Oblique angle deposition of boron carbide films by magnetron sputtering

Many applications of boron carbide (B4C) films entail deposition on non-planar substrates, necessitating a better understanding of oblique angle deposition phenomena. Here, we systematically study the effect of substrate tilt on properties of B4C films with thicknesses up to 10 mu m deposited by direct current magnetron sputtering. Results show that all films are amorphous and columnar with an average column width of similar to 100 nm, independent of substrate tilt. Column tilt angles are limited to similar to 20 ?degrees even for substrate tilt of 80 ?degrees . Film density, residual stress, and the refractive index weakly (within similar to 20 %) depend on substrate tilt. Oxygen impurities bond preferentially with carbon atoms in inter-columnar regions. Substrate tilt has a major effect on mechanical properties that decrease by & SIM; 50 %, suggesting weak interconnection between nano-columns. Implications of these observations for the deposition onto non-planar substrates are discussed.