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CN-121396131-B - Surface acoustic wave resonator

CN121396131BCN 121396131 BCN121396131 BCN 121396131BCN-121396131-B

Abstract

The application discloses a surface acoustic wave resonator, which comprises a piezoelectric substrate and an interdigital transducer arranged on the piezoelectric substrate. The interdigital transducer comprises a first bus bar and a second bus bar which are arranged in parallel, a first thickening layer which is arranged above the first bus bar vertically, and a second thickening layer which is arranged above the second bus bar vertically. Wherein a first end of the first thickening layer is aligned with an end of the first bus bar remote from the second bus bar and a second end of the second thickening layer is aligned with an end of the second bus bar remote from the first bus bar. The interdigital transducer further includes a first compensation layer disposed vertically above the first bus bar and a second compensation layer disposed vertically above the second bus bar, and a third end of the first compensation layer is aligned with an end of the first bus bar adjacent to the second bus bar, and a fourth end of the second compensation layer is aligned with an end of the second bus bar adjacent to the first bus bar.

Inventors

  • FENG DUAN
  • ZOU JIE
  • GENG DEQIANG

Assignees

  • 深圳新声半导体有限公司
  • 苏州新声科技有限公司

Dates

Publication Date
20260512
Application Date
20251225

Claims (14)

  1. 1. A surface acoustic wave resonator includes a piezoelectric substrate (100) and an interdigital transducer (200) provided on the piezoelectric substrate (100), characterized in that, The interdigital transducer (200) comprises a first bus bar (210) and a second bus bar (220) which are arranged in parallel, a first thickening layer (211) which is respectively arranged vertically above the first bus bar (210) and a second thickening layer (221) which is arranged vertically above the second bus bar (220), wherein A first end (2111) of the first thickening layer (211) is aligned with an end of the first bus bar (210) remote from the second bus bar (220), and a second end (2211) of the second thickening layer (221) is aligned with an end of the second bus bar (220) remote from the first bus bar (210); the interdigital transducer (200) further comprises a first compensation layer (212) disposed vertically above the first bus bar (210) and a second compensation layer (222) disposed vertically above the second bus bar (220), and The third end (2121) of the first compensation layer (212) is aligned with an end of the first bus bar (210) that is proximate to the second bus bar (220), and the fourth end (2221) of the second compensation layer (222) is aligned with an end of the second bus bar (220) that is proximate to the first bus bar (210).
  2. 2. A surface acoustic wave resonator according to claim 1, characterized in that the thickness of the first thickening layer (211) is greater than 0.7 μm and the thickness of the second thickening layer (221) is greater than 0.7 μm.
  3. 3. The surface acoustic wave resonator according to claim 2, characterized in that the thickness of the first compensation layer (212) is larger than 0.7 μm and the thickness of the second compensation layer (222) is larger than 0.7 μm.
  4. 4. The surface acoustic wave resonator according to claim 1, characterized in that the material of the first bus bar (210) is different from the material of the first thickening layer (211) and the first compensation layer (212), and The second bus bar (220) is of a material different from the material of the second thickening layer (221) and the second compensation layer (222).
  5. 5. A surface acoustic wave resonator according to claim 1, characterized in that the material of the first bus bar (210) is the same as the material of the first thickening layer (211) and the first compensation layer (212), and The material of the second bus bar (220) is the same as the material of the second thickening layer (221) and the second compensation layer (222).
  6. 6. The surface acoustic wave resonator according to claim 5, characterized in that the material of the first bus bar (210), the first thickening layer (211) and the first compensation layer (212) is aluminum, and the material of the second bus bar (220), the second thickening layer (221) and the second compensation layer (222) is aluminum.
  7. 7. The surface acoustic wave resonator according to claim 5, characterized in that the material of the first bus bar (210), the first thickening layer (211) and the first compensation layer (212) is copper, and the material of the second bus bar (220), the second thickening layer (221) and the second compensation layer (222) is copper.
  8. 8. The surface acoustic wave resonator according to claim 5, characterized in that the material of the first bus bar (210), the first thickening layer (211) and the first compensation layer (212) is platinum, and the material of the second bus bar (220), the second thickening layer (221) and the second compensation layer (222) is platinum.
  9. 9. The surface acoustic wave resonator according to claim 5, characterized in that the material of the first bus bar (210), the first thickening layer (211) and the first compensation layer (212) is gold, and the material of the second bus bar (220), the second thickening layer (221) and the second compensation layer (222) is gold.
  10. 10. The surface acoustic wave resonator according to claim 1, characterized in that the interdigital transducer (200) further comprises an interdigital electrode unit (230), wherein The interdigital electrode unit (230) includes a plurality of first electrode fingers (231) that are led out from the first bus bar (210) and extend toward the second bus bar (220), a plurality of second electrode fingers (232) that are led out from the second bus bar (220) and extend toward the first bus bar (210), a plurality of first dummy fingers (233) that are led out from the first bus bar (210) and are provided opposite to the opposite-side second electrode fingers (232), and a plurality of second dummy fingers (234) that are led out from the second bus bar (220) and are provided opposite to the opposite-side first electrode fingers (231).
  11. 11. The surface acoustic wave resonator according to claim 10, characterized in that the plurality of first electrode fingers (231) and the plurality of second electrode fingers (232) overlap each other and form an overlap region (235), wherein a boundary shape of the overlap region (235) conforms to a trigonometric function curve in a propagation direction of the acoustic wave, wherein the trigonometric function curve includes a sine function curve and a cosine function curve, and The shape of the first bus bar (210) and the second bus bar (220) matches the shape of the boundary of the overlap region (235).
  12. 12. The surface acoustic wave resonator according to claim 11, characterized in that the ratio between the minimum value of the longitudinal overlap length and the maximum value of the longitudinal overlap length of the plurality of first electrode fingers (231) and the plurality of second electrode fingers (232) is less than or equal to 40%.
  13. 13. A surface acoustic wave resonator according to claim 11, characterized in that the boundary length of the overlap region (235) is greater than or equal to 0.4 cycles of a trigonometric function curve.
  14. 14. The surface acoustic wave resonator according to claim 11, further comprising a first reflector (240) and a second reflector (250) disposed on opposite sides of the interdigital transducer (200), wherein The first reflector (240) comprises a third bus bar (241), a fourth bus bar (242) and a plurality of third electrode fingers (243) respectively connected with the third bus bar (241) and the fourth bus bar (242), and the second reflector (250) comprises a fifth bus bar (251), a sixth bus bar (252) and a plurality of fourth electrode fingers (253) respectively connected with the fifth bus bar (251) and the sixth bus bar (252); In the sound wave propagation direction, the shape of a third bus bar (241) corresponding to the first reflector (240) continues the shape of the first bus bar (210) and extends in the form of a trigonometric function curve, the shape of a fourth bus bar (242) corresponding to the first reflector (240) continues the shape of the second bus bar (220) and extends in the form of a trigonometric function curve, and In the sound wave propagation direction, the shape of a fifth bus bar (251) corresponding to the second reflector (250) continues the shape of the first bus bar (210) and extends in the form of a trigonometric function curve, and the shape of a sixth bus bar (252) corresponding to the second reflector (250) continues the shape of the second bus bar (220) and extends in the form of a trigonometric function curve.

Description

Surface acoustic wave resonator Technical Field The application relates to the technical field of surface acoustic wave devices, in particular to a surface acoustic wave resonator. Background Along with the development of 5G communication to high frequency and broadband, a surface acoustic wave resonator based on a piezoelectric film (such as a POI substrate) becomes a key technology due to the high Q value and the high coupling coefficient. However, due to the strong acoustic waveguide effect inherent to the thin film structure, the acoustic wave energy is highly concentrated in the thin film layer, resulting in that the energy is more likely to form parasitic standing waves, i.e., transverse modes, in the saw resonator aperture in a direction perpendicular to the main propagation direction. These transverse modes can introduce spurious peaks in the frequency spectrum that affect the pass band flatness, out-of-band rejection and insertion loss of the filter, ultimately degrading the overall performance of the filter. Existing methods of suppressing the transverse mode reduce the acoustic wave propagation velocity in the busbar region by adding a mass load to the busbar of the interdigital transducer. Therefore, the transverse mode can leak out through the bus bar, and further the suppression of the transverse mode in the surface acoustic wave resonator is realized. However, when a mass load is added to the bus bar, the actual width of the mass load is smaller than the design value due to process limitations (e.g., photolithography and etching), and the shrinkage occurs, thereby affecting the suppression capability for the transverse mode, and further reducing the resonance performance of the surface acoustic wave resonator. The publication number is CN120415366A, and the name is a surface acoustic wave resonator and an electronic device. The interdigital transducer comprises two outer bus bars which are oppositely arranged, and at least two inner bus bars which are oppositely arranged, wherein the inner bus bars are arranged between the outer bus bars, the outer bus bars and the inner bus bars are parallel to the length direction, the inner bus bars are provided with a plurality of first protruding parts which protrude out of the edges of the inner bus bars along the width direction, the plurality of first protruding parts are arranged along the length direction, an inner layer edge sound velocity zone is formed on at least one side of the inner bus bars based on the first protruding parts, an inner layer sound velocity zone is formed on the inner layer bus bars, and the sound velocity of the inner layer edge sound velocity zone is smaller than that of the inner layer sound velocity zone. The sawtooth structure formed by the plurality of first protruding parts can enable sound waves to diffuse and reflect in the transverse propagation, so that the Q value of a transverse clutter mode is reduced, and the generation of a transverse mode is effectively restrained. The publication number is CN119628595A, and the name is a surface acoustic wave resonator and a filter. The device comprises an interdigital structure, a reflection grid, a first finger and a second finger, wherein the interdigital structure comprises a first interdigital area and a second interdigital area, the first interdigital area comprises a plurality of first fingers and the second interdigital area comprises a plurality of second fingers, the reflection grid is arranged on two sides of the interdigital structure in a first direction, the reflection grid is positioned on the same plane with the first fingers and the second fingers, the reflection grid is mutually perpendicular to the first fingers, each first finger is oppositely arranged with each second finger in the first direction, gaps are formed between the first fingers and the second fingers, the first fingers are arranged in parallel in the second direction, and the first direction is perpendicular to the second direction. Aiming at the technical problem that the transverse mode in the surface acoustic wave resonator is not effectively restrained, so that the performance of the surface acoustic wave resonator is affected in the prior art, no effective solution is proposed at present. Disclosure of Invention The disclosure provides a surface acoustic wave resonator to at least solve a technical problem that a transverse mode in the surface acoustic wave resonator is not effectively inhibited, thereby affecting performance of the surface acoustic wave resonator in the prior art. According to one aspect of the present application, there is provided a surface acoustic wave resonator including a piezoelectric substrate and an interdigital transducer provided on the piezoelectric substrate. The interdigital transducer comprises a first bus bar and a second bus bar which are arranged in parallel, a first thickening layer which is arranged above the first bus bar vertically, and a second thi