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

TLDR: In this article, two novel techniques that should inherently be more uniform than current mainstream processes used to produce silicon dioxide or nitrided-oxide gate insulators were studied and compared to thermal oxides.

Abstract: We have studied two novel techniques that should inherently be more uniform than current mainstream processes used to produce silicon dioxide or nitrided-oxide gate insulators. Anodic films were fabricated by anodizing Si wafers in HCl solutions, and thermal oxide films were nitrided in N2O plasmas produced with an electron-cyclotron resonance source. Using typical polysilicon-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 comparable to their thermal oxide counterparts, if the films are subjected to rapid thermal annealing at temperatures of 950 °C. The annealed films are subjected to high-field (⩾8 MV/cm) Fowler–Nordheim stress and the buildup of trapped charge is monitored as a function of time. Anodic films are found to have moderately higher bulk and interface trap generation rates than the thermal control. Thinner anodic oxides, which w...