Interface dipole and effective work function of Re in Re∕HfO2∕SiOx∕n-Si gate stack

Abstract

Fermi level pinning at the Re∕HfO2 interface and its contribution to the Re interface work function in the Re∕HfO2∕SiOx∕n-Si stack were investigated using x-ray and ultraviolet photoelectron spectroscopy in conjunction with capacitance-voltage (C-V) measurements. Photoemission results showed that the Fermi level was partially pinned at the Re∕HfO2 interface, resulting in a 0.5eV interface dipole and 5.0eV interface work function between Re and HfO2. In contrast, C-V measurement of the Re∕HfO2∕SiOx∕n-Si stack showed a 4.7–4.8eV interface work function. The difference in Re interface work functions is discussed in terms of contributions of additional interface dipoles in the stack.