Influence of O_2/Ar flow ratio on HfO_2 thin films prepared by RF magnetron sputtering

HfO2 thin films were deposited on quartz substrate by RF magnetron sputtering with HfO2 ceramic target.The influence of O2/Ar flow ratio on the deposition rate,structure and morphology of HfO2 thin films were investigated by spectroscopic ellipsometry(SE),X-ray diffraction(XRD) and field emission scanning electron microscopy(FE-SEM).The results showed that the deposition rate decreases with the increasing O2/Ar flow ratios from 0 to 0.50.When the O2/Ar flow ratio is 0,the prepared film grows towards preferred orientation with high crystallinity,large grain size and columnar crystal.Meanwhile,after oxygen is introduced into the deposition,the thin films prepared have random orientation with low crystallinity,small grain size and granular morphology.When the O2/Ar flow ratio increases from 0.25 to 0.50,the grain size increases but the morphology of the thin films changes little.At last,the preferred orientation growth mechanism of HfO2 thin film was discussed.