Impact of thermal treatment on the residual stress and Young's modulus of thin a-SiC:H membranes applying bulge testing

摘要

Silicon carbide (SiC) as a wide bandgap semiconductor features outstanding electrical and mechanical properties as well as enhanced inertness against a large variety of chemical substances and a high temperature stability. Therefore, it is the material of choice for high performance microelectromechanical systems. This study presents the impact of thermal treatment on a 500 nm thin hydrogenated amorphous SiC membrane. Layers were synthesized using an inductively-coupled plasma-enhanced chemical vapour deposition equipment and processed to obtain circular diaphragms. Bulge testing is performed with a uniformly applied pressure load and the bending characteristics as well as the flexural Young's modulus and residual tensile stress are determined. With increasing annealing temperature a massive increase of membrane stress and only a slight increase of Young's modulus occurs while the bending characteristic of the diaphragm is a nearly perfect membrane type independent of thermal loading.