MICROSTRUCTURE AND RESIDUAL-STRESS OF VERY THIN MO FILMS

Very thin sputtered Mo films (thicknesses < 800 Angstrom) have been in vestigated in order to gain a better understanding of the relationship between the development of microstructure, morphology and residual st ress. Mo films were grown by planar magnetron sputtering (3 mTorr Ar) onto Si substrates with native oxide. Examination of a large number of Mo films using double crystal diffraction topography showed that a la rge compressive stress (similar to 1 GPa) was accumulated in the thinn est films studied (similar to 33 Angstrom). The film stress relaxed wi th increasing thickness and eventually crossed over to the tensile reg ime. The microstructure of these films have been studied using two tec hniques, transmission electron microscopy and grazing incidence X-ray scattering. The evolution of microstructure in Mo films has been exami ned by monitoring the in-plane grain size as a function of him thickne ss, beginning with 33 Angstrom thick films. Both techniques showed tha t the grain width increased rapidly at the earliest stages of growth, but exhibited a slower increase in growth by thicknesses similar to 80 0 Angstrom.