Chemical dry etching of silicon oxide in F_2/Ar remote plasmas

摘要

In this study, we carried out chemical dry etching of silicon oxide layers by F_2/Ar remote plasmas generated from a toroidal-type remote plasma source. Chemical dry etching experiments were performed by varying the F_2 gas flow rate, F_2/(F_2+Ar) flow ratio, and substrate temperature. Under the current experimental condition, the chemical etching rates were significantly enhanced with increasing the F_2 gas flow rate and F_2/(F_2+Ar) flow ratio. Observed tendency in the etch rate was consistent with the variations of the optical emission intensity of the F radicals in the afterglow region of the remote plasma source and of the concentration of the emitted SiF_4 reaction by-products in the exhaust. The substrate temperature was the most influential process parameter in determining the chemical etching rates. Increasing the substrate temperature enhanced the etching rate by a factor of 2.9 ～ 4.4 depending on the F_2/(F_2+Ar) flow ratio.