CN116707482A - Resonator for inhibiting transverse mode and elastic wave device - Google Patents
Resonator for inhibiting transverse mode and elastic wave device Download PDFInfo
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- 230000002401 inhibitory effect Effects 0.000 title abstract description 6
- 239000000758 substrate Substances 0.000 claims abstract description 23
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 13
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 9
- 229910052710 silicon Inorganic materials 0.000 claims description 9
- 239000010703 silicon Substances 0.000 claims description 9
- 229910052814 silicon oxide Inorganic materials 0.000 claims description 5
- 229910052581 Si3N4 Inorganic materials 0.000 claims description 4
- 229910003460 diamond Inorganic materials 0.000 claims description 4
- 239000010432 diamond Substances 0.000 claims description 4
- 239000010453 quartz Substances 0.000 claims description 4
- 229910052594 sapphire Inorganic materials 0.000 claims description 4
- 239000010980 sapphire Substances 0.000 claims description 4
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims description 4
- 229910010271 silicon carbide Inorganic materials 0.000 claims description 4
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims description 4
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 3
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 3
- 238000010897 surface acoustic wave method Methods 0.000 abstract description 4
- 230000003071 parasitic effect Effects 0.000 abstract 1
- 238000000034 method Methods 0.000 description 9
- 238000004088 simulation Methods 0.000 description 9
- 230000001629 suppression Effects 0.000 description 9
- 239000000463 material Substances 0.000 description 8
- 230000008569 process Effects 0.000 description 6
- 235000012239 silicon dioxide Nutrition 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 4
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- 238000005516 engineering process Methods 0.000 description 3
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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
- 229910012463 LiTaO3 Inorganic materials 0.000 description 2
- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 2
- 229910052681 coesite Inorganic materials 0.000 description 2
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- 238000011161 development Methods 0.000 description 2
- -1 etc. Substances 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 230000005764 inhibitory process Effects 0.000 description 2
- 230000001902 propagating effect Effects 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- 229910052682 stishovite Inorganic materials 0.000 description 2
- 229910052905 tridymite Inorganic materials 0.000 description 2
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 description 1
- 229910002601 GaN Inorganic materials 0.000 description 1
- JMASRVWKEDWRBT-UHFFFAOYSA-N Gallium nitride Chemical compound [Ga]#N JMASRVWKEDWRBT-UHFFFAOYSA-N 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 description 1
- 229910052878 cordierite Inorganic materials 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000003989 dielectric material Substances 0.000 description 1
- JSKIRARMQDRGJZ-UHFFFAOYSA-N dimagnesium dioxido-bis[(1-oxido-3-oxo-2,4,6,8,9-pentaoxa-1,3-disila-5,7-dialuminabicyclo[3.3.1]nonan-7-yl)oxy]silane Chemical compound [Mg++].[Mg++].[O-][Si]([O-])(O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2)O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2 JSKIRARMQDRGJZ-UHFFFAOYSA-N 0.000 description 1
- KZHJGOXRZJKJNY-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Si]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O KZHJGOXRZJKJNY-UHFFFAOYSA-N 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- 229910052839 forsterite Inorganic materials 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 description 1
- FUJCRWPEOMXPAD-UHFFFAOYSA-N lithium oxide Chemical compound [Li+].[Li+].[O-2] FUJCRWPEOMXPAD-UHFFFAOYSA-N 0.000 description 1
- 229910001947 lithium oxide Inorganic materials 0.000 description 1
- HCWCAKKEBCNQJP-UHFFFAOYSA-N magnesium orthosilicate Chemical compound [Mg+2].[Mg+2].[O-][Si]([O-])([O-])[O-] HCWCAKKEBCNQJP-UHFFFAOYSA-N 0.000 description 1
- 239000000395 magnesium oxide Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000001465 metallisation Methods 0.000 description 1
- 238000010295 mobile communication Methods 0.000 description 1
- 229910052863 mullite Inorganic materials 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- BPUBBGLMJRNUCC-UHFFFAOYSA-N oxygen(2-);tantalum(5+) Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Ta+5].[Ta+5] BPUBBGLMJRNUCC-UHFFFAOYSA-N 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
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- 238000006467 substitution reaction Methods 0.000 description 1
- PBCFLUZVCVVTBY-UHFFFAOYSA-N tantalum pentoxide Inorganic materials O=[Ta](=O)O[Ta](=O)=O PBCFLUZVCVVTBY-UHFFFAOYSA-N 0.000 description 1
- 239000011800 void material Substances 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
- H03H9/25—Constructional features of resonators using surface acoustic waves
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/02535—Details of surface acoustic wave devices
- H03H9/02818—Means for compensation or elimination of undesirable effects
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/125—Driving means, e.g. electrodes, coils
- H03H9/145—Driving means, e.g. electrodes, coils for networks using surface acoustic waves
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
- Y02D30/00—Reducing energy consumption in communication networks
- Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks
Abstract
The application discloses a resonator for inhibiting transverse modes, which comprises a piezoelectric substrate and an IDT electrode arranged on the piezoelectric substrate, wherein the IDT electrode comprises a first bus bar and a second bus bar, the end parts of the first interdigital electrode and the corresponding positions of the end parts and the end parts of the second interdigital electrode are provided with widened parts, and the end parts of the second interdigital electrode and the corresponding positions of the end parts and the end parts of the first interdigital electrode are also provided with widened parts; the first bus bar and the second bus bar are formed with an intersection region, the intersection region comprises a central region and widened regions corresponding to the widened portions, the widened regions are located on two sides of the central region and have sound velocities lower than those of the central region, the root side regions corresponding to the first dummy electrodes are closer to the bus bar than the widened regions, and the root side regions have sound velocities greater than those of the widened portions. The application discloses the elastic wave device with the structure, which can effectively inhibit the transverse parasitic mode of the surface acoustic wave in the multilayer film elastic wave device by arranging the artificial finger and the widening part structure.
Description
Technical Field
The application relates to the technical field of radio frequency filters, in particular to a resonator for inhibiting a transverse mode and an elastic wave device.
Background
In the existing filter development technology, the elastic wave device based on the surface acoustic wave principle has the advantages of small volume, large bandwidth, low insertion loss, low cost and the like, is widely applied to mobile communication equipment such as telephones and the like, and along with the development of communication protocols, the requirements on radio frequency devices such as filters, diplexers and the like are higher and higher. Because electroacoustic transducers are an integral part of SAW devices, an optimally designed electroacoustic transducer is particularly important for obtaining high performance SAW devices.
Particularly in multilayer film surface acoustic wave (POI SAW) devices, unwanted transverse-mode (spurious) spurious responses generated by these spurious modes cause fluctuations within the passband, which can increase the energy loss of the SAW device, reduce the Q of the device, and affect the filter performance.
To solve these problems, in patent document CN 111758219A, in order to suppress the transverse mode ripple, suppression of the response at the upper end of the transverse mode ripple and the stop band is achieved by using an inclined IDT electrode connected in series and then connected in series with a piston (IDT end portion is widened), but there is a problem that a single piston IDT cannot independently satisfy the technical performance of the transverse mode suppression, and the process requirements are complex when processing an IDT structure of two types of technology are combined, and the input cost is high. Meanwhile, lateral suppression of the device by the inclined electrode finger structure is limited, and a larger inclination angle deteriorates the Q value of the device. There is room for an optimal design for the technology disclosed therein.
Disclosure of Invention
Aiming at the technical situation that the transverse inhibition effect is not ideal in the prior art, the application provides a resonator for inhibiting a transverse mode and an elastic wave device so as to solve the problem that the inhibition effect of a transverse stray mode in a surface acoustic wave resonator in the prior art is limited.
The following is a technical scheme of the application.
A resonator that suppresses transverse modes, comprising:
a piezoelectric substrate;
an IDT electrode arranged above the piezoelectric substrate, wherein the IDT electrode comprises a first bus bar and a second bus bar, the first bus bar extends to form a first interdigital electrode and a first dummy electrode, and the second bus bar extends to form a second interdigital electrode corresponding to the first dummy electrode and a second dummy electrode corresponding to the first interdigital electrode;
the end part of the first interdigital electrode and the position of the end part corresponding to the end part of the adjacent second interdigital electrode are provided with widened parts, and the position of the end part of the second interdigital electrode and the position of the broken part adjacent to the end part of the first interdigital electrode are also provided with widened parts; the first bus bar and the second bus bar are formed with an intersection area, the intersection area comprises a central area and widened areas corresponding to the widened parts, the widened areas are positioned at two sides of the central area, and the sound velocity of the widened areas is lower than that of the central area;
a root-side region of the first dummy electrode corresponding to the second dummy electrode, the root-side region being closer to the bus bar than the widened region, the root-side region having a sound velocity greater than the widened region. Preferably, a first gap is arranged between the first interdigital electrode and the first dummy electrode, a second gap is also arranged between the second interdigital electrode and the second dummy electrode, a crossing area corresponding to the first gap and the second gap is a gap area, and sound velocity of the gap area is higher than that of the central area.
Preferably, the first dummy electrode width and the second dummy electrode width are both identical to the central region electrode width.
Preferably, the piezoelectric substrate comprises a support substrate, a piezoelectric layer and a low sound velocity film layer arranged on the lower surface of the piezoelectric layer, wherein the low sound velocity film layer is a SiO2 film or a silicon oxide film or a silicon oxynitride film.
Preferably, the first dummy electrode and the second dummy electrode have a width in a length range of: 0.1λ to 1.5λ.
Preferably, the width of the widened electrode is a, and the width of the central area electrode is b, wherein a=1.1b to 1.4b.
Preferably, the length of the widened electrode is 0.1λ to 1λ.
Preferably, the piezoelectric layer is made of 30-60 degrees Y and is cut and spread with X to form LiTaO3.
Preferably, the IDT electrode is made of a Ti layer/Al layer from the piezoelectric body side. That is, the IDT electrode is made of two materials, ti is below, and Al is above Ti.
As a preferable scheme, a high sound velocity film layer is further arranged between the low sound velocity film layer and the supporting substrate, and the high sound velocity film layer is made of one of silicon nitride, silicon, aluminum oxide, silicon carbide, sapphire, quartz or diamond.
The application also discloses an elastic wave device, which is an acoustic surface filter device and comprises resonators connected in series or in parallel in the scheme.
The essential effects of the application include:
1. the first bus bar and the second bus bar extend out of the first dummy electrode and the second dummy electrode, are arranged corresponding to the interdigital electrodes, form a matching structure of the dummy electrode and the widening (hammer) of the tail end of the point electrode (the first electrode or the second electrode), and form a root side area, and the sound velocity of the side root area is close to that of the central area and higher than that of the widening area;
2. a first gap is arranged between the first interdigital electrode and the first dummy electrode, a second gap is also arranged between the second interdigital electrode and the second dummy electrode, a corresponding crossing area of the first gap and the second gap is a gap area, and sound velocity of the gap area is higher than that of the central area. The relation between the sound velocity of the central region, the sound velocity of the widened part, the sound velocity of the gap region and the sound velocity of the root side region is set, so that the attenuation of the transverse mode ripple and the response at the stop band end is realized;
3. the suppression structure of the application adds a widened part (hammer) only in the traditional electrode structure, and has a simple structure compared with an inclined IDT. Compared with a piston (piston) structure, the piston structure can be realized after only one layer of metal is needed, so that the piston structure is easier to realize and the cost is reduced;
4. in the first gap region D1 and the second gap region D2, a high sound velocity region is formed, so that a transverse mode can be effectively suppressed, which is a main setting purpose of the present application that dummy electrodes and gaps are correspondingly formed between the dummy electrodes and the interdigital electrodes;
5. the frequency corresponding to the highest admittance value is strongly improved by adding the high sound velocity film layer.
Drawings
Fig. 1 is a schematic front cross-sectional view of a resonator according to a first embodiment of the application;
FIG. 2 is a schematic top view of a resonator according to a first embodiment of the application;
FIG. 3 is a graph showing the results of simulation comparing the absolute values of admittance curves of the present application and conventional structures according to the first embodiment of the present application.
FIG. 4 is a graph showing the results of a comparative simulation of the real part of the admittance curve of the present application and a conventional structure according to the first embodiment of the present application.
Fig. 5 is a front cross-sectional view of an elastic wave device according to a second embodiment of the present application.
FIG. 6 is a graph showing the results of simulation comparing the absolute values of admittance curves of the present application and conventional structures according to the second embodiment of the present application.
FIG. 7 is a graph showing the results of comparative simulation of the real part of the admittance curve of the present application and the conventional structure according to the second embodiment of the present application.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present application more apparent, the technical solution will be clearly and completely described in the following in conjunction with the embodiments, and it is apparent that the described embodiments are only some embodiments of the present application, 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.
It should be understood that, in various embodiments of the present application, the sequence number of each process does not mean that the execution sequence of each process should be determined by its functions and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.
It should be understood that in the present application, "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements that are expressly listed or inherent to such process, method, article, or apparatus.
First embodiment:
the application discloses a resonator for inhibiting transverse modes, which comprises a piezoelectric substrate 1, wherein the piezoelectric substrate 1 comprises a support substrate 11 arranged at the bottom layer, a low-sound-velocity film layer 12 is arranged above the support substrate 11, and the low-sound-velocity film layer 12 is positioned on the lower surface of the piezoelectric layer 13. That is, the low acoustic velocity film layer 12 is located between the piezoelectric layer 13 and the support substrate 11. The support substrate 11 in the present application is a silicon substrate. The material of the support substrate 11 is not limited to a silicon substrate, and for example, various ceramics such as alumina, lithium tantalate, lithium niobate, quartz, etc., various ceramics such as alumina, sapphire, magnesia, silicon nitride, aluminum nitride, silicon carbide, zirconia, cordierite, mullite, steatite, forsterite, etc., dielectrics such as diamond, glass, etc., semiconductors such as gallium nitride, etc., and resins are used.
In an embodiment of the application, the piezoelectric layer 13 is a lithium tantalate layer. More specifically, the piezoelectric body for the piezoelectric layer 13 is 30 to 60 ° Y cut X propagation LiTaO 3 . In this embodiment LiTaO is propagated using 50℃Y cut X 3 Of course, 45 °, 36 °, etc. may be used.
The material of the piezoelectric layer 13 and the cutting angle are not limited to the above. A low sound velocity film layer 12 provided on the lower surface of the piezoelectric layer 13; the low acoustic velocity film layer 12 is a film having a relatively low acoustic velocity. More specifically, the acoustic velocity of the bulk wave propagating in the low acoustic velocity film layer 12 is lower than that of the bulk wave propagating in the piezoelectric layer 13. The silicon oxide constituting the low acoustic velocity film layer 12 of the present embodiment is SiO 2 . The material of the low acoustic velocity film layer 12 is not limited to the above, and for example, glass, silicon oxynitride, lithium oxide, tantalum pentoxide, or a compound obtained by adding fluorine, carbon, or boron to silicon oxide may be usedA material of a main component. In this embodiment, the low acoustic velocity film layer 12 is SiO 2 Film or silicon oxide film or silicon oxynitride film.
Referring specifically to fig. 2, the resonator further includes an IDT electrode 2 provided above the piezoelectric substrate 1, and the IDT electrode 2 is made of a Ti layer/Al layer from the piezoelectric body side. The IDT electrode 2 includes a first bus bar 21 and a second bus bar 22, the first bus bar 21 extends to form a first interdigital electrode 211 and a first dummy electrode 212, and the second bus bar 22 extends to form a second interdigital electrode 221 corresponding to the first dummy electrode 212 and a second dummy electrode 222 corresponding to the first interdigital electrode 211; the end portion of the first interdigital electrode 211 is widened, and the positions of the widened end portion and the adjacent second interdigital electrode 221 are widened to form a widened portion 3, and similarly, the end portion of the second interdigital electrode 221 is widened and the position area of the first interdigital electrode 211 adjacent to the end portion is widened to form a widened portion area, the two area portions jointly form a widened portion area, and the first bus bar 21 and the second bus bar 22 are formed with an intersection area, and the intersection area comprises a central area B, a widened area C corresponding to the widened portion, and a root side area E and a gap area D which are described below. The widened region C is located on both sides of the center region B and has a sound velocity lower than that of the center region B, and the root side regions E corresponding to the first and second dummy electrodes 212 (222) are closer to the bus bar than the widened region C are, and have a sound velocity higher than that of the widened region C. A first gap D2 is disposed between the first interdigital electrode 211 and the second dummy electrode 222, a second gap D1 is also disposed between the second interdigital electrode 221 and the first dummy electrode 212, a crossing region corresponding to the first gap D2 and the second gap D1 is a gap region D, and the velocity of sound in the gap region D is higher than that in the central region B.
As shown in fig. 2, the IDT electrode has a first bus bar 21, a second bus bar 22, and reflection grids 23 on both sides of the first and second bus bars, the first bus bar 21 and the second bus bar 22 being opposed to each other. One end of each of the plurality of first interdigital electrodes 211 is connected to the first bus bar 21. One end of each of the plurality of second interdigital electrodes 221 is connected to the second bus bar 22. The plurality of first interdigital electrodes 211 and the plurality of second interdigital electrodes 221 are alternately inserted into each other to form intersections. The corresponding dummy electrodes also form intersection regions. And forming a plurality of widened edge areas, called widened hammers, at the tail ends of the first interdigital electrodes and the second interdigital electrodes, and performing widening treatment on electrode parts adjacent to the widened areas to form widened parts, so that widened C1 areas of the first interdigital electrode end parts and corresponding parts and widened C2 areas of the second interdigital electrode end parts and corresponding parts are obtained, and the widened parts C1 and C2 jointly form widened parts C. The first dummy electrode 212 and the second dummy electrode 222 have a width that is the same as the width of the center region B electrode. In the present specification, the elastic wave propagation direction is referred to as the x-direction. The extending direction of the first interdigital electrode and the second interdigital electrode is set as a first direction y. In the present embodiment, the x-direction is orthogonal to the y-direction, as shown in fig. 2.
As shown in fig. 2, in the IDT electrode, a portion where the first interdigital electrode 211 and the second interdigital electrode 221 overlap in the x direction is an intersection region a. The intersection area a has a central area B, and areas C1 and C2 form a widened portion C. The center region B is located on the center side in the y direction in the intersection region a. C1 and C2 are disposed on both sides of the central area A in the y direction. Overall, the a, C, D and E regions form the total intersection region.
Specifically, as shown in fig. 2, the IDT electrode 2 has a first dummy electrode region, which is close to the bus bar root, and is referred to as a root-side region E1 and a second dummy electrode region E2 (root-side region E2), and further has a first gap region D1 and a second gap region D2. The first gap region D1 is located between the first dummy electrode region E1 and the first widened region C1. The second gap region D2 is located between the second dummy electrode region E2 and the second widened region C2. The sound velocity of the first gap region D1 is higher than that of the center region B and the root side region E1. Similarly, in the second gap region D2, the sound velocity of the second gap region D1 is higher than the sound velocities of the center region B and the second root-side region E2. When the sound velocity in the center region B is set to Vb, the sound velocities in the first and second gap regions D1 and D2 are set to Vd, and the sound velocities in the first and second root side regions E1 and E2 are set to Ve, vd > Vb, vd > Ve. At this time. In the first gap region D1 and the second gap region D2, a high sound velocity region is formed, so that a transverse mode can be effectively suppressed, which is a main object of the present application to provide a dummy electrode and a void region formed between the dummy electrode and the interdigital electrode.
In the present embodiment, the first and second widened portions are provided at both side ends of the first and second interdigital electrodes 211 and 221, so that the mass load of the electrode finger ends increases. At the same time, the end portion is widened on the adjacent finger, and therefore, the sound velocity can be more reliably reduced in the first widened region C1 and the second widened region C2. Setting the sound velocities in the first widened region C1 and the second widened region C2 to Vc can be Vc < Vb, further effectively suppressing the transverse mode.
In this embodiment, the first dummy electrode 212 and the second dummy electrode 222 have a width and a length in a range of: 0.1λ to 1.5λ. The width of the widened electrode is a, the width of the electrode in the central area is b, wherein a=1.1b-1.4b. That is, the width of the dummy electrode is also b, and specifically referring to fig. 2, the length of the widened electrode, that is, the electrode end and the corresponding adjacent side length is 0.1λ to 1λ.
In one embodiment, the support substrate is made of Si material
SiO2 material is selected for low sound velocity film layer
Piezoelectric layer selection material 50Y cut X propagation LiTaO3
In the present embodiment, the wavelength of the IDT electrode: lamIDT electrode metallization ratio: eta, IDT electrode width: wAl =0.5×lam×eta, spacing between two electrodes: space=0.5×lam-wAl
Specifically, as shown in fig. 3 to 4, the behavior of the change in sound velocity was compared by the elastic wave device having the above-described parameter configuration. More specifically, the behavior of the change in sound velocity with respect to the change in the artificial finger and the widening (hammer) is compared.
Fig. 3 is a graph showing the result of simulation comparing the absolute values of admittance curves of a filter with parameter setting and a conventional structure without transverse mode suppression according to the first embodiment of the present application. Fig. 4 is a graph showing the results of comparative simulation of the real part of the admittance curve of the filter according to the first embodiment of the present application and the conventional structure without transverse mode suppression. As shown in fig. 3, the solid line shows the admittance curve of the conventional device without artificial finger and hammer elastic wave, and it can be seen that there is a larger spurious between the resonant frequency and the antiresonant frequency due to the transverse mode, and the real part of the admittance curve is amplified in fig. 4. The absolute value and the real part of the admittance curve of the optimized result of the elastic wave device are shown as the broken lines in fig. 3 and 4, and the transverse mode is obviously inhibited.
The second embodiment is as follows:
the difference between the present embodiment and the first embodiment is that a high sound speed film layer 14 is further disposed between the low sound speed film layer 12 and the support substrate 11, and the high sound speed film layer 14 is made of one of silicon nitride, silicon, aluminum oxide, silicon carbide, sapphire, quartz or diamond.
The specific other structures are consistent with the specific examples, and the parameters of the first embodiment are used for setting the comparison simulation result diagram of the absolute value of the admittance curve of the filter and the admittance curve of the conventional transverse mode suppression structure. The other layers are identical to those of the first embodiment, as shown in fig. 5 in detail, and the top view is identical to the IDT electrode structure (see fig. 2).
Fig. 6 is a graph showing the result of simulation comparing the absolute values of admittance curves of a filter according to the second embodiment of the present application with those of another conventional structure without transverse mode suppression. Fig. 7 is a graph showing the results of comparative simulation of the real part of the admittance curve of a filter according to the second embodiment of the present application and another conventional structure without transverse mode suppression. In fig. 6, the solid line shows the admittance curve of another conventional artificial-free and hammer elastic wave device, and it can be seen that there is a larger spurious between the resonant frequency and the antiresonant frequency due to the transverse mode, and the real part of the admittance curve is amplified in fig. 7. The absolute value and the real part of the admittance curve of the optimizing result of the elastic wave device are shown in the broken lines of fig. 6 and 7, and the transverse mode is obviously inhibited.
Meanwhile, compared with the mode without the high sound speed film layer, the frequency corresponding to the highest point of the peak admittance is also increased by adding the high sound speed film layer, so that the optimization and improvement of the working performance of the resonator and the filter after the high sound speed film layer is added can be further verified.
In addition, the application also discloses a filter containing the implementation mode, and the corresponding filter consists of resonators which are connected in series and in parallel according to the implementation result.
From the foregoing description of the embodiments, it will be appreciated by those skilled in the art that, for convenience and brevity of description, only the above-described division of functional modules is illustrated, and in practical application, the above-described functional allocation may be implemented by different functional modules according to needs, i.e. the internal structure of a specific apparatus is divided into different functional modules to implement all or part of the functions described above.
In the embodiments provided in the present application, it should be understood that the disclosed structures and methods may be implemented in other manners. For example, the embodiments described above with respect to structures are merely illustrative, e.g., the division of modules or units is merely a logical functional division, and there may be additional divisions when actually implemented, e.g., multiple units or components may be combined or integrated into another structure, or some features may be omitted, or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be an indirect coupling or communication connection via interfaces, structures or units, which may be in electrical, mechanical or other forms.
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 application is subject to the protection scope of the claims.
Claims (11)
1. A resonator that suppresses transverse modes, comprising:
a piezoelectric substrate;
an IDT electrode provided on the piezoelectric substrate;
the IDT electrode comprises a first bus bar and a second bus bar, wherein the first bus bar extends to form a first interdigital electrode and a first dummy electrode, and the second bus bar extends to form a second interdigital electrode corresponding to the first dummy electrode and a second dummy electrode corresponding to the first interdigital electrode;
the end part of the first interdigital electrode and the position of the second interdigital electrode adjacent to the end part are provided with widened parts, and the end part of the second interdigital electrode and the position of the first interdigital electrode adjacent to the end part are also provided with widened parts; the first bus bar and the second bus bar are formed with an intersection area, the intersection area comprises a central area and widened areas corresponding to the widened parts, the widened areas are positioned at two sides of the central area, and the sound velocity of the widened areas is lower than that of the central area;
a root-side region of the first dummy electrode corresponding to the second dummy electrode, the root-side region being closer to the bus bar than the widened region, the root-side region having a sound velocity greater than the widened region.
2. The resonator for suppressing a transverse mode according to claim 1, wherein a first gap is provided between the first interdigital electrode and the second dummy electrode, a second gap is also provided between the second interdigital electrode and the first dummy electrode, and a crossing region corresponding to the first gap and the second gap is a gap region, and a sound velocity of the gap region is higher than a sound velocity of the central region.
3. A resonator for suppressing a transverse mode according to claim 1, wherein the first dummy electrode width and the second dummy electrode width are both identical to the central region electrode width.
4. A resonator for suppressing a transverse mode according to any one of claims 1 to 3, wherein the piezoelectric substrate comprises a support substrate, a piezoelectric layer, and a low acoustic velocity film layer provided on a lower surface of the piezoelectric layer, the low acoustic velocity film layer being SiO 2 Film or silicon oxide film or silicon oxynitride film.
5. The resonator for suppressing a transverse mode according to claim 4, wherein the first dummy electrode and the second dummy electrode have a width of 0.1λ -1.5λ.
6. A resonator for suppressing a transverse mode according to claim 4, wherein the width of the widened portion electrode is a and the width of the central region electrode is b, wherein a = 1.1b to 1.4b.
7. A resonator for suppressing a transverse mode according to claim 4, wherein the length of the widened portion electrode is from 0.1λ to 1λ.
8. The resonator for suppressing a transverse mode according to claim 4, wherein the piezoelectric layer is made of 30-60 ° Y cut X propagation LiTaO 3 。
9. The resonator for suppressing a transverse mode as recited in claim 4, wherein said IDT electrode is made of a Ti layer/Al layer from the piezoelectric side.
10. The resonator according to claim 4, wherein a high sound speed film layer is further disposed between the low sound speed film layer and the supporting layer, and the high sound speed film layer is made of one of silicon nitride, silicon, aluminum oxide, silicon carbide, sapphire, quartz or diamond.
11. An elastic wave device, characterized in that: a resonator as claimed in any one of claims 1 to 9.
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| CN116961619A (en) * | 2023-09-21 | 2023-10-27 | 苏州声芯电子科技有限公司 | Surface acoustic wave resonator structure with double transverse mode inhibition |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116961619A (en) * | 2023-09-21 | 2023-10-27 | 苏州声芯电子科技有限公司 | Surface acoustic wave resonator structure with double transverse mode inhibition |
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