A SILICON CONDENSER MICROPHONE WITH POLYIMIDE DIAPHRAGM AND BACKPLATE

A new technology for the fabrication of silicon condenser microphones is presented. The technology, which is based on the use of polyimide, can be performed entirely as a post process on substrates already cont aining integrated circuits. Microphones with an open-circuit sensitivi ty of 8.1 mV Pa-1, and a flat frequency response (+/-2 dB) between 100 Hz and 15 kHz have been fabricated with this technology. The bias vol tage used in these measurements is 15 V, and the measured noise level with zero bias is 24 dB SPL, which is sufficient for most acoustic app lications, including hearing aids. (C) 1997 Elsevier Science S.A.