CN-122026853-A - Acoustic wave resonator, preparation method thereof and filter

CN122026853ACN 122026853 ACN122026853 ACN 122026853ACN-122026853-A

Abstract

The invention discloses an acoustic wave resonator, a preparation method thereof and a filter, and relates to the technical field of filters. The acoustic wave resonator comprises a substrate, a bottom electrode, a piezoelectric layer, a temperature compensation layer, a top electrode and a top electrode, wherein the bottom electrode is positioned on one side of the substrate, the piezoelectric layer is positioned on one side of the bottom electrode, which is away from the substrate, the piezoelectric layer comprises a plurality of grooves which are arranged at intervals, the temperature compensation layer is at least partially filled in the grooves, the top electrode is positioned on one side of the piezoelectric layer, which is away from the bottom electrode, and the top electrode comprises a middle part and an edge part which surrounds the middle part, and the edge part is in a step shape. According to the technical scheme, the grooves are formed in the piezoelectric layer of the acoustic wave resonator in the middle, and the temperature compensation layer is at least partially filled in the grooves, so that the temperature stability and the filtering performance of the acoustic wave resonator are improved.

Inventors

SUN CHENGLIANG
GAO CHAO
WANG ZEKAI
CAI YAO
DAI JINHAO
GUO SHISHANG

Assignees

武汉敏声新技术有限公司

Dates

Publication Date: 20260512
Application Date: 20260128

Claims (12)

1. An acoustic wave resonator, comprising: A substrate; A bottom electrode located at one side of the substrate; the piezoelectric layer is positioned on one side of the bottom electrode, which is away from the substrate, and comprises a plurality of grooves which are arranged at intervals; the temperature compensation layer is at least partially filled in the groove; The piezoelectric device comprises a piezoelectric layer, a bottom electrode, a top electrode and a top electrode, wherein the piezoelectric layer is arranged on one side of the bottom electrode, the side of the piezoelectric layer is away from the bottom electrode, the top electrode comprises a middle part and an edge part surrounding the middle part, and the edge part is in a step shape.
2. The acoustic wave resonator according to claim 1, characterized in that the edge portion comprises a first step structure and a second step structure connected to each other; The first step structure is overlapped with the piezoelectric material of the piezoelectric layer, and the second step structure is overlapped with the temperature compensation material filled in the groove along the direction perpendicular to the plane of the substrate; or along the direction perpendicular to the plane of the substrate, the first step structure is overlapped with the temperature compensation material filled in the groove, and the second step structure is overlapped with the piezoelectric material of the piezoelectric layer.
3. The acoustic wave resonator according to claim 1, further comprising a protective layer; The protective layer covers the piezoelectric layer and the temperature compensation layer.
4. The acoustic wave resonator of claim 1, wherein the temperature compensating layer comprises a first temperature compensating structure and a second temperature compensating structure; The first temperature compensation structure is filled in the groove; The second temperature compensation structure is positioned on one side of the piezoelectric layer, which is away from the bottom electrode, and comprises a window structure, and the top electrode is positioned in the window structure.
5. The acoustic wave resonator according to claim 1, characterized in that a cavity structure is provided between the substrate and the bottom electrode, or the substrate comprises at least one layer of low acoustic impedance material and at least one layer of high acoustic impedance material alternately stacked.
6. The acoustic wave resonator of claim 1, further comprising an active region and a passive region surrounding the active region; The density of the plurality of grooves in the piezoelectric layer of the active region is lower than the density of the plurality of grooves in the piezoelectric layer of the passive region.
7. The acoustic wave resonator according to claim 6, characterized in that a plurality of the trench arrays of the piezoelectric layer of the active region are arranged.
8. The acoustic wave resonator of claim 6 wherein the piezoelectric layer of the inactive region comprises a plurality of concentric annular grooves or a plurality of the grooves of the piezoelectric layer of the inactive region form a phonon crystal array.
9. A method of making an acoustic wave resonator comprising: Providing a substrate; Forming a bottom electrode and a piezoelectric layer on one side of the substrate in sequence; patterning the piezoelectric layer to form a plurality of grooves in the piezoelectric layer, wherein the grooves are arranged at intervals; forming a temperature compensation layer at least filled in the groove; The piezoelectric layer comprises a piezoelectric layer, a bottom electrode, a top electrode and a top electrode, wherein the top electrode is positioned on one side of the piezoelectric layer, which is away from the bottom electrode, and comprises a middle part and an edge part surrounding the middle part, and the edge part is in a step shape.
10. The method of manufacturing an acoustic wave resonator according to claim 9, wherein forming a temperature compensation layer at least filling in the trench comprises: Depositing a temperature compensation material on one side of the piezoelectric layer away from the bottom electrode to form a first temperature compensation structure filled in the groove and a second temperature compensation structure positioned on one side of the piezoelectric layer away from the bottom electrode; Patterning the second temperature compensation structure to form a window structure in the second temperature compensation structure, wherein the top electrode is positioned in the window structure.
11. The method of manufacturing an acoustic wave resonator according to claim 9, further comprising, before sequentially forming a bottom electrode and a piezoelectric layer on one side of the substrate: forming a first sacrificial layer on one side of the substrate; Forming a top electrode comprising: Forming a second sacrificial layer covering the temperature compensation layer, wherein the materials of the first sacrificial layer and the second sacrificial layer are the same; Patterning the second sacrificial layer to form an electrode trench in the second sacrificial layer, wherein the electrode trench comprises a plurality of coaxial and communicated sub-electrode trenches, and the size of the sub-electrode trench close to the substrate is smaller than that of the sub-electrode trench far away from the substrate; Forming the top electrode in the electrode trench; removing the first sacrificial layer and the second sacrificial layer to make an edge portion of the top electrode step-shaped and form a cavity between the substrate and the bottom electrode; Wherein the edge portion includes a first step structure and a second step structure connected to each other; The first step structure is overlapped with the piezoelectric material of the piezoelectric layer, and the second step structure is overlapped with the temperature compensation material filled in the groove along the direction perpendicular to the plane of the substrate; or along the direction perpendicular to the plane of the substrate, the first step structure is overlapped with the temperature compensation material filled in the groove, and the second step structure is overlapped with the piezoelectric material of the piezoelectric layer.
12. A filter comprising an acoustic wave resonator according to any one of claims 1 to 8.

Description

Acoustic wave resonator, preparation method thereof and filter Technical Field The embodiment of the invention relates to the technical field of filters, in particular to an acoustic wave resonator, a preparation method thereof and a filter. Background The rapid development of wireless communication technology, especially the wide application of high-frequency communication systems such as 5G, internet of things, etc., puts forward higher demands on the performance of radio frequency front-end devices. The film bulk acoustic resonator (Film Bulk Acoustic Resonator, FBAR) has become a key rf filter device due to its small size, high quality factor, low loss, and good compatibility with integrated circuit processes, and is widely used for selection of high frequency signals. The frequency of the acoustic wave resonator is easy to deviate under the temperature change, which can cause signal crosstalk in a modern communication system with extremely small adjacent channel spacing and seriously affect the communication stability. In the prior art, in order to improve the temperature stability of the acoustic wave resonator, a whole layer of temperature compensation material with a negative temperature coefficient is generally stacked above or on the upper side and the lower side of the piezoelectric layer, so as to offset the resonance frequency drift caused by the temperature rise of the piezoelectric material. However, when the acoustic wave resonator works, the vertical laminated structure is easy to cause performance degradation problems such as reduced electroacoustic coupling coefficient, reduced quality factor, narrow filter bandwidth and the like of the acoustic wave resonator, and it is difficult to combine the temperature compensation effect and the performance of the device. Disclosure of Invention The invention provides an acoustic wave resonator, a preparation method thereof and a filter, and the temperature stability and the filtering performance of the acoustic wave resonator are improved by embedding a temperature compensation layer in a piezoelectric layer. A first aspect of the present invention provides an acoustic wave resonator comprising: A substrate; A bottom electrode located at one side of the substrate; the piezoelectric layer is positioned on one side of the bottom electrode, which is away from the substrate, and comprises a plurality of grooves which are arranged at intervals; the temperature compensation layer is at least partially filled in the groove; The piezoelectric device comprises a piezoelectric layer, a bottom electrode, a top electrode and a top electrode, wherein the piezoelectric layer is arranged on one side of the bottom electrode, the side of the piezoelectric layer is away from the bottom electrode, the top electrode comprises a middle part and an edge part surrounding the middle part, and the edge part is in a step shape. Optionally, the edge portion includes a first step structure and a second step structure connected to each other; The first step structure is overlapped with the piezoelectric material of the piezoelectric layer, and the second step structure is overlapped with the temperature compensation material filled in the groove along the direction perpendicular to the plane of the substrate; or along the direction perpendicular to the plane of the substrate, the first step structure is overlapped with the temperature compensation material filled in the groove, and the second step structure is overlapped with the piezoelectric material of the piezoelectric layer. Optionally, the acoustic wave resonator further comprises a protective layer; The protective layer covers the piezoelectric layer and the temperature compensation layer. Optionally, the temperature compensation layer comprises a first temperature compensation structure and a second temperature compensation structure; The first temperature compensation structure is filled in the groove; The second temperature compensation structure is positioned on one side of the piezoelectric layer, which is away from the bottom electrode, and comprises a window structure, and the top electrode is positioned in the window structure. Optionally, a cavity structure is disposed between the substrate and the bottom electrode, or the substrate includes at least one low acoustic impedance material layer and at least one high acoustic impedance material layer alternately stacked. Optionally, the acoustic wave resonator further comprises an active region and an inactive region surrounding the active region; The density of the plurality of grooves in the piezoelectric layer of the active region is lower than the density of the plurality of grooves in the piezoelectric layer of the passive region. Optionally, a plurality of the trenches of the piezoelectric layer of the active region are arranged in an array. Optionally, the piezoelectric layer of the inactive region includes a plurality of concentric annular grooves, or the p