Polycrystalline 3C-SiC thin films deposited by dual precursor LPCVD for MEMS applications

Polycrystalline silicon carbide (poly-SiC) thin films were deposited in a high-throughput, low pressure chemical vapor deposition (LPCVD) furnace using dichlorosilane (SiH2Cl2) and acetylene (C2H2) dual precursors. The deposition temperature ranged from 800 to 900 °C, and the pressure was varied between 0.46 and 5.00 Torr. Poly-SiC deposition with good uniformity is demonstrated on 150 and 100 mm diameter (1 0 0) silicon wafers. X-ray photoelectron spectroscopy (XPS) data indicated that stoichiometric SiC films were deposited over the entire range of temperatures and pressures. X-ray diffraction (XRD) data showed that all the stoichiometric films were highly textured (1 1 1) oriented, polycrystalline 3C-SiC (poly-SiC). The surface morphology and roughness as determined by atomic force microscopy (AFM) and scanning electron microscopy (SEM) indicated that the surface features consisted of spherulitic aggregates, and the surface roughness increased with increasing film thickness. The residual stress of the films varied from about 700 MPa (tensile) to −100 MPa (compressive) with the deposition pressure changing from 0.46 to 5.00 Torr at a deposition temperature of 900 °C. This observation indicates that the residual stress in poly-SiC can be controlled during deposition without affecting the process thermal budget.