Study of stress in microwave plasma chemical vapor deposited diamond films using X-ray diffraction

Residual stress in polycrystalline diamond films has been studied. Uniform polycrystalline diamond films were deposited on 3.0in. diameter silicon substrates in a microwave plasma chemical vapor deposition (MPCVD) system. The effects of CH4/H-2 ratio, pressure, and power Variation on film stress were investigated. The macro-stress, or uniform stress, in the films was measured using the X-ray diffraction (XRD) d-sin(2) psi technique. In general, [220]-oriented films exhibited tensile stress and [111]-oriented films were in compression. The micro-stress, or non-uniform stress, calculated from diffraction peak broadening, was observed to be tensile for all samples. Films of relatively small grain size and [220] orientation showed both the highest micro-stress and the highest macro-stress. Film morphology was analyzed using scanning electron microscopy (SEM) and atomic force microscopy (AFM), while the film texture was studied using XRD. Significant non-diamond carbon was incorporated in [220]-oriented diamond as estimated from the intensity of the broad 1580 cm(-1) peak in the Raman spectra. Much less non-diamond carbon was detected in [111]-oriented diamond films. Good correlation between film morphology and measured stress was observed.