Reactive Ion Etching of β-FeSi2 with Inductively Coupled Plasma

Abstract

A dry etching technique for a β-FeSi2 film on Si(111) was successfully developed. The technique is reactive ion etching (RIE) with inductively coupled plasma using CH4/O2/NH3/CHF3 discharge at a low pressure. It was found that CHF3 gas is indispensable in this etching technique, since CH4/O2/NH3 did not etch the film, and neither did SF6/O2, which is widely used for Si etching. Almost no further etching of the bottom Si substrate was observed and a carbon residual appeared on the surface, when the present RIE process using CH4/O2/NH3/CHF3 discharge was used to etch the entire β-FeSi2 film such that the Si substrate emerged. This experimental result shows a possibility of highly selective RIE for β-FeSi2/Si heterostructures.