High Mobility Ge pMOSFETs with ZrO2 Dielectric: Impacts of Post Annealing

This paper investigates the impacts of post metal annealing (PMA) and post deposition annealing (PDA) on the electrical performance of Ge p-type metal-oxide-semiconductor field-effect transistors (pMOSFETs) with ZrO 2 dielectric. For the transistors without PDA, on-state current ( I ON ), subthreshold swing (SS), and capacitance equivalent thickness (CET) characteristics are improved with PMA temperature increasing from 350 to 500 °C. Crystallization of ZrO 2 dielectric at the higher PMA temperature contributes to the increase of the permittivity of ZrO 2 and the decrease of the density of interface states ( D it ), resulting in a reduced CET and high effective hole mobility ( μ eff ). It is demonstrated that Ge pMOSFETs with a PDA treatment at 400 °C have a lower CET and a steeper SS but a lower μ eff compared to devices without PDA.