Preparation of B–C–N films by magnetron sputtering with different N2/Ar flow ratio

Amorphous B–C–N films were fabricated on silicon (100) substrates using radio frequency reactive magnetron sputtering technique with variable N2/Ar flow ratios. The structures, chemical bonding and mechanical properties were characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and nanoindentation. We found that the N concentration is insensitive to the increment of N2/Ar flow ratio while the B concentration decreases and C concentration increases. All B–C, C–N, and B–N bond contents increase as the N2/Ar flow ratio varies from 1/10 to 5/10. Further improving the N2/Ar flow ratio will promote N atoms prior to bonding with C, resulting in decreased B–C and increased C–N bond content, respectively. The changes of bond content lead to a shift of the main peaks of B1s, C1s, and N1s spectra toward higher binding energies. The hardness of B–C–N thin films is almost invariant with the N2/Ar flow ratio.

Research highlights
► Bond contents can give semi-quantitative estimation of bonding level.
► Bond contents can greatly affect mechanical properties of a material.
►  B-C-N coatings were produced by magnetron sputtering technique.
► Relation of bond content and mechanical properties in B-C-N films was studied.