Effect of Rapid Thermal Annealing on Si-Based Dielectric Films Grown by ICP-CVD

Silicon nitride, silicon oxide, and silicon oxynitride thin films were deposited on the Si substrate by inductively coupled plasma chemical vapor deposition and annealed at 1100 °C for 3 min in an Ar environment. Silicon nitride and silicon oxide films deposited at ratios of the reactant flow rates of SiH₄/N₂ = 1.875 and SiH₄/N₂O = 3, respectively, were Si-rich, while Si excess for the oxynitride film (SiH₄/N₂/N₂O = 3:2:2) was not found. Annealing resulted in a thickness decrease and structural transformation for SiO and SiN films. Nanocrystalline phases of Si as well as α- and β-Si₃N₄ were found in the annealed silicon nitride film. Compared to oxide and nitride films, the oxynitride film is the least susceptible to change during annealing. The relationship between the structure, composition, and optical properties of the Si-based films has been revealed. It has been shown that the calculated optical parameters (refractive index, extinction coefficient) reflect structural peculiarities of the as-deposited and annealed films.