# US 2015/0177162 A1 · Angle-Resolved Antisymmetric Scatterometry > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2015/0177162 A1 - Document ID: US20150177162A1 - Status: Published application - Kind: A1 - Application number: 14/500,162 - Filed: 2014-09-29 - Published: 2015-06-25 - Earliest claimed: 2009-07-22 - Assignees: KLA-Tencor Corporation - Applicants: KLA-Tencor Corporation - Inventors: Daniel Kandel; Vladimir Levinski; Noam Sapiens - Web page: https://patentgrep.com/patent/US20150177162A1 ## CPC - G01N 21/95607: {using a comparative method} - G01B 11/14: for measuring distance or clearance between spaced objects or spaced apertures (G01B11/26 takes precedence; rangefinders G01C3/00) - G01B 11/24: for measuring contours or curvatures - G03F 7/70633: {Overlay, i.e. relative alignment between patterns printed by separate exposures in different layers, or in the same layer in multiple exposures or stitching} - G01B 2210/56: Measuring geometric parameters of semiconductor structures, e.g. profile, critical dimensions or trench depth - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS - G03F: PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR; (phototypographic composing devices B41B; photosensitive materials or processes for photographic purposes G03C; electrophotography, sensitive layers or processes therefor G03G) ## Abstract A method for determining an overlay offset may include, but is not limited to: obtaining a first anti-symmetric differential signal (ΔS1) associated with a first scatterometry cell; obtaining a second anti-symmetric differential signal (ΔS2) associated with a second scatterometry cell and computing an overlay offset from the first anti-symmetric differential (ΔS1) signal associated with the first scatterometry cell and the second anti-symmetric differential signal (ΔS2) associated with the second scatterometry cell. ## Claims ### Claim 1 A method for determining an overlay offset comprising: obtaining a first anti-symmetric differential signal associated with a first scatterometry cell; obtaining a second anti-symmetric differential signal associated with a second scatterometry cell; and computing an overlay offset from the first anti-symmetric differential signal associated with the first scatterometry cell and the second anti-symmetric differential signal associated with the second scatterometry cell. ### Claim at position 2 2-9. (canceled) ### Claim 10 (depends on 1) The method of claim 1, further comprising: providing one or more illumination beams from a source. ### Claim 11 (depends on 10) The method of claim 10, wherein the providing one or more illumination beams from a source comprises: providing one or more illumination beams from a source having an at least partially annular illumination pupil. ### Claim 12 (depends on 10) The method of claim 10, wherein the providing one or more illumination beams from a source comprises: providing one or more illumination beams from a source having an at least partially apodized illumination pupil. ### Claim 13 (depends on 10) The method of claim 10, wherein the providing one or more illumination beams from a source comprises: providing a monochromatic illumination beam from a source. ### Claim 14 (depends on 10) The method of claim 10, wherein the providing one or more illumination beams from a source comprises: providing an illumination beam from a source comprising a sequence of wavelengths. ### Claim 15 (depends on 1) The method of claim 1, wherein the first scatterometry cell comprises two-dimensional grating pattern having: a first programmed offset in a first direction; and a second non-zero programmed offset in a second direction orthogonal to the first direction, and wherein the second scatterometry cell comprises a two-dimensional grating pattern having: a first programmed offset in the first direction unequal to the first programmed offset of the first scatterometry cell; and a second non-zero programmed offset in the second direction equal to the second programmed offset of the first scatterometry cell. ### Claim 16 (depends on 1) The method of claim 1, further comprising: receiving one or more scattering signals. ### Claim 17 (depends on 1) The method of claim 1, further comprising: obtaining a third anti-symmetric differential signal associated with a third scatterometry cell. ### Claim 18 (depends on 17) The method of claim 17, further comprising: computing an overlay offset from the second anti-symmetric differential signal associated with the second scatterometry cell and the third anti-symmetric differential signal associated with a third scatterometry cell. ### Claim 19 (depends on 18) The method of claim 18, wherein the computing an overlay offset from the first anti-symmetric differential signal associated with the first scatterometry cell and the second anti-symmetric differential signal associated with the second scatterometry cell comprises: computing an overlay offset in a first direction; and wherein the computing an overlay offset from the second anti-symmetric differential signal associated with the second scatterometry cell and the third anti-symmetric differential signal associated with a third scatterometry cell comprises: computing an overlay offset in a second direction orthogonal to the first direction. ### Claim 20 A system comprising: at least one computing device; and one or more instructions that, when implemented in the computing device, configure the computing device for: obtaining a first anti-symmetric differential signal associated with a first scatterometry cell; obtaining a second anti-symmetric differential signal associated with a second scatterometry cell; and computing an overlay offset from the first anti-symmetric differential signal associated with the first scatterometry cell and the second anti-symmetric differential signal associated with the second scatterometry cell. ### Claim 21 A system comprising: circuitry for obtaining a first anti-symmetric differential signal associated with a first scatterometry cell; circuitry for obtaining a second anti-symmetric differential signal associated with a second scatterometry cell; and circuitry for computing an overlay offset from the first anti-symmetric differential signal associated with the first scatterometry cell and the second anti-symmetric differential signal associated with the second scatterometry cell. ### Claim 22 (depends on 1) The method of claim 1, wherein the obtaining a first anti-symmetric differential signal associated with a first scatterometry cell includes: illuminating the first scatterometry cell via an illumination beam having a first polarization; collecting scattering signals via an analyzer having a second polarization orthogonal to the first polarization; illuminating the first scatterometry cell via an illumination beam having the second polarization; and collecting scattering signals via an analyzer having the first polarization; wherein the obtaining a second anti-symmetric differential signal associated with a second scatterometry cell includes: illuminating the second scatterometry cell via an illumination beam having the first polarization; collecting scattering signals via an analyzer having the second polarization; illuminating the second scatterometry cell via an illumination beam having the second polarization; and collecting scattering signals via an analyzer having the first polarization. ### Claim 23 (depends on 22) The method of claim 22, wherein the first polarization is a first linear polarization; and wherein the second polarization orthogonal to the first polarization is a second linear polarization. ### Claim 24 (depends on 22) The method of claim 22, wherein the first polarization is an azimuthal polarization; and wherein the second polarization orthogonal to the first polarization is a radial polarization. ### Claim 25 (depends on 20) The system of claim 20, wherein the obtaining a first anti-symmetric differential signal associated with a first scatterometry cell includes: illuminating the first scatterometry cell via an illumination beam having a first polarization; collecting scattering signals via an analyzer having a second polarization orthogonal to the first polarization; illuminating the first scatterometry cell via an illumination beam having the second polarization; and collecting scattering signals via an analyzer having the first polarization; wherein the obtaining a second anti-symmetric differential signal associated with a second scatterometry cell includes: illuminating the second scatterometry cell via an illumination beam having the first polarization; collecting scattering signals via an analyzer having the second polarization; illuminating the second scatterometry cell via an illumination beam having the second polarization; and collecting scattering signals via an analyzer having the first polarization. ### Claim 26 (depends on 25) The system of claim 25, wherein the first polarization is a first linear polarization; and wherein the second polarization orthogonal to the first polarization is a second linear polarization. ### Claim 27 (depends on 25) The method of claim 25, wherein the first polarization is an azimuthal polarization; and wherein the second polarization orthogonal to the first polarization is a radial polarization. ### Claim 28 (depends on 21) The system of claim 21, wherein the obtaining a first anti-symmetric differential signal associated with a first scatterometry cell includes: illuminating the first scatterometry cell via an illumination beam having a first polarization; collecting scattering signals via an analyzer having a second polarization orthogonal to the first polarization; illuminating the first scatterometry cell via an illumination beam having the second polarization; and collecting scattering signals via an analyzer having the first polarization; wherein the obtaining a second anti-symmetric differential signal associated with a second scatterometry cell includes: illuminating the second scatterometry cell via an illumination beam having the first polarization; collecting scattering signals via an analyzer having the second polarization; illuminating the second scatterometry cell via an illumination beam having the second polarization; and collecting scattering signals via an analyzer having the first polarization.