Internal stress relaxation based method for elastic stiffness characterization of very thin films

Accurate measurement of the Young's modulus of films with thickness smaller than a few hundreds of nanometers remains extremely challenging. The present method disclosed here is based on the combined measurements of the internal stress using the Stoney method and of the corresponding elastic strain obtained by releasing microstructures. Experimental validation is presented for silicon nitride films. The Young's moduli of the 100, 300, and 500 nm-thick films are equal to 193 ± 20 GPa, 226 ± 22 GPa, and 208 ± 18 GPa, respectively, in good agreement with nanoindentation test results. This very simple method can potentially be used for much thinner films and extended to materials involving no internal stress.