X-ray diffraction analysis of the residual stresses in self-supported CVD diamond films

We present an analysis of the microstructure and the residual stress state, both macroscopic and microscopic, of different qualities of self-supported CVD diamond films by x-ray diffraction analyses. We have measured macrosco pic residual stresses, either compressive or tensile, by the "sin(2)psi" me thod. A single line profile analysis of the x-ray diffraction peaks allowed the determination of stress fluctuations values, present inside the diamon d grains, of several GPa. Results are consistent with the model involving a non-uniform distribution of impurities inside the grains, leading to nonun iform long range stresses. When the magnitude of the stress fluctuation is high, it facilitates the appearance of cracks which propagate inside the gr ains.