Electrical characterization of Al2O3-SiO2 MOS structures

A comparative capacitance voltage method is used to investigate the equivalent thickness reduction during post metallization annealing of thermally grown ultrathin (similar to 15-27 Angstrom) oxides. It is found that a double layered dielectric consisting of a thin Al2O3-SiO2 sandwich is appropriate to describe both the increased capacitance and the nearly unaltered current after anneal. It is further shown that the impact of initial thickness and method of growth - in a conventional furnace or by rapid thermal oxidation - on the equivalent thickness reduction is negligible.