MEMS flow sensor and preparation method thereof

Abstract

The invention relates to an MEMS flow sensor and a preparation method thereof. A silicon substrate of the sensor is internally provided with a closed cavity, a silicon oxide insulating layer is laid on the silicon substrate, and a thermopile, a first heating resistor and a second heating resistor are arranged on the silicon oxide insulating layer; the first heating resistor and the second heating resistor are located on the two sides of the thermopile respectively and are symmetrically arranged with the center line of the thermopile as the symmetry axis, first pressure welding blocks are arranged at the two ends of the first heating resistor respectively, second pressure welding blocks are arranged at the two ends of the second heating resistor respectively, and third pressure welding blocks are arranged at the two ends of the thermopile respectively; the thermopile, the first heating resistor and the second heating resistor are covered with a silicon oxide insulating layer, and the silicon oxide insulating layer is covered with a silicon nitride protective layer; a heat insulation groove is formed in the periphery of an integral structure formed by the thermopile, the first heating resistor and the second heating resistor; a silicon oxide protection layer and a silicon nitride protection layer are sequentially laid on the groove bottom of the heat insulation groove. According to the invention, the measurement precision is improved.

Description

technical field [0001] The invention relates to the technical field of flow sensor preparation, in particular to a MEMS flow sensor and a preparation method. Background technique [0002] MEMS is an industrial technology that combines mechanical engineering and microelectronics technology, and its operating range is generally at the micro-nano level. MEMS technology is usually based on semiconductor materials, using processes such as surface micromachining, deep etching, and bulk micromachining, as well as related processes in the field of integrated circuits to prepare devices. [0003] Flow measurement is of great significance in industrial production and process control, such as consumer electronics, automotive and medical fields. There are many types of flow sensors commonly used at present, and with the help of MEMS technology, they have a wider development and application space. Common types of flow sensors on the market include: (1) Early flow sensors based on simpl...

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Problems solved by technology

However, these flow sensors have their own advantages in different applications, and their shortcomings are also obvious

For example, volumetric, eddy current, and electromagnetic flow sensors usually exhibit large power consumption and volume; differential pressure flow sensors are more complicated to install, and heat loss flow sensors are greatly affected by external ambient temperature and have low accuracy; Type flow sensor has been widely studied because of its simple structure, no mechanical structure and easy integration, but in order to suppress the influence of temperature drift, it is usually necessary to add an additional temperature sensor near the flow sensor to measure the temperature of the base

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