CN-114629461-B - Surface acoustic wave resonator

CN114629461BCN 114629461 BCN114629461 BCN 114629461BCN-114629461-B

Abstract

The embodiment of the invention discloses a surface acoustic wave resonator which comprises a piezoelectric layer, an electrode layer positioned on the piezoelectric layer, wherein the electrode layer comprises a transducer, the transducer comprises a first bus bar, a first long finger, a first false finger, a second bus bar, a second long finger and a second false finger, the first bus bar and the second bus bar extend along a first direction and are oppositely arranged, the first long finger, the second false finger, the second long finger and the first false finger extend along a second direction and are positioned between the first bus bar and the second bus bar, the first long finger and the second false finger are oppositely arranged, the piezoelectric layer comprises at least one heterostructure, the depth of the heterostructure is larger than the thickness of the transducer, the propagation speed of a surface acoustic wave in the heterostructure is different from the propagation speed in the piezoelectric layer, the heterostructure extends along the first direction, and the heterostructure overlaps with the vertical projection of the transducer in the piezoelectric layer and does not overlap with the vertical projection of a first gap and a second gap in the piezoelectric layer. The invention suppresses the transmission of the transverse mode and improves the performance of the filter.

Inventors

MA YANGYANG
LIU XIAOJUN
Yao Ruoyan
SONG JIAJIA
ZHU DEJIN

Assignees

天通瑞宏科技有限公司

Dates

Publication Date: 20260505
Application Date: 20220323

Claims (7)

1. A surface acoustic wave resonator, comprising: A piezoelectric layer; An electrode layer on the piezoelectric layer; The electrode layer comprises a transducer, wherein the transducer comprises a first bus bar, a first long finger, a first false finger, a second bus bar, a second long finger and a second false finger, wherein the first bus bar and the second bus bar extend along a first direction and are oppositely arranged, the first long finger, the second false finger, the second long finger and the first false finger extend along a second direction and are respectively positioned between the first bus bar and the second bus bar, the first long finger and the first false finger are alternately arranged along the first direction and are respectively connected with the first bus bar, the second long finger and the second false finger are alternately arranged along the first direction and are respectively connected with the second bus bar, the first long finger and the second false finger are oppositely arranged, a first gap is reserved between the first long finger and the second false finger, the second long finger and the first false finger are oppositely arranged, and the second long finger and the first false finger are alternately arranged along the first direction, and the second finger are mutually crossed along the second direction, and the second gap is reserved between the first long finger and the second finger; The piezoelectric layer comprises at least one heterostructure, the depth of the heterostructure is larger than the thickness of the transducer, the propagation speed of the surface acoustic wave in the heterostructure is different from the propagation speed in the piezoelectric layer, the heterostructure extends along the first direction, the heterostructure is overlapped with the vertical projection of the transducer in the piezoelectric layer, and is not overlapped with the vertical projection of the first gap and the second gap in the piezoelectric layer; Wherein the width W of the heterostructure along the second direction is different from the sound velocity of the surface acoustic wave resonator and the sound velocity of the heterostructure V satisfies the relationship w=k × V is lambda/V, wherein lambda is the wavelength of the surface acoustic wave, V is the sound velocity of the piezoelectric layer material, K is an adjustment coefficient, and the value range of K is 0.8-1.2; the depth of the heterostructure along the thickness direction of the surface acoustic wave resonator comprises 0.3lambda-3lambda, wherein lambda is the wavelength of the surface acoustic wave, and the length of the heterostructure along the first direction is greater than the length of the surface acoustic wave resonator; a groove is formed in the surface, adjacent to the electrode layer, of the piezoelectric layer, a heterogeneous material layer is filled in the groove, and the heterogeneous structure comprises the heterogeneous material layer; The heterogeneous material layer is made of silicon dioxide or silicon nitride.
2. The surface acoustic wave resonator according to claim 1, characterized in that the heterostructure comprises a first heterostructure strip and a second heterostructure strip, The first heterogeneous strip is positioned below the first long finger, and the side surface of the first heterogeneous strip adjacent to the first gap is level with the top end of the first long finger far away from the first bus bar; the second heterogeneous strip is located below the second long finger, and the side surface, adjacent to the second gap, of the second heterogeneous strip is flush with the top end, away from the second bus bar, of the second long finger.
3. The surface acoustic wave resonator according to claim 1 or 2, characterized in that the heterostructure comprises a third heterostructure strip and a fourth heterostructure strip, The third heterogeneous bar is located below the second bus bar, and a side of the third heterogeneous bar adjacent to the second artificial finger is flush with an end of the second artificial finger adjacent to the second bus bar; The fourth heterogeneous bar is located below the first bus bar, and a side of the fourth heterogeneous bar adjacent to the first dummy finger is flush with an end of the first dummy finger adjacent to the first bus bar.
4. The surface acoustic wave resonator according to claim 1, characterized in that the surface of the piezoelectric layer adjacent to the electrode layer is provided with a cavity structure, the heterostructure comprising the cavity structure.
5. The surface acoustic wave resonator according to claim 1, characterized in that the surface of the piezoelectric layer adjacent to the electrode layer is provided with a doped region, the heterostructure comprising the piezoelectric layer doped with a set particle in the doped region.
6. The surface acoustic wave resonator according to claim 5, characterized in that the setting particles comprise vanadium or the setting particles comprise hydrogen and helium.
7. The surface acoustic wave resonator of claim 1, further comprising a temperature compensation layer and a substrate, the temperature compensation layer being located on a side of the electrode layer remote from the piezoelectric layer, the substrate being located on a side of the piezoelectric layer remote from the electrode layer.

Description

Surface acoustic wave resonator Technical Field The embodiment of the invention relates to the technical field of semiconductor packaging, in particular to a surface acoustic wave resonator. Background With the development of communication technology, the product terminal puts strict requirements on the performance of various devices, the filter is a key device of a communication system, with the development of technology, the variety of the filter is more and more, the technology from an LCR filter to a cavity filter, from an LTCC ceramic filter to a sound surface filter, the technology of the filter is continuously developed, and since the LTE era is entered, the function of the sound surface filter in the communication system is more and more important. Meanwhile, with the development of communication technology, various requirements on the filter are higher and higher, and particularly with the arrival of the fifth Generation mobile communication technology (5 th-Generation, 5G), the filter industry faces significant challenges and opportunities. The acoustic surface filter is widely applied to the front end of the radio frequency, has the advantages of low insertion loss, wide bandwidth, small volume and the like, but has various clutter modes, so that the performance of the filter is seriously affected, and the transverse mode is one of the main clutter modes, so that the suppression of the transverse mode has important significance for improving the performance of the acoustic surface filter. Disclosure of Invention The invention provides a surface acoustic wave resonator which can inhibit the transmission of a transverse mode, thereby improving the performance of a filter. The embodiment of the invention provides a surface acoustic wave resonator, which comprises: A piezoelectric layer; An electrode layer on the piezoelectric layer; The electrode layer comprises a transducer, wherein the transducer comprises a first bus bar, a first long finger, a first false finger, a second bus bar, a second long finger and a second false finger, wherein the first bus bar and the second bus bar extend along a first direction and are oppositely arranged, the first long finger, the second false finger, the second long finger and the first false finger extend along a second direction and are respectively positioned between the first bus bar and the second bus bar, the first long finger and the first false finger are alternately arranged along the first direction and are respectively connected with the first bus bar, the second long finger and the second false finger are alternately arranged along the first direction and are respectively connected with the second bus bar, the first long finger and the second false finger are oppositely arranged, a first gap is reserved between the first long finger and the second false finger, the second long finger and the first false finger are oppositely arranged, and the second long finger and the first false finger are alternately arranged along the first direction, and the second finger are mutually crossed along the second direction, and the second gap is reserved between the first long finger and the second finger; The piezoelectric layer includes at least one heterostructure having a depth greater than a thickness of the transducer, a propagation velocity of a surface acoustic wave in the heterostructure being different from a propagation velocity in the piezoelectric layer, the heterostructure extending along the first direction, the heterostructure overlapping a perpendicular projection of the transducer in the piezoelectric layer and not overlapping a perpendicular projection of the first gap and the second gap in the piezoelectric layer. Optionally, the heterostructure includes a first heterostructure stripe and a second heterostructure stripe, The first heterogeneous strip is positioned below the first long finger, and the side surface of the first heterogeneous strip adjacent to the first gap is level with the top end of the first long finger far away from the first bus bar; the second heterogeneous strip is located below the second long finger, and the side surface, adjacent to the second gap, of the second heterogeneous strip is flush with the top end, away from the second bus bar, of the second long finger. Optionally, the heterostructure includes a third heterostructure stripe and a fourth heterostructure stripe, The third heterogeneous bar is located below the second bus bar, and a side of the third heterogeneous bar adjacent to the second artificial finger is flush with an end of the second artificial finger adjacent to the second bus bar; The fourth heterogeneous bar is located below the first bus bar, and a side of the fourth heterogeneous bar adjacent to the first dummy finger is flush with an end of the first dummy finger adjacent to the first bus bar. Optionally, the surface of the piezoelectric layer adjacent to the electrode layer is provided with a cavity