Capacitive humidity sensor of integrated ultrasonic structure and preparation method of capacitive humidity sensor of integrated ultrasonic structure

Abstract

The invention discloses a capacitive humidity sensor of an integrated ultrasonic structure and a preparation method of the capacitive humidity sensor of the integrated ultrasonic structure. The capacitive humidity sensor comprises an ultrasonic transducer structure and multiple humidity sensitive capacitor structures, wherein the humidity sensitive capacitor structures are arranged above the ultrasonic transducer structure; the ultrasonic transducer structure comprises a substrate, a piezoelectric material layer and an intermediate metal layer which are sequentially arranged from bottom to top; the humidity sensitive capacitor structures comprise insulating layers, interdigital electrodes, passivation layers and humidity sensitive material layers which are sequentially arranged from bottom to top; the insulating layers are arranged on the intermediate metal layer; a cavity is formed in the lower surface of the substrate by corrosion and is used for adjusting the thickness of the substrate and further adjusting the resonant frequency of the ultrasonic transducer structure. The ultrasonic transducer releases an ultrasonic signal under the action of an electric signal with a certain frequency, so that energy is obtained by water molecules, the movement rate is increased, and water molecules relatively fast diffuse or escape from humidity sensitive materials. Therefore, the response speed of the sensor is increased.

Description

technical field [0001] The invention relates to a capacitive humidity sensor with an integrated ultrasonic structure and a preparation method thereof, belonging to micro-electromechanical technology. Background technique [0002] The humidity sensor is a device for measuring humidity, which is widely used in meteorological research, industrial production and other fields. Due to the limited movement rate of water molecules, when the ambient humidity changes, it takes a period of response time for the measurement results of the sensor to change; and the existence of hysteresis in the sensor has a negative impact on the measurement accuracy of the sensor. [0003] In order to improve the response characteristics and hysteresis characteristics of the sensor, the method usually used at present is to add a heating structure in the sensor structure. Vaisala (company name) uses a bent resistor in its product to heat the humidity sensor. In 2006, Ching-Liang Dai (name) and others ...

AI Technical Summary

Problems solved by technology

However, the humidity sensor using the heating structure can only measure the humidity normally after going through the process of heating up and cooling down, and the measurement frequency is affected by the temperature change rate of the sensor, which needs to be improved

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