Comparison of CH4/H-2 and C2H6/H-2 inductively coupled plasma etching of ZnO

摘要

CH4/H-2-based discharges are attractive for dry etching of single crystal ZnO because of their non-corrosive nature. We show that substitution of C2H6 for CH4 increases the ZnO etch rate by approximately a factor of 2 both with and without any inert gas additive. The C2H6/H-2/Ar mixture provides a strong enhancement over pure Ar sputtering, in sharp contrast to the case of CH4/H-2/Ar. The threshold ion energy for initiating etching is 42.4 eV for C2H6/H-2/Ar and 59.8 eV for CH4/H-2/Ar. The etched surface morphologies were smooth, independent of the chemistry and the Zn/O ratio in the near-surface region was unchanged within experimental error after etching with both chemistries. The plasma etching improved the band-edge photoluminescence intensity and suppressed the deep level emission from the bulk ZnO under our conditions, due possibly to removal of surface contamination layer. (c) 2006 Elsevier B.V. All rights reserved.