Effect of Al films as bottom electrode material on the breakdown strength of Al2O3 thin films prepared via a sol-gel process

The deposition of Al thin films on Si and Pt substrates by DC magnetron sputtering at various deposition temperatures were investigated in this study. The morphology of the films was studied by scanning electron microscopy as a function of the deposition temperature and the thermal annealing process. Using a Pt substrate and a deposition temperature of 200 °C were determined as the optimal conditions for the Al thin film growth. Subsequently, Al2O3 thin films were deposited on Pt substrates and Pt substrates coated with an Al film, respectively, via a sol-gel process, and the electrical properties of the Al2O3 films were investigated. The results showed that the breakdown strength of Al2O3 films deposited on Pt substrates coated with an Al film at 200 °C was 30% higher than the breakdown strength of Al2O3 films deposited on Pt substrates, exceeding 575 MV/m. The high breakdown strength is attributed to the Al films deposited on the Pt substrate which effectively suppressed the Pt atom diffusion and repaired the defects of the Al2O3 films due to the anodic oxidation reaction.