HfO₂-TiO₂Ultra-Thin Gate Dielectric by RF Sputtering

Abstract

High-K HfO 2 -TiO 2 ultra-thin films with sub-nanometer laminate HfO 2 /TiO 2 stacks were deposited on p-type (100) silicon wafer using magnetron sputtering at 300 • C. The as-deposited films are amorphous which could be sustained up to 900 • C in air. The off-stoichiometric films show further improved thermal stability due to obstacled crystallization process. It is revealed that Hf-rich films trends to form thicker interfacial layer due to the stability of HfO 2 , whereas Ti-rich films usually demonstrate higher leakage current owing to the low band gap of TiO 2 . In this work, 20-nm-thick films with Hf/Ti ratio of 46/54 demonstrates higher permittivity up to 50 with low leakage current 1.2 × 10 −8 A/cm 2 at 1 V.