Low Frequency Response Microphone Diaphragm Structures And Methods For Producing The Same

摘要

A microphone system includes a diaphragm suspended by springs and including a sealing layer that seals passageways which, if left open, would degrade the microphone's frequency response by allowing air to pass from one side of the diaphragm to the other when the diaphragm is responding to an incident acoustic signal. In some embodiments, the sealing layer may include an equalization aperture to allow pressure to equalize on both sides of the diaphragm.

主权项

1. A method of fabricating a microphone having a sealing layer, comprising:
providing a substrate wafer having a surface; etching trenches into the surface of the substrate wafer; covering the surface of the substrate with a sacrificial material, the sacrificial material filling the trenches; depositing a seal layer on the sacrificial material, the seal layer having a thickness of not greater than 500 nanometers; etching a seal aperture in the seal layer; adding additional sacrificial material within the seal aperture such that the additional sacrificial material is contiguous with the sacrificial material; depositing a diaphragm layer on the seal layer; etching a spring gap and springs into the diaphragm layer to define a diaphragm region in the diaphragm layer; etching a backside cavity in the substrate wafer to expose the sacrificial material; and removing the sacrificial material and the added sacrificial material to release the diaphragm such that the diaphragm is suspended by the springs and is movable relative to the backplate, wherein diaphragm and backplate form a variable capacitor of a microphone, and the springs suspend the diaphragm when the microphone is in operation, and the seal layer seals the diaphragm region except at the location of the seal aperture.