A reactive ion etching technique for a semiconducting iron disilicide, beta-FeSi2, was successfully developed using CH4/O-2/NH3/CHF3 discharge. A CH4/O-2/NH3 gas which is a sufficient reactant gas for materials including Fe did not etch the beta-FeSi2 film, and neither did SF6/O-2 gas, which is widely used for Si etching. However, etching is promoted successfully by the addition of a CHF3 gas into a CH4/O-2/NH3 gas and the surface flatness of beta-FeSi2 film was improved by exposing to the CH4/O-2/NH3/CHF3 discharge. The flattening is implicated in the anisotropic chemical reaction in the present etching process. In addition, almost no further etching of the bottom Si substrate was observed, when the present RIE process using CH4/O-2/NH3/CHF3 discharge was used to etch the entire beta-FeSi2 film such that the Si substrate emerged. (c) 2007 Elsevier B.V. All rights reserved.