Processing dependence of metal/tunnel-oxide/silicon junctions

Abstract

The effects of process variations on the fixed‐charge density, interface‐state density, and tunneling properties of tunnel oxides on (100) silicon are discussed. Annealing the oxide in nitrogen reduces the fixed‐charge and interface‐state densities substantially, but also causes a marked increase in oxide capacitance. Anneals in forming gas before metallization alter the interface‐state distribution and decrease the insulating qualities of the tunneling oxides. Postmetallization anneals in forming gas reduce the interface‐state density to 1×10¹¹ cm⁻² eV⁻¹ or below, and appear not to affect the current through the oxide. No evidence for metal‐induced interface states is observed.