CRYSTALLINE QUALITY AND RESIDUAL-STRESSES IN DIAMOND LAYERS BY RAMAN AND X-RAY-DIFFRACTION ANALYSES

A major problem for diamond coating applications is that diamond films tend to exhibit poor adherence on many substrates and typically disbo nd at thicknesses of the order of a few micrometers principally becaus e of residual stresses. Residual stresses are composed of thermal mism atch stresses and intrinsic tensile film stresses induced during him g rowth, Diamond films were deposited in a classical tubular microwave p lasma reactor from hydrocarbon-hydrogen-oxygen gas mixtures. The stres s level was investigated as a function of the gaseous composition (esp ecially oxygen concentration) and deposition temperature (700-900 degr ees C). Thermal stress was directly calculated from Hooke's law using a biaxial Young's modulus value of 1230 GPa for polycrystalline diamon d. Total diamond film stress was directly determined by the radius of curvature method and by x-ray diffraction using the sin(2) psi method. The microdistorsions and the size of the coherently diffracting domai ns have been determined from the broadening of the diffraction peak. W hen coupled also with a Raman study, these investigations allow discus sion of the origin of intrinsic stress. (C) 1995 American Institute of Physics.