Characteristic Change of GeO₂/Ge Interface by Hf-Post Metallization Annealing

Abstract

Si has been widely used as the primary semiconductor material for electronic device fabrication. Due to the limitation of its electrical properties such as electron and hole mobilities, however, Ge would be one of the candidates for future electronic device materials because of its higher mobilities of both carriers. However, GeO2 is known to suffer from water solubility and its reaction with the Ge substrate to cause GeO desorption at high temperature. In this research, we attempted to improve interface characteristics by depositing Hf on the GeO2/Ge structure and applying heat treatment (PMA: Post Metallization Annealing). As a result, it is clearly shown that PMA treatment for appropriate thicknesses of the deposited Hf-metal film reduces both the Dit (interface trap density) and the leakage current, and also improves the insulating properties. Thus it was confirmed that Hf-PMA is an effective solution to reduce the D it values for GeO2/Ge stacked structures.