Materials interaction at the nanoscale in high-k metal gate stacks: The role of oxygen

Abstract

We have studied tungsten gated hafnium oxide silicon MOSFETs and show that dissolved oxygen in the tungsten metal can diffuse to the hafnium oxide silicon interface, resulting in interfacial oxide growth and higher mobilities. These results indicate that even small amounts of dissolved oxygen in metal gates is a key issue that can impact device microstructure. We also examine the formation of this oxide and show that there is critical oxygen vacancy concentration in the hafnium oxide, below which interfacial silicon oxide formation will be favorable and above which the interfacial oxide will be unstable. copyright The Electrochemical Society.