DC arc plasma generation and thin film deposition from an industrial scale TiB2 cathode

TiB₂ is well established as a superhard coating material with a high melting point and a low friction coefficient. However, its brittle nature limits its utilization in arc evaporation, a commonly used technique in the thin film industry. In this work, we report the use of circular TiB₂ cathodes, 100 mm in diameter, for thin film deposition in a DC vacuum arc system utilizing an industrial arc plasma source. We demonstrate that arcing from the TiB₂ cathode is stable, and at a distance of 20 cm from the cathode surface, a deposition rate of 100 nm/min on a Si substrate heated to 500 °C is achieved. Notably, the resulting film composition exhibits a B/Ti ratio of approximately 1.2, with a measured hardness of around 34 GPa. By evaluating the plasma ion composition and analyzing the deposited films at varying distances and angles from the cathode surface normal, a spatial dependence of the boron content was observed. Shifting the substrate position 10 cm off-axis from the cathode center increased the B/Ti ratio in the film to approximately 1.5, resulting in a hardness of up to ~38 GPa. Plasma diagnostics confirmed a higher boron ion content at larger angles from the surface normal. These results demonstrate the high potential of industrial cathodic arc systems as efficient and practical methods for the synthesis of metal boride coatings. • Stable arcing from a 100 mm TiB₂ cathode across a wide range of conditions • Deposition rates up to 100 nm/min and obtained hardness up to 34 GPa • Plasma–film correlation indicates tunable film composition and properties