Method and apparatus for measuring the relative position of a first and a second alignment mark

摘要

The invention relates to a method for measuring the relative position of a first and a second alignment mark on a substrate. The first alignment mark comprises a periodic structure having a first portion with a first periodicity (PE₁) and an adjacent second portion with a second periodicity (PE₂). The second alignment mark (11) comprises a periodic structure having a first portion with the second periodicity (PE₂) and an adjacent second portion with the first periodicity (PE₁). The first and second alignment marks are arranged such that the first portions are substantially located one over the other and the second portions are substantially located one over the other. The method further comprises generating a Moiré pattern from the alignment marks and determining the relative positions of the first and second alignment marks based on the periodicity of the Moiré pattern.