Investigation of etching properties of HfO based high-Kdielectrics using inductively coupled plasma

Abstract

The etching properties of HfO based high dielectric constant (K) films, HfO2, HfON, HfSiO, and HfAlO, were investigated using inductively coupled plasma of Cl2/HBr/CHF3/CF4/O2. The etch rates varied depending on the chemical components in the films. Among HfO2, HfON, HfSiO, and HfAlO, the etch rates of HfSiO increased most significantly with increasing radio frequency bias power. This may be attributed to the ternary network of Hf–Si–O that is different from the binary network of other films of Hf–O, Hf–N, Si–O, and Al–O. The etch rates of HfON were higher than those of HfO2 due to the effect of the high Hf–N etch rates compared to the Hf–O etch rates, whereas the HfAlO etch rates were lower than those of HfO2 due to the effect of the low Al–O etch rates. Etch residues and chemical compositions of HfO based dielectrics were analyzed by x-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectroscopy. A significant amount of fluorides existed on the surface after CF4/CHF3 etching whereas only a small amount of chloride and bromide existed after Cl2/HBr etching. The high temperature post-treatment step was effective in reducing the amount of residues.