The analysis of capacitive pressure sensors with large deflection

A set of analytical equations for the calculation of large deflection of square or rectangular boron-doped P/sup +/-Si diaphragms under pressure is obtained. Based on these equations and the mechanical properties of the Si thin diaphragm, such as the residual stresses, direct and shearing stresses, and Young´s modulus, a computer program using a personal computer was developed to calculate the deformation of the boron-doped P/sup +/-Si thin diaphragm, and the capacitance and sensitivity of a silicon capacitive sensor. A calculated curve for capacitive sensors with a thin silicon diaphragm agrees well with the measured results of those sensors. This simulation can be a simple but useful tool for the design of a large-deformation silicon capacitive pressure sensor.<>