Ni fully GermanoSilicide for gate electrode application in pMOSFETs with HfSiON gate dielectrics

A study on using a novel metal gate-the Ni fully GermanoSilicide (FUGESI)-in pMOSFETs is presented. Using HfSiON high-κ gate dielectrics and comparing to Ni fully Silicide (FUSI) devices, this paper demonstrates that the addition of Ge in poly-Si gate (with Ge/(Si+Ge)∼50%) results in: 1) an increase of the effective work function by ∼ 210 mV due to Fermi-level unpinning effect; 2) an improved channel interface; 3) a reduced gate leakage; and 4) the superior negative bias temperature instability characteristics. Low-frequency noise measurement reveals a decreased 1/f and generation-recombination noise in FUGESI devices compared to FUSI devices, which is attributed to the reduced oxygen vacancies (V_o)-related defects in the HfSiON dielectrics in FUGESI devices. The reduced V_o-related defects stemming from Ge at FUGESI /HfSiON interface are correlated with the Fermi-level unpinning effect and the improved electrical characteristics observed in FUGESI devices.