Electrical characterization of metal-oxide-semiconductor capacitors with anodic and plasma-nitrided oxides

We have studied two novel techniques that should inherently be more uniform than current mainstream processes used to produce silicon dioxide or nitri ded-oxide gate insulators. Anodic films were fabricated by anodizing Si waf ers in Hel solutions, and thermal oxide films were nitrided in N2O plasmas produced with an electron-cyclotron resonance source. Using typical polysil icon-gate test structures, the electrical characteristics are obtained and compared to thermal oxides. Both techniques can produce thin films (<15 nm thick) with interface state densities and leakage currents initially compar able to their thermal oxide counterparts, if the films are subjected to rap id thermal annealing at temperatures of 950 degrees C. The annealed films a re subjected to high-field (greater than or equal to 8 MV/cm) Fowler-Nordhe im stress and the buildup of trapped charge is monitored as a function of t ime. Anodic films are found to have moderately higher bulk and interface tr ap generation rates than the thermal control. Thinner anodic oxides. which were grown at slower rates, had better properties than thicker anodic oxide s, suggesting that even slower growth rates could yield anodic oxides with improved electrical properties. (C) 2000 American Vacuum Society. [S0734-21 01(00)07802-7].