CN114629461A - Acoustic surface wave resonator - Google Patents
Acoustic surface wave resonator Download PDFInfo
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- CN114629461A CN114629461A CN202210294578.7A CN202210294578A CN114629461A CN 114629461 A CN114629461 A CN 114629461A CN 202210294578 A CN202210294578 A CN 202210294578A CN 114629461 A CN114629461 A CN 114629461A
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- heterostructure
- acoustic wave
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- 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
- H03H9/02637—Details concerning reflective or coupling arrays
- H03H9/02685—Grating lines having particular arrangements
- H03H9/02724—Comb like grating lines
- H03H9/02732—Bilateral comb like grating lines
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- 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
- H03H9/02543—Characteristics of substrate, e.g. cutting angles
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/46—Filters
- H03H9/64—Filters using surface acoustic waves
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- Acoustics & Sound (AREA)
- Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
Abstract
The embodiment of the invention discloses a surface acoustic wave resonator, which comprises a piezoelectric layer; an electrode layer on the piezoelectric layer; the electrode layer comprises a transducer, and the transducer comprises a first bus bar, a first long finger, a first dummy finger, a second bus bar, a second long finger and a second dummy finger; the first bus bar and the second bus bar extend along a first direction and are arranged oppositely; the first long finger, the second dummy finger, the second long finger and the first dummy finger extend along the second direction and are positioned between the first bus bar and the second bus bar; the first long finger and the second artificial finger are oppositely arranged, the piezoelectric layer comprises at least one heterostructure, the depth of the heterostructure is larger than the thickness of the transducer, the propagation speed of the surface acoustic wave in the heterostructure is different from that in the piezoelectric layer, the heterostructure extends along the first direction, and the heterostructure is overlapped with the vertical projection of the transducer on the piezoelectric layer and is not overlapped with the vertical projections of the first gap and the second gap on the piezoelectric layer. The invention inhibits the transverse mode transmission and improves the performance of the filter.
Description
Technical Field
The embodiment of the invention relates to the technical field of semiconductor packaging, in particular to a surface acoustic wave resonator.
Background
Along with the development of communication technology, a product terminal puts strict requirements on the performance of various devices, and a filter is a key device of a communication system; with the development of the technology, the types of filters are more and more, and the technology of the filters is continuously developed from LCR filters to cavity filters and from LTCC ceramic filters to acoustic surface filters; since the LTE era, the role of surface acoustic filters in communication systems has become increasingly important. Meanwhile, with the development of communication technology, various requirements on the filter are higher and higher; especially with the advent of the fifth Generation mobile communication technology (5th-Generation, 5G), the filter industry faces significant challenges and opportunities.
The acoustic surface filter is widely applied to a radio frequency front end and has the advantages of low insertion loss, wide bandwidth, small size and the like, but acoustic surface resonators have various clutter modes and seriously affect the performance of the acoustic surface filter, and a transverse mode is one of main clutter modes, so that the suppression of the transverse mode has important significance for the performance improvement of the acoustic surface filter.
Disclosure of Invention
The invention provides a surface acoustic wave resonator which can inhibit transmission of a transverse mode so as to improve the performance of a filter.
The embodiment of the invention provides a surface acoustic wave resonator, which comprises:
a piezoelectric layer;
an electrode layer on the piezoelectric layer;
the electrode layer includes a transducer, the transducer including: the first bus bar, the first long finger, the first dummy finger, the second bus bar, the second long finger and the second dummy finger; the first bus bar and the second bus bar extend along a first direction and are oppositely arranged; the first long finger, the second dummy finger, the second long finger and the first dummy finger all extend along a second direction and are located between a first bus bar and a second bus bar; the first long fingers and the first dummy fingers are alternately arranged along a first direction and are connected with the first bus bar; the second long fingers and the second dummy fingers are alternately arranged along a first direction and are connected with the second bus bar; the first long finger and the second artificial finger are oppositely arranged, a first gap is formed between the first long finger and the second artificial finger, the second long finger and the first artificial finger are oppositely arranged, and a second gap is formed between the second long finger and the first artificial finger; wherein the second direction is interdigitated with the first direction;
the piezoelectric layer comprises at least one heterostructure, the depth of the heterostructure is larger than the thickness of the transducer, the propagation speed of a surface acoustic wave in the heterostructure is different from that in the piezoelectric layer, the heterostructure extends along the first direction, the heterostructure overlaps with the transducer in the vertical projection of the piezoelectric layer, and does not overlap with the first gap and the second gap in the vertical projection of the piezoelectric layer.
Optionally, the heterostructure comprises a first hetero-stripe and a second hetero-stripe,
the first heterogeneous long strip is positioned below the first long finger, and the side surface of the first heterogeneous long strip, which is adjacent to the first gap, is flush with the top end, which is far away from the first bus bar, of the first long finger;
the heterogeneous rectangular of second is located the long below of finger of second, just the heterogeneous rectangular side that is close to the second clearance with the long finger of second is kept away from the top parallel and level of second busbar.
Optionally, the heterostructure includes a third hetero-stripe and a fourth hetero-stripe,
the third heterogeneous strip is positioned below the second bus bar, and the side face of the third heterogeneous strip adjacent to the second fake finger is flush with the end, adjacent to the second bus bar, of the second fake finger;
the fourth heterogeneous strip is located below the first bus bar, and the side face of the fourth heterogeneous strip, which is adjacent to the first artificial finger, is flush with the end of the first artificial finger, which is adjacent to the first bus bar.
Optionally, a surface of the piezoelectric layer adjacent to the electrode layer is provided with a cavity structure, and the heterostructure includes the cavity structure.
Optionally, a groove is formed in the surface, adjacent to the electrode layer, of the piezoelectric layer, a heterogeneous material layer is filled in the groove, and the heterogeneous structure includes the heterogeneous material layer.
Optionally, the material adopted by the heterogeneous material layer includes silicon dioxide or silicon nitride.
Optionally, a doping region is disposed on a surface of the piezoelectric layer adjacent to the electrode layer, and the heterostructure includes the piezoelectric layer doped with the set particles in the doping region.
Optionally, the set particles comprise vanadium or the set particles comprise hydrogen and helium.
Optionally, a width W of the heterostructure in the second direction and a difference Δ V in acoustic velocity between the acoustic velocity of the surface acoustic wave resonator and the acoustic velocity of the heterostructure satisfy the following relationship: w is K Δ V λ/V, wherein λ is the wavelength of the surface acoustic wave, V is the sound velocity of the piezoelectric layer material, K is the adjustment coefficient, and the value range of K is 0.8-1.2;
the depth of the heterostructure along the thickness direction of the surface acoustic wave resonator comprises 0.3 lambda-3 lambda, wherein lambda is the wavelength of the surface acoustic wave, and the length of the heterostructure along the first direction is larger than that of the surface acoustic wave resonator.
Optionally, the surface acoustic wave resonator further includes a temperature compensation layer located on a side of the electrode layer away from the piezoelectric layer, and a substrate located on a side of the piezoelectric layer away from the electrode layer.
In the embodiment, the heterostructure is arranged in the piezoelectric layer, the heterostructure has different sound velocity from that of the piezoelectric layer, and sound velocity abrupt change exists in the transverse direction of the resonator, so that the surface acoustic wave is limited in the resonator, and meanwhile, the depth of the heterostructure is greater than the thickness of the transducer, so that a transverse mode can be inhibited, the Q value of the resonator is improved, and the transverse crosstalk of adjacent resonators is prevented; the problem of surface acoustic wave resonator and the filter of traditional design have very strong transverse mode in use, lead to whole device performance to worsen is solved, and the technical scheme of this embodiment can make transverse mode obtain effectual suppression to promote the performance of filter.
Drawings
Fig. 1 is a schematic structural diagram of a surface acoustic wave resonator according to an embodiment of the present invention;
fig. 2 is a schematic partial plan view of a surface acoustic wave resonator according to an embodiment of the present invention;
FIG. 3 is a schematic diagram illustrating a distribution of wave velocities of a surface wave of a conventional resonator according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a distribution of a wave velocity of a surface wave of a high acoustic velocity heterostructure resonator according to an embodiment of the present invention;
fig. 5 is a schematic diagram illustrating a distribution of wave velocities of a surface wave of a low-velocity heterostructure resonator provided by an embodiment of the present invention;
fig. 6 is a cross-sectional view of a saw resonator corresponding to fig. 2 along section line AA, in accordance with an embodiment of the present invention;
fig. 7 is a partial plan view of yet another saw resonator provided by an embodiment of the present invention;
fig. 8 is a cross-sectional view of a surface acoustic wave resonator corresponding to fig. 7 taken along section line BB in accordance with an embodiment of the present invention;
fig. 9 is a partial plan view of yet another saw resonator provided by an embodiment of the present invention;
fig. 10 is a schematic structural diagram of another surface acoustic wave resonator according to an embodiment of the present invention;
fig. 11 is a cross-sectional view, taken along section line AA, of a saw resonator having a temperature compensation layer, corresponding to that of fig. 2, in accordance with an embodiment of the present invention;
fig. 12 is a cross-sectional view of a surface acoustic wave resonator having a temperature compensation layer corresponding to fig. 7, taken along section line BB, in accordance with an embodiment of the present invention;
fig. 13 is a cross-sectional view, taken along section line AA, of a saw resonator having a substrate, according to an embodiment of the present invention, shown in fig. 2;
fig. 14 is a cross-sectional view, taken along section line AA, of yet another saw resonator having a substrate, according to an embodiment of the present invention, shown in fig. 2;
fig. 15 is a cross-sectional view of a saw resonator having a substrate corresponding to fig. 7 taken along section line BB in accordance with an embodiment of the present invention;
fig. 16 is a cross-sectional view of still another saw resonator having a substrate, corresponding to fig. 7, taken along section line BB, according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
Fig. 1 is a schematic structural diagram of a surface acoustic wave resonator according to an embodiment of the present invention, fig. 2 is a schematic partial plan view of a surface acoustic wave resonator according to an embodiment of the present invention, and referring to fig. 1 and fig. 2, an embodiment of the present invention provides a surface acoustic wave resonator for suppressing a transverse mode, the surface acoustic wave resonator including: a piezoelectric layer 120; an electrode layer 130 on the piezoelectric layer 120; the electrode layer 130 includes a transducer 131, the transducer 131 including: a first bus bar 10, a first long finger 11, a first dummy finger 12, a second bus bar 20, a second long finger 21, and a second dummy finger 22; the first bus bar 10 and the second bus bar 20 both extend in the first direction 1 and are oppositely arranged; the first long finger 11, the second dummy finger 22, the second long finger 21 and the first dummy finger 12 all extend in the second direction 2 and are located between the first bus bar 10 and the second bus bar 20; the first long fingers 11 and the first dummy fingers 12 are alternately arranged along the first direction 1 and are connected with the first bus bar 10; the second long fingers 21 and the second dummy fingers 22 are alternately arranged along the first direction 1 and are connected to the second bus bar 20; the first long finger 11 and the second artificial finger 22 are oppositely arranged, a first gap 1122 is formed between the first long finger 11 and the second artificial finger 22, the second long finger 21 and the first artificial finger 12 are oppositely arranged, and a second gap 2112 is formed between the second long finger 21 and the first artificial finger 12; wherein the second direction 2 is mutually crossed with the first direction 1; piezoelectric layer 120 includes at least one heterostructure 121 having a depth greater than the thickness of the transducer, a surface acoustic wave propagating in heterostructure 121 at a velocity different from that of piezoelectric layer 120, heterostructure 121 extending along first direction 1, heterostructure 121 overlapping with a perpendicular projection of transducer 131 on piezoelectric layer 120 and not overlapping with a perpendicular projection of first gap 1122 and second gap 2112 on piezoelectric layer 120.
Specifically, the material of the piezoelectric layer 120 may be lithium niobate or lithium cobaltate, and the electrode layer 130 is formed by depositing a metal film on the surface of the piezoelectric layer 120 by means of electron beam evaporation, plasma, magnetron sputtering, or the like. Among them, the material of the deposited metal film may be titanium, chromium, copper, silver, aluminum, etc., or a combination thereof. The number of the first long finger 11, the second artificial finger 22, the second long finger 21 and the first artificial finger 12 is equal. The first bus bar 10 and the second bus bar 20 are always parallel to the first direction 1, and the included angle at which the second direction 2 and the first direction 1 intersect with each other may be set as required, and the embodiment of the present invention exemplarily illustrates a case where the included angle is 90 °.
The number of the transducers 131 in the electrode layer 130 can be multiple, and the number of the heterostructures 121 in the piezoelectric layer 120 can be one or more, and the specific number can be set according to actual needs. Each transducer 131 corresponds to at least one heterostructure 121, the heterostructure 121 cannot be located under the first gap 1122 and the second gap 2112, and the heterostructure 121 can be located at any position under the first bus bar 10, the first long finger 11, the first dummy finger 12, the second bus bar 20, the second long finger 21 and the second dummy finger 22.
The heterostructure can be a high acoustic velocity heterostructure, which refers to an acoustic velocity of the heterostructure higher than that of the piezoelectric layer, or a low acoustic velocity heterostructure, which refers to an acoustic velocity of the heterostructure lower than that of the piezoelectric layer. Fig. 3 is a schematic diagram of the wave velocity distribution of a conventional resonator surface wave provided by an embodiment of the present invention, fig. 4 is a schematic diagram of the wave velocity distribution of a high-sound-velocity heterostructure resonator surface wave provided by an embodiment of the present invention, fig. 5 is a schematic diagram of the wave velocity distribution of a low-sound-velocity heterostructure resonator surface wave provided by an embodiment of the present invention, and referring to fig. 3-5, it can be seen from fig. 4 that the middle region between two high-sound-velocity heterostructures is greatly changed from the wave velocity of the heterostructure region; it can be seen from fig. 5 that the middle region where the two low acoustic velocity heterostructures are separated has a large variation in wave velocity compared to the heterostructure region. In summary, the heterostructure can limit the transmission of the transverse mode, and can limit the surface acoustic wave in the resonator, thereby improving the performance of the resonator.
In the embodiment, the heterostructure is arranged in the piezoelectric layer, the heterostructure has different sound velocity from that of the piezoelectric layer, and sound velocity abrupt change exists in the transverse direction of the resonator, so that the surface acoustic wave is limited in the resonator, and meanwhile, the depth of the heterostructure is greater than the thickness of the transducer, so that a transverse mode can be inhibited, the Q value of the resonator is improved, and the transverse crosstalk of adjacent resonators is prevented; the problem of surface acoustic wave resonator and the filter of traditional design have very strong transverse mode in use, lead to whole device performance to worsen is solved, and the technical scheme of this embodiment can make transverse mode obtain effectual suppression to promote the performance of filter.
With continued reference to fig. 2, optionally, the heterostructure 121 includes a first hetero-stripe 1211 and a second hetero-stripe 1212, the first hetero-stripe 1211 is located below the first long finger 11, and a side of the first hetero-stripe 1211 adjacent to the first gap 1122 is flush with a top end of the first long finger 11 away from the first bus bar 10;
the second hetero-bar 1212 is located below the second long finger 21, and the side of the second hetero-bar 1212 adjacent to the 2112 of the second gap is flush with the top end of the second long finger 21 away from the second bus bar 20.
Fig. 6 is a cross-sectional view of the surface acoustic wave resonator corresponding to fig. 2 taken along a section line AA according to the embodiment of the present invention, and referring to fig. 6, the position information of the first hetero-strip 1211 and the second hetero-strip 1212, the depth and width of the first hetero-strip 1211 and the second hetero-strip 1212, and the like are clarified.
Fig. 7 is a partial plan view of yet another saw resonator provided by an embodiment of the invention, and referring to fig. 7, alternatively, the heterostructure 121 includes a third heterostructure 1213 and a fourth heterostructure 1214,
the third qualitative strip 1213 is located below the second bus bar 20, and the side of the third qualitative strip 1213 adjacent to the second artificial finger 22 is flush with the end of the second artificial finger 22 adjacent to the second bus bar 20;
the fourth heterogeneous strip 1214 is located below the first bus bar 10, and the side of the fourth heterogeneous strip 1214 adjacent to the first artificial finger 12 is flush with the end of the first artificial finger 12 adjacent to the first bus bar 10.
Fig. 8 is a cross-sectional view of the surface acoustic wave resonator corresponding to fig. 7 along a section line BB according to the embodiment of the present invention, and referring to fig. 8, positional information of the third hetero-strip 1213 and the fourth hetero-strip 1214, depths and widths of the third hetero-strip 1213 and the fourth hetero-strip 1214, and the like are clarified.
The first hetero-strip 1211, the second hetero-strip 1212, the third hetero-strip 1213 and the fourth hetero-strip 1214 in the heterostructure 121 have different sound velocities from the piezoelectric layer, and the sound velocity abrupt change exists in the transverse direction of the resonator, so that the surface acoustic wave can be limited in the resonator, the transverse mode can be effectively suppressed, and the performance of the filter can be improved.
The first hetero stripe 1211 is disposed below the first long finger 11 and the second hetero stripe 1212 is disposed below the second long finger 21, so that abrupt change of the sound velocity in the transverse direction is intensified, and the surface acoustic wave can be better confined in the resonator. Disposing the third hetero-stripe 1213 below the second bus bar 20 and the fourth hetero-stripe 1214 below the first bus bar 10 can reduce process difficulty while preventing lateral crosstalk of adjacent resonators.
Fig. 9 is a partial plan view schematically illustrating still another surface acoustic wave resonator according to an embodiment of the present invention, and referring to fig. 9, fig. 9 shows a case where the heterostructure 121 includes a first hetero-strip 1211, a second hetero-strip 1212, a third hetero-strip 1213, and a fourth hetero-strip 1214.
The electrode layer 130 further includes a first reflective grating structure 132 and a second reflective grating structure 133, the first reflective grating structure 132 and the second reflective grating structure 133 are respectively disposed at two sides of the transducer 131; the first and second reflective grill structures 132 and 133 each include a third bus bar 30, a fourth bus bar 40, and a plurality of reflective grills 50; the third and fourth bus bars 30 and 40 extend in the first direction 1; a first end of the reflection fence 50 is connected to the third bus bar 30, and a second end of the reflection fence 50 is connected to the fourth bus bar 40.
Wherein, the number of the reflective gratings in the first reflective grating structure 132 and the second reflective grating structure 133 may be 5. The first reflective grating structure 132 and the second reflective grating structure 133 can reflect the energy of the surface acoustic wave, concentrating the energy in the transducer 131. The embodiment of the invention arranges a plurality of reflecting grids 50 to be parallel to the first long finger 11, the second artificial finger 22, the second long finger 21 and the first artificial finger 12, and further ensures that the reflecting grids 50 in the first reflecting grid structure 132 and the second reflecting grid structure 133 concentrate the reflected surface acoustic wave energy into the transducer, thereby improving the Q value of the surface acoustic wave resonator.
Optionally, a surface of the piezoelectric layer adjacent to the electrode layer is provided with a cavity structure, and the heterostructure comprises a cavity structure.
Specifically, the cavity structure may be filled with air. The specific manufacturing process of the cavity structure can be as follows: and etching corresponding grooves on the piezoelectric layer at positions corresponding to the heterostructure by adopting an etching process, filling sacrificial materials in the grooves, and corroding and removing the sacrificial materials after the transducer is completed.
Optionally, a groove is formed in the surface, adjacent to the electrode layer, of the piezoelectric layer, the groove is filled with the heterogeneous material layer, and the heterogeneous structure includes the heterogeneous material layer.
Specifically, corresponding grooves are etched in the positions of the corresponding heterogeneous structures on the piezoelectric layer, the heterogeneous material layers are made of different materials from the piezoelectric layer, therefore, the sound velocity of the heterogeneous material layers is different from that of the piezoelectric layer, and sound velocity abrupt changes exist between the heterogeneous material layers and the piezoelectric layer in the transverse direction of the resonator, so that the surface acoustic waves are limited in the resonator.
Optionally, the material used for the heterogeneous material layer includes silicon dioxide or silicon nitride.
Specifically, silicon dioxide or silicon nitride is formed in the groove through plasma vapor deposition and other processes after etching, flatness restoration is performed through etching or chemical mechanical polishing, then deposition etching and other processes of the transducer are performed, and the subsequent processes are the same as those of a conventional surface acoustic wave resonator.
Optionally, the surface of the piezoelectric layer adjacent to the electrode layer is provided with a doped region, and the heterostructure includes the piezoelectric layer doped with the doped region after the set particles are doped.
Specifically, set ion doping needs to be performed on the corresponding position of the piezoelectric layer according to the position and the structure of the resonator, and the set ions are injected into the doped region of the piezoelectric layer, which is adjacent to the surface of the electrode layer, at a high speed by adopting an ion injection process.
Optionally, the set particles comprise vanadium or the set particles comprise hydrogen and helium.
Specifically, vanadium particles may be doped to form a high acoustic velocity layer, and hydrogen particles and helium particles may be doped to form a low acoustic velocity layer. When vanadium and the like are adopted as doping particles, the sound velocity of the heterostructure can be obviously higher than that of the piezoelectric layer, so that the sound velocity abrupt change exists in the transverse direction, and the surface acoustic wave is limited in the resonator. And because the depth of the heterostructure is larger than the thickness of the transducer, the heterostructure can restrain transverse bulk waves, thereby improving the Q value of the resonator and preventing the transverse crosstalk of the adjacent resonator.
The low-acoustic-velocity layer, namely the defect layer, can be formed by adopting hydrogen, helium and the like as doping particles, the acoustic velocity of the heterostructure can be reduced compared with that of the piezoelectric layer, and the acoustic velocity of the heterostructure can also have abrupt change in the transverse direction, so that the surface acoustic wave is limited in the resonator. And because the depth of the heterostructure is larger than the thickness of the transducer, the heterostructure can restrain transverse bulk waves, thereby improving the Q value of the resonator and preventing the transverse crosstalk of the adjacent resonator.
Alternatively, the width W of the heterostructure in the second direction and the difference Δ V in acoustic velocity between the acoustic velocity of the surface acoustic wave resonator and the acoustic velocity of the heterostructure satisfy the following relationship: w is K Δ V λ/V, wherein λ is the wavelength of the surface acoustic wave, V is the sound velocity of the piezoelectric layer material, K is the adjustment coefficient, and the value range of K is 0.8-1.2;
the depth of the heterostructure along the thickness direction of the surface acoustic wave resonator comprises 0.3 lambda-3 lambda, wherein lambda is the wavelength of the surface acoustic wave, and the length of the heterostructure along the first direction is larger than the length of the surface acoustic wave resonator.
Specifically, the width of the heterostructure in the second direction and the depth in the thickness direction of the surface acoustic wave resonator are closely related to the material of the piezoelectric layer, the resonator structure, and the acoustic velocity of the heterostructure. The width W of the heterostructure in the second direction is proportional to the sound velocity difference Δ V between the sound velocity V1 of the surface acoustic wave resonator and the sound velocity V2 of the heterostructure, and specifically, the calculation formula is as follows: w ═ K ×, Δ V ×, λ/V, (V1-V2), where K ranges from 0.8 to 1.2.
The depth of the heterostructure in the thickness direction of the surface acoustic wave resonator needs to consider the performance requirements of the resonator, for example, the depth of the heterostructure can be changed from 0.3 lambda to 3 lambda, so that the process difficulty can be reduced, the depth is flexible and adjustable, the surface acoustic wave can be limited in the resonator, and a transverse mode can be effectively inhibited.
Fig. 10 is a schematic structural diagram of another surface acoustic wave resonator provided in an embodiment of the present invention, and referring to fig. 10, optionally, the surface acoustic wave resonator further includes a temperature compensation layer 140 and a substrate 110, the temperature compensation layer 140 is located on a side of the electrode layer 130 away from the piezoelectric layer 120, and the substrate 110 is located on a side of the piezoelectric layer 120 away from the electrode layer 130.
Specifically, the substrate 110 may be made of high-resistance silicon, and the substrate 110 may also be a composite multilayer substrate, so that the surface acoustic wave resonator can realize characteristics such as low insertion loss, smooth passband, high Q value, and excellent low-frequency temperature. The material of the temperature compensation layer 140 may be silicon dioxide or silicon nitride.
Fig. 11 is a cross-sectional view of a surface acoustic wave resonator having a temperature compensation layer corresponding to fig. 2 along a section line AA according to an embodiment of the present invention, fig. 12 is a cross-sectional view of a surface acoustic wave resonator having a temperature compensation layer corresponding to fig. 7 along a section line BB according to an embodiment of the present invention, and referring to fig. 11 and 12, the temperature compensation layer 140 can prevent a temperature change from affecting a resonant frequency of the surface acoustic wave resonator.
Fig. 13 is a sectional view of a surface acoustic wave resonator with a substrate corresponding to fig. 2 along a sectional line AA according to an embodiment of the present invention, fig. 14 is a sectional view of a surface acoustic wave resonator with a substrate corresponding to fig. 2 along a sectional line AA according to another embodiment of the present invention, and fig. 13 and 14 show different depth heterostructures, respectively.
Fig. 15 is a sectional view of a surface acoustic wave resonator having a substrate provided by an embodiment of the present invention and corresponding to fig. 7 taken along a section line BB, fig. 16 is a sectional view of a surface acoustic wave resonator having a substrate provided by an embodiment of the present invention and corresponding to fig. 7 taken along a section line BB, and fig. 15 and 16 show the case of different-depth heterostructures, respectively, with reference to fig. 15 and 16.
An embodiment of the present invention also provides a filter including at least two surface acoustic wave resonators according to any one of the above embodiments.
The filter may be formed by connecting two or more surface acoustic wave resonators in series and/or in parallel in the above embodiments.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.
Claims (10)
1. A surface acoustic wave resonator, comprising:
a piezoelectric layer;
an electrode layer on the piezoelectric layer;
the electrode layer includes a transducer, the transducer including: the first bus bar, the first long finger, the first dummy finger, the second bus bar, the second long finger and the second dummy finger; the first bus bar and the second bus bar extend along a first direction and are oppositely arranged; the first long finger, the second dummy finger, the second long finger and the first dummy finger all extend along a second direction and are located between a first bus bar and a second bus bar; the first long fingers and the first dummy fingers are alternately arranged along a first direction and are connected with the first bus bar; the second long fingers and the second dummy fingers are alternately arranged along a first direction and are connected with the second bus bar; the first long finger and the second artificial finger are oppositely arranged, a first gap is formed between the first long finger and the second artificial finger, the second long finger and the first artificial finger are oppositely arranged, and a second gap is formed between the second long finger and the first artificial finger; wherein the second direction is interdigitated with the first direction;
the piezoelectric layer comprises at least one heterostructure, the depth of the heterostructure is larger than the thickness of the transducer, the propagation speed of a surface acoustic wave in the heterostructure is different from that in the piezoelectric layer, the heterostructure extends along the first direction, the heterostructure overlaps with the transducer in the vertical projection of the piezoelectric layer, and does not overlap with the first gap and the second gap in the vertical projection of the piezoelectric layer.
2. A surface acoustic wave resonator according to claim 1, wherein said hetero-structure includes a first hetero-strip and a second hetero-strip,
the first heterogeneous long strip is positioned below the first long finger, and the side surface of the first heterogeneous long strip, which is adjacent to the first gap, is flush with the top end, which is far away from the first bus bar, of the first long finger;
the heterogeneous rectangular of second is located the long below of finger of second, just the heterogeneous rectangular side that is close to the second clearance with the long finger of second is kept away from the top parallel and level of second busbar.
3. A surface acoustic wave resonator according to claim 1 or 2, characterized in that the heterostructure includes a third hetero-strip and a fourth hetero-strip,
the third heterogeneous strip is positioned below the second bus bar, and the side surface of the third heterogeneous strip, which is adjacent to the second artificial finger, is flush with the tail end of the second artificial finger, which is adjacent to the second bus bar;
the fourth hetero-strip is located below the first bus bar, and a side of the fourth hetero-strip adjacent to the first artificial finger is flush with an end of the first artificial finger adjacent to the first bus bar.
4. A surface acoustic wave resonator according to claim 1, wherein a surface of said piezoelectric layer adjacent to said electrode layer is provided with a cavity structure, and said heterostructure includes said cavity structure.
5. A surface acoustic wave resonator according to claim 1, wherein a surface of said piezoelectric layer adjacent to said electrode layer is provided with a groove filled with a hetero material layer, and said hetero structure includes said hetero material layer.
6. A surface acoustic wave resonator according to claim 5, wherein said hetero material layer is made of a material including silicon dioxide or silicon nitride.
7. A surface acoustic wave resonator according to claim 1, characterized in that the surface of the piezoelectric layer adjacent to the electrode layer is provided with a doped region, and the heterostructure comprises the piezoelectric layer doped with the doped region with set particles.
8. A surface acoustic wave resonator according to claim 7, wherein said setting particles include vanadium or said setting particles include hydrogen and helium.
9. The surface acoustic wave resonator according to claim 1, wherein a width W of the heterostructure in the second direction and an acoustic velocity difference av of an acoustic velocity of the surface acoustic wave resonator and an acoustic velocity of the heterostructure satisfy a relationship: w is K is Δ V is λ/V, wherein λ is the wavelength of the surface acoustic wave, V is the sound velocity of the piezoelectric layer material, K is the adjustment coefficient, and the value range of K is 0.8-1.2;
the depth of the heterostructure along the thickness direction of the surface acoustic wave resonator comprises 0.3 lambda-3 lambda, wherein lambda is the wavelength of the surface acoustic wave, and the length of the heterostructure along the first direction is larger than that of the surface acoustic wave resonator.
10. The surface acoustic wave resonator according to claim 1, further comprising a temperature compensation layer on a side of said electrode layer remote from said piezoelectric layer, and a substrate on a side of said piezoelectric layer remote from said electrode layer.
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| CN116938189A (en) * | 2023-09-15 | 2023-10-24 | 锐石创芯(深圳)科技股份有限公司 | Resonator, filter, multiplexer and radio frequency front end module |
| CN116938189B (en) * | 2023-09-15 | 2023-12-22 | 锐石创芯(深圳)科技股份有限公司 | Resonator, filter, multiplexer and radio frequency front end module |
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