CN215072338U - Acoustic resonator for exciting shear mode in thickness direction - Google Patents
Acoustic resonator for exciting shear mode in thickness direction Download PDFInfo
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- CN215072338U CN215072338U CN202120532330.0U CN202120532330U CN215072338U CN 215072338 U CN215072338 U CN 215072338U CN 202120532330 U CN202120532330 U CN 202120532330U CN 215072338 U CN215072338 U CN 215072338U
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Abstract
The utility model relates to an acoustic syntonizer of thickness direction excitation shear mode, include: the acoustic mirror comprises at least one first acoustic reflection layer and at least one second acoustic reflection layer, and the acoustic impedance of each first acoustic reflection layer is smaller than that of each second acoustic reflection layer; a bottom electrode layer on the acoustic mirror; the piezoelectric layer is arranged on the bottom electrode layer and comprises lithium niobate of a single crystal material and/or lithium tantalate of a single crystal material; an electrode unit disposed on the piezoelectric layer; a transverse reflector disposed on the piezoelectric layer, the transverse reflector for transversely reflecting the acoustic wave; wherein the bottom electrode layer and the electrode unit are used for forming an electric field. The utility model discloses can have high electromechanical coupling coefficient and high Q value under the frequency more than 3 GHz.
Description
Technical Field
The application relates to the technical field of resonators, in particular to an acoustic resonator in a thickness direction shear mode.
Background
Radio frequency acoustic resonators are small, micro-synthetic structures used for synthesis filtering functions or as frequency sources. The acoustic resonator has a smaller volume and a higher quality factor (Q), so that other types of resonators used in mobile phones, small base stations and Internet of things equipment are replaced, and the acoustic resonator can achieve low loss (low power consumption), high suppression and high signal-to-noise ratio and ultrathin packaging.
With the release of new communication standards (i.e., fifth generation mobile networks), it is necessary to extend the operating range of the resonator to higher frequencies while maintaining a high electromechanical coupling coefficient and a high Q value.
SUMMERY OF THE UTILITY MODEL
Based on this, it is necessary to provide an acoustic resonator capable of a thickness direction shear mode having a high electromechanical coupling coefficient and a high Q value at a frequency of 3GHz or more.
An acoustic resonator for thickness-wise excitation of shear modes, comprising: the acoustic mirror comprises at least one first acoustic reflection layer and at least one second acoustic reflection layer, and the acoustic impedance of each first acoustic reflection layer is smaller than that of each second acoustic reflection layer; a bottom electrode layer on the acoustic mirror; the piezoelectric layer is arranged on the bottom electrode layer and comprises lithium niobate of a single crystal material and/or lithium tantalate of a single crystal material; an electrode unit disposed on the piezoelectric layer; the transverse reflector is arranged on the piezoelectric layer and comprises a first reflector positioned on a first side of the electrode unit and a second reflector positioned on a second side of the electrode unit, the first side and the second side are opposite sides, and the transverse reflector is used for transversely reflecting the sound wave; wherein the bottom electrode layer and the electrode unit are used for forming an electric field.
In one embodiment, the direction of the electric field formed by the bottom electrode layer and the electrode unit is mainly the thickness direction of the piezoelectric layer, and the bottom electrode layer and the electrode unit are also used for generating mechanical waves in a shear mode throughout the thickness of the piezoelectric layer.
In one embodiment, the thickness of the first acoustic reflective layer is thicker the farther away from the bottom electrode layer; the thickness of the second acoustic reflection layer farther from the bottom electrode layer is thicker.
In one embodiment, the acoustic mirror includes three first acoustic reflection layers and two second acoustic reflection layers, and the first acoustic reflection layers and the second acoustic reflection layers are alternately disposed in the acoustic mirror.
In one embodiment, the material of the first acoustic reflection layer includes at least one of silicon dioxide, aluminum, benzocyclobutene, polyimide and spin-on glass, and the material of the second acoustic reflection layer includes at least one of molybdenum, tungsten, titanium, platinum, aluminum nitride, tungsten oxide and silicon nitride.
In one embodiment, the electrode unit includes a first common electrode, a second common electrode, a plurality of first interdigital electrodes, and a plurality of second interdigital electrodes, each of the first interdigital electrodes is electrically connected to the first common electrode, each of the second interdigital electrodes is electrically connected to the second common electrode, and each of the first interdigital electrodes and each of the second interdigital electrodes are arranged in an insulated manner, the first common electrode is used for accessing an input voltage, and the second common electrode is used for grounding.
In one embodiment, the piezoelectric device further includes a passivation layer disposed on the piezoelectric layer, and the passivation layer covers each of the first interdigital electrodes and each of the second interdigital electrodes.
In one embodiment, a connecting line direction between the transverse reflectors on both sides of the electrode unit is a propagation direction of the acoustic wave; the width of the bottom electrode layer is smaller than the distance between the first common electrode and the second common electrode, so that the orthographic projection of the bottom electrode layer on the plane of the electrode unit is positioned between the first common electrode and the second common electrode; the orthographic projection of each of the first and second acoustic reflection layers on the plane exceeds the first and second reflectors in the direction of the connecting line.
In one embodiment, an orthographic projection of each second acoustic reflection layer on a plane where the bottom electrode layer is located exceeds two sides of the bottom electrode layer in the first direction, or an orthographic projection of each first acoustic reflection layer and each second acoustic reflection layer on the plane where the bottom electrode layer is located is covered by the bottom electrode layer; the first direction is parallel to a propagation direction of the acoustic wave.
In one embodiment, the first reflector and the second reflector each comprise at least one electrode strip, the distance between the center of the closest electrode strip to the electrode unit and the center of the interdigital electrode at the first side edge of the electrode unit in the first reflector is 1/8-2 wavelengths of the acoustic wave, and the distance between the center of the closest electrode strip to the electrode unit and the center of the interdigital electrode at the second side edge of the electrode unit in the second reflector is 1/8-2 wavelengths of the acoustic wave.
In one embodiment, the display device further includes a first metal piece disposed on the first common electrode and a second metal piece disposed on the second common electrode, wherein thicknesses of the first metal piece and the second metal piece are greater than a thickness of the electrode unit, the first metal piece and the second metal piece are configured to perform acoustic reflection in a second direction, and the second direction is perpendicular to a propagation direction of the acoustic wave.
In one embodiment, the electrode unit and the transverse reflector are made of the same material and are made of metal and/or alloy.
In one embodiment, there is a first acoustic reflective layer that is closer to the bottom electrode layer than all of the second acoustic reflective layers.
The acoustic resonator exciting the shear mode in the thickness direction generates an electric field through the electrode unit and the bottom electrode layer, and laterally reflects the sound wave through the lateral reflector, so that the acoustic resonator can be excited to be in the shear vibration mode in the thickness direction, and can have a high electromechanical coupling coefficient and a high Q value at a frequency of more than 3 GHz.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments or the conventional technologies of the present application, the drawings used in the descriptions of the embodiments or the conventional technologies will be briefly introduced below, it is obvious that the drawings in the following descriptions are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a top view of a portion of the structure of an acoustic resonator with thickness-direction excited shear modes in one embodiment;
FIG. 2 is a cross-sectional view taken along line A-A' of FIG. 1;
FIG. 3 is a schematic view of the propagation directions of the electric field and the mechanical wave in the piezoelectric layer;
FIG. 4 is a schematic thickness diagram of the reflective layers of the mirror in one embodiment;
FIG. 5 is a schematic diagram of a first reflector in one embodiment;
FIG. 6 is a cross-sectional view taken along line B-B' of FIG. 1;
FIG. 7 shows an embodiment of WgSchematic of (a);
FIG. 8 is a simulation result of the characteristic admittance of an acoustic resonator with thickness-direction excited shear mode of an embodiment.
Detailed Description
To facilitate an understanding of the present application, the present application will now be described more fully with reference to the accompanying drawings. Embodiments of the present application are set forth in the accompanying drawings. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
It will be understood that when an element or layer is referred to as being "on," "adjacent to," "connected to," or "coupled to" other elements or layers, it can be directly on, adjacent to, connected or coupled to the other elements or layers or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on," "directly adjacent to," "directly connected to" or "directly coupled to" other elements or layers, there are no intervening elements or layers present. It will be understood that, although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers, doping types and/or sections, these elements, components, regions, layers, doping types and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, doping type or section from another element, component, region, layer, doping type or section. Thus, a first element, component, region, layer, doping type or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention; for example, the first doping type may be made the second doping type, and similarly, the second doping type may be made the first doping type; the first doping type and the second doping type are different doping types, for example, the first doping type may be P-type and the second doping type may be N-type, or the first doping type may be N-type and the second doping type may be P-type.
Spatial relational terms, such as "under," "below," "under," "over," and the like may be used herein to describe one element or feature's relationship to another element or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements or features described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary terms "under" and "under" can encompass both an orientation of above and below. In addition, the device may also include additional orientations (e.g., rotated 90 degrees or other orientations) and the spatial descriptors used herein interpreted accordingly.
As used herein, the singular forms "a", "an" and "the" may include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises/comprising," "includes" or "including," etc., specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof. Also, in this specification, the term "and/or" includes any and all combinations of the associated listed items.
Embodiments of the invention are described herein with reference to cross-sectional illustrations that are schematic illustrations of idealized embodiments (and intermediate structures) of the invention, such that variations from the shapes shown are to be expected due to, for example, manufacturing techniques and/or tolerances. Thus, embodiments of the present invention should not be limited to the particular shapes of regions illustrated herein, but are to include deviations in shapes that result, for example, from manufacturing techniques. For example, an implanted region shown as a rectangle will typically have rounded or curved features and/or implant concentration gradients at its edges rather than a binary change from implanted to non-implanted region. Also, a buried region formed by implantation may result in some implantation in the region between the buried region and the surface through which the implantation is performed. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the actual shape of a region of a device and are not intended to limit the scope of the present invention.
Bulk Acoustic Wave (BAW) and Surface Acoustic Wave (SAW) resonators are the most common devices for synthesizing filters and resonators between 0.6GHz and 3 GHz. These acoustic devices are commercially successful and are widely used in handset front end modules or as discrete components of radio front ends. Existing bulk acoustic wave and surface acoustic wave devices can exhibit Q values in excess of 1000 and electromechanical coupling coefficients of about 7% -10% at frequencies below 3 GHz. Extending its frequency operating range above 3GHz suffers from several technical uncertainties and physical limitations. The new 5G standard requires electromechanical coupling coefficients in excess of 10%, which cannot be achieved with bulk acoustic wave and surface acoustic wave devices without changing the materials of construction or the mode of operation. Also, material loss constitutes a fundamental limitation on the maximum Q achievable with conventional bulk acoustic wave and surface acoustic wave devices beyond 3 GHz.
In summary, the market demands new devices that can have high electromechanical coupling and high quality factor at frequencies above 3 GHz.
The present application aims to develop a new type of wafer level mechanical/acoustic resonator that is capable of high Q-value and high electromechanical coupling coefficient at frequencies above 3 GHz. The resonator will support the synthesis of high performance pass band filters to meet the new requirements and future generations of the 5G communication standard.
Fig. 1 is a plan view of a partial structure of an acoustic resonator for thickness-direction excitation of a shear mode in one embodiment, and fig. 2 is a sectional view taken along line a-a' in fig. 1. Referring to fig. 1 and 2, the acoustic resonator for exciting a shear mode in a thickness direction includes an acoustic mirror 120, a bottom electrode layer 170, a piezoelectric layer 130, an electrode unit, and a transverse reflector, and fig. 1 is mainly for illustrating shapes of the electrode unit and the transverse reflector in the corresponding embodiment, so that other structures on the piezoelectric layer 130 are omitted.
The electrode unit is provided on the piezoelectric layer 130. The electrode unit may include interdigitated electrodes. In the embodiment shown in fig. 1 and 2, the electrode unit includes a set of first interdigital electrodes 141 and a set of second interdigital electrodes 143, the first interdigital electrodes 141 and the second interdigital electrodes 143 extend in the Y direction in fig. 1 and are therefore parallel to each other, each first interdigital electrode 141 and each second interdigital electrode 143 are arranged in an insulated manner, the first interdigital electrodes 141 are used for receiving an input voltage, and the second interdigital electrodes 143 are used for grounding. The electrode unit further includes a first common electrode 142 and a second common electrode 144, one end of each first interdigital electrode 141 is connected to the first common electrode 142, one end of each second interdigital electrode 143 is connected to the second common electrode 144, and the common electrodes are also referred to as bus bars.
The transverse reflectors, which are also provided on the piezoelectric layer 130, may be provided in the same layer as the electrode units, including a first reflector 152 on a first side (left side in fig. 1) of the electrode unit and a second reflector 154 on a second side (right side in fig. 1) of the electrode unit. The transverse reflector is insulated from the electrode unit and is used for transversely reflecting the sound wave.
The piezoelectric layer 130 is disposed on the bottom electrode layer 170. The piezoelectric layer 130 includes lithium niobate of a single crystal material and/or lithium tantalate of a single crystal material.
The bottom electrode layer 170 is provided on the acoustic mirror 120. The bottom electrode layer 170 and the electrode units are used to form an electric field.
The acoustic mirror 120 includes at least one first acoustic reflective layer and at least one second acoustic reflective layer, each first acoustic reflective layer having an acoustic impedance less than an acoustic impedance of each second acoustic reflective layer. In one embodiment of the present application, the layer of the acoustic mirror 120 closest to the bottom electrode layer 170 should be the first acoustic reflective layer, i.e., there is a first acoustic reflective layer that is closer to the bottom electrode layer 170 than all of the second acoustic reflective layers. In the embodiment shown in fig. 2, the acoustic mirror 120 includes three first acoustic reflective layers (i.e., the first acoustic reflective layer 121, the first acoustic reflective layer 123, the first acoustic reflective layer 125) and two second acoustic reflective layers (i.e., the second acoustic reflective layer 122 and the second acoustic reflective layer 124), each of which is alternately disposed.
The acoustic resonator exciting the shear mode in the thickness direction generates an electric field through the electrode unit and the bottom electrode layer, and laterally reflects the sound wave through the lateral reflector, so that the acoustic resonator can be excited to be in the shear vibration mode in the thickness direction, and can have a high electromechanical coupling coefficient and a high Q value at a frequency of more than 3 GHz.
Further, since the piezoelectric layer 130 uses lithium niobate or lithium tantalate which is a single crystal material, it is also helpful to have a high electromechanical coupling coefficient and a high Q value at frequencies above 3 GHz. Referring to fig. 3, the large arrows indicate the direction of the electric field, the small arrows indicate the propagation direction of the mechanical wave in the shear vibration mode, and the direction of the electric field is mainly the thickness direction of the piezoelectric layer 130. The bottom electrode layer 170 and electrode unit also serve to generate mechanical waves in shear mode throughout the thickness of the piezoelectric layer 130. The lithium niobate/lithium tantalate of the single crystal material is matched with the electrode unit structure and the transverse reflector structure of the device, so that an optimized shear vibration mode can be obtained, the shear vibration mode has a higher acoustic wave speed, and the frequency can be higher than that of a traditional commercial filter under the condition that the key size (such as the step pitch of the interdigital) of the device is not changed.
In one embodiment of the present application, the electrode unit and the transverse reflector are made of the same material and are made of metal and/or alloy. In one embodiment of the present application, the electrode unit may be made of aluminum (Al), copper (Cu), aluminum copper (AlCu), aluminum silicon copper (AlSiCu), molybdenum (Mo), tungsten (W), silver (Ag), or any other conductive metal.
In one embodiment of the present application, the material of the bottom electrode layer 170 may include one or more of molybdenum, tungsten, ruthenium, platinum, titanium, aluminum copper, aluminum silicon copper, and chromium.
In the embodiment shown in fig. 2, the thickness-wise excited shear mode acoustic resonator further comprises a carrier wafer 110. The acoustic mirror 120 is disposed on the carrier wafer 110.
In an embodiment of the present application, a bonding auxiliary layer is further disposed between the carrier wafer 110 and the acoustic mirror 120, for assisting the bonding between the carrier wafer 110 and the acoustic mirror 120. In one embodiment of the present application, the bonding assistance layer is a thin layer of silicon dioxide.
In one embodiment of the present application, the first acoustic reflective layers are made of a low acoustic impedance material, and the second acoustic reflective layers are made of a high acoustic impedance material. Wherein the low acoustic impedance material may be at least one of silicon dioxide, aluminum, Benzocyclobutene (BCB), polyimide, and spin on glass (spin on glass), and the high acoustic impedance material may be at least one of molybdenum, tungsten, titanium, platinum, aluminum nitride, aluminum oxide, tungsten oxide, and silicon nitride; it will be appreciated that in other embodiments, other combinations of materials having a greater impedance ratio may be used for the low acoustic impedance material and the high acoustic impedance material.
Each of the first and second acoustic reflective layers of the acoustic mirror 120 may have equal or unequal thicknesses. In one embodiment of the present application, the thicker the thickness of the first acoustic reflection layer the farther from the bottom electrode layer 170; this design can achieve a larger Q value as the thickness of the second acoustic reflective layer is thicker the farther away from the bottom electrode layer 170. Referring to fig. 4, in the embodiment shown in fig. 4, the thickness Tl1 of the first acoustic reflection layer 121 < the thickness Tl2 of the first acoustic reflection layer 123 < the thickness Tl3 of the first acoustic reflection layer 125, and the thickness Th1 of the second reflection layer 122 < the thickness Th2 of the second reflection layer 124. It is understood that in other embodiments, the thickness relationship between the first acoustic reflective layer and the second acoustic reflective layer may be set according to other rules, for example, Tl1 ═ Tl2 ═ Tl3, Th1 ═ Th 2; or Tl1> Tl2> Tl3, Th1> Th 2; or Tl1< Tl2, Tl3< Tl2, and Th1< Th 2.
Fig. 1 also shows the position of the acoustic mirror 120 in a top view. The X direction in fig. 1 is the propagation direction of the acoustic wave. The bottom electrode layer 170 is formed by patterning, and the width in the Y direction thereof may be the same as or different from (may be larger or smaller than) the width in the Y direction of the acoustic mirror 120. The width of the bottom electrode layer 170 (i.e., the dimension in the Y direction in fig. 1) is smaller than the distance between the first common electrode 142 and the second common electrode 144, so that the bottom electrode layer 170 is located between the first common electrode 142 and the second common electrode 144 in the Y direction in the orthographic projection of the electrode unit on the plane. In the embodiment shown in fig. 1, a side of the bottom electrode layer 170 near the first common electrode 142 in the orthographic projection exceeds an end of each second interdigital electrode 143 near the first common electrode 142, and a side of the bottom electrode layer near the second common electrode 144 exceeds an end of each first interdigital electrode 141 near the second common electrode 144, that is, the bottom electrode layer 170 is wide enough to make two sides of the orthographic projection fall outside the second interdigital electrode 143/outside the first interdigital electrode 141.
In the embodiment shown in fig. 1, the bottom electrode layer 170 has a length and a width that are both larger than the acoustic mirror 120, thereby covering the acoustic mirror 120 in both the X-direction and the Y-direction.
The first acoustic reflection layer and the second acoustic reflection layer may be the same or different in X-direction dimension. In the embodiment shown in fig. 1, the orthographic projection of each of the first and second acoustic reflection layers on the plane of the electrode unit exceeds the first and second reflectors 152 and 154 in the X direction, i.e., the left edge of the orthographic projection falls further to the left of the left edge of the first reflector 152 and the right edge falls further to the right of the right edge of the second reflector 154.
In the embodiment shown in fig. 1, orthographic projections of the respective first and second acoustic reflection layers on the plane of the bottom electrode layer 170 are covered by the bottom electrode layer 170 in the X direction (i.e., the lengths of the first and second acoustic reflection layers in the X direction are smaller than the length of the bottom electrode layer 170 in the X direction). In another embodiment of the present application, an orthographic projection of each second acoustic reflection layer on the plane of the bottom electrode layer 170 exceeds two sides of the bottom electrode layer 170 in the X direction, that is, the length of the second acoustic reflection layer in the X direction is greater than the length of the bottom electrode layer 170 in the X direction.
The electrode strips of the transverse reflectors may be disconnected from each other as shown in fig. 5, or may be connected to each other by a transverse structure as shown in fig. 1. The electrode strips of the transverse reflector may be arranged parallel to the fingers of the electrode unit.
Fig. 6 is a sectional view taken along line B-B' in fig. 1. In this embodiment, the area of the acoustic mirror 120 and the bottom electrode layer 170 is smaller than the area of the piezoelectric layer 130 and the carrier wafer 110, so a filling layer is further disposed around the acoustic mirror 120 (and the bottom electrode layer 170). In one embodiment of the present disclosure, the material of the filling layer may include one or more of silicon dioxide, molybdenum, tungsten oxide, or silicon nitride. In one embodiment of the present application, the material of the filling layer is the same as the material of each first acoustic reflection layer, which improves the quality factor of the acoustic resonator.
In the embodiment shown in fig. 6, the acoustic resonator for thickness-wise excitation of shear modes further includes a first metallic piece 145 provided on the first common electrode 141 and a second metallic piece 147 provided on the second common electrode 143. The thicknesses of the first and second metal pieces 145 and 147 are greater than the thickness of the electrode unit. The first metal piece 145 and the second metal piece 147 serve to make acoustic reflection in the Y direction in fig. 1.
In one embodiment of the present application, the distance W between the center of the electrode bar closest to the electrode element in the first reflector 152 and the center of the inter-digital electrode at the first side edge of the electrode elementg(refer to fig. 7) is 1/8 to 2 wavelengths of the acoustic wave; the center of the electrode bar closest to the electrode element in the second reflector 154 and the second side edge of the electrode element are interdigitatedThe center of the pole is 1/8 to 2 acoustic wavelengths apart.
The vibration frequency of the mechanical wave of the shear vibration mode formed in the piezoelectric layer 130 is related to the thickness of each film layer and the spacing between adjacent interdigital electrodes in the electrode unit, and the stress is mainly limited to the area without metal coverage between the first interdigital electrode 141 and the second interdigital electrode 143.
In the embodiment shown in fig. 6, the thickness-wise shear mode excited acoustic resonator further comprises a passivation layer 160. A passivation layer 160 is disposed on the piezoelectric layer 130 and covers the first interdigital electrode 141 and the second interdigital electrode 143. The passivation layer 160 may lower the frequency temperature coefficient of the resonator and passivate the metal electrodes.
Fig. 8 is a simulation result of a Characteristic Admittance (charateristic acceptance) of an acoustic resonator that excites a shear mode in a thickness direction according to an embodiment. Wherein (b) is the local curve of (a), ktIs the electromechanical coupling coefficient. The characteristic frequency simulation was used to obtain an optimized stacked reflector thickness for a resonant frequency of 4.07 GHz. The same eigenfrequency analysis is used to determine the optimal in-plane reflective layer position and the relative position of the reflective layer stack with respect to the interdigital electrodes.
In the description herein, references to the description of "some embodiments," "other embodiments," "desired embodiments," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, a schematic description of the above terminology may not necessarily refer to the same embodiment or example.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features of the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the claims. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. An acoustic resonator for thickness-wise excitation of shear modes, comprising:
the acoustic mirror comprises at least one first acoustic reflection layer and at least one second acoustic reflection layer, and the acoustic impedance of each first acoustic reflection layer is smaller than that of each second acoustic reflection layer;
a bottom electrode layer on the acoustic mirror;
the piezoelectric layer is arranged on the bottom electrode layer and comprises lithium niobate of a single crystal material and/or lithium tantalate of a single crystal material;
an electrode unit disposed on the piezoelectric layer;
a transverse reflector disposed on the piezoelectric layer, the transverse reflector for transversely reflecting the acoustic wave;
wherein the bottom electrode layer and the electrode unit are used for forming an electric field.
2. A thickness direction excited shear mode acoustic resonator as claimed in claim 1, wherein the direction of the electric field formed by the bottom electrode layer and the electrode unit is mainly in the thickness direction of the piezoelectric layer, and the bottom electrode layer and the electrode unit are further configured to generate mechanical waves in a shear mode throughout the thickness of the piezoelectric layer.
3. The thickness-wise excited shear mode acoustic resonator of claim 1, wherein the first acoustic reflective layer is thicker the further away from the bottom electrode layer; the thickness of the second acoustic reflection layer farther from the bottom electrode layer is thicker.
4. The thickness-direction shear mode excited acoustic resonator according to claim 1, wherein the acoustic mirror includes three first acoustic reflection layers and two second acoustic reflection layers, and the first acoustic reflection layers and the second acoustic reflection layers are alternately arranged.
5. The thickness-wise excited shear mode acoustic resonator of claim 1, wherein there is a first acoustic reflective layer closer to the bottom electrode layer than all of the second acoustic reflective layers.
6. The thickness-direction excited shear mode acoustic resonator according to claim 5, wherein the electrode unit comprises a first common electrode, a second common electrode, a plurality of first interdigital electrodes and a plurality of second interdigital electrodes, each of the first interdigital electrodes is electrically connected to the first common electrode, each of the second interdigital electrodes is electrically connected to the second common electrode, and each of the first interdigital electrodes and each of the second interdigital electrodes are insulated from each other, the first common electrode is used for receiving an input voltage, and the second common electrode is used for grounding; the transverse reflectors include a first reflector at a first side of the electrode unit and a second reflector at a second side of the electrode unit, the first and second sides being opposite sides.
7. The thickness-direction shear-mode-excited acoustic resonator according to claim 6, wherein a direction of a line connecting the transverse reflectors on both sides of the electrode unit is a propagation direction of the acoustic wave; the width of the bottom electrode layer is smaller than the distance between the first common electrode and the second common electrode, so that the orthographic projection of the bottom electrode layer on the plane of the electrode unit is positioned between the first common electrode and the second common electrode; the orthographic projection of each of the first and second acoustic reflection layers on the plane exceeds the first and second reflectors in the direction of the connecting line.
8. The thickness-direction shear mode-excited acoustic resonator according to claim 1 or 7, wherein an orthogonal projection of each of the second acoustic reflection layers on the plane of the bottom electrode layer exceeds both sides of the bottom electrode layer in the first direction, or an orthogonal projection of each of the first acoustic reflection layer and the second acoustic reflection layer on the plane of the bottom electrode layer is covered with the bottom electrode layer;
the first direction is parallel to a propagation direction of the acoustic wave.
9. The thickness-direction shear mode-excited acoustic resonator according to claim 6, wherein the first reflector and the second reflector each comprise at least one electrode strip, a center of a closest one of the first reflectors to the electrode element is separated from a center of the interdigital electrode on the first side edge of the electrode element by 1/8 to 2 wavelengths of the acoustic wave, and a center of a closest one of the second reflectors to the electrode element is separated from a center of the interdigital electrode on the second side edge of the electrode element by 1/8 to 2 wavelengths of the acoustic wave.
10. The thickness-direction excited shear mode acoustic resonator according to claim 6, further comprising a first metal member provided on the first common electrode and a second metal member provided on the second common electrode, the first metal member and the second metal member having a thickness larger than that of the electrode unit, the first metal member and the second metal member being configured to perform acoustic reflection in a second direction perpendicular to a propagation direction of the acoustic wave.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120532330.0U CN215072338U (en) | 2021-03-15 | 2021-03-15 | Acoustic resonator for exciting shear mode in thickness direction |
| US18/275,304 US20240120901A1 (en) | 2021-03-15 | 2022-03-11 | Acoustic resonator excited in thickness shear mode |
| KR1020237032661A KR20230148359A (en) | 2021-03-15 | 2022-03-11 | Acoustic resonator in which shear mode is excited in the thickness direction |
| JP2023555612A JP2024509313A (en) | 2021-03-15 | 2022-03-11 | Acoustic resonator that excites shear mode in the thickness direction |
| PCT/CN2022/080450 WO2022194060A1 (en) | 2021-03-15 | 2022-03-11 | Acoustic resonator in thickness direction excited shear mode |
| EP22770415.2A EP4311109A1 (en) | 2021-03-15 | 2022-03-11 | Acoustic resonator in thickness direction excited shear mode |
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| WO2022194060A1 (en) * | 2021-03-15 | 2022-09-22 | 偲百创(深圳)科技有限公司 | Acoustic resonator in thickness direction excited shear mode |
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| WO2022194060A1 (en) * | 2021-03-15 | 2022-09-22 | 偲百创(深圳)科技有限公司 | Acoustic resonator in thickness direction excited shear mode |
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