Effects of Postannealing on Electrical Characteristics and Fowler-Nordheim Current Stress Resistance of Si Oxynitride Grown in Helicon-Wave-Excited O2–N2–Ar Plasma

Abstract

The effects of post-thermal annealing in N2 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 O2–N2–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 Dit,min had the smallest value when the Si oxynitride sample was post-thermally annealed in FG (3% H2) at 300°C followed by annealing in N2 at 700°C. However, Dit,min was approximately 3.5 ×1011 eV-1cm-2, still higher than that for thermal Si oxide. The shift of the threshold voltage (Vth) after the stressing (±10 V, 100 min) was also the smallest for the Si oxynitride sample continuously annealed in FG (3% H2) and N2. The FG annealing does not necessarily improve the electrical characteristics and FN stress resistance. The N2 annealing after FG annealing is required to improve the electrical properties and FN reliability, in contrast with the case of Si oxide.