Low temperature (< 400℃) Al_2O_3 ultrathin gate dielectrics prepared by shadow evaporation of aluminum followed by nitric acid oxidation

摘要

A cost-effective method of shadow evaporation of aluminum is adopted to prepare ultrathin aluminum film. The formation of different thicknesses of aluminum film on one wafer was demonstrated. The mask sheltered the wafer from the pure aluminum source to achieve ultrathin aluminum film. Aluminum oxide (Al_2O_3) was obtained by nitric acid oxidation of the evaporated aluminum directly at room temperature. In this work, the leakage current in the sample of equivalent oxide thickness of 2 nm is one order of magnitude reduction in comparison with that in the conventional thermal SiO_2 sample and the charge trapping phenomenon is not obvious.