# US 8,570,515 B2 · Periodic patterns and technique to control misalignment between two layers > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,570,515 B2 - Document ID: US8570515B2 - Status: Granted - Kind: B2 - Application number: 12/628,092 - Filed: 2009-11-30 - Published: 2010-03-25 - Granted: 2013-10-29 - Earliest claimed: 2001-04-10 - Assignees: KLA-Tencor Corporation - Applicants: Ibrahim Abdulhalim; Mike Adel; Michael Friedmann; Michael Faeyrman - Inventors: Ibrahim Abdulhalim; Mike Adel; Michael Friedmann; Michael Faeyrman - Web page: https://patentgrep.com/patent/US8570515B2 ## CPC - G01B 11/26: for measuring angles or tapers; for testing the alignment of axes - G01B 11/14: for measuring distance or clearance between spaced objects or spaced apertures (G01B11/26 takes precedence; rangefinders G01C3/00) - G01N 21/9501: {Semiconductor wafers (manufacturing processes per se of semiconductor devices implementing a measuring step H10P74/20)} - 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} - H10P 74/203: {Structural properties, e.g. testing or measuring thicknesses, line widths, warpage, bond strengths or physical defects} - H10W 46/00: Marks applied to devices, e.g. for alignment or identification - H10W 46/301: {for alignment} - H10W 46/501: {for use before dicing} - H10W 46/503: {Located in scribe lines} - 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) - H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10 - H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10 ## Abstract A method and system to measure misalignment error between two overlying or interlaced periodic structures are proposed. The overlying or interlaced periodic structures are illuminated by incident radiation, and the diffracted radiation of the incident radiation by the overlying or interlaced periodic structures are detected to provide an output signal. The misalignment between the overlying or interlaced periodic structures may then be determined from the output signal. ## Claims ### Claim 1 A method for detecting misalignment of overlying or interlaced periodic structures having substantially the same pitch, comprising: illuminating the overlying or interlaced periodic structures having substantially the same pitch with incident radiation; detecting diffracted radiation from the illuminated portions of the overlying or interlaced periodic structures along two different detection paths to provide at least one output signal, wherein positive first-order diffraction is directed along one of the two different detection paths and negative first-order diffraction is directed along the other one of the two different detection paths; and determining a misalignment between the structures from the at least one output signal; said determining comprising calculating a derived signal from the at least one output signal, wherein the derived signal contains information related to polarization angle. ### Claim 2 (depends on 1) The method of claim 1, wherein said determining includes comparing the at least one output signal with reference signal. ### Claim 3 (depends on 2) The method of claim 2, wherein the reference signal comprises a database. ### Claim 4 (depends on 1) The method of claim 1, wherein said determining includes subtracting the intensities of the positive first-order diffraction and negative first-order diffraction to obtain a differential intensity value. ### Claim 5 (depends on 1) The method of claim 1, wherein the positive first-order diffraction and negative first-order diffraction are detected substantially simultaneously. ### Claim 6 (depends on 1) The method of claim 1, wherein the positive first-order diffraction and negative first-order diffraction are detected sequentially. ### Claim 7 (depends on 1) The method of claim 1, wherein the positive first-order diffraction and negative first-order diffraction are detected sequentially or substantially simultaneously, and said determining includes subtracting the intensities of the positive first-order diffraction and negative first-order diffraction to obtain a differential intensity value. ### Claim 8 (depends on 7) The method of claim 7, wherein said determining includes comparing the differential intensity value to a database to determine a misalignment between the structures. ### Claim 9 (depends on 1) The method of claim 1, wherein said determining includes obtaining a difference between phase angles of the positive first-order diffraction and negative first-order diffraction. ### Claim 10 (depends on 9) The method of claim 9, wherein said obtaining includes interfering the positive first-order diffraction and negative first-order diffraction to obtain a differential phase value. ### Claim 11 (depends on 10) The method of claim 10, wherein said determining includes comparing the differential phase value to a database to determine a misalignment between the structures. ### Claim 12 (depends on 1) The method of claim 1, wherein the incident polarization angle of an illumination beam used in the illuminating to produce said positive and negative first order diffractions is monitored. ### Claim 13 (depends on 12) The method of claim 12, wherein a differential intensity is calculated from said positive and negative first order diffractions produced at a selected incident polarization angle of said illumination beam. ### Claim 14 (depends on 13) The method of claim 13, wherein the determining determines the misalignment between the structures from said calculated differential intensity. ### Claim 15 (depends on 13) The method of claim 13, wherein the differential intensity is calculated from said positive and negative first order diffractions at an incident polarization angle of said illumination beam where intensities of the first order diffractions are maximum. ### Claim 16 (depends on 1) The method of claim 1, wherein the detecting detects intensities of the positive first-order diffraction and negative first-order diffraction from the illuminated portions of the overlying or interlaced periodic structures at a plurality of different incident polarization angles of an illumination beam used in the illuminating to produce said positive and negative first order diffractions. ### Claim 17 An apparatus for detecting misalignment of overlying or interlaced periodic structures, comprising: a source illuminating the overlying or interlaced periodic structures with incident radiation; at least one detector detecting diffracted radiation from the illuminated portions of the overlying or interlaced periodic structures along two different detection paths to provide at least one output signal, wherein positive first-order diffraction is directed along one of the two different detection paths and negative first-order diffraction is directed along the other one of the two different detection paths; and a processor determining a misalignment between the structures from the at least one output signal, wherein the at least one detector detects intensities of the positive first-order diffraction and negative first-order diffraction from the illuminated portions of the overlying or interlaced periodic structures at a plurality of different incident polarization angles, and said processor subtracts the intensities of the positive first-order diffraction and negative first-order diffraction detected at each of said plurality of different incident polarization angles to obtain a corresponding differential intensity value. ### Claim 18 (depends on 17) The apparatus of claim 17, wherein said processor compares the at least one output signal with a reference signal. ### Claim 19 (depends on 18) The apparatus of claim 18, wherein the reference signal comprises a database. ### Claim 20 (depends on 17) The apparatus of claim 17, wherein said processor calculates a derived signal from the at least one output signal. ### Claim 21 (depends on 17) The apparatus of claim 17, wherein the positive first-order diffraction and negative first-order diffraction are detected substantially simultaneously. ### Claim 22 (depends on 17) The apparatus of claim 17, wherein the positive first-order diffraction and negative first-order diffraction are detected sequentially. ### Claim 23 (depends on 17) The apparatus of claim 17, wherein said processor subtracts the intensities of the positive first-order diffraction and negative first-order diffraction to obtain a differential intensity value. ### Claim 24 (depends on 23) The apparatus of claim 23, wherein said processor compares the differential intensity value to a database to determine a misalignment between the structures. ### Claim 25 (depends on 17) The apparatus of claim 17, wherein said processor compares the differential intensity values obtained at said plurality of different incident polarization angles to a database to determine a misalignment between the structures. ### Claim 26 (depends on 17) The apparatus of claim 17, wherein said processor obtains a difference between phase angles of the positive first-order diffraction and negative first-order diffraction. ### Claim 27 (depends on 17) The apparatus of claim 17, wherein the positive first-order diffraction and negative first-order diffraction interfere to provide a differential phase value. ### Claim 28 (depends on 27) The apparatus of claim 27, wherein said processor compares the differential phase value to a database to determine a misalignment between the structures. ### Claim 29 A method for detecting misalignment of overlying or interlaced periodic structures, comprising: illuminating the overlying or interlaced periodic structures with incident radiation; detecting diffracted radiation from the illuminated portions of the overlying or interlaced periodic structures along two different detection paths to provide at least one output signal, wherein positive first-order diffraction is directed along one of the two different detection paths and negative first-order diffraction is directed along the other one of the two different detection paths; and determining a misalignment between the structures from the at least one output signal wherein the detecting detects intensities of the positive first-order diffraction and negative first-order diffraction from the illuminated portions of the overlying or interlaced periodic structures at a plurality of different incident polarization angles, and said determining includes subtracting the intensities of the positive first-order diffraction and negative first-order diffraction detected at each of said plurality of different incident polarization angles to obtain a corresponding differential intensity value. ### Claim 30 (depends on 29) The method of claim 29, wherein said determining includes comparing the differential intensity values obtained at said plurality of different incident polarization angles to a database to determine a misalignment between the structures. ### Claim 31 A method for detecting misalignment of overlying or interlaced periodic structures, comprising: illuminating the overlying or interlaced periodic structures with incident radiation; detecting diffracted radiation from the illuminated portions of the overlying or interlaced periodic structures along two different detection paths to provide at least one output signal, wherein positive first-order diffraction is directed along one of the two different detection paths and negative first-order diffraction is directed along the other one of the two different detection paths; and determining a misalignment between the structures from the at least one output signal, wherein said determining includes obtaining a difference between polarization angles of the positive first-order diffraction and negative first-order diffraction. ### Claim 32 (depends on 31) The method of claim 31, wherein said determining includes comparing the difference to a database to determine a misalignment between the structures. ### Claim 33 An apparatus for detecting misalignment of overlying or interlaced periodic structures, comprising: a source illuminating the overlying or interlaced periodic structures with incident radiation; at least one detector detecting diffracted radiation from the illuminated portions of the overlying or interlaced periodic structures along two different detection paths to provide at least one output signal, wherein positive first-order diffraction is directed along one of the two different detection paths and negative first-order diffraction is directed along the other one of the two different detection paths; and a processor determining a misalignment between the structures from the at least one output signal, said determining including calculating a derived signal from the at least one output signal, wherein the derived signal contains information related to polarization angle. ### Claim 34 (depends on 33) The apparatus of claim 33, wherein the derived signal contains information related to differential intensity, differential phase, or differential polarization angle. ### Claim 35 (depends on 33) The apparatus of claim 33, further comprising a reference radiation detection unit that detects radiation from the source and provides information regarding intensity fluctuation of the source to the processor. ### Claim 36 (depends on 35) The apparatus of claim 35, said processor normalizing said at least one output signal using said information when it determines a misalignment between the structures from the at least one output signal. ### Claim 37 An apparatus for detecting misalignment of overlying or interlaced periodic structures, comprising: a source illuminating the overlying or interlaced periodic structures with incident radiation; at least one detector detecting diffracted radiation from the illuminated portions of the overlying or interlaced periodic structures along two different detection paths to provide at least one output signal, wherein positive first-order diffraction is directed along one of the two different detection paths and negative first-order diffraction is directed along the other one of the two different detection paths; and a processor determining a misalignment between the structures from the at least one output signal, wherein said processor obtains a difference between polarization angles of the positive first-order diffraction and negative first-order diffraction. ### Claim 38 (depends on 37) The apparatus of claim 37, wherein said processor compares the difference to a database to determine a misalignment between the structures. ### Claim 39 An apparatus for detecting misalignment of overlying or interlaced periodic structures, comprising: a source illuminating the overlying or interlaced periodic structures with incident radiation along an illumination path; a polarizer in said illumination path to polarize the incident radiation before it reaches the overlying or interlaced periodic structures; at least one detector detecting diffracted radiation from the illuminated portions of the overlying or interlaced periodic structures along two different detection paths to provide at least one output signal, wherein positive first-order diffraction is directed along one of the two different detection paths and negative first-order diffraction is directed along the other one of the two different detection paths; and a processor determining a misalignment between the structures from the at least one output signal. ### Claim 40 (depends on 39) The apparatus of claim 39, wherein each of the detection paths includes an analyzer. ### Claim 41 (depends on 40) The apparatus of claim 40, wherein said polarizer is rotated and the analyzers are fixed in positions when the at least one detector is detecting diffracted radiation from the illuminated portions of the overlying or interlaced periodic structures. ### Claim 42 (depends on 40) The apparatus of claim 40, wherein said analyzers are rotated and the polarizer is fixed in position when the at least one detector is detecting diffracted radiation from the illuminated portions of the overlying or interlaced periodic structures. ### Claim 43 (depends on 39) The apparatus of claim 39, wherein the at least one detector detects intensities of the positive first-order diffraction and negative first-order diffraction from the illuminated portions of the overlying or interlaced periodic structures at a plurality of different incident polarization angles, and said processor subtracts the intensities of the positive first-order diffraction and negative first-order diffraction. ### Claim 44 (depends on 39) The apparatus of claim 39, further comprising a reference radiation detection unit that detects radiation from the source and provides information regarding intensity fluctuation of the source to the processor. ### Claim 45 (depends on 44) The apparatus of claim 44, said processor normalizing said at least one output signal using said information. ### Claim 46 A method for detecting misalignment of overlying or interlaced periodic structures, comprising: illuminating the overlying or interlaced periodic structures in an illumination path with incident radiation; detecting diffracted radiation from the illuminated portions of the overlying or interlaced periodic structures along two different detection paths to provide at least one output signal, wherein positive first-order diffraction is directed along one of the two different detection paths and negative first-order diffraction is directed along the other one of the two different detection paths, wherein radiation in the illumination or detection paths is polarized and said illuminating and detecting are performed at different polarization angles to provide a plurality of output signals; and determining a misalignment between the structures from the plurality of output signals. ### Claim 47 (depends on 46) The method of claim 46, wherein said illuminating illuminates by means of a polarized illumination beam at an incident polarization angle. ### Claim 48 (depends on 46) The method of claim 46, further comprising selecting from said different polarization angles a particular polarization angle. ### Claim 49 (depends on 48) The method of claim 48, wherein said determining includes calculating a differential intensity from the output signal provided by said illuminating and detecting when performed at said particular polarization angle. ### Claim 50 (depends on 48) The method of claim 48, wherein the polarization angle at which the intensity of the diffracted radiation from the illuminated portions of the overlying or interlaced periodic structures is a maximum is selected as said particular polarization angle. ### Claim 51 (depends on 46) The method of claim 46, wherein the incident radiation is polarized. ### Claim 52 An apparatus for detecting misalignment of overlying or interlaced periodic structures having substantially the same pitch, comprising: a source illuminating the overlying or interlaced periodic structures having substantially the same pitch in an illumination path with incident radiation; at least one detector detecting diffracted radiation from the illuminated portions of the overlying or interlaced periodic structures along two different detection paths to provide at least one output signal, wherein positive first-order diffraction is directed along one of the two different detection paths and negative first-order diffraction is directed along the other one of the two different detection paths; an instrument causing an alteration of a polarization angle of radiation in the illumination or detection paths so that the at least one detector provides a plurality of output signals corresponding to different polarization angles of radiation in the illumination or detection paths; a processor processing the plurality of output signals provided by said at least one detector to determine a misalignment between the structures. ### Claim 53 (depends on 52) The apparatus of claim 52, wherein said instrument includes a polarizer in the illumination path, and an analyzer in each of the detection paths. ### Claim 54 (depends on 53) The apparatus of claim 53, wherein said instrument includes a device, and said polarizer is rotated by the device and the analyzers are fixed in positions when the at least one detector is detecting diffracted radiation from the illuminated portions of the overlying or interlaced periodic structures. ### Claim 55 (depends on 53) The apparatus of claim 53, wherein said instrument includes a device, and said analyzers are rotated and the polarizer is fixed in position when the at least one detector is detecting diffracted radiation from the illuminated portions of the overlying or interlaced periodic structures. ### Claim 56 (depends on 52) The apparatus of claim 52, wherein the at least one detector detects intensities of the positive first-order diffraction and negative first-order diffraction from the illuminated portions of the overlying or interlaced periodic structures at said plurality of different polarization angles, and said processor subtracts the intensities of the positive first-order diffraction and negative first-order diffraction. ### Claim 57 An apparatus for detecting misalignment of overlying or interlaced periodic structures, comprising: a source illuminating the overlying or interlaced periodic structures with incident radiation; at least one detector detecting diffracted radiation from the illuminated portions of the overlying or interlaced periodic structures along two different detection paths to provide output signals, wherein positive first-order diffraction is directed along one of the two different detection paths and negative first-order diffraction is directed along the other one of the two different detection paths; and a processor calculating a derived signal from the output signals and determining a misalignment between the structures from said derived signal, said derived signal containing information related to polarization of the output signals. ### Claim 58 (depends on 57) The apparatus of claim 57, wherein the derived signal contains information related to polarization angle. ### Claim 59 A method for detecting misalignment of overlying or interlaced periodic structures having substantially the same pitch, comprising: illuminating the overlying or interlaced periodic structures with incident polarized radiation; detecting diffracted radiation from the illuminated portions of the overlying or interlaced periodic structures along two different detection paths to provide output signals, wherein positive first-order diffraction is directed along one of the two different detection paths and negative first-order diffraction is directed along the other one of the two different detection paths; and calculating a derived signal from the output signals and determining a misalignment between the structures from said derived signal, said derived signal containing information related to polarization of the output signals. ### Claim 60 (depends on 59) The method of claim 59, wherein the derived signal contains information related to polarization angle. ### Claim 61 A method for detecting misalignment of overlying or interlaced periodic structures having substantially the same pitch, comprising: illuminating the overlying or interlaced periodic structures having substantially the same pitch with incident radiation; detecting diffracted radiation from the illuminated portions of the overlying or interlaced periodic structures along two different detection paths to provide at least one output signal, wherein positive first-order diffraction is directed along one of the two different detection paths and negative first-order diffraction is directed along the other one of the two different detection paths; and determining a misalignment between the structures from the at least one output signal, said determining including calculating a derived signal from the at least one output signal, wherein the derived signal contains information related to differential polarization angle.