WO2020199506A1

WO2020199506A1 - Bulk acoustic wave resonator and manufacturing method therefor, filter and radio-frequency communication system

Info

Publication number: WO2020199506A1
Application number: PCT/CN2019/105089
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: JP7199758B2; JP2022507320A; CN111786648A

Abstract

A bulk acoustic wave resonator and a manufacturing method therefor, a filter and a radio-frequency communication system. A top electrode protrusion portion that is formed on the periphery of a piezoelectric resonance layer (1051) and is 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 both are 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

A bottom electrode layer is disposed on the substrate, and a cavity is formed between the bottom electrode layer and the substrate, and a portion of the bottom electrode layer above the cavity is flat and extended;

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

The top electrode layer is formed on the piezoelectric resonance layer, the top electrode layer has a top electrode protrusion, and the top electrode protrusion is located in the region of the cavity on the periphery of the piezoelectric resonance layer and Protruding in a direction away from the bottom surface of the cavity, and the top electrode protruding portion extends around the peripheral direction of the piezoelectric resonance layer.

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 a flat top surface on part of the substrate;

Forming a bottom electrode layer on a part of the first sacrificial layer, and the part of the bottom electrode layer on the top surface of the first sacrificial layer extends flat;

Forming a piezoelectric resonance layer on the bottom electrode layer, the piezoelectric resonance layer exposing part of the first sacrificial layer and part of the bottom electrode layer;

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

Forming a top electrode layer on the piezoelectric resonance layer and a part of the second sacrificial layer around the piezoelectric resonance layer, and the part of the top electrode layer covering the sacrificial protrusion forms a top electrode protrusion;

The second sacrificial layer having the sacrificial protrusions and the first sacrificial layer are removed, a cavity is formed at the positions of the second sacrificial layer having the sacrificial protrusions and the first sacrificial layer, and the top electrode protrusions The portion is located in a cavity area on the periphery of the piezoelectric resonance layer and extends around the peripheral direction of the piezoelectric resonance layer.

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 protrusion of the top electrode on the cavity surrounding the piezoelectric resonant layer and be reflected back to the area corresponding to the piezoelectric resonant layer, thereby reducing and reducing the propagation of the transverse wave to the periphery of the cavity. The loss caused by the time in the film layer, thereby improving the acoustic wave loss, so that the quality factor of the resonator is improved, and finally the performance of the device 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, the bottom electrode layer and the top electrode layer will not fully cover the cavity), thereby reducing the circumference of the cavity The effect of the film layer on the longitudinal vibration generated by the piezoelectric resonance layer improves performance.

3. Even if the top electrode protrusion and the bottom electrode layer overlap each other, the overlapped part is still a gap structure, which can greatly reduce the parasitic parameters and avoid the top electrode layer and the bottom electrode layer in the cavity area. Problems such as electrical contact 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 protruding part of the top electrode surrounds the resonance part of the top electrode, which can block transverse waves in all directions from the periphery of the piezoelectric resonance layer, thereby obtaining a better quality factor.

7. 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 protrusion, the top electrode resonance part and the top electrode overlap part are formed by the same film layer, and the film thickness is uniform. As a result, the process can be simplified and the cost can be reduced, and because the film thickness of the top electrode protrusion is basically the same as other parts of the top electrode layer, the top electrode protrusion will not be broken, and the reliability of the device can be improved.

8. The bottom electrode layer is flat in the cavity area. On the one hand, it can help improve the thickness uniformity of the film in the effective area. On the other hand, it can help reduce the difficulty of the etching process when forming the piezoelectric resonance layer, and avoid The top surface of the bottom electrode layer is not flat, causing the problem of piezoelectric material etching residue, thereby reducing parasitic parameters.

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

2D is a schematic cross-sectional structure diagram of a bulk acoustic wave resonator according to another embodiment of the 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 4F 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'-groove; 102A-effective working area; 102B-ineffective area; 103-first sacrificial layer; 104-bottom electrode layer (that is, the remaining bottom Electrode material layer); 1040-bottom electrode overlap portion; 1041-bottom electrode resonant portion; 1042-bottom electrode peripheral portion; 105-piezoelectric material layer; 1050-piezoelectric peripheral portion; 1051-piezoelectric resonance layer (or called Is the piezoelectric resonance part); 106-second sacrificial layer; 107-sacrificial protrusion; 108-top electrode layer (that is, the remaining top electrode material layer); 1080-top electrode overlap portion; 1081-top electrode protrusion portion ; 1082-top electrode resonance part; 1083-top electrode peripheral part.

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. 2D. 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 overlap portion 1040 and a bottom electrode resonant portion 1041 that are connected in sequence. The portion of the bottom electrode layer 104 above the cavity 102 extends flat, that is, the bottom electrode overlap portion 1040 is located above the cavity. The top surface of the part is flush with the top surface of the bottom electrode resonant portion 1041, and the bottom surface of the portion of the bottom electrode overlapping portion 1040 above the cavity is flush with the bottom surface of the bottom electrode resonant portion 1041. The top electrode layer 108 includes a top electrode lap portion 1080, a top electrode protrusion portion 1081, and a top electrode resonance portion 1082 that are sequentially connected. The bottom electrode resonance portion 1041, the top electrode resonance portion 1082 and the piezoelectric resonance layer 1051 overlap each other, and The cavity 102 and the overlapping bottom electrode resonance portion 1041, the piezoelectric resonance layer 1051, and the area corresponding to the top electrode resonance portion 1082 constitute the effective working area 102A of the bulk acoustic wave resonator, and the cavity 102 except the effective working area 102A The other part is the invalid area 102B. The piezoelectric resonance layer 1051 is located in the effective working area 102A and separated from the film around the cavity 102, which can completely confine the effective working area of the bulk acoustic wave resonator to the cavity 102 area. And it can reduce the influence of the film layer around the cavity on the longitudinal vibration generated by the piezoelectric resonant layer, reduce the parasitic parameters generated in the invalid region 102B, and improve the performance of the device. The bottom electrode resonant portion 1041, the piezoelectric resonant layer 1051, and the top electrode resonant portion 1082 are all flat structures with flat upper and lower surfaces. The top electrode protruding portion 1081 is located above the cavity 102B outside the effective working area 102A and is electrically connected The top electrode resonant part 1082 is connected, and is convex toward the direction away from the bottom surface of the cavity 102. The top electrode protruding portion 1081 protrudes upward relative to the top surface of the top electrode resonance portion 1082 as a whole and is located in the cavity area (ie 102B) outside the piezoelectric resonance layer 1051. The top electrode protrusion 1081 may be a solid structure or a hollow structure, preferably a hollow structure, so that the film thickness of the top electrode layer 108 can be made uniform, and the solid top electrode protrusion 1081 can prevent the top electrode resonance portion 1082 from being caused. The piezoelectric resonant layer 1051 and the bottom electrode resonant portion 1041 underneath are deformed, thereby further improving the resonance factor. Wherein, the bottom electrode resonant portion 1041, the top electrode resonant portion 1082 are all polygons (the top surface and the bottom surface are both polygonal), and the bottom electrode resonant portion 1041, the top electrode resonant portion 1082 may have similar shapes (As shown in Figures 2A and 2C) or exactly the same (as shown in Figures 1A and 2B). The piezoelectric resonance layer 1051 has a polygonal structure similar to the shape of the bottom electrode resonance portion 1041 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 1041 is aligned, and one corner of the top electrode overlapping part 1080 and the top electrode resonant part 1082 are aligned. The bottom electrode overlapping part 1040 and the top electrode overlapping part 1080 are equivalent to two straps of a "watch". The top electrode convex portion 1081 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 top electrode convex portion 1081 is equivalent to the connection structure between the dial of a "watch" and a strap. The bottom electrode resonant part 1041, the piezoelectric resonant layer 1051, and the top electrode resonant part 1082 stack structure in the effective area 102A are equivalent to the dial of a watch. Except for the part of the strap that is connected to the film layer on the substrate surrounding the cavity, the remaining parts are separated from the film layer on the substrate surrounding the cavity through the cavity. That is, in this embodiment, the top electrode protrusion 1081 extends around the peripheral direction of the piezoelectric resonance layer 1051, and the top electrode protrusion 1081 only surrounds the piezoelectric resonance layer 1051 in the peripheral direction of the piezoelectric resonance layer 1051. With reference to the plane where the piezoelectric resonant layer 1051 is located, the top electrode protrusion 1081 and the bottom electrode overlap portion 1040 are located on both sides of the piezoelectric resonant layer 1051 and face each other. A certain transverse wave blocking effect can help reduce the area of the invalid region 102B that is not covered by the top electrode overlap portion 1080 and the bottom electrode overlap portion 1040, which in turn is beneficial to the reduction of the device size and at the same time. The area of the top electrode overlap portion 1080 and the bottom electrode overlap portion 1040 is small to further reduce parasitic parameters and improve the electrical performance of the device. The bottom electrode lap portion 1040 is electrically connected to one side of the bottom electrode resonant portion 1041, and extends from the bottom electrode resonant portion 1041 through a cavity (ie 102B) outside the bottom electrode resonant portion 1041. To the upper part of the etching protection layer 101 on the periphery of the cavity 102; the top electrode lap portion 1080 is electrically connected to the side of the top electrode convex portion 1081 facing away from the top electrode resonance portion 1082, and from The top electrode protruding portion 1081 is suspended above the cavity (ie 102B) outside the top electrode protruding portion 1081 and then extends to above the partial etching protection layer 101 on the periphery of the cavity 102; The electrode overlap portion 1040 and the top electrode overlap portion 1080 extend above the substrate outside the two opposite sides of the cavity 102, at this time, the bottom electrode overlap portion 1040 and the top electrode overlap portion 1080 are staggered in the cavity 102 area (that is, the two do not overlap), thus, the parasitic parameters can be reduced, and the leakage, short circuit and other problems caused by the contact between the bottom electrode overlap portion and the top electrode overlap portion can be avoided. 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 1041, and the top electrode lap portion 1080 can be used to connect a corresponding signal line to pass the top electrode The raised portion 1081 transmits the corresponding signal to the top electrode resonance portion 1082, so that the bulk acoustic wave resonator can work normally. Specifically, the bottom electrode overlap portion 1040 and the top electrode overlap portion 1080 are respectively connected to the bottom electrode resonance portion 1041 and The top electrode resonance part 1082 applies a time-varying voltage to excite the longitudinal extension mode or "piston" mode. The piezoelectric resonance layer 1051 converts the energy in the form of electric energy into longitudinal waves. In this process, parasitic transverse waves are generated. The top electrode protrusion 1081 These transverse waves can be blocked from propagating into the film layer surrounding the cavity and confined within the cavity 102, thereby avoiding the energy loss caused by the transverse waves and improving the quality factor.

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

In addition, the side wall of the top electrode protrusion 1081 is an inclined side wall relative to the top surface of the piezoelectric resonance layer, as shown in FIG. 1B, the top electrode protrusion 1081 is along the line XX' in FIG. 1A. The cross-section is trapezoidal or trapezoidal-like, and the clamps α1 and α2 between the two side walls of the top electrode protrusion 1081 and the top surface of the piezoelectric resonance layer 1051 are all less than or equal to 45 degrees, thereby avoiding the risk of topping The sidewalls of the electrode protrusion 1081 are too vertical to cause the top electrode protrusion 1081 to break, thereby affecting the effect of signal transmission to the top electrode resonance portion 1082, and at the same time, the thickness uniformity of the entire top electrode layer 108 can be improved.

In a preferred embodiment of the present invention, the bottom electrode resonant portion 1041 and the bottom electrode overlap portion 1040 are formed by the same film layer manufacturing process (that is, the same film layer manufacturing process), and the top electrode resonant portion 1081 and the top electrode protrusion The portion 1081 and the top electrode overlap portion 1080 are formed by the same film layer manufacturing process (that is, the same film layer manufacturing process), that is, the bottom electrode resonance portion 1041 and the bottom electrode overlap portion 1040 are integrated film layers, and the top electrode The resonant part 1082, the top electrode convex part 1081 and the top electrode lap part 1080 are made in one piece, which can simplify the process and reduce the cost. Among them, it is used to make the bottom electrode resonance part 1041 and the bottom electrode lap part. The film material of 1040 and the film material used to make the top electrode resonator portion 1082, the top electrode protrusion portion 1081 and the top electrode lap portion 1080 can use any suitable conductive material or semiconductor material that is well known in the art, respectively, Wherein, the conductive material may be a metal material with conductive properties, for example, aluminum (Al), copper (Cu), platinum (Pt), gold (Au), molybdenum (Mo), tungsten (W), iridium (Ir), One or more of 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 resonant portion 1041 and the bottom electrode overlapping portion 1040 can also be formed by different film layer production processes, provided that the process cost and process technology allow, the top electrode resonant portion 1082, the top electrode The electrode protruding portion 1081 and the top electrode lap portion 1080 can be formed using different film production processes.

2A to 2C, in order to further improve the transverse wave blocking effect, the top electrode protruding portion 1081 extends to more continuous sides of the top electrode resonance portion 1082. For example, referring to FIG. 2A, the piezoelectric resonance layer 1051, the top electrode resonance portion 1082, and the bottom electrode resonance portion 1041 are all pentagonal planar structures, and the area of the piezoelectric resonance layer 1051 is the smallest, followed by the top electrode resonance portion 1082 , The area of the bottom electrode resonance portion 1041 is the largest, the top electrode protrusions 1081 are arranged along multiple sides of the top electrode resonance portion 1082 and connected to these sides, and the top electrode protrusions 1081 are on the bottom surface of the cavity 102 The projection of the exposed portion of the bottom electrode resonance portion 1041 and the bottom electrode overlapping portion 1040 is connected to the projection on the bottom surface of the cavity 102, so that the top electrode protrusion 1081 and the bottom electrode overlapping portion 1040 do not overlap , Which can reduce parasitic parameters. For another example, referring to FIG. 2B, the piezoelectric resonance layer 1051, the top electrode resonance portion 1082, and the bottom electrode resonance portion 1041 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 1041 are the same or substantially the same, the top electrode protrusion 1081 surrounds the top electrode resonance portion 1082, and the projection of the top electrode resonance portion 1082 and the bottom electrode resonance portion 1041 on the bottom surface of the cavity 102 Due to the overlap, the transverse wave generated by the piezoelectric resonance layer 1051 can be blocked in all directions by the closed annular DE top electrode protrusion 1081.

2A to 2C, 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 corner of the bottom electrode resonant portion 1041, and from the bottom electrode resonant portion The corresponding side of 1041 is suspended above the cavity (ie 102B) outside the bottom electrode resonant part 1041 and then extends to above the part of the etching protection layer 101 on the periphery of the cavity 102; the top electrode overlap portion 1080 is electrically connected to at least one side or at least one corner of the top electrode convex portion 1081 facing away from the top electrode resonant portion 1082, and is suspended from the top electrode convex portion 1081 on the top electrode convex portion The cavity on the outside of 1081 (ie 102B) extends above the part of the etching protection layer 101 on the periphery of the cavity 102, and the top electrode overlap portion 1080 and the bottom electrode overlap portion 1040 are in the cavity. The projections on the bottom surface of the cavity 102 may be directly connected or separated from each other. Therefore, the top electrode overlap portion 1080 and the bottom electrode overlap portion 1040 do not overlap in the cavity 102 area and are mutually staggered. For example, as shown in FIGS. 1A and 2A to 2B, the bottom electrode overlap portion 1040 may only extend above a part of the substrate at the periphery of 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. 2C, the bottom electrode overlap portion 1040 is provided along all sides of the bottom electrode resonant portion 1041 and extends continuously to the substrate on the periphery of the cavity 102, thereby making the bottom electrode The overlap portion 1040 can extend above a part of the substrate in more directions on the periphery of the cavity 102, that is, at this time, the bottom electrode overlap portion 1040 completely covers the cavity above the portion of the cavity where it is located. 102, so that the laying of a large-area bottom electrode overlap portion 1040 can enhance the supporting force of the film 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 has no overlap, thereby avoiding that the arrangement of the large-area top electrode overlap portion 1080 overlaps with the bottom electrode overlap portion 1040 and other structures in the vertical direction to introduce excessive parasitic parameters, which can further improve the device performance Electrical performance 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 1041 connected to the bottom electrode lap portion 1040 and the top electrode resonant portion 1082 connected to the top electrode protrusion 1081 is completely suspended, which can help reduce the area of the ineffective region 102B. In turn, parasitic parameters such as parasitic capacitance generated in the invalid region 102B are reduced, and device performance is improved. Preferably, the top electrode protruding portion 1081 above the cavity 102 is at least staggered with the bottom electrode overlapping portion 1040 (that is, the two do not overlap in the cavity area), thereby further reducing the ineffective region 102B. Parasitic parameters such as generated parasitic capacitance can improve 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 protrusion 1081 is to the effective working area 102A, the better, and the smaller the line width of the top electrode protrusion 1081, the better Preferably, the line width of the top electrode protrusion 1081 is the minimum line width allowed by the corresponding process, and the horizontal distance between the top electrode protrusion 1081 and the effective working area 102A (ie, the piezoelectric resonance layer 1051) corresponds to The minimum distance allowed by the process.

It is worth noting that in the above embodiments, the top electrode resonance portion 1082 and the bottom electrode resonance portion 1041 have the same shape or the same area, or the area of the bottom electrode resonance portion 1041 is larger than that 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 1041 may not be similar, but preferably, the shape of the top electrode protrusion 1081 is the most It is preferably adapted to the shape of the piezoelectric resonance layer 1051, which 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 2C) of the present invention, including:

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

S2, forming a bottom electrode layer on a part of the first sacrificial layer, and the part of the bottom electrode layer on the top surface of the first sacrificial layer extends flat;

S3, forming a piezoelectric resonance layer on the bottom electrode layer, the piezoelectric resonance layer exposing part of the first sacrificial layer and part of the bottom electrode layer;

S4, forming a second sacrificial layer with sacrificial protrusions 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 portion of the top electrode layer covering the sacrificial protrusion forms a top electrode protrusion;

S6, removing the second sacrificial layer having the sacrificial protrusions and the first sacrificial layer, forming a cavity at the positions of the second sacrificial layer having the sacrificial protrusions and the first sacrificial layer, and the top electrode The protruding portion is located in the cavity area on the periphery of the piezoelectric resonance layer and extends around the peripheral direction of the piezoelectric resonance layer.

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 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 groove 102' depend on the depth and shape of the cavity required for the bulk acoustic wave resonator to be manufactured. The cross-sectional shape of the groove 102' is rectangular. In other embodiments of the present invention, the groove 102 The cross-section of 'can also be any other suitable shape, such as a circle, an ellipse, or other polygons other than a rectangle (such as a pentagon, a hexagon, etc.).

Then, referring to FIGS. 1A, 1B, and 4B, the first sacrificial layer 103 can be filled in the groove 102' by vapor deposition, thermal oxidation, spin coating, or epitaxial growth. The first sacrificial layer 103 can Choose 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 may be Ge, and the first sacrificial layer formed at this time 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 first sacrifice The top of the layer 103 is flattened to the top surface of the etching protection layer 101, so that the first sacrificial layer 103 is only located in the groove 102', and the top surface of the first sacrificial layer 103 and the surrounding etching The top surface of the etch protection layer 101 is flush, thereby providing a flat process surface for subsequent formation of the bottom electrode layer 104 having a flat surface.

1A, 1B and 4C, in step S2, first, a suitable method can be selected according to the material of the bottom electrode to be formed to cover the surface of the etching protection layer 101 and the first sacrificial layer 103 with a bottom electrode material layer ( (Not shown), for example, the bottom electrode material layer can be formed by physical vapor deposition or chemical vapor deposition methods such as magnetron sputtering, evaporation, etc.; then, a photolithography process is used to form a bottom electrode pattern on the bottom electrode material layer. The photoresist layer (not shown) 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, and then the photoresist Layer removal. 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 (remaining bottom electrode material layer) 104 includes a bottom electrode resonant portion 1041 covering the effective working area 102A formed subsequently, through the first sacrificial layer 103 from one side of the bottom electrode resonant portion 1041. The bottom electrode lap portion 1040 on the part of the etching protection layer 101 and the bottom electrode peripheral portion 1042 separated from the bottom electrode resonance portion 1041 extending to the outside of the groove 102', the bottom electrode peripheral portion 1042 may overlap the bottom electrode The connecting portion 1040 is connected to the side of the bottom electrode resonance portion 1041 to be used as a metal contact of the bulk acoustic wave resonator to be formed in this area, or it can be separated from the bottom electrode overlapping portion 1040 as an adjacent bulk acoustic wave resonance In other embodiments of the present invention, a part of the overlapping portion of the bottom electrode of the detector, the peripheral portion 1042 of the bottom electrode may be omitted. The top-view shape of the bottom electrode resonant portion 1041 may be a pentagon, and in other embodiments of the present invention, it may also be a quadrilateral or a hexagon. The bottom electrode lap portion 1040 is electrically connected to at least the bottom electrode resonant portion 1041 One side or at least one corner, and from the corresponding side of the bottom electrode resonant portion 1041 through the top surface of the first sacrificial layer 103 outside the bottom electrode resonant portion 1041 to extend to the part of the periphery of the groove 102' The top surface of the protective layer 101. In addition, since the top surface of the first sacrificial layer 103 and the top surface of the etching protection layer 101 in this embodiment are flush, the bottom surface and the top surface of the bottom electrode layer 104 formed can be flush. At this time, the bottom electrode layer 104 extends flat in the global scope, that is, the bottom electrode resonance portion 1041 and the bottom electrode overlap portion 1040 have a flush bottom surface and a flush top surface. Preferably, as shown in FIG. 2C, 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 joint portion 1080 has no overlap, so as to improve the supporting force for the subsequent film layer, and try to avoid the introduction of unnecessary parasitic parameters by overlapping with the top electrode lap portion 1080. The bottom electrode resonance part 1041 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.

1A, 1B and 4C, in step S3, firstly, 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 resonant layer 1051 and a piezoelectric peripheral portion 1050 that are separated from each other. The piezoelectric resonant layer 1051 is located on the bottom electrode resonant portion 1041, exposing the bottom electrode lap portion 1040, and can The bottom electrode resonance portion 1041 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 1041, 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 a portion of the first sacrificial layer 103 above the bottom electrode overlapping portion 1040 and around the bottom electrode resonance portion 1041, and further pass through the formed gap To limit the formation area of the subsequent second sacrificial layer, and at the same time provide a relatively flat process surface for the subsequent formation of sacrificial bumps, 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 1042. 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 4D, 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.; then, The top of the second sacrificial layer 106 is planarized by a CMP process, so that the second sacrificial layer 106 is only filled in the gap between the piezoelectric peripheral portion 1050 and the piezoelectric resonance layer 1051, and the piezoelectric peripheral portion 1050, piezoelectric The 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, a sacrificial material (not shown) can be covered on the piezoelectric peripheral portion 1050, the piezoelectric resonance layer 1051, and the second sacrificial layer 106 through a suitable process such as a coating process or a vapor deposition process. The thickness of the sacrificial material depends on Based on the protrusion height of the sacrificial protrusion 107 to be formed, the sacrificial material may 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., preferably the same material as the second sacrificial layer 106 to save costs and simplify the process; then, through a photolithography process or a photolithography combined etching process, the The sacrificial material is patterned to form sacrificial protrusions 107. The shape, size, and position of the sacrificial protrusions 107 determine the shape, size, and position of the top electrode protrusion to be formed later. Preferably, the sidewall of the sacrificial protrusion 107 is an inclined sidewall that is inclined relative to the plane of the piezoelectric resonance layer 1051 (that is, the top surface of the piezoelectric resonance layer 1051). The included angles θ1 and θ2 between the top surfaces are both less than or equal to 45 degrees, thereby facilitating the material coverage of the subsequent top electrode protruding portion 1081, avoiding breakage, and improving thickness uniformity. Further preferably, the line width of the sacrificial protrusion 107 is the minimum line width allowed by the corresponding process, and the horizontal distance between the sacrificial protrusion 107 and the piezoelectric resonance layer 1051 (the sacrificial protrusion 107 and the piezoelectric resonance The horizontal spacing of the layer 1051) is the minimum distance allowed by the corresponding process, thereby achieving a better transverse wave blocking effect and at the same time being beneficial to reducing the size of the device. In other embodiments of the present invention, the sacrificial protrusions 107 and the second sacrificial layer 106 can be formed by the same process, for example, the piezoelectric peripheral portion 1050, the piezoelectric resonance layer 1051, and the piezoelectric peripheral portion 1050 and the piezoelectric The second sacrificial layer 106 is covered in the gap between the resonant layers 1051, and the thickness of the second sacrificial layer 106 is not less than the sum of the thickness of the piezoelectric resonant layer 1051 and the thickness of the sacrificial protrusion 107; The two sacrificial layers 106 are patterned to form a second sacrificial layer 106 that is only filled in the gap between the piezoelectric peripheral portion 1050 and the piezoelectric resonance layer 1051, and a part of the second sacrificial layer 106 has sacrificial protrusions 107. The bottom surface of the sacrificial protrusion 107 may be flush with the top surface of the piezoelectric resonance layer 1051, and the top surface of the remaining part of the second sacrificial layer 106 is flush with the top surface of the piezoelectric resonance layer 1051.

1A, 1B, and 4E, 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 sacrificial protrusion 107 is covered with a top electrode material layer (not shown). For example, the top electrode material layer can be formed by magnetron sputtering, evaporation, or other physical vapor deposition or chemical vapor deposition methods. The thickness of the 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 material is etched using the photoresist layer as a mask 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 resonant portion 1082 covering the piezoelectric resonant layer 1051, a top electrode protruding portion 1081 covering the sacrificial protrusion 107, and a part of the top electrode protruding portion 1081 from the top electrode protruding portion 1081. The top surface of the second sacrificial layer 106 extends to the top electrode lap portion 1080 on the piezoelectric peripheral portion 1050 outside the top electrode protrusion 1081 and the top electrode peripheral portion separated from the top electrode resonance portion 1082 and the top electrode protrusion 1081 1083, 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 The overlap portion 1080 is separated to serve as a part of the overlap portion of the top electrode of the adjacent bulk acoustic wave resonator. In other embodiments of the present invention, the peripheral portion 1083 of the top electrode 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 1041 are completely sandwiched between, thereby facilitating 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 1041 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 protruding portion 1081 is arranged along at least one side of the top electrode resonant portion 1082 and connected to the corresponding side of the top electrode resonant portion 1082, that is, the top electrode protruding portion 1081 is along the top electrode. The sides of the resonance portion 1082 are arranged and at least arranged in the area where the top electrode lap portion 1080 and the top electrode resonance portion 1082 are aligned, for example, the top electrode protrusion 1081 surrounds the top electrode resonance portion 1082 to form a closed loop The structure (shown in FIGS. 2B and 2C), for example, the top electrode protrusion 1081 extends on multiple continuous sides of the top electrode resonance portion 1082 to form an open-loop structure (as shown in FIG. 2A). The top electrode lap portion 1080 is electrically connected to the side of the top electrode protrusion 1081 facing away from the top electrode resonance portion 1082, and passes through a portion of the second sacrificial layer 106 from the top electrode protrusion 1081. The top surface extends to the top surface of the part of the etching protection layer 101 outside the groove 102', the top electrode overlap portion 1080 and the bottom electrode overlap portion 1040 are staggered (that is, the two are in the area of the cavity 102). No overlap), and the top electrode lap portion 1080 and the bottom electrode lap portion 1040 respectively expose at least one side of the groove 102'. In an embodiment of the present invention, referring to FIGS. 1A and 2A, in the projection of the bottom surface of the groove 102', the projection of the top electrode protrusion 1081 at least exposes the bottom electrode resonance portion 1041 The projection of the boundary connected by the bottom electrode overlap portion 1040. The projections of the top electrode overlap portion 1080 and the bottom electrode overlap portion 1040 on the bottom surface of the groove 102' are just connected or separated from each other, and the top electrode overlap portion 1080 may only extend to the A part of the periphery of the groove 102' is above the substrate.

Please refer to FIGS. 1A, 1B and 4F. In step S6, photolithography combined with an etching process or a laser cutting process may be used in the piezoelectric peripheral portion 1050 facing the edge of the groove 102' or the periphery of the device area of the bulk acoustic wave resonator Drilling is performed to form a release hole (not shown) capable of exposing at least one of a part of the first sacrificial layer 103, a part of the sacrificial protrusion 107, or the second sacrificial layer 106 exposed by the sacrificial protrusion 107; Gas and/or liquid medicine are passed into the release hole to remove the sacrificial protrusion 107, the second sacrificial layer 106, and the first sacrificial layer 103, and then the second groove is re-emptied to form a cavity 102 The cavity 102 includes the space of the groove 102 ′, the increased space of the top electrode protrusion 1081 and the space under the top electrode protrusion 1081 that was originally occupied by the second sacrificial layer 106. Among them, the bottom electrode resonator 1041, the piezoelectric resonant layer 1051, and the top electrode resonator 1082 that are suspended above the cavity 102 and stacked in sequence form a monophonic sound film, and the bottom electrode resonator 1041, 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 1041 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 1041, 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 1041, 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 is also a parasitic transverse wave. The transverse wave will be blocked at the top electrode protrusion 1081 to confine the transverse wave in the effective working area 102A and prevent it from spreading to the air. In the film layer on the periphery of the cavity, the acoustic wave loss caused by the propagation of the transverse wave into the film layer on the periphery of the cavity is thereby improved, so that the quality factor of the resonator is improved, and the performance of the device can finally be improved.

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 of manufacturing the bulk acoustic wave resonator of the foregoing embodiments, the first sacrificial layer 103 is formed on a part of the liner by etching the substrate to form the groove 102' and filling the groove 102'. On the bottom, 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 the steps of other embodiments of the present invention In S1, 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 102 formed in step S6 is protruding on the entire substrate. For the cavity structure on the surface of the substrate, specifically, please refer to FIG. 2D and FIG. 5. In step S1, the groove 102' for making the cavity 102 is no longer formed in the provided substrate, but first 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 through a photolithography combined with etching process, and only the first sacrificial layer 103 covering the area 102 remains , And then form a first sacrificial layer 103 on a part of the substrate. The first sacrificial layer 103 may be a stepped structure with a narrow top and a wide bottom. The top surface of the first sacrificial layer 103 is flat, and the thickness of the first sacrificial layer 103 determines The depth of the cavity 102 subsequently formed. 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 4F, 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, at this time, the portion of the bottom electrode layer 104 located above the cavity 102 is flat and extending, that is, the top surface of the bottom electrode overlap portion 1040 located above the cavity (excluding the portion corresponding to the sidewall of the first sacrificial layer 103) and The top surface of the bottom electrode resonance portion 1041 is flush, and the bottom surface of the bottom electrode overlapping portion 1040 above the cavity (excluding the part corresponding to the sidewall of the first sacrificial layer 103) is flush with the bottom surface of the bottom electrode resonance portion 1041.

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 and the bottom electrode resonator portion are fabricated together, and the top electrode overlap portion, the top electrode convex portion and the top electrode The electrode resonance parts are manufactured at one time, 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

A bottom electrode layer is disposed on the substrate, and a cavity is formed between the bottom electrode layer and the substrate, and a portion of the bottom electrode layer above the cavity is flat and extended;

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

The top electrode layer is formed on the piezoelectric resonance layer, the top electrode layer has a top electrode protrusion, and the top electrode protrusion is located in the region of the cavity on the periphery of the piezoelectric resonance layer and Protruding in a direction away from the bottom surface of the cavity, and the top electrode protruding portion extends around the peripheral direction of the piezoelectric resonance layer.
The bulk acoustic wave resonator according to claim 1, wherein the bottom electrode layer comprises a bottom electrode resonant portion and a bottom electrode overlap portion, and the top surface of the bottom electrode resonant portion is flat and is connected to the piezoelectric resonant layer. Overlap, the bottom electrode overlapping portion extends flatly from one side of the bottom electrode resonant portion to above part of the substrate at the periphery of the cavity, and the top electrode layer further includes a top electrode resonant portion and a top electrode overlapping portion Connecting part, the top surface of the top electrode resonance part is flat and overlaps the piezoelectric resonance layer, the top electrode protruding part extends around the peripheral direction of the top electrode resonance part and is connected to the top electrode resonance part, so One end of the top electrode overlap portion is connected to the top electrode protrusion, and the other end is overlapped on the substrate surrounding the cavity; the bottom electrode overlap portion and the top electrode overlap portion are staggered with each other.
The bulk acoustic wave resonator according to claim 2, wherein 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 top electrode protruding portion is provided along the side of the top electrode resonant portion and is provided at least on the top electrode overlap portion and the top electrode In the area where the resonance parts are aligned.
The bulk acoustic wave resonator according to claim 4, wherein the top electrode protruding portion is at least offset from the bottom electrode overlap portion above the cavity, or the top electrode protruding portion Encircle the top electrode resonance part one round.
The bulk acoustic wave resonator according to claim 2, wherein the bottom electrode overlapping portion and the bottom electrode resonant portion are formed of the same film layer, and the top electrode protrusion portion and the top electrode overlap The part and the top electrode resonance part are formed using the same film layer.
The bulk acoustic wave resonator according to claim 3, 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 7, wherein the horizontal distance between the top electrode protrusion and the piezoelectric resonance layer is such that the top electrode protrusion is manufactured. The minimum distance allowed by the process.
The bulk acoustic wave resonator according to any one of claims 1 to 7, wherein the side wall of the top electrode protrusion is inclined with respect to the top surface of the piezoelectric resonance layer, and the top electrode protrusion The angle between the side wall of the part and the top surface of the piezoelectric resonance layer is less than or equal to 45 degrees.
7. The bulk acoustic wave resonator according to any one of claims 1 to 7, wherein the line width of the top electrode protrusion is the smallest line width allowed by the process of manufacturing the top electrode protrusion.
The bulk acoustic wave resonator according to any one of claims 1 to 7, wherein the cavity is a groove structure with an entire bottom recessed in the substrate or a whole protruding on the liner. Cavity structure on the bottom surface.
A filter, characterized by comprising at least one bulk acoustic wave resonator according to any one of claims 1 to 11.
A radio frequency communication system, characterized by comprising at least one filter according to claim 12.
A method for manufacturing a bulk acoustic wave resonator, characterized in that it comprises:

Providing a substrate, forming a first sacrificial layer with a flat top surface on part of the substrate;

Forming a bottom electrode layer on a part of the first sacrificial layer, and the part of the bottom electrode layer on the top surface of the first sacrificial layer extends flat;

Forming a piezoelectric resonance layer on the bottom electrode layer, the piezoelectric resonance layer exposing part of the first sacrificial layer and part of the bottom electrode layer;

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

Forming a top electrode layer on the piezoelectric resonance layer and a part of the second sacrificial layer around the piezoelectric resonance layer, and the part of the top electrode layer covering the sacrificial protrusion forms a top electrode protrusion;

The second sacrificial layer having the sacrificial protrusions and the first sacrificial layer are removed, a cavity is formed at the positions of the second sacrificial layer having the sacrificial protrusions and the first sacrificial layer, and the top electrode protrusions The portion is located in a cavity area on the periphery of the piezoelectric resonance layer and extends around the peripheral direction of the piezoelectric resonance layer.
The method of manufacturing a bulk acoustic wave resonator according to claim 14, wherein the step of forming a first sacrificial layer with a flat top surface on a part of the substrate comprises: etching the substrate to form a second groove In the substrate; forming a first sacrificial layer to fill in the second groove, and making the top surface of the first sacrificial layer flat; or,

The step of forming a first sacrificial layer on a part of the substrate includes: covering the first sacrificial layer on the substrate and planarizing the top surface of the first sacrificial layer; and patterning the first sacrificial layer to A first sacrificial layer is formed to protrude on part of the substrate.
The method for manufacturing a bulk acoustic wave resonator according to claim 14, wherein the step of removing the second sacrificial layer having the sacrificial protrusions and the first sacrificial layer 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 first sacrificial layer, part of the sacrificial protrusion, or part of the second sacrificial layer other than the sacrificial protrusion;

Gas and/or liquid medicine are passed into the release hole to remove the second sacrificial layer with the sacrificial protrusions and the first sacrificial layer.
The method for manufacturing a bulk acoustic wave resonator according to claim 14, wherein the step of forming the bottom electrode layer comprises: depositing a bottom electrode material layer to cover the first sacrificial layer and the periphery of the first sacrificial layer The bottom electrode material layer is patterned to form a bottom electrode lap portion and a bottom electrode resonant portion that are sequentially connected, the bottom electrode resonant portion overlaps the piezoelectric resonant layer, and the bottom electrode overlaps One end of the connecting portion is overlapped with the substrate on the periphery of the cavity, and the top surface of the portion where the bottom electrode overlap portion is located in the cavity area is flush with the bottom electrode resonance portion.
The method for manufacturing a bulk acoustic wave resonator according to claim 17, wherein the step of forming the top electrode layer comprises: depositing a top electrode material layer to cover the second sacrificial layer with the sacrificial protrusions and pressing On the electrical resonance layer; the top electrode material layer is patterned to form a top electrode lap portion, the top electrode protruding portion, and the top electrode resonant portion that are sequentially connected, the top electrode resonant portion and the piezoelectric resonance The layers overlap, the end of the top electrode lap portion facing away from the top electrode protrusion extends above the substrate on the periphery of the cavity, and the top electrode lap portion and the bottom electrode lap portion are mutually stagger.
The method for manufacturing a bulk acoustic wave resonator according to claim 18, wherein the bottom electrode resonator portion and the top electrode resonator portion are both polygonal, and the top electrode protruding portion resonates along the top electrode The edges of the part are arranged and at least arranged in the area where the top electrode overlap part and the top electrode resonance part are aligned.
The method for manufacturing a bulk acoustic wave resonator according to claim 14, wherein the horizontal distance between the top electrode protrusion and the piezoelectric resonance layer is determined by the process of manufacturing the top electrode protrusion. The minimum distance allowed.
The method for manufacturing a bulk acoustic wave resonator according to claim 14, wherein the line width of the top electrode protrusion is the minimum line width allowed by the process of manufacturing the top electrode protrusion.