A mems capacitive pressure sensor chip and its manufacturing process

Abstract

The invention discloses a MEMS capacitive pressure sensor chip, which includes a first wafer and a second wafer. The first wafer includes a first structural layer and a movable electrode layer bonded to each other, and the movable electrode layer penetrates through the overall etching to form a first closed ring physically and electrically isolated from each other, a reference capacitor plate and a movable capacitor plate . A concave cavity is opened on the top of the first structure layer, and the movable capacitor plate is located under the cavity; the second wafer includes a fixed electrode layer and a second structure layer bonded to each other, and the fixed electrode layer penetrates through the whole to form a mutual physical Electrically isolated second closed loop and fixed capacitor plate. The fixed electrode layer and the movable electrode layer are bonded and connected to each other. The invention also discloses the manufacturing process of the chip. The chip of the present invention achieves the effect of isolating the capacitive electrode from the external medium, and adopts a differential capacitance design, so that the chip has the ability to eliminate common-mode interference caused by factors such as external temperature, humidity, and electromagnetic environment, and has strong 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.

Images