ICP etching of InP and its applications in photonic circuits

Ridge waveguides with smooth and vertical sidewalls are essential in photonic circuits. We have investigated waveguide realization with reactive ion etching of InP and InP-based structures using a SiNx in a Cl2/H2/CH4 chemistry in an ICP plasma. Depending on ICP power and RF power, etching rates can be obtained from 200 nm/min up to > 2μm/min. A maximum etching selectivity of InP vs SiNx of 12 was obtained at 2000 W of ICP power. Deep etched waveguides, fabricated in an InP/InGaAsP double heterostructure, show typical losses of 2 dB/cm. This low value shows the potential of ICP technique in the fabrication of photonic circuits.