Sidewall and surface induced damage comparison between reactive ion etching and inductive plasma etching of InP using a CH4/H-2/O-2 gas mixture

We report the results of a comparative characterization between reactive ion etching and inductive coupled plasma (ICP) etching of InP with a CH4/H-2/O-2 gas mixture. Particular attention was paid to the surface morphology and to the pattern profiles that were observed by scanning electron microscopy. A comparison with morphology of patterns etched by argon ion milling is also included. Auger electron spectroscopy and secondary ion mass spectrometry were used to obtain the elemental composition in the top 30 nm of the etched surface and to evaluate pollution and stoichiometry. Transmission electron microscopy was used to observe the sidewall damage and to evaluate the effect of sidewall deposit. The respective roles of incident and reflected energetic species and deposits are identified. The effect of anisotropy on sidewall deposits was also observed. Finally, surface damage induced on InP etched substrates was characterized through photoluminescence intensity. The destructive effects of high ion energy etching processes on the samples was observed in terms of stoichiometry modification, surface contamination, and polycrystallization of sidewalls. Some very low energy processes were studied with the ICP equipment. An extremely low damage level could be obtained in such processes while keeping a sufficient etch rate. However, the low ion energy ICP etching processes are isotropic. (C) 1996 American Vacuum Society.