Resonant micro-pressure sensor and preparation method thereof

Abstract

The invention discloses a resonant micro-pressure sensor and a preparation method thereof. The resonant micro-pressure sensor sequentially comprises a substrate layer, a buried oxide layer, a device layer and a packaging cover plate from bottom to top, wherein the substrate layer comprises a pressure sensitive film and a first boss arranged on the pressure sensitive film, and the first boss is used for constructing a stress concentration area, improving the pressure sensitivity of the resonant micro-pressure sensor and improving the rigidity of the pressure sensitive film. The device layer comprises a first resonance unit, a second resonance unit and a silicon island region comprising a plurality of silicon island units. According to the resonant micro-pressure sensor, the stress concentration area is constructed through the design of the bosses on the pressure sensitive film; the first resonance unit and the second resonance unit are respectively arranged in areas with maximum positive stress and negative stress, so that the pressure sensitivity of the micro-pressure sensor is improved; in addition, the first boss on the pressure sensitive film also adjusts the characteristic frequency of the pressure sensitive film, so that the resonance unit avoids the modal interference of the pressure sensitive film in the working range.

Description

technical field [0001] The invention relates to the technical field of MEMS micro-sensors, in particular to a resonant micro-pressure sensor and a preparation method thereof. Background technique [0002] The micro-pressure sensor is mainly for the measurement of small pressure. The pressure measurement range is generally within 10Pa to 10kPa. It is widely used in industrial control, biomedicine, semiconductor processing and manufacturing, aerospace, meteorological monitoring, interstellar exploration and other fields. [0003] Micro-pressure sensors can be roughly divided into three types according to the detection methods: piezoresistive, capacitive, and resonant. Among them, piezoresistive and capacitive micro-pressure sensors have relatively mature commercial products, but their measurement accuracy is mostly concentrated in 0.1% FS Above, it is difficult to meet the high-precision measurement requirements of up to 0.05% FS in aerospace, interstellar exploration and othe...

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Problems solved by technology

However, although the overload protection structure can be designed and manufactured on the package cover to suppress the excessive deformation of the pressure sensitive film, the bonding voltage is usually high during the anodic bonding process, and the pressure sensitive film is thin, which is prone to electrostatic attraction and makes the sensor The package cover plate and the sensitive core are bonded together, causing the sensor to fail

In addition, the resonant micro-pressure sensor will introduce a large residual thermal stress due to the difference in the bonding material during the anodic bonding process, resulting in a very large temperature sensitivity of the resonator, especially at low temperature, which will affect the overall accuracy of the sensor. greater impact,

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