High performance gate stack fabrication process of Ge MOS structure for future electronic devices

Abstract

Abstract-Si has been widely used as primary semiconductor materials 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, since GeO 2 which composed of Ge-O chemical bonds is known to have water solubility and it reacts with Ge substrates at high temperature, it is well known that GeO desorption occurs at GeO 2 /Ge interface during higher temperature annealing, as well as during the course of higher temperature oxidation process itself. In this research, we attempted to improve interface characteristics by depositing Hf on the GeO 2 /Ge structure and applying heat treatment (PMA: Post Metallization Annealing). As a result, it is clearly shown that the decrease of D it value by the PMA, and the leakage current was reduced and insulating property was improved by applying PMA. We consider that a slight amount of Hf buried the GeO 2 film by Hf-PMA and the bonding strength of Ge-O became stable. It was confirmed that Hf-PMA is effective for GeO2/Ge stacked structure as a solution to reduce the D it values.