Innovative process development for a new micro-tribosensor using surface micromachining

We present a study on thick Si-rich nitride/polycrystalline Si/silicon oxide multilayer-stacks made by LPCVD and PECVD techniques. The pattern transfer into the multilayer- stacks is achieved by dry etching techniques such as SF6-based ICP plasma and the so-called Bosch processes. The steep profiles and high selectivity obtained for the developed processes allow us to design and fabricate complex MEMS devices which consist of multiple sacrificial and multiple locally doped Si or polycrystalline Si layers. A new etch-stop technique has been developed, which allows accurate stopping on any particular layer with the SF6-based ICP plasma etch process. In order to obtain freestanding structures for tribotesting purposes, the residual stress variation of thick undoped silicon oxide layers (obtained by various methods) has been studied for high temperature processing.