Electron beam induced etching of silicon with SF6

Abstract

Electron beam induced etching (EBIE) with SF6 precursor molecules has been demonstrated as an approach to induce localized etching of Si with an etch yield of approximately 0.003 atoms/incoming electron. Further understanding of the EBIE mechanisms is presented through an analysis of the influence of the different electron beam parameters (beam energy and electron flux) and the effect of the sample bias on the EBIE rate. It is demonstrated that the etch rate increases with decreasing beam energy and with increasing electron flux to a saturation value. The latter is explained by a transition from an electron flux density limited process (at low current densities) to a gas supply limited process (at high current densities). The authors also demonstrate that a large etch rate enhancement is obtained by applying a positive sample bias. This is explained within the frame of a model outlining the role of the low secondary energy electrons in the electron stimulated etching process.