Nitridation of Silicon Oxide Surfaces by Fluorination and Subsequent Exposure to Atomic Nitrogen

Nitrogen incorporation into oxide surfaces is required to prevent the penetration of boron from the polycrystalline silicon gate to the substrate in metal-oxide-semiconductor devices. We incorporate nitrogen only into the oxide surfaces by fluorination at room temperature and a subsequent atomic nitrogen treatment at temperatures below 550°C. Incorporated nitrogen atoms are found to be bound to silicon atoms and oxygen atoms by X-ray photoelectron spectroscopy. Moreover, surface roughness is improved by the nitridation process. The proposed technique is a unique process to obtain high-quality ultrathin dielectrics.