Synthesis of Boron Nitride Films Using Electron–Cyclotron Resonance Microwave Plasma and an H2–BF3–N2–Ar–He Gas System†

Boron nitride (BN) films with high crystallinity and phase purity (>80 %) in the cubic phase were synthesized over large areas using fluorine chemistry and electron-cyclotron resonance (ECR) microwave plasma. Plasma-enhanced fluorine chemistry was provided by a complex H 2 -BF 3 -N 2 -Ar-He gas mixture. Each component of the mixture was optimized in accordance with its function. Such a procedure allowed the preparation of thick cBN films at a bias voltage as low as -30 V. Micrometer-thick cBN films exhibiting columnar growth were obtained. However, ion bombardment was still indispensable for the cBN growth. The effects of deposition time and ion bombardment on the phase purity and crystallinity of the cBN films were investigated.