Mechanical properties and bonding structure of boron carbon nitride films synthesized by dual ion beam sputtering

The BCN films were synthesized on Si (110) wafers by using dual ion beam sputtering deposition from boron carbide target. The influences of ion assist source energy and N2 relative flow rate on the surface roughness, mechanical properties and chemical bonding structure of BCN films were investigated systematically. The surface roughness was measured using non-contact optical surface profilometer and the mechanical properties of BCN films were evaluated with nano-indenter. The BCN films were characterized by using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS), respectively. The results showed that the BCN films' surface roughness varied in the range of 5–15 nm, and their hardness and reduced elastic modulus fluctuated in the scope of 18–29 GPa and 192–229 GPa, respectively. When the BCN films' surface roughness varied in the range of 8–12 nm, the values of hardness and reduced elastic modulus were fluctuated slightly. The BCN films with the smoothest surface (Ra = 5 nm) and the highest hardness of 28 GPa were obtained at the ion assist source energy of 200 eV and the N2 relative flow rate of 50%. The BCN films were amorphous and contained several bonding states such as B–N, B–C and C–N with B–C–N hybridization. - Highlights: ► BCN films were synthesized using dual ion beam sputtering. ► BCN films possessed low hardness at their surface roughness of 10–11 nm. ► BCN film with the highest hardness of 28 GPa was obtained at 200 eV and 50% N2. ► The bonding structure with B–N, B–C and C–N bonds was detected in BCN films