Modeling and Design of a Low-Voltage SOI Suspended-Gate MOSFET (SG-MOSFET) with a Metal-over-Gate Architecture

A novel MEMS device architecture: the SOI SGMOSFET, which combines a solid-state MOS transistor and a suspended metal membrane in a unique metal-over-gate architecture, is proposed. A unified physical analytical model (weak, moderate and strong inversions) is developed and used to investigate main electrostatic characteristics in order to provide first-order design criteria for low-voltage operation and high-performance. It is demonstrated that the use of a thin gate oxide (<20nm) is essential for a high Con/Coff ratio (>100) and a low spring constant (<100N/m) is needed for low voltage (<5V) actuation. An adapted fabrication process is reported.