CN114006595B

CN114006595B - Bulk acoustic wave resonator and bulk acoustic wave filter

Info

Publication number: CN114006595B
Application number: CN202111635882.5A
Authority: CN
Inventors: 不公告发明人
Original assignee: Shenzhen Newsonic Technologies Co Ltd
Current assignee: Shenzhen Newsonic Technologies Co Ltd
Priority date: 2021-12-30
Filing date: 2021-12-30
Publication date: 2022-03-29
Anticipated expiration: 2041-12-30
Also published as: CN114006595A

Abstract

A bulk acoustic wave resonator and a bulk acoustic wave filter. The bulk acoustic wave resonator includes: a piezoelectric layer; electrode layers on both sides of the piezoelectric layer; and the electrode edge frame structure is positioned at the edge of the electrode layer and positioned on the side of the electrode layer far away from the piezoelectric layer. The electrode edge frame structure comprises a laminated structure which comprises an edge bump layer and a passivation layer which are superposed in the longitudinal direction, wherein the passivation layer is positioned on one side of the edge bump layer far away from the piezoelectric layer; in the transverse direction, the laminated structure comprises a cantilever part and a protruding structure which are connected with each other, the cantilever part is positioned on one side of the protruding structure, which is far away from the middle part of the electrode layer, and a cantilever gap is arranged between the cantilever part and at least one of the piezoelectric layer and the electrode layer. The inner side edge of the edge convex layer is positioned on the electrode layer, and the convex structure is positioned between the inner side edge of the cantilever gap and the first step structure of the passivation layer. The bulk acoustic wave resonator has a higher quality factor.

Description

Bulk acoustic wave resonator and bulk acoustic wave filter

Technical Field

Embodiments of the present disclosure relate to a bulk acoustic wave resonator and a bulk acoustic wave filter.

Background

A bulk acoustic wave Filter (FBAR) generally has a lower electrode, a piezoelectric layer, and an upper electrode sequentially formed on a substrate, thereby forming a resonant structure having piezoelectric characteristics on the substrate. To improve the Insertion Loss (Insertion Loss) performance of the bulk acoustic wave filter, the structure of the FBAR is continuously optimized to improve the quality factor (Q value) and the parallel resonance impedance Rp value of the resonator.

Disclosure of Invention

There is provided in accordance with at least one embodiment of the present disclosure a bulk acoustic wave resonator including: a piezoelectric layer; electrode layers located on both sides of the piezoelectric layer; the electrode edge frame structure is positioned at the edge of the electrode layer and on one side of the electrode layer, which is far away from the piezoelectric layer, wherein the direction perpendicular to the piezoelectric layer is a first direction, and the direction perpendicular to the edge of the electrode layer, on which the electrode edge frame structure is arranged, and parallel to the piezoelectric layer is a second direction; the electrode edge frame structure comprises a laminated structure including an edge bump layer and a passivation layer stacked in the first direction, the passivation layer being located on a side of the edge bump layer remote from the piezoelectric layer; in the second direction, the stacked structure includes a cantilever portion and a protruding structure connected to each other, the cantilever portion is located on one side of the protruding structure far away from the middle of the electrode layer, a cantilever gap is provided between the cantilever portion and at least one of the piezoelectric layer and the electrode layer, in the second direction, an inner side edge of the edge protruding layer is located on an inner side of an edge of the electrode layer, the passivation layer covers the edge protruding layer to form a first step structure at the inner side edge of the edge protruding layer, and the protruding structure is located between the inner side edge of the cantilever gap and the first step structure of the passivation layer.

In some examples, the cantilever portion extends outward beyond an edge of the electrode layer to form the cantilever gap between the cantilever portion and the piezoelectric layer.

In some examples, an outer edge of the edge bump layer is aligned with an edge of the electrode layer in the first direction, and the passivation layer extends outward beyond the edge of the electrode layer to form the cantilever gap between a portion of the passivation layer beyond the edge of the electrode layer and the piezoelectric layer.

In some examples, the edge bump layer and the passivation layer each extend outward beyond an edge of the electrode layer to form the cantilever gap between a portion of the edge bump layer beyond the edge of the electrode layer and the piezoelectric layer.

In some examples, a second step structure is formed between an outer edge and an inner edge of the edge bump layer, such that a first gap is formed between at least a portion of the edge bump layer between the outer edge of the edge bump layer and the second step structure and the electrode layer, the first gap being at least a portion of the cantilever gap.

In some examples, outer edges of the edge protrusion layer and the passivation layer are aligned with edges of the electrode layer in the first direction.

In some examples, the edge protrusion layer and the passivation layer extend outward beyond an edge of the electrode layer such that a portion of the edge protrusion layer beyond the edge of the electrode layer forms a second gap with the piezoelectric layer, the first gap is continuous with the second gap and the second gap is a portion of the cantilever gap.

In some examples, the stacked structure further comprises a dielectric layer between the edge protrusion layer and the electrode layer, the dielectric layer being located at least within the protrusion structure of the stacked structure.

In some examples, the dielectric layer, the edge bump layer, and the passivation layer each extend outward beyond an edge of the electrode layer to form the cantilever gap between a portion of the dielectric layer beyond the edge of the electrode layer and the piezoelectric layer.

In some examples, the edge bump layer and the passivation layer each extend outward beyond an edge of the electrode layer, an outer edge of the dielectric layer being aligned with the edge of the electrode layer in the first direction to form the cantilever gap between a portion of the edge bump layer beyond the edge of the electrode layer and the piezoelectric layer.

In some examples, the passivation layer extends outward beyond an edge of the electrode layer, outer edges of the dielectric layer and the edge bump layer are aligned with the edge of the electrode layer in the first direction to form the cantilever gap between a portion of the passivation layer beyond the edge of the electrode layer and the piezoelectric layer.

In some examples, a second step structure is formed between an outer edge and an inner edge of the edge bump layer, an outer edge of the dielectric layer is aligned with an edge of the electrode layer in the first direction to form a first gap between at least a portion of the edge bump layer between the outer edge of the edge bump layer and the second step structure and the dielectric layer, the first gap being at least a portion of the cantilever gap.

In some examples, the edge protrusion layer and the passivation layer extend outward beyond an edge of the electrode layer to form a second gap between a portion of the edge protrusion layer beyond the edge of the electrode layer and the piezoelectric layer, the second gap being connected to the first gap and the second gap being a portion of the cantilever gap.

In some examples, the dielectric layer is formed with a third step structure inside an edge of the electrode layer to form a first gap between at least a portion of the dielectric layer between an outside edge of the dielectric layer and the third step structure and the electrode layer, the first gap being at least a portion of the cantilever gap.

In some examples, the dielectric layer, the edge protrusion layer, and the passivation layer each extend outward beyond an edge of the electrode layer to form a second gap between a portion of the dielectric layer beyond the edge of the electrode layer and the piezoelectric layer, the second gap being continuous with the first gap and the second gap being a portion of the cantilever gap.

In some examples, the bulk acoustic wave resonator further includes a substrate base plate, the piezoelectric layer and the electrode layers on both sides of the piezoelectric layer constitute at least a part of a piezoelectric resonance layer, the piezoelectric resonance layer is disposed on the substrate base plate, and an acoustic wave reflection structure is disposed between the piezoelectric resonance layer and the substrate base plate.

In some examples, an area where the piezoelectric layer and the electrode layers on both sides of the piezoelectric layer overlap each other is an effective resonance area, and an orthographic projection of the effective resonance area on the substrate falls within an orthographic projection of the acoustic wave reflecting structure on the substrate.

In some examples, an orthographic projection of the cantilever gap on the substrate base is within an orthographic projection of the acoustic wave reflecting structure on the substrate base.

In some examples, the acoustic wave reflecting structure includes a cavity, the bulk acoustic wave resonator further includes a support layer formed on the substrate base, the substrate base and the support layer enclose the cavity, the piezoelectric resonator layer is formed on a side of the cavity away from the substrate base, the electrode layer facing the cavity is a first electrode layer, the electrode layer facing away from the cavity is a second electrode layer, and the electrode edge frame structure is formed on at least one of the first electrode layer and the second electrode layer.

In some examples, the electrode edge frame structure is formed at least a portion of an entire edge of the electrode layer.

In some examples, the planar shape of the electrode layer provided with the electrode edge frame structure is a polygon including M edges, the electrode edge frame structure is provided at M-N edges, N edges of the electrode layer not provided with the electrode edge frame structure are provided with electrode lead-out-side bump stacks, the kind and number of the stacks included in the electrode lead-out-side bump stacks are the same as those of the bump structures, M and N are positive integers, and N is less than M.

In some examples, the edge bump layer in the electrode lead-out side bump lamination and the edge bump layer in the bump structure are connected to each other to form a ring structure.

In some examples, the N edges of the electrode layer where the electrode edge frame structure is not disposed are also disposed with electrode extraction layers electrically connected to the electrode layer.

In some examples, the electrode lead-out layer is also electrically connected to an edge bump layer in the electrode lead-out-side bump laminate.

In some examples, the planar shape of the electrode layer provided with the electrode edge frame structure is a polygon including M edges, the electrode edge frame structure is formed at M-N edges, the bulk acoustic wave resonator further includes electrode extraction layers located at N edges of the electrode layer where the electrode edge frame structure is not provided, the dielectric layer includes via holes therein, the electrode extraction layers are electrically connected to the electrode layer through the via holes in the dielectric layer, M and N are positive integers, and N is less than M.

In some examples, the edge bump layer is a metal layer.

According to at least one embodiment of the present disclosure, there is provided a bulk acoustic wave filter including at least one bulk acoustic wave resonator, where the at least one bulk acoustic wave resonator is any one of the bulk acoustic wave resonators.

Drawings

To more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings of the embodiments will be briefly introduced below, and it is apparent that the drawings in the following description relate only to some embodiments of the present disclosure and are not limiting to the present disclosure.

Figures 1-33 are cross-sectional views of bulk acoustic wave resonators, respectively, according to some embodiments of the present disclosure;

figure 34 is a plan view of a bulk acoustic wave resonator according to some embodiments of the present disclosure;

FIG. 35 is a graph comparing impedance versus frequency for a thin film bulk acoustic resonator having an electrode edge frame structure and an electrode-less edge frame structure;

fig. 36 is a graph of figure of merit versus frequency for a thin film bulk acoustic resonator comparing an electrode edge frame structure and an electrodeless edge frame structure.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present disclosure more apparent, the technical solutions of the embodiments of the present disclosure will be described clearly and completely with reference to the drawings of the embodiments of the present disclosure. It is to be understood that the described embodiments are only a few embodiments of the present disclosure, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the disclosure without any inventive step, are within the scope of protection of the disclosure.

Unless otherwise defined, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this disclosure belongs. The use of "first," "second," and similar terms in this disclosure is not intended to indicate any order, quantity, or importance, but rather is used to distinguish one element from another. The word "comprising" or "comprises", and the like, means that the element or item listed before the word covers the element or item listed after the word and its equivalents, but does not exclude other elements or items. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

In order to improve the Insertion Loss (Insertion Loss) performance of the bulk acoustic wave resonator, the structure of the bulk acoustic wave resonator is continuously optimized to improve the quality factor (Q value) and the parallel resonance impedance Rp value of the resonator. For example, in some bulk acoustic wave resonator designs, a lower electrode, a piezoelectric layer, and an upper electrode are sequentially stacked to form a piezoelectric resonance layer, a tilted cantilever beam structure is disposed at an edge of the upper electrode to form an air gap between the upper electrode and the piezoelectric layer, and the electrode edge tilted structure and the air gap structure can effectively suppress outward propagation of transverse mode acoustic waves, improve a parallel resonance impedance Rp value, reduce energy consumption of the bulk acoustic wave resonator, and improve a Q value. However, this structure is difficult to control the lateral length of the air gap during fabrication and thus difficult to control in terms of improving the Rp and Q values.

At least one embodiment of the present disclosure provides a bulk acoustic wave resonator including: a piezoelectric layer; electrode layers on both sides of the piezoelectric layer; the electrode edge frame structure is positioned at the edge of the electrode layer and on one side of the electrode layer, which is far away from the piezoelectric layer, wherein the direction perpendicular to the piezoelectric layer is a first direction, and the direction perpendicular to the edge of the electrode layer, on which the electrode edge frame structure is arranged, and parallel to the piezoelectric layer is a second direction; the electrode edge frame structure comprises a laminated structure including an edge bump layer and a passivation layer stacked in the first direction, the passivation layer being located on a side of the edge bump layer remote from the piezoelectric layer; in the second direction, the stacked structure includes a cantilever portion and a protruding structure connected to each other, the cantilever portion is located on one side of the protruding structure away from a middle portion of the electrode layer, a gap (cantilever gap) is provided between the cantilever portion and at least one of the piezoelectric layer and the electrode layer, in the second direction, an inner side edge of the edge protruding layer is located on an inner side of an edge of the electrode layer, the passivation layer covers the edge protruding layer to form a first step structure at the inner side edge of the edge protruding layer, and the protruding structure is located between the inner side edge of the gap and the first step structure of the passivation layer. In the bulk acoustic wave resonator according to the embodiment of the disclosure, the electrode edge frame structure is separately formed on the edge portion of the electrode layer, the cantilever portion and the protruding structure in the electrode edge frame structure can generate a region or an interface with changed acoustic wave propagation impedance, and the protruding structure is a laminated structure, so that transverse waves can be better reflected back into the resonator, and energy loss is reduced. In addition, in the embodiment according to the present disclosure, the size of the bump structure having the stacked-layer structure is mainly determined by the size of at least a portion of the edge bump layer, and the edge bump layer formed on the electrode layer may be formed by a patterning method, so that the size thereof can be more precisely controlled, and further the ability of reflecting the transverse wave back into the resonator can be controlled, and the energy loss can be reduced.

To further clarify the structure and corresponding functions and advantages of a bulk acoustic wave resonator according to some embodiments of the present disclosure, a scheme of a bulk acoustic wave resonator according to some embodiments of the present disclosure is described in more detail below with reference to the accompanying drawings.

In the embodiments described below, a Film Bulk Acoustic Resonator (FBAR) is described as an example. However, the embodiments according to the present disclosure are not limited to the thin film bulk acoustic resonator, but may be other kinds of bulk acoustic resonators such as a fixed mount bulk acoustic resonator (BAW-SMR).

Figure 1 is a schematic cross-sectional structure of a thin film bulk acoustic resonator according to some embodiments of the present disclosure. As shown in fig. 1, the thin film bulk acoustic resonator includes a substrate base 100 and a piezoelectric resonance layer formed on the substrate base 100. The piezoelectric resonance layer includes a lower electrode layer 300, a piezoelectric layer 400, and an upper electrode layer 500, which are sequentially stacked in a direction (X direction) perpendicular to the substrate base plate 100. For example, a support layer 200 is disposed between the piezoelectric resonance layer and the substrate base plate 100, and the support layer 200 is disposed near an edge of the piezoelectric resonance layer, thereby defining a cavity 1000 between the piezoelectric resonance layer, the support layer 200, and the substrate base plate 100. The cavity 1000 may be used for acoustic wave reflection between the piezoelectric resonance layer and the substrate base plate 100, and may also be referred to as an acoustic wave reflection structure. For example, the effective area of the piezoelectric resonance layer is an area where the lower electrode layer 300, the piezoelectric layer 400, and the upper electrode layer 500 all overlap each other and further overlap the cavity in a direction perpendicular to the piezoelectric layer 400 (i.e., a direction perpendicular to the substrate base plate 100, the X direction). For example, as shown in fig. 1, a region a indicated with a double arrow is an effective resonance region of the piezoelectric resonance layer. It should be noted that, for simplicity of illustration, the effective resonance region a is omitted in the subsequent cross-sectional views.

As shown in fig. 1, in the thin film bulk acoustic resonator according to some embodiments of the present disclosure, an electrode edge frame structure is provided at an edge of the upper electrode layer 500 and at a side of the upper electrode layer 500 away from the piezoelectric layer 400. The electrode edge frame structure is a laminated structure disposed along at least a partial edge of the upper electrode layer 500, for example, as shown in fig. 1, the laminated structure portions denoted by d1 and d3 on the upper electrode layer 500.

For convenience of description, a direction perpendicular to the piezoelectric layer 400 is set as a first direction X, and a direction perpendicular to an edge of the upper electrode layer 500 where the electrode edge frame structure is disposed (i.e., a left side edge or a right side edge of the upper electrode layer 500 in fig. 1) and parallel to the piezoelectric layer 400 is set as a second direction Y. The electrode edge frame structure comprises an edge bump layer 700 and a passivation layer 800 stacked in the first direction X, the passivation layer 800 being located on a side of the edge bump layer 700 remote from the piezoelectric layer 400; in the second direction Y, the stack structure of the electrode edge frame structure may be further divided into a cantilever portion and a bump structure connected to each other. In this embodiment, the cantilever portion is a portion corresponding to the designation d3, and the projection structure is a portion corresponding to the designation d 1. The cantilever portion d3 is located on a side of the protruding structure d1 away from the middle of the upper electrode layer 500. For example, as shown in fig. 1, in the second direction Y, the cantilever portion d3 is farther from the middle of the upper electrode layer 500 than the convex structure d 1. The cantilever portion d3 extends outside the edge of the upper electrode layer 500 to form a gap 3000 with the piezoelectric layer 400. An inner side edge of the edge protrusion layer 700 (an edge of the edge protrusion layer 700 near the middle of the upper electrode layer 500 in fig. 1) is positioned on the upper electrode layer 500, that is, positioned inside an edge of the upper electrode layer 500, and the passivation layer 800 covers the edge protrusion layer 700 to form a first step structure s1 at the inner side edge of the edge protrusion layer 700. In the second direction Y, the protrusion structure d1 is located between an inner side edge of the gap 3000 and the first step structure s1 of the passivation layer 800.

In order to facilitate description and understanding of the technical solutions of the embodiments of the present disclosure, some of the terms described above will now be explained. Unless otherwise stated, these explanations of terms also apply to other embodiments in the present disclosure. A direction perpendicular to the piezoelectric layer 400 is set to a first direction X, that is, a vertical direction in fig. 1. Note that the direction perpendicular to the piezoelectric layer 400 is a direction perpendicular to a plane in which most of the piezoelectric layer 400 is located, and it is not required that all of the piezoelectric layers 400 are flat and located on the same plane. For example, the direction perpendicular to the piezoelectric layer 400 is substantially the same as the direction perpendicular to the substrate base plate 100. For example, the term "perpendicular" is not limited to a strict perpendicular, and may be deviated from a direction of a strict perpendicular by a certain small angle, for example, within 10 degrees or within 5 degrees. A direction perpendicular to the edge of the electrode layer (for example, the upper electrode layer 500 in fig. 1, but not limited thereto) where the electrode edge frame structure is disposed and parallel to the piezoelectric layer 400 is the second direction Y. Similarly, a direction parallel to the piezoelectric layer 400 here is also a direction parallel to a plane in which most of the piezoelectric layer 400 lies, and may also be a case of being approximately parallel. In addition, the electrode edge frame structure is disposed along an edge of an electrode layer (e.g., the upper electrode layer 500 in fig. 1), and since fig. 1 is a cross-sectional view, the edge of the upper electrode layer 500 on which the electrode edge frame is disposed extends in a direction perpendicular to the paper surface of fig. 1, and thus, the second direction here is the Y direction shown in fig. 1. In the embodiment shown in fig. 1, the electrode edge frame structure includes the edge protrusion layer 700 and the passivation layer 800, however, without other limitations, the passivation layer 800 may extend to other areas on the upper electrode layer 500. For example, as shown in fig. 1, the passivation layer 800 is also distributed in a region between two oppositely disposed edge bump layers 700. Further, with "inner side" in the above-described "inner side edge", it is meant that a side close to the central portions of the piezoelectric layer 400, the lower electrode layer 300, and the upper electrode layer 500 in a direction parallel to the piezoelectric layer is referred to as inner side. Similarly, the side away from the central portions of the piezoelectric layer 400, the lower electrode layer 300, and the upper electrode layer 500 may be referred to as an "outer side". The lateral and medial sides are in relative relationship to one another for the same feature, element, or layer, the meaning of which is clearly understood from the context of the description and the positional relationship of the lateral and medial sides herein will be more clearly seen in the plan view of the subsequent description. For example, the "gap" described above may be an air gap, but other low acoustic velocity materials may be filled therein. The air gap provides better results because of the lowest acoustic velocity of air.

As shown in fig. 1, during the operation of the film bulk acoustic resonator, a transverse wave is generated, and if the transverse wave is transmitted outside the effective resonance area a of the piezoelectric resonance layer, it means a loss of energy, that is, a reduction in the quality factor (Q value) of the resonator, and thus, the performance of a filter composed of a plurality of resonators is deteriorated. In the thin film bulk acoustic resonator according to the embodiment of the present disclosure, the electrode edge frame structure is provided at the edge of the upper electrode layer 500, and therefore, a region or an interface where the acoustic wave propagation impedance changes can be generated at the electrode edge frame structure, and transverse waves can be reflected inside the resonator, thereby reducing energy loss. In the present embodiment, the electrode edge frame structure includes a bump structure and a cantilever portion connected to each other on the upper electrode layer 500, and at least the bump structure is a stacked structure. As shown in fig. 1, the width of the protruding structure d1 is a dimension in the second direction Y. For example, the width of the raised structure d1 has an effect on the reflected acoustic wave, which may be an integer multiple of a half-wavelength of the shear wave propagating in the resonator. In some examples, the width of the raised structure d1 may be 2 to 4 times the half wavelength of the shear wave, for example, may be 3 times. In the case of the above-described multiple, it is possible to prevent a problem that the process is difficult to control due to an excessively small multiple (an excessively small size), and also to avoid a problem that the effective electromechanical coupling coefficient (Keff 2 value) of the resonator is affected by an excessively large multiple and the resonator performance is affected. However, the above-described multiples in the thin film bulk acoustic resonator according to the embodiment of the present disclosure are also not limited to the above-described example multiples. For the cantilever d3 in the electrode edge frame structure, which forms the gap 3000 with the piezoelectric layer, there can be formed a second region or interface where the propagation impedance of the sound wave changes, and the cantilever d3, in cooperation with the protrusion d1 of the stacked structure, can better reflect the leaked transverse wave back into the resonator body. The width of the cantilever d3, i.e., the dimension in the second direction Y, also has an effect on the transverse wave reflection effect, but is not as much as the effect of the above-described convex structure d 1. The combination of the convex structure and the cantilever part has a secondary filtering effect, can reflect sound waves in two stages, and is beneficial to improving quality factors.

The precise control of the width of the raised structure d1 can improve the performance of the film bulk acoustic resonator. In the thin film bulk acoustic resonator according to the embodiment of the present disclosure, the width of the convex structure d1 is mainly affected by the size of the edge convex layer 700, because the size of the edge convex layer 700 also affects the position of the above-mentioned first step structure formed by the passivation layer in the convex structure. In the embodiment of the present disclosure, the edge protrusion layer in the protrusion structure is a layer separately formed on the upper electrode layer 500, and therefore, the size thereof can be better controlled by a patterning process, and therefore, the width of the protrusion structure d1 can also be better controlled, so that the performance of the film bulk acoustic resonator can be improved.

For example, in the embodiment depicted in fig. 1, the edge bump layer 700 has an outer edge that is aligned with an edge of the upper electrode layer 500, and the passivation layer 800 extends outward beyond the edge of the upper electrode layer 500, thereby forming a gap 3000 between the passivation layer 800 and the piezoelectric layer 400. It is to be noted that "alignment" described herein means alignment in a direction (the first direction X) perpendicular to the piezoelectric layer 400, and the alignment is not limited to strict alignment and may have some deviation within a range of process errors. Furthermore, the explanations of "alignment" here also apply to the embodiments to be described below, except where specifically stated.

Figure 2 is a schematic cross-sectional structure diagram of a thin film bulk acoustic resonator, according to further embodiments of the present disclosure. Unlike fig. 1, the electrode edge frame structure is formed on the lower electrode layer 300, that is, at the edge of the lower electrode layer 300 and on the side away from the piezoelectric layer 400. In this embodiment, the same reference numerals denote the same features as those of the embodiment of fig. 1, and in addition, the reference numerals of the edge protrusion layer 700 ', the passivation layer 800 ', and the gap 3000 ' use the same numerical parts with respect to the corresponding features in fig. 1 and are distinguished by a prime symbol to more clearly indicate the corresponding relationship. Based on the above description of fig. 1, it is also clear for the structure of the embodiment shown in fig. 2, for example, the upper electrode layer 500 in the description of the embodiment of fig. 1 may be replaced with the lower electrode layer 300. For example, an electrode edge frame structure provided on the lower electrode layer 300 is located in the cavity 1000. The embodiment shown in fig. 2 can also achieve the same technical effects as the embodiment shown in fig. 1, and details of the specific structure and technical effects are not repeated here.

Figure 3 is a schematic cross-sectional structure diagram of a thin film bulk acoustic resonator according to further embodiments of the present disclosure. Unlike fig. 1, the electrode edge frame structure is formed on the upper electrode layer 500 and the lower electrode layer 300, that is, at the edge of the upper electrode layer 500 and at the side away from the piezoelectric layer 400 and at the edge of the lower electrode layer 300 and at the side away from the piezoelectric layer 400. The same reference numerals are used for the same features in fig. 3 as those in fig. 1 and 2, and the same portions as those in fig. 1 and 2 may refer to the description of the above embodiment, which is not repeated herein.

Figure 4 is a schematic cross-sectional structure diagram of a thin film bulk acoustic resonator, according to further embodiments of the present disclosure. Unlike fig. 1, both the edge bump layer 700 and the passivation layer 800 extend beyond the edge of the upper electrode layer 500, forming a gap 3000 between the edge bump layer 700 and the piezoelectric layer 400. For other parts, reference may be made to the description of the above embodiments, which are not repeated herein.

Fig. 5 and 6 are schematic cross-sectional structures of thin film bulk acoustic resonators according to further embodiments of the present disclosure. Unlike fig. 4, the electrode edge frame structure of fig. 5 is formed on the lower electrode layer 300, and the electrode edge frame structure of fig. 6 is formed on the lower electrode layer 300 and the upper electrode layer 500. Similarly, the reference numerals of the electrode edge frame structure-related layers and gaps on the lower electrode layer 300 are added with "'" to indicate distinction, based on the reference numerals of the electrode edge frame structure-related layers and gaps on the upper electrode layer 500. For other parts, reference may be made to the description of the above embodiments, which are not repeated herein.

Figure 7 is a schematic cross-sectional structure diagram of a thin film bulk acoustic resonator, according to further embodiments of the present disclosure. On the basis of the embodiment shown in fig. 4, the edge protrusion layer 700 in this embodiment is formed with a second step structure s2 between the outer edge and the inner edge thereof (i.e., in the middle portion), and the second step structure s2 raises the portion between the outer edge of the edge protrusion layer 700 and the second step structure s2 with respect to the other portion, thereby forming a gap 4000 between the raised portion of the edge protrusion layer 700 and the upper electrode layer 500. In addition, the outer edges of the edge bump layer 700 and the passivation layer 800 also extend outward beyond the edge of the upper electrode layer 500 in this embodiment, forming a gap 3000 between the portion of the edge bump layer 700 beyond the edge of the upper electrode layer 500 and the piezoelectric layer. As shown in fig. 7, the gap 3000 and the gap 4000 are connected to each other, thereby collectively constituting a gap between the cantilever portion of the electrode edge frame structure and the upper electrode layer 500 and the piezoelectric layer 400. For example, the portion of the cantilever corresponding to the gap 4000 is d2, and the portion of the cantilever corresponding to the gap 3000 is d3, that is, in this embodiment, the cantilever in the electrode edge frame structure includes two portions, d2 and d3, which together serve as the above-mentioned second region or interface of acoustic wave propagation impedance change, and reflect the leaked transverse wave again. Further, in this embodiment, the width (i.e., the dimension in the second direction Y) of the d2 portion of the cantilever portion can be controlled to be relatively small because there is no edge reflection structure for the transverse wave at the portion corresponding to d2 on the surface of the upper electrode layer 500. If the width of the d2 portion is controlled to be relatively small, the area where the transverse wave is not reflected is also relatively small, so that the performance of the resonator can be improved. However, the specific value of the width of the portion d2 in the embodiment of the present disclosure is not limited, and may be set according to the situation. For example, the width of the d2 portion can be controlled to be 0.3-0.5 microns. The function and parameters of the protruding structure d1 in this embodiment can refer to the description of the above embodiment, and the reference to the width of the entire cantilever portion d2 and d3 also can refer to the content of the above embodiment, and will not be described herein again.

Fig. 8 and 9 are schematic cross-sectional structures of thin film bulk acoustic resonators according to further embodiments of the present disclosure. Unlike fig. 7, the electrode edge frame structure of fig. 8 is formed on the lower electrode layer 300, and the electrode edge frame structure of fig. 9 is formed on the lower electrode layer 300 and the upper electrode layer 500. Similarly, the reference numerals of the electrode edge frame structure-related layers and gaps on the lower electrode layer 300 are added with "'" to indicate distinction, based on the reference numerals of the electrode edge frame structure-related layers and gaps on the upper electrode layer 500. For other parts, reference may be made to the description of the above embodiments, which are not repeated herein.

Figure 10 is a cross-sectional structural schematic of a thin film bulk acoustic resonator according to some embodiments of the present disclosure. Unlike fig. 7, the outer edges of the edge protrusion layer 700 and the passivation layer 800 are aligned with the edge of the upper electrode layer 500. Therefore, in the embodiment illustrated in fig. 10, there is no gap between the cantilever portion and the piezoelectric layer 400.

Fig. 11 and 12 are schematic cross-sectional structures of thin film bulk acoustic resonators according to further embodiments of the present disclosure. Unlike fig. 10, the electrode edge frame structure of fig. 11 is formed on the lower electrode layer 300, and the electrode edge frame structure of fig. 12 is formed on the lower electrode layer 300 and the upper electrode layer 500. Similarly, the reference numerals of the electrode edge frame structure-related layers and gaps on the lower electrode layer 300 are added with "'" to indicate distinction, based on the reference numerals of the electrode edge frame structure-related layers and gaps on the upper electrode layer 500. For other parts, reference may be made to the description of the above embodiments, which are not repeated herein.

Figure 13 is a cross-sectional structural schematic of a thin film bulk acoustic resonator according to some embodiments of the present disclosure. As shown in fig. 13, in the thin film bulk acoustic resonators according to the embodiments, a dielectric layer 600 is further included between the edge protrusion layer 700 and the upper electrode layer 500 in the first direction X. In the embodiment shown in fig. 13, the passivation layer 800, the edge bump layer 700, and the dielectric layer 600 all extend outward beyond the edge of the upper electrode layer 500 to form a gap 3000 between the dielectric layer 600 and the piezoelectric layer 400. In this embodiment, the cantilever portion d3 and the bump structure d1 each include three layers of the passivation layer 800, the edge bump layer 700, and the dielectric layer 600. Further, in fig. 13, an upper electrode lead-out layer 900 for electrical connection with the upper electrode layer 500 is further provided on the opposite side of the upper electrode layer 500 where the electrode edge frame structure is formed. For example, the dielectric layer 600 includes a via 2000 at this position, and the upper electrode lead-out layer 900 is electrically connected to the upper electrode layer 500 through the via 2000 in the dielectric layer 600. As for the planar positional relationship of the upper electrode lead-out layer 900, description will be made later with reference to a plan view.

According to the above-described embodiments, the width of the bump structure (the dimension in the second direction Y) has a large influence on the performance of the thin film bulk acoustic resonator, and the width of the bump structure is determined by the width of the edge bump layer. Therefore, the precise control of the size of the edge bump layer is beneficial to the performance improvement of the film bulk acoustic resonator. In this embodiment, through the introduction of the dielectric layer 600, on one hand, the thickness of the electrode edge frame structure can be increased to improve the acoustic wave reflection performance. For example, the total thickness of the bump structure can be adjusted by controlling the thickness of the dielectric layer 600, so that the quality factor of the resonator is improved without affecting the bandwidth performance of the resonator. On the other hand, the introduction of the dielectric layer 600 can also help in the definition of the boundary of the edge protrusion layer 700, so that the size of the edge protrusion layer 700 can be more precisely controlled. For example, for the patterning process of the edge protrusion layer 700, a lift-off (lift-off) method or an etching method may be selected. Of these two methods, the etching method is more advantageous for the control of the width dimension of the edge protrusion layer 700 and the edge profile (e.g., perpendicularity) of the edge protrusion layer 700. However, if the material for forming the edge protrusion layer 700 is directly deposited on the upper electrode layer 500 and then patterned by photolithography and etching, the thickness of the upper electrode layer 500 may be affected during the etching process. In order to ensure the performance of the film bulk acoustic resonator, the thickness of the electrode layer generally needs to be controlled within +/-2nm, which is very high in requirement on an etching process, expensive in process and difficult to control accurately. In this embodiment, the dielectric layer 600 is formed between the edge protrusion layer 700 and the upper electrode layer 500, and the dielectric layer 600 may serve as a stop layer for etching the edge protrusion layer, so that the upper electrode layer 500 is not affected when the edge protrusion layer 700 is etched. In addition, in the presence of the dielectric layer 600, the flexibility of optimizing the patterning process of the edge protrusion layer 700 is higher, and the control precision of the width dimension of the edge protrusion layer 700 can be further improved, so that the performance of the thin film bulk acoustic resonator is further improved. As described above, with the thin film bulk acoustic resonator of this embodiment, in addition to the technical effects that can be achieved in the above-described embodiment including the two-layer structure, it is possible to have the above-described further technical advantages: the introduction of the dielectric layer 600 can not only enhance the performance improvement provided by the electrode edge frame structure itself, but can also provide further performance improvements due to the relationship with other parts of the resonator, such as the upper electrode layer.

Fig. 14 and 15 are schematic cross-sectional structures of thin film bulk acoustic resonators according to further embodiments of the present disclosure. Unlike fig. 13, the electrode edge frame structure of fig. 14 is formed on the lower electrode layer 300, and the electrode edge frame structure of fig. 15 is formed on the lower electrode layer 300 and the upper electrode layer 500. Similarly, the reference numerals of the electrode edge frame structure-related layers and gaps on the lower electrode layer 300 are added with "'" to indicate distinction, based on the reference numerals of the electrode edge frame structure-related layers and gaps on the upper electrode layer 500. In addition, the lower electrode layer 300 may also be provided with a lower electrode lead-out layer 900'. For other parts, reference may be made to the description of the above embodiments, which are not repeated herein.

Figure 16 is a cross-sectional structural schematic of a thin film bulk acoustic resonator according to some embodiments of the present disclosure. Unlike fig. 13, the outer edges of the dielectric layer 600 in the embodiment shown in fig. 16 are aligned with the edges of the upper electrode layer 500. In this embodiment, the edge bump layer 700 and the passivation layer 800 extend outward beyond the edge of the upper electrode layer 500 to form a gap 3000 between the edge bump layer 700 and the piezoelectric layer 400. In the embodiment shown in fig. 16, the cantilever portion d3 includes a passivation layer 800 and an edge bump layer 700, and the bump structure d1 includes the passivation layer 800, the edge bump layer 700 and the dielectric layer 600.

Fig. 17 and 18 are schematic cross-sectional structures of thin film bulk acoustic resonators according to further embodiments of the present disclosure. Unlike fig. 16, the electrode edge frame structure in fig. 17 is formed on the lower electrode layer 300, and the electrode edge frame structure in fig. 18 is formed on the lower electrode layer 300 and the upper electrode layer 500. Similarly, the reference numerals of the electrode edge frame structure-related layers and gaps on the lower electrode layer 300 are added with "'" to indicate distinction, based on the reference numerals of the electrode edge frame structure-related layers and gaps on the upper electrode layer 500. In addition, the lower electrode layer 300 may also be provided with a lower electrode lead-out layer 900'. For other parts, reference may be made to the description of the above embodiments, which are not repeated herein.

Figure 19 is a cross-sectional structural schematic of a thin film bulk acoustic resonator, according to some embodiments of the present disclosure. Unlike fig. 16, the passivation layer 800 extends outward beyond the edge of the upper electrode layer 500, and the outer edges of the edge bump layer 700 and the dielectric layer 600 are aligned with the edge of the upper electrode layer 500, thereby forming a gap 3000 between the passivation layer 800 and the piezoelectric layer 400. In this embodiment, the cantilever portion d3 includes a passivation layer 800, and the bump structure d1 includes the passivation layer 800, the edge bump layer 700, and the dielectric layer 600.

Fig. 20 and 21 are schematic cross-sectional structures of thin film bulk acoustic resonators according to further embodiments of the present disclosure. Unlike fig. 19, the electrode edge frame structure of fig. 20 is formed on the lower electrode layer 300, and the electrode edge frame structure of fig. 21 is formed on the lower electrode layer 300 and the upper electrode layer 500. Similarly, the reference numerals of the electrode edge frame structure-related layers and gaps on the lower electrode layer 300 are added with "'" to indicate distinction, based on the reference numerals of the electrode edge frame structure-related layers and gaps on the upper electrode layer 500. In addition, the lower electrode layer 300 may also be provided with a lower electrode lead-out layer 900'. For other parts, reference may be made to the description of the above embodiments, which are not repeated herein.

Figure 22 is a cross-sectional structural schematic of a thin film bulk acoustic resonator according to some embodiments of the present disclosure. Unlike the embodiment shown in fig. 16, the second step structure s2 is formed between the outer edge and the inner edge of the edge protrusion layer 700 in fig. 22. That is, the edge bump layer 700 forms a raised structure between the outer edge of the edge bump layer 700 and the second step structure s2, thereby forming a gap 4000 between at least a portion of the raised portion of the edge bump layer 700 and the underlying upper electrode layer 500, and more particularly, the underlying dielectric layer 600. In addition, the passivation layer 800 and the edge bump layer 700 of this embodiment also extend outward beyond the edge of the upper electrode layer 500, such that a gap 3000 is formed between the edge bump layer 700 and the piezoelectric layer 400. The gap 3000 and the gap 4000 are connected to each other, forming a gap between the cantilever portions b2 and b3 and the upper electrode layer 500 (or the dielectric layer 600) and the piezoelectric layer 400. In this embodiment, the cantilever portions d2 and d3 include a passivation layer 800 and an edge bump layer 700, and the bump structure d1 includes the passivation layer 800, the edge bump layer 700 and the dielectric layer 600.

Fig. 23 and 24 are schematic cross-sectional structures of thin film bulk acoustic resonators according to further embodiments of the present disclosure. Unlike fig. 22, the electrode edge frame structure in fig. 23 is formed on the lower electrode layer 300, and the electrode edge frame structure in fig. 24 is formed on the lower electrode layer 300 and the upper electrode layer 500. Similarly, the reference numerals of the electrode edge frame structure-related layers and gaps on the lower electrode layer 300 are added with "'" to indicate distinction, based on the reference numerals of the electrode edge frame structure-related layers and gaps on the upper electrode layer 500. In addition, the lower electrode layer 300 may also be provided with a lower electrode lead-out layer 900'. For other parts, reference may be made to the description of the above embodiments, which are not repeated herein.

Figure 25 is a cross-sectional structural schematic of a thin film bulk acoustic resonator, according to some embodiments of the present disclosure. Unlike the embodiment shown in fig. 22, the outer edges of the passivation layer 800 and the edge protrusion layer 700 are aligned with the edge of the upper electrode layer 500, and thus, the gap 3000 in fig. 22 does not exist.

Fig. 26 and 27 are schematic cross-sectional structures of thin film bulk acoustic resonators according to further embodiments of the present disclosure. Unlike fig. 25, the electrode edge frame structure in fig. 26 is formed on the lower electrode layer 300, and the electrode edge frame structure in fig. 27 is formed on the lower electrode layer 300 and the upper electrode layer 500. Similarly, the reference numerals of the electrode edge frame structure-related layers and gaps on the lower electrode layer 300 are added with "'" to indicate distinction, based on the reference numerals of the electrode edge frame structure-related layers and gaps on the upper electrode layer 500. In addition, the lower electrode layer 300 may also be provided with a lower electrode lead-out layer 900'. For other parts, reference may be made to the description of the above embodiments, which are not repeated herein.

Figure 28 is a cross-sectional structural schematic of a thin film bulk acoustic resonator according to some embodiments of the present disclosure. Unlike the embodiment shown in fig. 13, the dielectric layer 600 is formed with the third step structure s3 inside the edge of the upper electrode layer 500, and the dielectric layer 600 is formed in a raised structure at a portion between the outer edge thereof and the third step structure s3, thereby forming a gap 4000 between a portion of the dielectric layer 600 and the upper electrode layer 500. In addition, the passivation layer 800, the edge bump layer 700, and the dielectric layer 600 all extend outward beyond the edge of the upper electrode layer 500, forming a gap 3000 between another portion of the dielectric layer 600 and the piezoelectric layer 400. The gap 3000 and the gap 4000 are connected to each other, together constituting a gap between the cantilever portions d2 and d3 and the upper electrode layer 500 and the piezoelectric layer 400.

Fig. 29 and 30 are schematic cross-sectional structures of thin film bulk acoustic resonators according to further embodiments of the present disclosure. Unlike fig. 28, the electrode edge frame structure in fig. 29 is formed on the lower electrode layer 300, and the electrode edge frame structure in fig. 30 is formed on the lower electrode layer 300 and the upper electrode layer 500. Similarly, the reference numerals of the electrode edge frame structure-related layers and gaps on the lower electrode layer 300 are added with "'" to indicate distinction, based on the reference numerals of the electrode edge frame structure-related layers and gaps on the upper electrode layer 500. In addition, the lower electrode layer 300 may also be provided with a lower electrode lead-out layer 900'. For other parts, reference may be made to the description of the above embodiments, which are not repeated herein.

Figure 31 is a cross-sectional structural schematic of a thin film bulk acoustic resonator according to some embodiments of the present disclosure. Unlike the embodiment shown in fig. 28, the outer edges of the passivation layer 800, the edge protrusion layer 700, and the dielectric layer 600 are aligned with the edge of the upper electrode layer 500, and thus, the gap 3000 in fig. 28 does not exist.

Fig. 32 and 33 are schematic cross-sectional structures of thin film bulk acoustic resonators according to further embodiments of the present disclosure. Unlike fig. 31, the electrode edge frame structure in fig. 32 is formed on the lower electrode layer 300, and the electrode edge frame structure in fig. 33 is formed on the lower electrode layer 300 and the upper electrode layer 500. Similarly, the reference numerals of the electrode edge frame structure-related layers and gaps on the lower electrode layer 300 are added with "'" to indicate distinction, based on the reference numerals of the electrode edge frame structure-related layers and gaps on the upper electrode layer 500. In addition, the lower electrode layer 300 may also be provided with a lower electrode lead-out layer 900'. For other parts, reference may be made to the description of the above embodiments, which are not repeated herein.

Fig. 34 is a schematic plan view of the surface of the upper electrode layer in the thin film bulk acoustic resonator according to some embodiments of the present disclosure. It should be noted that the cross-sectional view of the embodiment shown in fig. 1 to 12 is a cross-sectional view taken along a folding line AA ', and the cross-sectional view of the embodiment shown in fig. 15 to 33 is a cross-sectional view taken along a folding line BB'. Where the fold line passes through the electrode edge frame structure, it is substantially perpendicular to the edge of the corresponding electrode layer, so that the cross-sectional structure of the electrode edge frame structure may be better reflected. For example, the portion of the fold line passing through the electrode edge frame structure extends in the second direction Y described above. As shown in fig. 34, the piezoelectric resonance layer of the film bulk acoustic resonator is, for example, an irregular pentagon, in which at least one side needs to be provided with an upper electrode lead-out metal layer, so as to electrically connect the upper electrode to an external input or control device. For example, the electrode edge frame structure 5000 in fig. 34 is provided at four edges of the upper electrode of a pentagon. The electrode edge frame structure 5000 herein may include any of the electrode edge frame structures described in the above embodiments, for example, which includes a projection structure and a cantilever portion. In addition, this portion also includes a gap formed between the cantilever portion and the piezoelectric layer and/or the upper electrode. As shown in fig. 34, the electrode edge frame structure is provided at four edges of the upper electrode layer. On one edge where the electrode lead-out metal layer is disposed, the above-described electrode edge frame structure is not disposed, but the edge protrusion layer 700 as described above is also disposed at the edge, and thus, a protrusion structure similar to that in the electrode edge frame structure disposed at the other edge is also disposed at the edge, which may include the edge protrusion layer 700 and the passivation layer 800; or may further include a dielectric layer 600. That is, at the edge where the electrode lead-out structure is provided, the electrode lead-out side bump laminate 6000 is provided on the upper electrode, the cross-sectional structure of the electrode lead-out side bump laminate 6000 being the same as that of the bump structure of the electrode edge frame structure. For example, the electrode lead-out side bump laminate 6000 includes the same kinds and number of layers as those included in the bump structure of the electrode edge frame structure. In addition, although the above-described embodiments have been described taking an example in which the electrode lead-out metal layer is provided at one edge in a pentagon shape, embodiments according to the present disclosure are not limited thereto, the planar shape of the electrode layer may also be other polygonal shapes, and the number of edges at which the electrode lead-out metal layer is provided may also be two or more.

As can be seen in conjunction with fig. 15 and 34, the upper electrode lead-out layer 900 is electrically connected to the upper electrode layer through the via 2000 in the dielectric layer 600. Note that, in the case where a dielectric layer is present on the electrode lead-out side, the upper electrode lead-out layer 900 needs to be connected through a via hole in the dielectric layer 600, as shown in fig. 34. However, without the dielectric layer 600, the presence of the via 2000 is also correspondingly not required. Referring to fig. 13 and 34 in combination, the edge protrusion layer 700 in the electrode lead-out side protrusion stack 6000 and the edge protrusion layer 700 in the protrusion structure may be connected to each other to form a ring structure.

Although not shown in the drawings, the lower electrode layer may be provided with a lower electrode lead-out metal layer for electrode lead-out. For example, the lower electrode lead-out metal layer and the upper electrode lead-out metal layer may be provided at different edges of the piezoelectric resonance layer, for example, at edges opposite to each other. In addition, one side of the lower electrode layer may have various structures corresponding to one side of the upper electrode layer, which are not described herein.

For example, in the above-described embodiments, the upper electrode lead-out layer 900 disposed on the electrode lead-out side may be electrically connected to both the edge protrusion layer 700 and the upper electrode layer 500. In the case where the electrode edge frame structure is disposed on the lower electrode layer 300, the lower electrode lead-out layer 900 'may be connected to both the edge protrusion layer 700' and the lower electrode layer 300.

The material of each layer in the thin film bulk acoustic resonator in the embodiments of the present disclosure is not particularly limited. For example, the edge protrusion layer 700 and the upper electrode lead-out layer 900 in the above embodiments may be metal layers, for example, may be formed using a material forming an electrode, but the embodiment of the present disclosure is not particularly limited thereto. The dielectric layer 600 and the passivation layer 800 may be made of an insulating material such as aluminum nitride, silicon oxide, silicon oxynitride, etc., and the materials of the dielectric layer 600 and the passivation layer 800 may be the same or may be different. In addition, as the material of each layer in the piezoelectric resonance layer, and the material of the substrate base and the support layer, any suitable material in the conventional art can be used, and is not particularly limited herein.

To better illustrate the improvement in performance of the bulk acoustic wave resonator in the embodiment of the present disclosure, a comparative test was performed using the thin film bulk acoustic resonator having the electrode edge frame structure and the thin film bulk acoustic resonator having the electrode edge frame structure of the embodiment shown in fig. 25 described above. Fig. 35 is a graph comparing impedance of the thin film bulk acoustic resonator having the electrode edge frame structure and the electrode-less edge frame structure with frequency, and fig. 36 is a graph comparing quality factors of the thin film bulk acoustic resonator having the electrode edge frame structure and the electrode-less edge frame structure with frequency. As can be seen from fig. 35, due to the introduction of the electrode edge frame structure described in the embodiment of the present disclosure, the parallel resonant impedance Rp of the thin film bulk acoustic resonator is greatly increased, so that a lower Insertion Loss (Insertion Loss) is possible, which is beneficial to improving the filtering performance. As can be seen from fig. 36, due to the introduction of the electrode edge frame structure described in the embodiment of the present disclosure, the quality factor (Q) of the thin film bulk acoustic resonator is greatly improved, so that a lower Insertion Loss (Insertion Loss) is possible, which is beneficial to the improvement of the filtering performance. The film bulk acoustic resonators of other embodiments of the present disclosure also have similar technical effects, and are not described in detail herein.

Although the thin film bulk acoustic resonator is used as an example in the above embodiments, the embodiments of the present disclosure may be applied to other bulk acoustic resonators. It can also be used for example for the fixed mounting of a bulk acoustic wave resonator (BAW-SMR). In the case of the BAW-SMR, since the acoustic wave reflection structure provided below the piezoelectric resonance layer is not a cavity but a bragg reflection layer, the electrode edge frame structure may be provided only on the upper electrode layer. Therefore, providing the electrode edge frame structure on the electrode layer in the embodiments of the present disclosure means providing the structure on the electrode layer having the space where the electrode edge frame structure is provided.

Furthermore, some embodiments according to the present disclosure also provide a bulk acoustic wave filter, for example, the bulk acoustic wave filter includes at least one bulk acoustic wave resonator, and the at least one bulk acoustic wave resonator may be the bulk acoustic wave resonator described in any of the embodiments above. Since the bulk acoustic wave filter according to the embodiment of the present disclosure includes at least one bulk acoustic wave resonator as described above, there are also corresponding advantageous technical effects, which are not described herein again.

The following points need to be explained:

(1) in the drawings of the embodiments of the present disclosure, only the structures related to the embodiments of the present disclosure are referred to, and other structures may refer to general designs.

(2) Features of the disclosure in the same embodiment and in different embodiments may be combined with each other without conflict.

The above is only a specific embodiment of the present disclosure, but the scope of the present disclosure is not limited thereto, and any person skilled in the art can easily conceive of changes or substitutions within the technical scope of the present disclosure, and shall be covered by the scope of the present disclosure. Therefore, the protection scope of the present disclosure shall be subject to the protection scope of the claims.

Claims

1. A bulk acoustic wave resonator comprising:

a piezoelectric layer;

electrode layers located on both sides of the piezoelectric layer;

an electrode edge frame structure located at an edge of the electrode layer and at a side of the electrode layer remote from the piezoelectric layer,

wherein a direction perpendicular to the piezoelectric layer is a first direction, and a direction perpendicular to an edge of the electrode layer where the electrode edge frame structure is provided and parallel to the piezoelectric layer is a second direction; the electrode edge frame structure comprises a laminated structure including an edge bump layer and a passivation layer stacked in the first direction, the passivation layer being located on a side of the edge bump layer remote from the piezoelectric layer; in the second direction, the laminated structure comprises a cantilever part and a convex structure which are connected with each other, the cantilever part is positioned on one side of the convex structure far away from the middle part of the electrode layer,

a cantilever gap is provided between the cantilever portion and at least one of the piezoelectric layer and the electrode layer,

in the second direction, an inner side edge of the edge protrusion layer is located inside an edge of the electrode layer, and the passivation layer covers the edge protrusion layer to form a first step structure at the inner side edge of the edge protrusion layer, the protrusion structure being located between the inner side edge of the cantilever gap and the first step structure of the passivation layer,

a second step structure is formed between the outer edge and the inner edge of the edge bump layer, so that a first gap is formed between at least one part of the edge bump layer, which is located between the outer edge of the edge bump layer and the second step structure, and the electrode layer, wherein the first gap is at least one part of the cantilever gap,

the edge bump layer and the passivation layer extend outward beyond the edge of the electrode layer such that a second gap is formed between a portion of the edge bump layer beyond the edge of the electrode layer and the piezoelectric layer, the first gap being connected to the second gap and the second gap being a portion of the cantilever gap.

2. The bulk acoustic wave resonator according to claim 1, wherein the stacked structure further comprises a dielectric layer between the edge bump layer and the electrode layer, the dielectric layer being located at least within the bump structure of the stacked structure.

3. The bulk acoustic wave resonator according to claim 2, wherein an outer edge of the dielectric layer is aligned with an edge of the electrode layer in the first direction to form the first gap between the dielectric layer and at least a portion of the edge bump layer between the outer edge of the edge bump layer and the second step structure.

4. The bulk acoustic wave resonator according to claim 2, wherein the dielectric layer is formed with a third step structure inside an edge of the electrode layer to form the first gap between the electrode layer and at least a portion of the dielectric layer between an outer edge of the dielectric layer and the third step structure.

5. The bulk acoustic wave resonator according to claim 4, wherein the dielectric layer, the edge bump layer and the passivation layer each extend outwardly beyond an edge of the electrode layer to form the second gap between a portion of the dielectric layer beyond the edge of the electrode layer and the piezoelectric layer.

6. The bulk acoustic wave resonator according to any one of claims 1 to 5, further comprising a substrate base plate, the piezoelectric layer and the electrode layers on both sides of the piezoelectric layer constituting at least a part of a piezoelectric resonance layer, the piezoelectric resonance layer being provided on the substrate base plate, and an acoustic wave reflecting structure being provided between the piezoelectric resonance layer and the substrate base plate.

7. The bulk acoustic wave resonator according to claim 6, wherein a region where the piezoelectric layer and the electrode layers on both sides of the piezoelectric layer overlap with each other is an effective resonance region, and an orthographic projection of the effective resonance region on the substrate falls within an orthographic projection of the acoustic wave reflecting structure on the substrate.

8. The bulk acoustic wave resonator according to claim 7, wherein an orthographic projection of the cantilever gap on the substrate base is within an orthographic projection of the acoustic wave reflecting structure on the substrate base.

9. The bulk acoustic wave resonator according to claim 6, wherein the acoustic wave reflecting structure comprises a cavity, the bulk acoustic wave resonator further comprises a support layer formed on the substrate base, the substrate base and the support layer enclose the cavity, the piezoelectric resonator layer is formed on a side of the cavity away from the substrate base, the electrode layer facing the cavity is a first electrode layer, the electrode layer facing away from the cavity is a second electrode layer, and the electrode edge frame structure is formed on at least one of the first electrode layer and the second electrode layer.

10. The bulk acoustic wave resonator according to any one of claims 1 to 5, wherein the electrode edge frame structure is formed at least a part of the entire edge of the electrode layer.

11. The bulk acoustic wave resonator according to any one of claims 1 to 5, wherein the planar shape of the electrode layer provided with the electrode edge frame structure is a polygon including M edges, the electrode edge frame structure is provided at M-N edges, and N edges of the electrode layer not provided with the electrode edge frame structure are provided with electrode-lead-out-side bump stacks including the same kind and number of stacks as those of the bump structures, M and N are positive integers, and N is smaller than M.

12. The bulk acoustic wave resonator according to claim 11, wherein the edge bump layer in the electrode lead-out side bump stack and the edge bump layer in the bump structure are connected to each other to form a ring structure.

13. The bulk acoustic wave resonator according to claim 12, wherein an electrode extraction layer is further provided at the N edges of the electrode layer where the electrode edge frame structure is not provided, the electrode extraction layer being electrically connected to the electrode layer.

14. The bulk acoustic wave resonator according to claim 13, wherein the electrode lead-out layer is further electrically connected to an edge bump layer in the electrode lead-out-side bump laminate layer.

15. The bulk acoustic wave resonator according to claim 2, wherein a planar shape of the electrode layer provided with the electrode edge frame structure is a polygon including M edges, the electrode edge frame structure being formed at the M-N edges,

the bulk acoustic wave resonator further comprises electrode leading-out layers located at N edges of the electrode layer, where the electrode edge frame structures are not arranged, the dielectric layer comprises through holes, the electrode leading-out layers are electrically connected with the electrode layer through the through holes in the dielectric layer, M and N are positive integers, and N is smaller than M.

16. The bulk acoustic wave resonator according to any one of claims 1 to 5, wherein the edge bump layer is a metal layer.

17. A bulk acoustic wave filter comprising at least one bulk acoustic wave resonator, the at least one bulk acoustic wave resonator being a bulk acoustic wave resonator according to any one of claims 1-16.