Piezoelectric MEMS acoustic sensor

Abstract

The invention provides a piezoelectric MEMS acoustic sensor, which comprises a substrate, an internal electrode area and an external electrode area. The external electrode area is arranged at the periphery of the internal electrode area. Each of the internal electrode area and the external electrode area includes a top electrode, an upper piezoelectric layer, an intermediate electrode, a lower piezoelectric layer and a bottom electrode which are stacked from top to bottom. The top electrode, the intermediate electrode and the bottom electrode in the internal electrode area are spaced apart from the top electrode, the intermediate electrode and the bottom electrode in the external electrode area. A lower supporting layer is arranged at the top of the substrate; the internal electrode area and the external electrode area are both arranged on the lower supporting layer; and upper supporting layers made of silicon-based materials are arranged on the top face of the internal electrode areaand the top face of the external electrode area. The piezoelectric MEMS acoustic sensor has advantages of high sensitivity and enhanced hydrostatic pressure resistance; and the MEMS acoustic sensor can meet the application requirements of different pressure resistance and working water depths.

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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