Application of He’s variational iteration method to the estimation of diaphragm deflection in MEMS capacitive microphone

In this paper, He’s variational iteration method (VIM) is used to analyze the deflection of poly silicon diaphragm of Micro Electro Mechanical Systems (MEMS) capacitive microphone. The residual stresses in the material used to make the diaphragm change the vibrational characteristics of the microphone diaphragm and consequently influence the microphone’s first resonant frequency, cutoff frequency and sensitivity. The most successful devices use poly silicon as a diaphragm material, because of its residual stress is controllable by high-temperature annealing after ion implantation by boron or phosphorous. External acoustic force causes to deflect the diaphragm of the structure and VIM is a powerful analytical method to predict the structural behavior and the microphone performance. Comparison of this new method with the previous approximate solution [1], is applied to assure us about the accuracy of solution.