Silicon-Atom Induced Fermi-Level Pinning of Fully Silicided Platinum Gates on HfO2 Dielectrics

Fully silicided platinum gates have been proposed as metal gate electrodes for scaled complementary metal oxide semiconductor field-effect transistors (CMOSFETs). The Pt monosilicide (PtSi) phase was formed on gate dielectrics by a full silicidation reaction at 400°C. PtSi gate electrodes on SiO2 possess a high effective work function of 4.9 eV, which could be used as a possible metal gate electrode for p-MOSFETs, while at the PtSi/HfO2 interface, Fermi-level pinning is observed independent of the PtSi fabrication process. The Fermi-level pinning at the PtSi/HfO2 interface is comparable to that at the poly-Si/HfO2 interface, and Fermi-level pinning does not occur at the Pt/HfO2 interface. These results show that Fermi-level pinning is induced by the presence of silicon atoms at the HfO2 upper interface.