Thermopile gas mass flow sensor and preparation method thereof

Abstract

The present invention provides a thermopile gas mass flow sensor and a preparation method thereof, comprising: (111) a single crystal silicon substrate; a heat insulating film connected to the substrate, and together enclosing a heat insulating cavity; a heating element ; A pair of "<>"-shaped thermopiles are located on the lower surface of the thermal insulation film and symmetrically distributed on both sides of the heating element. The angle between the two contour lines at the tip of each thermopile is 120°. The thermopile consists of at least one For P along the <110> crystallographic direction suspended from the lower surface of the thermal insulation film + Monocrystalline silicon thermocouple arm and N + P composed of single crystal silicon thermocouple arms + Monocrystalline Silicon‑N + It is composed of single crystal silicon thermocouple pairs, and the two thermocouple arms, the thermopile and the heating element are isolated by isolation grooves. The structure of the present invention selects the single crystal silicon with the largest Seebeck coefficient, and can make the equivalent length of the thermocouple arm longer under the limited size, so as to improve the sensitivity of the sensor; in addition, the P value can be increased. + Monocrystalline Silicon‑N + Single crystal silicon thermocouple adjusts the range and measurement accuracy for the distance between the hot end and the single crystal silicon heating element.

Description

technical field [0001] The invention belongs to the technical field of silicon micromechanical sensors, in particular to a heat-pile gas mass flow sensor and a preparation method thereof. Background technique [0002] In recent years, as human beings have fully entered the era of intelligent information, the demand for information measurement and control is getting higher and higher. Among them, the measurement and control of gas flow is of great significance in the fields of biomedicine, aerospace, and industrial automation. With the continuous advancement of MEMS technology, gas mass flow sensors based on MEMS technology have become an important direction for the future development of gas flow sensors due to their advantages of high sensitivity, small size, low power consumption, and fast response time. In addition, in fluid measurement, due to the different types and properties of the fluid to be measured, different flow sensors are required for measurement, which brings...

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Problems solved by technology

[0005] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a thermal-pile gas mass flow sensor and its preparation method, which is used to solve the problem of the limited chip size of the thermal-pile gas mass flow sensor in the prior art. Sensitivity cannot be further improved, and the existing p + Problems such as high manufacturing cost due to complex heat sink structure and process in Si / metal thermal pile gas mass flow sensor

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