CN116961617A - FBAR resonator capable of improving Q value - Google Patents
FBAR resonator capable of improving Q value Download PDFInfo
- Publication number
- CN116961617A CN116961617A CN202310720317.1A CN202310720317A CN116961617A CN 116961617 A CN116961617 A CN 116961617A CN 202310720317 A CN202310720317 A CN 202310720317A CN 116961617 A CN116961617 A CN 116961617A
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- electrode
- fbar
- resonator
- value
- thin film
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- 239000010409 thin film Substances 0.000 claims abstract description 12
- 239000000758 substrate Substances 0.000 claims abstract description 10
- 239000010408 film Substances 0.000 claims abstract description 9
- 239000007787 solid Substances 0.000 claims description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 3
- 238000005530 etching Methods 0.000 claims description 3
- 239000002184 metal Substances 0.000 claims description 3
- 229910052751 metal Inorganic materials 0.000 claims description 3
- 229910052710 silicon Inorganic materials 0.000 claims description 3
- 239000010703 silicon Substances 0.000 claims description 3
- 230000008859 change Effects 0.000 abstract description 5
- 230000000694 effects Effects 0.000 description 4
- 230000008878 coupling Effects 0.000 description 3
- 238000010168 coupling process Methods 0.000 description 3
- 238000005859 coupling reaction Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000000306 component Substances 0.000 description 1
- 239000008358 core component Substances 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000003071 parasitic effect Effects 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 230000001902 propagating effect Effects 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
Classifications
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
- H03H9/17—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator
- H03H9/171—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator implemented with thin-film techniques, i.e. of the film bulk acoustic resonator [FBAR] type
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/02007—Details of bulk acoustic wave devices
- H03H9/02086—Means for compensation or elimination of undesirable effects
- H03H9/0211—Means for compensation or elimination of undesirable effects of reflections
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/125—Driving means, e.g. electrodes, coils
- H03H9/13—Driving means, e.g. electrodes, coils for networks consisting of piezoelectric or electrostrictive materials
- H03H9/132—Driving means, e.g. electrodes, coils for networks consisting of piezoelectric or electrostrictive materials characterized by a particular shape
Landscapes
- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)
Abstract
The invention provides an FBAR resonator for improving Q value, which comprises the following components: the piezoelectric thin film comprises a substrate, a Bragg reflection layer, two electrodes and a piezoelectric thin film; the Bragg reflection layer is paved on the upper surface of the substrate; the upper surface of the Bragg reflection layer is connected with one electrode; a piezoelectric film layer is arranged between the electrode and the other electrode. The electrode shape is designed into a gradient consistent with the speed change of the sound wave, the difference of the sound wave speed in different directions is also presented, the distance between the center of the electrode and the edge is also presented, the time for the sound wave to reach the edge is ensured to be the same, thereby forming effective reflection and improving the Q value.
Description
Technical Field
The invention relates to the field of resonators, in particular to an FBAR resonator for improving a Q value.
Background
FBAR (FilmBulkAcousticResonator) is a microwave filter based on frequency selection of bulk acoustic waves, which converts electrical energy (signals) into acoustic waves using the inverse piezoelectric effect of a piezoelectric film, thereby forming resonance. When an alternating voltage is applied to the electrodes of the FBAR, the electric field generates a piezoelectric effect, thereby creating mechanical vibration between the membrane and the piezoelectric material. Such mechanical vibrations will cause acoustic resonances within the FBAR, the resonance characteristics depending on the size, shape and material properties of the FBAR. The core component of the FBAR is a sandwich structure consisting of a top electrode, a piezoelectric layer and a bottom electrode. When a voltage is applied to the electrodes, bulk acoustic waves propagating in the direction perpendicular to the electrodes are reflected at the surfaces of the upper and lower electrodes and confined in a sandwich structure to form standing wave resonances. Besides the longitudinal vibration main mode, other transverse stray vibration modes exist in the actual FBAR device, energy loss can be caused by the generation of the transverse stray modes, the Q value of the device is reduced, and meanwhile fluctuation in the passband of the FBAR filter can be caused, so that the filtering performance is affected. While the shape of the FBAR electrode is closely related to the energy coupling and distribution characteristics.
Disclosure of Invention
In view of the above, the present invention has been made to provide an improved Q-value FBAR resonator that overcomes or at least partially solves the above-mentioned problems.
According to an aspect of the present invention, there is provided an FBAR resonator for improving a Q value, the resonator comprising: the piezoelectric thin film comprises a substrate, a Bragg reflection layer, two electrodes and a piezoelectric thin film;
the Bragg reflection layer is laid on the upper surface of the substrate
The upper surface of the Bragg reflection layer is connected with one electrode;
a piezoelectric film layer is arranged between the electrode and the other electrode.
And the electrode has a gradual electrode edge shape consistent with the speed gradient of the sound wave.
Optionally, the shape of the electrode is: triangle, pentagon, circle.
Optionally, the structural type of the resonator includes: air gap type, silicon back side etching type, and solid state assembly type.
Optionally, the piezoelectric film is a ZnO film.
Optionally, the electrode specifically includes: metal electrodes Mo, W, al.
The invention provides an FBAR resonator for improving Q value, which comprises the following components: the piezoelectric thin film comprises a substrate, a Bragg reflection layer, two electrodes and a piezoelectric thin film; the Bragg reflection layer is paved on the upper surface of the substrate; the upper surface of the Bragg reflection layer is connected with one electrode; a piezoelectric film layer is arranged between the electrode and the other electrode. The electrode shape is designed into a gradient consistent with the speed change of the sound wave, the difference of the sound wave speed in different directions is also presented, the distance between the center of the electrode and the edge is also presented, the time for the sound wave to reach the edge is ensured to be the same, thereby forming effective reflection and improving the Q value.
The foregoing description is only an overview of the present invention, and is intended to be implemented in accordance with the teachings of the present invention in order that the same may be more clearly understood and to make the same and other objects, features and advantages of the present invention more readily apparent.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of an FBAR resonator with improved Q-value according to an embodiment of the present invention;
FIG. 2 is a schematic diagram illustrating an example of the shape of a triangular electrode according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of sound velocity profiles in different directions according to an embodiment of the present invention;
fig. 4 is a schematic view of an electrode shape according to an embodiment of the present invention.
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
The terms "comprising" and "having" and any variations thereof in the description embodiments of the invention and in the claims and drawings are intended to cover a non-exclusive inclusion, such as a series of steps or elements.
The technical scheme of the invention is further described in detail below with reference to the accompanying drawings and the examples.
As shown in fig. 1, an FBAR resonator for increasing Q value, the resonator comprising: the piezoelectric thin film comprises a substrate, a Bragg reflection layer, two electrodes and a piezoelectric thin film; the Bragg reflection layer is paved on the upper surface of the substrate; the upper surface of the Bragg reflection layer is connected with one electrode; a piezoelectric film layer is arranged between the electrode and the other electrode.
The FBAR has the advantages of small volume, low loss, integration and the like, and is widely applied to the fields of communication, radio, radar and the like. The Q value (quality factor) is an important measure of its performance, and a high Q value indicates that the FBAR has better selectivity and lower signal loss. Therefore, it is necessary to increase the Q value of the FBAR.
There are three main types of conventional FBAR structures: air gap type, silicon back side etching type, and solid state assembly type. The following figures show cross-sectional views of solid state assembled FBARs, as exemplified by (other types are applicable). The piezoelectric film (such as ZnO) is clamped between metal electrodes (such as Mo, W and Al) to form a basic sandwich structure, and the design of the invention is mainly to improve the performance of the resonator by changing the shape of two layers of electrodes.
Different electrode shapes have different effects on energy coupling, energy portion and energy loss, and thus Q value. Common shapes for the electrode shapes are square, pentagon, triangle, circle. The traveling acoustic wave propagates between the parallel electrodes and is reflected multiple times at the edges of the electrodes, eventually returning to the same point, thereby creating an unwanted mode, i.e., a spurious mode, which degrades the performance of the device. To suppress the generation of spurious modes, FBAR devices are designed with non-uniform edges, such as triangular, pentagonal, and circular, and gradually changed electrode edge shapes, such as the triangular electrode shape structure shown in fig. 2. The invention proposes to use an edge-shaped electrode design that varies according to the speed characteristics to further improve the resonance characteristics.
As shown in fig. 3, since three kinds of sound waves independent of each other exist simultaneously in a specific direction, their polarization directions are perpendicular to each other and have different speeds. In addition to the fast shear wave, the propagation speeds of the quasi-longitudinal wave and the slow shear wave are changed along with the change of the propagation direction, so that the arrival time of the quasi-longitudinal wave and the slow shear wave at the edge is different under the excitation of signals.
The invention proposes that the shape of the electrode edge is designed to be a gradient characteristic consistent with the speed change, so that sound waves in all directions reach the edge at the same time to form effective reflection, enhance energy coupling and further improve the Q value. As shown in fig. 4, the electrode shape is shown as an example, and in practice, the electrode design should be adjusted according to the final acoustic velocity in each direction to achieve the best reflection effect.
The electrode edge design is unreasonable, the parasitic modulus can be very large, can influence the planarization of resonance curve, and can increase the loss. The choice of a suitable electrode shape is critical to the resonator performance. This patent selects suitable electrode shape to the suppression of FBAR transverse spurious modes to improve resonator performance. The invention proposes to design the electrode shape as a gradient consistent with the speed change of the sound wave, as shown in the following figure 4, the distance between the center of the electrode and the edge is also different corresponding to the difference of the speed of the sound wave in different directions in figure 3, and the time for the sound wave to reach the edge is ensured to be the same, thereby forming effective reflection and improving the Q value.
The beneficial effects are that: the invention provides a novel electrode design structure, which designs the shape of an electrode into a sound velocity curve distribution shape, and forms resonance with maximum intensity by controlling the moment when sound waves reach the edge, so that the Q value is improved, and the performance of a device is improved.
The foregoing detailed description of the invention has been presented for purposes of illustration and description, and it should be understood that the invention is not limited to the particular embodiments disclosed, but is intended to cover all modifications, equivalents, alternatives, and improvements within the spirit and principles of the invention.
Claims (5)
1. An improved Q FBAR resonator, the resonator comprising:
the piezoelectric thin film comprises a substrate, a Bragg reflection layer, two electrodes and a piezoelectric thin film;
the Bragg reflection layer is paved on the upper surface of the substrate;
the upper surface of the Bragg reflection layer is connected with one electrode;
a piezoelectric film layer is arranged between the electrode and the other electrode.
The electrode is in a gradual electrode edge shape consistent with the speed gradient of the sound wave.
2. The improved Q FBAR resonator according to claim 1, wherein the electrode has a shape of: triangle, pentagon, circle.
3. The improved Q FBAR resonator according to claim 1, characterized in that the resonator has a structure of the type comprising: air gap type, silicon back side etching type, and solid state assembly type.
4. The FBAR resonator with improved Q-value according to claim 1, wherein the piezoelectric thin film is a ZnO thin film.
5. The improved Q FBAR resonator as claimed in claim 1, wherein the electrode comprises: metal electrodes Mo, W, al.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310720317.1A CN116961617A (en) | 2023-06-19 | 2023-06-19 | FBAR resonator capable of improving Q value |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310720317.1A CN116961617A (en) | 2023-06-19 | 2023-06-19 | FBAR resonator capable of improving Q value |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN116961617A true CN116961617A (en) | 2023-10-27 |
Family
ID=88457315
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310720317.1A Pending CN116961617A (en) | 2023-06-19 | 2023-06-19 | FBAR resonator capable of improving Q value |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN116961617A (en) |
-
2023
- 2023-06-19 CN CN202310720317.1A patent/CN116961617A/en active Pending
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