Residual stress minimum in nanocrystalline diamond films

Nanocrystalline diamond films have been deposited on silicon nitride substrates by hot filament chemical vapor deposition. Gas mixtures of CH4-H-2-Ar were used with variation of the Ar/H-2 ratio in order to study the influence of the Ar content on the formation of nondiamond phases at the grain boundaries and thus in the film residual stress assessed by x-ray diffraction techniques. By varying this ratio it is possible to optimize conditions, decreasing the film's residual stress to a minimum of 0.09 GPa. (c) 2006 American Institute of Physics.