Characterization of heavy deposits on InP mesa sidewalls reactive ion etched using CH4/H-2 plasma

The formation of heavy deposits on the top part of mesa sidewalls has been studied in detail, during the CH4/H-2 reactive ion etching of InP using SiO 2, Ti/Au, Ti/W and Ti/Cr masks. X-ray microanalysis in transmission electro n microscopy showed that the deposits were In-Si-P oxide with more In than P, regardless of the mask material utilized. The deposits were found to for m when etched using Ti/Au etch masks or etched at high CH4 concentration an d low RF power using SiO2 masks. No such deposits were observed in the case of Ti/W and Ti/Cr masks, implying that these metals may be used for the se lf-aligned etch mask.