Method for processing micro-electromechanical systems (MEMS) sensor

Abstract

The invention provides a method for processing a micro-electromechanical systems (MEMS) sensor. The method comprises the following steps: providing a silicon substrate, and sequentially forming an etching barrier layer and a first electrode layer on the positive and reverse sides of the silicon substrate; patterning the first electrode layer on the positive side of the substrate; respectively and sequentially forming a sacrificial layer and a second electrode layer on the substrate; patterning the second electrode layer on the positive side of the substrate; etching the sacrificial layer to form a contact hole through the patterned second electrode layer, and respectively forming metal contact at the bottom of the contact hole and the second electrode layer; sequentially etching the second electrode layer, the sacrificial layer, the first electrode layer and the etching barrier layer from the reverse side of the substrate, continuously etching the substrate so as to reach the etching barrier layer on the positive side and stopping, and forming a deep groove with a downward opening; coating photoresist above the front side of the substrate to protect, and reserving a subsequent area in which the sacrificial layer needs to be etched; and etching the sacrificial layer through the patterned second electrode layer, and removing the etching barrier layer at the bottom of the deep groove. According to the method, the process steps are simplified, a smooth flow is guaranteed, and high yield is realized.

Description

technical field [0001] The invention relates to the technical field of micro-electromechanical systems (MEMS) manufacturing, in particular, the invention relates to a method for processing MEMS sensors. Background technique [0002] The MEMS microphones currently on the market are usually condenser microphones, the main structure of which is a movable membrane and an almost motionless backplane. The two electrodes forming the capacitor may be polycrystalline silicon, single crystal silicon, a composite layer of polycrystalline silicon plus silicon nitride, a composite layer of silicon nitride and metal, and the like. When the sound pressure acts on the film, the film will be displaced in different degrees according to the intensity of the sound pressure, which will cause the change of the capacitance, and the corresponding output voltage will change, and the corresponding sound signal can be read out through the amplifying circuit. [0003] MEMS microphones are usually prod...

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Problems solved by technology

[0004] The film or backplane of the MEMS microphone usually chooses one of the following three: 1. Composite layer, the process is relatively complicated and the control is difficult; 2. Single-layer polysilicon, the polysilicon film is usually deposited undoped polysilicon first, Then implant or diffuse it to form a doped conductor; 3. Single crystal silicon, which needs to be bonded with SOI silicon wafers or silicon wafers, which is very expensive

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