Contact resistance reduction using vacuum loadlock system and plasma dry cleaning

The contact resistance between Si substrates and P-doped poly-Si films was investigated using a vacuum loadlock system with various wafer transfer environments. When compared to that in air atmosphere, the contact resistance was reduced by 40% and 50% in nitrogen atmosphere and under vacuum, respectively. Furthermore, the use of a plasma dry cleaning method to remove the native oxide before P-doped poly-Si deposition decreased the contact resistance by 60% compared with that in air. The surface treated with plasma dry cleaning was analyzed by secondary-ion mass spectroscopy (SIMS) and X-ray photoelection spectroscopy (XPS) and was found to be terminated by SiOxFy or SiFx, which suppressed the formation of an interface oxide and the adsorption of organic compounds.