Dry Etching of High-k Dielectric Thin Films in HBr/Ar Plasma

High-k thin films (HfO2 and Al2O3) were etched in HBr/Ar high-density plasma. HfO2 and Al2O3 with high dielectric constants are promising candidates for the gates of metal-oxide-semiconductor devices. The maximum etch rates for HfO2 and Al2O3 were 49.1 nm/min and 42.5 nm/min, respectively. The etch rates of both HfO2 and Al2O3 thin films were faster for higher contents of HBr. The chemical states of high-k thin films were investigated using X-ray photoelectron spectroscopy. The comparisons of the as-deposited and the etched thin films for Hf 4f I Al 2p and O 1s showed few changes in the peak shapes and their binding energies were moved to higher energy after exposure to a HBr plasma. No new peaks due to etching byproducts appeared. Clean side wall and the steep etch profiles for high-k thin films could be obtained using a 100% HBr plasma. These results indicate that HfO2 and Al2O3 thin films can be effectively removed by using a chemical etching process.