STUDIES OF STRESS RELATED ISSUES IN MICROWAVE CVD DIAMOND ON (100) SILICON SUBSTRATES

Microwave plasma chemical vapor deposition (CVD) has been used to form diamond nuclei on silicon substrates after pre-treatment of the substrates which enhances nucleation. Results are presented on the effect of substrate temperatures (950-775-degrees-C) and chemistry (CH4/H-2 and the addition of CF4 and He) on the magnitude of residual stresses in the diamond films. The perfection of the films is measured by Raman spectroscopy, the strain is measured by X-ray diffraction and stress is estimated from bending of the substrate. In contrast to the expectations from the thermal expansion mismatch, namely, compressive strains in the film, we find tensile strains by measurements of the curvature of the substrate-film structure, and a factor of ten greater, apparently non-uniform, strain distribution by X-ray measurements.