CN-121984472-A - Ultra-small electromechanical coupling coefficient resonator, implementation method and ultra-narrow band filter

CN121984472ACN 121984472 ACN121984472 ACN 121984472ACN-121984472-A

Abstract

The invention provides an ultra-small electromechanical coupling coefficient resonator, an implementation method and an ultra-narrow band filter, wherein the method comprises the following steps: and applying preset pulse voltage to electrodes of the bulk acoustic wave resonator with the ferroelectric layer in the piezoelectric layer to realize the overturning of the local polarization direction of the preset area of the ferroelectric layer of the bulk acoustic wave resonator, thereby obtaining the bulk acoustic wave resonator with ultra-small integral electromechanical coupling coefficient. The invention applies a first pulse voltage to the resonator based on ferroelectric materials, locally turns over the polarization direction of the ferroelectric layer to obtain the bulk acoustic wave resonator with ultra-small electromechanical coupling coefficient, meets the application requirement of an ultra-narrow band filter with ultra-high frequency, can also be provided with a second piezoelectric layer between a first electrode and a second electrode to partially offset the piezoelectric coefficient of the ferroelectric layer, greatly reduces the electromechanical coupling coefficient of the resonator, realizes the ultra-narrow bandwidth filter, and finally realizes the filter with narrower bandwidth through the selection of the materials and the thickness of the electrodes.

Inventors

QIN RUIDONG
MU ZHIQIANG
HUANG XUANQI
YU WENJIE

Assignees

中国科学院上海微系统与信息技术研究所

Dates

Publication Date: 20260505
Application Date: 20251226

Claims (10)

1. A method for implementing an ultra-small electromechanical coupling coefficient resonator, the method comprising: and applying preset pulse voltage to electrodes of the bulk acoustic wave resonator with the ferroelectric layer in the piezoelectric layer to realize the overturning of the local polarization direction of the preset area of the ferroelectric layer of the bulk acoustic wave resonator, thereby obtaining the bulk acoustic wave resonator with ultra-small integral electromechanical coupling coefficient.
2. An ultra-small electromechanical coupling coefficient resonator, wherein the resonator achieves an ultra-small electromechanical coupling coefficient using the ultra-small electromechanical coupling coefficient resonator implementation method of claim 1, the resonator comprising: The first electrode is electrically connected with a preset first pulse voltage source; The second electrode is electrically connected with a preset second pulse voltage source or grounded; A first piezoelectric layer, the first piezoelectric layer being a ferroelectric layer, the first piezoelectric layer being located between the first electrode and the second electrode; and the acoustic mirror structure is positioned on one surface of the second electrode, which is far away from the first piezoelectric layer.
3. The ultra-small electromechanical coupling coefficient resonator according to claim 2, wherein the material of the first piezoelectric layer is an Al (1-x) Sc x N thin film, wherein x is 20% or more, and/or the thickness of the first piezoelectric layer is 0.01 μm to 1. Mu.m.
4. A microelectromechanical coupling coefficient resonator of claim 2 or 3, characterized in that the resonator further comprises a second piezoelectric layer, the second piezoelectric layer being located between the first piezoelectric layer and the second electrode.
5. The mems resonator of claim 4 wherein the second piezoelectric layer is a ferroelectric layer of opposite polarity to the first piezoelectric layer or wherein the second piezoelectric layer is a ferroelectric layer of the same polarity as the first piezoelectric layer.
6. The mems resonator of claim 4, wherein the second piezoelectric layer is a piezoelectric film that is not a ferroelectric layer, and wherein a piezoelectric stress constant thickness product of the second piezoelectric layer is 70% -130% of a piezoelectric stress constant thickness product of the first piezoelectric layer.
7. The mems resonator of claim 2, wherein the first electrode and the second electrode are each at least one of Au, ag, ru, W, mo, ir, al, pt, nb and Hf, and/or the first electrode and the second electrode are each 0.01-0.5 microns thick.
8. The mems resonator of claim 2, wherein the acoustic mirror structure is at least one of a bragg reflective layer, a cavity, or a photonic crystal mirror.
9. An ultra-narrow band filter constructed from a cascade of two or more ultra-small electromechanical coupling coefficient resonators as claimed in any one of claims 2 to 8.
10. The ultra-narrow band filter of claim 9, wherein the cascade topology used by the ultra-small electromechanical coupling coefficient resonator to construct the ultra-narrow band filter is any one of a ladder structure, a lattice structure, and a hybrid structure.

Description

Ultra-small electromechanical coupling coefficient resonator, implementation method and ultra-narrow band filter Technical Field The invention belongs to the technical field of electronic devices, and particularly relates to an ultra-small electromechanical coupling coefficient resonator, an implementation method and an ultra-narrow band filter. Background Ultra-narrow band communication can improve the anti-interference capability of network connection, enlarge the signal coverage range and support more devices to access the network simultaneously by using a very narrow working frequency band. This technology has become an important technical solution for communication systems such as internet of things (Internet of Things, ioT), low-Power Wide-Area Network (LPWA), wireless local Area Network (Wi-Fi), and the like. As communication frequencies expand to higher frequency bands, higher demands are placed on frequency selectivity and bandwidth control of radio frequency front-end devices. Bulk acoustic wave filters (Bulk Acoustic Wave, BAW) based on Aluminum Nitride (AlN) materials have the advantages of high operating frequency, low insertion loss, high frequency selectivity, high power capacity, strong antistatic capability and the like, and are widely applied to radio frequency front ends in the communication field. However, the prior art has been hampered by the fact that the further reduction of the bandwidth of ultra-narrow band filters is achieved, which is mainly limited by the high electromechanical coupling coefficient (Electromechanical Coupling Coefficient, K2) inherent to AlN materials, which makes it difficult to reduce the relative bandwidth (Fractional Bandwidth, FBW) of the filter below 1%. Although the bandwidth can be compressed to a certain extent by circuit optimization, impedance matching or structure fine tuning at present, physical limits of the material cannot be broken through, and the added circuit structure can complicate the radio frequency system more and cause adverse effects on other radio frequency performances of the filter. Therefore, there is a need for a bulk acoustic wave filter structure or method of operation that can achieve a narrower bandwidth while maintaining a high Q value and low loss. It should be noted that the foregoing description of the background art is only for the purpose of providing a clear and complete description of the technical solutions of the present application and is thus convenient for a person skilled in the art to understand, and it should not be construed that the above technical solutions are known to the person skilled in the art merely because these solutions are described in the background art section of the present application. Disclosure of Invention In view of the above drawbacks of the prior art, an object of the present invention is to provide an ultra-small electromechanical coupling coefficient resonator, an implementation method, and an ultra-narrow band filter for solving the problem that it is difficult to implement a narrower bandwidth while maintaining a high Q value and low loss in the bulk acoustic wave filter in the prior art. To achieve the above object, the present invention provides a method for implementing an ultra-small electromechanical coupling coefficient resonator, the method comprising: and applying preset pulse voltage to electrodes of the bulk acoustic wave resonator with the ferroelectric layer in the piezoelectric layer to realize the overturning of the local polarization direction of the preset area of the ferroelectric layer of the bulk acoustic wave resonator, thereby obtaining the bulk acoustic wave resonator with ultra-small integral electromechanical coupling coefficient. The invention also provides a resonator with the ultra-small electromechanical coupling coefficient, which realizes the ultra-small electromechanical coupling coefficient by adopting the method for realizing the ultra-small electromechanical coupling coefficient resonator, and comprises the following steps: The first electrode is electrically connected with a preset first pulse voltage source; The second electrode is electrically connected with a preset second pulse voltage source or grounded; A first piezoelectric layer, the first piezoelectric layer being a ferroelectric layer, the first piezoelectric layer being located between the first electrode and the second electrode; and the acoustic mirror structure is positioned on one surface of the second electrode, which is far away from the first piezoelectric layer. Optionally, the material of the first piezoelectric layer is an Al (1-x)Scx N film, wherein x is more than or equal to 20%, and/or the thickness of the first piezoelectric layer is 0.01-1 micrometer. Optionally, the resonator further comprises a second piezoelectric layer, the second piezoelectric layer being located between the first piezoelectric layer and the second electrode. Optionally, the second piezoelectric layer i