Optimization of reactive-ion etching (RIE) parameters for fabrication of tantalum pentoxide (Ta₂O₅) waveguide using Taguchi method

摘要

In this paper, we demonstrate the optimization of reactive-ion etching (RIE) parameters for the fabrication of tantalum pentoxide (Ta_(2)O_(5)) waveguide with chromium (Cr) hard mask in a commercial OIPT Plasmalab 80 RIE etcher. A design of experiment (DOE) using Taguchi method was implemented to find optimum RF power, mixture of CHF~(3) and Ar gas ratio, and chamber pressure for a high etch rate, good selectivity, and smooth waveguide sidewall. It was found that the optimized etch condition obtained in this work were RF power = 200 W, gas ratio = 80 %, and chamber pressure = 30 mTorr with an etch rate of 21.6 nm/min, Ta_(2)O_(5)/Cr selectivity ratio of 28, and smooth waveguide sidewall.