Etching of high-quality ZnO layers grown by molecular-beam epitaxy was examined by using electron-cyclotron-resonance plasma etching. Etching rates of ZnO layers were larger using CH4 than CF4, and four times more enhanced by using a mixture of the two gases. For a ZnO surface covered with photoresist layers by the plasma-etching procedure, degradation was mostly recovered by thermal annealing in an O-2 atmosphere at the proper temperatures. This was found to be effective for the recovery of the layers. (C) 2004 American Vacuum Society.