Parametric reactive ion etching of InP using Cl₂ and CH₄ gases: Effects of H₂ and Ar addition

The etching characteristics of InP by reactive ion etching (RIE) using Cl₂ and CH₄ gases were investigated systematically as functions of various etching parameters. The etching parameters, such as Cl₂ flow rate, CH₄ flow rate, rf power and process pressure, were varied. The effects of H₂ or Ar addition to the Cl₂ and the CH₄ discharges were compared. The etch rates of SiO₂ mask during Cl₂ RIE process were also measured. The etched profiles, sidewall roughness and surface morphology were observed by scanning electron microscopy and by atomic force microscopy. Auger electron spectroscopy was used to examine the elemental composition of etched surfaces and to evaluate contamination. The possible mechanism for these etching phenomena is discussed. The results suggest that a CH₄/H₂ gas mixture is the most promising for achieving ideal etching profiles (i.e., anisotropy, good surface morphology, smooth sidewall roughness) for optoelectronic device applications.