Film bulk acoustic resonator for suppressing side energy radiation based on photonic crystal

A thin-film bulk acoustic wave and phononic crystal technology, applied in electrical components, impedance networks, etc., can solve problems such as quality factor reduction and resonator energy loss, and achieve the effect of improving quality factor and solving side energy leakage

Active Publication Date: 2021-09-24
UNIV OF ELECTRONIC SCI & TECH OF CHINA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Nevertheless, the phenomenon of side leakage still occurs between two adjacent transverse broadband piston

Method used

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  • Film bulk acoustic resonator for suppressing side energy radiation based on photonic crystal
  • Film bulk acoustic resonator for suppressing side energy radiation based on photonic crystal
  • Film bulk acoustic resonator for suppressing side energy radiation based on photonic crystal

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0048] This embodiment provides a transversely excited thin-film bulk acoustic resonator. On the basis of the SMR Bragg reflection structure, a phononic crystal is used as a side energy radiation suppression structure to obtain a high-quality factor resonator with an operating frequency of 3.6GHz to 4.4GHz. ; Specific structure such as Figure 1 to Figure 7 As shown, it includes: a substrate 202, a high acoustic impedance film 204, a low acoustic impedance film 203, and a piezoelectric film 201 stacked sequentially on the substrate, an interdigital transducer set on the piezoelectric film, and a grounding protection electrode 104;

[0049] The interdigital transducer is located at the center of the upper surface of the piezoelectric film 201, and is composed of input electrodes 101 and output electrodes 103 intersected to form, and is used to realize the electrical signal input and output during the electromechanical conversion process of the piezoelectric film 201, and the inp...

Embodiment 2

[0056] This embodiment provides a transversely excited thin-film bulk acoustic resonator. On the basis of the SMR Bragg reflection structure, a phononic crystal is used as a side energy radiation suppression structure to obtain a high-quality factor resonator with an operating frequency of 3.6GHz to 4.4GHz. ; Specific structure such as Figure 12 to Figure 14 Shown, its only difference with embodiment 1 is:

[0057] The phononic crystal is composed of several unit structures arranged in an array, and the unit structures are as follows Figure 15 As shown, specifically, it is a circular metal pillar arranged on the upper surface of the piezoelectric film 201. The material of the circular metal pillar is platinum, the array size is 10×3, the cell size is a2 equal to 0.3um, d equal to 0.25um, and hPt is 0.23um and hLN are equal to 502nm; the bandgap diagram of this phononic crystal is as Figure 16 As shown, it can be seen from the figure that the phononic crystal has a local b...

Embodiment 3

[0060] This embodiment provides a transversely excited film bulk acoustic resonator. On the basis of the Freestanding structure, a phononic crystal is used as a side energy radiation suppression structure to obtain a high quality factor resonator. Its structure is as follows Figure 19 As shown, it specifically includes: a substrate 202, a piezoelectric film 201 provided on the substrate, an interdigital transducer provided on the piezoelectric film, and a grounding guard electrode 104;

[0061] A back cavity is provided at the bottom of the substrate 202, located directly below the IDT;

[0062] The interdigital transducer is located at the center of the upper surface of the piezoelectric film 201, and is composed of input electrodes 101 and output electrodes 103 intersected to form, and is used to realize the electrical signal input and output during the electromechanical conversion process of the piezoelectric film 201, and the input electrodes 101 can convert electrical en...

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Abstract

The invention belongs to the technical field of a radio frequency micro electro mechanical system, relates to a transverse excitation film bulk acoustic resonator, and particularly provides a film bulk acoustic resonator for suppressing side energy radiation based on a photonic crystal, which is used for solving the problem of side energy leakage of an existing transverse excitation film bulk acoustic resonator at a suspension beam tether. On the basis of a broadband piston mode resonator with a Freestanding type structure or an SMR Bragg reflection structure, a photonic crystal is introduced between an electrode finger strip of an interdigital transducer and a broadband piston structure to serve as a side energy radiation suppression structure; and a specific unit structure of the photonic crystal is designed in a matched manner, namely a cross-shaped hole penetrating through the piezoelectric film or a circular metal column arranged on the piezoelectric film, so that sound wave energy is restrained in an interdigital electrode pair resonant cavity, the problem of side energy leakage is solved, the in-band quality factor is remarkably improved. Therefore, the resonator is especially suitable for being made into a 5G frequency band (high-frequency large-bandwidth frequency bands such as N77, N78 and N79) high-quality-factor filter.

Description

technical field [0001] The invention belongs to the technical field of radio-frequency micro-electromechanical systems, and relates to a transversely excited thin-film bulk acoustic resonator, in particular to a high-quality-factor thin-film bulk acoustic wave resonator based on phononic crystals to suppress side energy radiation. Background technique [0002] In recent years, rotating Y-cut lithium niobate LiNbO 3 (LN) A1-type Lamb wave resonators on piezoelectric substrates have attracted much attention for use in the 5G frequency band; in this type of resonator, a solid-state The assembly structure (SMR type) or the direct use of the air cavity (Freestanding type) will have a certain limit on the energy of the resonator, and between the fingertips of the interdigitated electrodes and the electrode busbar, between the resonator and the peripheral protective grounding metal Placing the transverse broadband piston structure and the longitudinal broadband piston structure (e...

Claims

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Application Information

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IPC IPC(8): H03H9/02H03H9/58
CPCH03H9/02039H03H9/02062H03H9/02118H03H9/582
Inventor 鲍景富龚柯源李亚伟梁起吴兆辉
Owner UNIV OF ELECTRONIC SCI & TECH OF CHINA
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