A piezoresistive microcantilever array for surface stress measurement: curvature model and fabrication

Abstract

This paper presents a procedure for the fabrication of a piezoresistive microcantilever array for surface-stress-based chemical and biochemical sensing applications. All existing microcantilever surface stress sensors that are based on single-crystal silicon use p-doped piezoresistors. In this work, the advantages of using n-doped silicon piezoresistors for surface stress sensing have been demonstrated. Further, a new model for surface-stress-sensitive cantilevers, based on classical laminated plate theory, is presented. This model allows for the estimation of the deformation and piezoresistive response of a multilayered microcantilever to surface stresses during analyte measurement and residual stresses in the structural layers due to fabrication processes. Also, the model accounts for bending–stretching coupling in the microcantilever response to the stresses. The utility of the model as a design tool for control of cantilever curvature during the fabrication process has been demonstrated.