Inductively coupled plasma etching of SiO2 layers for planar lightwave circuits

We have systematically studied the etching characteristics of SiO 2 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 CF 4 or SF 6 was used as a reactive gas. Using either one of the gases, excellent results were obtained. Depths exceeding 6 μm were etched with few observable defects and near vertical sidewalls. This process was applied to make SiO 2 waveguides for planar lightwave circuits.