First-principles exploration of the impact of [Si—C] and [N=C] bonds in SiCN films: Composition, structure, and properties

Abstract

Silicon carbon nitride (SiCN) is a ceramic material known for its exceptional thermal stability, chemical resistance, and mechanical strength. Compared to silicon nitride (Si3N4), SiCN offers enhanced material properties due to its tunable elemental composition and microstructure. However, the precise relationship between the microstructure of SiCN and its material properties remains inadequately understood. This study aims to elucidate the structure–property relationship by correlating the bonding environment of SiCN with its material properties. Specifically, this work investigates the effects of incorporating [Si–C] and [N=C] bonds into amorphous SiN films. Amorphous SiCN models with diverse Si, N, and C compositions were constructed and analyzed in terms of film stability, dielectric constant, refractive index, bandgap, bulk modulus, and bond densities. We find that [N=C] bonds significantly reduce the dielectric constant and mechanical strength, while [Si–C] bonds preserve mechanical properties but increase the dielectric constant. This study can provide valuable insights for tailoring these properties to meet specific application requirements.