Inductively coupled plasma-reactive ion etching for β-FeSi 2 film

Abstract

A reactive ion etching technique for a semiconducting iron disilicide, β-FeSi 2, was successfully developed using CH 4/O 2/NH 3/CHF 3 discharge. A CH 4/O 2/NH 3 gas which is a sufficient reactant gas for materials including Fe did not etch the β-FeSi 2 film, and neither did SF 6/O 2 gas, which is widely used for Si etching. However, etching is promoted successfully by the addition of a CHF 3 gas into a CH 4/O 2/NH 3 gas and the surface flatness of β-FeSi 2 film was improved by exposing to the CH 4/O 2/NH 3/CHF 3 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 CH 4/O 2/NH 3/CHF 3 discharge was used to etch the entire β-FeSi 2 film such that the Si substrate emerged.