CN220401721U - Acoustic resonator and filter - Google Patents

Abstract

The application provides an acoustic resonator and filter relates to resonator technical field, including the basement and laminate in proper order in first electrode, piezoelectricity layer and the second electrode on the basement, first electrode, piezoelectricity layer and second electrode form resonance effective area in the range upon range of orientation, and the second electrode is equipped with surface relief structure, and surface relief structure overlaps with resonance effective area part, or surface relief structure sets up in resonance effective area outside. The acoustic impedance mismatch is created by the relief of the surface relief structure in combination with air, thereby reflecting the transverse sound waves. Because the surface relief structure extends along the leading-out direction of the second electrode leading-out part, a plurality of reflection interfaces can be formed by matching with a plurality of relief, so that the transverse sound wave is reflected for a plurality of times, the energy loss is effectively inhibited, and the quality factor of the acoustic resonator is improved.

Description

Acoustic resonator and filter

Technical Field

The present application relates to the technical field of resonators, and in particular, to an acoustic resonator and a filter.

Background

Acoustic resonators can be used to implement signal processing functions in a wide variety of electronic applications. Acoustic resonators typically comprise stacked structures (electrodes/piezoelectric layers/electrodes). The inverse piezoelectric effect causes the acoustic stack to mechanically expand or contract when an electrical signal is applied between the electrodes. As the electrical signal changes over time, the acoustic stack generates acoustic waves that propagate through the acoustic resonator in all directions. The resonance region of the acoustic resonator is subjected to an electric excitation mode by an electric field, and both the resonance region and its peripheral region are subjected to a mode generated by energy scattering in the electric excitation mode, including a transverse mode formed by a transverse acoustic wave excited at the edge of the peripheral region.

The transverse mode generally has a detrimental effect on the performance of the acoustic resonator, and therefore, some acoustic resonators are designed to suppress or mitigate the auxiliary structural features of the transverse mode, such as providing an air bridge on the top electrode to reflect sound waves, but the structure can only initially limit energy leakage, and still have significant energy losses.

Disclosure of Invention

The object of the present application is to provide an acoustic resonator and a filter, which address the above-mentioned drawbacks of the prior art.

In order to achieve the above purpose, the technical solution adopted in the embodiment of the present application is as follows:

in one aspect of the embodiments of the present application, an acoustic resonator is provided, including a substrate, and a first electrode, a piezoelectric layer, and a second electrode sequentially stacked on the substrate, where the first electrode, the piezoelectric layer, and the second electrode form a resonance effective area in a stacking direction, and the second electrode is provided with a surface relief structure along an electrode extending direction, and the surface relief structure partially overlaps the resonance effective area, or the surface relief structure is disposed outside the resonance effective area.

Optionally, the surface relief structure comprises at least one protruding structure and at least one recessed structure arranged along the same direction, and the protruding structures and the recessed structures are staggered.

Optionally, the bump structure is provided with a plurality of, and a plurality of bump structures enclose with the piezoelectric layer to form a plurality of first cavities.

Optionally, the concave structure is spaced apart from and opposite to the piezoelectric layer, and the plurality of first cavities are mutually communicated.

Optionally, a blocking block is disposed on the piezoelectric layer, and the blocking block is disposed between the concave structure and the piezoelectric layer and is used for blocking the plurality of first cavities.

Optionally, the distance between two adjacent protruding structures is equal.

Optionally, the distance from the protruding structure to the substrate surface is greater than the distance from the second electrode corresponding to the resonance effective area to the substrate surface in the vertical direction of the substrate.

Optionally, the distance from the protruding structure to the substrate surface is equal to the distance from the second electrode corresponding to the resonance effective area to the substrate surface along the vertical direction of the substrate.

Optionally, the distance from the protruding structure to the substrate surface is smaller than the distance from the second electrode corresponding to the resonance effective area to the substrate surface along the vertical direction of the substrate.

Alternatively, the cross-sectional shape of the raised structure is trapezoidal.

Optionally, the protruding structure has a first horizontal portion, the recessed structure has a second horizontal portion, and a lateral dimension of the first horizontal portion is greater than a lateral dimension of the second horizontal portion.

Optionally, an acoustic reflection structure is arranged in the first cavity, and the acoustic reflection structure is matched with the shape of the first cavity.

In yet another aspect of embodiments of the present application, a filter is provided that includes an acoustic resonator of any of the above.

The beneficial effects of this application include:

the application provides an acoustic resonator and a filter, including the basement and laminate in proper order first electrode, piezoelectric layer and the second electrode on the basement, first electrode, piezoelectric layer and second electrode form resonance effective area in the range upon range of orientation, and the second electrode is equipped with the surface relief structure along electrode extending direction, and surface relief structure and resonance effective area part overlap, or surface relief structure sets up in resonance effective area outside. The acoustic impedance mismatch is created by the relief of the surface relief structure in combination with air, thereby reflecting the transverse sound waves. Because the surface relief structure extends along the leading-out direction of the second electrode leading-out part, a plurality of reflection interfaces can be formed by matching with a plurality of relief, so that the transverse sound wave is reflected for a plurality of times, the energy loss is effectively inhibited, and the quality factor of the acoustic resonator is improved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered limiting the scope, and that other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic structural diagram of an acoustic resonator according to an embodiment of the present application;

FIG. 2 is a second schematic diagram of an acoustic resonator according to an embodiment of the present disclosure;

FIG. 3 is a third schematic diagram of an acoustic resonator according to an embodiment of the present disclosure;

FIG. 4 is a schematic diagram of an acoustic resonator according to an embodiment of the present disclosure;

FIG. 5 is a schematic diagram of an acoustic resonator according to an embodiment of the present disclosure;

FIG. 6 is a schematic diagram of an acoustic resonator according to an embodiment of the present disclosure;

FIG. 7 is a schematic diagram of an acoustic resonator according to an embodiment of the present disclosure;

FIG. 8 is a schematic diagram of an acoustic resonator according to an embodiment of the present disclosure;

FIG. 9 is a schematic diagram of another acoustic resonator according to an embodiment of the present disclosure;

FIG. 10 is a second schematic diagram of another acoustic resonator according to an embodiment of the present disclosure;

FIG. 11 is a third schematic structural view of yet another acoustic resonator according to an embodiment of the present disclosure;

FIG. 12 is a schematic diagram of an acoustic resonator according to an embodiment of the present disclosure;

FIG. 13 is a second simulation diagram of an acoustic resonator according to an embodiment of the present disclosure;

fig. 14 is a schematic structural diagram of still another acoustic resonator according to an embodiment of the present application;

fig. 15 is a schematic diagram of a preparation state of an acoustic resonator according to an embodiment of the present application;

FIG. 16 is a second schematic diagram of a preparation state of an acoustic resonator according to an embodiment of the present disclosure;

FIG. 17 is a third schematic diagram of a preparation state of an acoustic resonator according to an embodiment of the present disclosure;

FIG. 18 is a schematic diagram showing a preparation state of an acoustic resonator according to an embodiment of the present disclosure;

FIG. 19 is a schematic diagram showing a preparation state of an acoustic resonator according to an embodiment of the present disclosure;

FIG. 20 is a schematic diagram showing a preparation state of an acoustic resonator according to an embodiment of the present disclosure;

FIG. 21 is a schematic diagram of a preparation state of an acoustic resonator according to an embodiment of the present disclosure;

fig. 22 is a schematic diagram illustrating a preparation state of an acoustic resonator according to an embodiment of the present application.

Icon: 110-a substrate; 111-a third groove; 120-a first electrode; 130-a piezoelectric layer; 131-a first surface; 132-a second groove; 140-a second electrode; 141-a second electrode located within the resonant active area; 142-surface relief structure; 143-a bump structure; 1431-a first cavity; 144-a recessed structure; 145-reflection angle; 146-transition; 150-a sacrificial layer; 160-a blocking piece; 170-a second signal terminal; 180-a first signal terminal; 190-a transition layer; 191-fourth grooves; 210-protective layer.

Detailed Description

For the purposes of making the objects, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments. The components of the embodiments of the present application, which are generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the present application, as provided in the accompanying drawings, is not intended to limit the scope of the application, as claimed, but is merely representative of selected embodiments of the application. It should be noted that, in the case of no conflict, the features of the embodiments of the present application may be combined with each other, and the combined embodiments still fall within the protection scope of the present application.

In the description of the present application, it should be noted that, directions or positional relationships indicated by terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., are directions or positional relationships based on those shown in the drawings, or are directions or positional relationships that are conventionally put in use of the product of the application, are merely for convenience of description of the present application and simplification of description, and are not indicative or implying that the apparatus or element to be referred to must have a specific direction, be configured and operated in a specific direction, and therefore should not be construed as limiting the present application. Furthermore, the terms "first," "second," "third," and the like are used merely to distinguish between descriptions and should not be construed as indicating or implying relative importance.

In the description of the present application, it should also be noted that, unless explicitly specified and limited otherwise, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the terms in this application will be understood by those of ordinary skill in the art in a specific context.

In an aspect of the embodiments of the present application, as shown in fig. 1 to 11 and 14, an acoustic resonator is provided, including a substrate 110, and a first electrode 120, a piezoelectric layer 130, and a second electrode 140 sequentially stacked on the substrate 110, wherein the first electrode 120, the piezoelectric layer 130, and the second electrode 140 form a resonance effective area, that is, an operation area of the acoustic resonator, in a stacking direction.

With continued reference to fig. 1 to 11 and 14, the second electrode 140 has a surface relief structure 142 disposed along the extending direction of the second electrode, and the surface relief structure 142 may have a portion located in the effective resonance area, or the surface relief structure 142 may be completely disposed outside the effective resonance area. Therefore, the surface relief structure 142 is matched with air to form a transverse sound reflection structure, and as the surface relief structure 142 is arranged along the extending direction of the second electrode, acoustic impedance mismatch can be formed by means of the relief matching of the surface relief structure 142 and the air, a plurality of reflection interfaces can be formed by matching with a plurality of relief, so that transverse sound waves are reflected for a plurality of times, energy loss is effectively restrained, and the quality factor of the acoustic resonator is improved.

With continued reference to fig. 1 to 11 and fig. 14, the surface relief structure 142 has protruding structures 143 and recessed structures 144 that are alternately (or alternately) arranged along the same direction (e.g., the direction in which the second electrode 140 is led out), wherein the number of protruding structures 143 and recessed structures 144 is at least one. The protruding structures 143 are protruding portions of the surface relief structures, the recessed structures 144 are recessed portions of the surface relief structures 142 (the upper and lower portions are perpendicular to the direction of the substrate 110, the upper portion is the direction in which the surface relief structures 142 are far away from the substrate 110, and the lower portion is the direction in which the surface relief structures 142 are close to the substrate 110), and the protruding structures 143 and the recessed structures 144 are continuous with each other to form the relief of the surface relief structures 142, so that a plurality of reflection interfaces can be formed by matching with a plurality of relief structures, and therefore, the transverse sound waves are reflected for a plurality of times, energy loss is effectively suppressed, and the quality factor of the acoustic resonator is improved.

The first cavity 1431 may be formed between each bump structure 143 and the piezoelectric layer 130 by enclosing, so that the bump structures 143 cooperate with the first cavity 1431 to form an acoustic impedance mismatch, and further form a reflecting surface, so that the leaked transverse sound waves are reflected, and meanwhile, due to the concave structure 144, the second cavity may be formed by the concave structure 144, so that the acoustic impedance mismatch can be formed by cooperation of the second cavity and the concave structure 144, and further form a reflecting surface, so that the leaked transverse sound waves are reflected.

For example, as shown in fig. 1, with the resonance effective area as the center, the transverse sound wave is reflected by the second cavity matching concave structure 144 closest to the resonance effective area, so as to primarily suppress energy loss, and then is secondarily reflected by the first cavity 1431 matching convex structure 143, so that the transverse sound wave can be repeatedly reflected by the surface relief structure, thereby effectively suppressing energy loss and improving the quality factor of the acoustic resonator.

It should be appreciated that, in order to facilitate formation of the surface relief structure 142, this may be achieved by the sacrificial layer 150, in which, as shown in fig. 1, the bump structure 143 is formed across the surface relief structure 142 on the sacrificial layer 150, the recess structure 144 is formed at a portion falling between the sacrificial layer 150, and then the first cavity 1431 is formed by release of the sacrificial layer 150, as shown in fig. 1 to 3 and fig. 5 to 7, for example, each showing a state after the sacrificial layer 150 is previously provided on the piezoelectric layer 130 at a position where the bump structure 143 and the first cavity 1431 are desired to be formed, and then the second electrode 140 is formed, in which the sacrificial layer 150 may be removed by a release process, thereby allowing a space originally occupied by the sacrificial layer 150 as the first cavity 1431, as shown in fig. 4 and 8, to be formed at a position originally occupied by the sacrificial layer 150 after the release of the sacrificial layer 150. Thus, the target position, size, etc. of the first cavity 1431 can be achieved by controlling the sacrificial layer 150. Further, the number of the plural in the present application is at least two, that is, the number may be two or more than two.

Alternatively, as shown in fig. 1 to 8, examples are shown in which the surface relief structure has three convex structures 143 and three concave structures 144, respectively, the three convex structures 143 and the three concave structures 144 alternate with each other, and are linearly arranged in the direction in which the second electrode 140 is drawn out, and thus, when the surface relief structure 142 has other numbers of convex structures 143 and concave structures 144, this arrangement can be referred to.

Alternatively, as shown in fig. 5 to 8, the surface relief structure 142 may be floated with respect to the upper surface of the piezoelectric layer 130, i.e., the recess structure 144 is spaced apart from the piezoelectric layer 130, and adjacent first cavities 1431 may be interconnected by a spaced-apart region between the recess structure 144 and the piezoelectric layer 130.

Alternatively, as shown in fig. 1 to 8, the piezoelectric layer 130 has a first surface 131 facing away from the substrate 110, and the first surface 131 may be concave inward to form a first groove outside the effective resonance area, and the surface relief structure 142 may be located in the first groove, so that by means of sinking the piezoelectric layer 130 to form the first groove, the surface relief structure 142 can effectively reflect the transverse acoustic wave leaked at the piezoelectric layer 130 in the effective resonance area, thereby further suppressing energy loss and improving the quality factor of the acoustic resonator. Of course, in other examples, it may be that the surface relief structure 142 is partially located in the first groove.

Optionally, as shown in fig. 9 to 10, a blocking piece 160 is provided between each concave structure 144 and the piezoelectric layer 130, whereby, on the one hand, two adjacent first cavities 1431 can be blocked by the blocking piece 160, and on the other hand, the surface relief structure 142 can be supported, so that the reliability thereof is improved. Meanwhile, due to the fact that the space is reserved between two adjacent blocking blocks 160, the transverse sound waves can be reflected by utilizing the fact that the blocking blocks 160 and the blocking blocks 160 are different in air material, and then the sound reflection effect is effectively improved.

Alternatively, the blocking blocks 160 are disposed around the overlapping area, as shown in fig. 11, and the blocking blocks 160 are disposed around the overlapping area, so that the transverse sound waves can be effectively reflected in the circumferential direction of the overlapping area by using different materials of air and the blocking blocks 160, and in view of the fact that the blocking blocks 160 are sequentially arranged at intervals apart from the overlapping area, multiple reflections can be performed on the transverse sound waves.

As shown in fig. 11, a first signal terminal 180 and a second signal terminal 170 are further disposed on the piezoelectric layer 130 outside the overlapping region, wherein the first signal terminal 180 may be electrically connected to the second electrode 141 located in the resonance effective region via the surface relief structure 142, and the second signal terminal 170 may be electrically connected to the first electrode 120.

Alternatively, as shown in fig. 3 to 4 and fig. 7 to 8, the first cavity 1431 closest to the resonance effective region may be located at a side wall of the first groove close to the resonance effective region.

Alternatively, as shown in fig. 1 to 8, the distance between any adjacent two of the bump structures 143 may be equal.

Optionally, a transition portion 146 may be further provided between the second electrode 141 and the surface relief structure 142 located in the resonance effective region, the transition portion 146 being stepped along the extending direction of the second electrode 140. As shown in fig. 9 and 10, the transition portion 146 is disposed in a downward step in a direction away from the resonance effective area (i.e., the extending direction of the second electrode 140), and the piezoelectric layer 130 is correspondingly disposed in a downward step, so that a gap is formed between the transition portion 146 and the piezoelectric layer 130, and thus, an reflection angle 145 with mismatched acoustic impedance can be formed at the step in cooperation with external air, and further, a transverse sound wave is reflected, thereby contributing to further improving the reflection effect of the transverse sound wave. As shown in fig. 9, an example in which one reflection angle 145 is provided at a step is shown, and as shown in fig. 10, an example in which two reflection angles 145 are provided at a step is shown.

Alternatively, as shown in fig. 1, 3, 5 and 7, along the vertical direction of the substrate 110, the distance h1 from the protrusion structure 143 to the upper surface of the substrate 110 is smaller than the distance h2 from the second electrode corresponding to the resonance effective area to the upper surface of the substrate 110, where the distance h1 from the protrusion structure 143 to the upper surface of the substrate 110 is: the distance from the top surface of the bump structure 143 (the highest point of the bump structure 143) to the upper surface of the substrate 110 is the second electrode 141 located in the resonance effective area, and therefore, the distance h2 from the second electrode corresponding to the resonance effective area to the upper surface of the substrate 110 is: the distance from the upper surface of the second electrode 141 located in the resonance effective region to the upper surface of the substrate 110, it should be understood that the upper surface of the substrate 110 introduced when the two are compared with each other should be referred to as the same, for example, the flat and non-depressed portions of the upper surface of the substrate 110 in fig. 1. Of course, as shown in fig. 2, 4, 6 and 8, the distance h1 from the bump structure 143 to the surface of the substrate 110 is greater than the distance h2 from the second electrode corresponding to the effective resonance area to the surface of the substrate along the vertical direction of the substrate, where each meaning refers to an example when the ratio of the foregoing two distances is smaller, so that the height of the bump structure 143 is higher than the upper surface of the second electrode 141 located in the effective resonance area, and the surface relief structure 142 can reflect the transverse sound wave at a position higher than the upper surface of the second electrode 141 located in the effective resonance area, which is helpful for further printing energy loss and improving the quality factor. Further, in some examples, the distance of the raised structures 143 from the surface of the substrate 110 in the vertical direction of the substrate is equal to the distance of the corresponding second electrode from the surface of the substrate 110 of the resonance effective area.

Alternatively, as shown in fig. 1 to 8, the cross-sectional shape of the protrusion structure 143 is trapezoidal, and thus, it is possible to have superior stability.

Alternatively, as shown in fig. 1 to 8, the protrusion structure 143 has a first horizontal portion, and the recess structure 144 has a second horizontal portion, and the lateral dimension of the first horizontal portion is greater than the lateral dimension of the second horizontal portion.

Alternatively, as shown in fig. 1 to 4, the surface relief structure 142 is in contact with the bottom surface of the first groove through the recess structure 144, so that support is provided by the recess structure 144.

Optionally, an acoustic reflection structure may be filled in the first cavity 1431, and the acoustic reflection structure is adapted to the shape of the first cavity 1431. The sound reflecting structure may be a single material that is not matched to the acoustic impedance of the bump structure 143, although the sound reflecting structure may be a plurality of materials that are not matched to each other in acoustic impedance so as to form a sound reflecting interface for better reflecting the transverse sound waves.

As shown in fig. 1 to 10, in order to reflect the longitudinal acoustic wave, a third groove 111 may be formed in a concave manner on a surface of the substrate 110, which is close to the piezoelectric layer 130, so that the level formed on the substrate 110 is relatively flat, therefore, the third groove 111 may be filled with the sacrificial layer 150 first, and then an unfilled space is formed in the third groove 111 by releasing the sacrificial layer 150, so that the longitudinal acoustic wave can be reflected as a longitudinal acoustic reflection structure, so as to further improve the quality factor.

As shown in fig. 12, it can be seen from simulation that the acoustic resonator shown in fig. 8 of the present application can basically bring about a Qp (parallel quality factor) improvement of about 10%. Whereas conventional structures generally only bring about a Qp 3.64% improvement.

As shown in fig. 13, it can be seen through simulation that the acoustic resonator shown in fig. 1 and 10 of the present application can also improve the effect of suppressing energy loss compared to the conventional scheme.

Alternatively, as shown in fig. 14, the piezoelectric layer 130 has a first surface 131 facing away from the substrate 110, where the first surface 131 is concavely formed with a second groove 132 at each first cavity 1431, and the second groove 132 communicates with the first cavity 1431 above the first groove, so that, on the basis of the foregoing acoustic reflection effect, the lateral acoustic wave can be reflected by the side wall of the second groove 132, which is helpful for obtaining a better reflection effect.

In addition, as shown in fig. 14, a transition layer 190 is further disposed between the substrate 110 and the first electrode 120, and the material of the transition layer 190 may be gallium nitride, so that the longitudinal acoustic reflection structure may be located on the transition layer 190, for example, in fig. 14, a fourth groove 191 is concavely formed on a surface of a side of the transition layer 190 facing away from the substrate 110, and the longitudinal acoustic reflection structure is formed by using the fourth groove 191.

Alternatively, as shown in fig. 14, a protective layer 210 may also be formed over the second electrode 140, thereby providing protection and improving the reliability of the resonator.

In order to facilitate the understanding of the present application, a method for manufacturing an acoustic resonator of the present application will be described below by way of example with reference to the accompanying drawings.

Taking the acoustic resonator shown in fig. 4 as an example: as shown in fig. 15, a third groove 111 is formed on the substrate 110 by etching, then a sacrificial layer 150 is filled in the third groove 111, and the sacrificial layer 150 is flush with the upper surface of the substrate 110, and the sacrificial layer 150 is used to form an empty third groove 111 after being released later, so as to form a longitudinal acoustic reflection structure. Next, as shown in fig. 16, a metal is formed on the upper surface of the device shown in fig. 15, and then the first electrode 120 is formed after patterning etching. Next, as shown in fig. 17, a piezoelectric layer 130 is formed on the upper surface of the device shown in fig. 16, and the piezoelectric layer 130 is sunk to form a first recess at a position where the first electrode 120 is not present. Next, as shown in fig. 18, a full layer of sacrificial material is formed at the first recess of the piezoelectric layer 130 and then etched, thereby forming a sacrificial layer 150, which sacrificial layer 150 includes three spaced sacrificial blocks as shown in fig. 18. As shown in fig. 19, a metal is deposited on the surface of the device shown in fig. 18 to form a second electrode 140, which forms a surface relief structure 142 at the first recess due to the sacrificial layer 150 therein, and finally, as shown in fig. 4, a first cavity 1431 and an empty third recess 111 are formed by releasing all the sacrificial layer 150.

Taking the acoustic resonator shown in fig. 8 as an example: as shown in fig. 15, a third groove 111 is formed on the substrate 110 by etching, then a sacrificial layer 150 is filled in the third groove 111, and the sacrificial layer 150 is flush with the upper surface of the substrate 110, and the sacrificial layer 150 is used to form an empty third groove 111 after being released later, so as to form a longitudinal acoustic reflection structure. Next, as shown in fig. 16, a metal is formed on the upper surface of the device shown in fig. 15, and then the first electrode 120 is formed after patterning etching. Next, as shown in fig. 17, a piezoelectric layer 130 is formed on the upper surface of the device shown in fig. 16, and the piezoelectric layer 130 is sunk to form a first recess at a position where the first electrode 120 is not present. Next, as shown in fig. 20, an entire sacrificial layer 150 is formed at the first recess of the piezoelectric layer 130. Next, as shown in fig. 21, three spaced sacrificial blocks continue to be formed over the sacrificial layer 150 at the first recess of the device shown in fig. 20. As shown in fig. 22, a metal is deposited on the surface of the device shown in fig. 21 to form a second electrode 140, where the second electrode forms a surface relief structure 142 at the first recess due to the sacrificial layer 150 therein, and finally, as shown in fig. 8, the first cavity 1431 and the empty third recess 111 are formed by releasing all the sacrificial layer 150, and the concave structure 144 of the surface relief structure 142 is made to be spaced apart from the upper surface of the substrate 110.

In yet another aspect of embodiments of the present application, a filter is provided that includes an acoustic resonator of any of the above. By applying the acoustic resonators and connecting the acoustic resonators in a series and/or parallel manner, the performance of the filter is effectively improved.

The foregoing description is only of the preferred embodiments of the present application and is not intended to limit the same, but rather, various modifications and variations may be made by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims (13)

1. The acoustic resonator is characterized by comprising a substrate, and a first electrode, a piezoelectric layer and a second electrode which are sequentially laminated on the substrate, wherein the first electrode, the piezoelectric layer and the second electrode form a resonance effective area in the lamination direction, the second electrode is provided with a surface relief structure along the extending direction of the electrodes, and the surface relief structure is partially overlapped with the resonance effective area or is arranged outside the resonance effective area.

2. The acoustic resonator of claim 1, wherein the surface relief structure comprises at least one raised structure and at least one recessed structure arranged in the same direction, the raised structures being staggered from the recessed structures.

3. The acoustic resonator of claim 2, wherein the bump structure is provided in a plurality, and wherein the bump structure and the piezoelectric layer enclose a plurality of first cavities.

4. An acoustic resonator according to claim 3, wherein the recess structure is spaced apart from the piezoelectric layer, and the plurality of first cavities are in communication with each other.

5. An acoustic resonator according to claim 3, wherein the piezoelectric layer is provided with a blocking block, the blocking block being arranged between the recess structure and the piezoelectric layer, the blocking block being adapted to block a plurality of the first cavities.

6. An acoustic resonator as claimed in any one of claims 2 to 5, wherein the distance between two adjacent raised structures is equal.

7. The acoustic resonator of claim 6, wherein a distance from the raised structure to the substrate surface is greater than a distance from the second electrode corresponding to the resonance effective area to the substrate surface in a vertical direction of the substrate.

8. The acoustic resonator of claim 6, wherein a distance from the raised structure to the substrate surface in a vertical direction of the substrate is equal to a distance from the second electrode corresponding to the resonance effective area to the substrate surface.

9. The acoustic resonator of claim 6, wherein a distance from the raised structure to the substrate surface is less than a distance from the second electrode corresponding to the resonating effective region to the substrate surface in a vertical direction of the substrate.

10. An acoustic resonator as claimed in any one of claims 7 to 9, wherein the cross-sectional shape of the raised structure is trapezoidal.

11. The acoustic resonator of claim 10, wherein the raised structure has a first horizontal portion and the recessed structure has a second horizontal portion, the first horizontal portion having a lateral dimension that is greater than a lateral dimension of the second horizontal portion.

12. An acoustic resonator as claimed in claim 3, characterized in that an acoustic reflecting structure is provided in the first cavity, which acoustic reflecting structure is adapted to the shape of the first cavity.

13. A filter comprising an acoustic resonator as claimed in any one of claims 1 to 12.