Silicon microphone development and application

This paper gives an overview of the development of Silicon microphones fabricated in a standard BiCMOS process line of Infineon. MEMS development results in reliable processes for high sensitivity poly-silicon membranes. Microphones with sensitivity up to −39 dB V/Pa at 2 V bias and a signal to noise ratio of up to 65 dB(A) are presented. The impact of packaging on the product design is described. As an example a directional microphone with cardioid response and backward noise suppression of 19 dB is described.