Gas-liquid dual-purpose thermal flow sensor and preparation method thereof

Abstract

The invention provides a gas-liquid dual-purpose thermal flow sensor and a preparation method thereof. The sensor comprises a single crystal substrate, a heat insulation dielectric film, a supporting column, a heating resistor, a thermistor and an environment temperature measuring resistor; a heat insulation cavity is formed in the single crystal substrate, and the heat insulation dielectric film covers the heat insulation cavity and comprises a silicon nitride layer; the supporting column is located in the heat insulation cavity, one end of the supporting column is connected with the single crystal substrate, and the other end of the supporting column extends upwards to be connected with the heat insulation dielectric film. The heating resistor and the thermistor are located on the upper surface of the heat insulation dielectric film, and the environment temperature measuring resistor is located on the single crystal substrate outside the heat insulation dielectric film. Through the improved structure and process design, a silicon nitride layer with low stress and high strength is used as the heat insulation dielectric film, a plurality of supporting columns are formed in the heat insulation cavity, one end of each supporting column is fixed in the substrate on the lower surface of the heat insulation cavity, the other end of each supporting column is connected with the lower surface of the heat insulation dielectric film, so that the mechanical strength of the heat insulation dielectric film is improved, and liquid flow impact can be resisted.

Description

technical field [0001] The invention belongs to the technical field of silicon micromechanical sensors, and in particular relates to a gas-liquid dual-purpose thermal flow sensor and a preparation method thereof. Background technique [0002] With the rapid development of MEMS sensor structure design technology and silicon-based micromachining technology, MEMS thermal flow sensors prepared based on silicon-based micromachining technology are widely used in aviation due to their small chip size, low manufacturing cost, and high performance. Aerospace, industrial process monitoring, biochemical medicine and other fields. Especially in recent years, with the miniaturization of analytical instruments or equipment in the fine chemical industry and biomedicine, it is difficult for traditional flow measurement devices to meet the requirements in terms of manufacturing cost, volume size and performance. The miniaturization of flow sensors, Multi-fluid detection capability, high per...

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Problems solved by technology

[0006] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a gas-liquid dual-purpose thermal flow sensor and its preparation method to solve the problem that the existing thermal gas flow sensor cannot be used to detect liquid flow, and the existing The gas-liquid dual-purpose flow sensor has problems such as complex preparation process and large heat loss.

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