Electrical, mechanical and metal contact properties of polycrystalline 3C-SiC films for MEMS in harsh environments

Abstract

Polycrystalline 3C-SiC (poly-SiC) is a promising structural material for microelectromechanical systems (MEMS) used in harsh environments. In order to realize poly-SiC based MEMS devices, the electrical, mechanical and metal contact properties of poly-SiC have to be optimized. The poly-SiC films, reviewed here, are deposited by low pressure chemical vapor deposition using 1,3-disilabutane (DSB) as the single precursor, and are in-situ doped using NH 3 (n-type) and trimethylaluminum (p-type). The effects of doping on film structure, resistivity, residual stress and strain gradient have been examined. A bi-layer deposition scheme is developed to minimize the strain gradient without compromising the electrical resistivity of film. The temperature coefficient of resistivity (TCR) is also characterized and is found to be negative over 304–638 K. Ohmic nickel and platinum contacts to n-type doped poly-SiC are obtained and characterized. A stable metal contact up to 300 °C in air is demonstrated.