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CN-122026851-A - Novel coupling mode acoustic wave resonator and filter

CN122026851ACN 122026851 ACN122026851 ACN 122026851ACN-122026851-A

Abstract

The application discloses a novel coupling mode acoustic wave resonator and a filter, which comprise a substrate; the electrode comprises a substrate, a piezoelectric layer arranged on one side surface of the substrate, and an interdigital electrode arranged on one side of the piezoelectric layer away from the substrate. The piezoelectric coefficient of the piezoelectric layer comprises an e 11 component, an e 13 component, an e 31 component and an e 33 component in a piezoelectric coefficient matrix by selecting the material of the piezoelectric layer and setting the value range of an in-plane Euler angle alpha, and longitudinal waves with two mutually perpendicular polarization directions are coupled together by designing the ratio of the thickness of the piezoelectric layer to the periodic wavelength of the interdigital electrode and the ratio of the thickness of the interdigital electrode to the periodic wavelength of the interdigital electrode to form a novel coupling mode sound wave with a polarization direction forming a certain included angle with the plane of the piezoelectric layer. The included angle is more than 0 degrees and less than 90 degrees. The application provides a solution for the high-frequency large-bandwidth acoustic wave filter, has simple device structure and reduces the complexity and cost of device preparation.

Inventors

  • ZUO CHENGJIE
  • DONG JIAXIN
  • DAI ZHONGBIN

Assignees

  • 中国科学技术大学

Dates

Publication Date
20260512
Application Date
20260203

Claims (10)

  1. 1. A novel coupled mode acoustic wave resonator, comprising: A substrate; A piezoelectric layer provided on a surface of one side of the substrate; The interdigital electrode is arranged on one side of the piezoelectric layer, which is away from the substrate; The piezoelectric material is an anisotropic piezoelectric material, the piezoelectric coefficient of the piezoelectric layer comprises an e 11 component, an e 13 component, an e 31 component and an e 33 component in a piezoelectric coefficient matrix by setting an in-plane Euler angle alpha of the piezoelectric material, wherein the in-plane Euler angle alpha of the piezoelectric material refers to an included angle formed by a direction perpendicular to the length direction of an interdigital electrode and the positive direction of an X axis under a global coordinate system of the piezoelectric material, and the piezoelectric coefficient matrix is expressed as: ; By designing the ratio h 1 /lambda of the thickness h 1 of the piezoelectric layer to the periodic wavelength lambda of the interdigital electrode, a transverse electric field and a longitudinal electric field simultaneously exist in the piezoelectric layer when voltage is applied to the interdigital electrode, a transverse electric field excitation e 11 component and a longitudinal electric field excitation e 31 component simultaneously generate longitudinal waves which propagate along the direction x perpendicular to the length direction of the interdigital electrode and parallel to the plane of the piezoelectric layer, and a transverse electric field excitation e 13 component and a longitudinal electric field excitation e 33 component simultaneously generate longitudinal waves which propagate along the direction Z perpendicular to the plane of the piezoelectric layer; Through designing the ratio h IDT /lambda of the thickness h IDT of the interdigital electrode and the periodic wavelength lambda of the interdigital electrode, longitudinal waves with two mutually perpendicular polarization directions are coupled together to form a novel coupling mode sound wave with a polarization direction and a plane where the piezoelectric layer is positioned forming a certain included angle beta, and the included angle beta is 0-90 degrees.
  2. 2. The novel coupling mode acoustic wave resonator of claim 1, wherein the ratio of the piezoelectric layer thickness h 1 to the interdigital electrode periodic wavelength λ, h 1 /λ, is 0.3 to 0.6.
  3. 3. The novel coupling mode acoustic wave resonator of claim 1, wherein the ratio of the interdigital electrode thickness h IDT to the interdigital electrode periodic wavelength λ, h IDT /λ, is 0.05 to 0.25.
  4. 4. The novel coupling mode acoustic wave resonator according to claim 1, wherein the number of the interdigital electrodes is 2 to 500, the width of the interdigital electrodes is 0.001 to 5 μm, and the length of the interdigital electrodes is 1 to 500 μm.
  5. 5. The novel coupling mode acoustic wave resonator according to claim 1, wherein the piezoelectric layer is any one of a single lithium niobate layer, a multi-layered lithium niobate layer, a single lithium tantalate layer, a multi-layered lithium tantalate layer, or a composite layer composed of a lithium niobate layer and a lithium tantalate layer; The thickness of the piezoelectric layer is 10nm to 5000: 5000 nm; The substrate is one or more of a silicon carbide substrate, a sapphire substrate, a diamond substrate, a gallium nitride substrate or a silicon substrate; the interdigital electrode is made of any one of aluminum, platinum, gold, silver, copper, tungsten, molybdenum, chromium, nickel, titanium gold, titanium aluminum, chromium gold or chromium aluminum.
  6. 6. The novel coupling mode acoustic wave resonator according to claim 1, wherein the piezoelectric layer is 36 ° Y tangential lithium niobate, and the euler angle α has a value in the range of 23 ° or more and less α or less 157 ° or-157 ° or less α or less than-23 °.
  7. 7. The novel coupling mode acoustic wave resonator according to claim 1, wherein the piezoelectric layer is 36 ° Y tangential lithium tantalate, and the euler angle α has a value in the range of 33 ° or less α or 147 ° or-147 ° or α or-33 °.
  8. 8. The novel coupling mode acoustic wave resonator of claim 1, further comprising a dielectric layer between the piezoelectric layer and the substrate; The dielectric layer is one or more of a silicon dioxide layer, a polysilicon layer or a silicon nitride layer; The dielectric layer has a thickness of 10nm to 5000 a nm a.
  9. 9. The novel coupling mode acoustic wave resonator of claim 8, wherein the thickness of the dielectric layer is less than or equal to the thickness of the piezoelectric layer.
  10. 10. A filter comprising a novel coupled mode acoustic wave resonator as claimed in any one of claims 1 to 9.

Description

Novel coupling mode acoustic wave resonator and filter Technical Field The application relates to the technical field of acoustic wave resonators, in particular to a novel coupling mode acoustic wave resonator and a filter. Background With the rapid development of fifth generation (5G) and future sixth generation (6G) mobile communication technologies, wireless communication systems have shown explosive growth in demand for data transmission rates and capacities. To meet this demand, the communication spectrum is expanding from the traditional sub-6 GHz band to the higher centimeter (7-24 GHz) or even millimeter wave band. However, the increase of the operating frequency brings a serious challenge to the rf front-end module. In a complex electromagnetic environment, the filter in the rf front-end module plays the role of the "traffic police", whose core function is to select signals in the desired frequency band and suppress out-of-band interference. Acoustic wave filters, including Surface Acoustic Wave (SAW) and Bulk Acoustic Wave (BAW) filters, have long been the mainstay of choice for mobile communication radio frequency front-ends due to their high Q and miniaturization advantages. In the centimeter wave band, in order to support high-speed data transmission, an acoustic wave filter is required to have a wide bandwidth while operating at a high frequency. Acoustic wave filters are typically composed of acoustic wave resonators, and thus the need for high frequency, large bandwidth acoustic wave filters is essentially a requirement for acoustic wave resonators having high resonant frequencies and large electromechanical coupling coefficients. However, existing acoustic wave filtering techniques face fundamental bottlenecks as frequencies rise to the centimeter wave band and require large bandwidths. For example, the conventional Film Bulk Acoustic Resonator (FBAR) resonance frequency is determined by the thickness of the piezoelectric film, and an extremely thin piezoelectric film must be used in order to achieve a higher center frequency, which increases process difficulty and reduces device reliability. In addition, the electromechanical coupling coefficient (k 2) of aluminum nitride (AlN) films used in conventional FBARs is limited, although the industry has increased the coupling coefficient by using Sc-doped AlN, this tends to be at the expense of material performance and process maturity, and the increase in amplitude still appears to be a forever in the face of future >8 GHz band and large relative bandwidth requirements. Therefore, a brand new acoustic resonator is urgently needed in the art, which can break through the frequency and bandwidth barriers of the existing acoustic technology and realize high working frequency and large bandwidth at the same time in the centimeter wave frequency band, so as to provide a core radio frequency front-end filtering solution for next-generation wireless communication equipment. Disclosure of Invention In view of the above, the application provides a novel coupling mode acoustic wave resonator, which has a simple device structure and can reduce the complexity and cost of device preparation. The application provides a novel coupling mode acoustic wave resonator, which comprises the following components: A substrate; A piezoelectric layer provided on a surface of one side of the substrate; The interdigital electrode is arranged on one side of the piezoelectric layer, which is away from the substrate; The piezoelectric layer is made of anisotropic piezoelectric material, and the piezoelectric coefficients of the piezoelectric layer comprise an e 11 component, an e 13 component, an e 31 component and an e 33 component in a piezoelectric coefficient matrix by setting an in-plane Euler angle alpha of the piezoelectric material; The in-plane Euler angle alpha of the piezoelectric material is an included angle formed by a direction perpendicular to the length direction of the interdigital electrode and the positive X-axis direction of the global coordinate system of the piezoelectric material in the plane of the piezoelectric layer, and the piezoelectric coefficient matrix is expressed as follows: ; By designing the ratio h 1/lambda of the thickness h 1 of the piezoelectric layer to the periodic wavelength lambda of the interdigital electrode, a transverse electric field and a longitudinal electric field simultaneously exist in the piezoelectric layer when voltage is applied to the interdigital electrode, a transverse electric field excitation e 11 component and a longitudinal electric field excitation e 31 component simultaneously generate longitudinal waves which propagate along the direction x perpendicular to the length direction of the interdigital electrode and parallel to the plane of the piezoelectric layer, and a transverse electric field excitation e 13 component and a longitudinal electric field excitation e 33 component simultaneously generate longitudi