A comparative study of HfTaON/SiO2 and HfON/SiO2 gate stacks with TaN metal gate for advanced CMOS applications

Abstract

The electrical characteristics of a novel HfTaON/SiO2 gate stack, which consists of a HfTaON film with a dielectric constant of 23 and a 10-Å SiO2 interfacial layer, have been investigated for advanced CMOS applications. The HfTaON/SiO2 gate stack provided much lower gate leakage current against SiO2, good interface properties, excellent transistor characteristics, and superior carrier mobility. Compared to HfON/SiO2, improved thermal stability was also observed in the HfTaON/SiO2 gate stack. Moreover, charge-trapping-induced threshold voltage Vth instability was examined for the HfTaON/ SiO2 and HfON/SiO2 gate stacks. The HfTaON/SiO2 gate stack exhibited significant suppression of the Vth instability compared to the HfON/SiO2, in particular, for nMOSFETs. The excellent performances observed in the HfTaON/SiO2 gate stack indicate that it has the potential to replace conventional SiO2 or SiON as gate dielectric for advanced CMOS applications.© 2007 IEEE.