Mechanical Characterization of Thin-Film Multilayer Membranes

Inhalt:
This paper reports on a novel mechanical model of the load-deflection of thin-film membranes with tensile or compressive residual stress under uniform differential pressure. Going beyond previous results, the model takes into account the mechanics of multilayers and elastic supports covering all cases between simply supported and rigidly clamped structures. The deflection profiles of long membranes made of silicon nitride (SiNx) films grown by low-pressure vapor deposition (LPCVD), plasma-enhanced chemical vapor deposition (PECVD) and bilayers of both are measured as a function of the applied pressure, membrane dimensions and thickness of the structural films. Plane-strain moduli Eps of 272.5 and 165.6 GPa are extracted from the experimental data using the model for LPCVD and PECVD films, respectively, with corresponding residual stress values sigma0 of 1110 and –1180 MPa.