Doped polycrystalline 3C–SiC films with low stress for MEMS: part I. Deposition conditions and film properties

Abstract

This paper details the development of low-stress, heavily-doped polycrystalline 3C–SiC films suitable for microelectromechanical systems applications. The films were deposited on 100 mm-diameter silicon (Si) and silicon dioxide (SiO2)-coated Si wafers in a large-volume, low-pressure chemical vapor deposition furnace using dichlorosilane (DCS) (SiH2Cl2) and acetylene (C2H2) as precursors and ammonia (NH3) as the dopant source gas. The effects of NH3 and deposition pressure on the deposition rate, film residual stress and electrical resistivity were studied. Deposition parameters optimized for a combination of resistivity and residual stress yielded an average resistivity of 0.02 Ω cm and a residual tensile stress of 59 MPa as measured using wafer-scale methods. X-ray photoelectron spectroscopy indicated that the nitrogen concentration in the films was less than 0.5 at%. Variations in the flow rate of NH3 did not affect the surface roughness of the films, but changes in deposition pressure had an obvious effect on the surface roughness.