Low contact resistance metallization for gigabit scale DRAMs using fully-dry cleaning by Ar/H2 ECR plasma

This paper describes a fully-dry cleaning technique with Ar/H₂ Electron Cyclotron Resonance (ECR) plasma as a low contact resistance metallization technology for gigabit scale DRAM contacts. Extremely low contact resistances of 296 Ω and 350 Ω for 0.3 μm contact diameter with aspect ratio of 7 were realized on n+ and p+ diffusion layers, respectively. No leakage current was observed. By using this technology, a DRAM ULSI, which was planarized by Chemical Mechanical Polishing (CMP) and had deep contact holes with aspect ratio of 6, was successfully fabricated