Doped Polycrystalline 3C-SiC Films Deposited by LPCVD for Radio-Frequency MEMS Applications

Polycrystalline 3C-SiC films are deposited on SiO₂ coated Si substrates by low pressure chemical vapour deposition (LPCVD) with C₃H₈ and SiH₄ as precursors. Controlled nitrogen doping is performed by adding NH₃ during SiC
growth to obtain the low resistivity 3C-SiC films. X-ray diffraction (XRD) patterns indicate that the deposited films are highly textured (111) orientation. The surface morphology and roughness are determined by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The surface features are spherulitic texture with average grain size of 100nm, and the rms roughness is 20nm (AFM 5×5μm images). Polycrystalline 3C-SiC films with highly orientational texture and good surface morphology deposited on
SiO₂ coated Si substrates could be used to fabricate rf microelectromechanical systems (MEMS) devices such as SiC based filters.