CMOS compatible silicon differential condenser microphone and method for manufacturing the same

Abstract

A CMOS compatible silicon differential condenser microphone and a method for manufacturing the same are provided. The microphone(1000) comprises a silicon substrate(100), wherein a CMOS circuitry is accommodated thereon; a first rigid conductive perforated backplate(200) supported on the silicon substrate with an insulating layer(120) inserted therebetween; a second rigid perforated backplate(400) formed above the first backplate, including CMOS passivation layers(400a, 400c) and a metal layer(400b) sandwiched between the CMOS passivation layers as an electrode plate of the second plate, wherein an air gap, with a spacer forming its boundary, is provided between the opposite perforated areas of the first backplate and the second backplate; a compliant diaphragm(300) provided between the first backplate and the second backplate, wherein a back hole(150) is formed to be open in the silicon substrate underneath the first backplate so as to allow sound pass through, and the diaphragm and the first backplate form a first variable condenser, the diaphragm and the second backplate form a second variable condenser, and the first variable condenser and the second variable condenser form differential condensers.

Description

technical field

[0001] The invention relates to the technical field of microphones, in particular to a CMOS-compatible silicon differential capacitor microphone and a manufacturing method thereof. Background technique

[0002] Silicon-based MEMS microphones widely used in hearing aids, mobile phones, digital cameras and toys are reaching their limits. The need for smaller, cheaper, robust microphones with high sensitivity and low noise levels is endless. Reducing the size of a microphone degrades its performance, such as sensitivity. Today, however, micro-process technology provides very good control over the critical dimensions and characteristics of the microphone, enabling further miniaturization and optimization of the microphone. In addition, more complex MEMS microphone principles (such as a microphone with a differential capacitor and a differential preamplifier) ​​can be applied, so that the performance of the MEMS microphone (such as sensitivity) can be maintained...

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