High-performance silicon dioxide etching for less than 0.1-μm-high-aspect contact holes

We describe a method for controlling radicals in high-performance SiO2 etching of contact holes smaller than 0.1 μm using nonperfluorocompound gases (CF3I and C2F4) in an ultrahigh-frequency (UHF) plasma. Because this method allows the independent control of polymerization and etching through the selective generation of CF2 and CF3 radicals, both high etching selectivity and a high etching rate were achieved without microloading and etching stop, even for a 0.05 μm contact hole. Using this new gas chemistry, we achieved an optimum balance between polymerization and etching in 0.05-μm-diameter contact holes by controlling the flow ratio of C2F4/CF3I gas