Effects of supercritical C O2 fluid on sputter-deposited hafnium oxide

Low-temperature supercritical fluid (SCF) technology is employed to improve the dielectric characteristics of metal oxide film deposited at low temperature. In this investigation, hafnium oxide (Hf O2) film was sputter deposited at room temperature and post-treated with SCF at 150 °C, replacing typical high-temperature annealing process. From Fourier transformation infrared and thermal desorption spectroscopy measurement, the absorption peaks of Hf-O-Hf bonding and the oxygen content in Hf O2 film have, respectively, shown apparent raise. The leakage current density of the low-temperature deposited Hf O2 film is reduced significantly, and the conduction mechanism is modified from trap-assisted quantum tunneling to thermionic emission process, since SCF treatment effectively reduces the number of traps in Hf O2 film.