Pulsed DC Sputter Deposition of Stable Turbostratic Boron Nitride Thin Films

ABSTRACT Boron nitride (BN) is considered for several applications in microelectronics, such as thermal management, optoelectronics, or as memristors. BN can be deposited with different deposition methods, but any integration in the back‐end‐of‐the‐line limits the deposition temperature to approximately 400°C. Further requirements include high crystal quality, sufficient film stability, and a high deposition rate to limit process costs. In particular, investigations into thin film stability and high deposition rates have rarely been conducted. Here, we propose reactive pulsed direct current sputtering at 250°C from a pure boron target and demonstrate the deposition process for stable nanocrystalline turbostratic BN. A substrate bias voltage between the plasma and sample reduces excess boron in the film and enhances its crystallinity. The process effectively prevents the formation of boric acid and ammonium borate hydrate. The stable BN films have a crystallite size of approximately 5 nm and an out‐of‐plane texture. Leakage current investigations demonstrate the insulating properties of the films. A high deposition rate of 81.6 nm min – 1 and the use of state‐of‐the‐art sputter hardware allow the immediate integration of sputtered BN into semiconductor device process lines.