Ultimate technology for micromachining of nanometric gap HF micromechnical resonators

We demonstrate in this paper a fabrication process for the realization of nanometric lateral gap micromechanical resonators. This two-masks self-aligned process relies on surface micromachining of silicon to achieve high aspect ratio lateral capacitive gaps between a mobile resonator and its fixed electrodes down to 60nm. Two structural materials were used for the vibrating parts : Single crystal silicon and disilane-based LPCVD polysilicon. Thanks to this process, resonating devices have been demonstrated, among which lateral clamped-clamped beam resonators, impact-driven resonators, and paralleled identical resonators structures, with resonance frequency ranging from 5MHz to 35MHz.