Method of Determining Focus Corrections, Lithographic Processing Cell and Device Manufacturing Method
AssigneeASML Netherlands B.V.
InventorsArend Johannes KISTEMAN, Wim Tjibbo TEL, Thomas THEEUWES, Antoine Gaston Marie KIERS
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Abstract
A method of, and associated apparatus for, determining focus corrections for a lithographic projection apparatus. The method comprises exposing a plurality of global correction fields on a test substrate, each comprising a plurality of global correction marks, and each being exposed with a tilted focus offset across it; measuring a focus dependent characteristic for each of the plurality of global correction marks to determine interfield focus variation information; and calculating interfield focus corrections from the interfield focus variation information.
Claims9
A method of determining focus corrections for a lithographic projection apparatus, the method comprising:
- measuring a focus dependent characteristic for each of a plurality of intrafield correction marks on a test substrate, wherein the intrafield correction marks are arranged in a plurality of intrafield correction fields, the intrafield correction marks having been exposed using varying focus;
- determining intrafield focus variation information for each intrafield correction mark location from the measured focus dependent characteristic;
- and
- calculating the intrafield focus corrections from the intrafield focus variation information;
- wherein the calculating intrafield focus corrections comprises taking into account scan-up-scan-down effects, whereby measured parameters show variation in dependence of the scanning direction during a lithographic process.
A lithocell for determining focus corrections for use in a lithographic projection process, the apparatus comprising:
- a lithographic apparatus configured to expose a plurality of intrafield correction marks on a test substrate, the intrafield correction marks are arranged in a plurality of intrafield correction fields, the intrafield correction marks having been exposed with a pseudo-randomized focus and dose settings per field;
- an inspection apparatus configured to measure a focus dependent characteristic for each of the plurality of intrafield correction marks;
- and
- a processor configured to determine intrafield focus variation information for each intrafield correction mark location from the measured focus dependent characteristic, and to calculate intrafield focus corrections from the intrafield focus variation information;
- wherein the calculating intrafield focus corrections comprises taking into account scan-up-scan-down effects, whereby measured parameters show variation in dependence of the scanning direction during a lithographic process.
A tangible computer readable storage medium having program instructions stored thereon, execution of which by at least one processor cause the at least one processor to perform operations comprising:
- measuring a focus dependent characteristic for each of a plurality of intrafield correction marks on a test substrate, wherein the intrafield correction marks are arranged in a plurality of intrafield correction fields, the intrafield correction marks having been exposed using varying focus;
- determining intrafield focus variation information for each intrafield correction mark location from the measured focus dependent characteristic;
- and
- calculating the intrafield focus corrections from the intrafield focus variation information;
- wherein the calculating intrafield focus corrections comprises taking into account scan-up-scan-down effects, whereby measured parameters show variation in dependence of the scanning direction during a lithographic process.
Dependencies are inferred from the claim text.