Controlled beam dry etching of InP by using Br2-N2 gas

When Indium phosphide dry etching is carried out using a reactive beam extracted from Br2-N2 mixture gas discharge plasma, two distinct types of etching mechanisms come into play as the Br2 gas pressure is changed. Smooth vertical side walls can be obtained at low Br2 gas pressure, where the etching rate has no temperature dependence, while undercutting with a temperature dependent etching rate is seen at high Br2 gas pressure. An analysis of the plasma discharge currents reveals that neutralized Br species generated by the discharge of Br2 gas itself form the undercut. A waveguide corner mirror with less than 1 dB loss can be made by using an etching beam with no neutralized Br species.