Low-temperature method for enhancing sputter-deposited HfO2 films with complete oxidization

Abstract

A low-temperature method, supercritical CO2 fluid (SCF) technology, is proposed to improve the dielectric properties of ultrathin hafnium oxide (HfO2) film at 150°C without significant formation of parasitic oxide at the interface between HfO2 and Si substrate. In this research, the HfO2 films were deposited by dc sputter at room temperature and post-treated by SCF which is mixed with 5vol% propyl alcohol and 5vol% H2O. From high-resolution transmission electron microscopy image, the interfacial oxide of SCF-treated HfO2 film is only 5Å thick. Additionally, the enhancements in the qualities of sputter-deposited HfO2 film after SCF process are exhibited by x-ray photoelectron spectroscopy and capacitance-voltage (C-V) measurement.