Preparation and characterization of low-dielectric-constant F-doped SiOCN films by PECVD

F-doped SiOCN films with low dielectric constant have been prepared using SiH₄, C₂F₆ and N₂O as reactants by PECVD, and characterized by X-ray photoelectron spectroscopy (XPS), capacitance -voltage (C-V) and current-voltage (I-V) measurements, and nano-indenter. With an increment of the flow rate of C₂F₆, the concentrations of fluorine and carbon incorporated in the films increase, and the concentration of nitrogen decreases. This leads to a decrease in the dielectric constant of the film. When the flow rate of C₂F₆ is 750 sccm, the percentages of C and F elements amount to 5.2% and 9.9%, respectively. Meanwhile, the resulting dielectric constant is reduced to 2.6, and the leakage current density is lower than 3× 10^-8 A/cm² at 1MV/cm. The hardness and Young´s modulus of the films are higher than 3 GPa and 84 GPa, respectively. It is thus believed that the introduction of carbon and fluorine can lower the dielectric constant of the films, and the presence of N can improve the mechanical properties of film.