Recovery of plasma-induced mechanical damage in resonators using Neutral Beam Etching: Wafer-scale validation by arrayed cantilevers

Abstract

As an effective application of Neutral Beam Etching (NBE) to MEMS, we here propose a combined approach with conventional plasma process and NBE: removal of plasma-induced damage by NBE. If it is possible, we can obtain a damage-free surface for MEMS devices without a high-temperature annealing process. In order to evaluate the effect of this combined approach quantitatively; we focused on the resonance of a micro cantilever and derived a parameter of surface damage (δE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ds</sub> ) theoretically from Q-factor and resonance frequency. And then we examined the change in δE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ds</sub> of the cantilevers on an 8-inch wafer before and after NBE treatment. The initial surface of cantilevers had been damaged by plasma processes during their fabrication, and the removal of those damage by NBE was confirmed as the reduction in δE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ds</sub> .