Process development of methane–hydrogen–argon-based deep dry etching of InP for high aspect-ratio structures with vertical facet-quality sidewalls

We examine methane–hydrogen–argon-based deep dry etching of InP for facet-quality sidewalls by reactive ion etching. A process is developed for etch depths as high as 5.8 μm. Masks studied include Ni, NiCr, Ti, SiO2, and Ti–SiO2. Sidewall roughness was estimated to be a few nm (based on high resolution scanning electron micrographs). This may be useful for fabrication of optical microelectromechanical systems, photonic wires, and photonic crystals in the InP material system.