Improvement on properties and reliability of ultra-thin silicon oxide (3-5nm) grown by microwave plasma afterglow at the low temperatures using mixtures of N2O and O-2

Ultra-thin silicon oxides (4 nm) with excellent quality were grown by using mixture of N2O and O-2 plasma in a microwave afterglow plasma oxidation sy stem. The electrical breakdown fields of oxide grown with a mixture of N2O and O-2 plasma are comparable with that of conventional thermally grown oxi des. The interface state densities are lower and charge to breakdown are hi gher than that of oxide grown in traditional thermal furnace. The optimal i nterface state density (similar to 3 X 10(10) cm(-2) eV(-1)) could be achie ved by tuning the N2O/O-2 ratio. The oxides grown with a lower microwave po wer 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 flo w rate. Resistance to tunneling current stress increased as the ratio of N2 O/O-2 in plasma is higher. All these improvements could be attributed to th e incorporation of nitrogen into oxides grown at lower temperatures in our novel system. (C) 1999 Published by Elsevier Science B.V. All rights reserv ed.