MARKER STRUCTURE FOR ALIGNMENT OR OVERLAY TO CORRECT PATTERN INDUCED DISPLACEMENT, MASK PATTERN TO DEFINE THE MARKER STRUCTURE, AND LITHOGRAPHIC PROJECTING APPARATUS USING THE MASK PATTERN

摘要

PROBLEM TO BE SOLVED: To provide a mask pattern for imaging a marker structure which decreases lens aberration and influences of the limitation of projection in a lithographic process.

SOLUTION: The mask pattern is formed to image a marker structure on a substrate by lithographic projection. The marker structure is constituted to determine the optical alignment or overlay in use and has a constituent part defining the marker structure. The constituent part is segmented into a plurality of segmented elements (EL; ML), each segmented element having substantially a size of a device feature. In the mask pattern having a segment shape for each segmented element (EL; ML), the mask pattern for the marker structure includes at least one assist feature (EL_sub) located at a critical part of the segment shape for suppressing optical aberration or optical limitation generated in the lithographic projection at the critical part. At least one assist feature (EL_sub) substantially has a size below the resolution of the lithographic projection.

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