CN112600531A - Narrow-band filter with high-frequency near-zero frequency temperature coefficient and manufacturing method - Google Patents
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- 229910045601 alloy Inorganic materials 0.000 claims description 8
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- 229910052782 aluminium Inorganic materials 0.000 claims description 6
- 229910052802 copper Inorganic materials 0.000 claims description 6
- 229910052737 gold Inorganic materials 0.000 claims description 6
- 229910052750 molybdenum Inorganic materials 0.000 claims description 6
- 229910052759 nickel Inorganic materials 0.000 claims description 6
- 229910052697 platinum Inorganic materials 0.000 claims description 6
- 229910052719 titanium Inorganic materials 0.000 claims description 6
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- 238000007747 plating Methods 0.000 claims description 3
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- GYHNNYVSQQEPJS-UHFFFAOYSA-N Gallium Chemical compound [Ga] GYHNNYVSQQEPJS-UHFFFAOYSA-N 0.000 description 2
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 229910052733 gallium Inorganic materials 0.000 description 2
- 229910052746 lanthanum Inorganic materials 0.000 description 2
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
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- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 description 1
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- H—ELECTRICITY
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- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/46—Filters
- H03H9/54—Filters comprising resonators of piezoelectric or electrostrictive material
- H03H9/56—Monolithic crystal filters
- H03H9/564—Monolithic crystal filters implemented with thin-film techniques
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- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
- H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
- H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
- H03H3/04—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks for obtaining desired frequency or temperature coefficient
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
- H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
- H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
- H03H3/04—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks for obtaining desired frequency or temperature coefficient
- H03H2003/0407—Temperature coefficient
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Abstract
The invention relates to a narrow-band filter with a high-frequency near-zero frequency temperature coefficient and a manufacturing method thereof. The narrow band filter includes: a substrate layer of a high acoustic velocity material; an LGS low acoustic velocity material layer having an Euler angle of (90 DEG, 40 DEG) and a thickness of m lambda formed over a high acoustic velocity material substrate layer; a single crystal AlN high sound velocity material piezoelectric layer having a c-axis orientation and a thickness of 0.1 lambda formed on the LGS low sound velocity material layer, the single crystal AlN high sound velocity material piezoelectric layer having a c-axis orientation; and an IDT electrode provided on the piezoelectric layer of the single crystal AlN high acoustic velocity material having a c-axis orientation, wherein λ is an acoustic wavelength excited by the electrode. The invention can realize a resonator with zero TCF value or near zero TCF value, high Q value, low electromechanical coupling coefficient and no stray.
Description
Technical Field
The invention relates to an acoustic wave resonator/filter, in particular to a narrow-band filter with high frequency and near-zero frequency temperature coefficient in the radio frequency front end of a mobile phone and a manufacturing method thereof.
Background
With the development of wireless communication applications, people have higher and higher requirements on data transmission speed. Corresponding to the high utilization of spectrum resources and the complexity of the communication protocol. In order to support sufficient data transmission rates within a limited bandwidth, stringent requirements are placed on the various performances of the radio frequency system.
In the rf front-end module, the filter plays a crucial role. It can filter out-of-band interference and noise to meet the signal-to-noise ratio requirements of radio frequency systems and communication protocols. In the 5G era, in order to realize high bandwidth, the number of paths of the carrier aggregation technology must be increased, which also means that the number of frequency bands that the mobile phone needs to support is continuously increased, and since each frequency band needs to have its own filter, the number of filters in the rf front-end module is increasing, and the design of the filter is becoming more challenging.
There are currently three major types of filters in the field, Surface Acoustic Wave (SAW), Bulk Acoustic Wave (BAW), and thin film bulk acoustic wave (FBAR) filters.
The SAW filter mainly utilizes the piezoelectric effect, and when a voltage is applied to the crystal, the crystal is mechanically deformed, so that electric energy is converted into mechanical energy. SAW is the mainstream of low frequency and medium frequency band, and is very suitable for use below 1.5GHz, and the upper limit of frequency is 2.5-3 GHz. Its technology has evolved from Normal-SAW, TC-SAW, and further to IHP-SAW, as well as future XBAR technologies.
Existing IHP-SAW technology uses a hybrid technology similar to the multilayer reflective gate structure of SAW device + SMR-BAW device. The mixed structure technology not only endows the SAW device with the characteristic of simple single-side processing technology, but also endows the SMR-BAW device with the characteristic of low energy leakage.
The IHP-SAW filter is a major development direction of the SAW filter in the present stage because it has excellent temperature compensation performance, low insertion loss, and can compare with or even surpass the BAW and FBAR filters.
The IHP-SAW filter has the following three advantages:
1. the IHP-SAW filter with high Q value adopts a multi-layer reflection gate structure of SMR-BAW to focus more surface acoustic wave energy on the surface of the substrate, thereby reducing the loss of acoustic waves in the transmission process and improving the Q value of the device. The high Q characteristic (Qmax-3000, traditional SAW Qmax-1000) makes it have high out-of-band rejection, steep passband edge roll-off, and high isolation.
2. The TCF of the IHP-SAW can reach less than or equal to-20 ppm/DEG C, the further optimized design can reach 0 ppm/DEG C, and the TCF of the TC-SAW taking the lithium niobate as the piezoelectric layer is from-20 to-25 ppm/DEG C.
3. And (4) good heat dissipation performance.
The SMR-BAW multilayer reflection gate structure of the IHP-SAW filter is realized by alternately stacking high acoustic impedance and low acoustic impedance. The low acoustic impedance material mostly adopts TCF material with positive temperature coefficient, such as silicon dioxide; the high acoustic impedance layer is usually made of a material with a low temperature coefficient, such as SiN, W, etc.
However, the existing IHP-SAW technology has the following problems:
in IHP-SAW, although the TCF value is less than or equal to-20 ppm/DEG C, a slight temperature drift phenomenon still exists, high-performance products such as a high-frequency narrow-band filter with a zero TCF value or a near-zero TCF value (the TCF value is less than or equal to-5 ppm/DEG C) are not common, and the prior art cannot realize a filter with a zero temperature drift coefficient.
Therefore, a narrow band filter with a near-zero frequency temperature coefficient is needed.
Disclosure of Invention
This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter; nor is it intended to be used as an aid in determining or limiting the scope of the claimed subject matter.
The inventor notes that the TCF value of the LGS material (lanthanum gallium silicate) shows different values from-20 ppm/DEG C to 70 ppm/DEG C along with different Euler angles, and the invention utilizes the characteristics to adjust the thickness of AlN and LGS and the Euler angles and realize zero TCF value or near-zero TCF value.
The invention provides a narrow-band filter with a near-zero frequency temperature coefficient, which comprises: a substrate layer of a high acoustic velocity material; an LGS low sound velocity material layer formed on the high sound velocity material substrate layer, wherein the Euler angle of the LGS low sound velocity material layer is (90 degrees, 90 degrees and 40 degrees), the thickness is m lambda, and m is more than or equal to 1.4 and less than or equal to 1.6; a single crystal AlN high acoustic velocity material piezoelectric layer having a thickness of 0.1 lambda with c-axis orientation formed on the LGS low acoustic velocity material layer; and an electrode provided on the piezoelectric layer of the single crystal AlN high acoustic velocity material having a c-axis orientation, wherein λ is an acoustic wavelength excited by the electrode.
The narrow band filter may further include more high-sound-velocity-material substrate layers and LGS low-sound-velocity-material layers alternately stacked, and a single-crystal AlN high-sound-velocity-material piezoelectric layer having a c-axis orientation is formed on the uppermost LGS low-sound-velocity-material layer. The number of the high sound velocity material substrate layer and the number of the LGS low sound velocity material layer are n, and n is an integer of 2-9.
The high sound velocity material of the high sound velocity material substrate layer is at least one selected from Si, SiN, SiON, 3C-SiC, W, 4H-SiC or 6H-SiC, the thickness is 5 lambda-10 lambda, and the LGS low sound velocity material layer is plated on the high sound velocity material substrate layer in a mode of adopting one of PECVD, CVD, MOCVD and MBE. The electrode is an IDT electrode and is composed of one of Ti, Al, Cu, Au, Pt, Mo and Ni, an alloy thereof, or a laminate thereof. The electrodes may be upper and lower double layer electrodes. The duty cycle of the electrodes is 0.4-0.6.
The invention further proposes a method for manufacturing a narrow band filter with a near-zero frequency temperature coefficient, comprising: providing a high-sound-velocity material substrate layer, wherein the thickness of the high-sound-velocity material substrate layer is 5-10 lambda; plating an LGS low-sound-velocity material layer on a high-sound-velocity material substrate layer in one of PECVD, CVD, MOCVD and MBE modes, wherein the Euler angle of the LGS low-sound-velocity material layer is (90 degrees, 90 degrees and 40 degrees), the thickness of the LGS low-sound-velocity material layer is m lambda, and m is more than or equal to 1.4 and less than or equal to 1.6; forming a single crystal AlN high-sound-velocity material piezoelectric layer with c-axis orientation on the LGS low-sound-velocity material layer, wherein the thickness of the single crystal AlN high-sound-velocity material piezoelectric layer with the c-axis orientation is 0.1 lambda; and forming an IDT electrode on the piezoelectric layer of the single crystal AlN high-sound-velocity material with the c-axis orientation, wherein the IDT electrode is composed of one of Ti, Al, Cu, Au, Pt, Mo and Ni, or an alloy thereof, or a laminated body thereof, and λ is the acoustic wave wavelength excited by the IDT electrode.
According to the invention, the piezoelectric layer adopts single crystal AlN with c-axis orientation, the low sound velocity layer adopts LGS with special tangential Euler angles of (90 degrees, 90 degrees and 40 degrees), and a high-frequency near-zero frequency temperature coefficient and stray-free resonator can be obtained.
In addition, the LGS layer with low sound velocity and the substrate layer with high sound velocity form a Bragg reflection layer, so that the Q value of the resonator can be improved.
Furthermore, the invention combines the monocrystal AlN and the LGS, so as to realize low electromechanical coupling coefficient.
These and other features and advantages will become apparent upon reading the following detailed description and upon reference to the accompanying drawings. It is to be understood that both the foregoing general description and the following detailed description are explanatory only and are not restrictive of aspects as claimed.
Drawings
The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which specific embodiments of the invention are shown. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the application. Also, like reference numerals are used to refer to like parts throughout the drawings. The drawings are only schematic and are not to be construed as limiting the actual dimensional proportions.
Fig. 1 is a structural model diagram of a resonator of a narrow band filter according to the present invention;
fig. 2 is a schematic diagram of the resonators of a narrow band filter according to the present invention;
FIG. 3 is a schematic diagram of a Bragg reflector of a narrow band filter according to the present invention;
FIG. 4 is a schematic structural diagram of a resonator with n Bragg reflection layers;
FIG. 5 is a graph showing the change of TCF value with Euler angle at room temperature of LGS;
FIG. 6 is a graph of TCF values for a resonator with an LGS Euler angle (90, 40) as a function of LGS thickness;
fig. 7 is an admittance diagram of a resonator with an LGS euler angle of (90 °,90 °,40 °) having a TCF of 0;
fig. 8 is a flow chart of a manufacturing process of the narrow band filter of the present invention.
Detailed Description
The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which specific embodiments of the invention are shown. Various advantages and benefits of the present invention will become apparent to those of ordinary skill in the art upon reading the following detailed description of the specific embodiments. It should be understood, however, that the present invention may be embodied in various forms and should not be limited to the embodiments set forth herein. The following embodiments are provided so that the invention may be more fully understood. Unless otherwise defined, technical or scientific terms used herein shall have the ordinary meaning as understood by those of skill in the art to which this application belongs.
A resonator according to one embodiment of the present invention is discussed below in conjunction with the structural model diagram of fig. 1 and the schematic diagram of fig. 2.
As can be seen from the figure, the resonator comprises a substrate layer 101, a low acoustic velocity layer 102, a piezoelectric layer 103 and an electrode 104.
The substrate layer 101 of the resonator of the present invention is made of a high acoustic velocity material having high acoustic impedance, and may be made of Si, SiN, SiON, 3C-SiC, W, 4H-SiC, or 6H-SiC, and has a thickness of 5 λ to 10 λ (λ is the wavelength of an acoustic wave excited by an electrode finger, and λ is 1 μm).
The piezoelectric layer 103 is made of single crystal AlN with c-axis orientation, is made of a high sound velocity material, has a sound velocity of 11000-12000 m/s, and can greatly improve the central frequency f of the device01/2(fp + fs), meeting the requirements of 5G communication. The piezoelectric layer thickness is 0.1 λ. TCF of single crystal AlN-19 ppm/° c.
An interdigital transducer (IDT) electrode 104 is provided on the piezoelectric layer, the IDT electrode is composed of a metal or alloy such as Ti, Al, Cu, Au, Pt, Mo, Ni, or a laminate of these metals or alloys, and has an electromechanical coupling coefficient k2＝(π2/8)(fp2-fs2)/fs2Wherein fs is the resonance frequency and fp is the antiresonance frequency. The duty cycle of the electrodes may be selected from 0.4-0.6.
A layer of the LGS low acoustic velocity layer 102 is interposed between the piezoelectric layer 103 and the high acoustic velocity substrate layer 101. LGS is low acoustic impedance material, and the sound velocity is 2350-2850m/s, and has piezoelectric property. The LGS has different frequency temperature coefficients TCF according to different tangential directions, and the TCF value of the device can be reduced by overlapping the LGS with a positive frequency temperature coefficient and the single crystal AlN with a negative frequency temperature coefficient. The Euler angle of the LGS is preferably (90, 40).
The thickness of the LGS layer is m lambda, wherein m is preferably more than or equal to 1.4 and less than or equal to 1.6, and the LGS layer can be formed by plating an LGS layer on a substrate layer of a high-sound-velocity material in a PECVD (plasma enhanced chemical vapor deposition), CVD (chemical vapor deposition), MOCVD (metal organic chemical vapor deposition), MBE (molecular beam epitaxy) mode and the like.
Coefficient of thermal expansion CTE of LGS 5.15 × 10-6K-1Coefficient of thermal expansion CTE of single crystal AlN 5.2X 10-6K-1The two coefficients of thermal expansion are matched.
Fig. 3 shows that the LGS layer having a low acoustic velocity and the substrate layer of a high acoustic velocity material together form a bragg reflection layer, which prevents an acoustic wave from leaking from the direction of the substrate layer, and can improve the Q value of the device.
Fig. 1 and 2 show only one substrate layer of a high acoustic velocity material and one LGS layer of a low acoustic velocity. However, this may be multi-layered. Fig. 4 is a schematic structural diagram of an IHP resonator with multiple (n-layers) bragg reflective layers, where n may be preferably 2-9 layers, and the substrate layer of high sound velocity material and the low sound velocity layer (LGS layer) are alternately stacked, and those skilled in the art can select the corresponding number of layers according to design requirements.
FIG. 5 is a graph showing the change of TCF value with Euler angle at normal temperature of LGS.
The TCF value of LGS varies with euler angle (90 °,90 °, Φ) in the X-cut direction at normal temperature (T ═ 25 ℃), and as can be seen from the graph, the TCF value of LGS varies with the crystal tangent, and as Φ increases, the TCF value of LGS varies from 68ppm/° c to-15 ppm/° c, and when Φ is 40, the TCF is 68ppm/° c, which is the maximum value of the positive frequency temperature coefficient; when Φ is 140, TCF is-15 ppm/° c, the TCF value does not vary linearly with the Φ value.
Fig. 6 is a graph showing the TCF value of the resonator at an LGS euler angle (90 °,90 °,40 °) as a function of the LGS thickness.
It can be seen from the figure that single-crystal AlN has a thickness of 0.1 λ, LGS has a thickness of m λ, λ being 1 μm, preferably 1.4 ≦ m ≦ 1.6, because when m > 4, many complex high-order modes are introduced due to the particularity of both LGS and single-crystal AlN materials. The Euler angle of LGS was (90 DEG, 40 DEG), and it was found that the TCF value of the resonator did not change linearly with the change in the LGS film thickness, and hLGSWhen 1.5 λ, the resonator TCF is 0, and when h isLGSTCF is less than or equal to-5 ppm/DEG C when the temperature is 1.4-1.6 lambda.
Fig. 7 is an admittance chart of a resonator having an LGS euler angle of (90 °,90 °,40 °) with TCF equal to 0.
Wherein h isLGS1.5 lambda, sound velocity V3481 m/s, fs 3.479GHz, fp 3.483GHz, f03.481GHz and relative bandwidth 2Xk2，k20.32%, relative bandwidth of 0.64%, relative bandwidth of narrow band less than 5%, relative bandwidth of wide band between 5% and 25%, relative bandwidth of ultra wide band greater than 25%. Q1015, has a high Q value and is free of spurs.
Fig. 8 is a method of the present invention for manufacturing a narrow band filter with a low frequency temperature coefficient, comprising the steps of:
in step 801, a substrate layer of high acoustic velocity material is provided.
The high acoustic velocity material with high acoustic impedance may be Si, SiN, SiON, 3C-SiC, W, 4H-SiC or 6H-SiC, with a substrate layer thickness of 5 λ -10 λ (λ is the wavelength of the acoustic wave excited by the electrode fingers, λ ═ 1 μm).
In step 802, an LGS low acoustic velocity material layer is plated on the high acoustic velocity material substrate layer by PECVD, CVD, MOCVD, MBE, or the like.
The Euler angle of the LGS low acoustic velocity material layer is (90 DEG, 40 DEG); the LGS layer has a thickness of m lambda, where m is preferably 1.4. ltoreq. m.ltoreq.1.6.
The substrate layer of the high sound velocity material and the LGS layer of the low sound velocity material formed in the previous step together form a Bragg reflection layer. The person skilled in the art can choose a multilayer bragg reflector layer (which may preferably be 2-9 layers) according to the design needs. When the number n of layers is two or more, the process returns to step 801 after the end step 802 to form another bragg reflector layer. The process is cycled until n bragg reflective layers are formed.
In step 803, a single crystal AlN high acoustic velocity material piezoelectric layer having a c-axis orientation is formed over the uppermost LGS low acoustic velocity material layer, the piezoelectric layer having a thickness of 0.1 λ.
In step 804, IDT electrodes are formed on the piezoelectric layer of single crystal AlN high acoustic velocity material. The IDT electrode is made of a metal or alloy such as Ti, Al, Cu, Au, Pt, Mo, and Ni, or a laminate of these metals or alloys. The duty cycle of the electrodes may be selected from 0.4-0.6.
The TCF value of the LGS material (lanthanum gallium silicate) shows different values from-20 ppm/DEG C to 70 ppm/DEG C according to the difference of the Euler angles, the thickness of the monocrystalline AlN with c-axis orientation and the thickness of the LGS layer with low sound velocity are adjusted according to the invention, and the Euler angles of the LGS are set to (90 DEG, 90 DEG and 40 DEG), so that the resonator with zero TCF value or near zero TCF value and no stray is realized.
In addition, the LGS low sound velocity characteristic is utilized to form a Bragg reflection layer together with a high sound velocity substrate layer, so that the Q value of the resonator can be improved.
Further, by combining two piezoelectric materials, namely single crystal AlN and LGS, a low electromechanical coupling coefficient can be realized.
The above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present disclosure, and the present disclosure should be construed as being covered by the claims and the specification.
Claims (10)
1. A near-zero frequency temperature coefficient narrowband filter comprising:
a substrate layer of a high acoustic velocity material;
an LGS low-acoustic-velocity material layer formed over the high-acoustic-velocity material substrate layer, the LGS low-acoustic-velocity material layer having an Euler angle of (90 °,90 °,40 °), a thickness of m λ, wherein m is 1.4. ltoreq. m.ltoreq.1.6;
a single crystal AlN high sound velocity material piezoelectric layer having a c-axis orientation formed on the LGS low sound velocity material layer, the thickness of the single crystal AlN high sound velocity material piezoelectric layer having a c-axis orientation being 0.1 lambda; and
an electrode provided on the piezoelectric layer of the single crystal AlN high sound velocity material having the c-axis orientation,
where λ is the wavelength of the acoustic wave excited by the electrode.
2. The narrow band filter of claim 1, further comprising a further plurality of alternating layers of said high acoustic velocity material substrate layer and said LGS low acoustic velocity material layer, said single crystal AlN high acoustic velocity material piezoelectric layer having a c-axis orientation formed over an uppermost LGS low acoustic velocity material layer.
3. The narrow band filter of claim 2, wherein the number of layers of the substrate layer of high acoustic velocity material and the LGS layer of low acoustic velocity material are each n, n being an integer from 2 to 9.
4. The narrow band filter of claim 1, wherein the high acoustic velocity material of the high acoustic velocity material substrate layer is selected from at least one of Si, SiN, SiON, 3C-SiC, W, 4H-SiC, or 6H-SiC, having a thickness of 5 λ -10 λ, and the LGS low acoustic velocity material layer is deposited on the high acoustic velocity material substrate layer by one of PECVD, CVD, MOCVD, MBE.
5. The narrow band filter according to claim 1, wherein the electrode is an IDT electrode composed of one of Ti, Al, Cu, Au, Pt, Mo and Ni, or an alloy thereof, or a laminate thereof.
6. The narrow band filter according to claim 5, wherein said electrodes are upper and lower double layer electrodes.
7. The narrowband filter of claim 5, wherein the duty cycle of the electrodes is 0.4-0.6.
8. A method for fabricating a near-zero frequency temperature coefficient narrow band filter, comprising:
providing a substrate layer of a high acoustic velocity material;
plating an LGS low-sound-velocity material layer on the high-sound-velocity material substrate layer, wherein the Euler angle of the LGS low-sound-velocity material layer is (90 degrees, 90 degrees and 40 degrees), the thickness of the LGS low-sound-velocity material layer is m lambda, and m is more than or equal to 1.4 and less than or equal to 1.6;
forming a c-axis oriented single crystal AlN high-sound-velocity material piezoelectric layer on the LGS low-sound-velocity material layer, wherein the thickness of the c-axis oriented single crystal AlN high-sound-velocity material piezoelectric layer is 0.1 lambda; and
forming IDT electrodes on the piezoelectric layer of the single crystal AlN high sound velocity material having the c-axis orientation,
wherein λ is an acoustic wave wavelength excited by the IDT electrode.
9. The method of claim 8, wherein the LGS low acoustic velocity material layer is deposited on the substrate layer of high acoustic velocity material in a thickness of 5 λ to 10 λ using one of PECVD, CVD, MOCVD, and MBE.
10. The method of claim 8, wherein the IDT electrode is composed of one of Ti, Al, Cu, Au, Pt, Mo and Ni, or an alloy thereof, or a laminate thereof.
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| CN (1) | CN112600531A (en) |
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