Intrinsic stress evolution in diamond films prepared in a CH4-H-2-NH3 hot filament chemical vapor deposition system

The intrinsic stress in diamond films prepared in a CH4-H-2-NH3 hot filamen t chemical vapor deposition system has been investigated by the substrate c urvature technique as a function of film thickness (2.2-50 mu m) and ammoni a concentration (0-1.4%). Our results indicated that the him stress changed from compressive to tensile with the increase of film thickness and diamon d quality at a constant ammonia concentration of 0.5%. The existence of a n on-diamond phase was found to be beneficial to the relaxation of intrinsic tensile stress in the films. The intrinsic stress in diamond films was tens ile at an ammonia concentration from 0 to 1.4%, while the maximum tensile s tress existed at 0.75% NH3. The possible origin of intrinsic tensile stress was discussed. (C) 2000 Elsevier Science S.A All rights reserved.