CN116686217A - Resonator, filter and electronic device - Google Patents
Resonator, filter and electronic device Download PDFInfo
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- CN116686217A CN116686217A CN202180089501.XA CN202180089501A CN116686217A CN 116686217 A CN116686217 A CN 116686217A CN 202180089501 A CN202180089501 A CN 202180089501A CN 116686217 A CN116686217 A CN 116686217A
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- 238000010897 surface acoustic wave method Methods 0.000 claims description 5
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- 238000010586 diagram Methods 0.000 description 16
- 238000000034 method Methods 0.000 description 14
- 238000006073 displacement reaction Methods 0.000 description 9
- 230000001629 suppression Effects 0.000 description 9
- 230000000694 effects Effects 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 238000004088 simulation Methods 0.000 description 4
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- WSMQKESQZFQMFW-UHFFFAOYSA-N 5-methyl-pyrazole-3-carboxylic acid Chemical compound CC1=CC(C(O)=O)=NN1 WSMQKESQZFQMFW-UHFFFAOYSA-N 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- 235000019687 Lamb Nutrition 0.000 description 2
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
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- 229910052744 lithium Inorganic materials 0.000 description 2
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- 239000010453 quartz Substances 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 230000026683 transduction Effects 0.000 description 2
- 238000010361 transduction Methods 0.000 description 2
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
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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
- H03H9/15—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
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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 application provides a resonator, a filter and electronic equipment, relates to the field of resonators, and can improve the quality factor of the resonator; the resonator comprises a piezoelectric substrate and an interdigital transducer arranged on the piezoelectric substrate; the parallel arrangement direction of the plurality of interdigital electrodes is a first direction; the piezoelectric substrate is provided with side grooves along a first direction on at least one side of the plurality of interdigital electrodes.
Description
The present application relates to the field of resonators, and in particular, to a resonator, a filter, and an electronic device.
The energy loss of the resonator directly determines the quality factor, and the smaller the energy loss of the resonator is, the higher the quality factor is, and the better the performance of the resonator is, so that improving the quality factor of the resonator is one of the main ways to improve the performance of the resonator at present.
Disclosure of Invention
The embodiment of the application provides a resonator, a filter and electronic equipment, which can improve the quality factor of the resonator.
The application provides a resonator, which comprises a piezoelectric substrate and an interdigital transducer arranged on the piezoelectric substrate; the interdigital transducer comprises a first bus bar, a second bus bar and a plurality of interdigital electrodes which are arranged in parallel; in the present application, a direction in which a plurality of interdigital electrodes are juxtaposed is defined as a first direction, and a direction perpendicular to the first direction is defined as a second direction; the first bus bar and the second bus bar are distributed on two sides of the plurality of interdigital electrodes along the second direction; the plurality of interdigital electrodes comprise first interdigital electrodes and second interdigital electrodes which are alternately arranged in sequence along a first direction; the first interdigital electrode is connected with the first bus bar, and the second interdigital electrode is connected with the second bus bar. In the working process of the resonator, the interdigital transducer can convert an input electrical signal into sound wave vibration through the first interdigital electrode by utilizing the inverse piezoelectric effect of piezoelectric materials in the piezoelectric substrate, and convert the sound wave vibration back into an electrical signal through the second interdigital electrode by utilizing the positive piezoelectric effect, so that the acousto-electric transduction is realized.
On the basis, in the resonator provided by the embodiment of the application, the groove is arranged on the piezoelectric substrate and is used for inhibiting the stray of the resonator; the resonator can generate acoustic impedances with larger difference at the positions of the grooves, and improves the reflection efficiency when the acoustic waves propagate to the positions of the grooves, so that the energy loss of the resonator in the acoustic wave propagation direction at the resonance frequency is reduced, and the quality factor of the resonator is further improved.
In some possible implementations, the grooves include side grooves; the piezoelectric substrate is provided with side grooves along a first direction and positioned on at least one side of the plurality of interdigital electrodes; under the condition, the resonator can generate acoustic impedances with larger difference at the side groove positions, and when the sound waves propagate to the side groove positions, reflection can be generated, namely, reflection efficiency of the sound waves is improved, so that energy loss of the resonator in the sound wave propagation direction under the resonance frequency is reduced, and the quality factor of the resonator is improved.
In some possible implementations, the piezoelectric substrate is provided with side grooves on both sides of the plurality of interdigital electrodes along the first direction; the energy in the acoustic wave propagation direction of the resonator is reflected through the side grooves on the two sides, and the energy in the acoustic wave propagation direction of the resonator is restrained between the two side grooves, so that the quality factor of the resonator is further improved.
In some possible implementations, the side grooves are rectangular grooves extending along the perpendicular first direction.
In some possible implementations, the side grooves are arcuate grooves, and the arcuate grooves are convex to a side away from the interdigital transducer.
In some possible implementations, in a first direction perpendicular to the first direction, two ends of the side grooves are respectively flush with two ends of the plurality of interdigital electrodes; or, in the vertical first direction, two ends of the side groove respectively exceed two ends of the plurality of interdigital electrodes; to further increase the reflection efficiency of the side grooves against the energy in the acoustic wave propagation direction of the resonator.
In some possible implementations, a distance between an interdigital electrode closest to the side groove among the plurality of interdigital electrodes and the side groove is a first distance; the distance between any two adjacent interdigital electrodes is a second distance; the first distance and the second distance are equal; therefore, the bulk wave radiation of the resonator can be reduced, the energy loss is reduced, and the reflection efficiency of the side grooves on the sound waves is improved.
On this basis, in some embodiments, by setting the first distance and the second distance to each be equal to 1/4λ, λ being the wavelength corresponding to the resonance frequency of the resonator (hereinafter, this is the same); the sound wave (namely, the incident wave) emitted from the interdigital transducer and the sound wave (namely, the reflected wave) reflected by the side grooves are in phase, and constructive interference can occur between the sound wave and the reflected wave, so that the reflection efficiency can be highest.
In some possible implementations, the width of the side grooves along the first direction is equal to 1/4λ to λ; specifically, on the basis of guaranteeing the reflection of the side grooves on the energy in the acoustic wave propagation direction of the resonator, the width of the side grooves along the first direction is larger than or equal to 1/4 lambda, so that the side grooves can be guaranteed to have good process realizability, namely the manufacturing process precision requirement is low; by providing the side grooves with a width in the first direction of λ or less, the influence on the performance of the resonator can be reduced.
In some possible implementations, the piezoelectric substrate includes a base, and a trap layer, an oxide layer, and a piezoelectric layer sequentially disposed on the base; the depth of the side grooves may sequentially penetrate through one or more layers of structures in the piezoelectric substrate from top to bottom. For example, the depth of the side grooves may extend only through the piezoelectric layer; for another example, the depth of the side trenches may extend through the piezoelectric layer and the oxide layer; as another example, the depth of the side trenches may extend through the piezoelectric layer, the oxide layer, and the trap layer; as another example, the depth of the side grooves may extend through the entire piezoelectric substrate.
In this case, compared with the arrangement mode that the side grooves penetrate through the multilayer structure in the piezoelectric substrate, the manufacture process is difficult and the cost is high, the arrangement mode that the side grooves only penetrate through the piezoelectric layer is adopted, the manufacture process can be simplified, and the manufacture cost is reduced.
In some possible implementations, the piezoelectric substrate includes a base and a piezoelectric layer disposed on the base; in this case, the depth of the side groove may penetrate only the piezoelectric layer, may penetrate the entire piezoelectric substrate; of course, to simplify the fabrication process and reduce the fabrication cost, the depth of the side grooves may be generally set to penetrate only the piezoelectric layer.
In some possible implementations, the resonator further includes a first piston structure and a second piston structure; the first piston structure is arranged on the end surface of one side of the first interdigital electrode, which is close to the second bus bar; the second piston structure is arranged on the end surface of the second interdigital electrode, which is close to one side of the first bus bar. In this case, in the vertical acoustic wave propagation direction, a low acoustic velocity region can be formed at the installation position of the piston structure, so that resonance formed by reflection of a transverse wave between the first bus bar and the second bus bar can be suppressed, and the purpose of reducing the spurious mode of the resonator can be achieved.
In some possible implementations, the piezoelectric substrate is further provided with a first transverse groove; the first transverse groove is positioned in the area between the first interdigital electrode and the second bus bar so as to further reduce the stray mode of the resonator. In this case, by the first transverse groove arrangement, the displacement field can be changed by changing the electric field distribution of the resonator, thereby achieving the purpose of reducing the spurious mode (spirious mode) of the resonator.
In some possible implementations, the first lateral groove extends along the first direction and does not overlap the second interdigital electrodes, i.e., the first lateral groove is located in a region between two adjacent second interdigital electrodes, thereby facilitating the fabrication of the first lateral groove.
In some possible implementations, the piezoelectric substrate is further provided with a second lateral groove; the second transverse groove is positioned in a region between the second interdigital electrode and the first bus bar so as to further reduce the stray mode of the resonator. In this case, by setting the second transverse grooves, the displacement field can be changed by changing the electric field distribution of the resonator, so as to achieve the purpose of reducing the spurious mode (spurious mode) of the resonator.
In some possible implementations, the second lateral grooves extend along the first direction and do not overlap the first interdigital electrodes, that is, the second lateral grooves are located in a region between two adjacent first interdigital electrodes, so that processing and manufacturing of the second lateral grooves are facilitated.
In some possible implementations, the distance between the first lateral trench and the first interdigitated electrode is greater than 1/4 λ; therefore, the problem of large transverse wave disturbance caused by too small distance between the first transverse groove and the first interdigital electrode is solved, and the suppression effect on the stray mode of the resonator is further improved.
In some possible implementations, a distance between the second lateral groove and the second interdigital electrode is greater than 1/4 λ; therefore, the problem of large transverse wave disturbance caused by too small distance between the second transverse groove and the second interdigital electrode is solved, and the suppression effect on the stray mode of the resonator is further improved.
In some possible implementations, the width of the first lateral groove along the vertical first direction is equal to 1/4λ to λ; specifically, on the basis of ensuring the suppression effect of the first transverse groove on the stray mode of the resonator, the width of the first transverse groove along the second direction is larger than or equal to 1/4λ, so that the first transverse groove has good process realizability, namely the requirement on manufacturing process precision is low; the first transverse groove can be ensured to have better process realizability, namely, the manufacturing process has low precision requirement; by providing the width of the first lateral groove in the second direction to be less than or equal to λ, the influence on the performance of the resonator can be reduced.
In some possible implementations, the width of the second lateral groove along the vertical first direction is equal to 1/4λ to λ; specifically, on the basis of ensuring the suppression effect of the second transverse groove on the stray mode of the resonator, the second transverse groove can be ensured to have better process realizability, namely low manufacturing process precision requirement by setting the width of the second transverse groove along the second direction to be more than or equal to 1/4λ; the second transverse groove can be ensured to have better process realizability, namely, the manufacturing process has low precision requirement; by providing the second lateral groove with a width in the second direction that is less than or equal to λ, the influence on the performance of the resonator can be reduced.
In some possible implementations, two ends of the side groove are respectively communicated with the first transverse groove and the second transverse groove at the same side of the plurality of interdigital electrodes; to further reduce the size of the resonator, to improve the quality factor of the resonator, and to improve the suppression of spurious modes.
In some possible implementations, the resonator is a surface acoustic wave resonator.
The embodiments of the present application also provide an electronic device comprising a resonator as provided in any one of the possible implementations described above.
In some possible implementations, the electronic device includes a filter built with the resonator described above.
The embodiment of the application also provides electronic equipment, which comprises a printed circuit board and the electronic device which is connected with the printed circuit board and is provided in any one of the possible modes.
Fig. 1 is a schematic diagram of an electronic device according to an embodiment of the present application;
fig. 2 is a schematic structural diagram of a resonator according to an embodiment of the present application;
FIG. 3 is a schematic cross-sectional view of FIG. 2 taken along the OO' position;
fig. 4 is a schematic structural diagram of a resonator according to an embodiment of the present application;
FIG. 5 is a schematic cross-sectional view of FIG. 4 taken along the line AA';
FIG. 6 is a diagram illustrating a vibration displacement simulation of a resonator according to the related art;
FIG. 7 is a diagram illustrating a simulation of vibration displacement of a resonator according to an embodiment of the present application;
fig. 8a is a schematic structural diagram of a resonator according to an embodiment of the present application;
fig. 8b is a schematic structural diagram of a resonator according to an embodiment of the present application;
fig. 8c is a schematic structural diagram of a resonator according to an embodiment of the present application;
fig. 9 is a schematic structural diagram of a resonator according to an embodiment of the present application;
fig. 10 is a schematic structural diagram of a resonator according to an embodiment of the present application;
fig. 11 is a schematic structural diagram of a resonator according to an embodiment of the present application;
fig. 12 is a schematic structural diagram of a resonator according to an embodiment of the present application;
fig. 13 is a schematic structural diagram of a resonator according to an embodiment of the present application;
fig. 14 is a schematic structural diagram of a resonator according to an embodiment of the present application;
FIG. 15 is an admittance curve of a resonator according to an embodiment of the present application;
fig. 16 is an admittance curve of a resonator according to an embodiment of the present application.
For the purpose of making the objects, technical solutions and advantages of the present application more apparent, the technical solutions of the present application will be clearly described below with reference to the accompanying drawings in which it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
The terms "first," "second," and the like in the description and in the claims and drawings are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or order. "connected," "coupled," and the like, are used to indicate interworking or interaction between different components, and may include direct coupling or indirect coupling via other components. "at least one" means one or more, and "a plurality" means two or more. Furthermore, the terms "comprise" and "have," as well as any variations thereof, are intended to cover a non-exclusive inclusion, such as a series of steps or elements. The method, system, article, or apparatus is not necessarily limited to those explicitly listed but may include other steps or elements not explicitly listed or inherent to such process, method, article, or apparatus. "upper", "lower", "left", "right", etc. are used merely with respect to the orientation of the components in the drawings, these directional terms are relative terms, which are used for description and clarity with respect thereto, and which may vary accordingly depending on the orientation in which the components are placed in the drawings.
The embodiment of the application provides electronic equipment, which is provided with a printed circuit board (printed circuit board, PCB) and an electronic device connected with the printed circuit board; wherein a resonator is arranged in the electronic device; the application does not limit the setting form of the electronic device; illustratively, in some possible implementations, the electronic device may be a filter, a sensor, a transformer, or the like, product or component capable of generating a resonant frequency.
The application does not limit the specific setting form of the electronic equipment; for example, the electronic device may be an electronic product such as a television, a mobile phone, a television, a tablet computer, a notebook, a vehicle-mounted computer, a smart watch, a smart bracelet, and a satellite communication device.
The application does not limit the type of the resonator arranged in the electronic device; for example, the resonator may be a surface acoustic wave (surface acoustic wave, SAW) resonator, lamb wave (lamb) resonator, microelectromechanical system (micro-electro-mechanical system, MEMS) resonator, or the like; the following examples are illustrative of the resonator using SAW resonators as examples.
Illustratively, as shown in fig. 1, in some possible implementations, the electronic device 001 may include a processor 01, and a memory 02 and a transceiver 03 connected to the processor 01; the transceiver 03 is provided with a filter 031 constructed by using a resonator.
The resonator adopted in the electronic equipment provided by the embodiment of the application has the advantages of small size and high quality factor, so that the performance of the electronic equipment can be improved.
The structure of the resonator provided by the embodiment of the application is specifically described below.
As shown in fig. 2, an embodiment of the present application provides a resonator including a piezoelectric substrate 1 and an interdigital transducer 2 (interdigital transducer, IDT) provided on the piezoelectric substrate 1.
The specific arrangement form of the piezoelectric substrate 1 is not limited in the present application; illustratively, in some possible implementations, as shown in connection with fig. 2 and 3 (the cross-sectional schematic view of fig. 1 along OO' position), the piezoelectric substrate 1 may include a base 11 and sequentially disposed onA trap layer 12 (trap, TR), an oxide layer 13, a piezoelectric layer 14 on a substrate 11, and an interdigital transducer 2 are disposed on the surface of the piezoelectric layer 14. Wherein the substrate 11 may be a silicon wafer, a quartz wafer, or the like, the material forming the trap layer 12 may include polysilicon, and the material forming the oxide layer 13 may include silicon dioxide (SiO 2 ) Forming the piezoelectric layer 14 may include one or more of Lithium Niobate (LN), lithium tantalate (lithium tantalite, LT), and the like.
Of course, in other possible implementations, the piezoelectric substrate 1 may include a base 11 and a piezoelectric layer 14 disposed on the base 11, and the interdigital transducer 2 is disposed on a surface of the piezoelectric layer 14. Among them, the substrate 11 may employ a silicon wafer, a quartz wafer, or the like, and the formation of the piezoelectric layer 14 may include one or more of piezoelectric materials such as Lithium Niobate (LN), lithium tantalate (lithium tantalite, LT), and the like.
Referring to fig. 2, the interdigital transducer 2 includes a first bus bar 21, a second bus bar 22, and a plurality of interdigital electrodes 20 (interdigital electrode) arranged in parallel. Illustratively, the first bus bar 21, the second bus bar 22, and the interdigital electrode 20 may be made of conductive metal materials such as aluminum and copper, which are not limited in the present application.
Hereinafter, for the sake of clarity, a specific structure of the resonator will be described, in which the direction in which the plurality of interdigital electrodes 20 are juxtaposed is defined as a first direction XX ', and the direction in which the plurality of interdigital electrodes 20 are juxtaposed is defined as a second direction YY'.
Referring to fig. 2, the first and second bus bars 21 and 22 are distributed on both sides of the plurality of interdigital electrodes 20 in the second direction YY'; the plurality of interdigital electrodes 20 includes first interdigital electrodes 201 and second interdigital electrodes 202 alternately arranged in sequence in a first direction XX'; the first interdigital electrode 201 is connected to the first bus bar 21, and the second interdigital electrode 202 is connected to the second bus bar 22. In this case, during operation of the resonator, the interdigital transducer 2 can convert an input electrical signal into acoustic wave vibration through the first interdigital electrode 201 by using the inverse piezoelectric effect of the piezoelectric material in the piezoelectric layer 14, and convert the acoustic wave vibration back into an electrical signal through the second interdigital electrode 202 by using the positive piezoelectric effect, thereby realizing acousto-electric transduction.
On the basis of this, reference is made to fig. 2 and 3 (schematic cross-sectional view of fig. 2 along OO 'position), in which resonator the piezoelectric substrate 1 is provided with lateral grooves 3 (grooves) on at least one side of a plurality of interdigital electrodes 20 (also known as interdigital transducers 2) along the first direction XX'; in this case, the resonator generates acoustic impedances with larger difference at the positions of the side grooves 3, so that total reflection occurs when the acoustic waves propagate to the positions of the side grooves 3, thereby reducing energy loss of the resonator in the acoustic wave propagation direction at the resonance frequency and further improving the quality factor of the resonator.
It should be noted that, the provision of the side grooves 3 on at least one side of the plurality of interdigital electrodes 20 means that, as shown in fig. 2 and 3, the side grooves 3 (refer to fig. 2) may be provided on one side (e.g., the left side or the right side) of the plurality of interdigital electrodes 20, or, as shown in fig. 4 and 5 (a schematic cross-sectional view along the AA' position in fig. 4), the side grooves 3 may be provided on both sides (the left side and the right side) of the plurality of interdigital electrodes 20, respectively, and the energy in the acoustic wave propagation direction of the resonator may be reflected by the side grooves 3 on both sides, and the energy in the acoustic wave propagation direction of the resonator may be confined between the two side grooves 3, thereby further improving the quality factor of the resonator.
Fig. 6 is a vibration displacement simulation diagram of a resonator employing a plurality of interdigital electrodes 20 with reflectors disposed on both sides thereof in the related art, and fig. 7 is a vibration displacement simulation diagram of a resonator employing a plurality of interdigital electrodes 20 with single side grooves 3 disposed on both sides thereof, respectively, in accordance with an embodiment of the present application; as can be seen from fig. 6, there is a significant vibrational displacement of the reflector regions on either side of the interdigital transducer region in the Z direction (i.e., the directions perpendicular to XX 'and YY'); in contrast, as can be seen from fig. 7, the vibration displacement in the Z direction is significantly reduced outside the side grooves 3 (i.e., on the side away from the interdigital transducer region), thereby further confirming that the reflection efficiency of the side grooves 3 employed in the present application for acoustic wave energy is higher than that of the reflector.
In addition, since a plurality of reflective gratings are provided in the reflector, the size of the resonator may be increased; in contrast, the use of the side grooves 3 in the embodiments of the present application increases the reflection efficiency (quality factor) of the resonator while also reducing the size of the resonator.
Illustratively, taking the interdigital transducer 2 provided with 80 pairs of interdigital electrodes 20 (i.e., 40 first interdigital electrodes 201 and 40 second interdigital electrodes 202) as an example, compared with the resonator provided with reflectors employing 50 pairs of reflective gate electrodes on the left and right sides of the plurality of interdigital electrodes 20, the resonator provided with side grooves 3 on the left and right sides of the plurality of interdigital electrodes 20 in the present application (i.e., the side grooves 3 are used to replace the reflectors) can be reduced in size by more than 60%, in which case more resonators can be fabricated using the same wafer, and thus the cost can be reduced.
In addition, in the case where the side grooves 3 are provided on one side of the plurality of interdigital electrodes 20 in the present application, as shown in fig. 2, the side grooves 3 may be provided on one side of the plurality of interdigital electrodes 20 and the reflector 4 may be provided on the opposite side, so that energy (e.g., surface acoustic wave) in the acoustic wave propagation direction of the resonator is reflected by the side grooves 3 and the reflector 4 to confine the energy in the acoustic wave propagation direction of the resonator between the side grooves 3 and the reflector 4 to ensure the quality factor of the resonator.
The specific arrangement of the side grooves 3 will be further described below.
The depth of the side grooves 3 is not limited in the present application, and may be set as needed in practice.
Taking the piezoelectric substrate 1 as an example of a multilayer structure including the base 11, the trap layer 12, the oxide layer 13, and the piezoelectric layer 14, the depth of the side groove 3 may sequentially penetrate one or more layers of the piezoelectric substrate 1 from top to bottom.
For example, in some possible implementations, as shown in fig. 5, the depth of the side grooves 3 may extend only through the piezoelectric layer 14.
As another example, in some possible implementations, as shown in fig. 8a, the depth of the side grooves 3 may extend through the piezoelectric layer 14 and the oxide layer 13.
As another example, in some possible implementations, as shown in fig. 8b, the depth of the side trench 3 may extend through the piezoelectric layer 14, the oxide layer 13, and the trap layer 12.
As another example, in some possible implementations, as shown in fig. 8c, the depth of the side trench 3 may extend through the entire piezoelectric substrate 1, i.e., the depth of the side trench 3 extends through the piezoelectric layer 14, the oxide layer 13, the trap layer 12, the base 11. It will be understood here that, of course, in the case where the side grooves 3 extend deeply throughout the piezoelectric substrate 1, it should be ensured that the arrangement of the side grooves 3 does not affect the strength of the resonator, i.e., that the substrate 11 has sufficient supporting strength for the entire resonator.
Compared to the above-mentioned multilayer structure (as shown in fig. 8a, 8b, 8 c) in which the side grooves 3 penetrate the piezoelectric substrate 1, the arrangement of the side grooves 3 in fig. 5 penetrating only the piezoelectric layer 14 can simplify the manufacturing process and reduce the manufacturing cost.
The number of side grooves 3 provided on a single side (left or right) of the plurality of interdigital electrodes 20 is not limited in the present application; for example, as shown with reference to fig. 2, 4, 1 side groove 3 may be provided on a single side (left or right) of the plurality of interdigital electrodes 20 in the first direction XX'; for another example, referring to fig. 9, a plurality of (including but not limited to 2) side grooves 3 may be arranged side by side in the first direction XX' on one side of the plurality of interdigital electrodes 20.
The present application is not limited in the arrangement shape of the side grooves 3; of course, in order to ensure an efficient reflection of energy in the acoustic wave propagation direction of the resonator by the side grooves 3, it is possible to provide that the side grooves 3 are distributed along the second direction YY'.
For example, in some possible implementations, as shown in fig. 4, 9, 10, the side grooves 3 may be rectangular grooves extending in the second direction YY'. Schematically, as shown in fig. 4, the rectangular groove may be a single rectangular groove extending in the second direction YY'; as shown in fig. 10, the rectangular groove includes a plurality of rectangular grooves extending in the second direction YY' and arranged in parallel.
As another example, in some possible implementations, as shown in fig. 11 and 12, the side grooves 3 are arc grooves distributed along the second direction YY ', and the arc grooves 3 are convex toward a side away from the interdigital transducer 2 along the first direction XX'. Schematically, as shown in fig. 11, the arc-shaped grooves may be single arc-shaped grooves distributed along the second direction YY'; as shown in fig. 12, the arc-shaped groove may include a plurality of arc-shaped grooves distributed in the second direction YY'.
On this basis, in order to further improve the reflection efficiency of the side grooves 3 on the energy in the acoustic wave propagation direction of the resonator, in some possible implementations, as shown in fig. 4 to 12, the side grooves 3 may be disposed along the second direction YY', and both ends of the side grooves 3 are respectively flush with both ends of the plurality of interdigital electrodes 20 or extend beyond both ends of the plurality of interdigital electrodes 20; that is, the upper ends of the side grooves 3 are flush with or protrude from the upper ends of the first interdigital electrodes 201, and the lower ends of the side grooves 3 are flush with or protrude from the lower ends of the second interdigital electrodes 202.
In this case, during the operation of the resonator, the entire energy of the entire region of the plurality of interdigital electrodes 20 (including 201, 202) between the first bus bar 21 and the second bus bar 22 in the propagation direction (i.e., XX' direction) of the generated acoustic wave can be reflected by the side grooves 3, thereby improving the reflection efficiency and thus the quality factor of the resonator.
In addition, in the case of using a rectangular groove for the side groove 3, the following is adopted:
in some possible implementations, referring to fig. 4, a first distance d1 between an interdigital electrode 20 closest to a side groove 3 of the plurality of interdigital electrodes 20 and the side groove 3 may be set equal to a second distance d2 between any two adjacent interdigital electrodes 20, that is, d1=d2, so as to reduce bulk wave radiation of the resonator, reduce energy loss, and further improve reflection efficiency of the side groove 3 on acoustic waves.
Illustratively, in some possible implementations d1=d2=1/4λ may be set; wherein λ is a wavelength corresponding to a resonant frequency of the resonator, and hereinafter, λ is the same, and will not be described again; as is known from bragg's law, when d1=d2=1/4λ (i.e., 1/4λ pitch) is selected, the acoustic wave (i.e., incident wave) emitted from the interdigital transducer 2 is in phase with the acoustic wave (i.e., reflected wave) reflected by the side grooves 3, and constructive interference occurs between the two, so that the reflection efficiency can be maximized.
It should be noted that, for the first distance d1 and the second distance d2 to be equal, it does not absolutely mean that the first distance d1 and the second distance d2 are completely opposite, and it is understood that a machining error inevitably exists in the manufacturing process, so in practice, the first distance d1 and the second distance d2 may have a certain difference due to the machining error, but should be regarded as equal; similarly, in the embodiments of the present application, the "equal to", "yes" and the like related to the description of the size should be considered in consideration of the existence of the machining error, and the description will not be repeated.
In some possible implementations, referring to fig. 4, the width w1 of the side groove 3 in the first direction XX' may be set to be 1/4λ to λ.
By setting the width w1 of the side groove 3 along the first direction XX' to be larger than or equal to 1/4λ on the basis of guaranteeing the reflection of the side groove 3 to the energy in the acoustic wave propagation direction of the resonator, the side groove 3 can be guaranteed to have better process realizability, namely, the manufacturing process precision requirement is low; by providing the side groove 3 with a width w1 in the first direction XX' that is less than or equal to λ, the influence on the performance of the resonator can be reduced.
In addition, in some possible implementations, as shown in fig. 13, a first piston structure P1 (piston) may be provided at an end surface of the first interdigital electrode 201 on the side near the second bus bar 22, and a second piston structure P2 may be provided at an end surface of the second interdigital electrode 202 on the side near the first bus bar 21; in this case, in the vertical acoustic wave propagation direction (i.e., YY' direction), a low acoustic velocity region can be formed at the position where the piston structure is disposed, so that resonance formed by reflection of a transverse wave between the first bus bar 21 and the second bus bar 22 can be suppressed, and the purpose of reducing the spurious mode (spurious mode) of the resonator can be achieved.
Illustratively, the first piston structure P1 and the second piston structure P2 may be made of conductive metal materials such as aluminum and copper, but the present application is not limited thereto.
On this basis, in some possible implementations, as shown with reference to fig. 14, a first lateral groove G1 and a second lateral groove G2 may be provided on the piezoelectric substrate 1; wherein the first lateral groove G1 is located in a region between the first interdigital electrode 201 and the second bus bar 22; of course, to facilitate the fabrication of the second lateral groove G2, the first lateral groove G1 may be provided to extend in the first direction XX' without overlapping the second interdigital electrode 202. Correspondingly, the second transverse groove G2 is located in the region between the second interdigital electrode 202 and the first bus bar 21; the second lateral groove G2 may also be provided to extend in the first direction XX' and not overlap the first interdigital electrode 201. In this case, by the arrangement of the first and second transverse grooves G1 and G2, the displacement field can be changed by changing the electric field distribution of the resonator, thereby achieving the purpose of reducing the spurious mode (spurious mode) of the resonator.
The above-mentioned "the first lateral groove G1 extends in the first direction XX 'and does not overlap with the second interdigital electrode 22" means that the first lateral groove G1 is provided between the first interdigital electrode 201 and the second bus bar 22 in a region other than the position where the second interdigital electrode 22 is located in the first direction XX'. Correspondingly, the second lateral groove G2 is provided between the second interdigital electrode 202 and the first bus bar 21 in a region other than the first interdigital electrode 21 in the first direction XX'.
Fig. 15 is an admittance curve of a resonator in the case where the first piston structure P1 and the second piston structure P2 are provided; fig. 16 is an admittance curve of a resonator in the case where the first piston structure P1, the second piston structure P2, the first lateral groove G1, the second lateral groove G2 are provided; as can be seen by comparing fig. 15 and fig. 16, by the arrangement of the first piston structure P1 and the second piston structure P2 in fig. 15, most of the spurious modes of the resonator can be reduced, but some spurious modes still exist and are not suppressed; in contrast, the admittance curve in fig. 16 is significantly suppressed compared with the admittance curve in fig. 15, and only two weaker spurious modes remain in the admittance curve in fig. 16, that is, the suppression effect of the first lateral grooves G1 and the second lateral grooves G2 on the spurious modes of the resonator is further verified.
Other related arrangements of the first and second lateral grooves G1 and G2 will be specifically described below.
In the present application, the depth of the first transverse groove G1 and the second transverse groove G2 is not limited, and may be actually set according to needs; reference may be made specifically to the aforementioned depth setting for the side grooves 3, and no further description is given here.
The arrangement shape of the first and second lateral grooves G1 and G2 is not limited in the present application, and may be rectangular or arc-shaped. Illustratively, in some possible implementations, referring to fig. 12, the first and second lateral grooves G1, G2 may include a plurality of rectangular grooves distributed along the first direction XX'.
In the case where the first and second lateral grooves G1 and G2 are rectangular grooves:
in some possible implementations, referring to fig. 14, a distance L1 between the first lateral groove G1 and the first interdigital electrode 201 may be set to be greater than 1/4λ, and a distance L2 between the second lateral groove G2 and the second interdigital electrode 202 is set to be greater than 1/4λ, so that the problem of large lateral wave disturbance caused by too small distances L1, L2 is improved, and the suppression effect on the spurious mode (spurious mode) of the resonator is further improved.
Of course, the distance L1 between the first lateral groove G1 and the first interdigital electrode 201 may be equal to or different from the distance L2 between the second lateral groove G2 and the second interdigital electrode 202, which is not limited in the present application; in some possible implementations, l1=l2 may be set.
In some possible implementations, referring to fig. 14, the first and second lateral grooves G1 and G2 may be provided to have a width w of 1/4λ to λ in the second direction YY'.
The schematic way is that on the basis of ensuring the suppression effect of the transverse grooves (G1, G2) on the stray mode of the resonator, the width w of the transverse grooves (G1, G2) along the second direction YY' is larger than or equal to 1/4 lambda, so that the transverse grooves (G1, G2) can be ensured to have better process realizability, namely the manufacturing process precision requirement is low; by providing the lateral grooves (G1, G2) with a width w in the second direction YY' that is less than or equal to λ, the effect on the performance of the resonator can be reduced.
In addition, in order to effectively reduce the size of the resonator, improve the quality factor of the resonator, and simultaneously effectively improve the suppression of the spurious modes, as shown in fig. 14, in some possible implementations, two ends of the side groove 3 may be disposed to be respectively communicated with the first lateral groove G1 and the second lateral groove G2 on the same side (left side, right side) of the plurality of interdigital electrodes 2; that is, the upper ends of the side grooves 3 located on the left side of the plurality of interdigital electrodes 2 communicate with the left side of the second lateral groove G2, the lower ends communicate with the left side of the first lateral groove G1, the upper ends of the side grooves 3 located on the right side of the plurality of interdigital electrodes 2 communicate with the right side of the second lateral groove G2, and the lower ends communicate with the right side of the first lateral groove G1.
The foregoing is merely illustrative of the present application, and the present application is not limited thereto, and any person skilled in the art will readily recognize that variations or substitutions are within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (20)
- The resonator is characterized by comprising a piezoelectric substrate and an interdigital transducer arranged on the piezoelectric substrate;the interdigital transducer comprises a plurality of interdigital electrodes which are arranged in parallel; the parallel arrangement direction of the plurality of interdigital electrodes is a first direction;the piezoelectric substrate is provided with a side groove along the first direction on at least one side of the plurality of interdigital electrodes.
- A resonator according to claim 1, characterized in that,the piezoelectric substrate is provided with the side grooves along the first direction and on two sides of the interdigital electrodes.
- Resonator according to claim 1 or 2, characterized in that,the side grooves are rectangular grooves extending in a direction perpendicular to the first direction.
- Resonator according to claim 1 or 2, characterized in that,the side grooves are arc grooves, and the arc grooves are protruded to one side far away from the interdigital transducer.
- A resonator according to any of claims 1-4, characterized in that,in the direction vertical to the first direction, two ends of the side groove are respectively flush with two ends of the interdigital electrodes;alternatively, in a direction perpendicular to the first direction, both ends of the side grooves respectively extend beyond both ends of the plurality of interdigital electrodes.
- The resonator according to any of claims 1-3, 5, characterized in that,the distance between the interdigital electrode closest to the side groove and the side groove in the plurality of interdigital electrodes is a first distance; the distance between any two adjacent interdigital electrodes is a second distance;the first distance and the second distance are equal.
- The resonator according to claim 6, characterized in that,the first distance and the second distance are both equal to 1/4 lambda; and lambda is the wavelength corresponding to the resonant frequency of the resonator.
- A resonator according to any of claims 1-7, characterized in that,the width of the side groove along the first direction is equal to 1/4 lambda-lambda; and lambda is the wavelength corresponding to the resonant frequency of the resonator.
- A resonator according to any of claims 1-8, characterized in that,the interdigital transducer further comprises a first bus bar and a second bus bar;the plurality of interdigital electrodes comprise first interdigital electrodes and second interdigital electrodes which are alternately arranged in sequence; the first bus bar and the second bus bar are distributed on two sides of the interdigital electrodes along the vertical first direction; the first interdigital electrode is connected with the first bus bar, and the second interdigital electrode is connected with the second bus bar;the piezoelectric substrate is also provided with a first transverse groove, and the first transverse groove is positioned in a region between the first interdigital electrode and the second bus bar.
- The resonator according to claim 9, characterized in that,and a second transverse groove is further formed in the piezoelectric substrate and is positioned in a region between the second interdigital electrode and the first bus bar.
- The resonator according to claim 10, characterized in that,the first transverse groove extends along the first direction and does not overlap the second interdigital electrode;the second lateral groove extends along the first direction and does not overlap the first interdigital electrode.
- A resonator according to any of claims 9-11, characterized in that,the distance between the first transverse groove and the first interdigital electrode is greater than 1/4 lambda; and lambda is the wavelength corresponding to the resonant frequency of the resonator.
- A resonator according to any of claims 10-12, characterized in that,the distance between the second transverse groove and the second interdigital electrode is greater than 1/4 lambda; and lambda is the wavelength corresponding to the resonant frequency of the resonator.
- A resonator according to any of claims 9-13, characterized in that,the width of the first transverse groove along the direction perpendicular to the first direction is equal to 1/4λ - λ; and lambda is the wavelength corresponding to the resonant frequency of the resonator.
- Resonator according to any of claims 10-14, characterized in that,the width of the second transverse groove along the direction perpendicular to the first direction is equal to 1/4λ - λ; and lambda is the wavelength corresponding to the resonant frequency of the resonator.
- Resonator according to any of claims 10-15, characterized in that,and two ends of the side groove are respectively communicated with the first transverse groove and the second transverse groove on the same side of the interdigital electrodes.
- A resonator according to any of claims 1-16, characterized in that,the resonator further comprises a first piston structure and a second piston structure;the first piston structure is arranged on the end surface of one side of the first interdigital electrode, which is close to the second bus bar;the second piston structure is arranged on the end surface of the second interdigital electrode, which is close to one side of the first bus bar.
- The resonator according to any of claims 1-17, characterized in that the resonator is a surface acoustic wave resonator.
- A filter comprising a resonator as claimed in any one of claims 1 to 18.
- An electronic device comprising a printed wiring board and the filter of claim 19 connected to the printed wiring board.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/CN2021/083613 WO2022204876A1 (en) | 2021-03-29 | 2021-03-29 | Resonator, filter, and electronic device |
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| CN116686217A true CN116686217A (en) | 2023-09-01 |
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| CN202180089501.XA Pending CN116686217A (en) | 2021-03-29 | 2021-03-29 | Resonator, filter and electronic device |
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| WO (1) | WO2022204876A1 (en) |
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| CN116505906A (en) * | 2023-04-17 | 2023-07-28 | 无锡市好达电子股份有限公司 | Surface acoustic wave resonator |
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| JP2547980B2 (en) * | 1984-01-09 | 1996-10-30 | 日本電波工業 株式会社 | Ultrasonic transducer and method of manufacturing the same |
| JP4063000B2 (en) * | 2001-08-14 | 2008-03-19 | 株式会社村田製作所 | Edge reflection type surface acoustic wave filter |
| CN205017279U (en) * | 2015-10-28 | 2016-02-03 | 江苏声立传感技术有限公司 | High Q value of being applied to wireless temperature sensor is single -ended to SAW resonator |
| SG10201911416RA (en) * | 2018-12-03 | 2020-07-29 | Skyworks Solutions Inc | Acoustic Wave Device With Transverse Spurious Mode Suppression |
| US11177791B2 (en) * | 2019-02-01 | 2021-11-16 | Qorvo Us, Inc. | High quality factor transducers for surface acoustic wave devices |
| CN112491379B (en) * | 2020-10-21 | 2024-03-22 | 电子科技大学 | Surface acoustic wave resonator with phonon crystal reflector |
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