Growth and characterization of nitrogen-doped polycrystalline 3C-SiC thin films for harsh environment MEMS applications

Abstract

Polycrystalline 3C-SiC films, in situ doped with nitrogen, are grown by low-pressure chemical vapor deposition (LPCVD) on 100 mm Si (1 0 0) wafers at 800 °C using methylsilane and ammonia precursors. The effects of NH3 and dichlorosilane precursor, as an additional silicon source, on material properties such resistivity, residual stress, strain, strain gradient as well as crystallinity and surface morphology are investigated. By varying these parameters, the electrical and mechanical properties of the films are optimized for MEMS applications. Films with a resistivity of 0.026 ± 0.001 Ω cm, residual stress of 254 ± 16 MPa and strain of 4.5 × 10−4, corresponding to the biaxial modulus of 564 GPa, and strain gradient of 5.8 × 10−4 µm−1 are achieved.