In-situ investigation by X-ray diffraction and wafer curvature of phase formation and stress evolution during metal thin film - silicon reactions

Metal silicides are important materials for microelectronic devices. They are forined via a solid state reaction between a metal film and a silicon substrate. Mechanical stresses arise during this reactive diffusion process and are investigated by x-ray diffraction and curvature measurements. The different phases that form, yield distinct stress evolutions related to the volume change and to the mechanical properties of the silicides. In the formed silicide layers strains can vary strongly from one grain to the other as shown ill NiSi, where it is attributed to the strong anisotropy in thermal expansion.