Improvement on properties and reliability of ultra-thin silicon oxide (3-5 nm) grown by microwave plasma afterglow at the low temperatures using mixtures of N₂O and O₂

Ultra-thin silicon oxides (4 nm) with excellent quality were grown by using mixture of N₂O and O₂ plasma in a microwave afterglow plasma oxidation system. The electrical breakdown fields of oxide grown with a mixture of N₂O and O₂ plasma are comparable with that of conventional thermally grown oxides. The interface state densities are lower and charge to breakdown are higher than that of oxide grown in traditional thermal furnace. The optimal interface state density (approx. 3 × 10¹⁰ cm^-2 eV^-1) could be achieved by tuning the N₂O/O₂ ratio. The oxides grown with a lower microwave power and a lower gas flow rate possess lower interface state density. Higher value of charge to breakdown could be found in oxides grown at low gas flow rate. Resistance to tunneling current stress increased as the ratio of N₂O/O₂ in plasma is higher. All these improvements could be attributed to the incorporation of nitrogen into oxides grown at lower temperatures in our novel system.