Focused ion beam milling and deposition techniques in validation of mass change value and position determination method for micro and nanomechanical sensors

Abstract

In this paper, we apply the focused ion beam technique (FIB) to add and subtract material from a microcantilever sensor and use a non-uniform mass sensitivity model to determine the position and value of mass load. We add and remove a defined amount of mass from the cantilevers at specified positions by FIB assisted deposition and milling, thus we introduce non-uniform mass load. Utilizing intrinsic thermal noise of the cantilevers, we measure the frequencies of multiple modes of flexural vibrations in ambient air before and after FIB processing. By application of a theoretical mass sensitivity model, we are able to determine both, the amount of added or removed mass and its position along the cantilever length. The results obtained from the model are in good agreement with estimations based on scanning electron microscopy and FIB observations.