CN111884619A - Resonator having a dielectric layer - Google Patents
Resonator having a dielectric layer Download PDFInfo
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- CN111884619A CN111884619A CN202010664307.7A CN202010664307A CN111884619A CN 111884619 A CN111884619 A CN 111884619A CN 202010664307 A CN202010664307 A CN 202010664307A CN 111884619 A CN111884619 A CN 111884619A
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- 239000002131 composite material Substances 0.000 claims abstract description 48
- 239000000758 substrate Substances 0.000 claims abstract description 45
- 230000005284 excitation Effects 0.000 claims description 30
- 239000012528 membrane Substances 0.000 abstract description 5
- 230000000694 effects Effects 0.000 description 10
- 239000000463 material Substances 0.000 description 7
- 238000000034 method Methods 0.000 description 3
- 238000005452 bending Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000003071 parasitic effect Effects 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 230000000644 propagated effect Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
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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
- H03H9/15—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
- H03H9/171—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator implemented with thin-film techniques, i.e. of the film bulk acoustic resonator [FBAR] type
- H03H9/172—Means for mounting on a substrate, i.e. means constituting the material interface confining the waves to a volume
- H03H9/174—Membranes
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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
- H03H9/15—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
- H03H9/171—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator implemented with thin-film techniques, i.e. of the film bulk acoustic resonator [FBAR] type
- H03H9/172—Means for mounting on a substrate, i.e. means constituting the material interface confining the waves to a volume
- H03H9/175—Acoustic mirrors
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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
- H03H9/15—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
- H03H9/178—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator of a laminated structure of multiple piezoelectric layers with inner electrodes
Abstract
The invention provides a resonator, which comprises a substrate, a composite film arranged on the substrate along a first direction and a longitudinal sound wave reflector arranged on one side of the composite film close to the substrate; the composite membrane comprises a first electrode, a piezoelectric functional membrane and a second electrode which are sequentially arranged along a first direction, wherein the first electrode is arranged on the substrate and the longitudinal sound wave reflector; the area surrounded by the orthographic projection of the inner side surface of the transverse sound wave reflector to the composite film along the first direction is a resonance area, and the area of the resonator outside the resonance area is a non-resonance area; the first electrode, the piezoelectric functional film and the second electrode completely cover the resonance area; the acoustic impedance of the part of the composite film located in the resonance area is different from that of the part of the composite film located in the non-resonance area, and the acoustic impedances of the parts of the first electrode, the piezoelectric functional film and the second electrode located in the resonance area are all approximately unchanged. Compared with the related art, the resonator of the invention has small energy loss and increased Q value.
Description
[ technical field ] A method for producing a semiconductor device
The invention relates to the technical field of resonators, in particular to a film bulk acoustic resonator.
[ background of the invention ]
With the increasing of intelligent devices and the constant popularization of the internet of things and 5G technologies, the demand for high-performance filters and multi-functional devices is increasing. Acoustic resonators, which are important components of filters and multiplexers, have been the subject of considerable research in recent years.
In the related art, a resonator includes a substrate, a first electrode, a piezoelectric film, and a second electrode arranged in a first direction, and a longitudinal acoustic wave reflector is arranged between the substrate and the first electrode; the area surrounded by the inner edge of the longitudinal sound wave reflector along the orthographic projection of the first direction is a resonance area, the area surrounded by the overlapping part of the first electrode, the second electrode and the piezoelectric film along the first direction is an excitation area, and longitudinal sound waves and transverse sound waves can be generated in the excitation area.
However, in the related art, the composite film is discontinuous outside the excitation region and the excitation region, and when the transverse sound wave propagates outwards to the side of the excitation region and the side of the resonance region, a primary sound wave scattering effect occurs respectively, which results in superimposed vibration of a large amount of transverse waves, and a large amount of sound wave energy enters the substrate to be dissipated, resulting in a large reduction in the Q value of the anti-resonance point.
Therefore, there is a need to provide a new resonator to solve the above technical problems.
[ summary of the invention ]
The invention aims to provide a resonator which reduces energy loss and increases a Q value.
In order to achieve the above object, the present invention provides a resonator, which includes a substrate, a composite film disposed over the substrate along a first direction, and a longitudinal acoustic wave reflector disposed on a side of the composite film close to the substrate; the composite film comprises a first electrode, a piezoelectric functional film and a second electrode which are sequentially arranged along the first direction, wherein the first electrode is arranged on the substrate and the longitudinal sound wave reflector; the resonator also comprises a closed or opened annular transverse sound wave reflector arranged on the surface of the composite film, the area surrounded by the orthographic projection of the inner side surface of the transverse sound wave reflector to the composite film along the first direction is a resonance area, and the area of the resonator outside the resonance area is a non-resonance area; the first electrode, the piezoelectric functional film and the second electrode all completely cover the resonance region; the piezoelectric functional film comprises a longitudinal piezoelectric film which is positioned in the resonance area and arranged on one side of the first electrode away from the substrate, and a longitudinal non-piezoelectric film which surrounds the outer periphery of the longitudinal piezoelectric film and is arranged on one side of the first electrode away from the substrate; the acoustic impedance of the portion of the resonator located in the resonance region is different from the acoustic impedance of the portion of the resonator located in the non-resonance region, and the acoustic impedances of the first electrode, the piezoelectric functional film, and the portion of the second electrode located in the resonance region are all substantially constant.
Preferably, the longitudinal acoustic wave reflector is disposed around the lateral acoustic wave reflector, and the lateral acoustic wave reflector is disposed on a side of the first electrode away from the second electrode.
Preferably, the substrate includes a bottom wall opposite to and spaced from the first electrode, and an annular side wall extending from the bottom wall to the first electrode in a bending manner, the first electrode is disposed on a side of the side wall away from the bottom wall, and the side wall serves as the transverse acoustic wave reflector.
Preferably, the side wall and the bottom wall jointly enclose a cavity structure, the cavity structure serves as the longitudinal acoustic wave reflector, and the first electrode completely covers the cavity structure.
Preferably, the transverse acoustic wave reflector is disposed on a side of the piezoelectric functional film away from the first electrode and at least partially surrounds the second electrode, an inner side surface of the transverse acoustic wave reflector abuts against the second electrode, and an acoustic impedance of the transverse acoustic wave reflector is different from an acoustic impedance of the second electrode.
Preferably, the acoustic impedance of the transverse acoustic wave reflector is greater than the acoustic impedance of the second electrode.
Preferably, the substrate includes a bottom wall opposite to and spaced from the first electrode, and a side wall bent and extended from the bottom wall to the first electrode to form a ring shape, the side wall and the bottom wall together enclose a cavity structure, the cavity structure serves as the longitudinal acoustic wave reflector, and the first electrode is disposed on a side of the side wall away from the bottom wall.
Preferably, the longitudinal acoustic wave reflector is a bragg acoustic mirror disposed on a side of the substrate close to the first electrode, and the first electrode is disposed on a side of the bragg acoustic mirror away from the substrate.
Preferably, a forward projection of a region surrounded by inner side surfaces of the transverse acoustic wave reflector to the longitudinal acoustic wave reflector along the first direction at least partially falls within a range of the longitudinal acoustic wave reflector.
Preferably, an orthographic projection of the longitudinal piezoelectric film to the transverse acoustic wave reflector along the first direction completely falls within an area surrounded by inner side faces of the transverse acoustic wave reflector.
Preferably, a portion of the composite film, which falls on a region surrounded by outer sides of the longitudinal piezoelectric films along the first direction, forms an excitation region, and the excitation region is located in the resonance region.
Preferably, the longitudinal piezoelectric film has a piezoelectric coefficient along the first direction, and the piezoelectric coefficient of the longitudinal non-piezoelectric film along the first direction is zero or smaller than the piezoelectric coefficient of the longitudinal piezoelectric film along the first direction.
Compared with the prior art, in the resonator, the closed or opened annular transverse sound wave reflector is arranged on the surface of the composite film, the area surrounded by the orthographic projection of the inner side surface of the transverse sound wave reflector to the composite film along the first direction is a resonance area, and the area of the resonator outside the resonance area is a non-resonance area; the first electrode, the piezoelectric functional film and the second electrode completely cover the resonance area; the piezoelectric functional film comprises a longitudinal piezoelectric film which is positioned in the resonance area and arranged on one side of the first electrode, which is far away from the substrate, and a longitudinal non-piezoelectric film which surrounds the outer periphery of the longitudinal piezoelectric film and is arranged on one side of the first electrode, which is far away from the substrate; the acoustic impedance of the part of the resonator, which is positioned in the resonance area, is different from the acoustic impedance of the part of the resonator, which is positioned in the non-resonance area, and the acoustic impedances of the parts of the first electrode, the piezoelectric functional film and the second electrode, which are positioned in the resonance area, are all approximately unchanged; in the structure, the acoustic impedance of the part of the resonator in the resonance area and the acoustic impedance of the part of the resonator in the non-resonance area are discontinuous through the arrangement of the transverse sound wave reflector, the inner side surface of the transverse sound wave reflector serves as an interface of the resonance area and the non-resonance area, the acoustic impedances of the composite film on two sides of the inner side surface of the transverse sound wave reflector are discontinuous, in the outward propagation process of transverse sound waves, a sound wave scattering effect only occurs on the inner side surface of the transverse sound wave reflector, and the transverse sound wave reflector mainly has a sound wave reflection effect on the transverse sound waves, so that under the combined action of the longitudinal sound wave reflector and the transverse sound wave reflector, transverse wave resonance is less and weaker, and the Q value of an anti-resonance point is.
[ description of the drawings ]
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without inventive efforts, wherein:
fig. 1 is a schematic perspective view of a resonator according to a first embodiment of the present invention;
FIG. 2 is an exploded view of a portion of a first embodiment of a resonator according to the present invention;
FIG. 3 is a cross-sectional view taken along line A-A of FIG. 1;
FIG. 4 is a graph of the impedance of the resonator of the present invention compared to a related art resonator;
fig. 5 is a schematic perspective view of a resonator according to a second embodiment of the present invention;
FIG. 6 is an exploded view of a partial perspective structure of a second resonator embodiment of the present invention;
fig. 7 is a cross-sectional view taken along line B-B of fig. 5.
[ detailed description ] embodiments
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
First, it should be noted that in practical applications, the shape of the electrodes in the resonator is mostly an apodized polygon, and the specific shape of the electrodes in the resonator can be specifically set according to the practical design, for example, the shapes of the resonator electrodes of the first embodiment shown in fig. 1 to 3 and the resonator electrodes of the second embodiment shown in fig. 5 to 7 mentioned below are both squares, and the setting of the shapes is not limited to the shape of the resonator electrodes in this patent and can not be apodized polygons and other shapes. The resonator of the invention is described in the following by two embodiments:
implementation mode one
Referring to fig. 1 to 3, the present invention provides a resonator 100, which includes a substrate 1, a composite film 2 disposed above the substrate 1 along a first direction (i.e., an X-axis direction), a longitudinal acoustic wave reflector 3 disposed on a side of the composite film 2 close to the substrate 1, and a transverse acoustic wave reflector 4 disposed on a surface of the composite film 2, wherein the first direction is a thickness direction of the resonator 100.
The composite film 2 comprises a first electrode 21, a piezoelectric functional film 22 and a second electrode 23 which are sequentially arranged along the first direction, wherein the first electrode 21 is arranged on the substrate 1 and the longitudinal acoustic wave reflector 3. The arrangement mode of the two adjacent structures is not limited, and the two adjacent structures may be directly contacted with each other or indirectly connected through another structure arranged between the adjacent structures, in the first embodiment, the composite film 2 is stacked on the surface of the substrate 1, the first electrode 21 is stacked on the substrate 1 and covers the longitudinal acoustic wave reflector 3, the piezoelectric functional film 22 is stacked on the surface of the first electrode 21, and the second electrode 23 is stacked on the surface of the piezoelectric functional film 22 away from the first electrode 21; in other embodiments, it is also possible to add other film structures between two adjacent structures, so that the two structures are not directly stacked on each other, for example, it is also possible to add other film structures between the composite film and the substrate according to the actual design requirement, and it is also possible to add other film structures between the first electrode and the piezoelectric functional film or between the piezoelectric functional film and the second electrode.
It should be noted that the specific structural form and the specific position of the transversal acoustic wave reflector 4 are not limited, and may be specifically selected according to the actual situation, for example, in the first embodiment, the transversal acoustic wave reflector 4 is a closed ring structure, the transversal acoustic wave reflector 4 is disposed on the first electrode 21, and specifically, the transversal acoustic wave reflector 4 is stacked on the first electrode 21 on the side away from the second electrode 23 and disposed around the longitudinal acoustic wave reflector 3; of course, in other embodiments, an open ring configuration of the transverse acoustic wave reflector is also possible.
Specifically, the substrate 1 includes a bottom wall 11 opposite to and spaced from the first electrode 21, and a ring-shaped sidewall 12 extending from the bottom wall 11 to the first electrode 21 and connected to the surface of the composite film 2; the first electrode 21 is disposed on a side of the sidewall 12 away from the bottom wall 11, and the sidewall 12 acts as the transverse acoustic wave reflector.
Further, the side wall 12 and the bottom wall 11 together enclose a cavity structure, which serves as the longitudinal acoustic wave reflector 3, and the first electrode 21 completely covers the cavity structure.
It should be noted that, an area surrounded by an orthographic projection of the inner side surface 41 of the transverse acoustic wave reflector 4 to the composite film 2 along the first direction is a resonance area 10, and an area of the resonator 100 outside the resonance area 10 is a non-resonance area 20; the first electrode 21, the piezoelectric functional film 22, and the second electrode 23 all completely cover the resonance region 10. The acoustic impedance of the part of the resonator 100 located in the resonance region 10 is different from the acoustic impedance of the part of the resonator 100 located in the non-resonance region 20, so that the acoustic impedance of the resonance region 10 is discontinuous with the acoustic impedance of the non-resonance region 20, and the acoustic impedance of the part of each film layer of the composite film 2 located in the resonance region 10 is substantially constant, in particular, the acoustic impedance of the parts of the first electrode 21, the piezoelectric functional film 22 and the second electrode 23 located in the resonance region 10 is substantially constant; more specifically, the acoustic impedance of the portion of the composite film 2 located in the resonance region 10 is greater than the acoustic impedance of the portion of the composite film 2 located in the non-resonance region 20.
In this embodiment, the piezoelectric functional film 22 includes a longitudinal piezoelectric film 221 located in the resonance region 10 and disposed on the first electrode 21, and a longitudinal non-piezoelectric film 222 disposed around an outer periphery of the longitudinal piezoelectric film 221 and disposed on the first electrode 21, specifically, in this embodiment, the longitudinal piezoelectric film 221 is stacked on a side of the first electrode 21 away from the substrate 1, and the longitudinal non-piezoelectric film 222 is stacked on a side of the first electrode 21 away from the substrate 1; the piezoelectric functional film 22 has a piezoelectric coefficient in the first direction, and more specifically, the longitudinal piezoelectric film 221 has a piezoelectric coefficient in the first direction; the piezoelectric coefficient of the longitudinal non-piezoelectric film 222 along the first direction is zero or smaller than the piezoelectric coefficient of the longitudinal piezoelectric film 221 along the first direction.
Further, the longitudinal piezoelectric film 221 and the longitudinal non-piezoelectric film 222 are made of two different materials; or, the longitudinal piezoelectric film 221 and the longitudinal non-piezoelectric film 222 are made of two same materials with different crystallization characteristics; further, the longitudinal non-piezoelectric film 222 is a composite structure composed of two or more films with different materials.
The resonance region 10 is composed of an excitation region 101 and a non-excitation region 102, wherein the excitation region 101 is formed by a portion of the composite film 2 falling on a region surrounded by the outer side 2210 of the longitudinal piezoelectric film 221 along the first direction, and the non-excitation region 102 is disposed around an outer peripheral side of the excitation region 101, and actually, the non-excitation region 102 is a difference between the resonance region 10 and the excitation region 101. It should be noted that the acoustic impedance of the portions of the composite film 2 located in the resonance region 10 is substantially constant, and in this embodiment, the acoustic impedance of the portions of the first electrode 21, the piezoelectric functional film 22, and the second electrode 23 located in the resonance region 10 is substantially constant. Specifically, the acoustic impedance of the part of the composite film 2 located in the excitation region 101 is unchanged, and the acoustic impedance of the part of the composite film 2 located in the non-excitation region 102 is within 30% of the upper and lower fluctuation of the acoustic impedance of the part of the composite film 2 located in the excitation region 101. In the present embodiment, the acoustic impedance of the part of the longitudinal non-piezoelectric film 222 in the non-excitation region 102 corresponding to 70% to 130% of the acoustic impedance of the longitudinal piezoelectric film 221 can be regarded as the acoustic impedance of the part of the piezoelectric functional film 22 in the resonance region 10 being substantially constant. Similarly, when the acoustic impedances of the first electrode 21 and the second electrode 23 in the excitation region 101 and the non-excitation region 102 satisfy the above-described relationship, it can be considered that the acoustic impedances of the portions of the first electrode 21 and the second electrode 23 in the resonance region 10 are substantially constant.
In the above structure, when the resonator 100 operates, a longitudinal sound wave S1 (which is a working mode sound wave) and a transverse sound wave S2 (which is a non-working mode sound wave) are excited in a portion of the composite membrane 2 located in the excitation region 101, the longitudinal sound wave S1 is confined in the composite membrane 2 by the upper and lower reflective interfaces, and the transverse sound wave S2 propagates from the inside of the composite membrane 2 in a direction perpendicular to the first direction.
Since the acoustic impedance of the non-excitation region 102 is the same as that of the excitation region 101, when the transverse sound wave S2 passes through the interface between the excitation region 101 and the non-excitation region 102, the sound wave scattering effect of the transverse sound wave S2 is avoided, the phenomenon of scattering loss of the sound wave energy of the transverse sound wave S2 is effectively reduced, and most of the sound wave energy of the transverse sound wave S2 is ensured to be transmitted and propagate forwards; since the acoustic impedance of the non-excitation region 102 is smaller than that of the non-resonance region 20, when the transverse sound wave S2 passes through the interface between the non-excitation region 102 and the non-resonance region 20, most of the sound wave energy of the transverse sound wave S2 is mainly returned to the resonance region 10 by sound wave reflection and propagates, and only a small part of the energy will generate sound wave scattering effect, so that the most of the transverse sound wave S2 is effectively prevented from entering the non-resonance region 20 to form energy loss; in practical applications, when the width of the non-excited region 102 is controlled to be small enough, the lateral incident wave and the reflected wave will not form a standing wave resonance in the non-excited region 102, thereby avoiding the formation of a parasitic mode of the lateral sound wave S2 and further ensuring the sound wave energy of the lateral sound wave S2.
Referring to fig. 4, it is apparent that the impedance curve of the resonator 100 of the present invention is closer to the impedance curve of the resonator of the related art near the left trough position, and the impedance curve of the resonator of the present invention is clearly different from the impedance curve of the resonator of the related art near the peak position, and it can be seen from the figure that the impedance curve of the resonator 100 of the present invention has a sharper peak position and a higher impedance peak, that is, the Q value of the resonator 100 of the present invention is higher.
In the above structure, the acoustic impedance of the portion of the composite film 2 located in the resonant region 10 is not continuous with the acoustic impedance of the portion of the composite film 2 located in the non-resonant region 20 by the arrangement of the transverse acoustic wave reflector 4, at this time, the inner side surface 41 of the transverse acoustic wave reflector 4 serves as an interface between the resonant region 10 and the non-resonant region 20, so that the acoustic impedance of the composite film on both sides of the inner side surface 41 of the transverse acoustic wave reflector 4 is not continuous, and in the outward propagation process of the transverse acoustic wave S2, only a primary acoustic wave scattering effect occurs at the inner side surface 41 of the transverse acoustic wave reflector 4, and most of the acoustic wave energy of the transverse acoustic wave S2 is mainly returned to the resonant region 10 by the acoustic wave reflection effect and propagated, thereby effectively ensuring the acoustic wave energy of the transverse acoustic wave S2, and therefore, under the cooperation effect of the longitudinal acoustic wave reflector 3, the Q value of the anti-resonance point is greatly improved, so that a larger Q value of the device is obtained.
Further, in order to ensure that the excitation region 101 is located in the resonance region 10, the orthographic projection of the longitudinal piezoelectric film 221 to the transverse acoustic wave reflector 4 along the first direction completely falls within the area enclosed by the inner side surface 41 of the transverse acoustic wave reflector 4.
Second embodiment
Referring to fig. 5 to 7, a resonator 100a of the second embodiment is shown, the resonator 100a of the second embodiment is substantially a derivative embodiment of the sound generating device of the first embodiment, the structures of the two are basically the same, and the description of the same parts is omitted, and the resonator 100a of the second embodiment mainly differs in that:
the transverse acoustic wave reflector 4a is arranged on the side of the piezoelectric functional film 22a far away from the first electrode 21a and at least partially arranged around the second electrode 23a, and the inner side surface 41a of the transverse acoustic wave reflector 4a is abutted against the second electrode 23 a; more specifically, the transverse acoustic wave reflector 4a is stacked on the side of the longitudinal non-piezoelectric film 222a away from the first electrode 21a, and the transverse acoustic wave reflector 4a is an open ring that is not completely closed.
It is worth mentioning that the material density of the transverse acoustic wave reflector 4a is different from the material density of the second electrode 23a, so that the acoustic impedance of the transverse acoustic wave reflector 4a is different from the acoustic impedance of the second electrode 23a, and thus the acoustic impedance between the two electrodes is discontinuous, for example, in the second embodiment, the material density of the transverse acoustic wave reflector 4a is greater than the material density of the second electrode 23a, so that the acoustic impedance of the transverse acoustic wave reflector 4a is greater than the acoustic impedance of the second electrode 23 a.
The substrate 1a includes a bottom wall 11a opposite to and spaced from the first electrode 21a, and a side wall 12a bent and extended from the bottom wall 11a to the first electrode 21a and having a ring shape, the side wall 12a and the bottom wall 11a together enclose a cavity structure, the cavity structure serves as a longitudinal acoustic wave reflector 3a, the first electrode 21a is disposed on a side of the side wall 12a away from the bottom wall 11a, and specifically, the first electrode 21a is stacked on a surface of the side wall 12a away from the bottom wall 11a and completely covers the cavity structure.
It should be noted that, the specific forming manner of the longitudinal acoustic wave reflector 3a is not limited, and it may be specifically configured according to the actual situation, for example, in the present embodiment, the longitudinal acoustic wave reflector 3a is a cavity structure formed by recessing the substrate 1a from the side close to the first electrode 21a to the direction away from the first electrode 21a, and the first electrode 21a covers the cavity structure; of course, in other embodiments, it is also possible that the longitudinal acoustic wave reflector is a bragg acoustic mirror disposed on a side of the substrate close to the first electrode, and the first electrode is disposed on a side of the bragg acoustic mirror away from the substrate, that is, in this case, the first electrode is directly stacked on the longitudinal acoustic wave reflector.
It is worth mentioning that the forward projection of the area enclosed by the inner side surface 41a of the transversal sound wave reflector 4a to the longitudinal sound wave reflector 3a along the first direction at least partially falls within the range of the longitudinal sound wave reflector 3 a.
Compared with the prior art, in the resonator, the closed or opened annular transverse sound wave reflector is arranged on the surface of the composite film, the area surrounded by the orthographic projection of the inner side surface of the transverse sound wave reflector to the composite film along the first direction is a resonance area, and the area of the resonator outside the resonance area is a non-resonance area; the first electrode, the piezoelectric functional film and the second electrode completely cover the resonance area; the piezoelectric functional film comprises a longitudinal piezoelectric film which is positioned in the resonance area and arranged on one side of the first electrode, which is far away from the substrate, and a longitudinal non-piezoelectric film which surrounds the outer periphery of the longitudinal piezoelectric film and is arranged on one side of the first electrode, which is far away from the substrate; the acoustic impedance of the part of the resonator, which is positioned in the resonance area, is different from the acoustic impedance of the part of the resonator, which is positioned in the non-resonance area, and the acoustic impedances of the parts of the first electrode, the piezoelectric functional film and the second electrode, which are positioned in the resonance area, are all approximately unchanged; in the structure, the acoustic impedance of the part of the resonator in the resonance area and the acoustic impedance of the part of the resonator in the non-resonance area are discontinuous through the arrangement of the transverse sound wave reflector, the inner side surface of the transverse sound wave reflector serves as an interface of the resonance area and the non-resonance area, the acoustic impedances of the composite film on two sides of the inner side surface of the transverse sound wave reflector are discontinuous, in the outward propagation process of transverse sound waves, a sound wave scattering effect only occurs on the inner side surface of the transverse sound wave reflector, and the transverse sound wave reflector mainly has a sound wave reflection effect on the transverse sound waves, so that under the combined action of the longitudinal sound wave reflector and the transverse sound wave reflector, transverse wave resonance is less and weaker, and the Q value of an anti-resonance point is.
While the foregoing is directed to embodiments of the present invention, it will be understood by those skilled in the art that various changes may be made without departing from the spirit and scope of the invention.
Claims (12)
1. A resonator comprises a substrate, a composite film arranged above the substrate along a first direction, and a longitudinal acoustic wave reflector arranged on one side, close to the substrate, of the composite film, wherein the composite film comprises a first electrode, a piezoelectric functional film and a second electrode which are sequentially arranged along the first direction, and the first electrode is arranged on the substrate and the longitudinal acoustic wave reflector; the resonator also comprises a closed or opened annular transverse sound wave reflector arranged on the surface of the composite film, the area surrounded by the orthographic projection of the inner side surface of the transverse sound wave reflector to the composite film along the first direction is a resonance area, and the area of the resonator outside the resonance area is a non-resonance area; the first electrode, the piezoelectric functional film and the second electrode all completely cover the resonance region; the piezoelectric functional film comprises a longitudinal piezoelectric film which is positioned in the resonance area and arranged on one side of the first electrode away from the substrate, and a longitudinal non-piezoelectric film which surrounds the outer periphery of the longitudinal piezoelectric film and is arranged on one side of the first electrode away from the substrate; the acoustic impedance of the portion of the resonator located in the resonance region is different from the acoustic impedance of the portion of the resonator located in the non-resonance region, and the acoustic impedances of the first electrode, the piezoelectric functional film, and the portion of the second electrode located in the resonance region are all substantially constant.
2. The resonator of claim 1, wherein the saw reflector is disposed on a side of the first electrode remote from the second electrode and around the saw reflector.
3. The resonator according to claim 2, wherein the substrate comprises a bottom wall spaced opposite to the first electrode, and a ring-shaped sidewall extending from the bottom wall to the first electrode, the first electrode is disposed on a side of the sidewall away from the bottom wall, and the sidewall acts as the transverse acoustic wave reflector.
4. The resonator according to claim 3, wherein said side walls and said bottom wall together enclose a cavity structure, said cavity structure acting as said longitudinal acoustic wave reflector, said first electrode completely covering said cavity structure.
5. The resonator according to claim 1, wherein the saw-wave reflector is disposed on a side of the piezoelectric functional film away from the first electrode and at least partially surrounding the second electrode, an inner side surface of the saw-wave reflector abuts against the second electrode, and an acoustic impedance of the saw-wave reflector is different from an acoustic impedance of the second electrode.
6. The resonator of claim 5, wherein an acoustic impedance of the transverse acoustic wave reflector is greater than an acoustic impedance of the second electrode.
7. The resonator according to claim 5, wherein the substrate comprises a bottom wall opposite to and spaced from the first electrode, and a side wall extending from the bottom wall to the first electrode in a bent manner, the side wall and the bottom wall jointly enclose a cavity structure, the cavity structure acts as the longitudinal acoustic wave reflector, and the first electrode is disposed on a side of the side wall away from the bottom wall.
8. The resonator of claim 5, wherein the longitudinal acoustic wave reflector is a Bragg acoustic mirror disposed on a side of the substrate proximate the first electrode, the first electrode being disposed on a side of the Bragg acoustic mirror distal from the substrate.
9. The resonator according to claim 7 or 8, characterized in that the forward projection of the area enclosed by the inner side surfaces of the saw reflectors in the first direction to the saw reflectors at least partially falls within the range of the saw reflectors.
10. The resonator of claim 1, wherein an orthographic projection of the longitudinal piezoelectric film in the first direction onto the saw reflector falls entirely within an area bounded by inner sides of the saw reflector.
11. The resonator according to claim 1, wherein a portion of the composite film falling on an area surrounded by outer sides of the longitudinal piezoelectric films in the first direction forms an excitation region, the excitation region being located within the resonance region.
12. The resonator of claim 1, wherein the longitudinal piezoelectric film has a piezoelectric coefficient in the first direction, and wherein the piezoelectric coefficient of the longitudinal non-piezoelectric film in the first direction is zero or less than the piezoelectric coefficient of the longitudinal piezoelectric film in the first direction.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010664307.7A CN111884619A (en) | 2020-07-10 | 2020-07-10 | Resonator having a dielectric layer |
| PCT/CN2020/122534 WO2022007238A1 (en) | 2020-07-10 | 2020-10-21 | Resonator |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010664307.7A CN111884619A (en) | 2020-07-10 | 2020-07-10 | Resonator having a dielectric layer |
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| CN111884619A true CN111884619A (en) | 2020-11-03 |
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| CN202010664307.7A Withdrawn CN111884619A (en) | 2020-07-10 | 2020-07-10 | Resonator having a dielectric layer |
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| CN (1) | CN111884619A (en) |
| WO (1) | WO2022007238A1 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9425764B2 (en) * | 2012-10-25 | 2016-08-23 | Avago Technologies General Ip (Singapore) Pte. Ltd. | Accoustic resonator having composite electrodes with integrated lateral features |
| CN109889179A (en) * | 2018-12-26 | 2019-06-14 | 天津大学 | Resonator and ladder-type filter |
| CN109889177B (en) * | 2018-12-26 | 2023-04-07 | 天津大学 | Bulk acoustic wave resonator with doped isolation structure |
| CN110868173B (en) * | 2019-04-23 | 2023-08-15 | 中国电子科技集团公司第十三研究所 | Resonator and filter |
| CN110311643A (en) * | 2019-08-01 | 2019-10-08 | 杭州左蓝微电子技术有限公司 | A kind of thin film bulk acoustic wave resonator and preparation method thereof |
| CN111010116B (en) * | 2019-08-13 | 2023-12-15 | 天津大学 | Bulk acoustic resonator with highly graded bump structure, filter, and electronic device |
| CN111884620A (en) * | 2020-07-10 | 2020-11-03 | 瑞声科技（南京）有限公司 | Resonator having a dielectric layer |
| CN111884618A (en) * | 2020-07-10 | 2020-11-03 | 瑞声科技（南京）有限公司 | Resonator having a dielectric layer |
-
2020
- 2020-07-10 CN CN202010664307.7A patent/CN111884619A/en not_active Withdrawn
- 2020-10-21 WO PCT/CN2020/122534 patent/WO2022007238A1/en active Application Filing
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| WO2022007238A1 (en) | 2022-01-13 |
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