Computer aided modelling and diaphragm design approach for high sensitivity silicon-on-insulator pressure sensors

Silicon on insulator (SOI) pressure sensor diaphragm is a composite structure of the buried oxide and the SOI layer. This paper brings out the inadequacy of the existing analytical model in describing the deflection response of SOI square diaphragms and focuses on the computer aided burst pressure incorporated high sensitivity design approach using IntelliSuite for SOI pressure sensors. The simulation results indicate that the maximum sensitivity is achieved at a side length of 800 μm for burst pressures of 10 and 5 MPa and at 900 μm for burst pressure of 2 MPa. The new modified analytical model developed and presented in this paper for describing the load–deflection performance of SOI composite diaphragm is able to predict the deflection accurately when compared with deflection obtained by IntelliSuite FEA thus illustrating the validity of the computer aided design approach. Further the new model has demonstrated that the existing analytical model overestimates the deflection and hence inadequate for application to SOI pressure sensors. The subsequent piezoresistive analysis carried out on these SOI sensors also confirms these findings and the maximum sensitivity that can be achieved is estimated to be 56 mV/MPa/V for the burst pressure of 5 MPa. The experimental results reported in the literature have been compared with the simulation results to validate the design approach presented in this paper.