Reactive ion etching of InP for optoelectronic device applications: Comparison in CH4, CH4/H-2, and CH4/Ar gas

The etching characteristics of InP using reactive ion etching in CH4 gas wi th/without Ha (or Ar) as diluents were compared. Etching parameters, such a s the CH4 flow rate, the H-2 (or Ar) flow rate, the RF power, and the proce ss pressure, were varied. The etch rates were measured by using a surface p rofiler. The etched profiles, sidewall roughness, and surface morphology we re observed from scanning electron microscopy and atomic force microscopy m easurements. The composition and the stoichiometry of etched surfaces were examined by both Auger electron spectroscopy and X-ray photoelectron spectr oscopy. The results suggest that a CH4 (10 sccm)/H-2 (40 sccm) gas mixture is the most promising for achieving ideal etching profiles in terms of surf ace roughness and anisotropy, which are suitable for fabricating of optoele ctronic devices. Optical waveguides and 1 x N multimode interference power splitters with a weakly guided ridge waveguide structure on InGaAsP/InP mat erials were fabricated by using the optimized CH4/H-2 RIE process.