Fully silicided NiSi gate electrodes on HNON gate dielectrics for low-power applications

The fully silicided (FUSI)-nickel monosilicide (NiSi) metal gate electrode on the HfSiON gate dielectric has been investigated for low-power metal-oxide-semiconductor field effect transistors (MOSFETs). We found that the FUSI-NiSi electrode oil the HfSiON dielectric has a work function of 4.55 eV, which improved the threshold voltage shift of PMOSFETs by 0.15 V compared with that of the poly-Si/HfSiON MOSFETs. At the same time, full silicidation eliminated the gate depletion and thereby we achieved the capacitance equivalent thickness at inversion of 2.1 nm and a five-order-of-magnitude reduction in the gate leakage current compared with the poly-Si/SiO2 devices. Moreover, we obtained an excellent carrier mobility for the FUSI-NiSi/HfSiON transistors (PMOS: 100%, NMOS: 90% compared with the poly-Si/SiO2 reference transistors). These results show that the FUSI-NiSi/HfSiON gate stack is a promising candidate for next-generation low-power MOSFETs.