CN-122003091-A - High-sensitivity PMUT and preparation method thereof

CN122003091ACN 122003091 ACN122003091 ACN 122003091ACN-122003091-A

Abstract

The invention belongs to the field of sensors, and particularly relates to a high-sensitivity PMUT and a preparation method thereof, wherein the preparation method comprises the steps of preparing a vibrating diaphragm structure of a piezoelectric micromechanical ultrasonic transducer, wherein the vibrating diaphragm structure comprises a silicon substrate, an oxygen burying layer, a passive layer, a lower electrode layer, a piezoelectric layer and an upper electrode layer from bottom to top; in a non-anchoring area and/or a central vibration area of a vibrating diaphragm structure of the piezoelectric micro-mechanical ultrasonic transducer, weakening rigidity of a piezoelectric layer and/or an upper electrode layer to obtain the high-sensitivity piezoelectric micro-mechanical ultrasonic transducer; the invention not only improves the electromechanical coupling coefficient, but also improves the acoustic output capability of the transducer when being used as a transmitter and the sensitivity when being used as a receiver.

Inventors

ZHANG WEN
WANG FEI
LIU WENYI
WANG LU
LIAO SONGLIN
WANG DENGPAN
HUANG JING
YANG JING

Assignees

中国电子科技集团公司第二十六研究所

Dates

Publication Date: 20260508
Application Date: 20260205

Claims (6)

1. The preparation method of the high-sensitivity PMUT is characterized by comprising the following steps of: s1, preparing a vibrating diaphragm structure of a piezoelectric micromechanical ultrasonic transducer, wherein the vibrating diaphragm structure comprises a silicon substrate, an oxygen burying layer, a passive layer, a lower electrode layer, a piezoelectric layer and an upper electrode layer from bottom to top; S2, weakening rigidity of the piezoelectric layer and/or the upper electrode layer in a non-anchoring area and/or a central vibration area of a vibrating diaphragm structure of the piezoelectric micro-mechanical ultrasonic transducer to obtain the high-sensitivity piezoelectric micro-mechanical ultrasonic transducer.
2. The method of manufacturing a PMUT with high sensitivity according to claim 1, wherein the step S2 of weakening the rigidity of the piezoelectric layer and/or the upper electrode layer comprises: And etching the piezoelectric layer and/or the non-anchoring area and/or the central vibration area corresponding to the upper electrode layer according to a designed etching pattern by utilizing an MEMS etching process.
3. The method of manufacturing a PMUT with high sensitivity according to claim 2, wherein the etching pattern is designed according to performance requirements and structural characteristics.
4. The method of claim 1, wherein the passive layer is made of silicon, silicon dioxide or a composite material.
5. The method for preparing a high-sensitivity PMUT according to claim 1, wherein the piezoelectric layer is made of lead zirconate titanate, aluminum nitride, or scandium aluminum nitride.
6. A high sensitivity PMUT prepared by a method according to any one of claims 1 to 5.

Description

High-sensitivity PMUT and preparation method thereof Technical Field The invention belongs to the field of sensors, and particularly relates to a high-sensitivity PMUT and a preparation method thereof. Background The piezoelectric micromachined ultrasonic transducer (Piezoelectric Micromachined Ultrasonic Transducer, PMUT) is a miniature ultrasonic transducer based on the piezoelectric effect, and is manufactured by using the Micro Electro Mechanical System (MEMS) technology, and can realize the functions of transmitting and receiving ultrasonic waves. PMUT, as a new generation of ultrasonic transducer, opens up a wide application prospect in the medical, industrial and consumer electronics fields by virtue of advantages of miniaturization, low power consumption, high integration and the like. In the medical field, medical ultrasound imaging requires a transducer with a high penetration depth. However, the conventional solid-supported Piezoelectric Micromachined Ultrasonic Transducer (PMUT) is limited by its low electromechanical coupling coefficient, resulting in insufficient conversion efficiency from electrical energy to mechanical energy, low acoustic output energy, and difficulty in meeting the requirements of deep tissue imaging. PMUTs typically employ a multilayer thin film structure including a passive layer, a lower electrode, a piezoelectric layer, and an upper electrode. The structure has high rigidity, limits vibration displacement and further leads to lower electromechanical coupling coefficient. In the existing optimization method, although the material modification can improve the performance to a certain extent, the improvement effect is limited and the process is complex, and if the electromechanical coupling coefficient is enhanced by improving the driving voltage, the aging of the device is accelerated. Disclosure of Invention The invention provides a high-sensitivity PMUT and a preparation method thereof, and aims to solve the problem that the electromechanical coupling coefficient of a solid-supported piezoelectric micro-mechanical ultrasonic transducer is insufficient so as to influence the penetration depth of the solid-supported piezoelectric micro-mechanical ultrasonic transducer in medical ultrasonic imaging. In a first aspect, the present invention provides a method for preparing a high sensitivity PMUT, comprising the steps of: s1, preparing a vibrating diaphragm structure of a piezoelectric micromechanical ultrasonic transducer, wherein the vibrating diaphragm structure comprises a silicon substrate, an oxygen burying layer, a passive layer, a lower electrode layer, a piezoelectric layer and an upper electrode layer from bottom to top; S2, weakening rigidity of the piezoelectric layer and/or the upper electrode layer in a non-anchoring area and/or a central vibration area of a vibrating diaphragm structure of the piezoelectric micro-mechanical ultrasonic transducer to obtain the high-sensitivity piezoelectric micro-mechanical ultrasonic transducer. Further, the step S2 of weakening the rigidity of the piezoelectric layer and/or the upper electrode includes: and etching on the non-anchor area and/or the central vibration area corresponding to the piezoelectric layer and/or the upper electrode layer according to the designed etching pattern by utilizing the MEMS etching process, and removing the etching pattern. Further, the passive layer is made of silicon, silicon dioxide or composite materials. Further, the piezoelectric layer is made of lead zirconate titanate, aluminum nitride or scandium aluminum nitride. In a second aspect, the present invention provides a high sensitivity PMUT, prepared using a high sensitivity PMUT as described in the first aspect and a method of preparing the same. The invention has the beneficial effects that: The rigidity of the multilayer structure of the solid-supported piezoelectric micromachined ultrasonic transducer is reduced by introducing the carefully designed local rigidity weakening area, so that the multilayer structure can generate larger vibration displacement under the same driving voltage or generate higher electric signal output under the same sound pressure effect. Not only the electromechanical coupling coefficient is improved, but also the acoustic output capability of the transducer when being used as a transmitter and the sensitivity of the transducer when being used as a receiver are improved, so that the penetration depth and the signal-to-noise ratio of the transducer in medical ultrasonic imaging, industrial nondestructive testing and other applications are effectively improved. Drawings FIG. 1 is a schematic diagram of a conventional solid support PMUT structure; FIG. 2 is a schematic diagram of the structure of a high sensitivity PMUT according to the present invention; FIG. 3 is a top view of an electrode structure of a high sensitivity PMUT according to the present invention; FIG. 4 is a schematic diagram showing the compa