The etching of GaAs materials under electron cyclotron resonance conditions has been performed in an ECR etching system with rf biasing usinia the CCl2F2/Ar/O-2 plasma chemistry. Etching experiments were carried out at a pressure between 0.015 and 0.020 mbar, rf power 0.39 W/cm(2). and dc bias voltage 200 V. The surface morphology and etch depth were taken by scanning electron microscopy and Dektek Profilometry respectively. The use of ECR conditions with additional rf biasing provides the good etching of the surface and fast etch rates. Moreover, the surface of the GaAs material display smooth and stoichiometric surfaces at higher ECR powers. The surface damages on the GaAs samples after the plasma exposure have been studied using IR spectroscopy. (c) 2004 Elsevier B.V. All rights reserved.