Residual Stresses Analysis in Diamond Layers Deposited on Various Substrates

Abstract

ABSTRACTA major problem for diamond coating applications is that diamond films tend to exhibit poor adherence on many. substrates and typically disbond at thicknesses of the order of few micrometers due especially to residual stresses. Residual stresses in diamond are composed of thermal expansion mismatch stresses and intrinsic stresses induced during film growth. Diamond films were deposited in a classical microwave plasma reactor from hydrocarbon-hydrogen-oxygen gas mixtures. Thermal stresses were directly calculated from Hook's law. On silicon substrate, intrinsic stresses were deduced by difference from measurements of total stresses either by the curvature method or by X-ray diffraction using the sin 2ψ method. These investigations allow us to discuss the origin of the intrinsic stresses. The residual stress level was also investigated by Raman spectroscopy as a function of the deposition conditions and substrate materials (SiO2, Si3N4, Si, SiC, WC-Co, Mo and Ti-6A1-4V). We show that the thermal stresses are often preponderant.