Semiconductor structure and method for determining critical dimensions and overlay error

摘要

A semiconductor structure and a method of determining an overlay error produced during formation of a semiconductor structure is disclosed. The semiconductor structure comprises a first periodic pattern and a second periodic pattern, which overlap with each other, wherein a relative position between the overlapping first and second periodic patterns contains information on the magnitude and the sign of an overlay error in a predefined direction that has been caused during the formation of the first and second periodic patterns. The overlay error is determined by directing a light beam of known optical properties onto the first and second periodic patterns and by analyzing the diffracted beam by comparison with reference data. By providing two differently oriented diffracting areas, each comprising first and second periodic patterns, the overlay error in two dimensions can be determined.