Characteristics of HfLaON/SiO 2 Gate Stack prepared using Reactive Sputtering

Abstract

HfLaON is one of the most promising high-k dielectrics because of its higher crystallization temperature and ability to tune the work function of the metal gates from Si midgap to around 4eV, meeting the requirement of nMOSFETs. In this paper, HfLaON was prepared using reactive sputtering that alternates between Hf and HfLa targets in N 2 /Ar ambient, followed by a post-deposition anneal. Before deposition of HfLaON film, SiO 2 interfacial layer was grown to improve the interface properties. HfLaON/SiO 2 gate stack exhibited good physical and electrical characteristics, including good thermal stability, excellent interface properties, small equivalent oxide thickness and low gate-leakage current. Further studies found that the excellent characteristics of the gate stack have close relation to the grown method of SiO 2 interfacial layer. In order to investigate their relationship, the different grown methods of SiO 2 interfacial layer were adopted and compared in the fabrication of HfLaON/SiO 2 gate stacks, such as oxidation in O 3 /H 2 O solution, rapid thermal anneal in N 2 or N 2 /O 2 mixed gas