Capacitance type microphone with stress release membrane prepared at a low temperature and preparation method thereof

Abstract

A capacitance type microphone with a stress release membrane prepared at a low temperature and a preparation method thereof. The capacitance type microphone includes a substrate having at least a resonant cavity; a septum, arranged on the top of the resonant cavity and connected with the substrate for implementing a mechanical vibration when being excitated by an acoustic pressure wave; a back board, arranged on the top of the septum and having a plurality of perforations; an air gap is provided the back board and the septum; a capacitor is composed of the septum, the air gap and the back board. The method includes steps: forming the resonant cavity on the substrate; forming the septum on the top of the resonant cavity, wherein the septum is connected with the substrate; setting the back board on the top of the septum, wherein the back board has a plurality of perforations; forming the air gap between the back board and the septum. The invention is a MEMS capacitance type microphone processed by a completely low-temperature technique. It is capable of being used as a post IC circuit processing technique being compatible thereof. The structure of the vibration diaphragm of the capacitance type microphone is a stress-releasing structure, and is capable of reducing a parasitic capacitance. Comparing with the traditional initial stress release membrane, the invention improves the sensitivity of the microphone more effectively.

Description

【Technical field】 [0001] The invention relates to a condenser microphone and a manufacturing method thereof. A condenser microphone includes a diaphragm with electrodes disposed on a substrate having at least one resonant cavity, and a counter-electrode backplate on the diaphragm. There is an air gap between the diaphragm and the backplate; the electrodes are connected to the backplate through a plurality of stress relief structures. The materials of the diaphragm and backsheet are selected to avoid sticking during processing and use. Between the backplane and the substrate support is a thicker dielectric layer. The manufacturing process of the whole device is carried out at a temperature not exceeding 300°C. 【Background technique】 [0002] The pressure-sensing membrane of a typical condenser microphone uses a low-stress silicon nitride or single-crystal silicon thin film. Although the micro-processing of these sensing films is relatively mature, this traditional sensing...

AI Technical Summary

Problems solved by technology

Although the micro-processing of these sensing films is relatively mature, this traditional sensing film has the following disadvantages: (1) The forming process temperature of the film is relatively high, and it is difficult to integrate with related signal processing chips

(2) The large residual stress of the vibrating film leads to a relatively large size of the device, which is not easy for system integration

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