STUDIES ON WET-CHEMICAL SURFACE CONDITIONING FOR AL2O3 PASSIVATION LAYERS DEPOSITED WITH ALD

摘要

In order to enhance the passivation quality of thin Al_2O_3 layers in an Al_2O_3/SiN_x stack an appropriatepre-deposition cleaning and wet-chemical surface conditioning plays an important role. In this study we presentfindings on the influence of wet-chemical surface conditioning on the passivation quality of thin ALD Al_2O_3 layers inan Al_2O_3/SiN_x stack. Differently terminated sample surfaces have been investigated. Two different wet-chemicaloxides, a HF last step as well as a native grown oxide of an out-of-box wafer have been analyzed regarding theirimpact on the passivation quality. Also the hydrophilic properties of the surface without a dielectric passivation layerhave been measured. We find a direct correlation of the hydrophilic properties and passivation quality of the surfacetermination on the passivation quality of the Al_2O_3/SiN_x stack. So far, a 60 s HF last step was found to be the bestsurface treatment for 5 nm Al_2O_3 layers. In comparison, a surface conditioning by wet-chemical oxides leads to lowerlifetimes. In contrast native oxides grown on cleaned wafers were found to enhance the homogeneity and thepassivation quality of Al_2O_3/SiN_x stack systems with 0.5 nm Al2O3 layers significantly. Thereby the firing stability ofthe stack system is not affected.