Patent ID: 6947119
Filing Date: 2005-09-20
Classification: G03F

Abstract:
1. A distortion measurement method comprising: a first formation step of repeating, m×n times, shot exposure of arranging first marks on a photosensitive substrate via a reticle and a projection optical system in M rows and N columns at a predetermined column interval and a predetermined row interval, thereby forming first marks in M×m rows and N×n columns on the photosensitive substrate, M and m being natural numbers which are relatively prime, N and n being natural numbers which are relatively prime, and M>m and N>n; a second formation step of repeating, M×N times, shot exposure of arranging second marks on the photosensitive substrate via the reticle in m rows and n columns at the predetermined column interval and the predetermined row interval, thereby forming second marks in M×m rows and N×n columns on the photosensitive substrate, the first and second marks formed in the first and second formation steps forming M×m×N×n over ay marks; a measurement step of measuring misalignment amounts of the first and second marks for each of the M×m×N×n overlay marks; and a calculation step of calculating a distortion amount of the projection optical system on the basis of the misalignment amounts measured in the measurement step.