Etching Characteristics of HfAlO3 Thin Films Using an Cl2/BCl3/Ar Inductively Coupled Plasma

Abstract

In this study, we changed the etch parameters (gas mixing ratio, radio frequency [RF] power, direct current [DC]-bias voltage, and process pressure) and then monitored the effect on the HfAlO3 thin film etch rate and the selectivity with SiO2. A maximum etch rate of 108.7 nm/min was obtained in Cl2 (3 sccm)/BCl3 (4 sccm)/Ar (16 sccm) plasma. The etch selectivity of HfAlO3 to SiO2 reached 1.11. As the RF power and the DC-bias voltage increased, the etch rate of the HfAlO3 thin film increased. As the process pressure increased, the etch rate of the HfAlO3 thin films increased. The chemical state of the etched surfaces was investigated with X-ray photoelectron spectroscopy. According to the results, the etching of HfAlO3 thin film follows the ion-assisted chemical etching.