# US 11,079,220 B1 · Calibration of azimuth angle for optical metrology stage using grating-coupled surface plasmon resonance > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,079,220 B1 - Document ID: US11079220B1 - Status: Granted - Kind: B1 - Application number: 17/018,726 - Filed: 2020-09-11 - Granted: 2021-08-03 - Earliest claimed: 2020-09-11 - Assignees: Onto Innovation Inc. - Applicants: Onto Innovation Inc. - Inventors: Nicholas James Keller - Web page: https://patentgrep.com/patent/US11079220B1 ## CPC - G01B 11/26: for measuring angles or tapers; for testing the alignment of axes - G01B 11/272: {using photoelectric detection means} - G01B 21/042: {Calibration or calibration artifacts (G01B3/30, G01B9/02072 take precedence)} - G01N 21/17: Systems in which incident light is modified in accordance with the properties of the material investigated (where the material investigated is optically excited causing a change in wavelength of the incident light G01N21/63) - G01N 21/211: {Ellipsometry (optical thickness measurement G01B11/06)} - G01N 21/47: Scattering, i.e. diffuse reflection (G01N21/25, G01N21/41 take precedence {G01N21/55 takes precedence}) - G01N 21/4788: {Diffraction (for sizing particles G01N15/0205)} - G01N 21/55: Specular reflectivity - G01N 21/553: {and using surface plasmons (fluorescence excitation G01N21/648; enhanced Raman G01N21/658)} - G03F 7/70608: {Monitoring the unpatterned workpiece, e.g. measuring thickness, reflectivity or effects of immersion liquid on resist} - G01B 11/0625: {with measurement of absorption or reflection} - G01B 11/0641: {with measurement of polarization} - G01B 2210/56: Measuring geometric parameters of semiconductor structures, e.g. profile, critical dimensions or trench depth - G01N 2021/213: {Spectrometric ellipsometry} - G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS - 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) - 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 Grating-coupled surface plasmon resonance response of a calibration grating is used to calibrate the azimuth angle offset between a sample on the stage and the plane of incidence (POI) of the optical system of an optical metrology device. The calibration grating is configured to produce grating-coupled surface plasmon resonance in response to the optical characteristics of the optical metrology device. The calibration grating is coupled to the stage and positioned at a known azimuth angle with respect to the optical channel of the optical metrology device while the grating-coupled surface plasmon resonance response of the calibration grating is measured. The azimuth angle between an orientation of the calibration grating and the POI of the optical system is determined based on the grating-coupled surface plasmon resonance response. The determined azimuth angle may then be used to correct for an azimuth angle offset between the sample and the POI. ## Claims ### Claim 1 An optical metrology device comprising: an optical system configured to produce a beam of light along a plane of incidence (POI), the beam of light comprising one or more wavelengths; a stage configured to hold a sample and coupled to a calibration grating, the calibration grating configured to produce grating-coupled surface plasmon resonance at the one or more wavelengths of the beam of light; a detector configured to detect and generate signals in response to the beam of light interacting with the calibration grating; and at least one processor coupled to receive the signals from the detector, wherein the at least one processor is configured to: measure the grating-coupled surface plasmon resonance produced by the calibration grating; determine an azimuth angle between an orientation of the calibration grating and the POI of the optical system based on the grating-coupled surface plasmon resonance produced by the calibration grating; and correct for an azimuth angle offset between the sample on the stage and the POI of the optical system using the determined azimuth angle between the orientation of the calibration grating and the POI of the optical system. ### Claim 2 (depends on 1) The optical metrology device of claim 1, wherein the calibration grating comprises a metallic grating. ### Claim 3 (depends on 2) The optical metrology device of claim 2, wherein the metallic grating comprises one or more of copper, gold, silver, aluminum, tungsten, and a doped semiconductor. ### Claim 4 (depends on 1) The optical metrology device of claim 1, wherein the one or more wavelengths is in one or more of a visible wavelength range and an infrared wavelength range. ### Claim 5 (depends on 1) The optical metrology device of claim 1, wherein the at least one processor is configured to determine the azimuth angle based on a plasmon resonance curve that correlates grating-coupled surface plasmon resonance measurements to azimuth angles. ### Claim 6 (depends on 1) The optical metrology device of claim 1, wherein the calibration grating is on the sample. ### Claim 7 (depends on 1) The optical metrology device of claim 1, wherein the calibration grating is on a reference chip attached to the stage. ### Claim 8 (depends on 1) The optical metrology device of claim 1, wherein the at least one processor is configured to correct for the azimuth angle offset between the sample and the POI of the optical system by being configured to alter an orientation of the stage with respect to the POI of the optical system based on the determined azimuth angle or to account for the azimuth angle offset during processing of measurement of the sample. ### Claim 9 (depends on 1) The optical metrology device of claim 1, wherein the optical metrology device is one of a member of a group comprising an ellipsometer, a spectroscopic ellipsometer, a scatterometer, a polarimeter, and a reflectometer. ### Claim 10 A method of calibrating an optical metrology device, comprising: measuring a grating-coupled surface plasmon resonance response of a calibration grating that is coupled to a stage, the grating-coupled surface plasmon resonance response is produced in response to a beam of light from an optical system along a plane of incidence (POI) that is incident on the calibration grating; determining an azimuth angle between an orientation of the calibration grating and the POI of the optical system based on the grating-coupled surface plasmon resonance response of the calibration grating; and correcting for an azimuth angle offset between a sample on the stage and the POI of the optical system using the determined azimuth angle between the orientation of the calibration grating and the POI of the optical system. ### Claim 11 (depends on 10) The method of claim 10, wherein the calibration grating comprises a metallic grating. ### Claim 12 (depends on 11) The method of claim 11, wherein the metallic grating comprises one or more of copper, gold, silver, aluminum, tungsten, and a doped semiconductor. ### Claim 13 (depends on 10) The method of claim 10, wherein determining the azimuth angle is based on a plasmon resonance curve that correlates grating-coupled surface plasmon resonance response to azimuth angles. ### Claim 14 (depends on 10) The method of claim 10, wherein the calibration grating is on the sample. ### Claim 15 (depends on 10) The method of claim 10, wherein the calibration grating is on a reference chip attached to the stage. ### Claim 16 (depends on 10) The method of claim 10, wherein correcting for the azimuth angle offset between the sample and the POI of the optical system comprises one of altering an orientation of the stage with respect to the POI of the optical system based on the determined azimuth angle or accounting for the azimuth angle offset during processing of measurement of the sample. ### Claim 17 (depends on 10) The method of claim 10, wherein the optical metrology device is one of a member of a group comprising an ellipsometer, a spectroscopic ellipsometer, a scatterometer, a polarimeter, and a reflectometer. ### Claim 18 An optical metrology device configured for calibration, comprising: means for producing grating-coupled surface plasmon resonance in response to a beam of light from an optical system along a plane of incidence (POI); means for measuring a grating-coupled surface plasmon resonance response to the beam of light with respect to a stage; means for determining an azimuth angle between the stage and the POI of the optical system based on the grating-coupled surface plasmon resonance response; and means for correcting an azimuth angle offset between a sample on the stage and the POI of the optical system using a determined azimuth angle between the stage and the POI of the optical system. ### Claim 19 (depends on 18) The optical metrology device of claim 18, wherein the means for determining the azimuth angle uses a plasmon resonance curve that correlates grating-coupled surface plasmon resonance response to azimuth angles. ### Claim 20 (depends on 18) The optical metrology device of claim 18, wherein the means for correcting for the azimuth angle offset between the sample on the stage and the POI of the optical system alters an orientation of the stage with respect to the POI of the optical system based on the determined azimuth angle or accounts for the azimuth angle offset during processing of measurement of the sample.