Electrical Evaluation of Wet and Dry Cleaning Procedures for Silicon Device Fabrication

Three different cleaning procedures of silicon wafers are investigated: (i) standard wet clean, (ii) combination of UV/ oxygen and wet cleans, and (iii) entirely dry clean consisting of UV/oxygen, and thermally enhanced remote microwave plasma treatments. Their performance is experimentally compared when they are used after resist stripping, and before gate oxidation in MOS device fabrication. The electrical characteristics of subsequently formed MOS test structures show no substantial difference in the performance of devices processed using cleans (i) and (ii). The inferior distribution of the oxide breakdown events in the case of clean (iii) is attributed to the surface roughness developed using this cleaning mode.