MEMS absolute pressure sensor and processing method thereof

Abstract

The invention provides an MEMS absolute pressure sensor and a processing method thereof. The sensor comprises a glass cover plate, a silicon pressure sensing film and a glass substrate. One side of the silicon pressure sensing film is in anodic bonding with the glass substrate to form two communicated vacuum reference cavities, the other side of the silicon pressure sensing film is in anodic bonding with the glass cover plate to form two independent open type gas pressure sensing structures, and the two communicated vacuum reference cavities correspond to the two independent open type gas pressure sensing structures up and down, and form a series mutual inductance double-capacitor structure with a silicon pressure sensing film, and a lead electrode is processed on the silicon pressure sensing film and used for leading out an air pressure detection signal. External air pressure is applied to the silicon pressure sensing film through the open type gas pressure sensing structure, pressure difference is formed between the external air pressure and the vacuum reference cavity to enable the silicon pressure sensing film to deform, then the distance between the silicon pressure sensing film and the capacitance plate of the glass substrate is changed, and the capacitance value is changed to reflect the external air pressure. The processing technology based on the sensor is few in steps, extremely high in qualified rate, good in long-term stability of products and convenient for large-scale batch production.

Description

technical field [0001] The invention belongs to the field of MEMS micromachining and manufacturing, and in particular relates to a MEMS absolute pressure sensor and a processing method thereof. Background technique [0002] Different from traditional mechanical pressure sensors, Micro-Electro-Mechanical System (MEMS) pressure sensors are widely used in the aerospace field due to their advantages of small size, light weight, low power consumption and integration. , Vacuum instrumentation equipment, industrial site control and detection, land-based and marine meteorology, health monitoring and smart medical care and other fields. How to achieve low-cost small-volume packaging and reliable electrical extraction technology is a key factor in determining the stability and commercialization of MEMS pressure sensors. [0003] Compared with MEMS pressure sensors with other principles, MEMS capacitive pressure sensors have many advantages such as simple structure, high yield, high o...

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Problems solved by technology

[0004] However, in the packaging method of the vacuum reference cavity of the MEMS capacitive pressure sensor, the silicon-silicon direct bonding needs to be annealed at a high temperature above 800°C, and the metal thermocompression bonding needs to use the expensive TSV process to complete the electrode preparation, BCB and glass paste. Although bonding is conducive to the airtightness of the electrodes passing through the bonding area, the working temperature of the sensor is limited and the vacuum degree of the vacuum reference chamber is not good; in the electrode extraction method, the metal electrode leads passing through the bonding layer are likely to cause air leakage, which is not conducive to the sensor long-term stability, while the TSV electrode preparation technology is relatively expensive, the degree of commercialization is not good, and the long-term stability needs to be verified

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