Nanoelectromechanical nonvolatile memory device incorporating nanocrystalline Si dots

Abstract

A nanoelectromechanical device incorporating the nanocrystalline silicon (nc-Si) dots is proposed for use as a high-speed and nonvolatile memory. The nc-Si dots are embedded as charge storage in a mechanically bistable floating gate. Position of the floating gate can therefore be switched between two stable states by applying gate bias. Superior on-off characteristics are demonstrated by using an equivalent circuit model which takes account of the variable capacitance due to the mechanical displacement of the floating gate. Mechanical property analysis conducted by using the finite element method shows that introduction of nc-Si dot array into the movable floating gate results in reduction of switching power. High switching frequency over 1GHz is achieved by decreasing the length of the floating gate to the submicron regime. We also report on experimental observation of the mechanical bistability of the SiO2 beam fabricated by using the conventional silicon etching processes.