Primary study on ellipsometry of large roughness surface

Based on the method of space filtering, a subassembly of space filter consisting of lens and filter is introduced and a conventional null ellipsometer has been improved to measure large roughness surface and film with large roughness interface. From theory, the possibility of using space filter in null ellipsometer to get ellipsometric parameters of large roughness surfaces corresponding to the smooth surface is analyzed, and primary experiment is carried out. Experiment results show that the improved null ellipsometer can obtain preferable repeatability and accuracy of optical parameters of large roughness surface and film with large roughness interface.