MEMS capacitive pressure sensor chip and manufacturing process thereof

Abstract

The invention discloses an MEMS capacitive pressure sensor chip. The MEMS capacitive pressure sensor chip comprises a first wafer and a second wafer, the first wafer comprises a first structure layer and a movable electrode layer which are bonded with each other, and the movable electrode layer forms a first closed ring, a reference capacitor plate and a movable capacitor plate which are physically and electrically isolated from each other through overall etching penetration. The top of the first structure layer is provided with a cavity, and the movable capacitor plate is located below the cavity. The second wafer comprises a fixed electrode layer and a second structure layer which are bonded with each other, and the fixed electrode layer forms a second closed ring and a fixed capacitor plate which are physically and electrically isolated from each other through integral etching penetration. The fixed electrode layer and the movable electrode layer are mutually bonded and connected. The invention further discloses a manufacturing process of the chip. According to the chip, the effect that the capacitor electrodes are isolated from external media is achieved, the differential capacitor design is adopted, and therefore the chip has the capacity of eliminating common-mode interference generated by factors such as the external temperature, humidity and the electromagnetic environment and has extremely high environmental adaptability.

Description

technical field [0001] The invention relates to the technical field of pressure sensors, in particular to a MEMS pressure sensor chip and a manufacturing process thereof. Background technique [0002] Compared with resistive, inductive and other sensors, capacitive pressure sensors have good temperature stability, simple structure, strong adaptability, good dynamic response, easy non-contact measurement and a certain average effect. Generally, inorganic materials are used as insulating supports. , so it can work in harsh environments such as high and low temperature, strong radiation and strong magnetic field, and can withstand large temperature changes, high pressure, high impact, and large overload. [0003] The main structural form of the current MEMS capacitive pressure sensor is to use two silicon-based capacitive plates, which are the movable plate and the fixed plate, and the movable plate is used as both the capacitive plate and the pressure-sensitive film. It is si...

AI Technical Summary

Problems solved by technology

First of all, the movable plate serves as both a capacitive plate and a pressure-sensitive film, and the electricity formed between the movable plate and the fixed plate is easily disturbed by the external environment, especially if the measured medium is a charged medium or a conductive medium, the coupling capacitance Interference is difficult to eliminate; secondly, in harsh environments, the movable plate of the sensor is directly in contact with the measured medium, which may easily lead to damage to the structure of the movable plate; finally, this structural design determines that the packaging form of the pressure chip is mostly Wire bonding, this packaging method greatly limits the media compatibility of the sensor, and it is difficult for the sensor to work in corrosive, conductive liquid or gaseous media

Therefore, it is difficult for existing technologies to overcome the problem of poor environmental adaptability of MEMS capacitive pressure sensors, and it is necessary to solve this problem from the perspective of design and production.

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