CN117176101A

CN117176101A - Bulk acoustic wave resonator, preparation method thereof, filter and electronic equipment

Info

Publication number: CN117176101A
Application number: CN202211328696.1A
Authority: CN
Inventors: 万晨庚
Original assignee: Beijing Xinxi Semiconductor Technology Co ltd
Current assignee: Beijing Xinxi Semiconductor Technology Co ltd
Priority date: 2022-10-27
Filing date: 2022-10-27
Publication date: 2023-12-05

Abstract

The embodiment of the disclosure provides a bulk acoustic wave resonator, a preparation method thereof, a filter and electronic equipment. The bulk acoustic wave resonator includes: a substrate (10), an acoustic mirror (19) being formed on one side of the substrate (10), wherein the acoustic mirror (19) comprises a first step and a second step; an electrode ring (11) formed on a first step of the acoustic mirror (19) and surrounding the acoustic mirror (19), wherein an upper surface of the electrode ring (11) is flush with an upper surface of the acoustic mirror (19); a bottom electrode (12) formed above the acoustic mirror (19) and covering the acoustic mirror (19) and the electrode ring (11), wherein a face of the bottom electrode (12) facing the electrode ring (11) and the acoustic mirror (19) is horizontal, and a seed layer is formed below the bottom electrode (12); a piezoelectric functional layer (13); and a top electrode (16).

Description

Bulk acoustic wave resonator, preparation method thereof, filter and electronic equipment

Technical Field

The present invention relates to the field of electronic communications technologies, and in particular, to a bulk acoustic wave resonator, a method for manufacturing the bulk acoustic wave resonator, a filter, and an electronic device.

Background

The film bulk acoustic resonator filter (filmbulk acoustic resonator, FBAR) is receiving increasing attention as one of the core devices of Radio Frequency (RF) front-end, mainly because of the high power, high bandwidth and excellent roll-off performance of the FBAR filter, and can well meet the current demands for Radio Frequency performance. In particular, the FABR filter has great advantages in terms of high power compared to the SAW (surface acoustic wave ) filter because the FBAR belongs to a longitudinal wave propagation mode of a bulk acoustic wave and more heat dissipation channels.

However, the bottom electrode structure of the current FBAR is disposed above the acoustic mirror and the supporting structure, and vibration mainly occurs in the effective area of the Fang Xiezhen device on the acoustic mirror during the operation of the FBAR, and vibration outside the effective area is greatly reduced, so that the bottom electrode may generate a certain stress concentration at the interface with the acoustic mirror, so that the bottom electrode becomes a dead weak point, and is easy to break. Particularly at high power, the vibration amplitude of the resonator increases, where it is more likely to break, resulting in no further increase in FBAR power.

Further, heat dissipation of the FBAR is mainly performed by the bottom electrode, but as described above, only a portion of the bottom electrode is in contact with the substrate silicon, so that heat generated by the piezoelectric layer cannot be effectively dissipated, and a heat dissipation channel needs to be increased to increase the power capacity.

In addition, when the frequency is high, the thicknesses of the electrodes of each layer of the FBAR are small, so that the resistance between the resonators of the filter is large, and the resistance value (Rs) of the series resonance point of the large resonator has a certain influence on the passband of the filter.

Accordingly, a resonator, a filter, and an electronic device having good structural performance, heat dissipation performance, and bandpass performance are desired.

Disclosure of Invention

In view of the above, embodiments of the present disclosure provide a bulk acoustic wave resonator and a method for manufacturing the same, which at least partially solve the problems in the prior art.

In a first aspect, embodiments of the present disclosure provide a bulk acoustic wave resonator, including:

a substrate (10), an acoustic mirror (19) being formed on one side of the substrate (10), wherein the acoustic mirror (19) comprises a first step and a second step;

an electrode ring (11) formed on a first step of the acoustic mirror (19) and surrounding the acoustic mirror (19), wherein an upper surface of the electrode ring (11) is flush with an upper surface of the acoustic mirror (19);

a bottom electrode (12) formed above the acoustic mirror (19) and covering the acoustic mirror (19) and the electrode ring (11), wherein a face of the bottom electrode (12) facing the electrode ring (11) and the acoustic mirror (19) is horizontal, and a seed layer is formed below the bottom electrode (12);

A piezoelectric functional layer (13) which is formed on the surface of the bottom electrode (12) away from the acoustic mirror (19) and the electrode ring (11) and covers the bottom electrode (12); and

and a top electrode (16) formed on a surface of the piezoelectric functional layer (13) away from the bottom electrode (12).

According to a specific implementation of the embodiment of the disclosure, the bulk acoustic wave resonator further includes a support layer (23) formed over the substrate (10), wherein a lower surface of the support layer (23) is flush with an upper surface of the substrate (10), and the acoustic mirror (19) is formed on one side of the support layer (23) by etching one side of the support layer (23).

According to a specific implementation of an embodiment of the present disclosure, the acoustic mirror (19) is formed on one side of the substrate (10) by etching one side of the substrate (10).

According to a specific implementation of the embodiment of the disclosure, the bulk acoustic wave resonator further includes a buried electrode (22) formed on the second step of the acoustic mirror (19) and located at the bottom of the acoustic mirror (19).

According to a specific implementation of the embodiment of the disclosure, the etching angle of the side wall of the second step of the acoustic mirror (19) is 85 ° to 95 °, and the buried electrode (22) is not connected to the electrode ring (11).

According to a specific implementation manner of the embodiment of the disclosure, the etching angle of the side wall of the second step of the acoustic mirror (19) is 90 degrees, and the embedded electrode (22) is not connected with the electrode ring (11).

According to a specific implementation manner of the embodiment of the disclosure, an etching angle of a side wall of the second step of the acoustic mirror (19) is smaller than 85 degrees, and the embedded electrode (22) is connected with the electrode ring (11).

According to a specific implementation manner of the embodiment of the disclosure, an etching angle of a side wall of the second step of the acoustic mirror (19) is 20-80 degrees, and the embedded electrode (22) is connected with the electrode ring (11).

According to a specific implementation manner of the embodiment of the disclosure, the bulk acoustic wave resonator further comprises an air ring structure (14) and a frame structure, which are formed on a part between the piezoelectric functional layer (13) and the top electrode (16), wherein the air ring structure (14) and the frame structure are matched on a non-connecting side to form a frame wing structure (15), a frame bridge structure (21) is formed on the connecting side, one side, close to the center of the bulk acoustic wave resonator, of the air ring structure (14) is surrounded by the frame wing structure (15), and both left and right sides of the connecting side of the air ring structure (14) are surrounded by the frame bridge structure (21).

According to one specific implementation of an embodiment of the present disclosure, the top electrode (16) includes an upwardly convex structure (18).

According to a specific implementation of an embodiment of the disclosure, the bulk acoustic wave resonator further includes a protective layer (17) formed on a face of the top electrode (16) remote from the piezoelectric functional layer (13).

According to a specific implementation of an embodiment of the present disclosure, the outer boundary of the lateral width of the electrode ring (11) does not exceed the outer boundary of the bottom electrode (12), and the longitudinal thickness of the electrode ring (11) does not exceed the longitudinal depth of the acoustic mirror (19).

In a second aspect, embodiments of the present disclosure provide a method of manufacturing a bulk acoustic wave resonator, comprising:

forming an acoustic mirror (19) on one side of a substrate (10), wherein forming the acoustic mirror (19) comprises forming a first step and a second step of the acoustic mirror (19);

forming an electrode ring (11) surrounding the acoustic mirror (19) on a first step of the acoustic mirror (19), wherein an upper surface of the electrode ring (11) is flush with an upper surface of the acoustic mirror (19);

forming a bottom electrode (12) covering the acoustic mirror (19) and the electrode ring (11) above the acoustic mirror (19), wherein a face of the bottom electrode (12) facing the electrode ring (11) and the acoustic mirror (19) is set horizontal, and forming a seed layer below the bottom electrode (12);

Forming a piezoelectric functional layer (13) covering the bottom electrode (12) on a face of the bottom electrode (12) remote from the acoustic mirror (19) and the electrode ring (11); and

a top electrode (16) is formed on the surface of the piezoelectric functional layer (13) remote from the bottom electrode (12).

According to a specific implementation of an embodiment of the disclosure, the method further includes: -forming a support layer (23) over the substrate (10), and-forming the acoustic mirror (19) on one side of the support layer (23) by etching one side of the support layer (23), wherein a lower surface of the support layer (23) is flush with an upper surface of the substrate (10).

According to a specific implementation of an embodiment of the disclosure, the method further includes: the acoustic mirror (19) is formed on one side of the substrate (10) by etching the one side of the substrate (10).

According to a specific implementation of an embodiment of the disclosure, the method further includes: a buried electrode (22) is formed on the second step of the acoustic mirror (19).

According to a specific implementation of an embodiment of the disclosure, the etching angle of the side wall of the second step of the acoustic mirror (19) is 85 ° to 95 °, and the buried electrode (22) is not connected to the electrode ring (11).

According to a specific implementation of the embodiment of the disclosure, the etching angle of the side wall of the second step of the acoustic mirror (19) is 90 degrees, and the embedded electrode (22) is not connected with the electrode ring (11).

According to a specific implementation of the embodiment of the disclosure, the etching angle of the side wall of the second step of the acoustic mirror (19) is less than 85 degrees, and the embedded electrode (22) is connected with the electrode ring (11).

According to a specific implementation manner of the embodiment of the disclosure, an etching angle of a side wall of a portion of the acoustic mirror (19) corresponding to the embedded electrode (22) is 20-80 degrees, and the embedded electrode (22) is connected with the electrode ring (11).

According to a specific implementation of an embodiment of the disclosure, the method further includes: an air ring structure (14) and a frame structure are formed on a part between the piezoelectric functional layer (13) and the top electrode (16), wherein the air ring structure (14) and the frame structure are matched on a non-connecting side to form a frame wing structure (15), a frame bridge structure (21) is formed on the connecting side, one side, close to the center of the bulk acoustic wave resonator, of the air ring structure (14) is surrounded by the frame wing structure (15), and the left side and the right side of the connecting side of the air ring structure (14) are surrounded by the frame bridge structure (21).

The method further comprises the steps of: an upwardly protruding structure (18) associated with the top electrode (16) is formed.

According to a specific implementation of an embodiment of the disclosure, the method further includes: a protective layer (17) is formed on the surface of the top electrode (16) facing away from the piezoelectric functional layer (13).

In a third aspect, embodiments of the present disclosure provide a filter comprising a bulk acoustic wave resonator according to the first aspect of embodiments of the present disclosure or any specific implementation thereof.

In a fourth aspect, embodiments of the present disclosure provide an electronic device comprising a bulk acoustic wave resonator according to the first aspect of the embodiments of the present disclosure or any specific implementation thereof, or comprising a filter according to the third aspect of the embodiments of the present disclosure.

According to the bulk acoustic resonator, the filter and the electronic equipment, structural reinforcement of the bottom electrode at the junction with the acoustic mirror is realized by changing structural arrangement of the bottom electrode, the substrate and the acoustic mirror, so that stress concentration is reduced, and the reliability of vibration under high power is improved. In addition, by adding the structure extending into the substrate, a heat transfer channel is added, so that the power capacity of the resonator can be further improved. Further, the buried electrode can reduce the resistance of the bottom electrode and further increase the heat transfer channel. Meanwhile, the structure can play a role in electromagnetic shielding, an electromagnetic shielding layer is not required to be prepared at the bottom in the later integrated preparation process of the device, an excellent electromagnetic shielding effect of a resonator level can be brought inside the filter, and the cost of the device is reduced.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present disclosure, and other drawings may be obtained according to these drawings without inventive effort to a person of ordinary skill in the art.

FIG. 1 is a block diagram of a first embodiment of a bulk acoustic wave resonator provided by the present disclosure;

FIG. 2 is a block diagram of a second embodiment of a bulk acoustic wave resonator provided by the present disclosure;

FIG. 3 is a block diagram of a third embodiment of a bulk acoustic wave resonator provided by the present disclosure;

FIG. 4 is a block diagram of a fourth embodiment of a bulk acoustic wave resonator provided by the present disclosure;

fig. 5 is a block diagram of a fifth embodiment of a bulk acoustic wave resonator provided by the present disclosure;

fig. 6 is a block diagram of a sixth embodiment of a bulk acoustic wave resonator provided by the present disclosure;

fig. 7 is a block diagram of a seventh embodiment of a bulk acoustic wave resonator provided by the present disclosure;

fig. 8 is a schematic diagram of a method of making a bulk acoustic wave resonator according to a first embodiment of the present disclosure;

fig. 9 is a schematic diagram of a method of making a bulk acoustic wave resonator according to a first embodiment of the present disclosure;

Fig. 10 is a schematic diagram of a method of making a bulk acoustic wave resonator according to a first embodiment of the present disclosure;

fig. 11 is a schematic diagram of a method of making a bulk acoustic wave resonator according to a first embodiment of the present disclosure;

fig. 12 is a schematic diagram of a method of making a bulk acoustic wave resonator according to a first embodiment of the present disclosure;

fig. 13 is a schematic diagram of a method of making a bulk acoustic wave resonator according to a first embodiment of the present disclosure;

fig. 14 is a schematic diagram of a method of making a bulk acoustic wave resonator according to a first embodiment of the present disclosure;

fig. 15 is a schematic diagram of a method of making a bulk acoustic wave resonator according to a first embodiment of the present disclosure;

fig. 16 is a schematic diagram of a method of making a bulk acoustic wave resonator according to a first embodiment of the present disclosure.

Detailed Description

Embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

Other advantages and effects of the present disclosure will become readily apparent to those skilled in the art from the following disclosure, which describes embodiments of the present disclosure by way of specific examples. It will be apparent that the described embodiments are merely some, but not all embodiments of the present disclosure. The disclosure may be embodied or practiced in other different specific embodiments, and details within the subject specification may be modified or changed from various points of view and applications without departing from the spirit of the disclosure. It should be noted that the following embodiments and features in the embodiments may be combined with each other without conflict. All other embodiments, which can be made by one of ordinary skill in the art without inventive effort, based on the embodiments in this disclosure are intended to be within the scope of this disclosure.

It is noted that various aspects of the embodiments are described below within the scope of the following claims. It should be apparent that the aspects described herein may be embodied in a wide variety of forms and that any specific structure and/or function described herein is merely illustrative. Based on the present disclosure, one skilled in the art will appreciate that one aspect described herein may be implemented independently of any other aspect, and that two or more of these aspects may be combined in various ways. For example, an apparatus may be implemented and/or a method practiced using any number of the aspects set forth herein. In addition, such apparatus may be implemented and/or such methods practiced using other structure and/or functionality in addition to one or more of the aspects set forth herein.

It should also be noted that the illustrations provided in the following embodiments merely illustrate the basic concepts of the disclosure by way of illustration, and only the components related to the disclosure are shown in the drawings and are not drawn according to the number, shape and size of the components in actual implementation, and the form, number and proportion of the components in actual implementation may be arbitrarily changed, and the layout of the components may be more complicated.

In addition, in the following description, specific details are provided in order to provide a thorough understanding of the examples. However, it will be understood by those skilled in the art that the aspects may be practiced without these specific details.

Next, the structure of the bulk acoustic wave resonator of the embodiment of the present disclosure will be specifically described with reference to the drawings.

First, reference numerals in the embodiments of the present disclosure are described.

10: the substrate is made of monocrystalline silicon, gallium arsenide, sapphire, quartz, silicon carbide, SOI, etc.

11: the electrode ring is made of molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or a composite or alloy of the above metals.

12: the bottom electrode is made of molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or a composite or alloy of the above metals.

13: the piezoelectric functional layer is made of monocrystalline piezoelectric material, polycrystalline piezoelectric material or rare earth element doped material with a certain atomic ratio.

Specifically, the single crystal piezoelectric material is selected from single crystal aluminum nitride, single crystal gallium nitride, single crystal lithium niobate, single crystal lead zirconate titanate (PZT), single crystal potassium niobate, single crystal quartz thin film, or single crystal lithium tantalate; polycrystalline piezoelectric material (corresponding to single crystal, non-single crystal material), optionally polycrystalline aluminum nitride, zinc oxide, PZT, etc.; the rare earth element doped material containing the above-mentioned material in a certain atomic ratio may be, for example, doped aluminum nitride 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), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), or the like.

14: the air ring structure is a ring structure formed by air or other low acoustic resistance dielectric material (e.g., siO) above the piezoelectric function layer 13 of the resonator. Specifically, in the embodiment of the present disclosure, at the non-connection side, the structure formed by the piezoelectric functional layer 13 and the frame structure or the top electrode is a cantilever structure; at the connecting side, the structure formed by the piezoelectric functional layer 13 and the frame structure or the top electrode is a bridge structure.

15: and a half-bridge structure formed by the frame wing structure and the non-connecting edge of the resonator right above the air ring structure. The material can be molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or a composite of the above metals or an alloy thereof, etc.

16: the top electrode may be made of the same material as the bottom electrode 12, and may be made of molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, or a composite of the above metals, or an alloy thereof. It should be understood that the top electrode 16 and bottom electrode 12 materials may also be different.

17: the material of the protective layer is not limited, and is preferably selected from aluminum nitride, silicon oxide, and the like, for trimming and protecting the top electrode 16.

18: the material of the upward protruding structure can be 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, so that the parasitic mode of the resonator can be limited, and the performance is improved.

19: an acoustic mirror, abbreviated as acoustic mirror, a reflecting structure composed of air. The lower surface of the acoustic mirror 19, which is a resonator, and the piezoelectric layers and electrodes constituting the resonator have large acoustic impedance differences, and can reflect sound waves inside the resonator, confine the sound wave energy in the acoustic mirror, and form resonance. It should be understood that Bragg reflection layers and other equivalent forms may also be employed. Further, the acoustic mirror may be formed on the upper surface side of the substrate, or may be formed on the support layer side above the substrate, and is composed of the substrate, the support layer, and the bottom electrode. In the embodiments of the present disclosure, a cavity is used to form an acoustic mirror structure on the upper surface side of the substrate or on the support layer side above the substrate.

20: the sacrificial material may be silicon oxide and its dopants.

21: frame bridge structure: the resonator connecting side forms a bridge structure directly above the air ring structure.

22: the embedded electrode is made of molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or a composite of the above metals or an alloy thereof.

23: the support layer is made of silicon nitride, silicon oxide, polysilicon and its adulterants, and organic matters.

First embodiment

Next, with reference to fig. 1, a structure of a first embodiment of a bulk acoustic wave resonator provided by the present disclosure is described. It should be understood that fig. 1 shows a cross-sectional view of a bulk acoustic wave resonator.

As shown in fig. 1, the structure of the first embodiment of the bulk acoustic wave resonator provided in the present disclosure includes a substrate 10, an electrode ring 11, a bottom electrode 12, a piezoelectric functional layer 13, an air ring structure 14, a frame wing structure 15, a top electrode 16, a protective layer 17, an upward protruding structure 18, an acoustic mirror 19, a frame bridge structure 21, and a buried electrode 22.

The substrate 10 may be a single layer of any one of single crystal silicon, gallium arsenide, sapphire, quartz, silicon carbide, SOI, and the like.

On one side of the substrate 10, i.e. the upper side as shown in the figure, an acoustic mirror 19 is etched, the acoustic mirror 19 being capable of reflecting acoustic waves inside the resonator, confining the acoustic wave energy in the resonator, forming a resonance. Specifically, the lower surface of the acoustic mirror 19, which is a resonator, and the piezoelectric layers and electrodes constituting the resonator have large acoustic impedance differences, and can reflect sound waves inside the resonator, confine the sound wave energy in the resonator, and form resonance. Further, as shown in fig. 1, the acoustic mirror 19 has a first step and a second step, and the first step and the second step have different etching angles.

It should be noted that the "first step" and the "second step" are intended to explain the sidewall structure of the acoustic mirror 19 formed by etching. As shown in fig. 8 below, 19-1 indicates a step at an upper position of the acoustic mirror 19, i.e., a first step, and 19-2 indicates a step at a lower position of the acoustic mirror 19, i.e., a second step. Specifically, the first step is located at an upper portion of the acoustic mirror 19 (or referred to as the periphery of the acoustic mirror 19), and the second step is located at a lower portion of the acoustic mirror 19 (or referred to as the bottom of the acoustic mirror 19).

An electrode ring 11 surrounding the acoustic mirror 19 is deposited on a first step (i.e., periphery) of the acoustic mirror 19, and an upper surface of the electrode ring 11 is flush with the acoustic mirror 19 and an upper surface of the substrate 11. The electrode ring 11 and the substrate 10 overlap in the thickness direction, and can be regarded as that the electrode ring portion of the bottom electrode 12 is embedded into the substrate 10, which is equivalent to structural reinforcement of the bottom electrode 12 at the interface with the acoustic mirror 19, so that stress concentration can be reduced, and the reliability of vibration of the resonator under high power can be improved. In addition, the electrode ring 11 also increases the path for heat transfer, thereby further increasing the power capacity of the resonator.

Note that after the electrode ring 11 is deposited on the first step of the acoustic mirror 19, only the second step structure remains in the acoustic mirror 19.

The material of the electrode ring 11 may be selected from molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, or a composite of the above metals, an alloy thereof, or the like.

In addition, the maximum value of the lateral width of the electrode ring 11 is flush with the outer boundary of the lateral width of the bottom electrode 12, i.e., does not exceed the outer boundary of the bottom electrode 12; whereas in the thickness direction the maximum longitudinal thickness of the electrode ring 11 does not exceed the longitudinal depth of the acoustic mirror 19.

A buried electrode 22 is deposited on the second step of the acoustic mirror 19. The buried electrode 22 is in contact with the electrode ring 11. The buried electrode 22 may be prepared in the same layer as the electrode ring 11 and have the same thickness as the electrode ring 11. It is noted, however, that the embedded electrode 22 may also be made not in the same layer as the electrode ring 11 and have a different thickness than the electrode ring 11. The buried electrode 22 can reduce the resistance of the bottom electrode of the resonator, improve the resistance Rs of the series resonance point of the resonator and further increase the heat transfer channel. In addition, the embedded electrode 22 also plays a role of electromagnetic shielding, so that excellent electromagnetic shielding effect of resonator level can be brought into the filter without preparing an electromagnetic shielding layer at the bottom in the later device integration preparation process, and the manufacturing cost is reduced.

The material of the embedded electrode 22 may be selected from molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, a composite of these metals, an alloy thereof, or the like. Meanwhile, the material of the embedded electrode 22 may be optionally the same as or different from that of the electrode ring 11.

Further, in the present embodiment, the electrode ring 11 and the buried electrode 22 are prepared to be matched with the etching angle of the side wall of the acoustic mirror. Specifically, in the present embodiment, in order to reduce the area of the resonator, the etching angle of the side wall of the first step of the acoustic mirror 19 is as perpendicular as possible, for example, 80 ° to 100 °, preferably 90 °. In addition, the etching angle of the side wall of the second step of the acoustic mirror 19 is smaller than 85 ° and preferably 20 ° to 80 ° unlike the conventional 90 ° etching angle, thereby allowing the electrode ring structure and the buried electrode to be connected and thus achieving a reduction in the resistance value of the bottom electrode.

A bottom electrode 12 covering the acoustic mirror 19 and the electrode ring 11 is deposited above the acoustic mirror 19. The lower surface of the bottom electrode 12, i.e. the surface facing the electrode ring 11 and the acoustic mirror 19, is horizontal. Furthermore, although not shown in the drawings, a seed layer may be deposited above the acoustic mirror 19 and below the bottom electrode 12.

A piezoelectric functional layer 13 is deposited over the bottom electrode 12, i.e. on the face of the bottom electrode 12 remote from the acoustic mirror 19 and the electrode ring 11. The piezoelectric functional layer 13 may be a single crystal piezoelectric material, a polycrystalline piezoelectric material, or a rare earth element doped material containing the above materials in a certain atomic ratio.

An air ring structure 14 is provided on the piezoelectric functional layer 13. As described above, in the embodiment of the present disclosure, it is a ring-shaped structure formed of air or other low acoustic resistance dielectric material (e.g., siO) above the piezoelectric functional layer 13 of the resonator. Further, as shown in fig. 1, in the embodiment of the present disclosure, a frame structure is also provided. More specifically, the frame structure and the air ring structure 14 are fitted at the non-connecting sides to form the frame wing structure 15, and at the connecting sides to form the frame bridge structure 21. That is, in the present embodiment, the structure arrangement of the non-connection side and the connection side is different, both the left and right sides of the connection side of the air ring structure 14 are surrounded by the frame bridge structure 21, and only one side of the non-connection side of the air ring structure 14 is surrounded, in the present embodiment, the side of the non-connection side of the air ring structure 14 near the center of the bulk acoustic wave resonator is surrounded by the frame wing structure 15. In other words, the air ring structure 14 is partly surrounded by the frame wing structure 15 and is entirely surrounded by the frame bridge structure 21.

In the presently disclosed embodiments, the term "connecting side" refers to the side of the resonator that is connected to the other resonator or test electrode, typically by the top electrode 16 or bottom electrode 12, so that the top or bottom electrode of this side is not etched (as shown on the right side of FIG. 1, its top electrode 16 is not etched); the term "non-connecting side" means that the top electrode 16 or bottom electrode 12 of the resonator on this side is etched away without being connected to other resonators or pads (as shown on the left side of fig. 1, with its top electrode 16 etched). That is, in fig. 1, the left side is a non-connecting side, and the right side is a connecting side.

Further, as shown in fig. 1, on the frame wing structure 15, the frame bridge structure 21, and the piezoelectric functional layer 13, there are provided a top electrode 16 and an upward protruding structure 18, the top electrode 16 may be made of the same material as or different from the bottom electrode 12, and the upward protruding structure 18 is a protruding structure on the top electrode 16, and molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, or a composite of the above metals, or an alloy thereof, or the like is selected.

In addition, in order to protect the top electrode 16 and the protruding structure 18 thereof, a protective layer 17 is further provided on the top electrode 16 and the protruding structure 18, and the structure of the protective layer 17 is not limited.

In other words, in the first embodiment of the present disclosure, a bulk acoustic wave resonator includes:

a substrate 10, wherein an acoustic mirror 19 is etched on one side of the substrate 10, and the acoustic mirror 19 comprises a first step and a second step, the etching angle of the side wall of the first step is 80 ° to 100 °, preferably 90 °, and the etching angle of the side wall of the second step is less than 85 °, preferably 20 ° to 80 °;

an electrode ring 11 formed on the first step of the acoustic mirror 19 and surrounding the acoustic mirror 19, wherein an upper surface of the electrode ring 11 is flush with an upper surface of the acoustic mirror 19;

a buried electrode 22 formed on the second step of the acoustic mirror 19 at the bottom of the acoustic mirror 19, wherein the buried electrode 22 is in contact with the electrode ring 11;

a bottom electrode 12 formed above the acoustic mirror 19 and covering the acoustic mirror 19 and the electrode ring 11, wherein a face of the bottom electrode 12 facing the electrode ring 11 and the acoustic mirror 19 is horizontal, an outer boundary of a lateral width of the electrode ring 11 does not exceed an outer boundary of the bottom electrode 12, and a longitudinal thickness of the electrode ring 11 does not exceed a longitudinal depth of the acoustic mirror 19;

a piezoelectric functional layer 13 formed on a face of the bottom electrode 12 away from the acoustic mirror 19 and the electrode ring 11, and covering the bottom electrode 12;

A top electrode 16 formed on a face of the piezoelectric functional layer 13 remote from the bottom electrode 12, the top electrode 16 including an upwardly convex structure 18; and

a protective layer 17 formed on a surface of the top electrode 16 remote from the piezoelectric functional layer 13,

wherein the bulk acoustic wave resonator further comprises an air ring structure 14 and a frame structure formed on a portion between the piezoelectric functional layer 13 and the top electrode 16, the air ring structure 14 and the frame structure are matched on the non-connecting side to form a frame wing structure 15, a frame bridge structure 21 is formed on the connecting side, one side, close to the center of the bulk acoustic wave resonator, of the air ring structure 14 is surrounded by the frame wing structure 15, and the left side and the right side of the connecting side of the air ring structure 14 are surrounded by the frame bridge structure 21.

According to the bulk acoustic wave resonator of the first embodiment of the disclosure, structural reinforcement of the bottom electrode at the junction with the acoustic mirror is realized by changing structural arrangement of the bottom electrode, the substrate and the acoustic mirror, so that stress concentration is reduced, and reliability of vibration under high power is improved. In addition, by adding the electrode ring 11 and the embedded electrode 22 which extend into the substrate, a heat transfer channel is increased, so that the power capacity of the resonator can be further improved. Furthermore, the embedded electrode 22 can play a role of electromagnetic shielding, and the device can bring excellent electromagnetic shielding effect of the resonator level inside the filter without preparing an electromagnetic shielding layer at the bottom in the later integrated preparation process, so that the cost of the device is reduced.

Second embodiment

Next, a second embodiment of the present disclosure will be described with reference to fig. 2. As shown in fig. 2, in order to reduce the chip size (die size) and to reduce the process complexity of the product, compared with the first embodiment shown in fig. 1, in the second embodiment, the etching angle of the side wall of the second step of the acoustic mirror 19 is nearly vertical, for example, 85 ° to 95 °, preferably 90 °. At this time, the buried electrode 22 is not in contact with the electrode ring 11.

In other words, in the second embodiment of the present disclosure, a bulk acoustic wave resonator includes:

a substrate 10, wherein an acoustic mirror 19 is etched on one side of the substrate 10, and the acoustic mirror 19 comprises a first step and a second step, the etching angle of the side wall of the first step is 80 ° to 100 °, preferably 90 °, and the etching angle of the side wall of the second step is 85 ° to 95 °, preferably 90 °;

a buried electrode 22 formed on the second step of the acoustic mirror 19 at the bottom of the acoustic mirror 19, wherein the buried electrode 22 is not in contact with the electrode ring 11;

It is to be noted that, in order to avoid obscuring the present invention, only the differences of the second embodiment from the first embodiment will be described herein, and the description of the remaining identical structures will be omitted.

Third embodiment

Next, a third embodiment of the present disclosure will be described with reference to fig. 3. As shown in fig. 3, the buried electrode 22 may not be deposited on the second step of the acoustic mirror 19.

In other words, in the third embodiment of the present disclosure, a bulk acoustic wave resonator includes:

Although the buried electrode 22 is not provided in the third embodiment, the electrode ring 11 has enabled structural reinforcement of the bottom electrode at the interface with the acoustic mirror, thereby reducing stress concentration and improving reliability of vibration at high power. At the same time, by adding electrode rings 11 extending into the substrate, the heat transfer channels can also be increased, thereby further increasing the power capacity of the resonator.

Further, it is to be noted that although the third embodiment is shown with the etching angle of the side wall of the second step being 85 ° to 95 °, preferably 90 °, it is to be understood that the etching angle of the side wall of the second step is less than 85 °, preferably 20 ° to 80 °, also applies to the embodiment omitting the buried electrode 22.

In addition, in order to avoid obscuring the present invention, only the differences between the third embodiment and the second embodiment will be described herein, and the description of the remaining identical structures will be omitted.

Fourth embodiment

Next, a fourth embodiment of the present disclosure will be described with reference to fig. 4. As shown in fig. 4, the air ring structure 14, the frame wing structure 15, and the frame bridge structure 21 between the piezoelectric functional layer 13 and the top electrode 16, and the protective layer 17 over the top electrode 16 may also be omitted as compared to the first embodiment. Furthermore, as shown in fig. 4, etching of the top electrode 16 is not required to obtain the raised structure 18.

In other words, in the fourth embodiment of the present disclosure, a bulk acoustic wave resonator includes:

a piezoelectric functional layer 13 formed on a face of the bottom electrode 12 away from the acoustic mirror 19 and the electrode ring 11, and covering the bottom electrode 12; and

a top electrode 16 formed on a face of the piezoelectric functional layer 13 remote from the bottom electrode 12, the top electrode 16 including an upwardly convex structure 18.

Although the air ring structure 14, the frame wing structure 15 and the frame bridge structure 21 between the piezoelectric functional layer 13 and the top electrode 16, and the protective layer 17 above the top electrode 16, and the protruding structure 18 are omitted in the fourth embodiment, the electrode ring 11 and the buried electrode 22 have realized structural reinforcement of the bottom electrode at the interface with the acoustic mirror, thereby reducing stress concentration and improving the reliability of vibration at high power. In addition, by adding the electrode ring 11 and the embedded electrode 22 which extend into the substrate, a heat transfer channel is also added, so that the power capacity of the resonator can be further improved. Furthermore, the embedded electrode 22 can play a role of electromagnetic shielding, and the device can bring excellent electromagnetic shielding effect of the resonator level inside the filter without preparing an electromagnetic shielding layer at the bottom in the later integrated preparation process, so that the cost of the device is reduced.

Further, it is to be noted that, in order to avoid obscuring the present invention, only the differences of the fourth embodiment from the first embodiment will be described herein, and the description of the remaining identical structures will be omitted.

Fifth embodiment

Next, a fifth embodiment of the present disclosure will be described with reference to fig. 5. As shown in fig. 5, in the second embodiment, the etching angle of the side wall of the second step of the acoustic mirror 19 is nearly vertical, for example, 85 ° to 95 °, preferably 90 °, in order to reduce the chip size (die size) and to reduce the process complexity of the product, as compared with the fourth embodiment. At this time, the buried electrode 22 is not in contact with the electrode ring 11.

In other words, in the fifth embodiment of the present disclosure, a bulk acoustic wave resonator includes:

Also, although the air ring structure 14, the frame wing structure 15, and the frame bridge structure 21 between the piezoelectric functional layer 13 and the top electrode 16, the protective layer 17 over the top electrode 16, and the raised structure 18 are omitted in the fifth embodiment, and the embedded electrode 22 is not in contact with the electrode ring 11, the electrode ring 11 and the embedded electrode 22 have realized structural reinforcement of the bottom electrode at the interface with the acoustic mirror, thereby reducing stress concentration and improving reliability of vibration at high power. In addition, by adding the electrode ring 11 and the embedded electrode 22 which extend into the substrate, a heat transfer channel is also added, so that the power capacity of the resonator can be further improved. Furthermore, the embedded electrode 22 can play a role of electromagnetic shielding, and the device can bring excellent electromagnetic shielding effect of the resonator level inside the filter without preparing an electromagnetic shielding layer at the bottom in the later integrated preparation process, so that the cost of the device is reduced. .

Further, it is to be noted that, in order to avoid obscuring the present invention, only the differences of the second embodiment from the first embodiment will be described herein, and the description of the remaining identical structures will be omitted.

Sixth embodiment

Next, a sixth embodiment of the present disclosure will be described with reference to fig. 6. As shown in fig. 6, compared with the fifth embodiment, in the sixth embodiment, the buried electrode 22 is omitted.

In other words, in the sixth embodiment of the present disclosure, a bulk acoustic wave resonator includes:

Although the air ring structure 14, the frame wing structure 15, and the frame bridge structure 21 between the piezoelectric functional layer 13 and the top electrode 16, the protective layer 17 over the top electrode 16, the raised structure 18, and the buried electrode 22 are omitted in the sixth embodiment, the electrode ring 11 has realized structural reinforcement of the bottom electrode at the interface with the acoustic mirror, thereby reducing stress concentration and improving the reliability of vibration under high power. In addition, the power capacity of the resonator can be further improved by increasing the channels for heat transfer through the increased electrode ring 11 protruding into the substrate.

Further, it is to be noted that although the sixth embodiment is shown with the etching angle of the side wall of the second step being 85 ° to 95 °, preferably 90 °, it is to be understood that the etching angle of the side wall of the second step is less than 85 °, preferably 20 ° to 80 °, also applies to the embodiment omitting the buried electrode 22.

In addition, in order to avoid obscuring the present invention, only the differences between the sixth embodiment and the fifth embodiment will be described herein, and the description of the remaining identical structures will be omitted.

Seventh embodiment

Next, a seventh embodiment of the present disclosure will be described with reference to fig. 7. As shown in fig. 7, in comparison with the sixth embodiment, in the seventh embodiment, the mirror 19 is not formed by etching one side of the substrate 10, but the support layer 23 is deposited over the substrate 10 first, and then the mirror 19 is formed by etching one side of the support layer 23.

a substrate 10, a supporting layer 23 is deposited above the substrate 10, and an acoustic mirror 19 is etched on one side of the supporting layer 23, wherein the acoustic mirror 19 comprises a first step and a second step, the etching angle of the side wall of the first step is 80 ° to 100 °, preferably 90 °, and the etching angle of the side wall of the second step is 85 ° to 95 °, preferably 90 °;

Further, it is to be noted that although the seventh embodiment is shown by adding the support layer 23 on the basis of the sixth embodiment, it is to be understood that the seventh embodiment may be shown by adding the support layer 23 on the basis of any one of the above-described first to fifth embodiments. In order to avoid unnecessarily obscuring the present invention, a detailed description of the deformable embodiments is omitted herein.

Method embodiments of preparing a bulk acoustic wave resonator according to embodiments of the present disclosure

Next, a process of manufacturing a bulk acoustic wave resonator according to a first embodiment of the present invention will be described in detail with reference to fig. 8 to 16.

Step 1. As shown in FIG. 8, the structure of the acoustic mirror 19 is etched on the substrate 10, and the Etching process may be dry Etching or wet Etching, and the dry Etching may be sputtering and ion beam milling, plasma Etching (Plasma Etching), high-pressure Plasma Etching, high-density Plasma (HDP) Etching, or Reactive Ion Etching (RIE). As described above with respect to the first embodiment, the acoustic mirror 19 includes the two-layer structure of the first step and the second step. In fig. 8, 19-1 indicates a first step, and 19-2 indicates a second step. The first step is used to deposit the electrode ring 11 and the second step is used to deposit the buried electrode 22 (although it is noted that in some embodiments, the second step is empty and no buried electrode 22 is present).

In particular, the etching angle of the side wall of the first step is as vertical as possible, for example, 80 ° to 100 °, preferably 90 °; the etching angle of the side wall of the second step is less than 85 °, preferably 20 ° to 80 °.

Step 2. As shown in fig. 9, a metal material is deposited on the etched substrate 10 to form an electrode ring 11 and a buried bottom electrode 22. Specifically, the electrode ring 11 surrounding the acoustic mirror 19 is deposited on a first step of the acoustic mirror 19, and the buried electrode 22 is deposited on a second step of the acoustic mirror 19. Thereafter, a layer of phosphosilicate glass PSG is deposited as a sacrificial material 20 over the electrode ring 11 and the buried electrode 22, the sacrificial material 20 having a thickness greater than the depth of the structure of the acoustic mirror 19 (the reference to the acoustic mirror 19 is omitted from FIGS. 9-15 for unnecessary blurring). The deposition may be, for example, chemical vapor deposition CVD.

Step 3 As shown in FIG. 10, the structure shown in FIG. 9 is subjected to Chemical Mechanical Polishing (CMP) to expose the upper surface of the substrate 10 covered by the sacrificial material, and to make the upper surface of the sacrificial material layer flush with the upper surface of the substrate 10, and the upper surface of the electrode ring 11 flush with the upper surface of the acoustic mirror 19, at which time the acoustic mirror 19 is filled with the sacrificial material 20.

Step 4. As shown in FIG. 11, a seed layer (not shown) and bottom electrode 12 material are deposited and etched over the structure shown in FIG. 10 to obtain a bottom electrode 12 structure. Specifically, a metal layer may be deposited on the surfaces of the substrate 10 and the sacrificial material by a sputtering or evaporation process or the like, and the metal layer may be patterned by photolithography and etching processes to form the bottom electrode 12.

Step 5. As shown in fig. 12, a piezoelectric functional layer 13 is deposited on the structure shown in fig. 11.

Step 6, as shown in fig. 13, an air ring structure sacrificial layer is deposited on the piezoelectric functional layer 13, and the frame wing structure 15 and the frame bridge structure 21 are patterned and prepared. Thereafter, the air ring structure sacrificial layer is released, resulting in the air ring structure 14.

Step 7. As shown in fig. 14, a metal layer is deposited on the upper surface of the structure shown in fig. 13 and patterned into a top electrode 16 and a raised structure 18.

Step 8. As shown in fig. 15, a passivation layer material is disposed and patterned on the upper surface of the structure shown in fig. 14 to form a protective layer 17.

And 9, as shown in fig. 16, releasing the materials of the sacrificial layer 20 and the air ring structure sacrificial layer to obtain the final bulk acoustic wave resonator.

As described above with reference to fig. 8 to 16, a method of manufacturing a bulk acoustic wave resonator according to a first embodiment of the present disclosure is described. Although not described in detail, it is noted that the respective structural features, materials, and the like of the bulk acoustic wave resonator described above with reference to fig. 1 are also applicable to the manufacturing method.

Although the process of manufacturing the bulk acoustic wave resonator according to the first embodiment of the present disclosure is described above by way of illustration, it should be understood that the bulk acoustic wave resonators of the second, third, fourth, fifth, sixth and seventh embodiments may be similarly manufactured.

For example, the method of manufacturing the bulk acoustic wave resonator in the second embodiment is similar to that in the first embodiment, except that in step 1, the etching angle of the side wall of the second step of the acoustic mirror 19 is 85 ° to 95 °, preferably 90 °.

For example, the method of manufacturing the bulk acoustic wave resonator in the third embodiment is similar to that in the second embodiment, except that in step 2, only the electrode ring 11 is deposited and the buried electrode 22 is not deposited. Of course, as in the third embodiment, the etching angle of the side wall of the second step may also be less than 85 °, preferably 20 ° to 80 °.

For example, the method of manufacturing the bulk acoustic wave resonator in the fourth embodiment is similar to that in the first embodiment, except that steps 6 and 8 are omitted, and in step 7, only the top electrode 16 is deposited and patterned, and the bump structure 18 is not formed.

For example, the method of manufacturing the bulk acoustic wave resonator in the fifth embodiment is similar to that in the fourth embodiment, except that in step 1, the etching angle of the side wall of the second step of the acoustic mirror 19 is 85 ° to 95 °, preferably 90 °.

For example, the method of manufacturing the bulk acoustic wave resonator in the sixth embodiment is similar to that in the fifth embodiment, except that in step 2, only the electrode ring 11 is deposited and the buried electrode 22 is not deposited. Of course, as described in the sixth embodiment, the etching angle of the side wall of the second step may also be less than 85 °, preferably 20 ° to 80 °.

For example, the method of manufacturing the bulk acoustic wave resonator in the seventh embodiment is similar to that in the sixth embodiment, except that in step 1, the support layer 23 is deposited over the substrate 10, and then one side of the support layer 23 is etched to obtain the structure of the acoustic mirror 19. Further, as also described in the seventh embodiment, the steps of the method for depositing the support layer 23 over the substrate 10 and then etching one side of the support layer 23 to obtain the structure of the acoustic mirror 19 may also be added to the method for manufacturing the bulk acoustic wave resonator of any one of the first to fifth embodiments described above.

It is to be noted that, in order to avoid unnecessarily obscuring the present application, a detailed description of the method of producing the bulk acoustic wave resonator in the second to seventh embodiments is omitted herein. The method of preparation thereof is clear by reference to the context of the present application.

Furthermore, bulk acoustic wave resonators according to the present disclosure may be used to form filters or electronic devices, as will be appreciated by those skilled in the art. The electronic device includes, but is not limited to, intermediate products such as a radio frequency front end, a filtering and amplifying module, and terminal products such as a mobile phone, a WIFI, an unmanned aerial vehicle, and the like.

Further, the present disclosure may also have the following configuration:

(1) A bulk acoustic wave resonator, comprising:

(2) The bulk acoustic resonator according to (1), characterized in that it further comprises a support layer (23) formed over the substrate (10), wherein a lower surface of the support layer (23) is flush with an upper surface of the substrate (10), and the acoustic mirror (19) is formed on one side of the support layer (23) by etching one side of the support layer (23).

(3) The bulk acoustic resonator according to (1), characterized in that the acoustic mirror (19) is formed on one side of the substrate (10) by etching one side of the substrate (10).

(4) The bulk acoustic wave resonator according to (1), characterized in that it further comprises a buried electrode (22) formed on the second step of the acoustic mirror (19) at the bottom of the acoustic mirror (19).

(5) The bulk acoustic resonator according to (4), characterized in that the etching angle of the side wall of the second step of the acoustic mirror (19) is 85 ° to 95 °, and the buried electrode (22) is not connected to the electrode ring (11).

(6) The bulk acoustic resonator according to (5), characterized in that the etching angle of the side wall of the second step of the acoustic mirror (19) is 90 °, and the buried electrode (22) is not connected to the electrode ring (11).

(7) The bulk acoustic resonator according to (4), characterized in that the etching angle of the side wall of the second step of the acoustic mirror (19) is less than 85 °, and the buried electrode (22) is connected to the electrode ring (11).

(8) The bulk acoustic resonator according to (7), characterized in that the etching angle of the side wall of the second step of the acoustic mirror (19) is 20 ° to 80 °, and the buried electrode (22) is connected to the electrode ring (11).

(9) The bulk acoustic wave resonator according to (1) or (2) or (3), characterized in that the bulk acoustic wave resonator further comprises an air ring structure (14) and a frame structure formed on a part between the piezoelectric functional layer (13) and the top electrode (16), wherein the air ring structure (14) and the frame structure are fitted on the non-connecting side to form a frame wing structure (15), a frame bridge structure (21) is formed on the connecting side, one side of the non-connecting side of the air ring structure (14) close to the center of the bulk acoustic wave resonator is surrounded by the frame wing structure (15), and both the left and right sides of the connecting side of the air ring structure (14) are surrounded by the frame bridge structure (21).

(10) The bulk acoustic resonator according to (1) or (2) or (3), characterized in that the top electrode (16) comprises an upwardly convex structure (18).

(11) Bulk acoustic resonator according to claim (1), characterized in that the outer boundary of the lateral width of the electrode ring (11) does not exceed the outer boundary of the bottom electrode (12), the longitudinal thickness of the electrode ring (11) does not exceed the longitudinal depth of the acoustic mirror (19).

(12) A method of making a bulk acoustic wave resonator comprising:

(13) The method of manufacturing a bulk acoustic wave resonator according to (12), characterized in that the method further comprises: -forming a support layer (23) over the substrate (10), and-forming the acoustic mirror (19) on one side of the support layer (23) by etching one side of the support layer (23), wherein a lower surface of the support layer (23) is flush with an upper surface of the substrate (10).

(14) The method of manufacturing a bulk acoustic wave resonator according to (12), characterized in that the method further comprises: the acoustic mirror (19) is formed on one side of the substrate (10) by etching the one side of the substrate (10).

(15) The method of manufacturing a bulk acoustic wave resonator according to (12), characterized in that the method further comprises: a buried electrode (22) is formed on the second step of the acoustic mirror (19).

(16) A method of manufacturing a bulk acoustic wave resonator according to (15), characterized in that the etching angle of the side wall of the second step of the acoustic mirror (19) is 85 ° to 95 °, the buried electrode (22) being disconnected from the electrode ring (11).

(17) A method of manufacturing a bulk acoustic wave resonator according to (16), characterized in that the etching angle to the side wall of the second step of the acoustic mirror (19) is 90 °, the buried electrode (22) being disconnected from the electrode ring (11).

(18) A method of manufacturing a bulk acoustic wave resonator according to (15), characterized in that the etching angle of the side wall of the second step of the acoustic mirror (19) is less than 85 °, and the buried electrode (22) is connected to the electrode ring (11).

(19) Method for producing a bulk acoustic resonator according to (18), characterized in that the etching angle of the side wall of the portion of the acoustic mirror (19) corresponding to the buried electrode (22) is 20 ° to 80 °, the buried electrode (22) being connected to the electrode ring (11).

(20) The method for producing a bulk acoustic wave resonator according to (12), (13) or (14), characterized in that the method further comprises: an air ring structure (14) and a frame structure are formed on a part between the piezoelectric functional layer (13) and the top electrode (16), wherein the air ring structure (14) and the frame structure are matched on a non-connecting side to form a frame wing structure (15), a frame bridge structure (21) is formed on the connecting side, one side, close to the center of the bulk acoustic wave resonator, of the air ring structure (14) is surrounded by the frame wing structure (15), and the left side and the right side of the connecting side of the air ring structure (14) are surrounded by the frame bridge structure (21).

(21) The method for producing a bulk acoustic wave resonator according to claim (12), (13) or (14), characterized in that the method further comprises: an upwardly protruding structure (18) associated with the top electrode (16) is formed.

(22) A filter comprising the bulk acoustic wave resonator according to any one of (1) to (11).

(23) An electronic device comprising the bulk acoustic wave resonator according to any one of (1) to (11) or comprising the filter according to (22).

The foregoing is merely specific embodiments of the disclosure, but the protection scope of the disclosure is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the disclosure are intended to be covered by the protection scope of the disclosure. Therefore, the protection scope of the present disclosure shall be subject to the protection scope of the claims.

Claims

1. A bulk acoustic wave resonator, comprising:

2. The bulk acoustic resonator according to claim 1, characterized in that it further comprises a support layer (23) formed over the substrate (10), wherein a lower surface of the support layer (23) is flush with an upper surface of the substrate (10), the acoustic mirror (19) being formed on one side of the support layer (23) by etching one side of the support layer (23).

3. Bulk acoustic resonator according to claim 1, characterized in that the acoustic mirror (19) is formed on one side of the substrate (10) by etching one side of the substrate (10).

4. The bulk acoustic wave resonator according to claim 1, characterized in that it further comprises a buried electrode (22) formed on the second step of the acoustic mirror (19) at the bottom of the acoustic mirror (19).

5. The bulk acoustic resonator according to claim 4, characterized in that the etching angle of the side wall of the second step of the acoustic mirror (19) is 85 ° to 95 °, the buried electrode (22) being unconnected to the electrode ring (11).

6. Bulk acoustic resonator according to claim 5, characterized in that the etching angle of the side wall of the second step of the acoustic mirror (19) is 90 °, the buried electrode (22) being disconnected from the electrode ring (11).

7. Bulk acoustic resonator according to claim 4, characterized in that the etching angle of the side wall of the second step of the acoustic mirror (19) is less than 85 °, the buried electrode (22) being connected to the electrode ring (11).

8. Bulk acoustic resonator according to claim 7, characterized in that the etching angle of the side wall of the second step of the acoustic mirror (19) is 20 ° to 80 °, the buried electrode (22) being connected to the electrode ring (11).

9. A bulk acoustic wave resonator according to claim 1 or 2 or 3, characterized in that the bulk acoustic wave resonator further comprises an air ring structure (14) and a frame structure formed on a part between the piezoelectric functional layer (13) and the top electrode (16), wherein the air ring structure (14) and the frame structure cooperate to form a frame wing structure (15) at the non-connecting side, a frame bridge structure (21) is formed at the connecting side, a side of the non-connecting side of the air ring structure (14) near the center of the bulk acoustic wave resonator is surrounded by the frame wing structure (15), and both the left and right sides of the connecting side of the air ring structure (14) are surrounded by the frame bridge structure (21).

10. A bulk acoustic wave resonator according to claim 1 or 2 or 3, characterized in that the top electrode (16) comprises an upwardly convex structure (18).

11. Bulk acoustic resonator according to claim 1, characterized in that the outer boundary of the lateral width of the electrode ring (11) does not exceed the outer boundary of the bottom electrode (12), the longitudinal thickness of the electrode ring (11) not exceeding the longitudinal depth of the acoustic mirror (19).

12. A method of making a bulk acoustic wave resonator comprising:

13. The method of making a bulk acoustic wave resonator according to claim 12, characterized in that the method further comprises: -forming a support layer (23) over the substrate (10), and-forming the acoustic mirror (19) on one side of the support layer (23) by etching one side of the support layer (23), wherein a lower surface of the support layer (23) is flush with an upper surface of the substrate (10).

14. The method of making a bulk acoustic wave resonator according to claim 12, characterized in that the method further comprises: the acoustic mirror (19) is formed on one side of the substrate (10) by etching the one side of the substrate (10).

15. The method of making a bulk acoustic wave resonator according to claim 12, characterized in that the method further comprises: a buried electrode (22) is formed on the second step of the acoustic mirror (19).

16. A method of manufacturing a bulk acoustic resonator according to claim 15, characterized in that the etching angle of the side wall of the second step of the acoustic mirror (19) is 85 ° to 95 °, the buried electrode (22) being disconnected from the electrode ring (11).

17. A method of manufacturing a bulk acoustic resonator according to claim 16, characterized in that the etching angle to the side wall of the second step of the acoustic mirror (19) is 90 °, the buried electrode (22) being disconnected from the electrode ring (11).

18. A method of manufacturing a bulk acoustic resonator according to claim 15, characterized in that the etching angle of the side wall of the second step of the acoustic mirror (19) is less than 85 °, the buried electrode (22) being connected to the electrode ring (11).

19. A method of manufacturing a bulk acoustic resonator according to claim 18, characterized in that the etching angle of the side wall of the portion of the acoustic mirror (19) corresponding to the buried electrode (22) is 20 ° to 80 °, the buried electrode (22) being connected to the electrode ring (11).

20. A method of making a bulk acoustic wave resonator according to claim 12 or 13 or 14, characterized in that the method further comprises: an air ring structure (14) and a frame structure are formed on a part between the piezoelectric functional layer (13) and the top electrode (16), wherein the air ring structure (14) and the frame structure are matched on a non-connecting side to form a frame wing structure (15), a frame bridge structure (21) is formed on the connecting side, one side, close to the center of the bulk acoustic wave resonator, of the air ring structure (14) is surrounded by the frame wing structure (15), and the left side and the right side of the connecting side of the air ring structure (14) are surrounded by the frame bridge structure (21).

21. A method of making a bulk acoustic wave resonator according to claim 12 or 13 or 14, characterized in that the method further comprises: an upwardly protruding structure (18) associated with the top electrode (16) is formed.

22. A filter comprising a bulk acoustic wave resonator according to any of claims 1-11.

23. An electronic device comprising a bulk acoustic wave resonator according to any of claims 1-11 or comprising a filter according to claim 22.