CN114070224A - Bulk acoustic wave resonator assembly with acoustic decoupling layer, manufacturing method of bulk acoustic wave resonator assembly, filter and electronic device - Google Patents

Bulk acoustic wave resonator assembly with acoustic decoupling layer, manufacturing method of bulk acoustic wave resonator assembly, filter and electronic device Download PDF

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CN114070224A
CN114070224A CN202010785120.2A CN202010785120A CN114070224A CN 114070224 A CN114070224 A CN 114070224A CN 202010785120 A CN202010785120 A CN 202010785120A CN 114070224 A CN114070224 A CN 114070224A
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electrode
resonator
bottom electrode
assembly
top electrode
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庞慰
张巍
张孟伦
郝龙
徐洋
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ROFS Microsystem Tianjin Co Ltd
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ROFS Microsystem Tianjin Co Ltd
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Priority to PCT/CN2021/110251 priority patent/WO2022028401A1/en
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
    • H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
    • H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/02007—Details of bulk acoustic wave devices
    • H03H9/02086—Means for compensation or elimination of undesirable effects
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/02007—Details of bulk acoustic wave devices
    • H03H9/02157—Dimensional parameters, e.g. ratio between two dimension parameters, length, width or thickness
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
    • H03H9/205—Constructional features of resonators consisting of piezoelectric or electrostrictive material having multiple resonators
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/46—Filters
    • H03H9/48—Coupling means therefor
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/46—Filters
    • H03H9/54—Filters comprising resonators of piezo-electric or electrostrictive material
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
    • H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
    • H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
    • H03H2003/025—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks the resonators or networks comprising an acoustic mirror
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
    • H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
    • H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
    • H03H2003/028—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks for obtaining desired values of other parameters

Abstract

The invention relates to a bulk acoustic wave resonator assembly comprising: a substrate; at least two resonators which are bulk acoustic wave resonators and are stacked in a thickness direction of the substrate on one side of the substrate, the at least two resonators including a first resonator and a second resonator, the second resonator being above the first resonator, the first resonator having a first top electrode, a first piezoelectric layer, a first bottom electrode and a first acoustic mirror, the second resonator having a second top electrode, a second piezoelectric layer, a second bottom electrode and a second acoustic mirror, wherein: an acoustic decoupling layer in the form of a cavity is arranged between the first top electrode and the second bottom electrode, and the acoustic decoupling layer serves as the second acoustic mirror. The invention also relates to a method of manufacturing a bulk acoustic wave resonator assembly, a filter and an electronic device.

Description

Bulk acoustic wave resonator assembly with acoustic decoupling layer, manufacturing method of bulk acoustic wave resonator assembly, 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 assembly and a method of manufacturing the same, a filter having the resonator assembly, and an electronic device.
Background
With the rapid development of wireless communication technology, the application of miniaturized portable terminal equipment is becoming more and more extensive, and thus the demand for high-performance and small-size radio frequency front-end modules and devices is becoming more and more urgent. In recent years, filter devices such as filters and duplexers based on Film Bulk Acoustic Resonators (FBARs) have been increasingly favored in the market. On one hand, the material has excellent electrical properties such as low insertion loss, steep transition characteristic, high selectivity, high power capacity, strong anti-static discharge (ESD) capability and the like, and on the other hand, the material has the characteristics of small volume and easy integration.
However, there is a real need for further reduction of the size of the filter device.
In addition, in the prior art, bulk acoustic wave resonators are combined in series and parallel to form a filter, and a plurality of resonators are required to be formed on a substrate, and the resonators are separated at different horizontal positions of the substrate and connected by horizontal metal leads, as shown in fig. 1, wherein the top electrode 104 of the resonator 100 within the dashed box is connected to the bottom electrode 102 of the resonator 200 through the conductive via 10, in order to ensure the electrical signal transmission and the limitation of the manufacturing process, the connection width of the conductive via 10 and the top electrode 104 of the resonator 100, the width of the conductive via 10, the width of the top electrode 104 of the resonator 100 and the width of the bottom electrode 102 of the resonator 200 are required, and the total length is generally greater than 5 μm, which causes the connection line to introduce large electrical loss, especially for high-frequency resonators, at electrode thicknesses <1000A, the insertion loss is degraded by more than 0.1 dB.
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 assembly including:
a substrate;
at least two resonators which are bulk acoustic wave resonators and are stacked in a thickness direction of the substrate on one side of the substrate, the at least two resonators including a first resonator and a second resonator, the second resonator being above the first resonator, the first resonator having a first top electrode, a first piezoelectric layer, a first bottom electrode and a first acoustic mirror, the second resonator having a second top electrode, a second piezoelectric layer, a second bottom electrode and a second acoustic mirror,
wherein:
an acoustic decoupling layer in the form of a cavity is arranged between the first top electrode and the second bottom electrode, and the acoustic decoupling layer serves as the second acoustic mirror.
The embodiment of the invention also relates to a bulk acoustic wave resonator assembly, which comprises at least two resonators adjacently stacked from bottom to top in the thickness direction of the assembly, wherein the at least two resonators are bulk acoustic wave resonators, the at least two resonators comprise a first resonator and a second resonator, an acoustic decoupling layer in a cavity form is arranged between a top electrode of the first resonator and a bottom electrode of the second resonator, and the acoustic decoupling layer is used as an acoustic mirror of the second resonator.
Embodiments of the present invention also relate to a method of manufacturing a bulk acoustic wave resonator assembly, comprising:
step 1: forming a first structure for a first bulk acoustic wave resonator on a surface of a substrate, the first bulk acoustic wave resonator comprising a first acoustic mirror, a first bottom electrode, a first piezoelectric layer, a first top electrode;
step 2: arranging a patterned sacrificial material layer on the first structure formed in the step 1;
and step 3: forming a second structure for a second bulk acoustic wave resonator on the structure of step 2, the second bulk acoustic wave resonator including a second acoustic mirror, a second bottom electrode, a second piezoelectric layer, and a second top electrode, the sacrificial material layer being located between the first top electrode and the second bottom electrode in a thickness direction of the substrate;
and 4, step 4: releasing the sacrificial material layer to form a cavity constituting a second acoustic mirror of a second bulk acoustic wave resonator.
Embodiments of the present invention are also directed to a filter comprising the bulk acoustic wave resonator assembly described above.
Embodiments of the invention also relate to an electronic device comprising a filter as described above or a resonator 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 cross-sectional view of an electrical connection between two adjacent bulk acoustic wave resonators in a prior art design;
FIG. 2 is a schematic top view of a bulk acoustic wave resonator assembly according to an exemplary embodiment of the present invention;
figure 3A is a schematic cross-sectional view of a bulk acoustic wave resonator taken along line a-a' in figure 2, according to an exemplary embodiment of the present invention;
FIG. 3B is a schematic cross-sectional view of a bulk acoustic wave resonator taken along line B-B' of FIG. 2, according to an exemplary embodiment of the present invention;
figure 3C is a schematic cross-sectional view of a bulk acoustic wave resonator taken along line C-C' in figure 2, in accordance with an exemplary embodiment of the present invention;
FIG. 3D is a graph illustrating a comparison of insertion loss curves for the structure of FIG. 3A relative to the structure of FIG. 1;
3E-3G are schematic cross-sectional views of a bulk acoustic wave resonator taken along line A-A' in FIG. 2 showing electrodes defining a common cavity having an outwardly convex shape relative to the common cavity, in accordance with various embodiments of the present invention;
fig. 4A is a schematic cross-sectional view of the bulk acoustic wave resonator taken along line a-a' in fig. 2, in which a portion of the non-electrode connection end of the bottom electrode of the upper resonator in the circumferential direction is electrically connected to the non-electrode connection end of the top electrode of the lower resonator, according to an exemplary embodiment of the present invention;
fig. 4B is a schematic cross-sectional view of the bulk acoustic wave resonator taken along line B-B' in fig. 2, in which an electrode connection terminal of the bottom electrode of the upper resonator is electrically connected to an electrode connection terminal of the top electrode of the lower resonator, according to an exemplary embodiment of the present invention;
fig. 5A is a schematic cross-sectional view of a bulk acoustic wave resonator taken along line a-a' in fig. 2, in which a non-electrode connecting end of a bottom electrode of an upper resonator is not electrically connected to a non-electrode connecting end of a top electrode of a lower resonator, an end of the non-electrode connecting end of the bottom electrode of the upper resonator being disposed on an upper surface of a piezoelectric layer of the lower resonator, according to an exemplary embodiment of the present invention;
fig. 5B is a schematic cross-sectional view of the bulk acoustic wave resonator taken along line a-a' in fig. 2, in which the non-electrode connecting end of the bottom electrode of the upper resonator is not electrically connected to the non-electrode connecting end of the top electrode of the lower resonator, an end of a part of the non-electrode connecting end of the bottom electrode of the upper resonator is disposed on an upper surface of the piezoelectric layer of the lower resonator and an end of the other part is located inside a boundary of the common cavity in a lateral direction, according to an exemplary embodiment of the present invention;
figure 5C is a schematic cross-sectional view of a bulk acoustic wave resonator taken along line C-C' in figure 2, in accordance with an exemplary embodiment of the present invention;
6A-6C are cross-sectional schematic views of a bulk acoustic wave resonator assembly according to various embodiments of the present invention showing a cavity between the bottom electrode of the upper resonator and the top electrode of the lower resonator and a support disposed thereon;
FIGS. 7A-7E are schematic diagrams illustrating a fabrication process for the structure shown in FIG. 3A;
FIGS. 8A and 8B illustrate a schematic structural view of a method of making the support of FIGS. 6A-6C;
FIG. 9 is a schematic cross-sectional view of a bulk acoustic wave resonator assembly according to an exemplary embodiment of the present invention;
fig. 10 is a cross-sectional view of a resonator assembly in which upper and lower resonator active areas are acoustically isolated by a cavity, and the upper and lower resonators are electrically isolated from each other in a left side view of fig. 10 and are electrically connected to each other in a right side view of fig. 10, according to an exemplary embodiment of the present invention.
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.
The reference numerals in the present invention are explained as follows:
11: and the electrode of the bottom electrode of the lower resonator is led out.
12: and the electrode of the top electrode of the lower resonator is led out.
13: and the electrode of the bottom electrode of the upper resonator is led out.
14: the electrode of the top electrode of the upper resonator is led out. The above electrode pair outer leads 11 to 14 are connected to the corresponding electrodes,
s: the substrate can be selected from monocrystalline silicon, gallium nitride, gallium arsenide, sapphire, quartz, silicon carbide, diamond and the like.
101,201: the acoustic mirror 101 may be a cavity, and a bragg reflector or other equivalent forms may be used. The acoustic mirror 201 employs a cavity, which constitutes an acoustic decoupling layer.
102,202: the bottom electrode is made of molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or their composite or their alloy.
103,203: the piezoelectric layer can be a single crystal piezoelectric material, and can be selected from the following: 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.
104,204: the top electrode can be made of the same material as the bottom electrode, and the material can be selected from molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or the composite of the above metals or the alloy thereof, and the like. The top and bottom electrode materials are typically the same, but may be different.
105,205: the passivation layer is typically a dielectric material such as silicon dioxide, aluminum nitride, silicon nitride, etc.
Fig. 2 is a schematic top view of a bulk acoustic wave resonator assembly according to an exemplary embodiment of the present invention, in fig. 2, a line a-a ' corresponds to a section passing through non-electrode connection ends of top electrodes of upper and lower resonators and a non-electrode connection end of a bottom electrode, a line B-B ' corresponds to a section passing through an electrode connection end of a bottom electrode of a lower resonator and an electrode connection end of a top electrode of a lower resonator, and a line C-C ' corresponds to a section passing through an electrode connection end of a bottom electrode of an upper resonator and an electrode connection end of a top electrode of an upper resonator.
Fig. 3A is a schematic cross-sectional view of a bulk acoustic wave resonator taken along line a-a' in fig. 2 according to an exemplary embodiment of the present invention.
Although not shown, the top electrode of the resonator may also have a process layer disposed thereon, which may cover the top electrode, and which may function as a mass tuning load or passivation layer. The passivation layer may be made of dielectric material, such as silicon dioxide, aluminum nitride, silicon nitride, etc.
Further, in the structure shown in fig. 3A, two resonators are formed at the same horizontal position of the substrate S, and the two resonators are different in spatial position in the vertical direction or in the thickness direction of the substrate.
As can be appreciated by those skilled in the art, three resonators or more may also be stacked. Figure 9 is a schematic cross-sectional view of a bulk acoustic wave resonator assembly according to an exemplary embodiment of the present invention. As shown in fig. 9, the resonator assembly includes a first resonator, a second resonator, and a third resonator stacked in the thickness direction, an acoustic decoupling layer 201 (a cavity in this embodiment) is provided between a top electrode 104 of the first resonator and a bottom electrode 202 of the second resonator, an acoustic decoupling layer 301 (a cavity in this embodiment) is provided between a top electrode 204 of the second resonator and a bottom electrode 302 of the third resonator, and the acoustic decoupling layer 301 constitutes an acoustic mirror of the third resonator. Optionally, as shown in fig. 9, the boundary of the acoustic decoupling layer 301 is outside the boundary of the acoustic decoupling layer 201 in the horizontal direction. As can be appreciated, the assembly structures shown in other embodiments of the invention may also be stacked.
In the structure shown in fig. 3A, two resonators above and below are shown, wherein the effective area of the upper resonator is the overlapping area of the top electrode 204, the piezoelectric layer 203, the bottom electrode 202, and the cavity 201 in the thickness direction. The lower resonator is an overlapping area of the cavity 201, the top electrode 104, the piezoelectric layer 103, the bottom electrode 102, and the acoustic mirror 101 in the thickness direction.
Accordingly, in fig. 9, the effective area of the uppermost third resonator is the overlapping area of the top electrode 304, the piezoelectric layer 303, the bottom electrode 302, and the cavity 301 in the thickness direction, the effective area of the middle second resonator is the overlapping area of the cavity 301, the top electrode 204, the piezoelectric layer 203, the bottom electrode 202, and the cavity 201 in the thickness direction, and the effective area of the lowermost first resonator is the overlapping area of the cavity 201, the top electrode 104, the piezoelectric layer 103, the bottom electrode 102, and the cavity 101 in the thickness direction.
In the structure shown in fig. 3A, the upper resonator is acoustically separated from the lower resonator by a cavity 201, i.e. the cavity 201 constitutes an acoustic decoupling layer between the upper and lower resonators, thereby completely avoiding the acoustic coupling problem that may result from the adjacent stacking of the upper and lower resonators.
The cavity 201 is used as an acoustic decoupling layer, complete acoustic decoupling of the upper resonator and the lower resonator can be achieved, and therefore the performance of the resonators is better. Further, in the case where the cavity 201 is directly surrounded by the top electrode 104 of the lower resonator and the bottom electrode 202 of the upper resonator (the structure defining the position of the cavity in other embodiments further includes the piezoelectric layer of the upper resonator and/or the lower resonator), such as the structures shown in fig. 3A to 3C, 3E to 3G, and 9, the overall structure is stable and reliable, and the manufacturing process is simple.
As can be understood by those skilled in the art, the cavity 201 is disposed between the bottom electrode of the upper resonator and the top electrode of the lower resonator in the thickness direction of the resonator, including not only the case where at least a portion of the upper and lower boundaries of the cavity is defined by the lower surface of the bottom electrode of the upper resonator and the upper surface of the top electrode of the lower resonator, but also the case where the upper surface of the top electrode of the lower resonator is provided with a process layer (e.g., a passivation layer) such that the process layer defines at least a portion of the lower boundary of the cavity 201. These are all within the scope of the present invention.
In the structure shown in fig. 3A, since the plurality of resonators are formed at the same horizontal position of the substrate S, the spatial positions of the plurality of resonators in the vertical direction or in the thickness direction of the substrate are different, and therefore, the area of the filter can be greatly reduced, for example, in the case where two resonators are provided as well, from the area P1 shown in fig. 1 to the area P2 shown in fig. 3A.
As shown in fig. 3A, the bottom electrode 202 of the upper resonator and the top electrode 104 of the lower resonator are electrically connected to each other at a non-electrode connection terminal. Under the condition that the bottom electrode of the upper resonator is directly connected with the top electrode of the lower resonator, the bottom electrode of the upper resonator is directly and electrically connected with the top electrode of the lower resonator, and the length of the connecting part is shortened compared with that in the figure 1, namely, the transmission path is shortened, and the transmission loss is reduced; in addition, the transmission loss of the electrical signal output is further reduced by the sum of the thicknesses of the top electrode of the lower resonator and the bottom electrode of the upper resonator through the metal thickness. By reducing the electrical losses, the insertion loss of the final filter is optimized. As shown in fig. 3A, the length of the transmission path formed by the bottom electrode of the upper resonator and the top electrode of the lower resonator at the non-electrode-connecting end is d, which may be less than 5 μm.
With the structure of fig. 3A to 3C, for example, since the current transmission path to the lower resonator becomes short, for example, can be less than 5 μm, the transmission loss is reduced, and the thickness of the top electrode 104 of the lower resonator and the thickness of the bottom electrode 202 of the upper resonator can be thinned, which is advantageous for further miniaturization of the resonator. In the case where the bottom electrode of the upper resonator and the top electrode of the lower resonator are electrically connected to each other, the electrode film thickness of the bottom electrode of the upper resonator and the top electrode of the upper resonator can be further reduced simultaneously while reducing the circuit transmission path loss to the bottom electrode of the upper resonator and the current transmission path loss to the top electrode of the lower resonator. Accordingly, in the case where the resonance frequency of the lower resonator is greater than 0.5GHz, the thickness of the top electrode 104 is smaller than
Figure BDA0002621667080000071
And/or the thickness of the bottom electrode 202 is less than in the case where the resonance frequency of the upper resonator is greater than 0.5GHz
Figure BDA0002621667080000072
In a further embodiment, in the case where the resonance frequency of the lower resonator is more than 3GHz, the thickness of the top electrode 104 may be designed to be less than
Figure BDA0002621667080000073
And/or in case the resonance frequency of the upper resonator is larger than 3GHz, the thickness of the bottom electrode 202 of the upper resonator may also be smaller than
Figure BDA0002621667080000074
As can be understood, in the present invention, the thinning of the thickness of the electrode means thinning of the thickness of the electrode in the effective region of the resonator.
Fig. 3D is a graph schematically illustrating a comparison of insertion loss curves for the structure of fig. 3A with respect to the structure of fig. 1. Fig. 3D is a comparison between the insertion loss curve (solid line) of the 3.5G band using the structure of fig. 3A of the present invention and the insertion loss curve (dotted line) of the conventional structure of fig. 1, and it can be seen that the insertion loss is improved by about 0.1dB due to the reduction of the electrode loss using the structure of fig. 3A of the present invention.
Fig. 3B is a schematic cross-sectional view of the bulk acoustic wave resonator taken along line B-B 'in fig. 2 according to an exemplary embodiment of the present invention, and fig. 3C is a schematic cross-sectional view of the bulk acoustic wave resonator taken along line C-C' in fig. 2 according to an exemplary embodiment of the present invention. It can be seen that in fig. 3B and 3C, the top electrode of the lower resonator is electrically connected to the bottom electrode of the upper resonator in the circumferential direction around the entire cavity 201.
In the case where the bottom electrode of the upper resonator and the top electrode of the lower resonator are electrically connected to each other, in the structure shown in fig. 3A to 3C, the non-electrode connection end and the electrode connection end of the bottom electrode of the upper resonator and the top electrode of the lower resonator are connected to each other, that is, the electrical connection is formed around the entire circumference of the cavity 201. However, other connection means than the one shown in fig. 3A-3C are possible. For example, as described later with reference to fig. 4A, the bottom electrode of the upper resonator and the top electrode of the lower resonator may be electrically connected to each other only at a part of the non-electrode connection terminal; alternatively, as described with reference to fig. 4B, the bottom electrode of the upper resonator and the top electrode of the lower resonator may be electrically connected to each other only at the electrode connection end; or the bottom electrode of the upper resonator and the top electrode of the lower resonator may be electrically connected to each other only at all or part of the non-electrode connection terminals. These are all within the scope of the present invention.
The connection between the bottom electrode of the upper resonator and the top electrode of the lower resonator is not limited to the structures shown in fig. 3A-3C. Fig. 10 is a cross-sectional view of a resonator assembly in which upper and lower resonator active areas are acoustically isolated by a cavity, and the upper and lower resonators are electrically connected to each other in a right side view of fig. 10, according to an exemplary embodiment of the present invention.
As shown in the right sectional view of fig. 10, the piezoelectric layer 103 is covered with the top electrode 104, and the bottom electrode 202 is connected to the top electrode 104 at both the electrode connection end and the non-electrode connection end. In the right side view of fig. 10, the electrode connecting end of bottom electrode 202 overlaps the electrode connecting end of top electrode 104, and the non-electrode connecting end of bottom electrode 202 overlaps the non-electrode connecting end of top electrode 104.
Process or passivation layers 105 and 205, which may or may not be provided, are shown in fig. 10 as being provided on the top electrode upper surface.
In the structure shown in fig. 10 of the present invention, since the second electrode layer where the bottom electrode 202 is located covers the first electrode layer where the top electrode 104 is located, the metal thickness of the bottom electrode of the upper resonator and the top electrode of the lower resonator at the electrode connection portion can be increased, which is beneficial to reducing the electrical loss.
When the maximum width of the effective area of the resonator is larger than the height of the cavity, the upper resonator and the lower resonator may be contacted in the cavity due to bending and the like, for example, the height of the cavity is
Figure BDA0002621667080000081
When the maximum width of the resonator effective area is larger than 100 μm, in order to ensure the complete formation of the cavity 201 in the upper and lower resonator effective areas, the stress of the lower resonator can be controlled to bend towards the lower air cavity, and/or the stress of the upper resonator can be controlled to bend towards the upper air cavity, and the top electrode of the finally formed lower resonator is concave downwards, and/or the top electrode of the upper resonator is convex upwards. Fig. 3E-3G are schematic cross-sectional views of the bulk acoustic wave resonator taken along line a-a' in fig. 2 showing that the electrodes defining the cavity 201 have an outwardly convex shape with respect to the common cavity, in particular, fig. 3E is a schematic view of the lower resonator being bent downward, fig. 3F is a schematic view of the upper resonator being bent upward, and fig. 3G is a schematic view of the lower resonator being bent downward and the upper resonator being bent upward, according to various embodiments of the present invention. On the other hand, although the upper and lower resonators are bent by adjusting the stress of their respective films, the upper resonator film is prevented from contacting with the lower resonator film due to the small thickness of the upper and lower resonators and the mechanical contact of the upper and lower resonators at the edge of the acoustic decoupling layer in the form of a cavityThe stress of the lower resonator affects the working state and performance of the lower resonator to a certain degree, and the stress of the lower resonator film affects the working state and performance of the upper resonator to a certain degree; thus, the lower the stress on the upper and lower resonator films, the better (i.e., the films do not bend, as in FIGS. 3A-3C), so that the two resonators do not affect performance; of course, if the upper and lower resonators are not in contact due to bending in the cavity, some of the resonator performance is sacrificed by adjusting the stress (as shown in fig. 3E-3G) to ensure that the two are not in contact.
Fig. 4A is a schematic cross-sectional view of the bulk acoustic wave resonator taken along line a-a' in fig. 2, in which fig. 4A, a part of the non-electrode connecting end of the bottom electrode 202 of the upper resonator in the circumferential direction is electrically connected to the top electrode 104 of the lower resonator (shown on the right side in fig. 4A), and another part of the non-electrode connecting end of the bottom electrode 202 of the upper resonator in the circumferential direction is provided on the upper surface of the piezoelectric layer 103 of the lower resonator (shown on the left side in fig. 4A) without being electrically connected to the top electrode 104 of the lower resonator and outside the non-electrode connecting end of the top electrode 104 in the lateral direction, according to an exemplary embodiment of the present invention.
Fig. 4B is a schematic cross-sectional view of the bulk acoustic wave resonator taken along line B-B' in fig. 2 according to an exemplary embodiment of the present invention, and in fig. 4B, the electrode connection end of the bottom electrode of the upper resonator is electrically connected to the electrode connection end of the top electrode of the lower resonator, but the non-electrode connection end of the bottom electrode of the upper resonator and the non-electrode connection end of the top electrode of the lower resonator are not connected to each other.
In the above embodiments, the bottom electrode of the upper resonator and the top electrode of the lower resonator are electrically connected to each other, but the present invention is not limited thereto. In the case where two bulk acoustic wave resonators stacked one above the other share an acoustic decoupling layer, the bottom electrode of the upper resonator and the top electrode of the lower resonator may also be electrically isolated from each other.
Fig. 5A is a schematic cross-sectional view of a bulk acoustic wave resonator taken along line a-a' in fig. 2 according to an exemplary embodiment of the present invention, in fig. 5A, the bottom electrode 202 of the upper resonator and the top electrode 104 of the lower resonator are not electrically connected, and the ends of the non-electrode connection ends of the bottom electrode 202 of the upper resonator are outside the top electrode 104 of the lower resonator and are both disposed on the upper surface of the piezoelectric layer 103 of the lower resonator.
Fig. 5B is a schematic cross-sectional view of the bulk acoustic wave resonator taken along the line a-a' in fig. 2, in which the non-electrode connecting end of the bottom electrode 202 of the upper resonator and the non-electrode connecting end of the top electrode 104 of the lower resonator are not electrically connected, an end of a part of the non-electrode connecting end of the bottom electrode of the upper resonator is disposed on the upper surface of the piezoelectric layer 103 of the lower resonator (see the left side in fig. 5B) and an end of the other part is located inside the boundary of the common cavity in the lateral direction (see the right side in fig. 5B), according to an exemplary embodiment of the present invention.
Fig. 5C is a schematic cross-sectional view of the bulk acoustic wave resonator taken along the line C-C' in fig. 2, in which the non-electrode connection end of the bottom electrode 202 of the upper resonator and the non-electrode connection end of the top electrode 104 of the lower resonator are not electrically connected, and the electrode connection end of the bottom electrode 202 of the upper resonator and the electrode connection end of the top electrode 104 of the lower resonator are not electrically connected, according to an exemplary embodiment of the present invention.
Fig. 10 is a cross-sectional view of a resonator assembly in which upper and lower resonator active areas are acoustically isolated by a cavity, and upper and lower resonators are electrically isolated from each other in a left side view of fig. 10, according to an exemplary embodiment of the present invention.
In the left side view of fig. 10, the top electrode 104 is in the first electrode layer, and in the left side view of fig. 10, the aforementioned first electrode layer includes the top electrode 104 and a non-top electrode layer that is electrically isolated from the non-electrode connection end of the top electrode 104 via the breaking structure 106 to the outside of the non-electrode connection end of the top electrode 104 (i.e., a portion to the left of the breaking structure 106 in fig. 10). In fig. 10, the bottom electrode 202 is in a second electrode layer, which, as shown in the left side view of fig. 10, includes the bottom electrode 202 and a non-bottom electrode layer that is electrically isolated from the non-electrode connecting end of the bottom electrode 202 via the breaking structure 206 and is outside the non-electrode connecting end of the bottom electrode 202 (i.e., the right portion of the breaking structure 206 in fig. 10). In the left side view of fig. 10, the electrode connecting end of the bottom electrode 202 covers the non-top electrode layer, which covers the electrode connecting end of the top electrode 104.
Figures 6A-6C are cross-sectional schematic views of a bulk acoustic wave resonator assembly according to various embodiments of the present invention showing a cavity 201 between the bottom electrode of the upper resonator and the top electrode of the lower resonator and a support 401 disposed therein.
In the example shown in fig. 3E-3G, the controlling stress can reduce the probability of the upper and lower resonators contacting each other, but when the area of the resonator is larger, as shown in fig. 6A-6C, a support 401 can be added, the support 401 can contact with the top or top electrode of the lower resonator, and the height of the support is less than or equal to the height of the cavity, which means the top of the support contacts with the bottom or bottom electrode of the upper resonator, and the height of the support is less than the height of the cavity, which means the top of the support does not contact with the upper resonator, and when the local thickness of the cavity is reduced due to the bending of the resonator, the top of the support contacts with the upper resonator to play a supporting role. In the structure shown in fig. 6A-6C, the support member 401 is in contact with both the bottom electrode of the upper resonator and the top electrode of the lower resonator.
The fabrication of the structure shown in fig. 3A is illustrated with reference to fig. 7A-7E.
First, as shown in fig. 7A, a bottom electrode 102, a piezoelectric layer 103, and an electrode material layer for a top electrode 104 are formed on a substrate S, wherein the upper surface of the substrate S is also provided with a recess for forming an acoustic mirror 101, and the recess is filled with a sacrificial material. In fig. 7A-7E, passivation layers, layers of frequencies tuned to be less relevant to the concepts of the present patent are not shown.
Next, as shown in fig. 7B, a sacrificial material layer is deposited on the structure of fig. 7A, and in order to improve the growth quality of the subsequent film layer, the deposited sacrificial material layer is subjected to a surface treatment by a CMP (chemical mechanical polishing) method, and then an etching patterning process is performed on the sacrificial material layer to form a sacrificial layer 301, which is removed in the subsequent process to form a cavity 201. The sacrificial material may be polysilicon, amorphous silicon, silicon dioxide, doped silicon dioxide, or the like.
Again, an electrode metal layer for forming the bottom electrode 202 of the upper resonator is deposited in a sputtering or evaporation process or the like on the structure shown in fig. 7B. Next, etching is performed on the electrode metal layer corresponding to the bottom electrode 202 and the electrode metal layer corresponding to the top electrode 104 by photolithography and etching processes to form the structure shown in fig. 7C.
Again, as shown in fig. 7D, the sacrificial material in fig. 7C is released to form the cavity 201 and the acoustic mirror cavity 101.
Finally, the piezoelectric layer 203 and the top electrode 204 are formed on the structure shown in FIG. 7D, resulting in the structure shown in FIG. 3A, as shown in FIG. 7E.
It is noted that in the above manufacturing process, the sacrificial material may also be released after the piezoelectric layer and the top electrode of the upper resonator are formed to form the cavity 201 and the acoustic mirror cavity 101.
Fig. 8A and 8B schematically illustrate a structure of a method of fabricating the support member of fig. 6A-6C. The structure shown in fig. 6A is manufactured differently from the structure shown in fig. 3A, in that when the structure shown in fig. 6A is manufactured, before the step corresponding to fig. 7B is performed, the support member 401 is required to be manufactured on the structure shown in fig. 7A, then, in the step corresponding to fig. 7B, the sacrificial material layer is deposited to cover the support member 401, then, the deposited sacrificial material layer is subjected to surface treatment by a CMP (chemical mechanical polishing) method, and then, an etching patterning process is performed on the sacrificial material layer to form the sacrificial layer 301 shown in fig. 8A, which is used for removing to form the cavity 201 in a subsequent process.
In fig. 8A, the height of the support member 401 is smaller than the thickness of the sacrificial layer 301, so that the upper end of the support member 401 is not in contact with the bottom electrode of the upper resonator in the finally formed structure, while in fig. 8B, the height of the support member 401 is the same as the thickness of the sacrificial layer 301, so that the upper end of the support member 401 is in contact with the bottom electrode of the upper resonator in the finally formed structure.
For the structure shown in fig. 7A, the fabrication process is similar to that of the structure of fig. 3A, except that in the step corresponding to fig. 7B, the fabrication of the sacrificial layer is changed to the fabrication of the acoustic reflection layer, and in the step corresponding to fig. 7D, the step of removing the sacrificial layer 301 is eliminated.
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 base of the resonator, and with respect to one 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 (i.e., the effective area center), and one side or one end of a component close to the effective area center is the inner side or the inner end, and one side or one end of the component away from the effective area center 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, the bulk acoustic wave resonator according to the present invention may be used to form a filter or an electronic device. 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.
Based on the above, the invention provides the following technical scheme:
1. a bulk acoustic wave resonator assembly comprising:
a substrate;
at least two resonators which are bulk acoustic wave resonators and are stacked in a thickness direction of the substrate on one side of the substrate, the at least two resonators including a first resonator and a second resonator, the second resonator being above the first resonator, the first resonator having a first top electrode, a first piezoelectric layer, a first bottom electrode and a first acoustic mirror, the second resonator having a second top electrode, a second piezoelectric layer, a second bottom electrode and a second acoustic mirror,
wherein:
an acoustic decoupling layer in the form of a cavity is arranged between the first top electrode and the second bottom electrode, and the acoustic decoupling layer serves as the second acoustic mirror.
2. The assembly of claim 1, wherein:
the first top electrode and the second bottom electrode are electrically connected to each other.
3. The assembly of claim 2, wherein:
the end of the non-electrode connection terminal of the first top electrode and the end of the non-electrode connection terminal of the second bottom electrode are connected to each other.
4. The assembly of claim 3, wherein:
the end of the non-electrode connection terminal of the first top electrode and the end of the non-electrode connection terminal of the second bottom electrode meet each other in the entire circumferential direction.
5. The assembly of claim 3, wherein:
an end portion of a part of the non-electrode connecting end of the second bottom electrode in the circumferential direction is provided on the upper surface of the first piezoelectric layer and outside the non-electrode connecting end of the first bottom electrode in the horizontal direction.
6. The assembly of claim 2, wherein:
and a conductive support member is arranged between the first top electrode and the second bottom electrode, and the first top electrode and the second bottom electrode are electrically connected with each other through the conductive support member.
7. The assembly of claim 2, wherein:
the electrode connection end of the first top electrode and the electrode connection end of the second bottom electrode are electrically connected to each other.
8. The assembly of claim 2, wherein:
the electrode connecting end of the first top electrode and the electrode connecting end of the second bottom electrode are electrically connected with each other, and the non-electrode connecting end of the first top electrode and the non-electrode connecting end of the second bottom electrode are electrically connected with each other.
10. The assembly of claim 3, wherein:
the length of a connection path where the first top electrode and the second bottom electrode are electrically connected to each other at the electrode non-connection end is less than 5 μm.
11. The assembly of claim 1, wherein:
the first top electrode and the second bottom electrode are electrically isolated from each other.
12. The assembly of claim 11, wherein:
an end portion of at least a part of the non-electrode connection end of the second bottom electrode in the circumferential direction or an end portion of the electrode connection end of the second bottom electrode is provided on the upper surface of the first piezoelectric layer, and the end portion is located outside the non-electrode connection end of the first top electrode in the horizontal direction.
13. The assembly of claim 12, wherein:
an end of a part of the non-electrode connecting end of the second bottom electrode in the circumferential direction or an end of the electrode connecting end of the second bottom electrode is provided on the upper surface of the first piezoelectric layer, and an end of another part of the non-electrode connecting end of the second bottom electrode in the circumferential direction is located inside a boundary of the acoustic decoupling layer in the horizontal direction.
14. The assembly of claim 13, wherein:
the assembly comprises a first electrode layer and a second electrode layer;
the first electrode layer includes a first top electrode and a non-top electrode layer electrically isolated from the non-electrode connection end of the first top electrode to be outside the non-electrode connection end of the first top electrode;
the second electrode layer includes a second bottom electrode and a non-bottom electrode layer electrically isolated from the non-electrode connection end of the second bottom electrode and located outside the non-electrode connection end of the second bottom electrode;
the electrode connecting end of the second bottom electrode covers the non-top electrode layer, and the non-bottom electrode layer covers the electrode connecting end of the first top electrode.
15. The assembly of claim 1, wherein:
at least one of the first top electrode and the second bottom electrode has a convex shape away from the cavity; or
The portion of the first top electrode defining the lower side of the cavity and the portion of the second bottom electrode defining the upper side of the cavity each have a straight shape.
16. The assembly of claim 15, wherein:
the assembly is provided with a support between the first top electrode and the second bottom electrode.
17. The assembly of claim 2, wherein:
the resonant frequency of the lower resonator is more than 0.5GHz, and the thickness of the first top electrode is less than
Figure BDA0002621667080000142
And/or
The resonant frequency of the upper resonator is more than 0.5GHz, and the thickness of the second bottom electrode is less than
Figure BDA0002621667080000143
18. The assembly of claim 17, wherein:
the resonant frequency of the lower resonator is more than 3GHz, and the thickness of the first top electrode is less than
Figure BDA0002621667080000144
And/or
The resonant frequency of the upper resonator is more than 3GHz, and the thickness of the second bottom electrode is less than
Figure BDA0002621667080000141
19. A bulk acoustic wave resonator assembly comprising:
at least two resonators which are adjacently stacked from bottom to top in the thickness direction of the assembly are bulk acoustic wave resonators, the at least two resonators comprise a first resonator and a second resonator, an acoustic decoupling layer in a cavity mode is arranged between a top electrode of the first resonator and a bottom electrode of the second resonator, and the acoustic decoupling layer serves as an acoustic mirror of the second resonator.
20. The assembly of claim 1 or 19, wherein:
the at least two resonators include a first resonator, a second resonator, and a third resonator stacked in a thickness direction;
the first acoustic decoupling layer is arranged between the top electrode of the first resonator and the bottom electrode of the second resonator, the second acoustic decoupling layer in the form of a cavity is arranged between the top electrode of the second resonator and the bottom electrode of the third resonator, and the second acoustic decoupling layer forms an acoustic mirror of the third resonator.
21. The assembly of claim 20, wherein:
the boundary of the second acoustic decoupling layer is outside the boundary of the first acoustic decoupling layer in the horizontal direction.
22. A method of manufacturing a bulk acoustic wave resonator assembly, comprising:
step 1: forming a first structure for a first bulk acoustic wave resonator on a surface of a substrate, the first bulk acoustic wave resonator comprising a first acoustic mirror, a first bottom electrode, a first piezoelectric layer, a first top electrode;
step 2: arranging a patterned sacrificial material layer on the first structure formed in the step 1;
and step 3: forming a second structure for a second bulk acoustic wave resonator on the structure of step 2, the second bulk acoustic wave resonator including a second acoustic mirror, a second bottom electrode, a second piezoelectric layer, and a second top electrode, the sacrificial material layer being located between the first top electrode and the second bottom electrode in a thickness direction of the substrate;
and 4, step 4: releasing the sacrificial material layer to form a cavity constituting a second acoustic mirror of a second bulk acoustic wave resonator.
23. The method of claim 22, wherein:
in step 2, further comprising providing a support in the layer of sacrificial material.
24. A filter comprising a bulk acoustic wave resonator assembly according to any one of claims 1-21.
25. An electronic device comprising the filter of 24 or the bulk acoustic wave resonator assembly of any one of claims 1-21.
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 (24)

1. A bulk acoustic wave resonator assembly comprising:
a substrate;
at least two resonators which are bulk acoustic wave resonators and are stacked in a thickness direction of the substrate on one side of the substrate, the at least two resonators including a first resonator and a second resonator, the second resonator being above the first resonator, the first resonator having a first top electrode, a first piezoelectric layer, a first bottom electrode and a first acoustic mirror, the second resonator having a second top electrode, a second piezoelectric layer, a second bottom electrode and a second acoustic mirror,
wherein:
an acoustic decoupling layer in the form of a cavity is arranged between the first top electrode and the second bottom electrode, and the acoustic decoupling layer serves as the second acoustic mirror.
2. The assembly of claim 1, wherein:
the first top electrode and the second bottom electrode are electrically connected to each other.
3. The assembly of claim 2, wherein:
the end of the non-electrode connection terminal of the first top electrode and the end of the non-electrode connection terminal of the second bottom electrode are connected to each other.
4. The assembly of claim 3, wherein:
the end of the non-electrode connection terminal of the first top electrode and the end of the non-electrode connection terminal of the second bottom electrode meet each other in the entire circumferential direction.
5. The assembly of claim 3, wherein:
an end portion of a part of the non-electrode connecting end of the second bottom electrode in the circumferential direction is provided on the upper surface of the first piezoelectric layer and outside the non-electrode connecting end of the first bottom electrode in the horizontal direction.
6. The assembly of claim 2, wherein:
and a conductive support member is arranged between the first top electrode and the second bottom electrode, and the first top electrode and the second bottom electrode are electrically connected with each other through the conductive support member.
7. The assembly of claim 2, wherein:
the electrode connection end of the first top electrode and the electrode connection end of the second bottom electrode are electrically connected to each other.
8. The assembly of claim 2, wherein:
the electrode connecting end of the first top electrode and the electrode connecting end of the second bottom electrode are electrically connected with each other, and the non-electrode connecting end of the first top electrode and the non-electrode connecting end of the second bottom electrode are electrically connected with each other.
9. The assembly of claim 3, wherein:
the length of a connection path where the first top electrode and the second bottom electrode are electrically connected to each other at the electrode non-connection end is less than 5 μm.
10. The assembly of claim 1, wherein:
the first top electrode and the second bottom electrode are electrically isolated from each other.
11. The assembly of claim 10, wherein:
an end portion of at least a part of the non-electrode connection end of the second bottom electrode in the circumferential direction or an end portion of the electrode connection end of the second bottom electrode is provided on the upper surface of the first piezoelectric layer, and the end portion is located outside the non-electrode connection end of the first top electrode in the horizontal direction.
12. The assembly of claim 11, wherein:
an end of a part of the non-electrode connecting end of the second bottom electrode in the circumferential direction or an end of the electrode connecting end of the second bottom electrode is provided on the upper surface of the first piezoelectric layer, and an end of another part of the non-electrode connecting end of the second bottom electrode in the circumferential direction is located inside a boundary of the acoustic decoupling layer in the horizontal direction.
13. The assembly of claim 12, wherein:
the assembly comprises a first electrode layer and a second electrode layer;
the first electrode layer includes a first top electrode and a non-top electrode layer electrically isolated from the non-electrode connection end of the first top electrode to be outside the non-electrode connection end of the first top electrode;
the second electrode layer includes a second bottom electrode and a non-bottom electrode layer electrically isolated from the non-electrode connection end of the second bottom electrode and located outside the non-electrode connection end of the second bottom electrode;
the electrode connecting end of the second bottom electrode covers the non-top electrode layer, and the non-bottom electrode layer covers the electrode connecting end of the first top electrode.
14. The assembly of claim 1, wherein:
at least one of the first top electrode and the second bottom electrode has a convex shape away from the cavity; or
The portion of the first top electrode defining the lower side of the cavity and the portion of the second bottom electrode defining the upper side of the cavity each have a straight shape.
15. The assembly of claim 14, wherein:
the assembly is provided with a support between the first top electrode and the second bottom electrode.
16. The assembly of claim 2, wherein:
the resonant frequency of the lower resonator is more than 0.5GHz, and the thickness of the first top electrode is less than
Figure RE-FDA0002864969340000031
And/or
The resonant frequency of the upper resonator is more than 0.5GHz, and the thickness of the second bottom electrode is less than
Figure RE-FDA0002864969340000032
17. The assembly of claim 16, wherein:
the resonant frequency of the lower resonator is more than 3GHz, and the thickness of the first top electrode is less than
Figure RE-FDA0002864969340000033
And/or
The resonant frequency of the upper resonator is more than 3GHz, and the thickness of the second bottom electrode is less than
Figure RE-FDA0002864969340000034
18. A bulk acoustic wave resonator assembly comprising:
at least two resonators which are adjacently stacked from bottom to top in the thickness direction of the assembly are bulk acoustic wave resonators, the at least two resonators comprise a first resonator and a second resonator, an acoustic decoupling layer in a cavity mode is arranged between a top electrode of the first resonator and a bottom electrode of the second resonator, and the acoustic decoupling layer serves as an acoustic mirror of the second resonator.
19. The assembly of claim 1 or 18, wherein:
the at least two resonators include a first resonator, a second resonator, and a third resonator stacked in a thickness direction;
the first acoustic decoupling layer is arranged between the top electrode of the first resonator and the bottom electrode of the second resonator, the second acoustic decoupling layer in the form of a cavity is arranged between the top electrode of the second resonator and the bottom electrode of the third resonator, and the second acoustic decoupling layer forms an acoustic mirror of the third resonator.
20. The assembly of claim 19, wherein:
the boundary of the second acoustic decoupling layer is outside the boundary of the first acoustic decoupling layer in the horizontal direction.
21. A method of manufacturing a bulk acoustic wave resonator assembly, comprising:
step 1: forming a first structure for a first bulk acoustic wave resonator on a surface of a substrate, the first bulk acoustic wave resonator comprising a first acoustic mirror, a first bottom electrode, a first piezoelectric layer, a first top electrode;
step 2: arranging a patterned sacrificial material layer on the first structure formed in the step 1;
and step 3: forming a second structure for a second bulk acoustic wave resonator on the structure of step 2, the second bulk acoustic wave resonator including a second acoustic mirror, a second bottom electrode, a second piezoelectric layer, and a second top electrode, the sacrificial material layer being located between the first top electrode and the second bottom electrode in a thickness direction of the substrate;
and 4, step 4: releasing the sacrificial material layer to form a cavity constituting a second acoustic mirror of a second bulk acoustic wave resonator.
22. The method of claim 21, wherein:
in step 2, further comprising providing a support in the layer of sacrificial material.
23. A filter comprising the bulk acoustic wave resonator assembly of any one of claims 1-20.
24. An electronic device comprising the filter of claim 23 or the bulk acoustic wave resonator assembly of any one of claims 1-20.
CN202010785120.2A 2020-08-06 2020-08-06 Bulk acoustic wave resonator assembly with acoustic decoupling layer, manufacturing method of bulk acoustic wave resonator assembly, filter and electronic device Pending CN114070224A (en)

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