Abstract
In this study, we changed two input parameters (pressure vs. gas mixing ratio, RF power and DC bias voltage) and then monitored the effect on HfO 2 etch rate and selectivity with Si 3 N 4 and SiO 2 . When the pressure was fixed at 5 mTorr, etch rate of HfO 2 decreased with increasing Cl 2 content from 0 to 30% in BCl 3 /Ar plasma. At the conditions of 10 and 15 mTorr, the HfO 2 etch rate reached the maximum at 10% Cl 2 addition. As RF power and DC bias voltage increased in all ranges of pressure conditions, etch rates for HfO 2 showed increasing trends. The relative volume densities of radicals were monitored with optical emission spectroscopy (OES). The analysis of x-ray photoelectron spectroscopy (XPS) was carried out to investigate the chemical reactions between the surfaces of HfO 2 and etch species. Based on experimental data, the ion-assisted chemical etching was proposed as the main etch mechanism for the HfO 2 thin films in Cl 2 /BCl 3 /Ar plasma.
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