A detailed experimental and analytical study of the thermal expansion of dielectric thin films on Si by x-ray reflectivity

Abstract

We present a method of using x-ray reflectivity to measure the thermal expansion coefficient for submicron dielectric thin films. Technique criteria are discussed including importance of thickness accuracy, thickness boundaries, and detecting thickness changes due to irreversible phenomena. The thin film mechanics required to extract the thermal expansion parameter for a freestanding film as opposed to an attached film are discussed. Thermal expansion measurements on silicon carbide and silicon nitride thin films using this method agree with literature values obtained for bulk samples. The thermal expansion of several carbon-doped silicon oxide thin films was also measured.