Use of scanned laser annealing to control the bamboo grain length of Cu interconnects

Abstract

Microstructural evolution induced by scanned laser annealing (SLA) of Cu interconnects was found to produce unique large-grained “bamboo” grain structures, with bamboo grain lengths up to ten times the linewidth. These bamboo grain lengths are shown to depend on the scan rate and laser power. By comparing results from experiments on different structures with grain growth simulations, the bamboo grain length induced by SLA is shown to be a strong function of the thermal profile, where steeper thermal profiles yield longer bamboo grains.