Three-dimensional micromachining of silicon using a nuclear microprobe

Abstract

We describe a novel technique for silicon microfabrication based on energetic mega-electron-volt (MeV) helium irradiation and subsequent electrochemical etching. The ion-induced damage in the irradiated regions slows down the porous silicon formation during electrochemical etching, producing a raised microstructure after cleaning in diluted potassium hydroxide solution. The thickness of the porous silicon layer formed depends on the accumulated fluence at each scan point. A relationship between the irradiated fluence and feature height is investigated on a p-type [100] silicon with a resistivity of 0.03 Ωcm using focused 2 MeV helium beam. We use this relationship to micromachine multilevel structures with a single focused helium beam energy. © 2004 Elsevier B.V. All rights reserved.