On accuracy of sensitivity relations for piezoresistive microcantilevers used in surface stress studies

Abstract

This work presents analytical models for predicting the surface stress-induced deflection and stress in silicon and CMOS piezoresistive microcantilevers. The models can be combined to determine the surface stress sensitivity of such microcantilevers when used for surface stress studies. The substrate of silicon cantilever is silicon and of CMOS is silicon dioxide. The cantilevers have a p-doped silicon piezoresistor. The piezoresistor size is varied to investigate its effect on the sensitivity under a surface stress of 1 N/m. The analytical results are compared against numerical ones obtained using a commercial finite element analysis software. The sensitivity results show good conformity between analytical and numerical predictions with the average deviation of about 4%.