Effects of Postannealing on Electrical Characteristics and Fowler-Nordheim Current Stress Resistance of Si Oxynitride Grown in Helicon-Wave-Excited O₂–N₂–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 resistance were investigated for Si oxynitride grown in helicon-wave excited O 2 –N 2 –Ar plasma. The X-ray photoelectron spectroscopic data indicated growth of the Si oxynitride. The capacitance-voltage characteristics were measured to evaluate the electrical qualities of the grown Si oxynitride. The minimum interface state density D it,min had the smallest value when the Si oxynitride sample was post-thermally annealed in FG (3% H 2 ) at 300°C followed by annealing in N 2 at 700°C. However, D it,min was approximately 3.5 ×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 continuously 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 annealing after FG annealing is required to improve the electrical properties and FN reliability, in contrast with the case of Si oxide.