Inductively coupled plasma etching of SiO2 layers for planar lightwave circuits

We have systematically studied the etching characteristics of SiO2 layers using an inductively coupled plasma (ICP) etching system. The surface morphology, etch rate, selectivity, and sidewall angle have been studied as a function of varying pressure, gas flow rate, capacitive r.f. power, and inductive r.f. power. Chrome was used as an etch mask, and CF4 or SF6 was used as a reactive gas. Using either one of the gases, excellent results were obtained. Depths exceeding 6 mu m were etched with few observable defects and near vertical sidewalls. This process was applied to make SiO2 waveguides for planar lightwave circuits. (C) 1999 Published by Elsevier Science S.A. All rights reserved.