# US 10,502,694 B2 · Methods and apparatus for patterned wafer characterization > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,502,694 B2 - Document ID: US10502694B2 - Status: Granted - Kind: B2 - Application number: 14/449,646 - Filed: 2014-08-01 - Published: 2015-02-12 - Granted: 2019-12-10 - Earliest claimed: 2013-08-06 - Assignees: KLA-Tencor Corporation - Applicants: KLA-Tencor Corporation - Inventors: Thaddeus Gerard Dziura; Stilian Ivanov Pandev; Alexander Kuznetsov; Andrei V. Shchegrov - Web page: https://patentgrep.com/patent/US10502694B2 ## CPC - G01N 21/956: Inspecting patterns on the surface of objects {(contactless testing of electronic circuits G01R31/308; testing currency G07D; manufacturing processes per se of semiconductor devices implementing a measuring step H10P74/20)} - G01N 21/9501: {Semiconductor wafers (manufacturing processes per se of semiconductor devices implementing a measuring step H10P74/20)} - G01N 2201/12: Circuits of general importance; Signal processing - 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) ## Abstract Disclosed are apparatus and methods for characterizing a plurality of structures of interest on a semiconductor wafer. A plurality of spectra signals are measured from a particular structure of interest at a plurality of azimuth angles from one or more sensors of a metrology system. A difference spectrum is determined based on the spectra signals obtained for the azimuth angles. A quality indication of the particular structure of interest is determined and reported based on analyzing the difference spectrum. ## Claims ### Claim 1 A method of characterizing a plurality of structures of interest on a semiconductor wafer, the method comprising: measuring a plurality of spectra signals from a particular location of a particular structure at a plurality of azimuth angles from one or more sensors of a metrology system, wherein the particular structure is a grating structure that was formed by a semiconductor manufacturing process; determining a difference amount between the spectra signals obtained for the azimuth angles; if the difference amount is above a predetermined threshold, determining and reporting that the particular structure does not contain a defect; and if the difference amount is equal to or lower than the predetermined threshold or equal to zero, determining and reporting that the particular structure contains a defect, wherein such defect is below a surface of the particular structure. ### Claim 2 (depends on 1) The method of claim 1, wherein determining that the particular structure contains or does not contain a defect is performed without use of a model or extraction of a quantitative feature value from such particular structure. ### Claim 3 (depends on 1) The method of claim 1, wherein the difference amount is an average difference of a plurality of differences between the spectra signals at the azimuth angles over a plurality of wavelengths. ### Claim 4 (depends on 3) The method of claim 3, the method further comprising: determining theoretical or measured difference amounts between spectra signals for the azimuth angles for a nondefective grating structure; and normalizing the average difference by the theoretical or measured difference amounts to determine a defect quantity. ### Claim 5 (depends on 1) The method of claim 1, wherein the difference amount is a highest one of a plurality of differences between the spectra signals at the azimuth angles at a particular one of a plurality of wavelength ranges. ### Claim 6 (depends on 1) The method of claim 1, wherein measuring spectra includes generating a differential model by using two dimensional beam profile reflectometry. ### Claim 7 (depends on 6) The method of claim 6, further comprising determining a differential model between an image and best fit of a radially symmetric image with a residual error and determining whether the difference spectra indicate a film or defective structure based on such differential model. ### Claim 8 (depends on 1) The method of claim 1, wherein the particular structure is selected from a Directed Self Assembly (DSA) structure, under layer non-Directed Self Assembly (non-DSA) structure, or patterned resist structure. ### Claim 9 (depends on 1) The method of claim 1, wherein the defect is a subsurface defect. ### Claim 10 (depends on 9) The method of claim 9, wherein the particular structure is a Directed Self Assembly (DSA) structure, wherein correcting the particular structure and/or correcting the manufacturing process comprises correcting a chemoepitaxy of the DSA structure. ### Claim 11 (depends on 9) The method of claim 9, wherein the particular structure is a Directed Self Assembly (DSA) structure, wherein correcting the particular structure and/or correcting the manufacturing process comprises correcting a photolithography process' exposure and/or dose for forming the DSA structure. ### Claim 12 A method of characterizing a plurality of structures of interest on a semiconductor wafer, the method comprising: measuring a plurality of spectra signals from a particular structure of interest at a plurality of azimuth angles from one or more sensors of a metrology system; determining a difference spectrum based on the spectra signals obtained for the azimuth angles; determining and reporting a quality indication of the particular structure of interest based on analyzing the difference spectrum; collecting reference data that quantifies pattern defects using a CD SEM tool; obtaining spectra signals at the azimuth angles from a training set of pattern structures having known pattern defects; determining a first relation function between spectra signals measured at different azimuth angles and a residual error, wherein the first relationship is based on the spectra signals obtained at the azimuth angles from the training set; determining a second relation function between a residual error and a quantification of pattern defects based on the reference data; and inputting the spectra signals measured from the particular structure of interest at the azimuth angles into the second relation function to determine a quantification of pattern defects for such particular structure. ### Claim 13 (depends on 12) The method of claim 12, wherein the first and second relation functions are based on a data reduction technique applied to the spectra signals and residual errors for the training set and the particular structure. ### Claim 14 A semiconductor metrology system, comprising: an illuminator for generating illumination; illumination optics for directing the illumination towards a particular location of a particular structure at a plurality of azimuth angles, wherein the particular structure is a grating structure that was formed by a semiconductor manufacturing process; collection optics for directing a plurality of spectra signals in response to the illumination at the azimuth angles from the particular structure to a sensor; the sensor for acquiring the plurality of spectra signals from the particular structure for the azimuth angles; and a processor and memory configured for performing the following operations: determining a difference amount between the spectra signals obtained for the azimuth angles; if the difference amount is above a predetermined threshold, determining and reporting that the particular structure does not contain a defect; and if the difference amount is equal to or lower than the predetermined threshold or equal to zero, determining and reporting that the particular structure contains a defect, wherein such defect is below a surface of the particular structure. ### Claim 15 (depends on 14) The system of claim 14, wherein determining that the particular structure contains or does not contain a defect is performed without use of a model or extraction of a quantitative feature value from such particular structure. ### Claim 16 (depends on 14) The system of claim 14, wherein the difference amount is an average difference of a plurality of differences between the spectra signals at the azimuth angles over a plurality of wavelengths. ### Claim 17 (depends on 16) The system of claim 16, the processor and memory being configured for: determining theoretical or measured difference amounts between spectra signals for the azimuth angles for a nondefective grating structure; and normalizing the average difference by the theoretical or measured difference amounts to determine a defect quantity. ### Claim 18 (depends on 14) The system of claim 14, wherein the difference amount is a highest one of a plurality of differences between the spectra signals at the azimuth angles at a particular one of a plurality of wavelength ranges. ### Claim 19 (depends on 14) The system of claim 14, wherein measuring spectra includes generating a differential model by using two dimensional beam profile reflectometry. ### Claim 20 (depends on 19) The system of claim 19, the processor and memory being configured for determining a difference between the differential model between an image and best fit of a radially symmetric image. ### Claim 21 (depends on 14) The system of claim 14, wherein the particular structure is selected from a Directed Self Assembly (DSA) structure, under layer non-Directed Self Assembly (non-DSA) structure, or patterned resist structure. ### Claim 22 (depends on 14) The system of claim 14, the processor and memory being configured for: collecting reference data that quantifies pattern defects using a CD SEM tool; obtaining spectra signals at the azimuth angles from a training set of pattern structures having known pattern defects; determining a first relation function between spectra signals measured at different azimuth angles and a residual error, wherein the first relationship is based on the spectra signals obtained at the azimuth angles from the training set; determining a second relation function between a residual error and a quantification of pattern defects based on the reference data; and inputting the spectra signals measured from the particular structure at the azimuth angles into the second relation function to determine a quantification of pattern defects for such particular structure. ### Claim 23 (depends on 22) The system of claim 22, wherein the first and second relation functions are based on a data reduction technique applied to the spectra signals and residual errors for the training set and the particular structure. ### Claim 24 (depends on 14) The system of claim 14, wherein the defect is a subsurface defect. ### Claim 25 (depends on 24) The system of claim 24, wherein the particular structure is a Directed Self Assembly (DSA) structure, wherein correcting the particular structure and/or correcting the manufacturing process comprises correcting a chemoepitaxy of the DSA structure. ### Claim 26 (depends on 24) The system of claim 24, wherein the particular structure is a Directed Self Assembly (DSA) structure, wherein correcting the particular structure and/or correcting the manufacturing process comprises correcting a photolithography process' exposure and/or dose for forming the DSA structure. ### Claim 27 A method of characterizing a film of interest on a semiconductor wafer, the method comprising: at one or more sensors of a metrology system, measuring a plurality of spectra signals from a plurality of neighboring locations at a measurement site of the film or a structure that is designed to be uniform across the measurement site; determining an average or mean signal of the spectra signals; determining a standard deviation of each of the spectra signals at each location from the average or mean signal; if one or more of the standard deviations of the spectra signals is above a predetermined threshold from the average or mean, determining and reporting that the film or structure contains a defect; and if one or more of the standard deviations of the spectra signals is equal to or lower than the predetermined threshold or equal to zero, determining and reporting that the film or structure does not contain a defect.