Single pass lithography overlay technique

摘要

A method and apparatus for measuring the alignment of masks in a photolithographic process. A first grating is formed having lines and spaces on a wafer using a first mask having a pattern for the first grating. A second grating is formed having lines and spaces on the wafer using a second mask having a pattern for the second grating and also the pattern for forming the first grating. A determination is then made based on the difference in the width of either the lines or the spaces of the first and second gratings formed on the wafer if the first and second masks are misaligned.