WO2022062912A1

WO2022062912A1 - Bulk acoustic wave resonator having acoustic resistance layer, and assembly thereof and manufacturing method therefor, filter, and electronic device

Info

Publication number: WO2022062912A1
Application number: PCT/CN2021/117485
Authority: WO
Inventors: 庞慰; 班圣光; 徐洋; 杨清瑞; 张孟伦
Original assignee: 诺思(天津)微系统有限责任公司
Priority date: 2020-09-22
Filing date: 2021-09-09
Publication date: 2022-03-31
Also published as: CN114257204A

Abstract

The present disclosure relates to a bulk acoustic wave resonator, comprising: a substrate; an acoustic mirror; a bottom electrode; a piezoelectric layer; and a top electrode. The overlapping region of the top electrode, the piezoelectric layer, and the bottom electrode in the thickness direction of the resonator constitutes an effective region of the resonator; the piezoelectric layer comprises a first layer and a second layer; an acoustic resistance layer is provided between the first layer and the second layer; the second layer is located above the first layer; the inner edge of the acoustic resistance layer is located at the inner side of the boundary of the acoustic mirror in a horizontal direction; the acoustic resistance of the acoustic resistance layer is different from the acoustic resistance of the piezoelectric layer; and the resonator further comprises a channel or an opening for communicating the acoustic resistance layer with the outside. The present disclosure further relates to a bulk acoustic wave resonator assembly, a method for manufacturing a bulk acoustic wave resonator, a filter, and an electronic device.

Description

Bulk acoustic wave resonator with acoustic resistance layer and its assembly and manufacturing method, filter and electronic device

technical field

Embodiments of the present disclosure relate to the field of semiconductors, and in particular, to a bulk acoustic wave resonator and components thereof, a method of manufacturing a bulk acoustic wave resonator, a filter, and an electronic device.

Background technique

With the increasing development of 5G communication technology, the requirements for data transmission rate are getting higher and higher. Corresponding to the data transmission rate is the high utilization rate of spectrum resources and the complexity of spectrum. The complexity of the communication protocol puts forward strict requirements for various performances of the radio frequency system. In the radio frequency front-end module, the radio frequency filter plays a crucial role, which can filter out out-of-band interference and noise to meet the requirements of the radio frequency system and the Communication protocol requirements for signal-to-noise ratio.

Traditional RF filters are limited by structure and performance and cannot meet the requirements of high-frequency communication. As a new type of MEMS device, thin film bulk acoustic resonator (FBAR) has the advantages of small size, light weight, low insertion loss, high frequency bandwidth and high quality factor. It has become one of the research hotspots in the field of communication.

The series resonators and parallel resonators of the prior art filters work together to form the filter passband characteristics. By setting the series resonance frequencies of the series resonators to be different from each other and the variation of the electromechanical coupling coefficient Kt ² of the series resonators, the roll-off characteristic on the right side of the passband of the filter can be effectively improved. It is easy to achieve good roll-off characteristics by applying a small Kt ² resonator to the filter, but once the design indicators (bandwidth, insertion loss, out-of-band rejection, etc.) are determined, the Kt ² of the resonator is basically determined, so that the filter bandwidth and filter The good roll-off characteristics of the resonator are contradictory. It is difficult to achieve good roll-off characteristics in the design of wide-bandwidth filters under the conventional architecture. ^The change of Kt2 of the 50Ohm resonator is only about ±0.5%, and the improvement of the filter roll-off characteristic is limited. Therefore, releasing the restriction of the degree of freedom of Kt ² between each resonator is beneficial to improve the roll-off performance of the entire filter.

In addition, the structural main body of the thin film bulk acoustic wave resonator is a "sandwich" structure composed of electrode-piezoelectric film-electrode, that is, a piezoelectric material is sandwiched between two metal electrode layers. By inputting a sinusoidal signal between two electrodes, the FBAR uses the inverse piezoelectric effect to convert the input electrical signal into mechanical resonance, and then uses the piezoelectric effect to convert the mechanical resonance into an electrical signal output. The film bulk acoustic wave resonator mainly uses the longitudinal piezoelectric coefficient of the piezoelectric film to generate the piezoelectric effect, so its main working mode is the longitudinal wave mode in the thickness direction, that is, the sound wave of the bulk acoustic wave resonator is mainly in the film body of the resonator, and the main working mode is the longitudinal wave mode in the thickness direction. The vibration direction is in the vertical direction. However, due to the existence of a boundary, there will be Lamb waves that are not perpendicular to the piezoelectric film layer at the boundary. At this time, the lateral Lamb wave will leak out from the lateral direction of the piezoelectric film layer, resulting in acoustic loss, thus making the Q value of the resonator. decrease. There is also a need in the prior art to further reduce lateral Lamb wave leakage.

SUMMARY OF THE INVENTION

The present disclosure is made to alleviate or solve at least one aspect of the above-mentioned problems in the prior art.

According to an aspect of the embodiments of the present disclosure, a bulk acoustic wave resonator is proposed, comprising:

base;

acoustic mirror;

bottom electrode;

piezoelectric layer; and

top electrode,

in:

The overlapping area of the top electrode, the piezoelectric layer and the bottom electrode in the thickness direction of the resonator constitutes an effective area of the resonator;

The piezoelectric layer includes a first layer and a second layer, an acoustic resistance layer is arranged between the first layer and the second layer, the second layer is above the first layer, and the inner edge of the acoustic resistance layer is in the horizontal direction On the inner side of the boundary of the acoustic mirror, the acoustic resistance of the acoustic resistance layer is different from the acoustic resistance of the piezoelectric layer;

The resonator also includes a channel or opening that communicates the acoustically resistive layer to the outside.

Embodiments of the present disclosure also relate to a bulk acoustic wave resonator assembly, comprising at least two bulk acoustic wave resonators, wherein at least one bulk acoustic wave resonator is the above-mentioned resonator.

Embodiments of the present disclosure also relate to a method of manufacturing a bulk acoustic wave resonator,

The resonator includes a substrate, an acoustic mirror, a bottom electrode, a piezoelectric layer and a top electrode, the piezoelectric layer includes a first layer and a second layer, and a non-electrode connection end of the top electrode is arranged between the first layer and the second layer A voided layer, the method comprising the steps of:

forming and patterning a sacrificial layer on the first layer; and

Cover the first layer and the sacrificial layer thereon with the second layer,

in:

The method further includes the steps of: at the non-electrode connection end of the top electrode, removing the second layer by etching to expose the outer end of the sacrificial layer; and releasing the sacrificial layer to form the void layer; or

The method further includes the steps of: forming a release channel in the second layer penetrating the second layer in the thickness direction of the second layer outside the non-electrode connection end of the top electrode; and releasing the sacrificial layer via the release channel to form the void layer.

Embodiments of the present disclosure also relate to a filter comprising the resonator or assembly described above.

Embodiments of the present disclosure also relate to an electronic device comprising the above-mentioned filter or the above-mentioned resonator or the above-mentioned assembly.

Description of drawings

These and other features and advantages of the various embodiments disclosed in this disclosure may be better understood by the following description and accompanying drawings, wherein like reference numerals refer to like parts throughout, wherein:

1 is a schematic top view of a bulk acoustic wave resonator according to an exemplary embodiment of the present disclosure;

2-4 are schematic cross-sectional views of a bulk acoustic wave resonator along the MOM' line in FIG. 1 according to various exemplary embodiments of the present disclosure;

FIG. 5 exemplarily shows the relationship between the width of the AW structure and the electromechanical coupling coefficient;

FIG. 6 exemplarily shows the width of the AW structure and the parallel resonance impedance of the bulk acoustic wave resonator in the case where the AW structure is provided in the piezoelectric layer and in the case where the AW structure is provided between the top electrode and the piezoelectric layer, respectively The relationship diagram between;

FIG. 7 exemplarily shows the case where the AW structure is provided in the piezoelectric layer and the upper piezoelectric layer is removed and the case where the AW is provided in the piezoelectric layer and the upper piezoelectric layer is not removed, respectively, The relationship between the width of the AW structure and the parallel resonance impedance of the bulk acoustic wave resonator;

8-10 are schematic cross-sectional views of a bulk acoustic wave resonator along the MOM' line in FIG. 1 according to various exemplary embodiments of the present disclosure;

11 is a schematic top view of a bulk acoustic wave resonator according to another exemplary embodiment of the present disclosure;

12 is a schematic cross-sectional view of a bulk acoustic wave resonator along the MOM' line in FIG. 11 according to an exemplary embodiment of the present disclosure;

13 is a schematic top view of a bulk acoustic wave resonator according to yet another exemplary embodiment of the present disclosure;

14 is a schematic top view of a bulk acoustic wave resonator according to still another exemplary embodiment of the present disclosure;

15 is a schematic cross-sectional view of a bulk acoustic wave resonator along the MOM' line in FIG. 14 according to an exemplary embodiment of the present disclosure;

16A-16G exemplarily show cross-sectional schematic diagrams of the manufacturing process of the bulk acoustic wave resonator in FIG. 15;

17 is a schematic cross-sectional view exemplarily showing that the acoustic resistance layer is provided in the middle of the piezoelectric layer and the piezoelectric layer on the upper side is not removed.

detailed description

The technical solutions of the present disclosure will be further specifically described below through the embodiments and in conjunction with the accompanying drawings. The following description of the embodiments of the present disclosure with reference to the accompanying drawings is intended to explain the general disclosed concept of the present disclosure, and should not be construed as a limitation of the present disclosure.

First of all, the reference numerals in the drawings of the present disclosure are explained as follows:

10: Substrate, optional materials are single crystal silicon, gallium nitride, gallium arsenide, sapphire, quartz, silicon carbide, diamond, etc.

20: Acoustic mirror, which can be a cavity, or a Bragg reflector and other equivalent forms. The embodiment of the present disclosure adopts the form of a cavity.

20A: a release channel, which communicates the release hole 90 with the cavity of the acoustic mirror.

21: Sacrificial layer, when the acoustic mirror is in the form of a cavity, it is set in the cavity during the process of preparing the resonator, and is released in the subsequent process to form the cavity of the acoustic mirror. The sacrificial layer 21 can be optionally two. Silicon oxide, doped silicon dioxide, polysilicon, amorphous silicon and other materials.

30: Bottom electrode (including bottom electrode pins), the material can be selected from molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or a composite of the above metals or their alloys.

41: The first piezoelectric layer, which can be a single crystal piezoelectric material, optional, such as: single crystal aluminum nitride, single crystal gallium nitride, single crystal lithium niobate, single crystal lead zirconate titanate (PZT), Materials such as single crystal potassium niobate, single crystal quartz film, or single crystal lithium tantalate can also be polycrystalline piezoelectric materials (corresponding to single crystals, non-single crystal materials), optional, such as polycrystalline nitridation Aluminum, zinc oxide, PZT, etc., can also be a rare earth element doped material containing a certain atomic ratio of the above materials, for example, can be doped aluminum nitride, and doped aluminum nitride contains at least one rare earth element, such as scandium (Sc) , Yttrium (Y), Magnesium (Mg), Titanium (Ti), Lanthanum (La), Cerium (Ce), Praseodymium (Pr), Neodymium (Nd), Promethium (Pm), Samarium (Sm), Europium (Eu) , gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), etc.

42: The second piezoelectric layer, the material of which can be a single crystal piezoelectric material, optional, such as: single crystal aluminum nitride, single crystal gallium nitride, single crystal lithium niobate, single crystal lead zirconate titanate (PZT ), single crystal potassium niobate, single crystal quartz film, or single crystal lithium tantalate, etc., or polycrystalline piezoelectric material (corresponding to single crystal, non-single crystal material), optional, such as polycrystalline Aluminum nitride, zinc oxide, PZT, etc., can also be a rare earth element doped material containing a certain atomic ratio of the above materials, for example, can be doped aluminum nitride, and doped aluminum nitride contains at least one rare earth element, such as scandium ( Sc), Yttrium (Y), Magnesium (Mg), Titanium (Ti), Lanthanum (La), Cerium (Ce), Praseodymium (Pr), Neodymium (Nd), Promethium (Pm), Samarium (Sm), Europium ( Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu) and the like.

50: Top electrode (including top electrode pins), the material can be selected from molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or a composite of the above metals or their alloys.

70: Passivation layer or process layer, which can be aluminum nitride, silicon nitride or silicon dioxide, etc.

80: Acoustic resistance layer, the acoustic resistance of which is different from the acoustic resistance of the first piezoelectric layer 41 and the second piezoelectric layer 42, in the embodiment illustrated in the present disclosure, in the form of an air gap (ie AW), but also It may be in the form of a solid dielectric layer, such as silicon dioxide or its dopants, or silicon nitride or its dopants. As can be appreciated, the acoustic resistance of the acoustic resistance layer may also be greater than the acoustic resistance of the first piezoelectric layer and the second piezoelectric layer.

81: A sacrificial layer, which is set at the position corresponding to the air gap during the process of preparing the resonator, and is released in the subsequent process to form the air gap. The sacrificial layer 81 can be selected from silicon dioxide, doped silicon dioxide, and polysilicon , amorphous silicon and other materials.

90: a release hole for releasing the sacrificial layer material in the cavity of the acoustic mirror.

91: a release channel for releasing the sacrificial layer material in the void layer.

1 is a schematic top view of a bulk acoustic wave resonator according to an exemplary embodiment of the present disclosure, and FIG. 2 is a schematic cross-sectional view of the bulk acoustic wave resonator along the MOM' line in FIG. 1 according to an exemplary embodiment of the present disclosure .

1-2, the BAW resonator includes a substrate 10, an acoustic mirror cavity 20 disposed in the substrate 10, a bottom electrode 30, a top electrode 50, and a piezoelectric layer including a first piezoelectric layer 41 and a piezoelectric layer. The second piezoelectric layer 42 . An acoustic resistance layer 80 in the form of an air gap is provided between the first piezoelectric layer and the second piezoelectric layer. Passivation layer 70 is also shown in FIGS. 1-2.

FIG. 7 exemplarily shows the case in which the AW structure is provided in the piezoelectric layer and the upper piezoelectric layer is removed (in FIG. 7 , corresponding to the solid line, for example, see FIGS. 2-4 , 8 -10) and in the case where the AW is arranged in the piezoelectric layer and the upper piezoelectric layer is not removed (in Fig. 7, corresponding to the dotted line, for example, see Fig. 17 for an embodiment), the width of the AW structure is related to the bulk acoustic wave Graph of the relationship between the parallel resonant impedances of the resonators.

As can be seen from FIG. 7, in most cases, the AW structure is placed between two piezoelectric layers and the second piezoelectric layer 42 is etched or removed along the boundary of the non-electrode connection end of the top electrode. The performance is significantly better than the device performance when the second piezoelectric layer is not etched or removed under the same conditions.

In FIG. 2, the portion of the first piezoelectric layer 41 outside the AW structure 80 is not etched, that is, at the non-electrode connection end of the top electrode, the portion of the first layer outside the outer edge of the acoustic resistance layer is not etched. The thickness is equal to the thickness of the portion located inside the outer edge of the acoustically resistive layer. Corresponding to the structure shown in FIG. 2, when the top electrode is etched, the second piezoelectric layer 42 is etched together, so that the second piezoelectric layer 42, the top electrode and the passivation layer form the same etching surface. . The first piezoelectric layer 41 under the AW structure 80 is not etched in the inactive area of the resonator, but the second piezoelectric layer 42 is etched, so at the non-electrode connection end of the top electrode of the resonator, resonance There is no second piezoelectric layer in the inactive region of the device. In this case, the AW structure 80 at the non-electrode connection end, the second piezoelectric layer 41 , the non-electrode connection end of the top electrode, and the passivation layer 70 form the same etching surface. It should be noted that it is not required that the end surfaces of the passivation layer 70 and the non-electrode connection end of the top electrode are flush.

3 is a schematic cross-sectional view of a bulk acoustic wave resonator similar to the MOM' line in FIG. 1 according to an exemplary embodiment of the present disclosure. The difference between FIG. 3 and FIG. 2 is that, in FIG. 3 , the first piezoelectric The portion of the layer 41 on the outside of the AW structure 80 is partially etched, while in FIG. 2 the corresponding portion of the first piezoelectric layer 41 is not etched. That is, in FIG. 3 , at the non-electrode connection end of the top electrode, the thickness of the portion of the first layer outside the outer edge of the acoustic resistance layer is smaller than the thickness of the portion inside the outer edge of the acoustic resistance layer. In the actual preparation process, when etching the second piezoelectric layer 42, a certain amount of overetching is required, and because the etching selection of the materials of the first piezoelectric layer 41 and the second piezoelectric layer 42 is relatively small or because the same Although the materials have the same etching rate, the first piezoelectric layer 41 may be etched to a certain extent in the process of etching the second piezoelectric layer 42 , thereby obtaining the structure shown in FIG. 3 . In this case, the first piezoelectric layer 41 is partially etched.

4 is a schematic cross-sectional view of a bulk acoustic wave resonator similar to the MOM' line in FIG. 1 according to an exemplary embodiment of the present disclosure. The difference between FIG. 4 and FIG. 2 is that, in FIG. 4 , the first piezoelectric The portions of the layer 41 outside the AW structure 80 are all etched away, while in FIG. 2 , the corresponding portions of the first piezoelectric layer are not etched. That is, in FIG. 4, at the non-electrode connection end of the top electrode, the portion of the first layer that is outside the outer edge of the acoustic resistance layer is removed. That is, in the process of etching the second piezoelectric layer 42 , the first piezoelectric layer 41 may be etched away together, thereby obtaining the structure of FIG. 4 .

In FIGS. 2-4 , after being etched or removed, the end face of the second piezoelectric layer 42 is a vertical end face and is flush with the end face of the non-electrode connection end of the top electrode, but the present disclosure is not limited thereto.

8-10 are schematic cross-sectional views of a bulk acoustic wave resonator along the MOM' line in FIG. 1 according to various exemplary embodiments of the present disclosure. In FIG. 8 , although the end face of the second piezoelectric layer 42 is still a vertical end face, the end face of the non-electrode connection end of the top electrode is located outside the end face of the second piezoelectric layer 42 in the horizontal direction, and the two end faces are in the horizontal direction. There is a distance Δd in the horizontal direction. In FIG. 9 , although the end face of the second piezoelectric layer 42 is still a vertical end face, the end face of the non-electrode connection end of the top electrode is located inside the end face of the second piezoelectric layer 42 in the horizontal direction, and the two end faces are in the horizontal direction. There is a distance Δd in the horizontal direction. In FIG. 10 , the end face of the second piezoelectric layer 42 is inclined outward, and the end face of the non-electrode connection end of the top electrode is located inside the end face of the second piezoelectric layer 42 in the horizontal direction, and the two end faces are horizontal There is a distance Δd in the direction, and in FIG. 10 , the inclination angle of the slope of the second piezoelectric layer 42 is α. In embodiments of the present disclosure, Δd is between 0.25-5 μm. As can be understood by those skilled in the art, the above-mentioned outwardly inclined inclined surface may also be an inwardly inclined inclined surface. In the embodiment of the present disclosure, the inclination angle α of the inclined plane is in the range of 10-80 degrees.

In the embodiments of FIGS. 2-4 and 8-10, a portion of the second piezoelectric layer 42 is removed (eg, cut by etching) at the non-electrode connection end of the top electrode, thereby directly exposing the AW structure or the acoustic resistance layer or air gap. In this way, the air reflective surface formed after cutting can prevent energy or lateral Lamb waves from leaking through the second piezoelectric layer outside the AW structure, as shown in FIG. 7 , thereby improving the performance of the resonator. More specifically, since an air reflection surface (impedance mismatch interface) is formed at the non-electrode connection end corresponding to the second piezoelectric layer 42, the transverse Lamb wave forms a strong reflection at the air reflection surface, thereby reducing the lateral The Lamb wave leakage increases the Q of the resonator. If only the AW structure is provided and the second piezoelectric layer 42 is not etched, the second piezoelectric layer 42 is a continuous interface, and the lateral Lamb waves can leak out of the effective area through the second piezoelectric layer 42, thereby reducing the the Q value of the resonator.

In addition, when the etched interface of the second piezoelectric layer 42 and the end face of the non-electrode connection end of the top electrode are not at the same interface, more lateral Lamb waves can be reflected than when the two are at the same interface. Taking FIG. 8 as an example, the second piezoelectric layer 42 can effectively reflect the transverse wave whose 1/4 of the transverse wavelength is L1, and the top electrode can effectively reflect the transverse wave whose 1/4 of the transverse wavelength is L1+Δd. . However, when the etched interface of the second piezoelectric layer 42 is flush with the end face of the non-electrode connecting end of the top electrode, the structure can only effectively reflect the transverse wave with a wavelength L1 of 1/4 of the transverse wavelength. In addition, as shown in FIG. 10 , when the end face of the second piezoelectric layer 42 is inclined, there are two distances between the second piezoelectric layer, L2 is the distance from the inner edge of the AW structure to the outer edge of the upper surface, and L3 is the inner edge of the AW structure Distance to the outer edge of the lower surface. Therefore, the second piezoelectric layer 42 can effectively reflect the transverse wave whose wavelength is between L2 and L3, which is 1/4 of the transverse wavelength. Therefore, more waves can be reflected, so the Q value will be higher.

In the embodiments shown in FIGS. 2-4 and 8-10, the second piezoelectric layer 42 is removed at the non-electrode connection end of the top electrode to expose the AW structure or the acoustic resistance layer or the air gap, but this disclosure does not limited to this.

11 is a schematic top view of a bulk acoustic wave resonator according to another exemplary embodiment of the present disclosure, and FIG. 12 is a cross-section of the bulk acoustic wave resonator along the MOM' line in FIG. 11 according to an exemplary embodiment of the present disclosure Schematic. In FIGS. 11-12 , the second piezoelectric layer 42 is provided with a channel 91 on the outside of the non-electrode connection end of the top electrode to communicate with the AW structure or void layer 80 .

As shown in FIG. 11 , the void layer 80 is continuously arranged along the circumferential direction of the effective area at least at the non-electrode connection end of the top electrode, and correspondingly, the channel 91 is a continuous channel arranged along the circumferential direction of the effective area.

By arranging the channel 91, it can be used to release the sacrificial layer material in the void layer 80 to form the void layer. At this time, the channel 91 is the release channel. Cut-off or partial cut-off processing, which can also prevent or reduce energy leakage during the operation of the resonator. The effect of preventing or reducing energy leakage can be seen, for example, in FIG. 7 .

The channel 91 may also only serve to prevent or reduce energy leakage during the operation of the resonator. At this time, the acoustic resistance layer 80 is not in the form of a void layer, but in the form of a solid medium layer.

In the diagrams shown in FIGS. 2-4 and 8-12, the acoustic resistive layers 80 are in the form of a continuous arrangement, but the present disclosure is not limited thereto. 13 is a schematic top view of a bulk acoustic wave resonator according to still another exemplary embodiment of the present disclosure, and a cross-sectional view taken along the MOM' line in FIG. 13 is similar to FIG. 12 . In Figure 13, it can be seen that the acoustically resistive layer 80 includes a plurality of acoustically resistive portions that are spaced apart in the circumferential direction along the effective area of the resonator. Correspondingly, the channel 91 may include a plurality of holes communicating with the plurality of acoustic resistance parts respectively (corresponding to the case of partial cutting process), or may be arranged along the circumferential direction of the effective area and communicate with each acoustic resistance part. A continuous channel that is connected to each other (corresponding to a cut-off situation at this time).

FIG. 6 exemplarily shows the width of the AW structure and the parallel resonance impedance of the bulk acoustic wave resonator in the case where the AW structure is provided in the piezoelectric layer and in the case where the AW structure is provided between the top electrode and the piezoelectric layer, respectively diagram of the relationship between them. In FIG. 6 , the abscissa is the width of the AW structure (unit is μm), and the ordinate is the parallel resonance impedance Rp of the resonator (unit is ohm). In FIG. 6 , the broken line represents the case where the AW structure is provided between the top electrode and the piezoelectric layer, and the solid line represents the case where the AW structure is provided in the piezoelectric layer. As shown in Fig. 6, the value of the parallel resonance impedance when the AW structure is in the piezoelectric layer is significantly higher than the value of the parallel resonance impedance when the AW structure is between the piezoelectric layer and the top electrode. It can be seen that by disposing the acoustic resistance layer 80 between the first piezoelectric layer 41 and the second piezoelectric layer 42 , the performance of the resonator can be effectively improved compared to disposing the acoustic resistance layer between the top electrode and the piezoelectric layer.

By providing the acoustic resistance layer 80 between the first piezoelectric layer 41 and the second piezoelectric layer 42, the value of the electromechanical coupling coefficient of the resonator can also be adjusted. Since the first piezoelectric layer 41 and the second piezoelectric layer 42 are prepared separately, the two piezoelectric layers can be prepared as different materials, so that the electromechanical coupling coefficient of the resonator can be freely adjusted. For example, the first piezoelectric layer 41 is a piezoelectric layer of a certain material (for example, a piezoelectric layer of a material selected from aluminum nitride, zinc oxide, lead zirconate titanate, lithium niobate, quartz, potassium niobate, and lithium tantalate). electric layer), and the second piezoelectric layer 42 is a doped layer doped with at least one rare earth element as mentioned above in the same material layer as the material of the first piezoelectric layer 41, in a specific embodiment , the first piezoelectric layer 41 and the second piezoelectric layer 42 are both piezoelectric materials based on aluminum nitride, but one layer of the piezoelectric material is a piezoelectric material without any doping, and the other layer is a doping element scandium piezoelectric material. For another example, the first piezoelectric layer and the second piezoelectric layer are both doped layers of the same material, but the doping concentration of the first piezoelectric layer is different from the doping concentration of the second piezoelectric layer. In the example, the first piezoelectric layer 41 and the second piezoelectric layer 42 are both piezoelectric materials based on aluminum nitride doped with rare earth element scandium, but the doping concentration of the first piezoelectric layer and the second piezoelectric layer is different. . For another example, the material of the first piezoelectric layer 41 is one of aluminum nitride, zinc oxide, lead zirconate titanate, lithium niobate, quartz, potassium niobate, and lithium tantalate, and the second piezoelectric layer 42 It is a material different from the material of the first piezoelectric layer among aluminum nitride, zinc oxide, lead zirconate titanate, lithium niobate, quartz, potassium niobate, and lithium tantalate. In a specific embodiment, the first piezoelectric The layer is aluminum nitride and the second piezoelectric layer is zinc oxide.

Therefore, in the present disclosure, while improving the performance of the resonator by arranging the AW structure in the piezoelectric layer, it is also possible to prepare different piezoelectric layers on the upper and lower sides of the AW structure to realize the free setting of the electromechanical coupling coefficient of the resonator .

The above arrangement of the

piezoelectric layers

41 and 42 with different doping can adjust the electromechanical coupling coefficient of the resonator to a relatively large extent. For example, to make a duplexer in the same Die, the electromechanical coupling coefficient of the resonator in the transmit filter Tx and the electromechanical coupling coefficient of the resonator in the receive filter Rx need to be quite different (greater than 1%), but in Inside the transmitting filter Tx or the receiving filter Rx, the electromechanical coupling coefficient between different resonators needs to have a small difference (less than 1%). At this time, the width of the AW structure in the effective area of the resonator can be adjusted, and The electromechanical coupling coefficient of the resonator inside the filter is adjusted by adjusting the width L1 of the AW structure in FIG. 2 . As shown in FIG. 2 , L1 is the width of the AW structure at the non-electrode connection end of the top electrode, which is the horizontal distance between the non-electrode connection end of the top electrode and the inner edge of the AW structure.

The acoustic resistance layer can also be further disposed on the electrode connection end of the top electrode, and FIGS. 14-15 show such an embodiment. 14 is a schematic top view of a bulk acoustic wave resonator according to still another exemplary embodiment of the present disclosure, and FIG. 15 is a cross-section of the bulk acoustic wave resonator along the MOM' line in FIG. 14 according to an exemplary embodiment of the present disclosure Schematic. At this time, the width of the AW structure in the effective area of the resonator can be adjusted, that is, the electromechanical coupling coefficient of the resonator inside the filter can be adjusted by adjusting the widths L1 and L2 of the AW structure in FIG. 15 . As shown in Figure 15, L1 is the width of the AW structure at the non-electrode connection end of the top electrode, which is the distance between the non-electrode connection end of the top electrode and the inner edge of the AW structure in the horizontal direction; as shown in Figure 15, L2 is the width of the AW structure at the electrode connection end of the top electrode, which is the distance in the horizontal direction between the boundary of the acoustic mirror and the inner edge of the AW structure at the connection end of the top electrode.

FIG. 5 exemplarily shows the relationship between the width of the AW structure or the air gap and the electromechanical coupling coefficient. In FIG. 5 , the abscissa is the width of the AW structure (unit is μm), and the ordinate is the electromechanical coupling coefficient. Figure 5 shows the influence of the width of the AW structure of the resonator on the electromechanical coupling coefficient when the width of the AW structure on each side of the effective area of the resonator is the same. As shown in Figure 5, the electromechanical coupling coefficient increases with the increase of the AW width. slowing shrieking. It can be seen that the electromechanical coupling coefficient of the resonator can be adjusted by adjusting the width of the AW structure.

For a resonator whose active area is a polygon, the width of the AW structure on each side can be the same or different.

The AW structure or the acoustic resistance layer or the air gap can only be arranged at the non-electrode connection end of the top electrode, as shown in Figures 2-4 and 8-13; it can also be arranged at the non-electrode connection end and the electrode connection end of the top electrode at the same time, As shown in Figure 14-15.

In the present disclosure, for example, as shown in FIGS. 2-4 and 8-13, an AW structure or an acoustic resistance layer or an air gap is provided at the non-electrode connection end of the top electrode. In the case where the effective area of the resonator is a polygon, it can be It includes the case where it is provided only on one side or a plurality of sides of the non-electrode connection end, and may also include the case where it is provided on all sides of the non-electrode connection end.

In the present disclosure, see, for example, FIGS. 14-15 , an AW structure or an acoustic resistive layer or an air gap is provided at the electrode connection end of the top electrode, and in the case where the effective area of the resonator is a polygon, it is indicated at the electrode connection end of the top electrode The side where it is located is provided with an AW structure or an acoustic resistance layer or an air gap.

An AW structure or an acoustically resistive layer or an air gap can also be provided around the entire active area of the resonator.

When the thickness of the piezoelectric layer is constant, when the same piezoelectric material is used on the upper and lower sides of the AW structure, no matter where the AW structure is located in the piezoelectric layer, under the same conditions, the electromechanical properties of the resonator will The coupling coefficient is a definite value. However, when different piezoelectric layer materials are used on the upper and lower sides of the AW structure, the design freedom of the electromechanical coupling coefficient of the resonator can be increased. For example, the first piezoelectric layer 41 is made of undoped aluminum nitride material, and the second piezoelectric layer 42 is made of scandium-doped aluminum nitride material. When the thickness of the piezoelectric layer is fixed, the electromechanical coupling coefficient is 6% when the piezoelectric layer only uses undoped aluminum nitride piezoelectric layer, and the electromechanical coupling coefficient is 10% when the piezoelectric layer only uses doped aluminum nitride. . Therefore, when the thickness of the piezoelectric layer is constant, by controlling the doping concentration of the first piezoelectric layer 41 and the second piezoelectric layer 42, the electromechanical coupling coefficient of the resonator can be freely changed between 6% and 10%. After the thicknesses of the two piezoelectric layers are determined respectively, then the electromechanical coupling coefficients of different resonators in the filter can be fine-tuned by controlling the change of the width of the AW structure, so this scheme can maximize the increase in the efficiency of the filter. Design freedom for the electromechanical coupling coefficient of the resonator.

In FIG. 2, the materials of the first piezoelectric layer 41 and the second piezoelectric layer 42 may be different. When the thicknesses of the first piezoelectric layer 41 and the second piezoelectric layer 42 are fixed, a certain electromechanical coupling of the resonator The required electromechanical coupling coefficient can be achieved by changing the material of the piezoelectric layer. After the doping or materials of the first piezoelectric layer 41 and the second piezoelectric layer 42 are determined, the electromechanical coupling coefficient of the resonator can be further adjusted by changing the width L1 in FIG. 2 .

In FIG. 15, the materials of the first piezoelectric layer 41 and the second piezoelectric layer 42 may be different, and when the thicknesses of the first piezoelectric layer 41 and the second piezoelectric layer 42 are fixed, a certain electromechanical coupling of the resonator The required electromechanical coupling coefficient can be achieved by changing the material of the piezoelectric layer. After the doping or materials of the first piezoelectric layer 41 and the second piezoelectric layer 42 are determined, the electromechanical coupling coefficient of the resonator can be further adjusted by changing the widths L1 and L2 in FIG. 15 .

Also shown in FIG. 2 are the thicknesses of the first piezoelectric layer 41 and the second piezoelectric layer 42, which are H1 and H2, respectively. The ratio of two different piezoelectric materials can be adjusted by adjusting the ratio of H1 and H2, thereby adjusting the electromechanical coupling coefficient of the resonator. When H2 and H1 are determined, similarly, the electromechanical coupling coefficient of the resonator can be further adjusted by changing the widths of the widths L1 and L2 in FIG. 2 .

As shown in FIG. 2 , the position of the AW structure sandwiched between the first piezoelectric layer 41 and the second piezoelectric layer 42 is not fixed. In one embodiment of the present disclosure, the distance between the lower surface of the AW structure and the lower surface of the first piezoelectric layer 41 is greater than

The distance between the upper surface of the AW structure and the second piezoelectric layer 42 is also greater than

The range of thickness of the AW structure is

The fabrication process of the bulk acoustic wave resonator in FIGS. 14-15 is exemplarily described below with reference to FIGS. 16A-16G . It should be pointed out that this manufacturing process can also be used in the case where the acoustic resistance layer is only provided on the non-electrode connection end of the top electrode. At this time, different from the following steps, the sacrifice corresponding to the acoustic resistance layer is no longer provided. layer and release of the sacrificial layer.

First, as shown in FIG. 16A , a cavity as the acoustic mirror 20 is formed on the upper surface of the substrate 10, and then a sacrificial material is provided on the upper surface of the substrate 10, the sacrificial material fills the cavity, and then, by CMP (Chemical Mechanical Polishing) ) process removes the sacrificial material on the upper surface of the substrate 10 and makes the upper surface of the sacrificial material in the cavity flush with the upper surface of the substrate 10 to form the sacrificial layer 21 .

Second, as shown in FIG. 16B , a layer of electrode material is deposited and patterned on the structure of FIG. 16A to form bottom electrode 30 .

Third, as shown in FIG. 16C , a first piezoelectric layer 41 is deposited on the structure of FIG. 16B , which may be, for example, an undoped piezoelectric layer.

Fourth, as shown in FIG. 16D , a sacrificial material is deposited and patterned on the upper surface of the first piezoelectric layer 41 of FIG. 16C to form a sacrificial layer 81 . The sacrificial layer 81 will be released for forming the AW structure 80 at a later stage. As shown in FIG. 16D, a sacrificial layer 81 for electrode connection terminals and non-connection terminals of the top electrode is provided.

Fifth, as shown in FIG. 16E , a second piezoelectric layer 42 is deposited on the upper surface of the structure of FIG. 16D , which may be, for example, a doped piezoelectric layer.

Sixth, as shown in FIG. 16F, a top electrode 50 and a protective layer or passivation layer 70 are prepared on the upper surface of the structure of FIG. 16E.

Seventh, at the non-electrode connection end of the top electrode, the passivation layer 70, the top electrode 50 and the second piezoelectric layer 42 are etched to expose the sacrificial layer 81 at the non-electrode connection end of the top electrode.

Eighth, the sacrificial layer 21 and the sacrificial layer 81 are released to form the acoustic mirror 20 and the AW structure 80, respectively, as shown in FIG. 16G.

It should be pointed out that the above method steps are only exemplary, and those skilled in the art can also adjust and change the above steps. For example, the second piezoelectric layer can be prepared and etched first, followed by the preparation of the top electrode and passivation layer.

It should be pointed out that, in the present disclosure, each numerical range, except that it is explicitly stated that it does not include the endpoint value, may be the endpoint value, but also the middle value of each numerical range, and these are all within the protection scope of the present disclosure. .

In the present disclosure, upper and lower are relative to the bottom surface of the substrate, and for a component, the side close to the bottom surface is the lower side, and the side away from the bottom surface is the upper side.

In the present disclosure, inner and outer are in the lateral direction or radial direction relative to the center of the effective area of the resonator (the overlapping area of the piezoelectric layer, the top electrode, the bottom electrode and the acoustic mirror in the thickness direction of the resonator constitutes the effective area). Directionally, the side or end of a component close to the center of the active area is the inner or inner end, and the side or end of the component away from the center of the active area is the outer or outer end. For a reference position, being located inside the position means between the position and the center of the effective area in the lateral or radial direction, and being located outside of the position means more laterally or radially than the position away from the center of the active area.

As can be appreciated by those skilled in the art, bulk acoustic wave resonators may be used to form filters or other semiconductor devices.

Based on the above, the present disclosure proposes the following technical solutions:

1. A bulk acoustic wave resonator, comprising:

base;

acoustic mirror;

bottom electrode;

piezoelectric layer; and

top electrode,

in:

2. The resonator according to 1, wherein:

At the non-electrode connection end of the top electrode, the outer edge of the acoustic resistance layer is flush with the end of the second layer, and the outer edge of the acoustic resistance layer forms or is in the opening; or

Based on the acoustic resistance layer, the non-electrode connection end of the top electrode forms a cantilever structure.

3. The resonator according to 2, wherein:

At the non-electrode connection end of the top electrode, the end face of the end portion of the second layer is a vertical plane or an inclined plane.

4. The resonator according to 2, wherein:

At the non-electrode connection end of the top electrode, the thickness of the portion of the first layer on the outside of the outer edge of the acoustically resistive layer is equal to the thickness of the portion on the inside of the outer edge of the acoustically resistive layer; or

At the non-electrode connection end of the top electrode, the thickness of the portion of the first layer on the outside of the outer edge of the acoustically resistive layer is less than the thickness of the portion on the inside of the outer edge of the acoustically resistive layer; or

At the non-electrode connection end of the top electrode, the portion of the first layer outside the outer edge of the acoustically resistive layer is removed.

5. The resonator according to 2, wherein:

The non-electrode connection end of the top electrode is staggered from the end of the second layer in the horizontal direction.

6. The resonator according to 1, wherein:

The acoustic resistance layer includes a plurality of acoustic resistance portions, the plurality of acoustic resistance portions are spaced apart in the circumferential direction along the effective area of the resonator, and outer edges of the plurality of acoustic resistance portions constitute a circumference along the effective area. a plurality of said openings spaced in the direction; or

The acoustic resistance layer is continuously arranged in the circumferential direction along the effective area of the resonator, and the outer edge of the acoustic resistance layer constitutes the openings continuously arranged in the circumferential direction of the effective area.

7. The resonator according to any one of 2-6, wherein:

The acoustic resistance layer is a void layer or a solid medium layer.

8. The resonator according to 1, wherein:

At the non-electrode connection end of the top electrode, the channel passes through the second layer in the thickness direction of the second layer, the channel is outside the non-electrode connection end of the top electrode in the horizontal direction, and the channel is connected to the second layer. The acoustic resistance layers are communicated or connected to each other.

9. The resonator of 8, wherein:

The acoustic resistance layer is continuously arranged along the circumferential direction of the effective area at least at the non-electrode connection end of the top electrode, and the channel is a continuous channel arranged along the circumference of the effective area and communicated with or connected to the acoustic resistance layer , or the channel includes a plurality of holes spaced circumferentially along the effective area; or

The acoustic resistance layer includes a plurality of acoustic resistance parts, the plurality of acoustic resistance parts are arranged spaced apart in the circumferential direction along the effective area of the resonator, and the channel comprises a plurality of acoustic resistance parts respectively communicating with or in phase with the plurality of acoustic resistance parts; A plurality of holes connected to each other, or the channel is a continuous channel arranged along the circumference of the effective area and communicated with or connected to the plurality of acoustic resistance parts.

10. The resonator according to 8 or 9, wherein:

The acoustic resistance layer is a void layer, and the channel is a release channel communicated with the void layer.

11. The resonator of any of 1-10, wherein:

The piezoelectric material of the first layer is different from the piezoelectric material of the second layer.

12. The resonator of 11, wherein:

One of the first layer and the second layer is a doped layer of the other; or

The first layer and the second layer are both doped layers of the same material, and the doping concentration of the first layer is different from the doping concentration of the second layer; or

The material of the first layer is one of aluminum nitride, zinc oxide, lead zirconate titanate, lithium niobate, quartz, potassium niobate, lithium tantalate, and the second layer is aluminum nitride, zinc oxide, zirconium A material different from the first layer material among lead titanate, lithium niobate, quartz, potassium niobate, and lithium tantalate.

13. The resonator of any of 1-12, wherein:

The acoustic resistance layer includes a non-connecting end acoustic resistance layer at the non-electrode connection end of the top electrode, and the inner edge of the non-connecting end acoustic resistance layer is located inside the non-electrode connection end of the top electrode in the horizontal direction.

14. The resonator of 13, wherein:

The non-electrode connection end of the top electrode is in the inner side of the boundary of the acoustic mirror in the horizontal direction or is flush with the boundary of the acoustic mirror;

In the horizontal direction, there is a first distance between the non-electrode connecting end of the top electrode and the inner edge of the non-connecting end acoustic resistance layer, and the first distance is in the range of 0.25-10 μm.

15. The resonator of 13, wherein:

The acoustic resistance layer further includes a connection end acoustic resistance layer at the electrode connection end of the top electrode.

16. The resonator of 15, wherein:

In the horizontal direction, there is a second distance between the boundary of the acoustic mirror and the inner edge of the acoustic resistance layer at the connection end, and the second distance is in the range of 0.25-10 μm.

17. The resonator of 1, wherein:

The thickness of the first layer is different from the thickness of the second layer.

18. A bulk acoustic wave resonator assembly comprising:

At least two BAW resonators, wherein at least one BAW resonator is the resonator according to any one of 1-17.

19. The assembly of 18, wherein:

the at least two bulk acoustic wave resonators include a first resonator and a second resonator;

Both the first resonator and the second resonator are resonators according to any one of 1-17.

20. The assembly of 19, wherein:

The first resonator and the second resonator are the resonators according to 12.

21. The assembly of 20, wherein:

The difference between the electromechanical coupling coefficient of the first resonator and the electromechanical coupling coefficient of the second resonator is in the range of 0%-10%.

22. The assembly of any of 18-21, wherein:

said first and second resonators are both resonators according to 14 or 16;

The widths of the acoustic resistance layer of the first resonator and the corresponding acoustic resistance layer of the second resonator are different from each other.

23. A method of manufacturing a bulk acoustic wave resonator, the resonator comprising a substrate, an acoustic mirror, a bottom electrode, a piezoelectric layer and a top electrode, the piezoelectric layer comprising a first layer and a second layer, the first layer and the second layer A void layer is arranged between the layers at the non-electrode connection end of the top electrode, and the method includes the steps:

forming and patterning a sacrificial layer on the first layer; and

Cover the first layer and the sacrificial layer thereon with the second layer,

in:

The method further includes the steps of: forming a release channel in the second layer penetrating the second layer in the thickness direction of the second layer outside the non-electrode connection end of the top electrode; and releasing the sacrificial layer via the release channel to form the the void layer.

24. A filter comprising the BAW resonator of any one of 1-17, or the BAW resonator assembly of any one of 18-22.

25. An electronic device comprising the filter according to 24, or the BAW resonator according to any one of 1-17, or the BAW resonator assembly according to any one of 18-22 .

The electronic equipment here includes but is not limited to intermediate products such as RF front-end, filter and amplifier modules, and terminal products such as mobile phones, WIFI, and drones.

Although embodiments of the present disclosure have been shown and described, it will be understood by those skilled in the art that changes may be made to these embodiments without departing from the principles and spirit of the present disclosure, the scope of which is determined by It is defined by the appended claims and their equivalents.

Claims

A bulk acoustic wave resonator, comprising:

base;

acoustic mirror;

bottom electrode;

piezoelectric layer; and

top electrode,

in:

The overlapping area of the top electrode, the piezoelectric layer and the bottom electrode in the thickness direction of the resonator constitutes an effective area of the resonator;

The piezoelectric layer includes a first layer and a second layer, an acoustic resistance layer is arranged between the first layer and the second layer, the second layer is above the first layer, and the inner edge of the acoustic resistance layer is in the horizontal direction On the inner side of the boundary of the acoustic mirror, the acoustic resistance of the acoustic resistance layer is different from the acoustic resistance of the piezoelectric layer;

The resonator also includes a channel or opening that communicates the acoustically resistive layer to the outside.
The resonator of claim 1, wherein:

At the non-electrode connection end of the top electrode, the outer edge of the acoustic resistance layer is flush with the end of the second layer, and the outer edge of the acoustic resistance layer forms or is in the opening; or

Based on the acoustic resistance layer, the non-electrode connection end of the top electrode forms a cantilever structure.
The resonator of claim 2, wherein:

At the non-electrode connection end of the top electrode, the end face of the end portion of the second layer is a vertical plane or an inclined plane.
The resonator of claim 2, wherein:

At the non-electrode connection end of the top electrode, the thickness of the portion of the first layer on the outside of the outer edge of the acoustically resistive layer is equal to the thickness of the portion on the inside of the outer edge of the acoustically resistive layer; or

At the non-electrode connection end of the top electrode, the thickness of the portion of the first layer on the outside of the outer edge of the acoustically resistive layer is less than the thickness of the portion on the inside of the outer edge of the acoustically resistive layer; or

At the non-electrode connection end of the top electrode, the portion of the first layer outside the outer edge of the acoustically resistive layer is removed.
The resonator of claim 2, wherein:

The non-electrode connection end of the top electrode is staggered from the end of the second layer in the horizontal direction.
The resonator of claim 1, wherein:

The acoustic resistance layer includes a plurality of acoustic resistance portions, the plurality of acoustic resistance portions are spaced apart in the circumferential direction along the effective area of the resonator, and outer edges of the plurality of acoustic resistance portions constitute a circumference along the effective area. a plurality of said openings spaced in the direction; or

The acoustic resistance layer is continuously arranged in the circumferential direction along the effective area of the resonator, and the outer edge of the acoustic resistance layer constitutes the openings continuously arranged in the circumferential direction of the effective area.
The resonator of any of claims 2-6, wherein:

The acoustic resistance layer is a void layer or a solid medium layer.
The resonator of claim 1, wherein:

At the non-electrode connection end of the top electrode, the channel passes through the second layer in the thickness direction of the second layer, the channel is outside the non-electrode connection end of the top electrode in the horizontal direction, and the channel is connected to the second layer. The acoustic resistance layers are communicated or connected to each other.
The resonator of claim 8, wherein:

The acoustic resistance layer is continuously arranged along the circumferential direction of the effective area at least at the non-electrode connection end of the top electrode, and the channel is a continuous channel arranged along the circumference of the effective area and communicated with or connected to the acoustic resistance layer , or the channel includes a plurality of holes spaced circumferentially along the effective area; or

The acoustic resistance layer includes a plurality of acoustic resistance parts, the plurality of acoustic resistance parts are arranged spaced apart in the circumferential direction along the effective area of the resonator, and the channel comprises a plurality of acoustic resistance parts respectively communicating with or in phase with the plurality of acoustic resistance parts; A plurality of holes connected to each other, or the channel is a continuous channel arranged along the circumference of the effective area and communicated with or connected to the plurality of acoustic resistance parts.
A resonator according to claim 8 or 9, wherein:

The acoustic resistance layer is a void layer, and the channel is a release channel communicated with the void layer.
The resonator of any of claims 1-10, wherein:

The piezoelectric material of the first layer is different from the piezoelectric material of the second layer.
The resonator of claim 11, wherein:

One of the first layer and the second layer is a doped layer of the other; or

The first layer and the second layer are both doped layers of the same material, and the doping concentration of the first layer is different from the doping concentration of the second layer; or

The material of the first layer is one of aluminum nitride, zinc oxide, lead zirconate titanate, lithium niobate, quartz, potassium niobate, lithium tantalate, and the second layer is aluminum nitride, zinc oxide, zirconium A material different from the first layer material among lead titanate, lithium niobate, quartz, potassium niobate, and lithium tantalate.
The resonator of any of claims 1-12, wherein:

The acoustic resistance layer includes a non-connecting end acoustic resistance layer at the non-electrode connection end of the top electrode, and the inner edge of the non-connecting end acoustic resistance layer is located inside the non-electrode connection end of the top electrode in the horizontal direction.
The resonator of claim 13, wherein:

The non-electrode connection end of the top electrode is in the inner side of the boundary of the acoustic mirror in the horizontal direction or is flush with the boundary of the acoustic mirror;

In the horizontal direction, there is a first distance between the non-electrode connecting end of the top electrode and the inner edge of the non-connecting end acoustic resistance layer, and the first distance is in the range of 0.25-10 μm.
The resonator of claim 13, wherein:

The acoustic resistance layer further includes a connection end acoustic resistance layer at the electrode connection end of the top electrode.
The resonator of claim 15, wherein:

In the horizontal direction, there is a second distance between the boundary of the acoustic mirror and the inner edge of the acoustic resistance layer at the connection end, and the second distance is in the range of 0.25-10 μm.
The resonator of claim 1, wherein:

The thickness of the first layer is different from the thickness of the second layer.
A bulk acoustic wave resonator assembly, comprising:

At least two bulk acoustic wave resonators, wherein at least one bulk acoustic wave resonator is a resonator according to any one of claims 1-17.
The assembly of claim 18, wherein:

the at least two bulk acoustic wave resonators include a first resonator and a second resonator;

Both the first resonator and the second resonator are resonators according to any one of claims 1-17.
The assembly of claim 19, wherein:

The first resonator and the second resonator are resonators according to claim 12 .
The assembly of claim 20, wherein:

The difference between the electromechanical coupling coefficient of the first resonator and the electromechanical coupling coefficient of the second resonator is in the range of 0%-10%.
The assembly of any of claims 18-21, wherein:

Both the first resonator and the second resonator are resonators according to claim 14 or 16;

The widths of the acoustic resistance layer of the first resonator and the corresponding acoustic resistance layer of the second resonator are different from each other.
A method for manufacturing a bulk acoustic wave resonator, the resonator includes a substrate, an acoustic mirror, a bottom electrode, a piezoelectric layer and a top electrode, the piezoelectric layer includes a first layer and a second layer, and the first layer and the second layer are between the first layer and the second layer. A void layer is arranged between the non-electrode connection ends of the top electrode, and the method includes the steps:

forming and patterning a sacrificial layer on the first layer; and

Covering the first layer and the sacrificial layer thereon with the second layer,

in:

The method further includes the steps of: at the non-electrode connection end of the top electrode, removing the second layer by etching to expose the outer end of the sacrificial layer; and releasing the sacrificial layer to form the void layer; or

The method further includes the steps of: forming a release channel in the second layer penetrating the second layer in the thickness direction of the second layer outside the non-electrode connection end of the top electrode; and releasing the sacrificial layer via the release channel to form the the void layer.
A filter comprising a bulk acoustic wave resonator according to any one of claims 1-17, or a bulk acoustic wave resonator assembly according to any one of claims 18-22.
An electronic device comprising a filter according to claim 24, or a bulk acoustic wave resonator according to any one of claims 1-17, or a bulk acoustic wave resonator according to any one of claims 18-22 Acoustic resonator assembly.