CN114257208A

Movatterモバイル変換

Info

Publication number: CN114257208A
Application number: CN202011002147.6A
Authority: CN
Inventors: 庞慰; 班圣光; 杨清瑞; 张孟伦
Original assignee: ROFS Microsystem Tianjin Co Ltd
Current assignee: ROFS Microsystem Tianjin Co Ltd
Priority date: 2020-09-22
Filing date: 2020-09-22
Publication date: 2022-03-29
Also published as: WO2022062910A1

Abstract

The invention relates to a bulk acoustic wave resonator comprising: a substrate; an acoustic mirror; a bottom electrode; a piezoelectric layer; and a top electrode, wherein: the piezoelectric layer comprises a first layer and a second layer, an acoustic resistance layer is arranged between the first layer and the second layer, the inner edge of the acoustic resistance layer is positioned at the inner side of the boundary of the acoustic mirror in the horizontal direction, and the acoustic resistance of the acoustic resistance layer is different from that of the piezoelectric layer; and the material of the first layer is different from the material of the second layer. The invention also relates to a bulk acoustic wave resonator assembly, a method for adjusting the electromechanical coupling coefficient of a bulk acoustic wave resonator, a method for adjusting the electromechanical coupling coefficient difference value of a resonator in a bulk acoustic wave resonator assembly, a filter and an electronic device.

Description

Bulk acoustic wave resonator, bulk acoustic wave resonator assembly, electromechanical coupling coefficient difference adjusting method, filter, and electronic device

Technical Field

Embodiments of the present invention relate to the field of semiconductors, and in particular, to a bulk acoustic wave resonator and a component thereof, a method for adjusting an electromechanical coupling coefficient of a bulk acoustic wave resonator, a method for adjusting a difference value of electromechanical coupling coefficients of resonators in a bulk acoustic wave resonator component, a filter, and an electronic device.

Background

With the increasing development of 5G communication technology, the requirement on the data transmission rate is higher and higher. Corresponding to the data transmission rate is a high utilization of spectrum resources and spectrum complications. The complexity of the communication protocol imposes stringent requirements on the various performances of the rf system, and the rf filter plays a crucial role in the rf front-end module, which can filter out-of-band interference and noise to meet the signal-to-noise ratio requirements of the rf system and the communication protocol.

The traditional radio frequency filter is limited by structure and performance and cannot meet the requirement of high-frequency communication. As a novel MEMS device, a Film Bulk Acoustic Resonator (FBAR) has the advantages of small volume, light weight, low insertion loss, wide frequency band, high quality factor and the like, and is well suitable for the update of a wireless communication system, so that the FBAR technology becomes one of the research hotspots in the communication field.

The series resonators and parallel resonators of the prior art filter cooperate to form a filter passband characteristic. By setting the series resonance frequencies of the series resonators to be different from each other and the electromechanical coupling coefficient Kt of the series resonators²The roll-off characteristic on the right side of the filter passband can be effectively improved. Filter application Small Kt²While good roll-off characteristics are easily achieved for a resonator, once design criteria (bandwidth, insertion loss, out-of-band rejection, etc.) are determined, the Kt of the resonator²It is basically determined that such filter bandwidth and good roll-off characteristics of the filter are contradictory, that it is difficult to achieve good roll-off characteristics with a wide bandwidth filter design under a conventional architecture, and that Kt of a 50Ohm resonator is determined by a change in resonator structure under a condition that a resonator stack in a general filter has been determined²The change is only about +/-0.5%, and the improvement on the roll-off characteristic of the filter is limited. So as to release Kt between resonators²The limitation of the degree of freedom is beneficial to improving the roll-off performance of the whole filter.

Disclosure of Invention

The present invention has been made to mitigate or solve at least one of the above-mentioned problems in the prior art.

According to an aspect of an embodiment of the present invention, there is provided a bulk acoustic wave resonator including:

a substrate;

an acoustic mirror;

a bottom electrode;

a piezoelectric layer; and

a top electrode is arranged on the top of the substrate,

wherein:

the piezoelectric layer comprises a first layer and a second layer, an acoustic resistance layer is arranged between the first layer and the second layer, the inner edge of the acoustic resistance layer is positioned at the inner side of the boundary of the acoustic mirror in the horizontal direction, and the acoustic resistance of the acoustic resistance layer is different from that of the piezoelectric layer; and is

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

Embodiments of the present invention 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 a resonator as described above.

Embodiments of the present invention also relate to a method of adjusting an electromechanical coupling coefficient of 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 with an acoustic barrier layer disposed therebetween, the method comprising the steps of: the materials of the first layer and the second layer are made different to adjust the electromechanical coupling coefficient.

Embodiments of the present invention also relate to a method of adjusting the difference in electromechanical coupling coefficients of resonators within a bulk acoustic wave resonator assembly, said assembly comprising at least a first resonator and a second resonator, each 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, an acoustic resistance layer being arranged between the first layer and the second layer, the acoustic resistance layer having a different acoustic resistance than the piezoelectric layer, the method comprising the steps of: the materials of the first and second layers of the first and second resonators are selected to adjust the difference in the electromechanical coupling coefficients of the first and second resonators.

Embodiments of the invention also relate to a filter comprising a resonator or an assembly as described above.

Embodiments of the invention also relate to an electronic device comprising a filter as described above or a resonator as described above or an assembly as described above.

Drawings

These and other features and advantages of the various embodiments of the disclosed invention will be better understood from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate like parts throughout, and in which:

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

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

FIG. 3 illustrates a graph of the relationship between the width of an AW structure and the electromechanical coupling coefficient;

fig. 4 exemplarily shows a graph of the relationship between 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 AW is provided between the top electrode and the piezoelectric layer, respectively;

fig. 5A-5G schematically illustrate cross-sectional views of a process of fabricating the bulk acoustic wave resonator of fig. 2.

Detailed Description

The technical scheme of the invention is further specifically described by the following embodiments and the accompanying drawings. In the specification, the same or similar reference numerals denote the same or similar components. The following description of the embodiments of the present invention with reference to the accompanying drawings is intended to explain the general inventive concept of the present invention and should not be construed as limiting the invention. Some, but not all embodiments of the invention are described. All other embodiments that can be derived by one of ordinary skill in the art from the embodiments given herein are intended to be within the scope of the present invention.

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

10: the substrate can be selected from monocrystalline silicon, gallium nitride, gallium arsenide, sapphire, quartz, silicon carbide, diamond and the like.

20: the acoustic mirror can be a cavity, and a Bragg reflection layer and other equivalent forms can also be adopted. The embodiment of the present invention takes the form of a cavity.

20A: a release channel communicating therelease aperture 90 with the acoustic mirror cavity.

21: a sacrificial layer, in the case of the acoustic mirror in the form of a cavity, is provided in the cavity during the fabrication of the resonator, and is released in a later process to form the acoustic mirror cavity, thesacrificial layer 21 being optionally of silicon dioxide, doped silicon dioxide, polysilicon, amorphous silicon or the like.

30: the bottom electrode (including the bottom electrode pin) can be made of molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or a composite of the metals or an alloy thereof.

41: the first piezoelectric layer, which may be a single crystal piezoelectric material, may be selected, for example: the material may be polycrystalline piezoelectric material (corresponding to single crystal, non-single crystal material), optionally, polycrystalline aluminum nitride, zinc oxide, PZT, or a rare earth element doped material containing 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), erbium (Ho), erbium (holmium), thulium (Tm), ytterbium (Yb), lutetium (Lu), or the like.

42: the second piezoelectric layer, whose material is different from that of the first piezoelectric layer, may be a single crystal piezoelectric material, and may be selected, for example: the material may be polycrystalline piezoelectric material (corresponding to single crystal, non-single crystal material), optionally, polycrystalline aluminum nitride, zinc oxide, PZT, or a rare earth element doped material containing 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), erbium (Ho), erbium (holmium), thulium (Tm), ytterbium (Yb), lutetium (Lu), or the like.

50: the top electrode (including the top electrode pin) can be made of molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or a composite of the metals or an alloy thereof.

70: a passivation layer or process layer, which may be aluminum nitride, silicon dioxide, or the like.

80: an acoustic resistance layer having an acoustic resistance different from the acoustic resistance of the firstpiezoelectric layer 41 and the secondpiezoelectric layer 42. In the illustrated embodiment of the invention, in the form of an air gap (i.e., AW), but may also be in the form of a solid dielectric layer, such as silicon dioxide or a dopant thereof, or silicon nitride or a dopant thereof. As can be appreciated, the acoustic resistance of the acoustic resistance layer can also be greater than the acoustic resistance of the first piezoelectric layer and the second piezoelectric layer.

81: and the sacrificial layer is arranged at a position corresponding to the air gap in the process of preparing the resonator under the condition that the acoustic resistance layer is the air gap, and is released in the subsequent process to form the air gap, and thesacrificial layer 81 can be made of materials such as silicon dioxide, doped silicon dioxide, polysilicon and amorphous silicon.

90: a release hole.

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

In fig. 1-2, the bulk acoustic wave resonator comprises asubstrate 10, anacoustic mirror cavity 20 disposed in thesubstrate 10, abottom electrode 30, atop electrode 50 and piezoelectric layers comprising a firstpiezoelectric layer 41 and a secondpiezoelectric layer 42. Between the first and second piezoelectric layers there is arranged anacoustic barrier layer 80 in the form of an air gap. The passivation layer 70 is also shown in fig. 1-2.

Fig. 4 exemplarily shows a relationship between the width of the AW structure and the parallel resonance impedance of the bulk acoustic wave resonator in a case where the AW structure is provided in the piezoelectric layer and in a case where AW is provided between the top electrode and the piezoelectric layer, respectively. In fig. 4, the abscissa is the width of the AW structure (in μm) and the ordinate is the parallel resonant impedance Rp of the resonator (in ohms). In fig. 4, 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. 4, the value of the parallel resonance impedance of the AW structure in the piezoelectric layer is significantly higher than the value of the parallel resonance impedance of the AW structure between the piezoelectric layer and the top electrode. It can be seen that by providing theacoustic resistance layer 80 between the firstpiezoelectric layer 41 and the secondpiezoelectric layer 42, the performance of the resonator can be effectively improved relative to providing an acoustic resistance layer between the top electrode and the piezoelectric layers.

By providing theacoustic resistance layer 80 between the firstpiezoelectric layer 41 and the secondpiezoelectric layer 42, the value of the electromechanical coupling coefficient of the resonator can also be adjusted. Since the firstpiezoelectric layer 41 and the secondpiezoelectric layer 42 are separately prepared, the two piezoelectric layers can be prepared as different materials, and thus the electromechanical coupling coefficient of the resonator can be freely adjusted. For example, the firstpiezoelectric layer 41 is a piezoelectric layer of a certain material (e.g., one of aluminum nitride, zinc oxide, lead zirconate titanate, lithium niobate, quartz, potassium niobate, and lithium tantalate), and the secondpiezoelectric layer 42 is a doped layer doped with at least one rare earth element as mentioned above in the same material layer as the firstpiezoelectric layer 41, and in a specific embodiment, the firstpiezoelectric layer 41 and the secondpiezoelectric layer 42 are both aluminum nitride based piezoelectric materials, but one of the layers is a piezoelectric material without any doping, and the other layer is a piezoelectric material doped with scandium. For another example, the first piezoelectric layer and the second piezoelectric layer are doped layers of the same material, except that the doping concentration of the first piezoelectric layer is different from the doping concentration of the second piezoelectric layer, and in a specific embodiment, the firstpiezoelectric layer 41 and the secondpiezoelectric layer 42 are both made of a piezoelectric material based on aluminum nitride doped with scandium, and only the doping concentrations of the first piezoelectric layer and the second piezoelectric layer are different. As another example, the material of the firstpiezoelectric layer 41 is one of aluminum nitride, zinc oxide, lead zirconate titanate, lithium niobate, quartz, potassium niobate, and lithium tantalate, while the material of the secondpiezoelectric layer 42 is different from the material of the first piezoelectric layer, such as aluminum nitride, zinc oxide, lead zirconate titanate, lithium niobate, quartz, potassium niobate, and lithium tantalate.

Therefore, in the invention, the AW structure is arranged in the piezoelectric layer to improve the performance of the resonator, and different piezoelectric layers can be prepared on the upper side and the lower side of the AW structure to realize the free setting of the electromechanical coupling coefficient of the resonator.

The above arrangement of differently doped

piezoelectric layers

41 and 42 allows a large amplitude adjustment of the electromechanical coupling coefficient of the resonator. For example, when a duplexer is manufactured in the same Die, it is necessary to have a large difference (greater than 1%) between the electromechanical coupling coefficients of the resonators in the transmit filter Tx and the electromechanical coupling coefficients of the resonators in the receive filter Rx, but it is necessary to have a small difference (less than 1%) between the electromechanical coupling coefficients of the different resonators in the transmit filter Tx or the receive filter Rx, at this time, the width of the AW structure in the effective area of the resonators may be adjusted, that is, the electromechanical coupling coefficients of the resonators in the filter may be adjusted by adjusting the widths L1 and L2 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 distance in the horizontal direction between the non-electrode connection end of the top electrode and the inner edge of the AW structure; 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 of the acoustic mirror boundary from the inner edge of the AW structure at the connection end of the top electrode. In one embodiment of the present invention, L1 and L2 may be the same or different, but are each in the range of 0.25-10 μm.

Fig. 3 illustrates a graph of the relationship between the width of the AW structure or air gap and the electromechanical coupling coefficient. In fig. 3, the abscissa is the width of the AW structure (in μm) and the ordinate is the electromechanical coupling coefficient. Fig. 3 shows the effect of the width of the AW structure of the resonator on the electromechanical coupling coefficient when the width of the AW structure is the same on each side of the active area of the resonator, which coefficient decreases progressively with increasing AW width as shown in fig. 3. It can be seen that the electromechanical coupling coefficient of the resonator can be adjusted by adjusting the width of the AW structure.

For resonators with polygonal active areas, the width of the AW structure may be the same or different for each side.

In the present invention, the AW structure, the acoustic resistance layer, or the air gap is disposed at the non-electrode connection end of the top electrode, and when the active area of the resonator is polygonal, the case of disposing only one or more sides of the non-electrode connection end may be included, and the case of disposing all sides of the non-electrode connection end may be included. In the present invention, the AW structure, the acoustic resistance layer, or the 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 polygonal, it means that the AW structure, the acoustic resistance layer, or the air gap is provided at the side where the electrode connection end of the top electrode is located. The AW structure or the acoustic barrier layer or the air gap can also be arranged around the entire active area of the resonator.

When the thickness of the piezoelectric layer is constant, and the same piezoelectric material is adopted on the upper side and the lower side of the AW structure, the electromechanical coupling coefficient of the resonator is a determined value under the same condition no matter the AW structure is arranged at any position in the piezoelectric layer. However, when different piezoelectric layer materials are used for the upper and lower sides of the AW structure, the degree of freedom in designing the electromechanical coupling coefficient of the resonator can be increased. For example, the firstpiezoelectric layer 41 is made of an undoped aluminum nitride material, and the secondpiezoelectric layer 42 is made of a scandium-doped aluminum nitride material. For example, the electromechanical coupling coefficient of a piezoelectric layer using undoped aluminum nitride alone is 6% when the piezoelectric layer is of a fixed thickness, and the electromechanical coupling coefficient of a piezoelectric layer using doped aluminum nitride alone is 10%. Therefore, when the thickness of the piezoelectric layers is not changed, the electromechanical coupling coefficient of the resonator is freely changed between 6% and 10% by controlling the doping concentration of the firstpiezoelectric layer 41 and the secondpiezoelectric layer 42. After the thicknesses of the two piezoelectric layers are respectively determined, the electromechanical coupling coefficients of different resonators in the filter can be finely adjusted by controlling the change of the width of the AW structure, so that the design freedom degree of the electromechanical coupling coefficients of the resonators in the filter can be improved to the maximum extent.

In the invention, the electromechanical coupling coefficients of the resonators can be adjusted by selecting the materials of the first piezoelectric layer and the second piezoelectric layer, and the difference between the electromechanical coupling coefficients of the two resonators can be changed between 0% and 10% in the manner.

In fig. 2, the materials of the firstpiezoelectric layer 41 and the secondpiezoelectric layer 42 are different, and when the thicknesses of the firstpiezoelectric layer 41 and the secondpiezoelectric layer 42 are fixed, for a certain electromechanical coupling coefficient of the resonator, the required electromechanical coupling coefficient can be achieved by changing the materials of the piezoelectric layers. After the doping or material determination of the firstpiezoelectric layer 41 and the secondpiezoelectric layer 42, the electromechanical coupling coefficient of the resonator can be further adjusted by changing the widths of the widths L1 and L2 in fig. 2.

Also shown in fig. 2 are the thicknesses of the firstpiezoelectric layer 41 and the secondpiezoelectric layer 42, which are H1 and H2, respectively. The ratio of the two different piezoelectric materials can be adjusted by adjusting the ratio of H1 and H2, so that the electromechanical coupling coefficient of the resonator can be adjusted. Similarly, when H2 and H1 are determined, 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 where the AW structure is sandwiched between the firstpiezoelectric layer 41 and the secondpiezoelectric layer 42 is not fixed. In one embodiment of the invention, the lower surface of the AW structure is spaced further from the lower surface of the firstpiezoelectric layer 41 than the lower surface of the AW structure

The upper surface of the AW structure is also spaced from the secondpiezoelectric layer 42 by a greater distance than

The thickness of the AW structure is in the range

The following exemplifies a process of manufacturing the bulk acoustic wave resonator in fig. 2 with reference to fig. 5A to 5G.

First, as shown in fig. 5A, a cavity is formed as theacoustic mirror 20 on the upper surface of thesubstrate 10, then a sacrificial material is provided on the upper surface of thesubstrate 10, the sacrificial material fills the cavity, and then the sacrificial material on the upper surface of thesubstrate 10 is removed by a CMP (chemical mechanical polishing) process and the upper surface of the sacrificial material in the cavity is made flush with the upper surface of thesubstrate 10 to form asacrificial layer 21.

Second, as shown in FIG. 5B, a layer of electrode material is deposited and patterned over the structure of FIG. 5A to form thebottom electrode 30.

Third, as shown in fig. 5C, a firstpiezoelectric layer 41, which may be, for example, an undoped piezoelectric layer, is deposited on the structure of fig. 5B.

Fourth, as shown in fig. 5D, a sacrificial material is deposited and patterned on the upper surface of the firstpiezoelectric layer 41 of fig. 5C to form asacrificial layer 81. Thesacrificial layer 81 will be released at a later stage for forming theAW structure 80.

Fifth, as shown in fig. 5E, a secondpiezoelectric layer 42, which may be, for example, a doped piezoelectric layer, is deposited on the upper surface of the structure of fig. 5D.

Sixth, as shown in fig. 5F, atop electrode 50 and a protective or passivation layer 70 are prepared on the upper surface of the structure of fig. 5E.

Seventh, thesacrificial layer 21 and thesacrificial layer 81 are released to form theacoustic mirror 20 and theAW structure 80, respectively, as shown in fig. 5G.

It is to be noted that, in the present invention, each numerical range, except when explicitly indicated as not including the end points, can be either the end points or the median of each numerical range, and all fall within the scope of the present invention.

In the present invention, the upper and lower are with respect to the bottom surface of the substrate, and for a component, the side thereof close to the bottom surface is the lower side, and the side thereof far from the bottom surface is the upper side.

In the present invention, the inner and outer are in the lateral direction or the radial direction with respect 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), the side or end of a component close to the center of the effective area is the inner side or the inner end, and the side or end of the component away from the center of the effective area is the outer side or the outer end. For a reference position, being inside of the position means being between the position and the center of the effective area in the lateral or radial direction, and being outside of the position means being further away from the center of the effective area than the position in the lateral or radial direction.

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 invention provides the following technical scheme:

1. a bulk acoustic wave resonator comprising:

a substrate;

an acoustic mirror;

a bottom electrode;

a piezoelectric layer; and

a top electrode is arranged on the top of the substrate,

wherein:

2. The resonator ofclaim 1, wherein:

the acoustic resistance layer comprises a non-connection end acoustic resistance layer at a non-electrode connection end of the top electrode, and the inner edge of the non-connection end acoustic resistance layer is located on the inner side of the non-electrode connection end of the top electrode in the horizontal direction.

3. The resonator ofclaim 2, wherein:

the non-electrode connecting end of the top electrode is positioned at 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, a first distance exists 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 mu m.

4. The resonator of any of claims 1-3, wherein:

the acoustic barrier layer includes a connection end acoustic barrier layer at an electrode connection end of the top electrode.

5. The resonator ofclaim 4, wherein:

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

6. The resonator ofclaim 1, wherein:

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

7. The resonator ofclaim 1, wherein:

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

8. The resonator of any of claims 1-7, wherein:

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

The first layer and the second layer are doped layers made of the same material, and the doping concentration of the first layer is different from that of the second layer.

9. The resonator of any of claims 1-7, wherein:

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

10. 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 of claims 1-9.

11. The assembly ofclaim 10, wherein:

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

the first resonator and the second resonator are both resonators as described in any of the claims 1-9.

12. The assembly of claim 11, wherein:

the first resonator and the second resonator are resonators as described in 8 or 9.

13. The assembly of claim 12, 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%.

14. The assembly of any one of claims 10-13, wherein:

the first resonator and the second resonator are both resonators according to 3 or 5;

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.

15. A method of adjusting an electromechanical coupling coefficient of 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 with an acoustic barrier layer disposed therebetween, the method comprising the steps of:

the materials of the first layer and the second layer are made different to adjust the electromechanical coupling coefficient.

16. The method of claim 15, further comprising the step of:

the heights of the first layer and the second layer are adjusted to adjust the electromechanical coupling coefficient.

17. The method of claim 15 or 16, further comprising the step of:

adjusting the width of the acoustic resistance layer to further adjust the electromechanical coupling coefficient, wherein: the width of the acoustic resistance layer is the distance between the non-electrode connecting end of the top electrode and the inner edge of the acoustic resistance layer in the horizontal direction if the width of the acoustic resistance layer is at the non-electrode connecting end of the top electrode, and is the distance between the boundary of the acoustic mirror and the inner edge of the acoustic resistance layer in the horizontal direction if the width of the acoustic resistance layer is at the electrode connecting end of the top electrode.

18. A method of adjusting differences in electromechanical coupling coefficients of resonators in a bulk acoustic wave resonator assembly, the assembly comprising at least a first resonator and a second resonator, each 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, an acoustic resistance layer being provided between the first and second layers, the acoustic resistance of the acoustic resistance layer being different from the acoustic resistance of the corresponding piezoelectric layer, the method comprising the steps of:

the materials of the first and second layers of the first and second resonators are selected to adjust the difference in the electromechanical coupling coefficients of the first and second resonators.

19. The method of claim 18, further comprising the steps of:

and adjusting the heights of the first layer and the second layer of the first resonator and/or the second resonator so as to adjust the difference of the electromechanical coupling coefficients of the first resonator and the second resonator.

20. The method of claim 18 or 19, wherein:

the assembly comprises a first filter comprising the first resonator and a second filter comprising the second resonator;

the method comprises the following steps: the materials of the first and second layers of resonators within the first filter and the materials of the first and second layers of resonators within the second filter are selected to adjust a difference between an electromechanical coupling coefficient of a resonator within the first filter and an electromechanical coupling coefficient of a resonator within the second filter.

21. The method of 20, further comprising the steps of:

adjusting the width of the acoustically resistive layer of the resonators in the first filter to further adjust the difference in electromechanical coupling coefficients between different resonators in the first filter, and/or adjusting the width of the acoustically resistive layer in the second filter to further adjust the difference in electromechanical coupling coefficients between different resonators in the second filter,

wherein: the width of the acoustic resistance layer is the distance between the non-electrode connecting end of the top electrode and the inner edge of the acoustic resistance layer in the horizontal direction if the width of the acoustic resistance layer is at the non-electrode connecting end of the top electrode, and is the distance between the boundary of the acoustic mirror and the inner edge of the acoustic resistance layer in the horizontal direction if the width of the acoustic resistance layer is at the electrode connecting end of the top electrode.

22. A filter comprising a bulk acoustic wave resonator according to any one of claims 1-9, or a bulk acoustic wave resonator assembly according to any one of claims 10-14.

23. An electronic device comprising a filter according to 22, or a bulk acoustic wave resonator according to any one of claims 1-9, or a bulk acoustic wave resonator assembly according to any one of claims 10-14.

The electronic device includes, but is not limited to, intermediate products such as a radio frequency front end and a filtering and amplifying module, and terminal products such as a mobile phone, WIFI and an unmanned aerial vehicle.

Although embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.

Claims

1. A bulk acoustic wave resonator comprising:

a substrate;

an acoustic mirror;

a bottom electrode;

a piezoelectric layer; and

a top electrode is arranged on the top of the substrate,

wherein:

2. The resonator of claim 1, wherein:

3. The resonator of claim 2, wherein:

4. The resonator of any of claims 1-3, wherein:

5. The resonator of claim 4, wherein:

6. The resonator of claim 1, wherein:

7. The resonator of claim 1, wherein:

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

8. The resonator of any of claims 1-7, wherein:

9. The resonator of any of claims 1-7, wherein:

10. A bulk acoustic wave resonator assembly comprising:

11. The assembly of claim 10, wherein:

the first resonator and the second resonator are both resonators as claimed in any of claims 1-9.

12. The assembly of claim 11, wherein:

the first and second resonators are resonators as claimed in claim 8 or 9.

13. The assembly of claim 12, wherein:

14. The assembly of any one of claims 10-13, wherein:

-the first and second resonators are both resonators according to claim 3 or 5;

16. The method of claim 15, further comprising the step of:

17. The method according to claim 15 or 16, further comprising the step of:

19. The method of claim 18, further comprising the step of:

20. The method of claim 18 or 19, wherein:

21. The method of claim 20, further comprising the step of:

22. A filter comprising a bulk acoustic wave resonator according to any of claims 1-9, or a bulk acoustic wave resonator assembly according to any of claims 10-14.

23. An electronic device comprising a filter according to claim 22, or a bulk acoustic wave resonator according to any of claims 1-9, or a bulk acoustic wave resonator assembly according to any of claims 10-14.