A higher-k tetragonal HfO2 formed by chlorine plasma treatment at interfacial layer for metal-oxide-semiconductor devices

Abstract

A tetragonal HfO2 (t-HfO2) with higher-k value and large band gap is investigated in this work. X-ray diffraction analysis shows a t-HfO2 can be formed by using Cl2 plasma treatment at the HfO2/Si interface after a post deposition annealing at 650 °C. The mechanisms of t-HfO2 formation can be attributed to the Si diffusion and oxygen vacancy generation which are formed by Cl2 plasma treatment. From the cross-sectional transmission electron microscope and capacitance-voltage measurement, the k value of this t-HfO2 is estimated to be about 35. The optical band gap value for t-HfO2 is similar to that of the monoclinic.