Simulation of Perforated Diaphragms Employed Piezoresistive Pressure Sensor for Sensitivity Enhancement and Validation with Modified Analytical Model

Abstract

The details of a study on perforated diaphragms for pressure sensing in piezoresistive MEMS pressure sensors are presented in this paper. Both perforated and non-perforated diaphragms of different thicknesses have been considered to study and evaluate the performance of perforated diaphragms for pressure measurement in terms of load-deflection sensitivity, stress generation and load-voltage sensitivity. The IntelliSuite MEMS design tool has been used to create and analyze the pressure sensors with non-perforated and perforated silicon diaphragms. The results show that it is possible to achieve more than 80% improvement in deflection, 90% in voltage sensitivities and more than 135% improvement in stress generation with 40% perforated area irrespective of the thickness of the diaphragm. This leads to the conclusion that the perforation realized on thicker diaphragms are suitable alternatives with satisfactory performance to very thin non-perforated diaphragms and hence it can be employed to achieve the desired specifications. These simulation results have been validated by comparing the deflection response estimated with the modified load-deflection analytical model that is developed in this work by suitably modifying the bending rigidity of clamped square diaphragms taking the perforation into account.