A Low-Leakage Epitaxial High-κ Gate Oxide for Germanium Metal–Oxide–Semiconductor Devices

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• 作者：Chengqing Hu ; Martin D. McDaniel ; Aiting Jiang ; Agham Posadas ; Alexander A. Demkov ; John G. Ekerdt ; Edward T. Yu
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：March 2, 2016
• 年：2016
• 卷：8
• 期：8
• 页码：5416-5423
• 全文大小：424K
• ISSN：1944-8252

文摘

Germanium (Ge)-based metal–oxide–semiconductor field-effect transistors are a promising candidate for high performance, low power electronics at the 7 nm technology node and beyond. However, the availability of high quality gate oxide/Ge interfaces that provide low leakage current density and equivalent oxide thickness (EOT), robust scalability, and acceptable interface state density (D_it) has emerged as one of the most challenging hurdles in the development of such devices. Here we demonstrate and present detailed electrical characterization of a high-κ epitaxial oxide gate stack based on crystalline SrHfO₃ grown on Ge (001) by atomic layer deposition. Metal–oxide–Ge capacitor structures show extremely low gate leakage, small and scalable EOT, and good and reducible D_it. Detailed growth strategies and postgrowth annealing schemes are demonstrated to reduce D_it. The physical mechanisms behind these phenomena are studied and suggest approaches for further reduction of D_it.