Cubic boron nitride films prepared by reactive r.f. and d.c. sputtering from different boron containing targets

• Published in: Surface & coatings technology 1995-10, Vol.74 (1-3), p.717-722
• Main Authors: Schütze, A., Bewilogua, K., Lüthje, H., Kouptsidis, S., Jäger, S.
• Format: Article
• Language: English
• Subjects: Conductive target; Cross-disciplinary physics: materials science; rheology; Cubic boron nitride; Deposition by sputtering; Exact sciences and technology; IR spectroscopy; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Physics; Reactive sputtering
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/0257-8972(95)08312-X

Cubic boron nitride (c-BN) films have been deposited by reactive r.f. sputtering in Ar-N 2 mixtures, using both insulating hexagonal boron nitride (h-BN) and electrically conducting boron carbide (B 4C) targets. The relative nitrogen-flow in the sputter gas was varied between 0% and 100%. The substrate electrode was operated either with an r.f. or d.c. power supply. As a measure for the c-BN content the ratio of the infrared absorption bands near 1100 cm −1 (c-BN) and 1400 cm −1 (h-BN) was used. A simple approximation allows estimation of the real content of the cubic phase from these ratios. For the h-BN target, maximum values of the c-BN content occurred in the range 1%–10% N 2. For the B 4C target, more than 10% N 2 was needed to obtain c-BN containing films. For both target materials the growth of the cubic phase is correlated to a B/N ratio near to unity. Many films with high c-BN contents tended to peel off from the substrate. A well adhering film exhibited a very high hardness of 50–60 GPa measured with a nanoindentor set-up. First experiments using a d.c. magnetron sputter apparatus with a B 4C target revealed that c-BN can also be prepared by d.c. sputtering.