WO2020199509A1

WO2020199509A1 - Bulk acoustic wave resonator and manufacturing method therefor, filter and radio-frequency communication system

Info

Publication number: WO2020199509A1
Application number: PCT/CN2019/105093
Authority: WO
Inventors: 罗海龙
Original assignee: 中芯集成电路（宁波）有限公司上海分公司
Priority date: 2019-04-04
Filing date: 2019-09-10
Publication date: 2020-10-08
Also published as: CN111786654A; JP7194475B2; CN111786654B; JP2022507306A

Abstract

A bulk acoustic wave resonator and a manufacturing method therefor, a filter and a radio-frequency communication system. A bottom electrode protrusion portion (1041) and a top electrode recess portion (1081), which are formed on the periphery of a piezoelectric resonance layer (1051) and are suspended above a cavity (102) can stop the transmission of a transverse wave generated by the piezoelectric resonance layer (1051) towards the periphery of the cavity (102) and reflect the transverse wave back to an effective working region (102A), and acoustic wave loss is then reduced, such that the quality factor of the resonator is improved and the device performance can finally be improved. Furthermore, an overlapping portion between a bottom electrode lap portion (1040) and the cavity (102) and an overlapping portion between a top electrode lap portion (1080) and the cavity are both suspended, and the bottom electrode lap portion (1040) and the top electrode lap portion (1080) are staggered from each other, such that parasitic parameters can be greatly reduced, the problems of electric leakage, short circuit, etc., can be avoided, and the reliability of the device can be improved.

Description

Bulk acoustic wave resonator, its manufacturing method, filter, and radio frequency communication system

Technical field

The invention relates to the technical field of radio frequency communication, in particular to a bulk acoustic wave resonator, a manufacturing method thereof, a filter, and a radio frequency communication system.

Background technique

Radio frequency (RF) communications, such as those used in mobile phones, require radio frequency filters. Each radio frequency filter can pass the required frequency and limit all other frequencies. With the development of mobile communication technology, the amount of mobile data transmission has also risen rapidly. Therefore, under the premise that frequency resources are limited and as few mobile communication devices as possible should be used, increasing the transmission power of wireless power transmitting devices such as wireless base stations, micro base stations, or repeaters has become a problem that must be considered, and it also means that The power requirements of filters in the front-end circuits of mobile communication equipment are also increasing.

At present, high-power filters in equipment such as wireless base stations are mainly cavity filters, whose power can reach hundreds of watts, but the size of such filters is too large. Some equipment uses dielectric filters, the average power of which can reach more than 5 watts, and the size of this filter is also very large. Due to the large size, these two filters cannot be integrated into the RF front-end chip.

As MEMS technology becomes more and more mature, a filter composed of a bulk acoustic wave (BAW) resonator can well overcome the shortcomings of the above two types of filters. The bulk acoustic wave resonator has the incomparable volume advantages of ceramic dielectric filters, the incomparable operating frequency and power capacity advantages of surface acoustic wave (SAW) resonators, and has become the development trend of today's wireless communication systems.

The main part of the bulk acoustic wave resonator is a "sandwich" structure composed of bottom electrode-piezoelectric film-top electrode. The inverse piezoelectric effect of the piezoelectric film is used to convert electrical energy into mechanical energy, and the bulk acoustic wave resonator is formed in the form of sound waves. A standing wave is formed in the filter. Since the speed of acoustic waves is 5 orders of magnitude smaller than that of electromagnetic waves, the size of the filter composed of bulk acoustic wave resonators is smaller than that of traditional dielectric filters.

One of the cavity-type bulk acoustic wave resonators, its working principle is to use sound waves to reflect on the interface between the bottom electrode or the support layer and the air to confine the sound waves to the piezoelectric layer to achieve resonance. It has high Q value and low insertion The advantages such as loss and integration are widely adopted.

However, the quality factor (Q) of the currently manufactured cavity-type bulk acoustic resonator cannot be further improved, and therefore cannot meet the requirements of high-performance radio frequency systems.

Summary of the invention

The purpose of the present invention is to provide a bulk acoustic wave resonator, a manufacturing method thereof, a filter, and a radio frequency communication system, which can improve the quality factor and thereby improve the performance of the device.

In order to achieve the above objective, the present invention provides a bulk acoustic wave resonator including:

Substrate

The bottom electrode layer is disposed on the substrate, and a cavity is formed between the bottom electrode layer and the substrate, the bottom electrode layer has a bottom electrode protrusion, and the bottom electrode protrusion is located The area of the cavity is convex in a direction away from the bottom surface of the cavity;

A piezoelectric resonance layer formed on the bottom electrode layer above the cavity;

A top electrode layer formed on the piezoelectric resonance layer, the top electrode layer having a top electrode recessed portion, the top electrode recessed portion is located in a region of the cavity and toward a direction close to the bottom surface of the cavity The top electrode concave portion and the bottom electrode convex portion are both located in the cavity area on the periphery of the piezoelectric resonance layer, and the bottom electrode convex portion and the top electrode concave portion both surround the pressure The electric resonance layer extends in the peripheral direction, and the two are at least partially opposite to each other.

The present invention also provides a filter including at least one bulk acoustic wave resonator according to the present invention.

The present invention also provides a radio frequency communication system including at least one filter according to the present invention.

The present invention also provides a method for manufacturing a bulk acoustic wave resonator, including:

Providing a substrate, forming a first sacrificial layer with sacrificial protrusions on part of the substrate;

Forming a bottom electrode layer on the first sacrificial layer, and a portion of the bottom electrode layer covering the surface of the sacrificial protrusion forms a bottom electrode protrusion;

Forming a piezoelectric resonance layer on the bottom electrode layer, the piezoelectric resonance layer exposing the bottom electrode protrusions;

Forming a second sacrificial layer with a first groove in the exposed area around the piezoelectric resonance layer;

Forming a top electrode layer on the piezoelectric resonant layer and a part of the second sacrificial layer around the piezoelectric resonant layer, the portion of the top electrode layer covering the first groove forms a top electrode recess;

The second sacrificial layer and the first sacrificial layer with sacrificial protrusions are removed, the positions of the second sacrificial layer and the first sacrificial layer with sacrificial protrusions form a cavity, and the top electrode recess And the bottom electrode protruding portion are both located in a cavity area on the periphery of the piezoelectric resonance layer, and the bottom electrode protruding portion and the top electrode recessed portion both extend around the peripheral direction of the piezoelectric resonance layer, And the two are at least partially opposite.

Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

1. When electric energy is applied to the bottom electrode and the top electrode, the piezoelectric phenomenon generated in the piezoelectric resonance layer generates desired longitudinal waves propagating in the thickness direction and undesired transverse waves propagating along the plane of the piezoelectric resonance layer. The transverse wave will be blocked at the protrusions of the bottom electrode and the depressions of the top electrode on the cavity on the periphery of the piezoelectric resonance layer, and will be reflected back to the area corresponding to the piezoelectric resonance layer, thereby reducing and reducing the propagation of transverse waves. The loss caused when it enters the film layer on the periphery of the cavity, thereby improving the acoustic wave loss, so that the quality factor of the resonator is improved, and finally the device performance can be improved.

2. The periphery of the piezoelectric resonant layer is separated from the periphery of the cavity, that is, the piezoelectric resonant layer does not continuously extend above the substrate on the periphery of the cavity, which can completely limit the effective working area of the bulk acoustic wave resonator to the cavity area In addition, the bottom electrode overlap portion and the top electrode overlap portion will only extend to part of the edge of the cavity (that is, neither the bottom electrode layer nor the top electrode layer will fully cover the cavity), thereby reducing the cavity The surrounding film layer affects the longitudinal vibration generated by the piezoelectric resonant layer and improves performance.

3. Even if the bottom electrode protrusions and the top electrode recesses have overlapping parts, the overlapped parts are still in a gap structure, which can greatly reduce parasitic parameters and avoid the top electrode layer and the bottom electrode layer in the cavity area The electrical contact and other issues can improve device reliability.

4. The overlapping parts of the bottom electrode overlap portion and the top electrode overlap portion and the cavity are all suspended, and the bottom electrode overlap portion and the top electrode overlap portion are staggered in the cavity area (that is, the two are in the cavity. The cavity area does not overlap), thereby greatly reducing parasitic parameters, and avoiding leakage and short circuit problems caused by contact between the bottom electrode overlap portion and the top electrode overlap portion, and the reliability of the device can be improved.

5. The bottom electrode overlap part completely covers the cavity above the cavity part where it is located, so that a large area of the bottom electrode overlap part can be used to provide strong mechanical support for the film layer above it. Therefore, the problem of device failure due to cavity collapse is avoided.

6. The recessed part of the top electrode surrounds the resonant part of the top electrode, and the convex part of the bottom electrode surrounds the resonant part of the bottom electrode, which can block transverse waves from the periphery of the piezoelectric resonant layer in all directions, thereby obtaining better quality factors.

7. The bottom electrode protruding part, the bottom electrode resonance part and the bottom electrode overlap part are formed by the same film layer, and the film thickness is uniform, and the top electrode recessed part, the top electrode resonance part and the top electrode overlap part are formed by the same film layer. And the film thickness is uniform, which can simplify the process and reduce the cost, and because the film thickness of the bottom electrode protrusion is basically the same as the other parts of the bottom electrode layer, the film thickness of the top electrode depression is basically the same as the other parts of the top electrode layer Therefore, there will be no breakage of the convex portion of the bottom electrode and breakage of the concave portion of the top electrode, which can improve the reliability of the device.

Description of the drawings

FIG. 1A is a schematic top view of a bulk acoustic wave resonator according to an embodiment of the invention.

Figures 1B and 1C are schematic cross-sectional structural views taken along the lines XX' and YY' in Figure 1.

2A to 2D are schematic top views of the structure of the bulk acoustic wave resonator according to other embodiments of the present invention.

2E and 2F are schematic diagrams of the cross-sectional structure of the bulk acoustic wave resonator according to other embodiments of the present invention.

Fig. 3 is a flowchart of a method of manufacturing a bulk acoustic wave resonator according to an embodiment of the present invention.

4A to 4H are schematic cross-sectional views taken along XX' in FIG. 1A in a method of manufacturing a bulk acoustic wave resonator according to an embodiment of the present invention.

5 is a schematic cross-sectional view along XX' in FIG. 1A in a method for manufacturing a bulk acoustic wave resonator according to another embodiment of the present invention.

Among them, the reference signs are as follows:

100-substrate; 101-etch protection layer; 102-cavity; 102'-second groove; 102A-effective working area; 102B-invalid area; 103-first sacrificial layer; 1033'-sacrificial bump; 104 -Bottom electrode layer (that is, the remaining bottom electrode material layer); 1040-Bottom electrode overlap portion; 1041-Bottom electrode protrusion; 1042-Bottom electrode resonance portion; 1043-Bottom electrode periphery; 105-Piezoelectric material layer 1050-piezoelectric peripheral part; 1051-piezoelectric resonance layer (or called piezoelectric resonance part); 106-second sacrificial layer; 107-sacrificial protrusion; 108-top electrode layer (ie, the remaining top electrode material layer ); 1080-top electrode overlap portion; 1081-top electrode recessed portion; 1082-top electrode resonance portion; 1083-top electrode peripheral portion.

detailed description

The technical solution of the present invention will be further described in detail below with reference to the drawings and specific embodiments. According to the following description, the advantages and features of the present invention will be clearer. It should be noted that the drawings are in a very simplified form and all use imprecise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. Similarly, if the method described herein includes a series of steps, and the order of these steps presented herein is not necessarily the only order in which these steps can be performed, and some of the described steps may be omitted and/or some not described herein The other steps can be added to the method. In addition, the meaning of "staggered" between something and something in this article means that the two do not overlap in the cavity area, that is, the projections of the two on the bottom surface of the cavity do not overlap.

Please refer to FIGS. 1A to 1C. FIG. 1A is a schematic diagram of a top view of a bulk acoustic wave resonator according to an embodiment of the present invention. FIG. 1B is a schematic diagram of a cross-sectional structure along XX′ in FIG. 1 and FIG. 1C is a schematic diagram along YY in FIG. 1A. A schematic diagram of the cross-sectional structure of the line, the bulk acoustic wave resonator of this embodiment includes: a substrate, a bottom electrode layer 104, a piezoelectric resonance layer 1051, and a top electrode layer 108.

Wherein, the substrate includes a base 100 and an etching protection layer 101 covering the base 100. The substrate 100 may be any suitable substrate known to those skilled in the art, for example, it may be at least one of the following materials: silicon (Si), germanium (Ge), silicon germanium (SiGe), carbon Silicon (SiC), carbon germanium silicon (SiGeC), indium arsenide (InAs), gallium arsenide (GaAs), indium phosphide (InP) or other III/V compound semiconductors, including multilayer structures composed of these semiconductors, etc. , Or silicon-on-insulator (SOI), silicon-on-insulator (SSOI), silicon germanium-on-insulator (S-SiGeOI), silicon germanium-on-insulator (SiGeOI), and germanium-on-insulator (GeOI), or Double-Side Polished Wafers (DSP) can also be ceramic substrates such as alumina, quartz or glass substrates. The material of the etching protection layer 101 can be any suitable dielectric material, including but not limited to at least one of silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, and the like. The etching protection layer On the one hand, it can be used to increase the structural stability of the final bulk acoustic wave resonator, increase the isolation between the bulk acoustic wave resonator and the substrate 100, and reduce the resistivity requirements of the substrate 100. On the other hand, it can also be used in the manufacture of During the process of the acoustic wave resonator, other areas of the substrate are protected from etching, thereby improving the performance and reliability of the device.

A cavity 102 is formed between the bottom electrode layer 104 and the substrate. 1A to 1C, in this embodiment, the cavity 102 can be formed by sequentially etching the etching protection layer 101 and a part of the thickness of the substrate 100 through an etching process, forming a whole bottom recessed The groove structure in the substrate. However, the technology of the present invention is not limited to this. Please refer to FIG. 2E. In another embodiment of the present invention, the cavity 102 may also be formed by passing a sacrificial layer protruding on the surface of the etching protection layer 101. The removal process is formed above the top surface of the etching protection layer 101 to form a cavity structure protruding on the surface of the etching protection layer 101 as a whole. In addition, in this embodiment, the shape of the bottom surface of the cavity 102 is rectangular, but in other embodiments of the present invention, the shape of the bottom surface of the cavity 102 may also be a circle, an ellipse, or a polygon other than a rectangle, such as five Hexagons, hexagons, etc.

The piezoelectric resonant layer 1051 can also be called a piezoelectric resonator, and is located in the upper region of the cavity 102 (in other words, located in the region of the cavity 102), corresponding to the effective working area of the bulk acoustic wave resonator, And the piezoelectric resonance layer 1051 is disposed between the bottom electrode layer 104 and the top electrode layer 108. The bottom electrode layer 104 includes a bottom electrode lap portion 1040, a bottom electrode protrusion 1041, and a bottom electrode resonance portion 1042 that are sequentially connected, and the top electrode layer 108 includes a top electrode lap portion 1080, a top electrode recess 1081, and a top electrode The electrode resonance part 1082, the bottom electrode resonance part 1042, the top electrode resonance part 1082 all overlap the piezoelectric resonance layer 1051, and the cavity 102 overlaps the bottom electrode resonance part 1042, the piezoelectric resonance layer 1051, and the top electrode The area corresponding to the resonance part 1082 constitutes the effective working area 102A of the bulk acoustic wave resonator. The cavity 102 except for the effective working area 102A is the ineffective area 102B. The piezoelectric resonance layer 1051 is located in the effective working area 102A and is connected to the cavity. The separation of the film layer around 102 can completely limit the effective working area of the bulk acoustic wave resonator in the area of the cavity 102, and can reduce the influence of the film layer around the cavity on the longitudinal vibration generated by the piezoelectric resonant layer and reduce the invalidity. The parasitic parameters generated in the area 102B improve device performance. The bottom electrode resonant portion 1042, the piezoelectric resonant layer 1051, and the top electrode resonant portion 1082 are all flat structures with flat upper and lower surfaces. The bottom electrode protruding portion 1041 is located above the cavity 102B on the periphery of the effective working area 102A and is electrically connected. The bottom electrode resonant part 1042 is connected and protrudes away from the bottom surface of the cavity. The top electrode recess 1081 is located above the cavity 102B outside the effective working area 102A and is electrically connected to the top electrode The resonant part 1082 is convex in a direction away from the bottom surface of the cavity 102. The bottom electrode convex portion 1041 is generally higher than the top surface of the bottom electrode resonant portion 1042, and the top electrode concave portion 1081 is generally lower than the top surface of the top electrode resonant portion 1082. The top electrode concave portion 1081 and the bottom electrode convex The raised portions 1041 are all located in the cavity area (ie 102B) on the periphery of the piezoelectric resonance layer 1051. The bottom electrode protruding portion 1041 and the top electrode recess portion 1081 can be a solid structure or a hollow structure, preferably a hollow structure, so that the film thickness of the bottom electrode layer 104 and the top electrode layer 108 can be made uniform, and a solid bottom can be avoided. The gravity of the electrode protrusion 1041 causes the bottom electrode resonance part 1042 and the piezoelectric resonance layer 1051 to separate, and avoids the solid top electrode recess 1081 from causing the top electrode resonance part 1082 and the piezoelectric resonance layer 1051 and bottom electrode resonance part below The 1042 bed deforms, which further improves the resonance factor. Wherein, the bottom electrode resonant portion 1042 and the top electrode resonant portion 1082 are both polygonal (both the top surface and the bottom surface are polygonal), and the shape of the bottom electrode resonant portion 1042 and the top electrode resonant portion 1082 may be similar (As shown in Figures 2A-2B and 2D) or exactly the same (as shown in Figures 1A and 2C). The piezoelectric resonance layer 1051 has a polygonal structure similar to the shape of the bottom electrode resonance portion 1042 and the top electrode resonance portion 1082.

1A to 1C, in this embodiment, the bottom electrode layer 104, the piezoelectric resonance layer 1051, and the top electrode layer 108 form a "watch"-shaped film structure, and the bottom electrode overlap portion 1040 and the bottom electrode resonate One corner of the part 1042 is aligned, one corner of the top electrode overlapping part 10840 and the top electrode resonant part 1082 are aligned, the bottom electrode overlapping part 1040 and the top electrode overlapping part 10840 are equivalent to the two straps of a "watch". The bottom electrode protruding portion 1041 is arranged along the side of the bottom electrode resonating portion 1042 and is only provided in the area where the bottom electrode overlapping portion 1040 and the bottom electrode resonating portion 1042 are aligned. The top electrode recessed portion 1081 It is arranged along the edge of the top electrode resonance portion 1082 and is only arranged in the area where the top electrode lap portion 1080 and the top electrode resonance portion 1082 are aligned, the bottom electrode protrusion 1041 and the top electrode The recessed portion 1081 is equivalent to the connection structure between the dial of the "watch" and the two straps. The bottom electrode resonant portion 1042 in the effective area 102A is the piezoelectric resonant layer 1051 and the top electrode resonant portion 1082 stacked structure is equivalent to the dial of a watch Except for the part of the dial that is connected to the film layer on the substrate surrounding the cavity, the rest of the dial is separated from the film layer on the substrate surrounding the cavity through the cavity. That is, in this embodiment, the bottom electrode convex portion 1041 and the top electrode concave portion 1081 both extend around the peripheral direction of the piezoelectric resonance layer 1051, and the bottom electrode convex portion 1041 and the top electrode The depressions 1081 only surround part of the piezoelectric resonance layer 1051 in the peripheral direction of the piezoelectric resonance layer 1051, and with reference to the plane where the piezoelectric resonance layer 1051 is located, the top electrode depression 1081 and the bottom The electrode protrusions 1041 are located on both sides of the piezoelectric resonant layer 1051 and are completely opposite to each other, so that while achieving a certain transverse wave blocking effect, it can be beneficial to the ineffective area not covered by the top electrode lap 1080 and the bottom electrode lap 1040. The reduction of the area of 102B is beneficial to the reduction of the device size, and at the same time, it is also beneficial to reduce the area of the top electrode overlap portion 1080 and the bottom electrode overlap portion 1040 to further reduce parasitic parameters and improve the electrical performance of the device. The bottom electrode lap portion 1040 is electrically connected to the side of the bottom electrode protrusion 1041 facing away from the bottom electrode resonance portion 1042, and is suspended from the bottom electrode protrusion 1041 on the bottom electrode protrusion. The cavity (ie 102B) outside the starting portion 1041 extends above the partial etching protection layer 101 on the periphery of the cavity 102; the top electrode lap portion 1080 is electrically connected to the top electrode recessed portion 1081 facing away One side of the top electrode resonant portion 1082, and extends from the top electrode recessed portion 1081 through the cavity (that is, 102B) outside the top electrode recessed portion 1081 to the periphery of the cavity 102 Partially etch over the protective layer 101; the bottom electrode overlap portion 1040 and the top electrode overlap portion 1080 extend above the substrate outside the two opposite sides of the cavity 102, and the bottom electrode overlaps The connecting portion 1040 and the top electrode overlapping portion 1080 are staggered in the cavity 102 area (that is, the two do not overlap), thereby reducing parasitic parameters and avoiding the bottom electrode overlapping portion and the top electrode overlapping portion Leakage, short circuit and other problems caused by contact can improve device performance. The bottom electrode lap portion 1040 can be used to connect a corresponding signal line to transmit a corresponding signal to the bottom electrode resonance portion 1042 through the bottom electrode protrusion 1041, and the top electrode lap portion 1080 can be used to connect a corresponding signal line. The signal line transmits the corresponding signal to the top electrode resonator 1082 through the top electrode recess 1081, so that the bulk acoustic wave resonator can work normally, specifically, through the bottom electrode lap 1040 and the top electrode lap 1080 respectively to The bottom electrode resonance part 1042 and the top electrode resonance part 1082 apply a time-varying voltage to excite the longitudinal extension mode or "piston" mode. The piezoelectric resonance layer 1051 converts energy in the form of electrical energy into longitudinal waves, and parasitic transverse waves are generated in the process. The bottom electrode protrusions 1041 and the top electrode recesses 1081 can block these transverse waves from propagating into the film around the cavity, and confine them within the cavity 102, thereby avoiding energy loss caused by transverse waves and improving the quality factor.

Preferably, the line widths of the top electrode recess 1081 and the bottom electrode protrusion 1041 are the minimum line width allowed by the corresponding process, the horizontal distance between the bottom electrode protrusion 1041 and the piezoelectric resonance layer 1051, and the top electrode The horizontal distance between the recessed portion 1081 and the piezoelectric resonance layer 1051 is the minimum distance allowed by the corresponding process, thereby enabling the top electrode recessed portion 1081 and the bottom electrode convex portion 1041 to achieve a certain transverse wave blocking effect. , Can help reduce the device area.

In addition, the sidewalls of the top electrode recess 1081 are inclined sidewalls relative to the top surface of the piezoelectric resonance layer. As shown in FIG. 1B, the cross section of the top electrode recess 1081 along the line XX' in FIG. 1A is Trapezoid or trapezoid-like, the angles β1 and β2 between the two sidewalls of the top electrode recess 1081 and the top surface of the piezoelectric resonance layer 1051 are both less than or equal to 45 degrees, thereby avoiding the top electrode from sinking The sidewalls of the portion 1081 are too vertical, causing the top electrode recess 1081 to break, thereby affecting the effect of transmitting signals to the top electrode resonance portion 1082, and at the same time, it can also improve the thickness uniformity of the entire top electrode layer 108; The sidewalls of the raised portion 1041 are inclined sidewalls relative to the bottom surface of the piezoelectric resonant layer. As shown in FIG. 1B, the cross-section of the bottom electrode protrusion 1041 along the line XX' in FIG. 1A is trapezoidal or trapezoidal, so The angles α1 and α2 between the two side walls of the bottom electrode protrusion 1041 and the bottom surface of the piezoelectric resonant layer 1051 are all less than or equal to 45 degrees, thereby avoiding the impact of the bottom electrode protrusion 1041 The sidewalls are too vertical to cause the bottom electrode layer 104 to break, thereby affecting the effect of transmitting signals to the bottom electrode resonator portion 1042, and at the same time, the thickness uniformity of the bottom electrode layer 104 can be improved.

In a preferred embodiment of the present invention, the bottom electrode resonant portion 1042, the bottom electrode protruding portion 1041, and the bottom electrode overlap portion 1040 are formed by the same film layer manufacturing process (ie, the same film layer manufacturing process), and the top electrode resonates The portion 1082, the top electrode recessed portion 1081, and the top electrode overlap portion 1080 are formed using the same film layer manufacturing process (that is, the same film layer manufacturing process), that is, the bottom electrode resonance portion 1042, the bottom electrode convex portion 1041 and the bottom electrode overlap portion The connecting portion 1040 is an integrated film layer, and the top electrode resonance portion 1082, the top electrode recess 1081 and the top electrode overlap portion 1080 are an integrated film layer, which can simplify the process and reduce the cost. The film material used to make the bottom electrode resonator portion 1042, the bottom electrode convex portion 1041, and the bottom electrode lap portion 1040, and the film layer material used to make the top electrode resonator portion 1082, the top electrode recess portion 1081, and the top electrode lap portion 1080 Any suitable conductive material or semiconductor material well known in the art can be used respectively, wherein the conductive material can be a metal material with conductive properties, for example, aluminum (Al), copper (Cu), platinum (Pt), gold ( One or more of Au), molybdenum (Mo), tungsten (W), iridium (Ir), osmium (Os), rhenium (Re), palladium (Pd), rhodium (Rh) and ruthenium (Ru), The semiconductor material is for example Si, Ge, SiGe, SiC, SiGeC, etc. In other embodiments of the present invention, the bottom electrode resonator portion 1042, the bottom electrode protrusion portion 1041, and the bottom electrode overlap portion 1040 can also be formed by using different film production processes under the premise that the process cost and the process technology permit. The top electrode resonance portion 1082, the top electrode recess portion 1081, and the top electrode lap portion 1080 can be formed by using different film production processes.

2A to 2D, in order to further improve the shear wave blocking effect, the bottom electrode protrusion 1041 extends to more continuous sides of the bottom electrode resonance part 1042, and the top electrode recess 1081 extends to more continuous edges of the top electrode resonance part 1082 When the bottom electrode convex portion 1041 and the top electrode concave portion 1081 overlap, please refer to FIG. 2F, there is a gap H between them, so that there is no gap between the top electrode layer 108 and the bottom electrode layer 104. Electrical contact to avoid short circuit problems. For example, referring to FIG. 2A, the projections of the bottom electrode protrusions 1041 and the top electrode recesses 1081 on the bottom surface of the cavity 102 can be just or close to each other, that is, the bottom electrode protrusions 1041 and the top electrode recesses 1081 are in The projection on the bottom surface of the cavity 102 can form a completely closed ring or close to a closed ring. Therefore, the cooperation of the bottom electrode protrusion 1041 and the top electrode recess 1081 can perform transverse waves on the entire periphery of the piezoelectric resonance layer 1051. In this case, the projection size of the bottom electrode protrusion 1041 and the top electrode recess 1081 on the bottom surface of the cavity 102 can be equally divided into the ring formed by the combination of the two (the bottom electrode protrusion 1041 and the top electrode The electrode recess 1081 is located on both sides of the piezoelectric resonance layer 1051 and all parts are completely opposite), or it can be unevenly divided (the bottom electrode protrusion 1041 and the top electrode recess 1081 are located on both sides of the piezoelectric resonance layer 1051 and only Some relatives). For another example, referring to FIG. 2B, the piezoelectric resonance layer 1051, the top electrode resonance portion 1082, and the bottom electrode resonance portion 1042 are all pentagonal planar structures, and the area of the piezoelectric resonance layer 1051 is the smallest, and the top electrode resonance portion 1082 times The area of the bottom electrode resonance portion 1042 is the largest. The bottom electrode protrusions 1041 are arranged along and connected to each side of the bottom electrode resonance portion 1042, and the bottom electrode protrusions 1041 are on the bottom surface of the cavity 102 The projection of the top electrode recessed portion 1081 is partially or fully projected on the bottom surface of the cavity 102, and the top electrode recessed portion 1081 is along the top electrode resonant portion 1082. Each side is arranged and connected to each side, and the projection of the top electrode recess 1081 on the bottom surface of the cavity 102 exposes the boundary where the bottom electrode protrusion 1041 is connected by the bottom electrode overlap portion 1040 in the cavity 102 Part or all of the projection on the bottom surface of the bottom electrode, so that the bottom electrode protrusion 1041 and the top electrode overlap portion 1080 do not overlap, and the top electrode recess 1081 does not overlap the bottom electrode overlap portion 1040, thereby reducing parasitic parameters. In addition, the bottom electrode convex portion 1041 and the top electrode concave portion 1081 can be staggered a little bit (the overlapping part is not in contact) or even completely. That is, at this time, the bottom electrode convex portion 1041 and the top electrode concave portion 1081 are perpendicular to the piezoelectric The direction of the resonance layer 1051 will be partially aligned up and down but not in contact or completely staggered, but all parts are opposed in the peripheral direction of the piezoelectric resonance layer 1051, so that the bottom electrode is convex in the projection structure toward the bottom of the cavity The portion 1041 can partially surround the top electrode recess 1081. In this way, not only the cooperation of the bottom electrode protrusion 1041 and the top electrode recess 1081 can block the entire periphery of the piezoelectric resonance layer 1051, but also can reduce the bottom The alignment requirements of the electrode protruding portion 1041 and the top electrode recessed portion 1081 are beneficial to reduce the manufacturing difficulty. For another example, referring to FIG. 2C, the piezoelectric resonance layer 1051, the top electrode resonance portion 1082, and the bottom electrode resonance portion 1042 are all pentagonal planar structures, and the area of the piezoelectric resonance layer 1051 is the smallest, and the top electrode resonance portion 1082 and The area and shape of the bottom electrode resonance portion 1042 are the same or substantially the same. The bottom electrode protrusion 1041 surrounds the bottom electrode resonance portion 1042, the top electrode recess 1081 surrounds the top electrode resonance portion 1082, and the bottom electrode protrusion 1041 The projections of the top electrode recessed portion 1041 and the top electrode recessed portion 1081 on the bottom surface of the cavity 102 coincide, and the projections of the top electrode resonant portion 1082 and the bottom electrode resonant portion 1042 on the bottom surface of the cavity 102 coincide. Therefore, different heights in the vertical direction can be passed. The bottom electrode convex portion 1041 and the top electrode concave portion 1081 are both in a closed ring shape to block transverse waves of different heights generated by the piezoelectric resonance layer 1051. That is, when the bottom electrode convex portion 1041 extends to more continuous sides of the bottom electrode resonant portion 1042, and the top electrode concave portion 1081 extends to more continuous sides of the top electrode resonant portion 1082, the bottom electrode convex The raised portion 1041 and the top electrode recessed portion 1081 both extend around the peripheral direction of the piezoelectric resonance layer 1051, and the bottom electrode raised portion 1041 and the top electrode recessed portion 1081 are respectively along the piezoelectric resonance layer 1051. Partially surround the periphery of the piezoelectric resonance layer 1051 in the peripheral direction (as shown in FIGS. 2A-2B). At this time, the top electrode concave portion 1081 and the bottom electrode convex portion 1041 are at least partially opposed, or, The bottom electrode convex portion 1041 and the top electrode concave portion 1081 respectively surround the piezoelectric resonance layer 1051 in the peripheral direction of the piezoelectric resonance layer 1051 (as shown in FIG. 2C). At this time, the top electrode is concave All parts of the portion 1081 and the bottom electrode protrusion 1041 are opposite to each other.

2A to 2D, in these embodiments of the present invention, the bottom electrode lap portion 1040 is electrically connected to at least one side or at least one side of the bottom electrode protrusion 1041 facing away from the bottom electrode resonance portion 1042 Angle, and extend from the corresponding side of the bottom electrode protrusion 1041 over the cavity (that is, 102B) outside the bottom electrode protrusion 1041 to the part of the periphery of the cavity 102 for etching protection Above the layer 101; the top electrode lap portion 1080 is electrically connected to at least one side or at least one corner of the top electrode recessed portion 1081 facing away from the top electrode resonant portion 1082, and from the top electrode recessed portion 1081 After being suspended above the cavity (ie 102B) outside the top electrode recess 1081, it extends to above the partial etching protection layer 101 on the periphery of the cavity 102, and the top electrode overlap portion 1080 and the bottom The projections of the electrode overlap portion 1040 on the bottom surface of the cavity 102 may be exactly connected or separated from each other. Therefore, the top electrode overlap portion 1080 and the bottom electrode overlap portion 1040 are in the cavity 102. There is no overlap in the areas and they are staggered. For example, as shown in FIGS. 1A and 2A to 2C, the bottom electrode overlap portion 1040 may only extend above a part of the substrate around one side of the cavity 102, and the top electrode overlap portion 1080 only extends to the Above the part of the substrate surrounding one side of the cavity 102, and the projections of the top electrode overlap portion 1080 and the bottom electrode overlap portion 1040 on the bottom surface of the cavity 102 are separated from each other, thereby avoiding When the top electrode overlap portion 1080 and the bottom electrode overlap portion 1040 overlap, parasitic parameters and possible leakage and short circuit problems are introduced. However, preferably, referring to FIG. 2D, when the bottom electrode protruding portion 1041 is arranged along multiple consecutive sides of the bottom electrode resonance portion 1042, the bottom electrode overlapping portion 1040 protrudes along the bottom electrode. The raised portion 1041 is arranged away from all sides of the bottom electrode resonance portion 1042 and continuously extends to the substrate on the periphery of the cavity 102, thereby enabling the bottom electrode overlap portion 1040 to extend to the periphery of the cavity 102 Part of the substrate in more directions, that is, at this time, the bottom electrode overlap portion 1040 completely covers the cavity 102 above the cavity portion where it is located, so that a large area bottom electrode overlap portion 1040 can pass through The laying to enhance the supporting force of the membrane layer of the effective working area 102A and prevent the cavity 102 from collapsing. Further preferably, when the bottom electrode overlap portion 1040 extends above a part of the substrate in more directions on the periphery of the cavity 102, the top electrode overlap portion 1080 only extends to the cavity 102 Above a part of the substrate in one direction of the periphery, for example, when the top-view shape of the cavity 102 is rectangular, the top electrode overlap portion 1080 only extends above the substrate on one side of the cavity 102, and the bottom electrode overlaps The portion 1040 extends to the other three sides of the cavity 102, and at this time, the projections of the top electrode overlapping portion 1080 and the bottom electrode overlapping portion 1040 on the bottom surface of the cavity 102 just meet Or separate from each other, that is, at this time, the bottom electrode overlap portion 1040 completely covers the cavity 102 above the cavity part where it is located, and is in the width direction of the top electrode overlap portion 1080, and the top electrode The overlap portion 1080 does not overlap, thereby avoiding that the arrangement of the large-area top electrode overlap portion will overlap with the bottom electrode overlap portion and other structures in the vertical direction and introduce excessive parasitic parameters, which can further improve the electrical performance of the device And reliability.

In various embodiments of the present invention, when the top-view shape of the cavity 102 is a polygon, the bottom electrode lap portion 1040 and the top electrode lap portion 1080 respectively expose at least one side of the cavity, thereby making At least one end of the bottom electrode resonant portion 1042 connected to the bottom electrode protrusion 1041 and the top electrode resonant portion 1082 connected to the top electrode recess 1081 is completely suspended, which can help reduce the area of the ineffective region 102B, and thus Parasitic parameters such as parasitic capacitance generated in the invalid region 102B are reduced, and device performance is improved. Preferably, the bottom electrode protrusion 1041 is at least offset from the top electrode overlap portion 1080 above the cavity 102 (that is, the two do not overlap in the cavity area), and the top electrode recess 1081 is The upper portion of the cavity 102 and the bottom electrode overlapping portion 1040 are at least staggered (that is, the two do not overlap in the cavity area), and the top electrode recessed portion 1081 and the bottom electrode raised portion 1041 are in the cavity. The projections on the bottom surface of the cavity 102 are exactly connected or staggered or only partially overlapped, thereby further reducing parasitic parameters such as parasitic capacitance generated in the invalid region 102B, and improving device performance.

It should be noted that, in order to achieve the best transverse wave blocking effect and facilitate the manufacture of small-sized devices, the closer the top electrode recess 1081 and the bottom electrode protrusion 1041 are to the effective working area 102A, the better. The top electrode recess 1081 and the bottom electrode The line width of the electrode protrusions 1041 is as small as possible. Preferably, the line widths of the top electrode recesses 1081 and the bottom electrode protrusions 1041 are the minimum line widths allowed by the corresponding process, respectively. The horizontal distance between the electrode protrusion 1041 and the effective working area 102A (that is, the piezoelectric resonance layer 1051) is the minimum distance allowed by the corresponding process, respectively.

It is worth noting that, in the foregoing embodiments, the top electrode resonance portion 1082 and the bottom electrode resonance portion 1042 have similar shapes or the same shape and the same area, or the area of the bottom electrode resonance portion 1042 is larger than the area of the top electrode resonance portion 1082, but the present invention The technical solution is not limited to this. In other embodiments of the present invention, the shapes of the top electrode resonant portion 1082 and the bottom electrode resonant portion 1042 may not be similar, but preferably, the top electrode recessed portion 1081 and the bottom electrode convex The shape of the raised portion 1041 is preferably adapted to the shape of the piezoelectric resonance layer 1051, and it can extend along at least one side of the piezoelectric resonance layer 1051. In addition, our research has found that most of the parasitic transverse waves of the bulk acoustic wave resonator will be transmitted through the connection structure between the film layer on the effective working area 102A and the substrate at the periphery of the cavity. Therefore, in the various embodiments of the present invention, Under the premise of ensuring that the film layer of the effective working area 102A can be effectively supported, the area (or line width) of the top electrode lap portion 1080 can be minimized, and the area (or line width) of the bottom electrode lap portion 1040 can be minimized. The smallest.

An embodiment of the present invention also provides a filter including at least one bulk acoustic wave resonator as described in any of the foregoing embodiments of the present invention.

An embodiment of the present invention also provides a radio frequency communication system, including at least one filter according to an embodiment of the present invention.

Please refer to FIG. 3, an embodiment of the present invention also provides a method for manufacturing a bulk acoustic wave resonator (such as the bulk acoustic wave resonator shown in FIGS. 1A to 2D) of the present invention, including:

S1, providing a substrate, and forming a first sacrificial layer with sacrificial protrusions on part of the substrate;

S2, forming a bottom electrode layer on the first sacrificial layer, and a portion of the bottom electrode layer covering the surface of the sacrificial protrusion forms a bottom electrode protrusion;

S3, forming a piezoelectric resonance layer on the bottom electrode layer, the piezoelectric resonance layer exposing the bottom electrode protrusions;

S4, forming a second sacrificial layer with a first groove in the exposed area around the piezoelectric resonance layer;

S5, forming a top electrode layer on the piezoelectric resonant layer and part of the second sacrificial layer around the piezoelectric resonant layer, and the part of the top electrode layer covering the first groove forms a top electrode recess;

S6, removing the second sacrificial layer and the first sacrificial layer with sacrificial protrusions, and the positions of the second sacrificial layer and the first sacrificial layer with sacrificial protrusions form a cavity.

1A, 1B and FIGS. 4A to 4B, in step S1 of this embodiment, the first sacrificial layer is formed on a part of the substrate by etching the substrate to form a groove and filling the groove with material. The realization process includes:

First, referring to FIGS. 1A and 4A, a substrate is provided, specifically, a substrate 100 is provided, and an etching protection layer 101 is covered on the substrate 100. Wherein, the etching protection layer 101 can be formed on the substrate 100 by any suitable process method, such as thermal oxidation, thermal nitridation, thermal oxynitriding, or other heat treatment methods, or chemical vapor deposition, physical vapor deposition, or atomic layer deposition. on. Further, the thickness of the etching protection layer 101 can be set reasonably according to actual device process requirements, and is not specifically limited here.

Next, please continue to refer to FIGS. 1A, 1B and 4A to etch the substrate through photolithography and etching processes to form at least one second groove 102'. The etching process can be a wet etching or a dry etching process, and a dry etching process is preferably used. Dry etching includes but not limited to reactive ion etching (RIE), ion beam etching, plasma Body etching or laser cutting. The depth and shape of the second groove 102' depend on the depth and shape of the cavity required for the bulk acoustic wave resonator to be manufactured, and the cross-sectional shape of the second groove 102' is rectangular. In other embodiments of the present invention The cross section of the second groove 102' may also be any other suitable shape, for example, a circle, an ellipse, or other polygons (such as pentagons, hexagons, etc.) other than rectangles.

Then, referring to FIGS. 1A, 1B, and 4B, the first sacrificial layer 103 can be filled in the second groove 102' by vapor deposition, thermal oxidation, spin coating, or epitaxial growth. The first sacrificial layer 103 can be selected as a semiconductor material, dielectric material, or photoresist material that is different from the substrate 100 and the etch protection layer 101. For example, when the substrate 100 is a Si substrate, the first sacrificial layer 103 can be Ge. The sacrificial layer 103 may also cover the etching protection layer 101 on the periphery of the groove or the top surface is higher than the top surface of the etching protection layer 101 around the groove; then, through a chemical mechanical planarization (CMP) process, the second The top of a sacrificial layer 103 is planarized to the top surface of the etching protection layer 101, so that the first sacrificial layer 103 is only located in the second groove 102', and the top surface of the first sacrificial layer 103 It is flush with the top surface of the surrounding etching protection layer 101, thereby providing a flat process surface for subsequent processes.

Next, a sacrificial material layer (not shown) can be covered on the first sacrificial layer 103 by a suitable process such as a coating process or a vapor deposition process. The thickness of the sacrificial material layer depends on the thickness of the bottom electrode protrusions formed subsequently. The protrusion height, the material of the sacrificial material layer can be selected from amorphous carbon, photoresist, dielectric materials (such as silicon nitride, silicon oxycarbide, porous materials, etc.) or semiconductor materials (such as polysilicon, amorphous silicon, germanium) ), etc.; then, the sacrificial material layer is patterned by a photolithography process or a photolithography combined etching process to form a sacrificial protrusion 103', and the line width and size of the sacrificial protrusion 103' , The shape and position determine the line width, size, shape and position of the bottom electrode protrusion to be formed later. In this embodiment, the longitudinal cross-section of the sacrificial protrusion 103' along XX′ in FIG. 2A is a trapezoid with a narrow upper and a wide bottom, and the sidewall of the sacrificial protrusion 103' is sandwiched between the top surface of the first sacrificial layer 103 angle

It is less than 45 degrees, thereby facilitating the deposition of the subsequent bottom electrode material layer, thereby improving the thickness uniformity of the subsequently formed bottom electrode layer in the region of the second groove 102'. In other embodiments of the present invention, the cross-sectional shape of the sacrificial protrusion 103' can also be a spherical cap with a narrow upper and a wide bottom, that is, its longitudinal cross-section along the line XX' of FIG. 1A is an inverted U shape. The horizontal distance between the sacrificial protrusion 103' and the effective working area 102A is preferably the minimum distance allowed by the etching alignment process of the sacrificial protrusion 103', and the line width of the sacrificial protrusion 103' corresponds to The minimum line width allowed by the process.

In other embodiments of the present invention, the sacrificial protrusion 103' and the first sacrificial layer 103 can be formed by the same process, for example, the first sacrificial layer 103 is covered on the second groove 102' and the etching protection layer 101 first. The thickness of the first sacrificial layer 103 is not less than the sum of the depth of the second groove 102' and the thickness of the sacrificial protrusion 103'; then, the first sacrificial layer 10 is patterned by an etching process to form only filling The first sacrificial layer 103 in the second groove 102', and part of the first sacrificial layer 103 has sacrificial protrusions 103', the bottom surface of the sacrificial protrusion 103' may be flush with the top of the etching protection layer 101 The top surface of the remaining part of the first sacrificial layer 103 is flush with the top surface of the etching protection layer 101.

1A, 1B, and 4D, in step S2, first, a suitable method can be selected according to the material of the bottom electrode to be formed on the surface of the etching protection layer 101, the first sacrificial layer 103, and the sacrificial protrusion 103' Covering the bottom electrode material layer (not shown), for example, the bottom electrode material layer can be formed by magnetron sputtering, vapor deposition or other physical vapor deposition or chemical vapor deposition methods; then, a photolithography process is used to form a definition on the bottom electrode material layer A photoresist layer (not shown) with a bottom electrode pattern is then used as a mask to etch the bottom electrode material layer to form a bottom electrode layer (that is, the remaining bottom electrode material layer) 104, After that, the photoresist layer is removed. The bottom electrode material layer can use any suitable conductive material or semiconductor material well known in the art, where the conductive material can be a metal material with conductive properties, for example, aluminum (Al), copper (Cu), platinum (Pt) , Gold (Au), molybdenum (Mo), tungsten (W), iridium (Ir), osmium (Os), rhenium (Re), palladium (Pd), rhodium (Rh) and ruthenium (Ru) or There are several kinds of semiconductor materials such as Si, Ge, SiGe, SiC, SiGeC, etc. In this embodiment, the bottom electrode layer (the remaining bottom electrode material layer) 104 includes a bottom electrode resonant portion 1042 that covers the effective working area 102A formed subsequently, and a bottom electrode bump 1041 that covers the sacrificial bump 103' , From the side of the bottom electrode protrusion 1041 through the surface of the first sacrificial layer 103 to the outside of the second groove 102', the bottom electrode overlap portion 1040 and the bottom electrode resonant portion 1042 on the etching protection layer 101 , The bottom electrode peripheral portion 1043 separated from the bottom electrode protrusions 1041, the bottom electrode peripheral portion 1043 can be connected to the side of the bottom electrode protrusion 1041 away from the bottom electrode resonance portion 1042 to be used as the area to be formed A metal contact of the bulk acoustic wave resonator can also be separated from the bottom electrode overlap portion 1040 to serve as a part of the bottom electrode overlap portion of the adjacent bulk acoustic wave resonator. In other embodiments of the present invention, the outer periphery of the bottom electrode Section 1043 can be omitted. The top-view shape of the bottom electrode resonator portion 1042 may be a pentagon. In other embodiments of the present invention, it may also be a quadrilateral or a hexagon. The bottom electrode protrusion 1041 is provided on the bottom electrode overlap portion 1040 and the bottom electrode. Between the resonance parts 1042, the bottom electrode protrusion 1041 is arranged along at least one side of the bottom electrode resonance part 1042 and is connected to a corresponding side of the bottom electrode resonance part 1042, and the bottom electrode overlap part 1040 is electrically connected to at least one side or at least one corner of the bottom electrode protruding portion 1041 facing away from the bottom electrode resonance portion 1042, and covers the bottom electrode from the corresponding side of the bottom electrode protruding portion 1041 The top surface of the first sacrificial layer 103 outside the convex portion 1041 extends to the top surface of the partial etching protection layer 101 outside the second groove 102', that is, the bottom electrode convex portion 1041 extends along the The sides of the bottom electrode resonance portion 1042 are arranged and at least arranged in the area where the bottom electrode overlap portion 1040 and the bottom electrode resonance portion 1042 are aligned. For example, the bottom electrode protrusion 1041 may surround the bottom electrode The resonant part 1042 makes a circle to form a closed-loop structure (please refer to FIG. 2C). It can also be arranged along only one side of the bottom electrode resonant part 1042, or it can be continuous along the bottom electrode resonant part 1042. An open-loop structure with two or more consecutive sides (please refer to Figures 2A-2B and 2D). The shape, line width, and horizontal distance between the bottom electrode protrusion 1041 and the effective working area 102A all depend on the molding process of the sacrificial protrusion 103'. Preferably, as shown in FIG. 2D, the bottom electrode overlap portion 1040 completely covers the cavity 102 above the cavity part where it is located, and overlaps with the top electrode in the width direction of the top electrode overlap portion 1080. The connecting portion 1080 has no overlap, so as to improve the supporting force for the subsequent film layer, and try to avoid introducing unnecessary parasitic parameters by overlapping with the top electrode overlap portion 1080. For example, when the top-view shape of the second groove 102' is rectangular At this time, the bottom electrode overlapping portion 1040 extends to three sides of the rectangle. The bottom electrode resonance part 1042 may be used as an input electrode or an output electrode that receives or provides an electric signal such as a radio frequency (RF) signal. In this embodiment, the bottom electrode protruding portion 1041 and the bottom electrode resonance portion 1042, the bottom electrode overlapping portion 1040 have substantially the same thickness.

1A, 1B and 4E, in step S3, first, any suitable method known to those skilled in the art such as chemical vapor deposition, physical vapor deposition or atomic layer deposition can be used to deposit the piezoelectric material layer 105; , Using a photolithography process to form a photoresist layer (not shown) defining a piezoelectric film pattern on the piezoelectric material layer 105, and then use the photoresist layer as a mask to etch the piezoelectric material layer 105, To form the piezoelectric resonance layer 1051, after that, the photoresist layer is removed. The piezoelectric material layer 105 may be made of aluminum nitride (AlN), zinc oxide (ZnO), lead zirconate titanate (PZT), lithium niobate (LiNbO ₃ ), quartz (Quartz), potassium niobate (KNbO) ₃ ) or lithium tantalate (LiTaO ₃ ) and other piezoelectric materials with wurtzite crystal structure and their combinations. When the piezoelectric material layer 105 includes aluminum nitride (AlN), the piezoelectric material layer 105 may further include rare earth metals, such as at least one of scandium (Sc), erbium (Er), yttrium (Y), and lanthanum (La). Kind. In addition, when the piezoelectric material layer 105 includes aluminum nitride (AlN), the piezoelectric material layer 105 may also include transition metals, such as zirconium (Zr), titanium (Ti), manganese (Mn), and hafnium (Hf). At least one. The piezoelectric material layer 105 remaining after patterning includes a piezoelectric resonance layer 1051 and a piezoelectric peripheral portion 1050 separated from each other. The piezoelectric resonance layer 1051 is located on the bottom electrode resonance portion 1042, exposing the bottom electrode convex portion 1041, and can The bottom electrode resonance part 1042 is completely or partially covered. The shape of the piezoelectric resonant layer 1051 can be the same as or different from the shape of the bottom electrode resonator 1042, and its top-view shape can be a pentagon or other polygons, such as a quadrilateral, a hexagon, a heptagon, or an octagon.形等。 Shape and so on. A gap can be formed between the piezoelectric peripheral portion 1050 and the piezoelectric resonance layer 1051 to expose the bottom electrode protruding portion 1041 and the first sacrificial layer 103 around the bottom electrode resonance portion 1042, and is further restricted by the formed gap The subsequent formation area of the second sacrificial layer provides a relatively flat process surface for the subsequent formation of the second sacrificial bump. The piezoelectric peripheral portion 1050 can also realize the difference between the subsequently formed top electrode peripheral portion and the previously formed bottom electrode peripheral portion 1043. It also provides a relatively flat process surface for the subsequent formation of the second sacrificial layer and the top electrode layer.

1A, 1B and 4F, in step S4, first, the piezoelectric peripheral portion 1050, the piezoelectric resonance layer 1051, and the piezoelectric peripheral portion 1050 and The gap between the piezoelectric resonance layer 1051 covers the second sacrificial layer 106, and the second sacrificial layer 106 can fill the gap between the piezoelectric peripheral portion 1050 and the piezoelectric resonance layer 1051. The material of the second sacrificial layer 106 It can be selected from at least one of amorphous carbon, photoresist, dielectric materials (such as silicon nitride, silicon oxycarbide, porous materials, etc.) or semiconductor materials (such as polysilicon, amorphous silicon, germanium), etc., and the second The material of the sacrificial layer 106 is preferably different from that of the first sacrificial layer 103, in order to be able to use the top surface of the first sacrificial layer 103 as an etching stop point in the subsequent etching process of forming the first groove 107 to control the subsequent formation The depth of the first groove 107; then, the top of the second sacrificial layer 106 is planarized by a CMP process, so that the second sacrificial layer 106 only fills the gap between the piezoelectric peripheral portion 1050 and the piezoelectric resonance layer 1051 , And the piezoelectric peripheral portion 1050, the piezoelectric resonance layer 1051, and the second sacrificial layer 106 constitute a flat upper surface. In other embodiments of the present invention, the second sacrificial layer 106 on the upper surface of the piezoelectric peripheral portion 1050 and the piezoelectric resonant layer 1051 can also be removed by an etch-back process, so that only the piezoelectric peripheral portion 1050 and the pressure are filled. In the gap between the electrical resonance layers 1051. Then, the second sacrificial layer 106 is patterned through a photolithography process or a photolithography combined etching process to form a first groove 107. The shape, size, and position of the first groove 107 determine the subsequently formed roof. The shape, size and position of the electrode recess. Preferably, the side wall of the first groove 107 is an inclined side wall inclined with respect to the plane where the piezoelectric resonance layer 1051 is located, and the angle between the side wall of the first groove 107 and the top surface of the piezoelectric resonance layer 1051 is 1, θ2 is all less than or equal to 45 degrees, thereby facilitating material coverage of the subsequent top electrode recess 1081, avoiding breakage, and improving thickness uniformity. Further preferably, the line width of the first groove 107 is the minimum line width allowed by the corresponding process, and the horizontal distance between the first groove 107 and the piezoelectric resonance layer 1051 is the minimum distance allowed by the corresponding process Therefore, while achieving a better transverse wave blocking effect, it is beneficial to reduce the size of the device. In other embodiments of the present invention, when the first groove 107 and the sacrificial protrusion 103' do not have an overlap in the vertical direction, after etching the second sacrificial layer 106, there may be a certain amount of over-etching, so that The bottom surface of the formed first groove 107 stops at the top surface of the first sacrificial layer 103 or in a certain thickness, so that the subsequently formed top electrode recess 1081 can make up for the bottom electrode recess 1041 not to the piezoelectric resonance layer 1051. The surrounding side portion is such that the combination of the top electrode recess 1081 and the bottom electrode recess 1041 can surround the piezoelectric resonance layer 1051 once. In other embodiments of the present invention, the cross-sectional shape of the first groove 107 can also be a spherical cap with a wide upper and a narrow bottom, that is, its longitudinal cross-section along the line XX' of FIG. 1A is U-shaped.

In other embodiments of the present invention, the second sacrificial layer 106 includes a first sub-sacrificial layer (not shown) and a second sub-sacrificial layer (not shown) stacked from bottom to top with different materials. The arrangement of the sub-sacrificial layer and the second sub-sacrificial layer enables precise control of the stop point of the etching during the subsequent etching to form the first groove, thereby accurately controlling the depth of the top electrode recess 1081 formed subsequently, thereby It can be seen that the thickness of the second sub-sacrificial layer determines the depth of the top electrode recess 1081 to be formed later. The following steps can be used to form the second sacrificial layer 106 having the first sub-sacrificial layer, the second sub-sacrificial layer and the first groove 107, including: firstly, filling the first sub-sacrificial layer in the place by vapor deposition or epitaxial growth process. In the gap between the piezoelectric resonance layer 1051 and the piezoelectric peripheral portion 1050, the material of the first sub-sacrificial layer can be converted into another material after being processed by some processes. In this embodiment, the first sub-sacrificial layer The layer can be a semiconductor material, and the gap is formed by a chemical vapor deposition process. At this time, the first sub-sacrificial layer not only fills the gap between the piezoelectric resonance layer 1051 and the piezoelectric peripheral portion 1050, but also covers the piezoelectric resonance Layer 1051 and the upper surface of the piezoelectric peripheral portion 1050; then, by a chemical mechanical planarization (CMP) process, the top of the first sub-sacrificial layer is planarized to the piezoelectric resonance layer 1051 and the piezoelectric peripheral portion 1050 The top surface is such that the first sub-sacrificial layer is only located in the gap between the piezoelectric resonance layer 1051 and the piezoelectric peripheral portion 1050; then, a suitable surface modification process is selected according to the material of the first sub-sacrificial layer, For example, it includes at least one of oxidation treatment, nitridation treatment and ion implantation, and surface modification treatment is performed on the top of the first sub-sacrificial layer to a certain thickness, so that this part of the first sub-sacrificial layer is transformed into another A second sub-sacrificial layer made of three kinds of materials, the second sub-sacrificial layer and the remaining first sub-sacrificial layer underneath that have not been surface-modified to fill the piezoelectric resonance layer 1051 and the piezoelectric peripheral portion The thickness of the second sacrificial layer 106 in the gap between 1050 and the second sacrificial layer depends on the depth of the top electrode recess 1081 that needs to be formed later; after that, the second sacrificial layer 106 may be filled due to the surface treatment process The top surface of the piezoelectric resonance layer 1051 is no longer flush with the top surface of the surrounding piezoelectric resonance layer 1051, which is not conducive to the subsequent deposition of the top electrode layer 108. Therefore, a chemical mechanical planarization (CMP) process is required to further remove the second sub-sacrificial layer The top surface is flattened to the top surface of the piezoelectric resonance layer 1051, so that the top surface of the second sacrificial layer 106 and the top surface of the surrounding piezoelectric resonance layer 1051 are level again to provide a relatively flat Operation surface. Then, the second sacrificial layer 106 corresponding to the second sub-sacrificial layer in the periphery of the effective working area of the bulk acoustic wave resonator to be fabricated (102A in FIG. 4H) can be etched by a combination of photolithography and etching. The etching can Stop on the top surface of the first sub-sacrificial layer, there may also be a certain amount of over-etching to stop in the first sub-sacrificial layer to form the first groove 107.

1A, 1B, and 4G, in step S5, first, a suitable method can be selected according to the material of the top electrode to be formed in the piezoelectric peripheral portion 1050, the piezoelectric resonance layer 1051, the second sacrificial layer 106, and The surface of the first groove 107 is covered with a top electrode material layer (not shown). For example, the top electrode material layer can be formed by magnetron sputtering, vapor deposition or other physical vapor deposition or chemical vapor deposition methods. The thickness of each position is uniform; then, a photoresist layer (not shown) defining a top electrode pattern is formed on the top electrode material layer by a photolithography process, and then the top electrode is etched using the photoresist layer as a mask The material layer to form the top electrode layer (ie, the patterned top electrode material layer or the remaining top electrode material layer) 108, after which the photoresist layer is removed. The top electrode material layer can use any suitable conductive material or semiconductor material well known in the art, wherein the conductive material can be a metal material with conductive properties, for example, Al, Cu, Pt, Au, Mo, W, Ir, One or more of Os, Re, Pd, Rh, and Ru, the semiconductor material is for example Si, Ge, SiGe, SiC, SiGeC, etc. In this embodiment, the top electrode layer 108 includes a top electrode resonator portion 1082 covering the piezoelectric resonant layer 1051, a top electrode recess portion 1081 covering the first groove 107, and a portion of the second electrode recess portion 1081 from the top electrode recess portion 1081. The top surface of the sacrificial layer 106 extends to the top electrode overlap portion 1080 on the piezoelectric peripheral portion 1050 outside the top electrode recess portion 1081 and the top electrode peripheral portion 1083 separated from the top electrode resonance portion 1082 and the top electrode recess portion 1081. The top electrode peripheral portion 1083 can be connected to the side of the top electrode overlap portion 1080 facing away from the top electrode resonance portion 1082 to serve as a metal contact of the bulk acoustic wave resonator to be formed in this area, or it can be connected to the top electrode overlap portion 1080 is separated to serve as a part of the top electrode overlap portion of adjacent bulk acoustic wave resonators. In other embodiments of the present invention, the top electrode peripheral portion 1083 may be omitted. The top electrode resonance portion 1082 may have the same or different shape as the piezoelectric resonance layer 1051 in plan view. The plan view shape is, for example, a pentagon, and its area is preferably larger than the piezoelectric resonance layer 1051 so that the piezoelectric resonance layer 1051 The top electrode resonant part 1082 and the bottom electrode resonant part 1042 are completely sandwiched between, which is beneficial to the reduction of the device size and the reduction of parasitic parameters. In other embodiments of the present invention, the shape of the top electrode resonant part 1082 can also be Polygons such as quadrilateral, hexagon, heptagon, or octagon. The top electrode layer 108 may be used as an input electrode or an output electrode that receives or provides electrical signals such as radio frequency (RF) signals. For example, when the bottom electrode layer 104 is used as an input electrode, the top electrode layer 108 can be used as an output electrode, and when the bottom electrode layer 104 is used as an output electrode, the top electrode layer 108 can be used as an input electrode, and the piezoelectric resonance layer 1051 The electrical signal input through the top electrode resonance portion 1082 or the bottom electrode resonance portion 1042 is converted into a bulk acoustic wave. For example, the piezoelectric resonance layer 1051 converts electrical signals into bulk acoustic waves through physical vibration. The top electrode recess 1081 is arranged along at least one side of the top electrode resonance part 1082 and connected to the corresponding side of the top electrode resonance part 1082, that is, the top electrode recess 1081 is along the top electrode resonance part 1082. The sides of 1082 are arranged at least in the area where the top electrode lap portion 1080 and the top electrode resonance portion 1082 are aligned. For example, the top electrode recess 1081 surrounds the top electrode resonance portion 1082 to form a closed loop structure (such as 2C and 2D, 2F), at this time, there is a gap H between the overlapping portion of the top electrode recess 1081 and the bottom electrode protrusion 1041 without contact, another example is the top electrode recess 1081 resonates at the top electrode A plurality of continuous edges of the portion 1082 extend to form an open loop structure (as shown in FIGS. 2A and 2B). The top electrode lap portion 1080 is electrically connected to the side of the top electrode recessed portion 1081 facing away from the top electrode resonance portion 1082, and passes through a portion of the top surface of the second sacrificial layer 106 from the top electrode recessed portion 1081 The part of the top surface of the protective layer 101 that extends to the outside of the second groove 102' is etched. The top electrode overlap portion 1080 and the bottom electrode overlap portion 1040 are staggered from each other (that is, the two are in the area of the cavity 102). No overlap), and the top electrode overlap portion 1080 and the bottom electrode overlap portion 1040 respectively expose at least one side of the second groove 102'. In an embodiment of the present invention, referring to FIGS. 2A and 2B, in a direction perpendicular to the bottom surface of the second groove 102', the top electrode recessed portion 1081 and the bottom electrode overlap portion 1040 The side facing the bottom electrode protrusion 1041 does not overlap, and the side of the bottom electrode protrusion 1041 and the top electrode lap portion 1080 facing the top electrode recess 1081 do not overlap. The projections of the top electrode overlap portion 1080 and the bottom electrode overlap portion 1040 on the bottom surface of the second groove 102' are just connected or separated from each other, and the top electrode overlap portion 1080 may only extend to A part of the periphery of one side of the second groove 102' is above the substrate.

Please refer to FIGS. 1A, 1B and 4H. In step S6, photolithography may be combined with an etching process or a laser cutting process to face the edge of the second groove 102' or the device of the bulk acoustic wave resonator at the piezoelectric peripheral portion 1050 Perforation is performed on the periphery of the area to form a release hole (not shown) capable of exposing a part of the sacrificial protrusion 103', a part of the first sacrificial layer 103, and a part of the second sacrificial layer 106 other than the sacrificial protrusion 103' ; Then, gas and/or liquid medicine are passed into the release hole to remove the second sacrificial layer 106 and the first sacrificial layer 103 with sacrificial protrusions 103', and then re-empty the second groove In order to form a cavity 102, the cavity 102 includes the space of the second groove 102' added by the bottom electrode protrusion 1041, the space restricted by the top electrode recess 1081, and the two sides under the top electrode recess 1081 that were originally second The space occupied by the sacrificial layer 106. Among them, the bottom electrode resonator 1042, the piezoelectric resonant layer 1051, and the top electrode resonator 1082 suspended above the cavity 102 and stacked in sequence form a monophonic sound film, and the bottom electrode resonator 1042, the piezoelectric resonant layer 1051, and the top electrode resonate The portion where the portion 1082 and the cavity 102 overlap each other in the vertical direction is the effective area, which is defined as the effective working area 102A. In the effective working area 102A, when electric energy such as a radio frequency signal is applied to the bottom electrode, the resonance portion 1042 and the top electrode resonate. Part 1082 will cause vibration and resonance in the thickness direction (ie longitudinal direction) of the piezoelectric resonance layer 1051 due to the piezoelectric phenomenon generated in the piezoelectric resonance layer 1051. The other region of the cavity 102 is the invalid region 102B. In the ineffective region 102B, a region that does not resonate due to a piezoelectric phenomenon even when electric energy is applied to the top electrode layer 108 and the bottom electrode layer 104. The monophonic sound film composed of the bottom electrode resonance part 1042, the piezoelectric resonance layer 1051 and the top electrode resonance part 1082 suspended above the effective working area 102A and stacked in sequence can output resonance corresponding to the vibration of the piezoelectric phenomenon of the piezoelectric resonance layer 1051 Frequency radio frequency signal. Specifically, when electric energy is applied to the top electrode resonance portion 1082 and the bottom electrode resonance portion 1042, a bulk acoustic wave is generated by a piezoelectric phenomenon generated in the piezoelectric resonance layer 1051. In this case, in addition to the desired longitudinal wave from the generated bulk acoustic wave, there are also parasitic transverse waves, which will be blocked at the top electrode recess 1081 and the bottom electrode protrusion 1041, limiting the transverse wave in the effective working area 102A , Prevent it from propagating to the film layer on the periphery of the cavity, thereby improving the acoustic loss caused by the transverse wave propagating into the film layer on the periphery of the cavity, thereby improving the quality factor of the resonator, and finally improving the device performance.

It should be noted that step S6 can be performed after all the film layers above the cavity 102 to be formed are completed. Therefore, the first sacrificial layer 103 and the second sacrificial layer 106 can continue to be used to protect the cavity 102. The space and the film structure of the bottom electrode layer 104 to the top electrode layer 108 formed thereon are stacked to avoid the risk of cavity collapse when the subsequent process is continued after the cavity 102 is formed. In addition, the release hole formed in step S6 may be kept first, so that the release hole can be sealed by a subsequent packaging process such as two-substrate bonding, so that the cavity 102 is closed.

It should be noted that in step S1 of the method for manufacturing a bulk acoustic wave resonator of the foregoing embodiments, the first sacrificial layer is formed by etching the substrate to form the second groove 102' and filling the second groove 102'. On a part of the substrate, so that the cavity 102 formed in step S6 is a groove structure with the entire bottom recessed in the substrate. However, the technical solution of the present invention is not limited to this. In other embodiments of the present invention, In step S1 of the example, the first sacrificial layer 103 protruding on the substrate as a whole can be formed by film deposition combined with photolithography and etching processes, so that the cavity formed in step S6 is protruding as a whole. For the cavity structure on the surface of the substrate, specifically, please refer to FIG. 2E and FIG. 5. In step S1, a groove 102' for making a cavity is no longer formed in the provided substrate, but The first sacrificial layer 103 is covered on the etching protection layer 101 on the surface of the substrate 100; then the first sacrificial layer 103 is patterned by a photolithography and etching process, leaving only the first sacrificial layer covering the area 102 103, and then the first sacrificial layer 103 is on a part of the substrate. The first sacrificial layer 103 can have a narrow top and a wide bottom structure. The thickness of the first sacrificial layer 103 determines the depth of the cavity 102 to be subsequently formed. A sacrificial layer 103 and a substrate are covered with a sacrificial material layer for making the sacrificial protrusions 103', and then the sacrificial protrusions 103' are formed on a part of the first sacrificial layer 103 through a process of photolithography and etching. In this embodiment, the subsequent steps are exactly the same as the corresponding parts in the method of manufacturing the bulk acoustic wave resonator of the embodiment shown in FIGS. 4A to 4H, and will not be repeated here, except that the bottom electrode peripheral portion 1043 and the bottom electrode are formed. The corresponding sidewalls of the electrode overlap portion 1040, the piezoelectric peripheral portion 1050, the top electrode peripheral portion 1083, and the top electrode overlap portion 1080 need to be deformed to adapt to the protruding first sacrificial layer 103, and the longitudinal cross-sections all become "Z" shapes. structure.

The bulk acoustic wave resonator of the present invention preferably adopts the manufacturing method of the bulk acoustic wave resonator of the present invention, so that the bottom electrode overlap portion, the bottom electrode protrusion portion and the bottom electrode resonance portion are manufactured together, and the top electrode overlap portion, the top electrode The electrode recessed part and the top electrode resonance part are manufactured together, thereby simplifying the process and reducing the manufacturing cost.

Obviously, those skilled in the art can make various changes and modifications to the invention without departing from the spirit and scope of the invention. In this way, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

A bulk acoustic wave resonator, characterized in that it comprises:

Substrate

The bottom electrode layer is disposed on the substrate, and a cavity is formed between the bottom electrode layer and the substrate, the bottom electrode layer has a bottom electrode protrusion, and the bottom electrode protrusion is located The area of the cavity is convex in a direction away from the bottom surface of the cavity;

A piezoelectric resonance layer formed on the bottom electrode layer above the cavity;

A top electrode layer formed on the piezoelectric resonance layer, the top electrode layer having a top electrode recessed portion, the top electrode recessed portion is located in a region of the cavity and toward a direction close to the bottom surface of the cavity The top electrode concave portion and the bottom electrode convex portion are both located in the cavity area on the periphery of the piezoelectric resonance layer, and the bottom electrode convex portion and the top electrode concave portion both surround the pressure The electric resonance layer extends in the peripheral direction, and the two are at least partially opposite to each other.
The bulk acoustic wave resonator according to claim 1, wherein the bottom electrode layer further comprises a bottom electrode overlap portion, one end of the bottom electrode overlap portion is connected to the bottom electrode protrusion, and the other end is overlapped To the substrate on the periphery of the cavity; the top electrode layer further includes a top electrode lap portion, one end of the top electrode lap portion is connected to the top electrode recess, and the other end extends to the periphery of the cavity Above the substrate; the bottom electrode overlap portion and the top electrode overlap portion are staggered.
The bulk acoustic wave resonator according to claim 2, wherein the bottom electrode layer further comprises a bottom electrode resonant part overlapping the piezoelectric resonance layer, and the top electrode layer further comprises The top electrode resonant part of the overlapping layer, the bottom electrode resonant part and the top electrode resonant part are both polygonal.
The bulk acoustic wave resonator according to claim 3, wherein the bottom electrode protruding portion is provided along the side of the bottom electrode resonant portion and is provided at least on the bottom electrode overlap portion and the bottom electrode In the area where the resonance parts are aligned, the top electrode recessed part is arranged along the side of the top electrode resonance part and is at least arranged in the area where the top electrode overlap part and the top electrode resonance part are aligned.
The bulk acoustic wave resonator according to claim 4, wherein the protrusion of the bottom electrode is at least offset from the overlap portion of the top electrode above the cavity, or the protrusion of the bottom electrode Encircle the bottom electrode resonance part; the top electrode recessed part is at least offset from the bottom electrode overlapping part above the cavity, or the top electrode recess part encircles the top electrode resonance part one round.
The bulk acoustic wave resonator according to claim 5, wherein the projections of the top electrode concave portion and the bottom electrode convex portion on the bottom surface of the cavity just meet or are staggered or overlapped.
The bulk acoustic wave resonator according to claim 3, wherein the bottom electrode protruding portion, the bottom electrode overlapping portion, and the bottom electrode resonant portion are formed of the same film layer, and the top electrode recessed portion , The top electrode overlapping part and the top electrode resonance part are formed by the same film layer.
The bulk acoustic wave resonator according to claim 4, wherein the bottom electrode overlap portion completely covers the cavity above the cavity part where it is located, and in the width direction of the top electrode overlap portion, There is no overlap with the overlapping part of the top electrode.
The bulk acoustic wave resonator according to any one of claims 1 to 8, wherein the horizontal distance between the bottom electrode protrusion and the piezoelectric resonance layer is such that the bottom electrode protrusion is manufactured. The minimum distance allowed by the process; the horizontal distance between the top electrode recess and the piezoelectric resonance layer is the minimum distance allowed by the process of manufacturing the top electrode recess.
The bulk acoustic wave resonator according to any one of claims 1 to 8, wherein the side wall of the top electrode recessed portion is inclined relative to the top surface of the piezoelectric resonance layer, and the bottom electrode protruding portion The sidewalls of the piezoelectric resonance layer are inclined relative to the bottom surface of the piezoelectric resonance layer.
The bulk acoustic wave resonator according to claim 10, wherein the angle between the sidewall of the top electrode recess and the top surface of the piezoelectric resonance layer is less than or equal to 45 degrees, and the bottom electrode is convex The angle between the side wall of the raised portion and the bottom surface of the piezoelectric resonance layer is less than or equal to 45 degrees.
The bulk acoustic wave resonator according to any one of claims 1 to 8 or 11, wherein the line width of the bottom electrode protrusion is the smallest line allowed by the process of manufacturing the bottom electrode protrusion. Width; the line width of the top electrode recess is the smallest line width allowed by the process of manufacturing the top electrode recess.
The bulk acoustic wave resonator according to any one of claims 1 to 8 or 11, wherein the cavity is a groove structure with an entire bottom recessed in the substrate, or a groove structure with an entire bottom protruding from the substrate. The cavity structure on the surface of the substrate.
A filter, characterized by comprising at least one bulk acoustic wave resonator according to any one of claims 1 to 13.
A radio frequency communication system, characterized by comprising at least one filter according to claim 14.
A method for manufacturing a bulk acoustic wave resonator, characterized in that it comprises:

Providing a substrate, forming a first sacrificial layer with sacrificial protrusions on part of the substrate;

Forming a bottom electrode layer on the first sacrificial layer, and a portion of the bottom electrode layer covering the surface of the sacrificial protrusion forms a bottom electrode protrusion;

Forming a piezoelectric resonance layer on the bottom electrode layer, the piezoelectric resonance layer exposing the bottom electrode protrusions;

Forming a second sacrificial layer with a first groove in the exposed area around the piezoelectric resonance layer;

Forming a top electrode layer on the piezoelectric resonant layer and a part of the second sacrificial layer around the piezoelectric resonant layer, the portion of the top electrode layer covering the first groove forms a top electrode recess;

The second sacrificial layer and the first sacrificial layer with sacrificial protrusions are removed, the positions of the second sacrificial layer and the first sacrificial layer with sacrificial protrusions form a cavity, and the top electrode recess And the bottom electrode protruding portion are both located in a cavity area on the periphery of the piezoelectric resonance layer, and the bottom electrode protruding portion and the top electrode recessed portion both extend around the peripheral direction of the piezoelectric resonance layer, And the two are at least partially opposite.
The method for manufacturing a bulk acoustic wave resonator according to claim 16, wherein the step of forming a first sacrificial layer with sacrificial protrusions on a part of the substrate comprises: etching the substrate to form grooves in the substrate In the substrate; a first sacrificial layer is formed to fill the groove; a sacrificial material layer is covered on the first sacrificial layer and the substrate, and the sacrificial material layer is patterned to form a sacrificial protrusion Protruding on part of the first sacrificial layer; or

The step of forming a first sacrificial layer with sacrificial protrusions on a part of the substrate includes: covering the first sacrificial layer on the substrate; patterning the first sacrificial layer to form the first sacrificial layer protruding on the part On the substrate; covering a sacrificial material layer on the first sacrificial layer and the substrate, and patterning the sacrificial material layer to form sacrificial protrusions protruding on part of the first sacrificial layer.
17. The method for manufacturing a bulk acoustic wave resonator according to claim 16, wherein the step of removing the second sacrificial layer and the first sacrificial layer with sacrificial protrusions comprises:

After the top electrode layer is formed, at least one release hole is formed, and the release hole exposes at least part of the second sacrificial layer, part of the sacrificial protrusion, or part of the first sacrificial layer other than the sacrificial protrusion;

Gas and/or liquid medicine are passed into the release hole to remove the second sacrificial layer and the first sacrificial layer with the sacrificial protrusions.
The method for manufacturing a bulk acoustic wave resonator according to any one of claims 16 to 18, wherein the step of forming the bottom electrode layer comprises: depositing a bottom electrode material layer to cover all the sacrificial protrusions. The first sacrificial layer; the bottom electrode material layer is patterned to form a bottom electrode overlap portion, the bottom electrode protrusion portion, and the bottom electrode resonant portion that are sequentially connected, the bottom electrode resonant portion and the pressure The electric resonance layer overlaps, and one end of the bottom electrode lap portion facing away from the bottom electrode protrusion portion is lapped onto the substrate on the periphery of the cavity.
The method of manufacturing a bulk acoustic wave resonator according to claim 19, wherein the step of forming the top electrode layer comprises: depositing a top electrode material layer to cover the second sacrificial layer having the first groove and On the piezoelectric resonance layer; the top electrode material layer is patterned to form a top electrode lap portion, the top electrode recessed portion, and a top electrode resonant portion that are sequentially connected, the top electrode resonant portion and the piezoelectric resonant The layers overlap, the end of the top electrode lap portion facing away from the top electrode recessed portion extends above the substrate at the periphery of the cavity, and the top electrode lap portion and the bottom electrode lap portion are staggered from each other .
The method of manufacturing a bulk acoustic wave resonator according to claim 20, wherein the bottom electrode resonator portion and the top electrode resonator portion are both polygonal, and the bottom electrode protruding portion resonates along the bottom electrode The side of the part is arranged at least in the area where the bottom electrode overlapping part and the bottom electrode resonance part are aligned, and the top electrode recess is arranged along the edge of the top electrode resonance part and is at least arranged in the In the area where the top electrode overlap portion and the top electrode resonance portion are aligned.
The method of manufacturing a bulk acoustic wave resonator according to any one of claims 16 to 18 and 20 to 21, wherein the horizontal distance between the bottom electrode protrusion and the piezoelectric resonance layer is The minimum distance allowed by the process of the bottom electrode protrusion; the horizontal distance between the top electrode recess and the piezoelectric resonance layer is the minimum distance allowed by the process of manufacturing the top electrode recess.
The method for manufacturing a bulk acoustic wave resonator according to any one of claims 16 to 18 and 20 to 21, wherein the line width of the bottom electrode protrusion is a process of manufacturing the bottom electrode protrusion The minimum line width allowed; the line width of the top electrode recess is the minimum line width allowed by the process of manufacturing the top electrode recess.