Low-damage silicon etching using a neutral beam

Abstract

A low-damage silicon etching technology for fabricating microelectromechanical system (MEMS) devices using a neutral beam is reported. Neutral beams were produced from Cl2 plasma in an etching apparatus and were used to etch silicon trenches and MEMS devices. Si trench etch rate depended on the bias voltage applied to an aperture, used to produce the neutral beam. Etch rate decreased with increasing Si trench aspect ratio. This trend was minimized by enlarging the aspect ratio of through-holes in the aperture. The silicon trench profile was influenced by the aspect ratio of through-holes in the aperture. Etched Si surfaces were smooth, and no damage/defects were observed by transmission electron microscopy. Si etching of MEMS devices with smooth surfaces and scallop free sidewalls was achieved. The mechanical characteristics of an oscillator etched with the neutral beam were superior to those of that etched using a conventional Bosch process.