Characterization and model validation of a micromechanical resonant magnetic field sensor

Abstract

This paper presents an analysis and model verification of a silicon-on-insulator (SOI) micromechanical resonant magnetic field sensor. The sensing mechanism is based on the detection of resonant frequency shift due to a Lorentz force that is generated by the presence of a magnetic field. We analyze the effect of scaling on sensitivity, showing that sensitivity improves when the device is thinner. The measured sensitivity is 677ppm/T with an associated high quality factor of 37000 when the thickness of the device is 10μm. Calibration slopes of the sensitivity measured from devices of different thicknesses all agree well with our analytical model predictions. Based on the model, we envisage that sensitivity could be further improved to about 1.7%/T within fabrication technology limitations.