Capacitor type microphone chip

Abstract

The invention discloses a capacitive microphones chip, which relates to a microphone technology. The capacitive structure is that a vibration film is at the upper part and a back electrode is at the lower part. The vibration film is supported by a plane compound suspension girder or a vertical suspension girder so that the stress is distributed uniformly when the vibration film vibrates. The connection between the vibration film and the back electrode can be effectively reduced and the yield rate also can be improved; the suspension girder structure is soft and the vibration film has a good vibration characteristic. Only the center part of the back electrode is suspended and the surrounding part thereof is covered on a substrate. The supporting of the substrate increases the rigidity of the back electrode; a stiffener can be arranged on the suspension part of the back electrode; therefore, the rigidity of the back electrode can be further improved. The edge of the vibration film is provided with numerous small holes which can release an initial sacrificial layer between the vibration film and the back electrode coordinating with acoustic holes on the suspension part in the back electrode, as well as have an improvement effect to the acoustic characteristics of the microphones. The capacitive microphones chip has the characteristics of high sensitivity, low noise, and wide frequency band. The chip has a small volume. The manufacturing process is simple and batch production is easy to be carried out.

Description

technical field [0001] The invention relates to the technical field of microphones, in particular to semiconductor capacitive microphone chips. Background technique [0002] The research on semiconductor microphone chips has a history of more than 20 years, during which various types of microphones have been developed and implemented on silicon chips. Among them, the most important and popular one is the condenser silicon microphone. Capacitive silicon microphones not only have the characteristics of small size, high sensitivity, good frequency response characteristics, and low noise, but more importantly, they have a wide operating temperature and are suitable for SMT and other automated production lines and harsh working environments. [0003] The condenser microphone chip is an acoustic sensor manufactured by micromachining technology, and its functional structure is a flat plate capacitor composed of a diaphragm and a back electrode. The diaphragm vibrates under the ac...

AI Technical Summary

Problems solved by technology

At present, the reported methods include: the patent US6012335 uses a thick gold layer as the back electrode; the patent US6677176B2 uses a composite metal film as the back electrode, which reduces the stress and increases the thickness; the US6140689 patent uses a single crystal silicon layer in the SOI silicon wafer as the back electrode ; US6667189B1 adopts electrochemical corrosion to make a low-stress thick monocrystalline silicon back electrode; US6532460B2 makes a special structure to increase the strength of the back electrode, most of which are complicated in process and high in production cost

[0006] After obtaining a soft diaphragm and a rigid back electrode, the problem of adhesion between the diaphragm and the back electrode must also be solved. So far, there are many methods. The more effective method is to make anti-adhesion protrusions, but it needs to increase the process steps and increase the cost.

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