Capacitance humidity sensor with temperature drift compensation and making method thereof

Abstract

The invention discloses a capacitance humidity sensor with temperature drift compensation and a making method thereof. The sensor main body adopts the surface micro-mechanical machining technology to form an isolation layer on a semiconductor substrate and a humidity sensing cantilever and upper and lower electrodes on the isolation layer, wherein a first humidity sensitive material layer, a humidity isolation layer and a second humidity sensitive material layer are piled up on the humidity sensing cantilever from bottom to top; and the upper electrode is covered on the lower surface of the first humidity sensitive material layer and forms sensitive capacitance with the lower electrode. When the ambient humidity changes, the size changes of the first humidity sensitive material layer and the second humidity sensitive material layer are different, so as to enable the humidity sensing cantilever to be deformed and then the upper electrode to be deformed, as a result, the capacitance between the upper and the lower electrodes is changed, and the change of the capacitance value can represent the change of the ambient temperature. When the ambient temperature changes, if the size changes of the two humidity sensitive material layers of the humidity sensing cantilever are the same, the effect of phase drift compensation is achieved, and the capacitance humidity sensor with the temperature drift compensation has the outstanding property of low temperature drift.

Description

technical field [0001] The invention relates to the technical field of humidity sensors realized by surface micromachining, in particular to a capacitive humidity sensor with temperature drift compensation and a manufacturing method thereof. Background technique [0002] Humidity sensors are widely used. Traditional humidity sensors are mainly humidity sensitive resistors. Although these sensors are low in cost, their accuracy is poor. Capacitive humidity sensor is another common structure of humidity sensor. This type of sensor has high sensitivity and is the main form of humidity sensor at present. Capacitive humidity sensing structures usually use polymer materials as the humidity-sensing medium. Due to the large thermal expansion coefficient of the humidity-sensing material, the humidity-sensing characteristics also change, so temperature compensation is required. For example, the humidity sensor of Sensirion in Switzerland adopts two consistent interdigitated structure...

AI Technical Summary

Problems solved by technology

However, the disadvantages of this structure are: first, it takes up a large chip area, and second, it requires complex circuits to realize capacitance differential compensation.

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