Differential microphone with sealed backside cavities and diaphragms coupled to a rocking structure thereby providing resistance to deflection under atmospheric pressure and providing a directional response to sound pressure

Abstract

A vacuum sealed directional microphone and methods for fabricating said vacuum sealed directional microphone. A vacuum sealed directional microphone includes a rocking structure coupled to two vacuum sealed diaphragms which are responsible for collecting incoming sound and deforming under sound pressure. The rocking structure's resistance to bending aids in reducing the deflection of each diaphragm under large atmospheric pressure. Furthermore, the rocking structure exhibits little resistance about its pivot thereby enabling it to freely rotate in response to small pressure gradients characteristic of sound. The backside cavities of such a device can be fabricated without the use of the deep reactive ion etch step thereby allowing such a microphone to be fabricated with a CMOS compatible process.