A METHOD OF DETERMINING FOCUS CORRECTIONS, LITHOGRAPHIC PROCESSING CELL AND DEVICE MANUFACTURING METHOD

摘要

Disclosed is 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 said interfield focus variation information.