Fabrication of high-aspect-ratio InP-based vertical-cavity laser mirrors using CH4/H2/O2/Ar reactive ion etching

The addition of oxygen to methane/hydrogen/argon reactive ion etching (RIE) processes mitigate polymer deposition, and produce vertical etched sidewalls, This work contrasts the various ways in which the oxygen may be incorporated into methane/hydrogen/argon reactive ion etching of deep(>5 mu m) InGaAsP/InP multilayers. Three methods are investigated: a "continuous" process in which a fixed amount of oxygen is added to methane/hydrogen/argon for the duration of the etch, a "cyclical" process in which the methane/hydrogen/argon RIE processes alternates with oxygen RIE, and a hybrid process which incorporates the advantages of both former methods. These processes are applied to the fabrication of tall (>10 mu m) InGaAsP/InP quarter-wave mirrors for long-wavelength vertical-cavity lasers; the various benefits and limitations of the various approaches are discussed. It is found that the hybrid process allows formation of deeply etched structures (15 mu m) with vertical profiles. (C) 1997 American Vacuum Society.