Stress Hysteresis and Mechanical Characterization of Plasma-Enhanced Chemical Vapor Deposited Dielectrics

Abstract

ABSTRACTTwo plasma-enhanced chemical vapor deposited (PECVD) dielectric films pertinent to microelectronic-based applications were examined for thermo-mechanical stability. Both films–silicon nitride and silicon oxy-nitride–showed significant permanent non-equilibrium changes in film stress on thermal cycling and annealing. The linear relationship between stress and temperature changed after the films were annealed at 300°C, representing a structural change in the film resulting in a change in coefficient of thermal expansion and/or biaxial modulus. A double-substrate method was used to deduce both properties before and after the anneal of selected films and the results compared with the modulus deconvoluted from the load-displacement data from small-scale depth-sensing indentation experiments.