A silicon condenser microphone with a highly perforated backplate

Condenser microphone chips in monocrystalline silicon have been designed and realized with a technology that is well adapted to batch fabrication. The novel design has a thin and highly perforated backplate in combination with an air-gap of 2 mu m. The device has a low bias voltage of 5 V, a frequency response within +or-3 dB from 2 Hz to 20 kHz, and sensitivities in the range of 1 to 2 mV/Pa. Simulations with equivalent acoustical circuits agree well with experimental data up to a frequency of 15 kHz.<
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