A piezoelectric mems acoustic sensor

Abstract

A piezoelectric MEMS acoustic sensor provided by the present invention includes a substrate, an internal electrode area and an external electrode area, and the external electrode area is located on the periphery of the internal electrode area, and the internal electrode area and the external electrode area both include a top-to-bottom stack The top electrode, the upper piezoelectric layer, the middle electrode, the lower piezoelectric layer and the bottom electrode; the top electrode, the middle electrode and the bottom electrode in the inner electrode area and the top electrode, the middle electrode and the bottom electrode in the outer electrode area are spaced from each other; A lower supporting layer is arranged on the top of the base, the inner electrode area and the outer electrode area are located on the lower supporting layer, and the upper supporting layer made of silicon-based material is arranged on the top surfaces of the inner electrode area and the outer electrode area. The invention has high sensitivity and enhanced ability to withstand hydrostatic pressure: the MEMS acoustic sensor can meet the application requirements of different pressure resistance and working water depth.

Description

technical field [0001] The invention belongs to the field of MEMS sensors, in particular to a piezoelectric MEMS acoustic sensor. Background technique [0002] With the development of microelectronics technology, integrated circuit technology and processing technology, MEMS sensors have greatly promoted the development of sensors due to their advantages such as small size, light weight, low power consumption, high reliability, high sensitivity, easy integration and resistance to harsh working environments. Miniaturization, intelligence, multi-function and network development. MEMS sensors are gradually occupying the sensor market and gradually replacing the dominant position of traditional mechanical sensors. They have been favored by various fields such as consumer electronics, automobile industry, aerospace, marine equipment, machinery, chemical industry and medicine. [0003] At present, the existing high-sensitivity piezoelectric MEMS acoustic sensor uses AlN material t...

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Problems solved by technology

[0003] At present, the existing high-sensitivity piezoelectric MEMS acoustic sensor uses AlN material to prepare its piezoelectric layer. Due to Mo / AlN / Mo / AlN / Mo, the thickness of the double-electrode bimorph structure is subject to the manufacturing process, and there is a thickness The maximum value of about 2um, can not work under higher pressure

In order to improve the pressure resistance of the sensor, a lower support layer is also added under the piezoelectric layer of the sensor. The piezoelectric layer is a single-layer structure (that is, similar to the lower support layer + Mo / AlN / Mo structure), and the corresponding sound pressure sensitivity is low. That is, it is not suitable for scenes that require higher sensitivity under higher pressure environments

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