Evolution of intrinsic stress in nanocrystalline-diamond film deposited by continuous H[sup +] ion bombardment

Abstract

An in situ bending-plate method is used to measure intrinsic stress during the growth process of nanocrystalline-diamond film. Nanometer-sized diamond film is prepared by continuous H+ ion bombardment under different energies induced by applying a negative-bias voltage at the substrate relative to the grounded-vacuum chamber using the microwave-plasma chemical-vapor-deposition (MWPCVD) method. The effects of substrate-bias voltage, temperature, total pressure, and CH4 concentration on intrinsic stress during the film-growth process are investigated. The results indicate that high bias voltage and high substrate temperature are beneficial when synthesizing smooth nanocrystalline-diamond film. This film usually relates to high intrinsic compressive stress. This stress can be attributed to the high secondary-nucleation rate and grain-boundary density. The evolution of intrinsic stress presents a complicated process at different pressures and CH4 concentrations. The compressive stress of the film can be controlled by modifying the grain size at various deposition parameters.