Dual‐backplate capacitive aeroacoustic microphone

Abstract

High‐performance instrumentation grade microphones are a crucial component for aeroacoustic measurements. This paper presents the design, fabrication, and characterization of a MEMS dual‐backplate capacitive microphone designed for aeroacoustic applications where small size, high dynamic range, and high bandwidth are key requirements. The microphone features a 230‐micron radius, 2‐micron air gaps, and a 118‐dB dynamic range. Experimental results indicate a sensitivity of 0.282 mV/Pa, a linear response up to 160 dB, a noise floor of 42 dB at 1 kHz in a 1‐Hz bin, and a measured resonant frequency of 230 kHz. A flat frequency response was measured up to 20 kHz in an 8.5×8.5−mm square rigid‐walled acoustic plane‐wave tube. The microphone was designed using an equivalent lumped‐element model, simulated using finite‐element methods, and fabricated using the SUMMiT V process at Sandia National Laboratories. Details on the acoustic and electrical characterization, fabrication process, and packaging will be described in the presentation.