Stresses and morphological instabilities in silicide/polycrystalline Si layered structures

The evolution of stress in silicide/polycrystalline Si (poly-Si) layered structures has been monitored in situ in the temperature range of 25-700°C. At elevated temperatures, the silicide/poly-Si structure becomes morphologically unstable. The grain growth of poly-Si leads to an inversion of the positions of the two layers. The in situ stress measurement shows that this structural degradation is accompanied by a substantial increase in tensile stress of around 0.4 GPa, for NiSi, Pd2Si, and PtSi. A simple calculation indicates that the magnitude of the stress increase can be accounted for, at least to a large extend, by the volume contraction caused by the grain growth of poly-Si.