Effects of postannealing on electrical characteristics and Fowler-Nordheimcurrent stress resistance of Si oxynitride grown in helicon-wave-excited O-2-N-2-Ar plasma

The effects of post-thermal annealing in N-2 and/or forming gas (FG) on the electrical characteristics and Fowler-Nordheim (FN) current stress resista nce were investigated for Si oxynitride grown in helicon-wave excited O-2-N -2-Ar plasma. The X-ray photoelectron spectroscopic data indicated growth o f the Si oxynitride. The capacitance-voltage characteristics were measured to evaluate the electrical qualities of the grown Si oxynitride. The minimu m interface state density D-it,D-min had the smallest value when the Si oxy nitride sample was post-thermally annealed in FG (3% H-2) at 300 degrees C followed by annealing in N-2 at 700 degrees C. However, D-it,D-min was appr oximately 3.5 x 10(11) eV(-1) cm(-2), still higher than that for thermal Si oxide. The shift of, the threshold voltage (V-th) after the stressing (+/- 10 V, 100 min) was also the smallest for the Si oxynitride sample continuo usly annealed in FG (3% H-2) and N-2 The FG annealing does not necessarily improve the electrical characteristics and FN stress resistance. The N-2 an nealing after FG annealing is required to improve the electrical properties and FN reliability, in contrast with the case of Si oxide.