# US 7,465,939 B2 · Aberration correction device and method for operating same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,465,939 B2 - Document ID: US7465939B2 - Status: Granted - Kind: B2 - Application number: 11/568,175 - Filed: 2005-06-20 - Published: 2007-07-19 - Granted: 2008-12-16 - Earliest claimed: 2004-06-21 - Assignees: ICT Integrated Circuit Testing Gesellschaft für Halbleiterprüftechnik mbH - Inventors: Juergen Frosien - Web page: https://patentgrep.com/patent/US7465939B2 ## CPC - H01J 37/153: Electron-optical or ion-optical arrangements for the correction of image defects, e.g. stigmators - H01J 49/06: Electron- or ion-optical arrangements - H01J 49/288: {using crossed electric and magnetic fields perpendicular to the beam, e.g. Wien filter} - H01J 2237/057: Energy or mass filtering - H01J 2237/1534: Aberrations - H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H) ## Abstract The present invention provides an aberration correction device. The aberration correction device comprises a Wien filter element, a quadrupole element for compensating a focusing property of the Wien filter element, and at least one multipole element for spherical aberration correction. The Wien filter element and said quadrupole element are adapted to generate, in combination, an astigmatic image. Furthermore, the at least one multipole element is adapted to act essentially in a plane of sagittal or meridional focus of the astigmatic image. Thereby, chromatic aberration is reduced as well as spherical aberration can be corrected. ## Claims ### Claim 1 An aberration correction device, comprising: a Wien filter element; a quadrupole element for compensating a focusing property of said Wien filter element; and at least one multipole element for spherical aberration correction, wherein said Wien filter element and said quadrupole element are adapted to generate, in combination, an astigmatic image and wherein said at least one multipole element is adapted to act essentially in a plane of sagittal or meridional focus of said astigmatic image. ### Claim 2 (depends on 1) The aberration correction device according to claim 1, wherein said at least one multipole element is a 4m-pole element with m≧2. ### Claim 3 (depends on 1) The aberration correction device according to claim 1, wherein said Wien filter element and said quadrupole element are adapted to generate an astigmatic crossover of a charged particle beam in a first plane at the center of the Wien filter element and 2n astigmatic crossovers n≧1, of said charged particle beam in a second plane and positioned symmetrically with respect to said crossover at the center of said Wien filter element. ### Claim 4 (depends on 3) The aberration correction device according to claim 3, wherein said at least one multipole element is adapted to act essentially in a plane perpendicular to said first plane and extending through said astigmatic crossover at the center of said Wien filter element. ### Claim 5 (depends on 3) The aberration correction device according to claim 3, wherein said at least one multipole element is adapted to act essentially in a plane perpendicular to said second plane and extending through a selected one of said 2n astigmatic crossovers. ### Claim 6 (depends on 3) The aberration correction device according to claim 3, further comprising one to 2n additional multipole elements, each being adapted to act in a plane perpendicular to said first or second plane and extending through a selected one of said 2n astigmatic crossovers or said astigmatic crossover at the center of said Wien filter element. ### Claim 7 (depends on 3) The aberration correction device according to claim 3, wherein said first plane and said second plane are substantially perpendicular to each other. ### Claim 8 (depends on 3) The aberration correction device according to claim 3, wherein the first plane is the x-z-plane. ### Claim 9 (depends on 3) The aberration correction device according to claim 3, wherein the second plane is the y-z-plane. ### Claim 10 (depends on 1) The aberration correction device according to claim 1, wherein said at least one multipole element comprises a magnetic multipole element. ### Claim 11 (depends on 1) The aberration correction device according to claim 1, wherein said at least one multipole element comprises an electrostatic multipole element. ### Claim 12 (depends on 1) The aberration correction device according to claim 1, wherein said at least one multipole element comprises a combined electrostatic and magnetic multipole element. ### Claim 13 (depends on 1) The aberration correction device according to claim 1, wherein said at least one multipole element is an octupole. ### Claim 14 (depends on 1) The aberration correction device according to claim 1, wherein said at least one multipole element is integrated into said quadrupole element. ### Claim 15 (depends on 1) The aberration correction device according to claim 1, wherein said aberration correction device comprises a plurality of multipole elements which are aligned along the optical axis. ### Claim 16 (depends on 15) The aberration correction device according to claim 15, further comprising combined Wien filter/quadrupole elements aligned with the optical axis and disposed upstream and downstream said plurality of multipole elements. ### Claim 17 (depends on 16) The aberration correction device according to claim 16, wherein said combined Wien filter/quadrupole elements aligned with the optical axis are interposed between said multipole elements. ### Claim 18 (depends on 1) The aberration correction device according to claim 1, further comprising a first charged particle selection element being positioned upstream said Wien filter element. ### Claim 19 (depends on 18) The aberration correction device according to claim 18, wherein said first charged particle selection element is a charged particle angle dependent selection element. ### Claim 20 (depends on 18) The aberration correction device according to claim 18, further comprising a second charged particle selection element being positioned downstream said Wien filter element. ### Claim 21 (depends on 20) The aberration correction device according to claim 20, wherein said second charged particle selection element is a velocity and angle dependent selection element. ### Claim 22 (depends on 1) The aberration correction device according to claim 1, further comprising a first lens for generating a crossover essentially at the center of said Wien filter element. ### Claim 23 (depends on 22) The aberration correction device according to claim 22, further comprising a second lens downstream said Wien filter element. ### Claim 24 (depends on 23) The aberration correction device according to claim 23, wherein said first lens is a magnification lens and said second lens is a demagnification lens. ### Claim 25 (depends on 23) The aberration correction device according to claim 23, wherein said first and second lenses are immersion lenses, said first lens is adapted for decelerating charged particles before entering said Wien filter element, and said second lens is adapted for accelerating the charged particles after leaving said Wien filter element. ### Claim 26 A charged particle beam device comprising: a source of a beam of charged particles; an aberration correction device comprising: a Wien filter element; a quadrupole element for compensating a focusing property of said Wien filter element; and at least one multipole element for spherical aberration correction, wherein said Wien filter element and said quadrupole element are adapted to generate, in combination, an astigmatic image and wherein said at least one multipole element is adapted to act essentially in a plane of sagittal or meridional focus of said astigmatic image; and an objective lens for focusing said beam of charged particles on a surface of a specimen to be inspected. ### Claim 27 A method of operating a charged particle device comprising: producing a substantially stigmatic beam of charged particles; providing an aberration correction device, comprising: a Wien filter element; a quadrupole element for compensating a focusing property of said Wien filter element; and at least one multipole element for spherical aberration correction, wherein said Wien filter element and said quadrupole element are adapted to generate, in combination, an astigmatic image and wherein said at least one multipole element is adapted to act essentially in a plane of sagittal or meridional focus of said astigmatic image; controlling said Wien filter element and said quadrupole element so that their combined action generates an astigmatic image of the beam; and controlling said at least one multipole element so that a spherical aberration in a plane perpendicular to the plane of a crossover associated with said at least one multipole element is corrected. ### Claim 28 (depends on 27) The method according to claim 27, further comprising controlling a plurality of multipole elements to correct a spherical aberration in a respective plane perpendicular to a plane of a respective crossover associated with a respective one of said multipole elements. ### Claim 29 (depends on 27) The method according to claim 27, further comprising selecting charged particles with a charged particle selection element. ### Claim 30 (depends on 27) The method according to claim 27, further comprising focusing the beam of charged particles by means of a first lens so that a crossover is generated essentially at the center of the Wien filter element. ### Claim 31 (depends on 30) The method according to claim 30, further comprising shaping said beam of charged particles by a second lens downstream said Wien filter element. ### Claim 32 (depends on 31) The method according to claim 31, wherein a crossover between said second lens and an objective lens is generated.