Temperature Dependence on Dry Etching of Hafnium Oxide Using an Inductively Coupled Plasma

Abstract

We investigated the dependence of the etch rate of HfO2 thin films and selectivity of HfO2 over SiO2 in inductively coupled plasma on the substrate temperature in the range from 10 degrees C to 80 degrees C. The additional etch parameters examined were the amount of Cl2 added to BCl3/Ar (at a fixed gas mixing ratio of 4 sccm/16 sccm), RF power, DC-bias voltage and process pressure. The maximum etch rate of 125 nm/min was obtained at Cl2/BCl3/Ar = 2 sccm/4 sccm/16 sccm, an RF power of 600 W, DC-bias voltage of -200V, process pressure of 15 mTorr and substrate temperature of 80 degrees C. The selectivity of HfO2 over SiO2 was 0.79. The analysis by X-ray photoelectron spectroscopy explained the etching mechanism based on the physical and chemical pathways in the ion-assisted physical reaction.