Interferometry system for the mechanical characterization of membranes with silicon oxynitride thin films fabricated by PECVD

摘要

In this paper, we present a method for the internal stress characterisation of silicon membranes with silicon oxynitride thin films (SiO_xN_y) deposited by PECVD (plasma enhanced chemical vacuum deposition). Connecting the interferometric measurements (Twyman-Green interferometer) of out-of-plan displacements of SiO_xN_y-loaded membranes with evaluation of micromechanical parameters (Young's modulus, Poisson ratio) obtained by nanoindentation we evaluated the residual stress of SiO_xN_y thin films via point-wise deflection technique. The magnitude of stress is monitored as a function of the refractive index of SiO_xN_y establishing the relationship between the optical and micromechanical properties of deposited films.