Influence of grain orientation on the microstructural characterization in cu during (self)-anneal using a surface acoustic wave technique

Abstract

This paper describes the influence of microstructure, or more specifically grain orientation and grain size, on the in-line monitoring of copper interconnect properties during (self)-anneal using surface acoustic wave spectroscopy (SAWS). In electroplated Cu after (sell)anneal the SAWS frequency is lower for samples annealed at higher temperature because of the lower porosity induced elasticity. In sputtered Cu, the SAWS frequency shows a clear correlation with grain size, which is induced by a strong re-orientation of the copper film from the as-deposited (111) texture. (E=190 GPa) to a strongly (100) textured super grain structure (E=78GPa).