A compact high-sensitivity MEMS micro-capacitive sensor

Abstract

The invention relates to a compact high-sensitivity MEMS micro-capacitance type sensor. The device comprises a substrate (10), a lower isolation layer (11), a lower electrode layer (12), an upper isolation layer (13), Sacrificial layer (14), and a diaphragm layer (15), an upper electrode layer (16), an insulating layer (17) which are sequentially arranged from bottom to top, The lower electrode layer (12) and the upper electrode layer (16) comprise at least one electrode array unit (22), the electrode array unit (22) comprises a plurality of electrode units, and the edges of the electrode units (19a) of the lower electrode layer (12) and/or the electrode units (19b) of the upper electrode layer (16) are provided with a plurality of notches (20). The overlapping area of the fixed parts of the electrodes of the capacitor structure is reduced, so that when the vibrating diaphragm vibrates, the larger the capacitance change amplitude is, the more obvious the impedance conversion can be caused after the characteristic frequency offset.

Description

technical field [0001] The invention belongs to the technical field of silicon micromachining, and in particular relates to a compact high-sensitivity MEMS microcapacitance sensor. Background technique [0002] With the development of the Internet of Things, the demand for MEMS sensors is also increasing. At present, many sensors use capacitive structures to detect environmental factors, such as gas sensors, ranging sensors, ultrasonic imaging sensors, and capacitive microphones. [0003] Among them, the MEMS capacitive gas sensor based on the characteristic frequency change is mainly to deposit and spin-coat the gas adsorption material on the vibration part of the upper surface of the sensor, and its mass will change slightly during adsorption and desorption. Moreover, when the operating frequency is high, such as in the ultrasonic frequency band, a small mass change can cause a change in the characteristic frequency, so that the vibration frequency of the vibrating part de...

AI Technical Summary

Problems solved by technology

[0004] The electrode part of the traditional MEMS capacitive gas sensor is generally circular, and the fixed part of the upper and lower electrodes has a large area, resulting in a relatively small effective area during vibration. Therefore, the sensitivity of the sensor is not very good

In addition, the size of the MEMS sensor is small, and the upper limit of the mass range of the gas that can be detected is low. There are certain deficiencies in the detection of some gases that exist in large quantities and require high precision.

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