A SUBSTRATE, A METHOD OF MEASURING A PROPERTY, AN INSPECTION APPARATUS AND A LITHOGRAPHIC APPARATUS

摘要

Scatterometry for measuring overlay. A second set of superimposed gratings are superposed over a first set of superimposed gratings. The second set of gratings have a different periodicity from the first set of gratings or a different orientation. Consequently the first order diffraction pattern from the second set of superimposed gratings can be distinguished from the first order diffraction pattern from the first set of superimposed gratings.