Accurate determination of film thickness by low-angle X-ray reflectionProject supported by the the Foundation for Key Research Programs of the China 9th 5-year Plan, from Chinese Academy of Sciences (Grant No. KJ951-AL-401) and the National Natural Science Foundation of China (Grant No. 19890310).

Abstract

A modified Bragg law for straightforward determining the film thickness by low-angle X-ray reflection was derived based on the geometrical optical theory. We showed that this modified Bragg law and its inference formulae could be used to accurately determine the thickness of the monolayer or multilayer film. Furthermore, the modified Bragg law for determining the superlattice period presented earlier by others can be derived from the above modified Bragg law. The similar inference formulae were also given. The precision in determining the film thickness and/or superlattice period by the above formulae was discussed.