Cubic boron nitride (c-BN) thick film growth was attempted by the addition of hydrogen for residual stress reduction and by using a nanocrystalline diamond (NCD) buffer layer for stabilizing the turbostratic boron nitride interfacial layer. The c-BN films were deposited by the unbalanced magnetron sputtering method. Thin (100 mu m) Si strips (3 x 40 mm(2)) were used as substrates. A boron nitride target was used, which was connected to a radio frequency power supply at 400 W. High frequency power connected to a substrate holder was used for self-biasing of -40 V. The deposition pressure was 0.27 Pa with a flow of Ar (18 sccm)-N-2 (2 sccm) mixed gas. Hydrogen gas of 2 sccm was added to the Ar-N-2 mixed gas. The effect of the addition time of the hydrogen to the Ar-N-2 gas during deposition was investigated and found to be critical to the occurrence of the delamination of the c-BN film on the NCD buffer layer. As the addition of the hydrogen was delayed, the delamination started later. C-BN film of 3 mu m thickness adherent to the substrate was obtained. (C) 2013 Elsevier B.V. All rights reserved.