Local distribution of residual stress of Cu in LSI interconnect

Abstract

Local distributions of crystal orientation and residual stress of Cu lines (600nm and 400nm) in large-scale integrated circuit (LSI) interconnects are visualized by electron backscatter diffraction (EBSD). The crystal orientation distribution is random and texture is not observed. Bamboo grain boundary structures form with decreasing Cu line width. The Wilkinson EBSD method indicates that the residual elastic stress of a Cu line in an LSI interconnect is locally high at twin boundaries, grain boundaries, and the Cu/dielectric interface. The local distributions of residual elastic stress at these boundaries and the interface should induce preferential crack nucleation.