Improvement in diffusion barrier properties of PECVD W-N thin film by low-energy BF2+ implantation

The structural and electrical properties of BF2+ implanted PECVD tungsten nitride thin film were investigated. After BF2+ implantation with 40keV and 1 X 1017 B ions/cm2, W-B+-N layer was formed at the surface region of W-N films. The ternary layer maintained the microcrystalline state and prevented nitrogen out-diffusion form W-N thin film after annealing at 800 degrees C for 30 min. The overall electrical resistivity of W-B+-N/W-N thin film is 200 (mu) (Omega) cm, which is higher than that of W-N thin film because of forming the ternary phase. BF2+ implanted tungsten nitride thin film improved thermal stability against Cu diffusion more than W-N thin film.