Interface engineering for enhanced electron mobilities in W/HfO ₂ gate stacks

Electron mobilities of W/HfO 2 stacks were found to increase monotonically with annealing temperature with little (peak) or no degradation (IMV/cm) when compared to poly-Si devices using conventional oxides. For stacks annealed at high temperature charge pumping curves indicate low interface states densities of ∼5×10 10 charges/cm 2. Mobility enhancement can also be attributed to a structural change in the HfO 2 gate stack rather than due to only interfacial layer re-growth. © 2004 IEEE.