Optimization of post-N-2 treatment and undoped-Si-glass cap to improve metal wring delamination in deep submicron high-density plasma-fluorinated silica glass intermetal dielectric application

Abstract

Integration issues of metal line delamination from fluorinated silica glass (FSG) in deep submicron intermetal dielectric applications were investigated in this study. A metal line peeled off after a nonoptimized in situ deposition of undoped-silicon-glass (USG; SiO2) capping layer followed the post-FSG-chemical mechanical polishing N-2 treatment. It was found that higher bias power and longer process time of N-2 treatment led to more active fluorine species diffusing from the FSG films to the USG surface, which might react with subsequent Ti/TiN/W metal layer and result in metal delamination. Using plasma-enhanced N-2 treatment and ex situ USG capping with lower initial deposition temperature by extra cooling step, the stability of the FSG films was improved and resulted in a robust structure without metal peeling. (C) 2004 American Vacuum Society.