A dry single step process for the manufacture of released MEMS structures

This paper describes a novel method of producing released MEMS structures, that eliminates the requirement for a second processing step usually requiring hydroflouric acid (often considered undesirable and potentially dangerous) to release the structure etched on silicon on insulator wafers. The new method utilizes a standard STS Deep reactive ion ether and silicon on insulator type wafers, as does the usual two-step processing route, however rather than trying to eliminate the 'notching' phenomena experienced when the plasma reaches the buried oxide layer it has been exploited to release the structure. This paper details how the notching effect has been exploited and characterized for a number of feature aspect ratios. Based on this information design rules are proposed that allow structures to be fully released by the notching effect. An example of a micro resonator is detailed in this paper along with micrographs.