An electret capacitive ultrasonic sensor and its manufacturing method

Abstract

The invention discloses an electret capacitive ultrasonic sensor comprising a lower resistivity substrate, an electret material layer, an insulation layer, a support layer, a vibrating thin film and upper electrodes. A cavity two-dimensional array in the shape of a circle or in other shapes forms in the support layer, and is distributed in row or column alignment. Metal is deposited on the vibrating thin film as upper electrodes which are a graph array which is one-to-one corresponding to graphs of a substrate cavity array and connected to the substrate cavity array. According to the invention, through utilization of electret materials, a direct current electric field needed in working of a CMUT is provided, so that a novel capacitive ultrasonic sensor structure which does not need externally applied direct current bias voltages is realized. The electret capacitive ultrasonic sensor is advantaged by being low in power consumption, high in reliability, high in safety, being miniature, etc.

Description

technical field [0001] The invention relates to the field of capacitive ultrasonic sensors, in particular to an electret capacitive ultrasonic sensor and a manufacturing method thereof. Background technique [0002] Ultrasonic sensors are widely used in medical imaging, non-destructive testing, and ultrasonic microscopy. In recent years, a capacitive ultrasonic sensor has gradually become one of the main research directions of ultrasonic transducers. The capacitive ultrasonic sensor adopts the manufacturing method of large-scale integrated circuits, which is easy to integrate with electronic circuits, is suitable for manufacturing two-dimensional area array structures, can be manufactured in batches, and has low manufacturing costs. Compared with piezoelectric ultrasonic transducers, it has lower mechanical impedance and is not sensitive to temperature, so it has a wider range of applications. Miniaturization, integration, high resolution, low power consumption, and high s...

AI Technical Summary

Problems solved by technology

However, the traditional capacitive micromachined ultrasonic sensor (CMUT device) needs to provide a DC bias voltage of tens of volts, which greatly increases the complexity and difficulty of the peripheral integrated circuit. At the same time, the safe voltage that the human body can withstand is lower than 36V Therefore, traditional CMUT devices have problems such as high DC voltage, high risk, high power consumption, and difficult chip integration of the driving circuit, which is not conducive to the wide application of sensors.

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