CN112953436B - SAW-BAW hybrid resonator - Google Patents
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- 239000000758 substrate Substances 0.000 claims abstract description 33
- 230000008878 coupling Effects 0.000 claims abstract description 26
- 238000010168 coupling process Methods 0.000 claims abstract description 26
- 238000005859 coupling reaction Methods 0.000 claims abstract description 26
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 42
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 claims description 29
- 235000012239 silicon dioxide Nutrition 0.000 claims description 18
- 239000000377 silicon dioxide Substances 0.000 claims description 18
- 238000010897 surface acoustic wave method Methods 0.000 claims description 18
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 12
- 239000000463 material Substances 0.000 claims description 10
- 229910052681 coesite Inorganic materials 0.000 claims description 8
- 229910052906 cristobalite Inorganic materials 0.000 claims description 8
- 229910052682 stishovite Inorganic materials 0.000 claims description 8
- 229910052905 tridymite Inorganic materials 0.000 claims description 8
- 229910052594 sapphire Inorganic materials 0.000 claims description 5
- 239000010980 sapphire Substances 0.000 claims description 5
- 239000010453 quartz Substances 0.000 claims description 3
- 229910052706 scandium Inorganic materials 0.000 claims description 3
- SIXSYDAISGFNSX-UHFFFAOYSA-N scandium atom Chemical compound [Sc] SIXSYDAISGFNSX-UHFFFAOYSA-N 0.000 claims description 3
- 229910052710 silicon Inorganic materials 0.000 claims description 3
- 239000010703 silicon Substances 0.000 claims description 3
- 229910052751 metal Inorganic materials 0.000 claims description 2
- 239000002184 metal Substances 0.000 claims description 2
- 229910001092 metal group alloy Inorganic materials 0.000 claims description 2
- 229910052697 platinum Inorganic materials 0.000 claims description 2
- 150000002739 metals Chemical class 0.000 claims 1
- 238000004519 manufacturing process Methods 0.000 abstract description 10
- 230000004044 response Effects 0.000 abstract description 3
- 239000010408 film Substances 0.000 description 127
- 239000010409 thin film Substances 0.000 description 19
- 230000001902 propagating effect Effects 0.000 description 12
- 230000008859 change Effects 0.000 description 8
- DCSUBABJRXZOMT-IRLDBZIGSA-N cisapride Chemical compound C([C@@H]([C@@H](CC1)NC(=O)C=2C(=CC(N)=C(Cl)C=2)OC)OC)N1CCCOC1=CC=C(F)C=C1 DCSUBABJRXZOMT-IRLDBZIGSA-N 0.000 description 6
- 229960005132 cisapride Drugs 0.000 description 6
- DCSUBABJRXZOMT-UHFFFAOYSA-N cisapride Natural products C1CC(NC(=O)C=2C(=CC(N)=C(Cl)C=2)OC)C(OC)CN1CCCOC1=CC=C(F)C=C1 DCSUBABJRXZOMT-UHFFFAOYSA-N 0.000 description 6
- 230000007423 decrease Effects 0.000 description 6
- 238000010295 mobile communication Methods 0.000 description 6
- 230000009286 beneficial effect Effects 0.000 description 3
- 229910052814 silicon oxide Inorganic materials 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 238000004891 communication Methods 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 238000003780 insertion Methods 0.000 description 2
- 230000037431 insertion Effects 0.000 description 2
- 238000003475 lamination Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 238000005457 optimization Methods 0.000 description 2
- WSMQKESQZFQMFW-UHFFFAOYSA-N 5-methyl-pyrazole-3-carboxylic acid Chemical compound CC1=CC(C(O)=O)=NN1 WSMQKESQZFQMFW-UHFFFAOYSA-N 0.000 description 1
- PIGFYZPCRLYGLF-UHFFFAOYSA-N Aluminum nitride Chemical group [Al]#N PIGFYZPCRLYGLF-UHFFFAOYSA-N 0.000 description 1
- 229910013641 LiNbO 3 Inorganic materials 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
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
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/46—Filters
- H03H9/64—Filters using surface acoustic waves
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- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)
- Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
Abstract
The invention discloses a SAW-BAW hybrid resonator, which comprises a first electrode layer, a first piezoelectric film layer, a second electrode layer and a substrate layer which are sequentially arranged; the front projection of the first electrode layer and the front projection of the first piezoelectric film layer on the substrate layer are overlapped, and the front projection of the second piezoelectric film layer and the front projection of the second electrode layer on the substrate layer are overlapped; the first electrode layer and the first piezoelectric film layer are formed into a whole and are periodically and equally spaced on the second piezoelectric film layer; the second piezoelectric film layer has a lower piezoelectric coupling constant than the first piezoelectric film layer and a higher acoustic impedance than the first piezoelectric film layer. The SAW-BAW hybrid resonator of the invention can have excellent characteristics of high frequency, high K 2, high Q value and the like by utilizing a West Sha Wabo mode; not only can effectively inhibit clutter response caused by Rayleigh waves and bulk waves, but also has simple structure, reduces the manufacturing difficulty and the production cost of devices, and has great application prospect.
Description
Technical Field
The invention belongs to the technical field of piezoelectric micro-acoustic devices, relates to a SAW-BAW hybrid resonator (a surface acoustic wave and bulk acoustic wave micro-acoustic hybrid device), and particularly relates to a SAW-BAW hybrid resonator suitable for a mobile communication radio frequency front-end high-frequency broadband micro-acoustic filter.
Background
With the rapid development of mobile communication systems, piezoelectric micro-acoustic devices have been widely used in mobile communication devices as core elements of filters. In order for current intelligent terminal devices to operate in different countries, mobile communication standards (UMTS, HSPA, LTE, etc.) supporting more than 40 frequency bands are required. Especially, the advent of the fifth Generation mobile communication technology (5 th-Generation, 5G) has pushed the overall upgrade of the terminal radio frequency system, and based on the multiple increase of the number of base station antenna channels, the filter requirement is greatly increased for adding the communication function of the new frequency band. This puts more stringent requirements on filters for the radio frequency front section of mobile communications, in particular, acoustic wave resonators for filters should have higher operating frequencies and greater electromechanical coupling coefficients for high frequency, large bandwidth applications.
Currently, surface acoustic wave (SAW: surface Acoustic Wave) devices and bulk acoustic wave (BAW: bulk Acoustic Wave) devices are the dominant choices for mobile radio frequency front-end filters by virtue of their excellent frequency selectivity, high quality factor (Q value), low insertion loss, etc. The SAW device has simple preparation process and low cost, and the materials commonly used for the piezoelectric substrate are mainly lithium niobate (LiNbO 3), lithium tantalate (LiTaO 3) and silicon dioxide SiO 2, but due to the low sound velocity of the materials, the SAW filter is not suitable for working frequencies above 2.5GHz, in addition, the higher the frequency is, the smaller the interval between IDT electrodes is, and the electromigration is caused by too high current density (high power) at a small interval (high frequency). Compared with SAW devices, the BAW devices have the advantages that the sound waves are transmitted in the piezoelectric film body, are more suitable for high frequency, can theoretically meet the communication requirement within 20GHz, and have the size which is reduced along with the increase of the frequency. In addition, the BAW filter has the advantages of high Q value, small insertion loss, large out-of-band attenuation and the like. Thus, BAW devices are more advantageous in high frequency applications. But BAW devices are more costly to manufacture than SAW devices because of the 10 times the manufacturing process steps required. SAW/BAW devices have advantages, and developing a device that can have both advantages of SAW-BAW has great application prospects.
A SAW/BAW hybrid resonator based on a Mo/ScAlN/Mo/6H-SiC structure is disclosed in document "Dual-Mode Hybrid Quasi-SAW/BAW Resonators With High Effective Coupling Coefficient(2020IEEE Transactions on Ultrasonics,Ferroelectrics,and Frequency Control)", which has a large electromechanical coupling coefficient (K 2 -14.55%) and a high acoustic velocity (V-7500 m/s or more), which makes such a SAW/BAW hybrid resonator very potential in broadband and high frequency applications. But the high sonic substrate 6H-SiC used in addition is costly to produce and difficult to manufacture in large dimensions due to the Q-value of the device, thus limiting their mass production in industrial applications. Meanwhile, the SAW/BAW hybrid device has the excellent characteristics of high frequency and high electromechanical coupling coefficient, and has good application prospect.
Therefore, it is of great practical significance to develop a SAW-BAW hybrid resonator that is low cost and excellent in performance (Q value).
Disclosure of Invention
The invention aims to overcome the defect of overhigh cost of the conventional SAW/BAW hybrid resonator and provide a SAW-BAW hybrid resonator with low cost and excellent performance (high frequency, high sound velocity and high Q value).
In order to achieve the above purpose, the present invention provides the following technical solutions:
A SAW-BAW hybrid resonator comprises a first electrode layer, a first piezoelectric film layer, a second electrode layer and a substrate layer which are sequentially arranged;
The front projection of the first electrode layer and the front projection of the first piezoelectric film layer on the substrate layer are overlapped, and the front projection of the second piezoelectric film layer and the front projection of the second electrode layer on the substrate layer are overlapped;
the first electrode layer and the first piezoelectric film layer are formed into a whole and are periodically and equally spaced on the second piezoelectric film layer;
The second piezoelectric film layer has a lower piezoelectric coupling constant than the first piezoelectric film layer and a higher acoustic impedance than the first piezoelectric film layer.
The first electrode layer, the first piezoelectric thin film layer (the first electrode layer and the first piezoelectric thin film layer are columnar structures in the second piezoelectric thin film layer as a whole), the second piezoelectric thin film layer and the second electrode layer constitute a bulk acoustic wave (Bulk acoustic wave, BAW) resonator, and the bulk acoustic wave resonator and the substrate layer constitute a surface acoustic wave (Surface acoustic wave, SAW) resonator.
The first electrode layer and the first piezoelectric film layer are used to replace interdigital transducers in a surface acoustic wave resonator in the prior art, because the wavelength of the bulk acoustic wave excited in a special periodically arranged columnar structure on the first piezoelectric film layer corresponds to the wavelength of the surface acoustic wave of the substrate layer under certain conditions, wherein the wavelength of the surface acoustic wave and the bulk acoustic wave of the same frequency can effectively convert the bulk acoustic wave into the surface acoustic wave on the surface of the substrate, and the formed SAW-BAW hybrid resonator can be regarded as a SAW device.
As a preferable technical scheme:
the SAW-BAW hybrid resonator is characterized in that the materials of the first electrode layer and the second electrode layer are the same or different, and the first electrode layer and the second electrode layer are Pt, au, mo, W, al, cu metal simple substances or metal alloys or any combination of the materials;
the orthographic projection of the first electrode layer on the substrate layer is located within the orthographic projection of the second electrode layer on the substrate layer.
A SAW-BAW hybrid resonator as described above, the normalized electrode thicknesses h e of the first and second electrode layers each satisfying: h e is less than or equal to 0.02λ and less than or equal to 0.2λ, where λ is the wavelength of the surface acoustic wave.
According to the SAW-BAW hybrid resonator, the first piezoelectric film layer is the scandium-doped aluminum nitride (ScAlN) film, the doped mole percentage of scandium in the scandium-doped aluminum nitride film is 10% -40%, good c-axis orientation and piezoelectric performance of the ScAlN film can be guaranteed, and as different doped mole percentages of the scandium-doped aluminum nitride piezoelectric film have different piezoelectric performances, the scandium-doped aluminum nitride film with different doped mole percentages can be optimized according to actual needs, and the electromechanical coupling coefficient is improved due to the fact that the piezoelectricity is increased;
The second piezoelectric film layer is an aluminum nitride (AlN) film and has the function of a high sound velocity resistance layer, so that the SAW excited on the structure has high sound velocity. The first piezoelectric film layer and the second piezoelectric film layer are made of different materials, so that the high sound velocity is ensured, and meanwhile, the piezoelectric layers (the first piezoelectric film layer and the second piezoelectric film layer) still have high electromechanical coupling coefficients.
A SAW-BAW hybrid resonator as described above, wherein the film normalized thickness d of the first piezoelectric film layer and the sum h of the normalized thicknesses of the first piezoelectric film layer and the second piezoelectric film layer satisfy the following relationship:
0≤d≤0.9λ；
0.1λ≤h≤0.9λ；
0≤ratio≤1，ratio＝d/h；
Where λ is the surface acoustic wave wavelength.
The target acoustic wave modes excited by the first piezoelectric film layer and the second piezoelectric film layer include Rayleigh waves and West Sha Wabo wave modes and higher-order wave modes.
A SAW-BAW hybrid resonator as described above, further comprising an acoustically reflective layer between the second electrode layer and the substrate layer;
the acoustic reflection layer includes a low acoustic impedance layer and a high acoustic impedance layer;
The acoustic velocity of the low acoustic impedance layer is less than the acoustic velocity of the high acoustic impedance layer, the low acoustic impedance layer being closer to the second electrode layer than the high acoustic impedance layer. The acoustic reflection layer mainly solves the technical problem of SAW energy leakage, and can improve the electromechanical coupling coefficient.
A SAW-BAW hybrid resonator as described above, the low acoustic impedance layer being a SiO 2 film, siON film, or Ta 2O5 film; the high acoustic impedance layer is an AlN film, a Sapphire film, a SiN film, a Mo film or a Pt film. The scope of the invention is not limited to this, but only to a few of the possible solutions, and a person skilled in the art can choose suitable materials according to the actual requirements.
A SAW-BAW hybrid resonator as described above, wherein the low acoustic impedance layer is a SiO 2 film, and the normalized thickness h SiO2 of the SiO 2 film satisfies the following relationship: 0.1λ is not more than h SiO2 is not more than λ, λ is the surface acoustic wave wavelength, and too thick or too thin of the SiO 2 film can cause K 2 to decrease.
A SAW-BAW hybrid resonator as described above, wherein the high acoustic impedance layer is an AlN film, and the normalized thickness h AlN of the AlN film satisfies the following relationship: and 0.1λ is less than or equal to h AlN and less than or equal to λ, wherein λ is the wavelength of the surface acoustic wave. Because the AlN layer has a slight tuning effect on SAW energy propagation, the thickness of the AlN film can be adjusted within a certain range according to practical requirements by a person skilled in the art, but the adjustment amplitude is not excessively large.
In the SAW-BAW hybrid resonator described above, the substrate layer is made of a substrate material such as silicon (Si), sapphire (Sapphire), and Quartz (Quartz). The invention only gives a feasible technical proposal, the protection scope of the invention is not limited to the proposal, and a person skilled in the art can select proper materials according to actual requirements
The beneficial effects are that:
(1) The SAW-BAW hybrid resonator has a simple structure, can effectively inhibit clutter response caused by Rayleigh waves and bulk waves through effective structural optimization design, and is very beneficial to the application of high-frequency and broadband filters;
(2) The SAW-BAW hybrid resonator can obtain high frequency, high K 2 and high Q value simultaneously by utilizing a West Sha Wabo mode, has excellent performance, avoids complex process steps of a BAW device, reduces the manufacturing difficulty and the production cost of the device, and has great application prospect.
Drawings
FIGS. 1 and 2 are schematic top and cross-sectional views, respectively, of a SAW-BAW hybrid resonator of example 1;
FIG. 3 is a schematic cross-sectional view of a SAW-BAW hybrid resonator of example 2;
FIG. 4 is a schematic cross-sectional view of a SAW-BAW hybrid resonator of example 3;
FIG. 5 is a graph of typical input admittance versus frequency for a SAW-BAW hybrid resonator of example 1 at a characteristic frequency;
FIG. 6 is a graph showing the variation of electromechanical coupling coefficient (K 2) of West Sha Wabo propagating at different piezoelectric film layer film thicknesses (first piezoelectric film layer+second piezoelectric film layer) of the SAW-BAW hybrid resonator of example 1 as a function of ratio of piezoelectric film layer film thicknesses (ratio);
fig. 7 is a graph showing a change in phase velocity (V) of a cisapra wave propagating at different thicknesses of the piezoelectric thin film layers (first piezoelectric thin film layer + second piezoelectric thin film layer) of the SAW-BAW hybrid resonator of example 1, with respect to the ratio (ratio) of the thicknesses of the piezoelectric thin film layers;
FIG. 8 is a graph showing the variation of the electromechanical coupling coefficient (K 2) of the West Sha Wabo propagating at different piezoelectric film layer film thicknesses (first piezoelectric film layer+second piezoelectric film layer) of the SAW-BAW hybrid resonators of example 1 and example 2, as a function of the ratio (ratio) of the piezoelectric film layer film thicknesses;
Fig. 9 is a graph showing a change in phase velocity (V) of a cisapra wave propagating at different thicknesses of the piezoelectric thin film layers (first piezoelectric thin film layer + second piezoelectric thin film layer) of the SAW-BAW hybrid resonator of example 1 and example 2, as a function of the ratio (ratio) of the thicknesses of the piezoelectric thin film layers;
FIG. 10 is a graph of the electromechanical coupling coefficient (K 2) of West Sha Wabo propagating on the SAW-BAW hybrid resonator of example 2 as a function of silicon dioxide film thickness;
FIG. 11 is a graph of phase velocity (V) of a Sishaw wave propagating on a SAW-BAW hybrid resonator of example 2 as a function of silicon dioxide film thickness;
FIG. 12 is a graph of the electromechanical coupling coefficient (K 2) of West Sha Wabo propagating on the SAW-BAW hybrid resonator of example 3 as a function of aluminum nitride film thickness;
FIG. 13 is a graph of phase velocity (V) of a Sishaw wave propagating on a SAW-BAW hybrid resonator of example 3 as a function of aluminum nitride film thickness;
The piezoelectric ceramic comprises a first electrode layer, a second electrode layer, a first piezoelectric film layer, a second piezoelectric film layer, a third piezoelectric film layer, a fourth electrode layer, a 5-acoustic reflection layer, a 51-low acoustic impedance layer, a 52-high acoustic impedance layer and a 6-substrate layer.
Detailed Description
The following detailed description of the invention will be further presented in conjunction with the appended drawings, and it will be apparent that the described embodiments are merely some, but not all, examples of the invention.
In the description of the present invention, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "top," "bottom," "inner," "outer," and the like indicate or are based on the orientation or positional relationship shown in the drawings, merely to facilitate description of the present invention and to simplify the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention.
Example 1
A SAW-BAW hybrid resonator, as shown in fig. 1 and 2, includes a first electrode layer 1, a first piezoelectric thin film layer 2, a second piezoelectric thin film layer 3, a second electrode layer 4, and a substrate layer 6, which are sequentially arranged;
The front projection of the first electrode layer 1 and the front projection of the first piezoelectric film layer 2 on the substrate layer 6 are overlapped, the front projection of the second piezoelectric film layer 3 and the front projection of the second electrode layer 4 on the substrate layer 6 are overlapped, the front projection of the first electrode layer 1 on the substrate layer 6 is positioned in the front projection of the second electrode layer 4 on the substrate layer 6, and the whole of the first electrode layer 1 and the first piezoelectric film layer 2 are arranged on the second piezoelectric film layer 3 periodically and at equal intervals;
The materials of the first electrode layer 1 and the second electrode layer 4 are Pt, the standardized electrode thickness h e of the first electrode layer and the second electrode layer is set to be 0.04 lambda, lambda is the acoustic surface wave wavelength, the substrate layer 6 is a silicon (Si) substrate layer, the first piezoelectric film layer 2 is a scandium-doped aluminum nitride film, the scandium-doped aluminum nitride film has a scandium doping mole percentage of 40%, the second piezoelectric film layer 3 is an aluminum nitride film, and the film standardized thickness d of the first piezoelectric film layer and the sum h of the standardized thicknesses of the first piezoelectric film layer and the second piezoelectric film layer satisfy the following relation:
0≤d≤0.9λ；
0.1λ≤h≤0.9λ；
0≤ratio≤1，ratio＝d/h。
Example 2
A SAW-BAW hybrid resonator, as shown in fig. 3, has substantially the same structure as in example 1, except that it further includes a low acoustic impedance layer 51 between the second electrode layer 4 and the substrate layer 6, the low acoustic impedance layer 51 being a SiO 2 film, the normalized thickness h SiO2 of the SiO 2 film satisfying the following relationship: h SiO2 is less than or equal to 0.1λ and less than or equal to λ.
Example 3
A SAW-BAW hybrid resonator, as shown in fig. 4, has substantially the same structure as that of embodiment 1, except that it further includes an acoustic reflection layer 5 between the second electrode layer 4 and the substrate layer 6;
The acoustic reflection layer 5 includes a low acoustic impedance layer 51 and a high acoustic impedance layer 52 (the acoustic velocity of the low acoustic impedance layer is smaller than that of the high acoustic impedance layer), the low acoustic impedance layer 51 being closer to the second electrode layer 4 than the high acoustic impedance layer 52;
The low acoustic impedance layer 51 is a SiO 2 film, and the normalized thickness h SiO2 of the SiO 2 film satisfies the following relationship: h SiO2 is less than or equal to 0.1λ and less than or equal to λ;
the high acoustic impedance layer 52 is an AlN film, and the normalized thickness h AlN of the AlN film satisfies the following relationship: h AlN is less than or equal to 0.1λ and less than or equal to λ.
Relevant test results for the above examples:
fig. 5 is a graph showing typical input admittance versus frequency for the SAW-BAW hybrid resonator of example 1 at a characteristic frequency, and it can be seen from fig. 5 that the SAW-BAW hybrid resonator excites various SAW modes including rayleigh waves and Gao Jiexi Sha Wabo, and furthermore, by optimizing the thickness of the piezoelectric laminated film (first piezoelectric film layer+second piezoelectric film layer), west Sha Wabo exhibits relatively excellent SAW characteristics. West Sha Wabo is here illustrated as the primary mode of operation.
Fig. 6 and 7 are graphs showing changes in electromechanical coupling coefficient (K 2) and phase velocity (V) of the SAW-BAW hybrid resonator of example 1 with respect to the ratio (ratio) of the thickness of the piezoelectric laminated film (first piezoelectric film layer + second piezoelectric film layer) propagating at different thicknesses of the piezoelectric laminated film (first piezoelectric film layer + second piezoelectric film layer), respectively, and as can be seen from fig. 6, the western Sha Wabo exhibits relatively excellent surface acoustic wave characteristics with a change in the thickness ratio of the piezoelectric laminated film (first piezoelectric film layer + second piezoelectric film layer) given the different thicknesses of the piezoelectric laminated film (first piezoelectric film layer + second piezoelectric film layer). Further, as is clear from fig. 7, when h is 0.3λ to 0.9λ, and ratio is 0.4 to 0.9, electromechanical coupling coefficient K 2 of west Sha Wabo is relatively high (> 5%), and when scandium-doped aluminum nitride film (first piezoelectric thin-film layer) is 0.5λ, K 2 reaches a maximum value of 10%. The phase velocity of the cisawatt wave decreases with an increase in the ratio of the thicknesses of the piezoelectric laminated films (first piezoelectric film layer + second piezoelectric film layer). Wherein the phase velocity of the cisapride wave is about 3200-5500 m/s.
The piezoelectric stack film (first piezoelectric film layer+second piezoelectric film layer) thickness h in examples 1 and 2 was set to 0.4λ, while the silica film (low acoustic impedance layer) thickness in example 2 was set to 0.3λ, and then tested, fig. 8 and 9 are graphs showing the change in electromechanical coupling coefficient (K 2) and phase velocity (V) of the west Sha Wabo propagating on the SAW-BAW hybrid resonator of examples 1 and 2, respectively, with the ratio (ratio) of the piezoelectric stack film thickness. As can be seen from fig. 8, the electromechanical coupling coefficient K 2 of the si Sha Wabo of the silicon oxide thin film added in the range of 0.5 to 0.9 was relatively high (> 15%) as compared with the case where the silicon oxide thin film was not added, and K 2 reached the maximum value of 27% when the ratio (ratio) of the thickness of the piezoelectric thin film was 0.8. As can be seen from fig. 9, the phase velocity of the cisapride wave decreases with an increase in the ratio of the thickness of the piezoelectric stack film. Wherein the phase velocity of the cisapride wave is about 4500-5600 m/s.
The piezoelectric stack film (first piezoelectric film layer+second piezoelectric film layer) thickness h in example 2 was set to 0.4λ, the ratio (ratio) of the piezoelectric stack film thicknesses was 0.6, and then tests were performed, and fig. 10 and 11 are graphs showing the change in electromechanical coupling coefficient (K 2) and phase velocity (V) of west Sha Wabo propagating on the SAW-BAW resonator of example 2, respectively, with the thickness of the silicon oxide film. As can be seen from fig. 10, as the silicon dioxide film thickness becomes thicker, the electromechanical coupling coefficient K 2 of Sha Wabo shows a change in which it increases and decreases. As is clear from fig. 10, the electromechanical coupling coefficient K 2 of Sha Wabo is relatively high (> 15%) in the range of 0.1λ to 0.5λ of the silicon dioxide film thickness, and K 2 reaches the maximum value of 24% at 0.2λ of the silicon dioxide film thickness. As can be seen from fig. 11, the phase velocity of the cisapride wave decreases with an increase in the ratio of the thickness of the piezoelectric stack film. Wherein the phase velocity of the cisapride wave is about 4000 to 5500m/s. The propagation speed of SAW is slightly reduced due to the addition of the silicon dioxide thin film layer.
The piezoelectric laminated film (first piezoelectric film layer+second piezoelectric film layer) thickness h in example 3 was set to 0.4λ, the ratio (ratio) of the piezoelectric laminated film thicknesses was 0.6, the silica film (low acoustic impedance layer) thickness was 0.2λ, and then tested, fig. 12 and 13 are graphs showing the change in electromechanical coupling coefficient (K 2) and phase velocity (V) of the west Sha Wabo propagating on the SAW-BAW resonator of example 3, respectively, with the silica film thickness. As can be seen from fig. 12, as the thickness of the aluminum nitride film (high acoustic impedance layer) increases, the electromechanical coupling coefficient K 2 of Sha Wabo exhibits a change that decreases first and then increases. As can be seen from fig. 12, when the thickness of the aluminum nitride film is varied in the range of 0.1λ to 0.7λ, the electromechanical coupling coefficient K 2 of the zebra-Sha Wabo is significantly varied, and when the thickness of the aluminum nitride film is 0.7λ or more, K 2 is substantially maintained, and the SAW energy propagation is slightly tuned. As is clear from fig. 13, when the aluminum nitride film thickness is 0.7λ or more, the phase velocity of the shawa wave gradually increases with the aluminum nitride film thickness. Wherein the phase velocity of the cisapride wave is maintained at about 5000 m/s.
Through the test, the SAW-BAW hybrid resonator can realize the frequency band coverage of the hybrid resonator with the working frequency as high as about 1GHz by adjusting the related parameters when the wavelength is set to be 5 mu m, and the electromechanical coupling coefficient can be very high under the condition of ensuring high phase velocity. In addition, when the acoustic surface wave mode is selected and the period of the electrode is adjusted, the thickness of the piezoelectric lamination film can be adjusted at the same time so as to obtain a proper local thickness ratio of the piezoelectric lamination, so that the coverage of a frequency band up to more than 5GHz can be realized within a wide frequency range, and the electromechanical coupling coefficient of the acoustic wave resonator is ensured to be very high and has higher phase velocity.
Proved by verification, the SAW-BAW hybrid resonator has a simple structure, and can effectively inhibit clutter response caused by Rayleigh waves and bulk waves through effective structural optimization design, thereby being very beneficial to the application of high-frequency and broadband filters; the high-frequency high-K 2 high-Q-value high-voltage power supply device can obtain high-frequency high-K 2 high-Q-value simultaneously by utilizing a west Sha Wabo mode, is excellent in performance, avoids complex process steps of a BAW device, reduces manufacturing difficulty and production cost of the device, and has a great application prospect.
While particular embodiments of the present invention have been described above, it will be understood by those skilled in the art that these are by way of example only and that various changes or modifications may be made to these embodiments without departing from the principles and spirit of the invention.
Claims (8)
1. The SAW-BAW hybrid resonator is characterized by comprising a first electrode layer, a first piezoelectric film layer, a second electrode layer and a substrate layer which are sequentially arranged;
The front projection of the first electrode layer and the front projection of the first piezoelectric film layer on the substrate layer are overlapped, and the front projection of the second piezoelectric film layer and the front projection of the second electrode layer on the substrate layer are overlapped;
the first electrode layer and the first piezoelectric film layer are formed into a whole and are periodically and equally spaced on the second piezoelectric film layer;
The piezoelectric coupling constant of the second piezoelectric film layer is lower than that of the first piezoelectric film layer and the acoustic impedance of the second piezoelectric film layer is higher than that of the first piezoelectric film layer;
the first piezoelectric film layer is a scandium-doped aluminum nitride film, and the doped mole percentage of scandium in the scandium-doped aluminum nitride film is 10% -40%;
The second piezoelectric film layer is an aluminum nitride film;
the film standardized thickness d of the first piezoelectric film layer and the sum h of the standardized thicknesses of the first piezoelectric film layer and the second piezoelectric film layer satisfy the following relationship:
0≤d≤0.9λ；0.1λ≤h≤0.9λ；
0≤ratio≤1，ratio＝d/h；
Where λ is the surface acoustic wave wavelength.
2. A SAW-BAW hybrid resonator as claimed in claim 1, wherein the first and second electrode layers are of the same or different materials, being Pt, au, mo, W, al, cu elemental metals or metal alloys, or any combination thereof;
the orthographic projection of the first electrode layer on the substrate layer is located within the orthographic projection of the second electrode layer on the substrate layer.
3. A SAW-BAW hybrid resonator as claimed in claim 2, wherein the normalized electrode thicknesses h e of the first and second electrode layers each satisfy: h e is less than or equal to 0.02λ and less than or equal to 0.2λ, where λ is the wavelength of the surface acoustic wave.
4. A SAW-BAW hybrid resonator as in claim 1, further comprising an acoustically reflective layer between the second electrode layer and the substrate layer;
the acoustic reflection layer includes a low acoustic impedance layer and a high acoustic impedance layer;
The acoustic velocity of the low acoustic impedance layer is less than the acoustic velocity of the high acoustic impedance layer, the low acoustic impedance layer being closer to the second electrode layer than the high acoustic impedance layer.
5. The SAW-BAW hybrid resonator of claim 4, wherein the low acoustic impedance layer is a SiO 2 film, siON film, or Ta 2O5 film; the high acoustic impedance layer is an AlN film, a Sapphire film, a SiN film, a Mo film or a Pt film.
6. The SAW-BAW hybrid resonator of claim 5 wherein the low acoustic impedance layer is a SiO 2 film and the normalized thickness h SiO2 of the SiO 2 film satisfies the relationship: and 0.1λ is less than or equal to h SiO2 and less than or equal to λ, wherein λ is the wavelength of the surface acoustic wave.
7. The SAW-BAW hybrid resonator of claim 4 wherein the high acoustic impedance layer is an AlN film having a normalized thickness h AlN satisfying the relationship: and 0.1λ is less than or equal to h AlN and less than or equal to λ, wherein λ is the wavelength of the surface acoustic wave.
8. A SAW-BAW hybrid resonator as in claim 1, wherein the substrate layer is silicon, sapphire or quartz.
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| WO2022266789A1 (en) * | 2021-06-21 | 2022-12-29 | 中国科学技术大学 | Acoustic resonator based on high-crystallinity doped piezoelectric film and manufacturing method therefor |
| CN113584443B (en) * | 2021-06-30 | 2023-03-21 | 武汉大学 | AlN/AlScN nano composite piezoelectric coating for high-temperature-resistant fastener and preparation method thereof |
| CN113411066A (en) * | 2021-06-30 | 2021-09-17 | 中国电子科技集团公司第二十六研究所 | double-SAW resonator structure with high-frequency double-acoustic-wave mode and double-SAW filter |
| CN114884483B (en) * | 2022-05-09 | 2024-01-30 | 上海芯波电子科技有限公司 | Mixed laminated filter chip of SAW and BAW and manufacturing process thereof |
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