Interface model for HfO2 gate stack from first principles calculations and its application to nanoscale device simulations

Rigorous first-principles calculations are performed to address the interface properties of HfO2 gate stacks with interlayer (IL). The band-gap and dielectric constant change nonabruptly at the HfO2/IL and IL/Si interfaces with transition regions of a few angstrom wide. Device-level simulations are then performed with the interface properties reflected, and electrostatics, gate-leakage and drain currents are found to be substantially influenced by the presence of the transition regions. Based on the findings, the equivalent single-layer model as a practical guide to the modeling and simulation of HfO2 gate stacks is proposed.