Characteristics of SiCN microstructures for harsh environment and high-power MEMS applications

This paper describes a novel processing technique for the fabrication of polymer-derived silicone carbonitride (SiCN) microstructures for extreme microelectromechanical system (MEMS) applications. A polydimethylsiloxane (PDMS) mold was formed on an SU-8 pattern using a standard UV photolithographic process. Next, the liquid precursor, polysilazane, was injected into the PDMS mold to fabricate free-standing SiCN microstructures. Finally, the solid polymer SiCN microstructure was crosslinked using hot isostatic pressure at 400 °C and 205 bar. The optimal pyrolysis and annealing conditions to form a ceramic microstructure capable of withstanding temperatures over 1400 °C were determined. Using the optimal process conditions, the fabricated SiCN ceramic microstructure possessed excellent characteristics including shear strength (15.2 N), insulation resistance (2.163×1014 Ω cm), and BDV (1.2 kV, minimum). Since the fabricated ceramic SiCN microstructure has improved electrical and physical characteristics compared to bulk Si wafers, it may be applied to harsh environments and high-power MEMS applications such as heat exchangers and combustion chambers.