Evolution of Cu metallization microstructure during electro-thermal ageing (D4.1)

Plastic deformation of Cu metallization in power devices results from a combination of heat and thermomechanical stress, mainly produced by the difference in CTE between the metal and the semiconductor and oxides. Using electron microscopy, we found that the deformation mechanisms implying dislocation activities explain a minor portion of the changes endured by the copper. It is therefore supposed that pore formation and cracks growth result from another mechanism, probably grain boundary accelerated diffusion.