Optimization of post-N2 treatment and undoped-Si-glass cap to improve metal wring delamination in deep submicron high-density plasma-fluorinated silica glass intermetal dielectric application

Abstract

Thermal stability of trimethylsilylated mesoporous silica thin films as the ultralow-k dielectric for copper interconnects J. Vac. Sci. Technol. B 23, 2034 (2005; 10.1116/1.2050656 X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry study of the role of Ti and TiN caps on the cobalt/SiO 2 interface Integration issues of metal line delamination from fluorinated silica glass ͑FSG͒ 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; SiO 2 ) 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.