CN113411065A - Bulk acoustic wave resonator with Bragg reflection grating structure - Google Patents
Bulk acoustic wave resonator with Bragg reflection grating structure Download PDFInfo
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- CN113411065A CN113411065A CN202110681639.0A CN202110681639A CN113411065A CN 113411065 A CN113411065 A CN 113411065A CN 202110681639 A CN202110681639 A CN 202110681639A CN 113411065 A CN113411065 A CN 113411065A
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- bragg reflection
- bragg
- wave resonator
- acoustic wave
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- 239000000463 material Substances 0.000 claims abstract description 24
- 239000000758 substrate Substances 0.000 claims abstract description 17
- 239000013078 crystal Substances 0.000 claims abstract description 8
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims description 6
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 6
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 claims description 6
- 229910052782 aluminium Inorganic materials 0.000 claims description 6
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 6
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 claims description 6
- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 claims description 6
- 229910052750 molybdenum Inorganic materials 0.000 claims description 6
- 239000011733 molybdenum Substances 0.000 claims description 6
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 6
- 229910052594 sapphire Inorganic materials 0.000 claims description 6
- 239000010980 sapphire Substances 0.000 claims description 6
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 claims description 6
- 229910052721 tungsten Inorganic materials 0.000 claims description 6
- 239000010937 tungsten Substances 0.000 claims description 6
- 229910001080 W alloy Inorganic materials 0.000 claims description 5
- 229910052451 lead zirconate titanate Inorganic materials 0.000 claims description 5
- MAKDTFFYCIMFQP-UHFFFAOYSA-N titanium tungsten Chemical compound [Ti].[W] MAKDTFFYCIMFQP-UHFFFAOYSA-N 0.000 claims description 5
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims description 3
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 3
- 229910052454 barium strontium titanate Inorganic materials 0.000 claims description 3
- 229910003460 diamond Inorganic materials 0.000 claims description 3
- 239000010432 diamond Substances 0.000 claims description 3
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims description 3
- 229910052737 gold Inorganic materials 0.000 claims description 3
- 239000010931 gold Substances 0.000 claims description 3
- HFGPZNIAWCZYJU-UHFFFAOYSA-N lead zirconate titanate Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Ti+4].[Zr+4].[Pb+2] HFGPZNIAWCZYJU-UHFFFAOYSA-N 0.000 claims description 3
- 229910021421 monocrystalline silicon Inorganic materials 0.000 claims description 3
- 229910052697 platinum Inorganic materials 0.000 claims description 3
- 229910021420 polycrystalline silicon Inorganic materials 0.000 claims description 3
- 229920006149 polyester-amide block copolymer Polymers 0.000 claims description 3
- 229910021426 porous silicon Inorganic materials 0.000 claims description 3
- 235000012239 silicon dioxide Nutrition 0.000 claims description 3
- 239000000377 silicon dioxide Substances 0.000 claims description 3
- 229910052709 silver Inorganic materials 0.000 claims description 3
- 239000004332 silver Substances 0.000 claims description 3
- 229910052719 titanium Inorganic materials 0.000 claims description 3
- 239000010936 titanium Substances 0.000 claims description 3
- 239000011787 zinc oxide Substances 0.000 claims description 3
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims description 2
- 229910010271 silicon carbide Inorganic materials 0.000 claims description 2
- 238000002310 reflectometry Methods 0.000 abstract description 2
- 239000007787 solid Substances 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000004038 photonic crystal Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
- 230000003071 parasitic effect Effects 0.000 description 1
- 230000024241 parasitism Effects 0.000 description 1
Images
Classifications
-
- 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
- H03H9/02015—Characteristics of piezoelectric layers, e.g. cutting angles
-
- 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
- H03H9/02062—Details relating to the vibration mode
-
- 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
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- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)
Abstract
The invention discloses a bulk acoustic wave resonator with a Bragg reflection grating structure, which comprises a substrate, a Bragg reflection layer and a piezoelectric sandwich structure, wherein the Bragg reflection layer is arranged on the substrate; the piezoelectric sandwich structure sequentially comprises an upper electrode, a piezoelectric layer and a lower electrode from top to bottom; the Bragg reflection layer is arranged on the substrate, and the piezoelectric sandwich structure is arranged on the Bragg reflection structure; the Bragg acoustic reflection layer is formed by alternately stacking a low acoustic impedance layer and a high acoustic impedance layer, a scatterer is embedded in each layer of the Bragg reflection layer to form a phonon crystal, and the scatterer embedded in the Bragg reflection layer and the Bragg reflection layer jointly form an acoustic reflection layer at the bottom of the device; the scatterer and the high acoustic impedance layer in the low acoustic impedance layer are both made of high acoustic impedance materials, and the scatterer and the low acoustic impedance layer in the high acoustic impedance layer are both made of low acoustic impedance materials. The invention utilizes the high reflectivity characteristic of the phononic crystal to longitudinal waves and shear waves in the forbidden band range, greatly reduces the energy leaked from the Bragg to the substrate of the device and improves the Q value of the device.
Description
Technical Field
The invention relates to the technical field of radio frequency filters, in particular to a bulk acoustic wave resonator with a Bragg reflection grating structure.
Background
With the rapid commercialization of the fifth generation communication technology internationally, the conventional rf filter no longer satisfies the requirement for high frequency communication. Film Bulk Acoustic Resonators (FBARs) have become one of the mainstream filters of rf front-end devices in 5G communication systems due to their advantages of high Q value, large bandwidth, small size, etc. The solid assembled bulk acoustic wave resonator (SMR-BAW) does not need to prepare a cavity on a substrate, but adopts a Bragg structure formed by alternately forming films of two different materials to reflect acoustic waves back to a piezoelectric stack, so that the solid assembled bulk acoustic wave resonator has higher mechanical strength, higher device yield and longer device service life.
The Bragg sound wave reflection structure is formed by alternately combining high sound impedance films and low sound impedance films, when the thickness of each layer of film meets the Bragg reflection condition, the reflection of sound wave energy near the resonant frequency can be realized, and the reflection efficiency is close to that of air. However, some energy will still leak from the bragg structure into the substrate, and this energy will be reflected back into the piezoelectric stack through the substrate and cause parasitic resonance, resulting in a lower Q value of the SMR than that of a bulk acoustic resonator with a cavity.
Disclosure of Invention
The invention aims to overcome the defects of the existing solid assembly type bulk acoustic wave resonator technology, and provides a novel bulk acoustic wave resonator with a Bragg reflection grating structure.
The technical scheme adopted by the invention is as follows:
the invention comprises a substrate, a Bragg reflection layer and a piezoelectric sandwich structure; the piezoelectric sandwich structure sequentially comprises an upper electrode, a piezoelectric layer and a lower electrode from top to bottom; the Bragg reflection layer is arranged on the substrate, and the piezoelectric sandwich structure is arranged on the Bragg reflection structure; each of the bragg reflector layers has a scatterer embedded therein to form a phononic crystal.
Preferably, the substrate is made of monocrystalline silicon, silicon carbide, polycrystalline silicon, sapphire, lithium niobate, diamond or sapphire.
Preferably, the material of the piezoelectric layer is aluminum nitride, lithium niobate, lead zirconate titanate, barium strontium titanate, zinc oxide or PZT.
Preferably, the materials of the upper electrode and the lower electrode are aluminum, molybdenum, gold, tungsten, titanium, silver, platinum or titanium-tungsten alloy.
Preferably, the Bragg acoustic reflection layer is formed by alternately stacking low acoustic impedance layers and high acoustic impedance layers, and the total number of layers is 3-9; the thickness of each layer of the Bragg reflection layer is one quarter or three quarters of the wavelength of an acoustic wave signal excited by the bulk acoustic wave resonator at the parallel resonance in the layer material; and the acoustic impedance ratio range of the adjacent low-sound impedance layer and the high-sound impedance layer in the Bragg reflection layer is 2-4.
Preferably, the scatterer embedded in the bragg reflection layer and the bragg reflection layer together form a device bottom acoustic reflection layer.
More preferably, the scatterer and the high-sound impedance layer in the low-sound impedance layer are both made of high-sound impedance materials, and the acoustic impedance ratio of the low-sound impedance layer to the scatterer is 0.1-0.9.
More preferably, the scatterer and the low-sound impedance layer in the high-sound impedance layer are both made of low-sound impedance materials, and the acoustic impedance ratio of the high-sound impedance layer to the scatterer is 2-8.
More preferably, the scatterers in the low acoustic impedance layer and the high acoustic impedance layer each have a diameter of 50nm to 1000 nm.
More preferably, the low acoustic impedance material is aluminum, silicon dioxide, porous silicon or polyester amide, and the high acoustic impedance material is molybdenum, tungsten, titanium-tungsten alloy or aluminum nitride.
The invention has the following beneficial effects:
the conventional Bragg structure can only effectively reflect longitudinal waves, the phononic crystal is formed by embedding scattering bodies with different acoustic impedances into the Bragg reflection layer, and the phononic crystal has higher reflection coefficients for the longitudinal waves and the shear waves by utilizing the characteristics of low transmission and high reflection coefficient of the phononic crystal to sound waves in a forbidden band in a larger range, so that the energy is effectively inhibited in the piezoelectric oscillation stack, the Q value of a device is improved, and out-of-band parasitism is inhibited.
Drawings
Fig. 1 is a schematic structural diagram of a bulk acoustic wave resonator having a bragg reflector structure according to the present invention;
FIG. 2 is a schematic diagram of a Bragg reflection layer structure embedded in a scatterer according to the present invention;
figure 3 is a graph comparing the impedance magnitude of the bulk acoustic wave resonator of the present invention and a conventional SMR device.
Detailed Description
For a better description of the invention, reference will now be made to the following description taken in conjunction with the accompanying drawings.
As shown in fig. 1, a bulk acoustic wave resonator having a bragg reflection grating structure includes a substrate 1, a bragg reflection layer 2, a lower electrode 3, a piezoelectric layer 4, and an upper electrode 5; the bragg reflection layer 2 is formed by alternately stacking low acoustic impedance layers 6 and high acoustic impedance layers 7. The Bragg reflection layer 2 is positioned on the substrate 1, and an active sandwich structure consisting of a lower electrode 3, a piezoelectric layer 4 and an upper electrode 5 which are sequentially arranged from bottom to top is positioned on the Bragg reflection layer 2; as shown in fig. 2, each of the bragg reflection layers 2 is embedded in a scatterer to form a phononic crystal, the scatterer in the high acoustic impedance layer 7 is a low acoustic impedance material 9, and the scatterer in the low acoustic impedance layer 6 is a high acoustic impedance material 8.
The cross-section of the diffuser includes, but is not limited to, circular, rectangular; the substrate 1 is made of materials including but not limited to monocrystalline silicon, polycrystalline silicon, sapphire, lithium niobate, diamond and sapphire; materials selected for the low acoustic impedance layer 6 and the low acoustic impedance material 9 include, but are not limited to, aluminum, silicon dioxide, porous silicon, polyesteramide; the materials selected for the high acoustic impedance layer 7 and the high acoustic impedance material 8 include, but are not limited to, molybdenum, tungsten, titanium-tungsten alloy, and aluminum nitride. The upper electrode 5 and the lower electrode 3 are made of materials including, but not limited to, aluminum, molybdenum, gold, tungsten, titanium, silver, and platinum; the piezoelectric layer 4 is made of materials including, but not limited to, aluminum nitride, lithium niobate, lead zirconate titanate, barium strontium titanate, and zinc oxide.
As shown in fig. 3, the impedance curve of the bulk acoustic wave resonator of the present invention is smoother over a wide frequency band as compared to the conventional SMR device. The Q value of the parallel resonance point of the traditional SMR device is lower because longitudinal wave and shear wave energy are partially leaked into the substrate at the parallel resonance point, but the photonic crystal is embedded in the Bragg structure, and the high reflectivity characteristic of the photonic crystal to the longitudinal wave and the shear wave in a forbidden band is utilized, so that the energy loss of the device is reduced, and the Q value of the device is improved.
Claims (10)
1. The utility model provides a bulk acoustic wave resonator with Bragg reflection grating structure, includes substrate, Bragg reflection stratum and piezoelectricity sandwich structure, its characterized in that: the piezoelectric sandwich structure sequentially comprises an upper electrode, a piezoelectric layer and a lower electrode from top to bottom; the Bragg reflection layer is arranged on the substrate, and the piezoelectric sandwich structure is arranged on the Bragg reflection structure; each of the bragg reflector layers has a scatterer embedded therein to form a phononic crystal.
2. The bulk acoustic wave resonator having the bragg reflection grating structure according to claim 1, wherein: the substrate is made of monocrystalline silicon, silicon carbide, polycrystalline silicon, sapphire, lithium niobate, diamond or sapphire.
3. The bulk acoustic wave resonator having the bragg reflection grating structure according to claim 1, wherein: the piezoelectric layer is made of aluminum nitride, lithium niobate, lead zirconate titanate, barium strontium titanate, zinc oxide or PZT.
4. The bulk acoustic wave resonator having the bragg reflection grating structure according to claim 1, wherein: the upper electrode and the lower electrode are made of aluminum, molybdenum, gold, tungsten, titanium, silver, platinum or titanium-tungsten alloy.
5. The bulk acoustic wave resonator having the bragg reflection grating structure according to claim 1, wherein: the Bragg acoustic reflection layer is formed by alternately stacking low acoustic impedance layers and high acoustic impedance layers, and the total number of layers is 3-9; the thickness of each layer of the Bragg reflection layer is one quarter or three quarters of the wavelength of an acoustic wave signal excited by the bulk acoustic wave resonator at the parallel resonance in the layer material; and the acoustic impedance ratio range of the adjacent low-sound impedance layer and the high-sound impedance layer in the Bragg reflection layer is 2-4.
6. The bulk acoustic wave resonator having the bragg reflection grating structure according to claim 1, wherein: and the scatterer embedded in the Bragg reflection layer and the Bragg reflection layer jointly form an acoustic reflection layer at the bottom of the device.
7. The bulk acoustic wave resonator having the bragg reflection grating structure according to claim 5, wherein: the scatterer and the high-sound impedance layer in the low-sound impedance layer are made of high-sound impedance materials, and the acoustic impedance ratio of the low-sound impedance layer to the scatterer is 0.1-0.9.
8. The bulk acoustic wave resonator having the bragg reflection grating structure according to claim 7, wherein: the scatterer and the low-sound impedance layer in the high-sound impedance layer are both made of low-sound impedance materials, and the acoustic impedance ratio of the high-sound impedance layer to the scatterer is 2-8.
9. A bulk acoustic wave resonator having a bragg reflector grating structure according to claim 5, 7 or 8, wherein: the diameters of the scatterers in the low acoustic impedance layer and the high acoustic impedance layer are both 50 nm-1000 nm.
10. The bulk acoustic wave resonator having the bragg reflector grating structure according to claim 8, wherein: the low-acoustic-impedance material is aluminum, silicon dioxide, porous silicon or polyester amide; the high acoustic impedance material is molybdenum, tungsten, titanium-tungsten alloy or aluminum nitride.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN202110681639.0A CN113411065A (en) | 2021-06-18 | 2021-06-18 | Bulk acoustic wave resonator with Bragg reflection grating structure |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110681639.0A CN113411065A (en) | 2021-06-18 | 2021-06-18 | Bulk acoustic wave resonator with Bragg reflection grating structure |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117118388A (en) * | 2023-08-21 | 2023-11-24 | 天通瑞宏科技有限公司 | Multilayer composite wafer and thin film elastic wave device |
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2021
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| US8525619B1 (en) * | 2010-05-28 | 2013-09-03 | Sandia Corporation | Lateral acoustic wave resonator comprising a suspended membrane of low damping resonator material |
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| CN117118388A (en) * | 2023-08-21 | 2023-11-24 | 天通瑞宏科技有限公司 | Multilayer composite wafer and thin film elastic wave device |
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Application publication date: 20210917 |