Fast etching of copper in thionyl chloride/acetonitrile solutions

We report fast etching of copper (Cu) in thionyl chloride (SOCl(2))/acetonitrile (CH(3)CN) solutions. The etching rate can be tuned over a wide range by varying the concentration of the etchant, and the stirring rate of the liquid. The etching rate reaches 36 mg min(-1) cm(-2) in 1 mol L(-1) SOCl(2)/CH(3)CN under stirring at room temperature, which is much faster than any currently used etchant for Cu. With sonication, the etching rate reaches 320 mg min(-1) cm(-2). The chemical reactions involved are studied by X-ray photoelectron spectroscopy and Raman spectroscopy. The fast etching may find important applications in microelectronics. Published by Elsevier Ltd.