the exit and then to substantially zero at its exit. ### Claim 15 (depends on 14) The extractor of claim 14, wherein the electric field in the first region changes monotonically from a substantial value at its entrance to a much higher value between the entrance and the exit and then to substantially zero at its exit. ### Claim 16 A method of manufacturing a set of electrodes to extract a particle beam from a particle source, comprising: providing a source of particles to form a particle beam; providing a sequence of electrodes that exhibit potentials to produce a beam that flows through the apertures of the electrodes with a substantially zero electric field at an exit aperture of the sequence of electrodes. ### Claim 17 (depends on 16) The method of claim 16, wherein the beam exhibits a potential gradient at a second electrode that is substantially greater than the potential gradient at a first electrode closest to the particle source. ### Claim 18 (depends on 17) The method of claim 17, wherein the beam exhibits a potential gradient at a third electrode that is substantially less than the potential gradient at the first electrode. ### Claim 19 (depends on 18) The method of claim 18, wherein the beam exhibits a non-zero potential gradient at a fourth electrode between the third electrode and a fifth electrode and exhibits a substantially zero potential gradient at the fifth electrode. ### Claim 20 (depends on 16) The method of claim 16, wherein the shapes and potentials applied to the electrodes to produce a beam with a small electric field at the exit aperture are determined from a set of boundary conditions applied at concentric surfaces. ### Claim at position 21 21-29. (canceled)