Surface and bulk micromachined dual back-plate condenser microphone

This paper presents the design, fabrication, and characterization of a dual back-plate condenser microphone. The microphone was designed for aeroacoustic applications where a high dynamic range and high bandwidth are key requirements. It was fabricated using the SUMMiT V process at Sandia National Laboratories. The microphone has a 2.25 /spl mu/m thick circular diaphragm with a 230 /spl mu/m radius and 2 /spl mu/m gap between each back-plate. The device has demonstrated a sensitivity of 282 /spl mu/V/Pa, a linear response up to 160 dB, a noise floor of 42 dB//spl radic/Hz at 1 kHz in a 1 Hz bin, and a flat frequency response up to 20 kHz; the theoretical bandwidth exceeds 100 kHz.