Composite dielectric with improved etch selectivity for high voltage MEMS structures

摘要

A method of manufacturing MEMS structures and devices that allows the fabrication of dielectric structures with improved etch selectivity and good electrical leakage characteristics. The dielectric structure includes a composite stack of silicon nitride sub-layers with a silicon-rich nitride sub-layer and a stoichiometric silicon nitride sub-layer at opposite ends of the stack. Alternatively, the dielectric structure includes a single silicon nitride layer providing a graded change in silicon content through the dielectric layer, from silicon-rich nitride to stoichiometric silicon nitride.