Geometry dependent sensitivity of planar piezoresistive stress sensors based on the pseudo-Hall effect

This paper reports a systematic analysis of the geometry dependent sensitivity of planar piezoresistive stress sensors based on the shear piezoresistance effect, also termed pseudo-Hall effect. The analyzed geometry parameters are: (i) the shape of the device active area, (ii) its aspect ratio, and (iii) the location and size of input and output contacts. Further, the influence of insulating holes in the active device area was investigated. General design rules for the design of piezoresistive stress sensors with improved sensitivity were extracted. These results were obtained using a simulation approach combining affine mapping with the finite element method. The simulation program was tested by comparing simulation results with experimental data. The differences between simulated and measured results were between 1.2% and 3.3%. Novel optimized sensor geometries with insulating holes show simulated and measured sensitivities greatly improved by factors up to 2.30 and 2.39, respectively.