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CN-114696766-B - Film bulk acoustic resonator and preparation method thereof

CN114696766BCN 114696766 BCN114696766 BCN 114696766BCN-114696766-B

Abstract

The application provides a film bulk acoustic resonator and a preparation method thereof, wherein the method comprises the steps of providing a stripping substrate, and preparing a piezoelectric film stacking structure with at least one elastic connection structure on the stripping substrate; providing a substrate with a cavity; placing the piezoelectric film stack structure in a cavity of the substrate, and fixedly connecting at least one elastic connection structure of the piezoelectric film stack with the substrate; the application solves the problem that the film bulk acoustic resonator in the related technology breaks at the bonding connection position of the piezoelectric film stacking structure and the substrate, and improves the structural stability of the resonator.

Inventors

  • NIU YUJIAO
  • ZHANG SHUMIN

Assignees

  • 杭州左蓝微电子技术有限公司

Dates

Publication Date
20260505
Application Date
20201225

Claims (11)

  1. 1. A method of making a thin film bulk acoustic resonator, the method comprising: Providing a peeling substrate, and preparing a piezoelectric film stacking structure with at least one elastic connection structure on the peeling substrate; Providing a substrate with a cavity; Placing the piezoelectric film stack structure in a cavity of the substrate, and fixedly connecting at least one elastic connection structure of the piezoelectric film stack with the substrate; peeling the peeled substrate to form a film bulk acoustic resonator; wherein, prepare the piezoelectric film stack structure with at least one elastic connection structure on the said stripping base plate, comprising: Providing the stripping substrate, and coating a photoetching layer on the stripping substrate; Etching the photoetching layer to form a plurality of photoetching bulges in a preset area on the stripping substrate; Sequentially depositing a first electrode layer, a piezoelectric layer and a second electrode layer on the stripping substrate with the plurality of photoetching bulges to form at least one elastic connection structure on the plurality of photoetching bulges so as to obtain the piezoelectric film stacking structure with the at least one elastic connection structure; And etching a plurality of photoetching bulges in the piezoelectric film stacking structure to obtain the film bulk acoustic resonator.
  2. 2. The method of manufacturing a thin film bulk acoustic resonator according to claim 1, wherein providing a substrate with a cavity comprises: providing a silica layer having oppositely disposed first and second faces; depositing a first insulating layer on a first side of the silicon dioxide layer and depositing a second insulating layer on a second side of the silicon dioxide layer; etching the second insulating layer according to a preset size to form a cavity in the second insulating layer; and depositing a metal layer on the surface of the second insulating layer with the cavity to obtain the substrate with the cavity.
  3. 3. The method of manufacturing a thin film bulk acoustic resonator according to any of claims 1-2, characterized in that providing a release substrate on which a piezoelectric thin film stack structure with at least one elastic connection structure is manufactured comprises: Providing the stripping substrate, and depositing a buffer layer on the stripping substrate; and preparing the piezoelectric film stacking structure with at least one elastic connection structure on the buffer layer.
  4. 4. The method of manufacturing a thin film bulk acoustic resonator according to claim 1, wherein the plurality of lithography protrusions comprise hemispherical, triangular, cylindrical or rectangular parallelepiped shapes.
  5. 5. The method of manufacturing a thin film bulk acoustic resonator according to claim 1, wherein the at least one elastic connection structure is integrally formed with the first electrode layer and/or the at least one elastic connection structure is integrally formed with the second electrode.
  6. 6. A thin film bulk acoustic resonator, wherein the resonator is prepared by a method for preparing a thin film bulk acoustic resonator according to any one of claims 1 to 5, the resonator comprising: a substrate with a cavity and a piezoelectric film stack structure with at least one elastic connection structure; The piezoelectric film stacking structure is arranged on the cavity of the substrate, and at least one elastic connecting structure of the piezoelectric film stacking structure is fixedly connected with the substrate.
  7. 7. The thin film bulk acoustic resonator according to claim 6, wherein the piezoelectric thin film stack structure comprises: The piezoelectric device comprises a first electrode layer, a piezoelectric layer, a second electrode layer and at least one elastic connecting structure; The piezoelectric layer is positioned between the first electrode layer and the second electrode layer, and the first electrode layer and the second electrode layer are oppositely arranged; The at least one elastic connection structure is used for fixedly connecting the piezoelectric film stacking structure with the substrate.
  8. 8. The thin film bulk acoustic resonator of claim 7, wherein the at least one elastic connection structure is integrally formed with the first electrode layer and/or the at least one elastic connection structure is integrally formed with the second electrode.
  9. 9. The thin film bulk acoustic resonator of claim 7, wherein the shape of the at least one elastic connection structure comprises a dogleg, square wave, Ω, or spring shape.
  10. 10. The thin film bulk acoustic resonator of claim 7, wherein the substrate comprises: A first insulating layer, a silicon oxide layer, a second insulating layer, and a metal layer; and a cavity is arranged in the second insulating layer and the metal layer, so that the piezoelectric film stacking structure is arranged on the cavity, and the first electrode layer and/or the second electrode layer are/is fixedly connected with the metal layer through the at least one elastic connecting structure.
  11. 11. The thin film bulk acoustic resonator of any of claims 6-10, wherein the at least one elastic connection structure comprises one or a combination of tungsten, molybdenum, platinum, ruthenium, iridium, titanium tungsten, aluminum.

Description

Film bulk acoustic resonator and preparation method thereof Technical Field The application relates to the technical field of communication filtering, in particular to the technical field of resonant filtering, and in particular relates to a film bulk acoustic resonator and a preparation method thereof. Background With the development of wireless communication applications, the requirements of data transmission speed are increasing. In the field of mobile communication, the first generation communication technology is an analog technology, the second generation communication technology realizes digital voice communication, the third generation communication technology is characterized by multimedia communication, the fourth generation communication technology improves the communication rate to 1Gbps, the time delay is reduced to 10ms, the fifth generation communication technology is a new generation mobile communication technology after the fourth generation communication technology, and the fifth generation communication technology aims to solve the communication between people and objects except people and between objects and realize the wish of 'everything interconnection'. The increase in data rate corresponds to the high utilization of spectrum resources and the complexity of communication protocols. Because of the limited frequency spectrum, the frequency spectrum must be fully utilized in order to meet the requirement of the data rate, and meanwhile, in order to meet the requirement of the data rate, a carrier aggregation technology is also used from the fourth generation communication technology, so that one device can simultaneously transmit data by utilizing different carrier frequency spectrums. On the other hand, in order to support a sufficient data transmission rate within a limited bandwidth, communication protocols are becoming more and more complex, and thus strict demands are also being made on various performances of radio frequency systems. The most prevalent implementations of radio frequency filters are surface acoustic wave filters and filters based on thin film bulk acoustic resonator technology. The SAW filter is suitable for use below 1.5GHz due to its own limitations. However, current wireless communication protocols have long used frequency bands greater than 2.5GHz, where filters based on thin film bulk acoustic resonator technology must be used. The main components in the film bulk acoustic wave resonator are film bulk acoustic wave resonators, there is a film bulk acoustic wave resonator in the related art which includes a substrate having a groove structure and a piezoelectric film stack structure having an upper electrode, a piezoelectric film, and a lower electrode, the upper electrode and the lower electrode being bonded with a bonding layer on a substrate layer, so that the piezoelectric film stack structure is disposed above the groove structure, thereby forming a cavity structure on the substrate. The piezoelectric film stacking structure in the related art is anchored on the substrate layer, and the anchoring is performed in a widening and thickening mode of the electrode in the related art, but the inventor finds that anchoring energy loss (anchor loss) exists at the anchoring position through researches, on one hand, sound waves can leak through the anchoring position, and on the other hand, the self gravity of the piezoelectric film stacking structure is overcome only through supporting force of the bonding position, so that the piezoelectric film stacking structure is suspended above the cavity, when the film bulk acoustic resonator realizes the conversion of sound waves and electric signals, the piezoelectric film stacking structure can vibrate up and down, stress of the bonding connection position is increased, and the phenomenon that the bonding connection position breaks exists, so that the stability of the resonator is influenced. It should be noted that the description of the background art does not constitute prior art to which the present application pertains and does not constitute a limitation on the scope of application. For example, the application can be applied to the field of mobile communication and other fields requiring radio frequency such as WIFI. Disclosure of Invention Aiming at the defects in the related art, the film bulk acoustic resonator and the preparation method thereof provided by the application solve the problem that the film bulk acoustic resonator in the related art breaks at the bonding connection position of the piezoelectric film stacking structure and the substrate, and improve the structural stability of the resonator. In a first aspect, the application provides a method for preparing a film bulk acoustic resonator, which comprises the steps of providing a stripping substrate, preparing a piezoelectric film stack structure with at least one elastic connection structure on the stripping substrate, providing a substrate with a c