A new gate dielectric HfLaO with metal gate work function tuning capability and superior NMOSFETs performance

Abstract

Using a novel HfLaO gate dielectric for MOSFETs, we report for the first time that TaN (or HfN) metal gate work function can be effectively tuned from Si mid-gap to the conduction band by increasing La composition to fit the requirement of NMOSFETs. We also show the superior performance of the NMOSFETs compared with those using pure HfO2 gate dielectric: (1) dielectric crystallization temperature raised to 900 °C, (2) 60-70% enhancement of drive current Ion and electron mobility, (3) one order reduction of dielectric charge trapping and BTI, and (4) around 5 orders reduction of gate current compared with SiO2 at the same EOT of 1.2-1.8 nm. © 2005 IEEE.