Micro electronmechanical system pressure sensor chip of beam film mechanism and preparation method thereof

Abstract

The invention discloses a microelectromechanical system pressure sensor chip of a beam-membrane mechanism and a preparation method thereof. It includes a glass substrate, an n-type monocrystalline silicon element body, an isolation layer, and a protective layer; the outer edge of the n-type monocrystalline silicon element body is supported above the glass substrate, and the middle part of the n-type monocrystalline silicon element body is a hollow structure. A closed cavity is formed between the two; the top wall of the closed cavity is provided with a diaphragm pressure-sensitive structure; the diaphragm pressure-sensitive structure is divided into a flat die layer and a beam-membrane mechanism layer; Composed of beams, the beam-membrane mechanism has the advantages of good linearity and high sensitivity. The varistor is made of single crystal silicon, and an isolation layer is provided between the pressure-sensitive film and the varistor, which further improves the sensitivity and temperature characteristics, and overcomes the defects in the prior art such as sensor failure caused by excessive temperature. The preparation process of the sensor is simple and easy, the cost is low, and the sensor is easy to be integrated and miniaturized.

Description

technical field [0001] The invention relates to a pressure sensor, in particular to a microelectromechanical system pressure sensor chip of a beam-membrane mechanism and a preparation method thereof. Background technique [0002] Micro-Electro-Mechanical System (MEMS) pressure sensors are mainly divided into capacitive and resistive. The capacitive type has high cost due to its complicated process. At present, MEMS pressure sensors are mainly used in silicon piezoresistive type. The piezoresistive type sensor has the characteristics of small size, high reliability, low cost and suitable for mass production. [0003] The resistive chip of the MEMS pressure sensor is based on the piezoresistive effect of the semiconductor material silicon. The semiconductor silicon is diffused on the substrate to form a Wheatstone bridge. When the varistor is subjected to mechanical stress, the pressure is converted into a voltage output through the Wheatstone bridge. The pressure-sensitive ...

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Problems solved by technology

[0005] For flat die mechanisms, sensitivity can be improved if the diaphragm thickness is reduced; however, the deflection increases substantially relative to the diaphragm thickness

[0006] The deflection of the sensor can be greatly reduced by using the island membrane mechanism, and the sensitivity output can be compensated by increasing the diaphragm size, but the sensor size also increases accordingly

[0007] In view of the deficiencies of the above two diaphragm mechanisms, many types of beam-membrane mechanisms have been proposed, but they still have many problems: the sensor is small in size and the pressure-sensitive film is thin, the linearity is slightly poor, the temperature characteristic is good but the sensitivity is lower than the bottom, The stress of the diaphragm is large but the deflection increases

Bulk silicon micromachining technology is characterized by mature technology, but it is not easy to integrate and miniaturize

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