Tunable work functions of platinum gate electrode on HfO2 thin films for metal-oxide-semiconductor devices

The change in work function of a platinum gate electrode on a HfO2 dielectric layer was examined as a function of the annealing conditions and thickness of the HfO2 layers. HfO2 thin films with a platinum gate electrode were deposited at various thicknesses to form metal-oxide-semiconductor capacitors. An analysis of the capacitance-voltage responses, equivalent oxide thickness, and flatband voltage variations revealed effective work functions of the platinum gate electrode ranging from 4.24 to 4.98 eV. This result will provide guidelines for process-dependent metal work function modulation and integration of high-k dielectric/metal gate stacks. (c) 2008 American Institute of Physics.