EBSD Analysis of Microstructures Along the Depth Direction in Very Narrow Cu Wires

A microstructure analysis along the trench depth direction of Cu wires as a function of the purity of plating materials was carried out using electron backscattering diffraction (EBSD) analysis combined with advanced CMP technique. The Cu wire plated with high purity plating materials (6N-electrolyte and 8N-anode) was found to have 13% larger grains and 50% lower ratio of small grains (less than 45 nm) than those for the Cu wire plated with conventional purity plating materials (3N-electrolyte and 3N-anode) at the bottom region of the trench after annealing. A grain growth model in the trench depth direction was also investigated.