FINITE-ELEMENT MODELING AND CHARACTERIZATION OF A SILICON CONDENSER MICROPHONE WITH A HIGHLY PERFORATED BACKPLATE

A new method to simulate the sensitivity and frequency response of capacitive microphones has been developed. Finite-element analysis is used in combination with equivalent circuits to evaluate mechanical, electrostatic and acoustic effects. The simulation method has been applied to a condenser microphone in monocrystalline silicon. The design has a thin and highly perforated backplate in combination with a small air gap of 2 mum. Sensitivities in the range 1-5 mV/Pa have been recorded with a bias voltage between 5 and 13 V. The device has a first resonance at 27 kHz. The measured results are in good agreement with the results obtained with the new simulation method.