Method for determining structure characteristic and metrology apparatus

摘要

A method and apparatus for determining the characteristics of the structure are disclosed.In one arrangement, the first scattered radiation is generated by illuminating the structure using the first illumination radiation.A first interference pattern is formed by part of the first scattered radiation reaching the sensor and interference between the first reference radiation.The structure is also illuminated from a different direction using a second illumination radiation.The second reference radiation is used to form a second interference pattern.The first interference pattern and the second interference pattern are used to determine the structural characteristics.The first reference radiation on the sensor and the azimuth of the second reference radiation are different.Diagram