Etching of GaAs/AlGaAs rib waveguide structures using BCl3/Cl2/N2/Ar electron cyclotron resonance

An anisotropic nonselective etch for GaAs/AlGaAs rib waveguides has been developed for use under electron cyclotron resonance conditions. The plasma chemistry features BCl3 to minimize AlGaAs oxidation effects and small additions of N2 to induce sidewall protection when using photoresist masks. The fundamental mode attenuation in GaAs/AlGaAs waveguides is sensitive to the choice of both plasma chemistry and masking material, but can be reduced to ≤1 dB cm−1 for channel widths of 4–5 μm.