Absolute pressure transducer chip based on surface micro-machining and its production method

Abstract

The invention relates to an absolute pressure sensor chip based on surface micromachining and a manufacturing method. The manufacturing method is characterized by comprising the following steps: adopting a low-stress silicon nitride film as a core structural layer of the pressure sensor chip and using a polycrystalline silicon film to form a force-sensitive resistor track; designing a film area of the low-stress silicon nitride film into a long rectangle, fully utilizing longitudinal piezoresistive effect of the polycrystalline silicon resistor track according to the stress distribution of the film area, and making the most of a tensile stress area on the film to put part of a pair of resistor tracks on the external surface of the film and arrange another two resistor tracks on the central position of the film; and separately contacting a folded bent angle part of each resistor track with a hole depositing metal to conduct the bent angle part. By adopting surface micromachining technology compatible with IC technology, the method can manufacture the absolute pressure sensor chip with a measuring range of 1KPa-1MPa and with high sensitivity, good stability and high precision.

Description

technical field [0001] The present invention relates to providing an absolute pressure sensor chip based on surface micromachining and its manufacturing method, more precisely, providing a low-stress silicon nitride film as a structural layer, and a polysilicon film forming a force-sensitive resistor and adopting surface micromachining An absolute pressure sensor chip and a manufacturing method thereof belong to the technical field of silicon micromechanical sensors. Background technique [0002] The piezoresistive pressure sensor appeared in the 1960s. The subsequent development of micromachining technology made the sensitive components miniaturized, the sensor production was mass-produced, and the cost was reduced. It established a dominant position in the field of pressure measurement. Compared with the traditional Membrane potentiometer, force balance, variable inductance, variable capacitance, metal strain gauge and semiconductor strain gauge sensors are much more advan...

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Problems solved by technology

[0004] However, the fabrication of the absolute pressure sensor chip based on bulk micromachining has the following disadvantages: first: the pn junction is isolated between the resistance after power-on and the silicon substrate, and when the temperature of the device is above 100°C, the pn junction The leakage current is very large, which makes the device unable to work, so it cannot meet the use of stress test in medium and high temperature environment

Second: In order to obtain a vacuum reference cavity for absolute pressure testing, two silicon wafers must be pre-processed, bonded at high temperature in a vacuum environment, and must be polished and thinned again, so the initial cost is high and the process is complicated

Third: For pressure sensors processed by bulk micromachining, anisotropic wet deep etching must be performed on the back of the silicon wafer to meet the requirements of low-range testing after thinning. Area is much smaller than surface micromachining

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