Silicon sacrificial layer dry etching (SSLDE) for free-standing RF MEMS architectures

A novel Silicon Sacrificial Layer Dry Etching (SSLDE) technique using sputtered amorphous or LPCVD polycrystalline silicon as sacrificial layers and a dry fluorine-based (SF₆) plasma chemistry as releasing process is reported with a detailed experimental study of the release etching step. The process is capable of various applications in surface micromachining process, and can be applied in fabricating RF MEMS switches, tunable capacitors, high-Q suspended inductors and suspended-gate MOSFETs. The developed SSLDE process can release metal suspended beams and membranes with excellent performance in terms of etch rate (up to 15 μm/min), Si:SiO₂ selectivity and is fully compatible with standard MEMS processing equipment and CMOS post-processing.