# US 2015/0177166 A1 · Inspection Method and Apparatus, Lithographic System and Device Manufacturing Method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2015/0177166 A1 - Document ID: US20150177166A1 - Status: Published application - Kind: A1 - Application number: 14/416,484 - Filed: 2013-06-18 - Published: 2015-06-25 - Earliest claimed: 2012-07-23 - Assignees: ASML Netherlands B.V. - Applicants: ASML Netherlands B.V. - Inventors: Hugo Augustinus Joseph Cramer; Robert John Socha; Patricius Aloysius Jacobus Tinnemans; Jean-Pierre Agnes Henricus Marie Vaessen - Web page: https://patentgrep.com/patent/US20150177166A1 ## CPC - G01N 23/203: Measuring back scattering - G03F 7/70058: {Mask illumination systems} - G03F 7/70625: {Dimensions, e.g. line width, critical dimension [CD], profile, sidewall angle or edge roughness} - H01J 37/26: Electron or ion microscopes; Electron or ion diffraction tubes - 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) - H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H) ## Abstract An inspection method determines values of profile parameters of substrate patterns. A baseline substrate with a baseline pattern target (BP) is produced that has a profile described by profile parameters, for example CD (median critical dimension), SWA (side wall angle) and RH (resist height). Scatterometry is used to obtain first and second signals from first and second targets. Values of differential pattern profile parameters are calculated using a Bayesian differential cost function based on a difference between the baseline pupil and the perturbed pupil and dependence of the pupil on pattern profile parameters. For example, the difference is measured between a baseline process and a perturbed process for stability control of a lithographic process. Fed-forward differential stack parameters are also calculated from observations of stack targets on the same substrates as the pattern targets. ## Claims ### Claim 1 An inspection method for determining values of profile parameters of patterns formed on substrates, the method comprising: supporting a first substrate comprising a first pattern target; illuminating the first pattern target with radiation and detecting scattered radiation to obtain a first pattern signal; supporting a second substrate comprising a second pattern target; illuminating the second pattern target with radiation and detecting scattered radiation to obtain a second pattern signal; and calculating values of differential pattern profile parameters using a difference between the first pattern signal and the second pattern signal. ### Claim 2 (depends on 1) The method of claim 1, wherein the calculating comprises calculating values of differential pattern profile parameters using a regularized cost function. ### Claim 3 (depends on 2) The method of claim 2, wherein said cost function is a Bayesian differential cost function. ### Claim 4 (depends on 1) The method of claim 1, wherein the calculating comprises further using predetermined information as to the dependence of a pattern signal on a pattern profile parameter. ### Claim 5 (depends on 1) The method of claim 1, wherein the first substrate is the same as the second substrate. ### Claim 6 (depends on 1) The method of claim 1, wherein the calculating comprises using information as to a difference introduced between the first and second pattern targets when they were formed. ### Claim 7 (depends on 1) The method of claim 1, wherein the first substrate further comprises a first stack target, and the second substrate further comprises a second stack target, and the method further comprises: illuminating the first stack target with radiation and detecting scattered radiation to obtain a first stack signal; and illuminating the second stack target with radiation and detecting scattered radiation to obtain a second stack signal, wherein the calculating comprises using a difference between the first stack signal and the second stack signal, thereby to reduce the influence of variations between stacks underlying the pattern targets. ### Claim 8 (depends on 7) The method of claim 7 wherein the calculating further comprises: calculating values of differential stack parameters using the difference between the first stack signal and the second stack signal and predetermined information as to the dependence of a stack signal on stack parameters; and using the calculated values of differential stack parameters, in calculating values of differential pattern profile parameters. ### Claim 9 (depends on 8) The method of claim 8, wherein the calculating values of differential stack parameters uses a Bayesian differential cost function. ### Claim 10 (depends on 8) The method of claim 8, wherein the calculated values of differential stack parameters are kept constant when calculating values of differential pattern profile parameters. ### Claim 11 An inspection apparatus for determining values of profile parameters of substrate patterns, the inspection apparatus comprising: a support for a substrate; an optical system configured to illuminate one or more pattern targets on the substrate with radiation and detect scattered radiation to obtain a corresponding pattern signal; and a processor configured to calculate values of differential pattern profile parameters using a difference between a first pattern signal detected from a first pattern target using the optical system and a second pattern signal detected from a second pattern target using the optical system. ### Claim 12 (depends on 11) The apparatus of claim 11, wherein said processor is configured further to use in said calculation, predetermined information as to the dependence of a pattern signal on a pattern profile parameter. ### Claim 13 (depends on 11) The apparatus of claim 11, wherein said processor is configured further to use in said calculation, information as to a difference introduced between the first and second pattern targets when they were formed. ### Claim 14 (depends on 11) The apparatus of claim 11 wherein said optical system is further configured to illuminate a first stack target with radiation and detect scattered radiation to obtain a first stack signal and to illuminate a second stack target with radiation and detect scattered radiation to obtain a second stack signal, and wherein said processor is further configured to use in said calculation, a difference between the first stack signal and the second stack signal, thereby to reduce the influence of variations between stacks underlying the pattern targets. ### Claim 15 (depends on 14) The apparatus of claim 14, wherein the processor is configured to calculate values of differential stack parameters using the difference between the first stack signal and the second stack signal and predetermined information as to the dependence of a stack signal on stack parameters and is further configured to use the calculated values of differential stack parameters, in calculating values of differential pattern profile parameters. ### Claim 16 A computer program product comprising machine-readable instructions for causing a processor to perform operations comprising: obtaining a first patterned signal corresponding to detected scattered radiation from a first pattern target on a first substrate; obtaining a second patterned signal corresponding to detected scattered radiation from a second pattern target on a second substrate; and calculating values of differential pattern profile parameters using a difference between the first pattern signal and the second pattern signal. ### Claim 17 A lithographic system comprising: a lithographic apparatus comprising: an illumination optical system configured to illuminate a pattern; a projection optical system configured to project an image of the pattern onto a substrate; and an inspection apparatus, comprising: a support for the substrate; an optical system configured to illuminate one or more pattern targets on the substrate with radiation and detect scattered radiation to obtain a corresponding pattern signal; and a processor configured to calculate values of differential pattern profile parameters using a difference between a first pattern signal detected from a first pattern target using the optical system and a second pattern signal detected from a second pattern target using the optical system, wherein the lithographic apparatus is configured to use the measurement results from the inspection apparatus in applying the pattern to further substrates. ### Claim 18 (canceled) ### Claim 19 A computer-readable storage device having computer-executable instructions stored thereon, execution of which, by a computing device, causes the computing device to perform operations comprising: obtaining a first patterned signal corresponding to detected scattered radiation from a first pattern target on a first substrate; obtaining a second patterned signal corresponding to detected scattered radiation from a second pattern target on a second substrate; and calculating values of differential pattern profile parameters using a difference between the first pattern signal and the second pattern signal. ### Claim 20 A lithographic system comprising: a lithographic apparatus comprising: an illumination optical system arranged to illuminate a pattern; a projection optical system arranged to project an image of the pattern onto a substrate; and an inspection apparatus comprising: a support for a substrate; an optical system configured to illuminate one or more pattern targets on the substrate with radiation and to detect scattered radiation to obtain a corresponding pattern signal; and a processor arranged to calculate values of differential pattern profile parameters using a difference between a first pattern signal detected from a first pattern target using the optical system and a second pattern signal detected from a second pattern target using the optical system, wherein the lithographic apparatus is configured to use the measurement results from the inspection apparatus in applying the pattern to further substrates. ### Claim 21 A method of manufacturing devices wherein a device pattern is applied to a series of substrates using a lithographic process, the method comprising: inspecting at least one periodic structure formed as part of or beside, the device pattern on at least one of the substrates using a method comprising: supporting a first substrate comprising a first pattern target; illuminating the first pattern target with radiation and detecting scattered radiation to obtain a first pattern signal; supporting a second substrate comprising a second pattern target; illuminating the second pattern target with radiation and detecting scattered radiation to obtain a second pattern signal; and calculating values of differential pattern profile parameters using a difference between the first pattern signal and the second pattern signal; and controlling the lithographic process for later substrates in accordance with the result of the inspecting method.