WO2020199507A1 - 体声波谐振器及其制造方法和滤波器、射频通信系统 - Google Patents

体声波谐振器及其制造方法和滤波器、射频通信系统 Download PDF

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WO2020199507A1
WO2020199507A1 PCT/CN2019/105091 CN2019105091W WO2020199507A1 WO 2020199507 A1 WO2020199507 A1 WO 2020199507A1 CN 2019105091 W CN2019105091 W CN 2019105091W WO 2020199507 A1 WO2020199507 A1 WO 2020199507A1
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layer
top electrode
electrode
bottom electrode
cavity
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PCT/CN2019/105091
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English (en)
French (fr)
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罗海龙
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中芯集成电路（宁波）有限公司上海分公司
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Priority to JP2021525825A priority Critical patent/JP7138988B2/ja
Publication of WO2020199507A1 publication Critical patent/WO2020199507A1/zh
Priority to US17/449,836 priority patent/US12009803B2/en

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
    • H03H9/17—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
    • H03H9/17—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator
    • H03H9/171—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator implemented with thin-film techniques, i.e. of the film bulk acoustic resonator [FBAR] type
    • H03H9/172—Means for mounting on a substrate, i.e. means constituting the material interface confining the waves to a volume
    • H03H9/174—Membranes
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/46—Filters
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/46—Filters
    • H03H9/462—Microelectro-mechanical filters
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/46—Filters
    • H03H9/54—Filters comprising resonators of piezoelectric or electrostrictive material
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/46—Filters
    • H03H9/54—Filters comprising resonators of piezoelectric or electrostrictive material
    • H03H9/547—Notch filters, e.g. notch BAW or thin film resonator filters
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
    • H03H2009/155—Constructional features of resonators consisting of piezoelectric or electrostrictive material using MEMS techniques

Definitions

  • 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.
  • 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.
  • RF Radio frequency
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • the present invention provides a bulk acoustic wave resonator including:
  • 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 recessed portion, the top electrode recessed portion is located in the region of the cavity on the periphery of the piezoelectric resonance layer and is close to The direction of the bottom surface of the cavity is recessed, and the top electrode recessed 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:
  • top electrode 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 part of the top electrode layer covering the first groove forms a top electrode recess;
  • the second sacrificial layer and the first sacrificial layer are removed, the positions of the second sacrificial layer and the first sacrificial layer form a cavity, and the top electrode recess is located in the outer cavity of the piezoelectric resonance layer.
  • the cavity area extends around the peripheral direction of the piezoelectric resonance layer.
  • the piezoelectric phenomenon generated in the piezoelectric resonance layer 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 recess of the top electrode on the cavity on the periphery of the piezoelectric resonance layer, and be reflected back to the area corresponding to the piezoelectric resonance layer, thereby reducing and reducing the propagation of the transverse wave to the periphery of the cavity.
  • the loss caused when in the layer thereby improving the acoustic loss, so that the quality factor of the resonator is improved, and finally the performance of the device can be improved.
  • 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
  • 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.
  • the overlapped part is still a gap structure, which can greatly reduce the parasitic parameters and avoid the electric power of the top electrode layer and the bottom electrode layer in the cavity area. Problems such as contact can improve device reliability.
  • 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.
  • 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.
  • the recessed part of the top electrode surrounds the resonant 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.
  • the bottom electrode resonance part and the bottom electrode overlap part are formed by the same film layer, and the film thickness is uniform.
  • 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. This can simplify the process and reduce the cost, and because the film thickness of the top electrode recess is basically the same as other parts of the top electrode layer, the top electrode recess will not be broken, and the reliability of the device can be improved.
  • 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.
  • 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.
  • FIGS. 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.
  • FIG. 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.
  • 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
  • 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.
  • 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.
  • 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 second groove structure in the substrate.
  • the technology of the present invention is not limited to this. Please refer to FIG. 2D.
  • 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.
  • 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 recess portion 1081, and a top electrode resonant portion 1082 that are sequentially connected.
  • the bottom electrode resonant portion 1041, the top electrode resonant portion 1082 and the piezoelectric resonant 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 is excluding the effective working area 102A
  • the part is the invalid region 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 limit the effective working area of the bulk acoustic wave resonator in the cavity 102 area, and The influence of the film layer around the cavity on the longitudinal vibration generated by the piezoelectric resonance layer can be reduced, the parasitic parameters generated in the invalid region 102B can be reduced, and the device performance can be improved.
  • the bottom electrode resonant portion 1041, the piezoelectric resonant layer 1051, and the top electrode resonant portion 1082 are all flat structures with planar upper and lower surfaces.
  • the top electrode recess 1081 is located above the cavity 102B outside the effective working area 102A and is electrically connected
  • the top electrode resonance portion 1082 is recessed toward the bottom surface of the cavity 102.
  • the top electrode recessed portion 1081 is recessed downward 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 recess 1081 can be a solid structure or a hollow structure, preferably a hollow structure, which can make the film thickness of the top electrode layer 108 uniform, and avoid the solid top electrode recess 1081 from causing the top electrode resonance portion 1082 and its
  • the lower piezoelectric resonant layer 1051 and the bottom electrode resonant portion 1041 are deformed, thereby further improving the resonance factor.
  • 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.
  • 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 recess 1081 is arranged along the side of the top electrode resonant portion 1082 and is only provided in the area where the top electrode lap portion 1080 and the top electrode resonant portion 1082 are aligned, and the top electrode recess 1081 is equivalent to
  • the stacked structure of the bottom electrode resonant part 1041, the piezoelectric resonant layer 1051, and the top electrode resonant part 1082 in the effective area 102A is equivalent to the dial of a watch, except for the watch.
  • the belt part is connected to the film layer on the substrate surrounding the cavity, and the remaining part is separated from the film layer on the substrate surrounding the cavity through the cavity.
  • the top electrode recess 1081 extends around the peripheral direction of the piezoelectric resonance layer 1051, and the top electrode recess 1081 only surrounds a portion of the piezoelectric resonance layer 1051 along the peripheral direction of the piezoelectric resonance layer 1051.
  • the top electrode recessed portion 1081 and the bottom electrode overlapping portion 1040 are located on both sides of the piezoelectric resonance layer 1051 and are opposite, thereby achieving a certain transverse wave While the blocking effect, it can help reduce the area of the ineffective region 102B not covered by the top electrode lap 1080 and the bottom electrode lap 1040, thereby contributing to the reduction of the device size, and at the same time, the reduction of the top electrode
  • the area of the overlap portion 1080 and the bottom electrode overlap portion 1040 can 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.
  • 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 resonant portion 1082, and from The top electrode recessed portion 1081 is suspended above the cavity (ie 102B) outside the top electrode recessed portion 1081 and then extends to above the partial etching protection layer 101 on the periphery of the cavity 102; the bottom electrode overlaps
  • the portion 1040 and the top electrode overlap portion 1080 extend above the substrate outside the two opposite sides of the cavity 102.
  • the bottom electrode overlap portion 1040 and the top electrode overlap portion 1080 are in the hollow.
  • the regions of the cavity 102 are staggered (that is, they do not overlap), thereby reducing parasitic parameters, avoiding leakage and short circuit problems caused by contact between the bottom electrode laps and the top electrode laps, and 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 1041
  • the top electrode lap portion 1080 can be used to connect a corresponding signal line to pass the top electrode
  • the recessed portion 1081 transmits the corresponding signal to the top electrode resonance portion 1082, so that the bulk acoustic wave resonator can work normally.
  • 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.
  • the electrode resonance part 1082 applies 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. In this process, parasitic transverse waves are generated, which can be blocked by the top electrode recess 1081. These transverse waves propagate into the film layer on the periphery of the cavity and confine them within the area of the cavity 102, thereby avoiding energy loss caused by transverse waves and improving the quality factor.
  • the line width of the top electrode recess 1081 is the minimum line width allowed by the corresponding process, and the horizontal distance between the top electrode recess 1081 and the piezoelectric resonance layer 1051 is the minimum distance allowed by the corresponding process. Therefore, while the top electrode recess 1081 can achieve a certain transverse wave blocking effect, it can be beneficial to reduce the device area.
  • 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.
  • the clamps ⁇ 1 and ⁇ 2 between the two sidewalls of the top electrode recess 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 the top electrode recess
  • the sidewall of 1081 is too vertical to cause the top electrode recessed portion 1081 to break, thereby affecting the effect of signal transmission to the top electrode resonant portion 1082, and at the same time, the thickness uniformity of the entire top electrode layer 108 can be improved.
  • the bottom electrode resonance 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 resonance portion 1082, the top electrode recessed 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 resonates
  • the portion 1082, the top electrode recessed portion 1081 and the top electrode overlap portion 1080 are integrally fabricated layers, which can simplify the process and reduce the cost.
  • the bottom electrode resonator portion 1041 and the bottom electrode overlap portion 1040 can use any suitable conductive material or semiconductor material well known in the art, respectively, wherein the conductive
  • the 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).
  • the semiconductor material is Si, Ge, SiGe, SiC, SiGeC, etc.
  • 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 recess 1081 and the top electrode overlap portion 1080 can be formed by using different film production processes.
  • the top electrode recess 1081 extends to more continuous edges of the top electrode resonance portion 1082.
  • 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 resonant portion 1041 is the largest, the top electrode recessed portion 1081 is arranged along multiple sides of the top electrode resonant portion 1082 and connected to these sides, and the projection of the top electrode recessed portion 1081 on the bottom surface of the cavity 102 Expose the projection on the bottom surface of the cavity 102 where the bottom electrode resonator portion 1041 and the bottom electrode overlap portion 1040 are connected, so that the top electrode recess 1081 and the bottom electrode overlap portion 1040 do not overlap, and thus Reduce parasitic parameters.
  • 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 recess 1081 surrounds a circle of the top electrode resonance portion 1082, and the projections of the top electrode resonance portion 1082 and the bottom electrode resonance portion 1041 on the bottom surface of the cavity 102 coincide Therefore, the transverse wave generated by the piezoelectric resonance layer 1051 can be blocked in all directions through the closed annular DE top electrode recess 1081.
  • 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 recessed portion 1081 facing away from the top electrode resonant portion 1082, and is suspended from the top electrode recessed portion 1081 on the outside of the top electrode recessed portion 1081
  • the cavity (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 located on the cavity 102
  • the projections on the bottom surface may be directly connected or separated from
  • the top electrode overlap portion 1080 and the bottom electrode overlap portion 1040 do not overlap in the cavity 102 area and are staggered with each other.
  • 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.
  • 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.
  • the top electrode overlap portion 1080 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 overlap
  • 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 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.
  • the top electrode recessed 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 parasitic capacitance, improve device performance.
  • 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.
  • the shapes of the top electrode resonant portion 1082 and the bottom electrode resonant portion 1041 may not be similar, but it is preferable that the shape of the top electrode recess 1081 is the best It is adapted to the shape of the piezoelectric resonance layer 1051 and can extend along at least one side of the piezoelectric resonance layer 1051.
  • 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.
  • 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:
  • the top electrode recess 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.
  • step S1 of this embodiment the first sacrificial layer is formed on a part of the liner by etching the substrate to form a second groove and filling the second groove with material.
  • the specific implementation process includes:
  • a substrate is provided, specifically, a substrate 100 is provided, and an etching protection layer 101 is covered on the substrate 100.
  • 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.
  • 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.
  • RIE reactive ion etching
  • 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.
  • 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.
  • 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.
  • the first sacrificial layer 103 can be Ge, and the first The sacrificial layer 103 may also cover the etch protection layer 101 on the periphery of the second groove or the top surface is higher than the top surface of the etch protection layer 101 around the second groove; then, through a chemical mechanical planarization (CMP) process, The top of the first sacrificial layer 103 is planarized to the top surface of the etch protection layer 101, so that the first sacrificial layer 103 is only located in the second groove 102', and the first sacrificial layer The top surface of 103 is flush with the top surface of the surrounding etching protection layer 101, thereby providing a flat process surface for subsequent formation of the bottom electrode layer 104 with a flat surface.
  • CMP chemical mechanical planarization
  • 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.
  • 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 surface of the second groove 102' extends to the bottom electrode overlap 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.
  • the bottom electrode peripheral portion 1042 can be connected to the bottom electrode
  • the electrode overlap 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 overlap portion 1040 as an adjacent body A part of the bottom electrode overlap portion of the acoustic wave resonator, in other embodiments of the present invention, the bottom electrode peripheral portion 1042 may be omitted.
  • the top-view shape of the bottom electrode resonance portion 1041 may be a pentagon, and in other embodiments of the present invention, it may also be a quadrilateral or hexagonal shape.
  • the bottom electrode lap portion 1040 is electrically connected to at least the bottom electrode resonance portion 1041.
  • the bottom electrode layer 104 extends flat in the global scope, that is, the bottom electrode resonance portion 1041 and the bottom electrode overlapping portion 1040 have a flush bottom surface and a flush top surface.
  • the bottom electrode layer 104 extends flat in the global scope, that is, the bottom electrode resonance portion 1041 and the bottom electrode overlapping portion 1040 have a flush bottom surface and a flush top surface.
  • 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.
  • RF radio frequency
  • 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.
  • 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 piezo
  • 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.
  • 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).
  • Sc scandium
  • Er erbium
  • Y yttrium
  • La lanthanum
  • 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. ⁇ 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 lap portion 1040 and around the bottom electrode resonance portion 1041, and further pass through the formed gap
  • the piezoelectric peripheral portion 1050 can also realize the subsequent formation of the top electrode peripheral portion and the previously formed bottom electrode peripheral portion 1042 The isolation between them also provides a relatively flat process surface for the subsequent formation of the second sacrificial layer and the top electrode layer.
  • 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
  • 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.
  • 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, ⁇ 2 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.
  • 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.
  • the first groove 107 and the bottom electrode overlap portion do not have an overlapping part in the vertical direction
  • there may be a certain amount of over-etching so that The bottom surface of the formed first groove 107 is stopped within a certain thickness of the first sacrificial layer 103 to ensure that the transverse wave in the thickness of the piezoelectric resonance layer 1051 can be blocked.
  • 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.
  • the material of the first sub-sacrificial layer can be converted into another material after being processed by some processes.
  • the first sub-sacrificial layer The layer can be a semiconductor material, and the gap is formed by a chemical vapor deposition process.
  • 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
  • CMP chemical mechanical planarization
  • the bulk acoustic wave resonator to be fabricated can be etched by a process of photolithography and etching, and the etching can be 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.
  • 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).
  • the top electrode material layer can be formed by magnetron sputtering, vapor deposition or other physical vapor deposition or chemical vapor deposition methods.
  • 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.
  • 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 1041 are completely sandwiched between, thereby facilitating the reduction of the device size and the reduction of parasitic parameters.
  • 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.
  • RF radio frequency
  • the top electrode layer 108 can be used as an output electrode
  • 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.
  • 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.
  • the top electrode recess 1081 surrounds the top electrode resonance portion 1082 to form a closed loop structure (such as 2B and 2C), for another example, the top electrode recess 1081 extends on a plurality of 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 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'.
  • the top electrode recessed portion 1081 and the bottom electrode overlap portion 1040 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.
  • 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 zone to form at least one release hole (not shown) capable of exposing part of the first sacrificial layer 103 or part of the second sacrificial layer 106; then, gas and/or medicine are introduced into the release hole.
  • 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.
  • 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.
  • a bulk acoustic wave is generated by a piezoelectric phenomenon generated in the piezoelectric resonance layer 1051.
  • a parasitic transverse wave 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 recess 1081, confining the transverse wave in the effective working area 102A and preventing it from propagating to 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.
  • 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.
  • 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.
  • 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'. 103 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.
  • the technical solution of the present invention is not limited to this.
  • 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 as a whole
  • the cavity structure protruding on the surface of the substrate specifically, please refer to FIG. 2D and FIG. 5.
  • a second groove for making the cavity 102 is no longer formed in the provided substrate 102', but firstly cover the first sacrificial layer 103 on the etching protection layer 101 on the surface of the substrate 100; then the first sacrificial layer 103 is patterned by photolithography combined with an etching process, leaving only the area 102 covered
  • the first sacrificial layer 103 is further formed 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 first sacrificial layer 103
  • the thickness of the layer 103 determines the depth of the cavity 102 to be subsequently formed.
  • 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.
  • 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 overlapping part and the bottom electrode resonance part are made together, and the top electrode overlapping part, the top electrode recessed part and the top electrode The resonant parts are manufactured together, thereby simplifying the process and reducing the manufacturing cost.

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Abstract

一种体声波谐振器及其制造方法和滤波器、射频通信系统，形成于压电谐振层（1051）外围的且悬空于空腔（102）上方的顶电极凹陷部（1081），能够阻挡压电谐振层（1051）产生的横波向空腔（102）外围传输，将横波反射回有效工作区（102A）中，继而减少和降低了声波损耗，使谐振器的品质因子得到提高，最终能够提高器件性能。进一步地，底电极搭接部（1040）和顶电极搭接部（1080）与空腔（102）的重叠部分均是悬空的，且底电极搭接部（1040）和顶电极搭接部（1080）相互错开，可以大大降低寄生参数，并避免漏电、短路等问题，能够提高器件可靠性。

Description

体声波谐振器及其制造方法和滤波器、射频通信系统 技术领域
本发明涉及射频通信技术领域，尤其涉及一种体声波谐振器及其制造方法和滤波器、射频通信系统。
背景技术
射频(RF)通信，如在移动电话中使用的通信，需要运用射频滤波器，每一个射频滤波器都能传递所需的频率，并限制所有其他频率。随着移动通信技术的发展，移动数据传输量也迅速上升。因此，在频率资源有限以及应当使用尽可能少的移动通信设备的前提下，提高无线基站、微基站或直放站等无线功率发射设备的发射功率成了必须考虑的问题，同时也意味着对移动通信设备前端电路中滤波器功率的要求也越来越高。
目前，无线基站等设备中的大功率滤波器主要是以腔体滤波器为主，其功率可达上百瓦，但是这种滤波器的尺寸太大。也有的设备中使用介质滤波器，其平均功率可达5瓦以上，这种滤波器的尺寸也很大。由于尺寸大，所以这两种滤波器无法集成到射频前端芯片中。
随着MEMS技术越来越成熟，由体声波(BAW)谐振器构成的滤波器，能够很好地克服了上述两种滤波器存在的缺陷。体声波谐振器具有陶瓷介质滤波器不可比拟的体积优势、声表面波(SAW)谐振器不可比拟的工作频率以及功率容量的优势，成为了当今无线通信系统的发展趋势。
体声波谐振器的主体部分为底电极-压电薄膜-顶电极构成的“三明治”结构，利用压电薄膜的逆压电效应将电能转化成机械能，并以声波的形式在体声波谐振器构成的滤波器中形成驻波。由于声波的速度比电磁波小5个数量级，因此体声波谐振器构成的滤波器的尺寸比传统的介质滤波器等小。
其中一种空腔型体声波谐振器，其工作原理是利用声波在底电极或支撑层与空气的交界面发生反射，将声波限制在压电层，实现谐振，其具有高Q值、低插损、可集成等优点，被广泛采用。
但是，目前制作出的空腔型体声波谐振器，其品质因子(Q)无法进一步提高，因此无法满足高性能的射频系统的需求。
发明内容
本发明的目的在于提供一种体声波谐振器及其制造方法和滤波器、射频通信系统，能够提高品质因子，进而提高器件性能。
为了实现上述目的，本发明提供一种体声波谐振器包括：
衬底；
底电极层，设置在所述衬底上，且所述底电极层和所述衬底之间形成有空腔，所述底电极层位于所述空腔的上方的部分是平坦延伸的；
压电谐振层，形成在所述空腔上方的部分所述底电极层上；
顶电极层，形成在所述压电谐振层上，所述顶电极层具有顶电极凹陷部，所述顶电极凹陷部位于所述压电谐振层外围的所述空腔的区域中并向着靠近所述空腔的底面的方向凹陷，所述顶电极凹陷部围绕所述压电谐振层的周边方向延伸。
本发明还提供一种滤波器，包括至少一个如本发明所述的体声波谐振器。
本发明还提供一种射频通信系统，包括至少一个如本发明所述的滤波器。
本发明还提供一种体声波谐振器的制造方法，包括：
提供衬底，形成顶面平坦的第一牺牲层于部分所述衬底上；
形成底电极层于部分所述第一牺牲层上，且所述底电极层位于所述第一牺牲层顶面上的部分是平坦延伸的；
形成压电谐振层于所述底电极层上，所述压电谐振层暴露出部分所述第一牺牲层和部分所述底电极层；
形成具有第一凹槽的第二牺牲层于所述压电谐振层周围暴露出的区域中；
形成顶电极层于所述压电谐振层及压电谐振层周围的部分第二牺牲层上，所述顶电极层覆盖在所述第一凹槽上的部分形成顶电极凹陷部；
去除所述第二牺牲层和所述第一牺牲层，所述第二牺牲层和所述第一牺牲层的位置形成空腔，所述顶电极凹陷部位于所述压电谐振层外围的空腔区域中且围绕所述压电谐振层的周边方向延伸。
与现有技术相比，本发明的技术方案，具有以下有益效果：
1、当电能施加到底电极和顶电极时，通过在压电谐振层中产生的压电现象而产生期望的沿着厚度方向传播的纵波以及不期望的沿着压电谐振层平面传播 的横波，该横波会在悬空于压电谐振层外围的空腔上的顶电极凹陷部处受到阻挡，被反射回压电谐振层所对应的区域中，继而减少和降低了横波传播到空腔外围的膜层中时造成的损失，由此改善声波损耗，使谐振器的品质因子得到提高，最终能够提高器件性能。
2、压电谐振层的周边与空腔的周边相互分离，即压电谐振层不会连续延伸到空腔外围的衬底上方，能够将体声波谐振器的有效工作区完全限制在空腔区域中，且底电极搭接部和顶电极搭接部均只会延伸到空腔的部分边上(即底电极层和顶电极层不会对空腔全面覆盖)，由此能够减少空腔周围的膜层对压电谐振层产生的纵向振动的影响，提高性能。
3、顶电极凹陷部即使和底电极层有相互重叠的部分，重叠的部分之间也是空隙结构，由此可以大大降低寄生参数，并避免顶电极层和底电极层在空腔区域中的电接触等问题，能够提高器件可靠性。
4、底电极搭接部和顶电极搭接部与空腔的重叠部分均是悬空的，且底电极搭接部和顶电极搭接部在空腔的区域中相互错开(即二者在空腔区域不重叠)，由此可以大大降低寄生参数，并避免底电极搭接部和顶电极搭接部相接触而引起的漏电、短路等问题，能够提高器件可靠性。
5、所述底电极搭接部在自身所处的空腔部分上方完全遮盖空腔，由此，可以利用大面积的底电极搭接部来对其上方的膜层进行强有力的机械支撑，从而避免因空腔坍塌而器件失效的问题。
6、顶电极凹陷部围绕顶电极谐振部一周，可以从压电谐振层的周边全方位的阻挡横波，进而获得较佳的品质因子。
7、底电极谐振部和底电极搭接部采用同一膜层形成，且膜厚均匀，顶电极凹陷部、顶电极谐振部以及顶电极搭接部采用同一膜层形成，且膜厚均匀，由此能够简化工艺，降低成本，且因为顶电极凹陷部的膜厚和顶电极层的其他部分基本相同，因此不会出现顶电极凹陷部断裂的情况，能够提高器件的可靠性。
8、底电极层在空腔区域的部分平坦，一方面能够有利于提高有效区中的薄膜的厚度均一性，另一方面有利于降低形成压电谐振层时的刻蚀工艺的难度，避免因底电极层的顶面不平而出现压电材料刻蚀残留的问题，从而减小寄生参数。
附图说明
图1A是本发明一实施例的体声波谐振器的俯视结构示意图。
图1B和图1C是沿图1中的XX’和YY’线的剖面结构示意图。
图2A至图2C是本发明其他实施例的体声波谐振器的俯视结构示意图。
图2D是本发明另一实施例的体声波谐振器的剖面结构示意图。
图3是本发明一实施例的体声波谐振器的制造方法的流程图。
图4A至图4F是本发明一实施例的体声波谐振器的制造方法中沿图1A中的XX’的剖面示意图。
图5是本发明另一实施例的体声波谐振器的制造方法中沿图1A中的XX’的剖面示意图。
其中，附图标记如下：
100-基底；101-刻蚀保护层；102-空腔；102’-第二凹槽；102A-有效工作区；102B-无效区；103-第一牺牲层；104-底电极层(即剩余的底电极材料层)；1040-底电极搭接部；1041-底电极谐振部；1042-底电极外围部；105-压电材料层；1050-压电外围部；1051-压电谐振层(或称为压电谐振部)；106-第二牺牲层；107-第一凹槽；108-顶电极层(即剩余的顶电极材料层)；1080-顶电极搭接部；1081-顶电极凹陷部；1082-顶电极谐振部；1083-顶电极外围部。
具体实施方式
以下结合附图和具体实施例对本发明的技术方案作进一步详细说明。根据下面的说明，本发明的优点和特征将更清楚。需说明的是，附图均采用非常简化的形式且均使用非精准的比例，仅用以方便、明晰地辅助说明本发明实施例的目的。类似的，如果本文所述的方法包括一系列步骤，且本文所呈现的这些步骤的顺序并非必须是可执行这些步骤的唯一顺序，且一些所述的步骤可被省略和/或一些本文未描述的其他步骤可被添加到该方法。另外本文中的某物与某物“相互错开”的含义是两者在空腔区域不重叠，即两者向空腔的底面上的投影不重叠。
请参考图1A至图1C，图1A为本发明一实施例的体声波谐振器的俯视结构示意图，图1B是沿图1中的XX’的剖面结构示意图，图1C是沿图1A中的YY’线的剖面结构示意图，本实施例的体声波谐振器包括：衬底、底电极层104、 压电谐振层1051和顶电极层108。
其中，所述衬底包括基底100以及覆盖在所述基底100上的刻蚀保护层101。所述基底100可以为本领域技术人员熟知的任意合适的底材，例如可以是以下所提到的材料中的至少一种：硅(Si)、锗(Ge)、锗硅(SiGe)、碳硅(SiC)、碳锗硅(SiGeC)、砷化铟(InAs)、砷化镓(GaAs)、磷化铟(InP)或者其它III/V化合物半导体，还包括这些半导体构成的多层结构等，或者为绝缘体上硅(SOI)、绝缘体上层叠硅(SSOI)、绝缘体上层叠锗化硅(S-SiGeOI)、绝缘体上锗化硅(SiGeOI)以及绝缘体上锗(GeOI)，或者还可以为双面抛光硅片(Double Side Polished Wafers，DSP)，也可为氧化铝等的陶瓷基底、石英或玻璃基底等。所述刻蚀保护层101的材料可以是任意适合的介电材料，包括但不限于氧化硅、氮化硅、氮氧化硅、碳氮化硅等材料中的至少一种，该刻蚀保护层一方面可以用于增加最终制造的体声波谐振器的结构稳定性，增加了体声波谐振器与基底100之间的隔离，可以降低对基底100的电阻率要求，另一方面还以在制造体声波谐振器的过程中保护衬底其他区域不受刻蚀，从而提高器件性能与可靠性。
底电极层104和衬底之间形成有空腔102。请参考图1A至图1C，在本实施例中，所述空腔102可以通过刻蚀工艺依次刻蚀所述刻蚀保护层101和部分厚度的基底100而形成，成为一个整个底部凹陷在所述衬底中的第二凹槽结构。但本发明的技术不仅仅限定于此，请参考图2D，在本发明的另一实施例中，所述空腔102也可以采用将凸设于刻蚀保护层101表面上的牺牲层通过后去除方法去除的工艺形成在刻蚀保护层101的顶面上方，成为一个整体上凸设在所述刻蚀保护层101表面上的腔体结构。此外，本实施例中，空腔102的底面的形状为矩形，但在本发明的其他实施例中，空腔102的底面形状还可以是圆形、椭圆形或是矩形以外的多边形，例如五边形、六边形等。
压电谐振层1051也可以称为压电谐振部，位于所述空腔102的上方区域中(也可以说是位于所述空腔102的区域中)，对应体声波谐振器的有效工作区，且压电谐振层1051设置在底电极层104和顶电极层108之间。底电极层104包括依次连接的底电极搭接部1040和底电极谐振部1041，底电极层104位于所述空腔102上方的部分是平坦延伸的，即底电极搭接部1040位于空腔上方的部分的顶面和所述底电极谐振部1041的顶面齐平，底电极搭接部1040位于空腔上方的部分的底面和所述底电极谐振部1041的底面齐平。顶电极层108包括依次 连接的顶电极搭接部1080、顶电极凹陷部1081以及顶电极谐振部1082，底电极谐振部1041、顶电极谐振部1082均与压电谐振层1051重叠，且所述空腔102与重叠在一起的底电极谐振部1041、压电谐振层1051、顶电极谐振部1082对应的区域构成所述体声波谐振器的有效工作区102A，空腔102除有效工作区102A以外的部分为无效区102B，压电谐振层1051位于有效工作区102A中并与空腔102周围的膜层分离，能够将体声波谐振器的有效工作区完全限制在空腔102的区域中，并能够减少空腔周围的膜层对压电谐振层产生的纵向振动的影响，降低无效区102B中产生的寄生参数，提高器件性能。底电极谐振部1041、压电谐振层1051、顶电极谐振部1082均为上下表面是平面的平坦结构，所述顶电极凹陷部1081位于所述有效工作区102A外围的空腔102B上方并电连接所述顶电极谐振部1082，且向着靠近所述空腔102的底面的方向凹陷。顶电极凹陷部1081整体上相对顶电极谐振部1082的顶面向下凹陷且位于所述压电谐振层1051外围的空腔区域(即102B)中。顶电极凹陷部1081可以是实心结构，也可以是空心结构，优选为空心结构，由此能使得顶电极层108的膜厚均匀，避免实心的顶电极凹陷部1081引起顶电极谐振部1082及其下方的压电谐振层1051和底电极谐振部1041下榻变形，继而进一步改善谐振因子。其中，所述底电极谐振部1041、所述顶电极谐振部1082均为多边形(顶面和底面均为多边形)，且所述底电极谐振部1041、所述顶电极谐振部1082的形状可以相似(如图2A及2C所示)或者完全相同(如图1A和图2B所示)。压电谐振层1051为与所述底电极谐振部1041、所述顶电极谐振部1082的形状相似的多边形结构。
请参考图1A至图1C，在本实施例中，底电极层104、压电谐振层1051以及顶电极层108构成一个“手表”形状的膜层结构，底电极搭接部1040和底电极谐振部1041的一个角对齐，顶电极搭接部1080和顶电极谐振部1082的一个角对齐，底电极搭接部1040和顶电极搭接部1080相当于“手表”的两个表带，所述顶电极凹陷部1081沿着所述顶电极谐振部1082的边设置且仅设置在所述顶电极搭接部1080和所述顶电极谐振部1082对齐的区域中，所述顶电极凹陷部1081相当于“手表”的表盘与一个表带之间的连接结构，有效区102A中的底电极谐振部1041、压电谐振层1051、顶电极谐振部1082堆叠结构相当于手表的表盘，该表盘除了表带部分与空腔周围衬底上的膜层相接外，其余部分均通过空腔与空腔周围衬底上的膜层相分离。即本实施例中，顶电极凹陷部1081 围绕所述压电谐振层1051的周边方向延伸且所述顶电极凹陷部1081仅沿压电谐振层1051的周边方向围绕在压电谐振层1051的部分边上，且以压电谐振层1051所在的平面为参考，所述顶电极凹陷部1081和所述底电极搭接部1040分居压电谐振层1051两侧且相对，由此在实现一定的横波阻挡效果的同时，能够有利于顶电极搭接部1080和底电极搭接部1040未覆盖的无效区102B的面积的减小，进而有利于器件尺寸的减小，同时还有利于减小顶电极搭接部1080和底电极搭接部1040的面积，以进一步减少寄生参数，提高器件的电学性能。所述底电极搭接部1040电连接所述底电极谐振部1041的一侧，并从所述底电极谐振部1041上经悬空于底电极谐振部1041外侧的空腔(即102B)上方后延伸到所述空腔102外围的部分刻蚀保护层101的上方；所述顶电极搭接部1080电连接所述顶电极凹陷部1081背向所述顶电极谐振部1082的一侧，并从所述顶电极凹陷部1081上经悬空于所述顶电极凹陷部1081外侧的空腔(即102B)上方后延伸到所述空腔102外围的部分刻蚀保护层101上方；所述底电极搭接部1040和所述顶电极搭接部1080延伸到所述空腔102的两相对的边外侧的衬底上方，此时所述底电极搭接部1040和所述顶电极搭接部1080在空腔102区域中相互错开(即二者不重叠)，由此，可以降低寄生参数，并避免底电极搭接部和顶电极搭接部相接触而引起的漏电、短路等问题，提高器件性能。所述底电极搭接部1040可以用于连接相应的信号线，以向底电极谐振部1041传递相应的信号，所述顶电极搭接部1080可以用于连接相应的信号线，以通过顶电极凹陷部1081向顶电极谐振部1082传递相应的信号，从而使得体声波谐振器可以正常工作，具体地，通过底电极搭接部1040、顶电极搭接部1080分别向底电极谐振部1041和顶电极谐振部1082施加时变电压来激发纵向延伸模式或“活塞”模式，压电谐振层1051将电能形式的能量转换成纵波，在此过程中会产生寄生的横波，顶电极凹陷部1081可以阻挡这些横波向空腔外围的膜层中传播，将其限制在空腔102的区域内，从而避免横波引起的能量损耗，提高品质因子。
优选地，顶电极凹陷部1081的线宽分别为对应的工艺所允许的最小线宽，顶电极凹陷部1081与压电谐振层1051之间的水平距离均为对应的工艺所允许的最小距离，由此在使得顶电极凹陷部1081能够实现一定的横波阻挡效果的同时，能有利于减小器件面积。
此外，所述顶电极凹陷部1081的侧壁相对所述压电谐振层的顶面为倾斜侧 壁，如图1B所示，所述顶电极凹陷部1081沿图1A中XX’线的截面为梯形或类梯形，所述顶电极凹陷部1081的两个侧壁与所述压电谐振层1051的顶面之间的夹α1、α2均小于等于45度，由此，避免因顶电极凹陷部1081的侧壁过于竖直而造成顶电极凹陷部1081断裂，进而影响向顶电极谐振部1082上传输信号的效果，同时还能够提高整个顶电极层108的厚度均一性。
在本发明的一个优选实施例中，底电极谐振部1041和底电极搭接部1040采用同一膜层的制作工艺(即同一道膜层制作工艺)形成，顶电极谐振部1082、顶电极凹陷部1081以及顶电极搭接部1080采用同一膜层的制作工艺(即同一道膜层制作工艺)形成，即底电极谐振部1041和底电极搭接部1040为一体式制作的膜层，顶电极谐振部1082、顶电极凹陷部1081和顶电极搭接部1080为一体式制作的膜层，由此可以简化工艺，降低成本，其中，用于制作底电极谐振部1041和底电极搭接部1040的膜层材料和用于制作顶电极谐振部1082、顶电极凹陷部1081和顶电极搭接部1080的膜层材料可以分别使用本领域技术任意熟知的任意合适的导电材料或半导体材料，其中，导电材料可以为具有导电性能的金属材料，例如，铝(Al)、铜(Cu)、铂金(Pt)、金(Au)、钼(Mo)、钨(W)、铱(Ir)、锇(Os)、铼(Re)、钯(Pd)、铑(Rh)及钌(Ru)中的一种或几种，所述半导体材料例如Si、Ge、SiGe、SiC、SiGeC等。在本发明的其他实施例中，在工艺成本和工艺技术允许的前提下，底电极谐振部1041和底电极搭接部1040也可以采用不同的膜层制作工艺形成，顶电极谐振部1082、顶电极凹陷部1081以及顶电极搭接部1080可以采用不同的膜层制作工艺形成。
请参考图2A至图2C，为了进一步提高横波阻挡效果，顶电极凹陷部1081延伸到顶电极谐振部1082的更多连续的边上。例如，请参考图2A，压电谐振层1051、顶电极谐振部1082以及底电极谐振部1041均为五边形的平面结构，且压电谐振层1051的面积最小，顶电极谐振部1082次之，底电极谐振部1041的面积最大，所述顶电极凹陷部1081沿顶电极谐振部1082的多个边设置并连接到这些边上，且顶电极凹陷部1081在空腔102的底面上的投影暴露所述底电极谐振部1041与所述底电极搭接部1040连接的部分在空腔102的底面上的投影，由此使得顶电极凹陷部1081与底电极搭接部1040不重叠，进而可以降低寄生参数。再例如，请参考图2B，压电谐振层1051、顶电极谐振部1082以及底电极谐振部1041均为五边形的平面结构，且压电谐振层1051的面积最小， 顶电极谐振部1082和底电极谐振部1041的面积、形状等相同或基本相同，顶电极凹陷部1081包围顶电极谐振部1082的一周，且顶电极谐振部1082和底电极谐振部1041在空腔102底面上的投影重合，由此，可以通过呈封闭的环形DE顶电极凹陷部1081来对压电谐振层1051产生的横波进行全方位阻挡。
请参考图2A至2C，在本发明的这些实施例中，所述底电极搭接部1040电连接所述底电极谐振部1041的至少一个边或至少一个角，并从所述底电极谐振部1041的相应边上经悬空于所述底电极谐振部1041外侧的空腔(即102B)上方后延伸到所述空腔102外围的部分刻蚀保护层101的上方；所述顶电极搭接部1080电连接所述顶电极凹陷部1081背向所述顶电极谐振部1082的至少一个边或至少一个角，并从所述顶电极凹陷部1081上经悬空于所述顶电极凹陷部1081外侧的空腔(即102B)上方后延伸到所述空腔102外围的部分刻蚀保护层101上方，且所述顶电极搭接部1080和所述底电极搭接部1040在所述空腔102的底面上的投影可以正好相接，也可以相互分离，由此，所述顶电极搭接部1080和所述底电极搭接部1040在空腔102的区域上无重叠而相互错开。例如图1A、图2A～2B所示，底电极搭接部1040可以仅延伸到所述空腔102的一条边外围的部分衬底的上方，所述顶电极搭接部1080仅延伸到所述空腔102的一条边外围的部分衬底的上方，且所述顶电极搭接部1080和所述底电极搭接部1040在所述空腔102的底面上的投影相互分离，由此避免所述顶电极搭接部1080和所述底电极搭接部1040重叠时引入寄生参数以及有可能引起的漏电、短路等问题。但优选地，请参考图2C，所述底电极搭接部1040沿着所述底电极谐振部1041的所有边设置并连续延伸到所述空腔102外围的衬底上，由此使得底电极搭接部1040能够延伸到所述空腔102外围的更多方向上的部分衬底的上方，即此时，所述底电极搭接部1040在自身所处的空腔部分上方完全遮盖空腔102，从而可以通过大面积的底电极搭接部1040的铺设来增强对有效工作区102A的膜层的支撑力，防止空腔102的坍塌。进一步优选地，当所述底电极搭接部1040延伸到所述空腔102外围的更多方向上的部分衬底的上方时，所述顶电极搭接部1080仅延伸到所述空腔102外围的一个方向上的部分衬底的上方，例如空腔102的俯视形状为矩形时，所述顶电极搭接部1080仅延伸到空腔102的一条边外围的衬底上方，底电极搭接部1040延伸到与所述空腔102的另外三条边上，且此时所述顶电极搭接部1080和所述底电极搭接部1040在所述空腔102的底面上的 投影正好相接或相互分离，即此时，所述底电极搭接部1040在自身所处的空腔部分上方完全遮盖空腔102，且在所述顶电极搭接部1080的宽度方向，与所述顶电极搭接部1080无重叠，由此避免大面积顶电极搭接部1080的设置会与底电极搭接部1040等结构在垂直方向上发生重叠而引入过多的寄生参数，进而可以进一步提高器件的电学性能和可靠性。
在本发明的各个实施例中，当所述空腔102的俯视形状为多边形时，底电极搭接部1040和顶电极搭接部1080分别暴露出所述空腔的至少一个边，由此使得连接有底电极搭接部1040的底电极谐振部1041和连接有顶电极凹陷部1081的顶电极谐振部1082分别有至少一端是完全悬空的，这样可以有利于减小无效区102B的面积，进而减小无效区102B中产生的寄生电容等寄生参数，提高器件性能。优选地，所述顶电极凹陷部1081在所述空腔102上方至少与所述底电极搭接部1040相互错开(即二者在空腔区域不重叠)，由此进一步降低无效区102B中产生的寄生电容等寄生参数，提高器件性能。
需要说明的是，为了达到最好的横波阻挡效果且有利于小尺寸器件的制作，顶电极凹陷部1081越靠近有效工作区102A越好，顶电极凹陷部1081的线宽越小越好，优选地，顶电极凹陷部1081的线宽为对应的工艺所允许的最小线宽，顶电极凹陷部1081与有效工作区102A(即与压电谐振层1051)的水平距离为对应的工艺所允许的最小距离。
值得注意的是，上述各实施例中，顶电极谐振部1082和底电极谐振部1041形状相似或相同且面积相同，或底电极谐振部1041面积大于顶电极谐振部1082的面积，但是本发明的技术方案并不仅仅限定于此，在本发明的其他实施例中，顶电极谐振部1082和底电极谐振部1041的形状也可以不相似，但是优选的是，顶电极凹陷部1081的形状最好是与压电谐振层1051的形状相适配，其能够沿压电谐振层1051的至少一个边延伸。
另外，经我们研究发现，体声波谐振器的寄生横波大部分会通过有效工作区102A上的膜层与空腔外围的衬底之间的连接结构来传递，因此本发明各实施例中，在保证能够对有效工作区102A的膜层进行有效支撑的前提下，可以尽量控制顶电极搭接部1080的面积(或者说线宽)最小，底电极搭接部1040的面积(或者说线宽)最小。
本发明一实施例还提供一种滤波器，包括至少一个如上述的任意本发明实 施例所述的体声波谐振器。
本发明一实施例还提供一种射频通信系统，包括至少一个如本发明一实施例所述的滤波器。
请参考图3，本发明一实施例还提供一种本发明的体声波谐振器(例如图1A至图2C所示的体声波谐振器)的制造方法，包括：
S1，提供衬底，形成顶面平坦的第一牺牲层于部分所述衬底上；
S2，形成底电极层于部分所述第一牺牲层上，且所述底电极层位于所述第一牺牲层顶面上的部分是平坦延伸的；
S3，形成压电谐振层于所述底电极层上，所述压电谐振层暴露出部分所述第一牺牲层和部分所述底电极层；
S4，形成具有第一凹槽的第二牺牲层于所述压电谐振层周围暴露出的区域中；
S5，形成顶电极层于所述压电谐振层及压电谐振层周围的部分第二牺牲层上，所述顶电极层覆盖在所述第一凹槽上的部分形成顶电极凹陷部；
S6，去除具有所述第一凹槽的第二牺牲层和所述第一牺牲层，具有所述第一凹槽的第二牺牲层和所述第一牺牲层的位置形成空腔，所述顶电极凹陷部位于所述压电谐振层外围的空腔区域中且围绕所述压电谐振层的周边方向延伸。
请参考图1A、1B和图4A至4B，在本实施例的步骤S1中，通过刻蚀衬底形成第二凹槽以及向第二凹槽中填充材料的工艺形成第一牺牲层于部分衬底上，具体实现过程包括：
首先，请参考图1A和图4A，提供衬底，具体地，提供一基底100，并在基底100上覆盖刻蚀保护层101。其中，所述刻蚀保护层101可以通过任意适合的工艺方法例如热氧化、热氮化、热氧氮化等热处理方法或者化学气相沉积、物理气相沉积或原子层沉积等沉积方法形成于基底100上。进一步地，刻蚀保护层101的厚度可以根据实际器件工艺需要进行合理设定，在此不做具体限定。
接着，请继续参考图1A、1B和图4A，通过光刻和刻蚀工艺，对衬底进行刻蚀，以形成至少一个第二凹槽102’。该刻蚀工艺可以是湿法刻蚀或者干法刻蚀工艺，其中较佳地使用干法刻蚀工艺，干法刻蚀包括但不限于反应离子刻蚀(RIE)、离子束刻蚀、等离子体刻蚀或者激光切割。第二凹槽102’的深度和形状均取决于待制造的体声波谐振器所需空腔的深度和形状，第二凹槽102’的横截 面形状为矩形，在本发明的其他实施例中，第二凹槽102’的横截面还可以是其他任意合适的形状，例如是圆形、椭圆形或者矩形除外的其他多边形(如五边形、六边形等)。
然后，请参考图1A、1B和图4B，可以通过气相沉积、热氧化、旋涂或外延生长等工艺填充第一牺牲层103于所述第二凹槽102’中，所述第一牺牲层103可以选取为不同于基底100和刻蚀保护层101的半导体材料、介电材料或光阻材料等，例如当基底100为Si基底，第一牺牲层103可以为Ge，此时形成的第一牺牲层103可能还覆盖在第二凹槽外围的刻蚀保护层101上或者顶面高于第二凹槽周围的刻蚀保护层101顶面；然后，通过化学机械平坦化(CMP)工艺，将所述第一牺牲层103的顶部平坦化至所述刻蚀保护层101的顶面，以使得所述第一牺牲层103仅位于第二凹槽102’中，且所述第一牺牲层103的顶面与其周围的刻蚀保护层101的顶面齐平，由此为后续形成具有平坦表面的底电极层104提供平坦的工艺表面。
请参考图1A、1B和4C，在步骤S2中，首先，可以根据预定形成的底电极的材料选择适合的方法在刻蚀保护层101、第一牺牲层103的表面上覆盖底电极材料层(未图示)，例如可以通过磁控溅射、蒸镀等物理气相沉积或者化学气相沉积方法形成底电极材料层；然后，利用光刻工艺在底电极材料层上形成定义有底电极图案的光刻胶层(未图示)，再以光刻胶层为掩膜，刻蚀所述底电极材料层，以形成底电极层(即剩余的底电极材料层)104，之后，将光刻胶层去除。底电极材料层可以使用本领域技术任意熟知的任意合适的导电材料或半导体材料，其中，导电材料可以为具有导电性能的金属材料，例如，铝(Al)、铜(Cu)、铂金(Pt)、金(Au)、钼(Mo)、钨(W)、铱(Ir)、锇(Os)、铼(Re)、钯(Pd)、铑(Rh)及钌(Ru)中的一种或几种，所述半导体材料例如Si、Ge、SiGe、SiC、SiGeC等。本实施例中，底电极层(剩余的底电极材料层)104包括覆盖在后续形成的有效工作区102A上的底电极谐振部1041、从底电极谐振部1041的一侧经第一牺牲层103的表面延伸到第二凹槽102’外侧的部分刻蚀保护层101上的底电极搭接部1040以及与底电极谐振部1041分离的底电极外围部1042，该底电极外围部1042可以与底电极搭接部1040背向底电极谐振部1041的一侧连接，以用做该区域待形成的体声波谐振器的一个金属接点，也可以与底电极搭接部1040分离，作为相邻的体声波谐振器的底电极搭接部的一部分，在本发明的其他实施例中， 底电极外围部1042可以被省略。底电极谐振部1041的俯视形状可以是五边形，在本发明的其他实施例中，还可以是四边形或者六边形等，所述底电极搭接部1040电连接底电极谐振部1041的至少一个边或至少一个角，并从所述底电极谐振部1041的相应边上经底电极谐振部1041外侧的第一牺牲层103的顶面后延伸到所述第二凹槽102’外围的部分刻蚀保护层101的顶面上，此外，由于本实施例中第一牺牲层103的顶面和刻蚀保护层101的顶面齐平，因此可以使得形成的所述底电极层104的底面齐平、顶面也齐平，此时所述底电极层104在全局范围内均平坦延伸，即底电极谐振部1041和底电极搭接部1040具有齐平的底面和齐平的顶面。优选地，如图2C，所述底电极搭接部1040在自身所处的空腔部分上方完全遮盖空腔102，且在所述顶电极搭接部1080的宽度方向，与所述顶电极搭接部1080无重叠，以提高对后续膜层的支撑力，并尽量避免和所述顶电极搭接部1080重叠而引入不必要的寄生参数。底电极谐振部1041可用作接收或提供诸如射频(RF)信号等的电信号的输入电极或者输出电极。
请参考图1A、1B和图4C，在步骤S3中，首先，可以使用化学气相沉积、物理气相沉积或原子层沉积等本领域技术人员熟知的任何适合的方法沉积形成压电材料层105；然后，利用光刻工艺在压电材料层105上形成定义有压电薄膜图案的光刻胶层(未图示)，再以光刻胶层为掩膜，刻蚀所述压电材料层105，以形成压电谐振层1051，之后，将光刻胶层去除。所述压电材料层105的材料可以使用氮化铝(AlN)、氧化锌(ZnO)、锆钛酸铅(PZT)、铌酸锂(LiNbO 3)、石英(Quartz)、铌酸钾(KNbO 3)或钽酸锂(LiTaO 3)等具有纤锌矿型结晶结构的压电材料及它们的组合。当压电材料层105包括氮化铝(AlN)时，压电材料层105还可包括稀土金属，例如钪(Sc)、铒(Er)、钇(Y)和镧(La)中的至少一种。此外，当压电材料层105包括氮化铝(AlN)时，压电材料层105还可包括过渡金属，例如锆(Zr)、钛(Ti)、锰(Mn)和铪(Hf)中的至少一种。图案化后剩余的压电材料层105包括相互分离的压电谐振层1051和压电外围部1050，压电谐振层1051位于底电极谐振部1041上，暴露出底电极搭接部1040，且可以完全覆盖或者部分覆盖底电极谐振部1041。压电谐振层1051的形状可以与底电极谐振部1041的形状相同，也可以不同，其俯视形状可以是五边形，也可以是其他多边形，例如四边形、六边形、七边形或者八边形等。压电外围部1050能够和压电谐振层1051之间形成间隙，以暴露出底电极搭接部1040上方以及所述底电极谐振部1041 周围的部分第一牺牲层103，并进一步通过形成的间隙来限制后续第二牺牲层的形成区域，同时为后续第一凹槽的形成提供相对平坦的工艺表面，压电外围部1050还可以实现后续形成的顶电极外围部和之前形成底电极外围部1042之间的隔离，同时为后续第二牺牲层和顶电极层的形成提供相对平坦的工艺表面。
请参考图1A、1B和图4D，在步骤S4中，首先，可以通过涂覆工艺或者气相沉积工艺等合适的工艺，在压电外围部1050、压电谐振层1051以及压电外围部1050和压电谐振层1051之间的间隙中覆盖第二牺牲层106，且第二牺牲层106能填满压电外围部1050与压电谐振层1051之间的间隙，该第二牺牲层106的材料可以选自非晶碳、光刻胶、介电材料(例如氮化硅、碳氧化硅、多孔材料等)或半导体材料(例如多晶硅、非晶硅、锗)等中的至少一种，第二牺牲层106的材质优选为不同于第一牺牲层103，以能够在后续形成第一凹槽107的刻蚀工艺中，利用第一牺牲层103的顶面作为刻蚀停止点，进而控制后续形成的第一凹槽107的深度；然后，通过CMP工艺对第二牺牲层106进行顶部平坦化，以使得第二牺牲层106仅填充在压电外围部1050与压电谐振层1051之间的间隙中，且压电外围部1050、压电谐振层1051和第二牺牲层106构成平坦的上表面。在本发明的其他实施例中，也可以通过回刻蚀工艺去除压电外围部1050与压电谐振层1051上表面上的第二牺牲层106，使其仅填充在压电外围部1050与压电谐振层1051之间的间隙中。然后，通过光刻工艺或者光刻结合刻蚀的工艺，将第二牺牲层106进行图案化，形成第一凹槽107，第一凹槽107的形状、大小以及位置等决定了后续形成的顶电极凹陷部的形状、大小以及位置等。优选地，第一凹槽107的侧壁为相对压电谐振层1051所在平面倾斜的倾斜侧壁，第一凹槽107的侧壁与压电谐振层1051的顶面之间的夹角θ1、θ2均小于等于45度，由此，有利于后续顶电极凹陷部1081的材料覆盖，避免出现断裂，提高厚度均一性。进一步优选地，第一凹槽107的线宽为对应的工艺所允许的最小线宽，第一凹槽107与所述压电谐振层1051之间的水平距离为对应的工艺所允许的最小距离，由此在实现较佳的横波阻挡效果的同时，有利于减小器件尺寸。在本发明的其他实施例中，当第一凹槽107和底电极搭接部在垂直方向不具有重叠部分时，对第二牺牲层106进行刻蚀后，可以存在一定的过刻蚀，使得形成的第一凹槽107的底面停止在第一牺牲层103的一定厚度中，以保证能够对压电谐振层1051厚度上的横波进行阻挡。
在本发明的其他实施例中，所述第二牺牲层106包括材质不同且自下而上堆叠的第一子牺牲层(未图示)和第二子牺牲层(未图示)，第一子牺牲层和第二子牺牲层的设置，能够使得后续在刻蚀形成第一凹槽时能精确控制刻蚀的停止点，进而精确控制后续形成的顶电极凹陷部1081的凹陷深度，由此可见，第二子牺牲层的厚度决定了后续形成的顶电极凹陷部1081的凹陷深度。其中可以采用以下步骤形成具有第一子牺牲层、第二子牺牲层和第一凹槽107的第二牺牲层106，包括：首先，通过气相沉积或外延生长工艺填充第一子牺牲层于所述压电谐振层1051和压电外围部1050之间的间隙中，所述第一子牺牲层选材为能够被一些工艺处理后转化为另一种材料，本实施例中所述第一子牺牲层可以为半导体材料，并通过化学气相沉积工艺形成间隙中，此时所述第一子牺牲层不仅填满压电谐振层1051和压电外围部1050之间的间隙，还覆盖在压电谐振层1051和压电外围部1050的上表面上；然后，通过化学机械平坦化(CMP)工艺，将所述第一子牺牲层的顶部平坦化至压电谐振层1051和压电外围部1050的顶面，以使得所述第一子牺牲层仅位于压电谐振层1051和压电外围部1050之间的间隙中；接着，根据第一子牺牲层的材质选取合适的表面改性处理工艺，例如包括氧化处理、氮化处理和离子注入中的至少一种，对所述第一子牺牲层的顶部一定厚度进行表面改性处理，以使得这部分厚度的第一子牺牲层转化为另一种材质的第二子牺牲层，所述第二子牺牲层及其下方未被表面改性处理的剩余的所述第一子牺牲层构成填满所述压电谐振层1051和压电外围部1050之间的间隙的第二牺牲层106，第二子牺牲层的厚度取决于后续需要形成的顶电极凹陷部1081的凹陷深度；之后，由于表面处理工艺可能会使得填充的第二牺牲层106的顶面与其周围的压电谐振层1051的顶面不再齐平，不利于后续顶电极层108的沉积，因此需要通过化学机械平坦化(CMP)工艺，进一步将所述第二子牺牲层的顶部平坦化至所述压电谐振层1051的顶面，以使得所述第二牺牲层106的顶面与其周围的压电谐振层1051的顶面再次齐平，以为后续工艺提供相对平坦的操作表面。然后，可以通过光刻结合刻蚀的工艺刻蚀第二牺牲层106对应待制作的体声波谐振器的有效工作区(如图4F中的102A)外围中的第二子牺牲层，刻蚀可以停止在第一子牺牲层的顶面，也可以存在一定的过刻蚀，以停止在第一子牺牲层中，进而形成第一凹槽107。
请参考图1A、图1B和图4E，在步骤S5中，首先，可以根据预定形成的 顶电极的材料选择适合的方法在压电外围部1050、压电谐振层1051、第二牺牲层106以及第一凹槽107的表面上覆盖顶电极材料层(未图示)，例如可以通过磁控溅射、蒸镀等物理气相沉积或者化学气相沉积方法形成顶电极材料层，顶电极材料层可以在各个位置厚度均一；然后，利用光刻工艺在顶电极材料层上形成定义有顶电极图案的光刻胶层(未图示)，再以光刻胶层为掩膜，刻蚀所述顶电极材料层，以形成顶电极层(即图案化的顶电极材料层或剩余的顶电极材料层)108，之后，将光刻胶层去除。顶电极材料层可以使用本领域技术任意熟知的任意合适的导电材料或半导体材料，其中，导电材料可以为具有导电性能的金属材料，例如，Al、Cu、Pt、Au、Mo、W、Ir、Os、Re、Pd、Rh及Ru中的一种或几种，所述半导体材料例如Si、Ge、SiGe、SiC、SiGeC等。本实施例中，顶电极层108包括覆盖在压电谐振层1051上的顶电极谐振部1082、覆盖在第一凹槽107上的顶电极凹陷部1081、从顶电极凹陷部1081经部分第二牺牲层106的顶面延伸到顶电极凹陷部1081外侧的压电外围部1050上的顶电极搭接部1080以及与顶电极谐振部1082、顶电极凹陷部1081均分离的顶电极外围部1083，该顶电极外围部1083可以与顶电极搭接部1080背向顶电极谐振部1082的一侧连接，以用做该区域待形成的体声波谐振器的一个金属接点，也可以与顶电极搭接部1080分离，以作为相邻的体声波谐振器的顶电极搭接部的一部分，在本发明的其他实施例中，顶电极外围部1083可以被省略。顶电极谐振部1082的俯视形状可以与压电谐振层1051的形状相同，也可以不同，其俯视形状例如为五边形，其面积优选为大于压电谐振层1051，以使得压电谐振层1051被顶电极谐振部1082和底电极谐振部1041完全夹在中间，从而有利于器件尺寸的减小以及寄生参数的降低，在本发明的其他实施例中，顶电极谐振部1082的形状还可以是四边形、六边形、七边形或者八边形等多边形。顶电极层108可用作接收或提供诸如射频(RF)信号等的电信号的输入电极或输出电极。例如，当底电极层104用作输入电极时，顶电极层108可用作输出电极，并且当底电极层104用作输出电极时，顶电极层108可用作输入电极，压电谐振层1051将通过顶电极谐振部1082或底电极谐振部1041上输入的电信号转换为体声波。例如，压电谐振层1051通过物理振动将电信号转换为体声波。顶电极凹陷部1081沿着所述顶电极谐振部1082的至少一个边设置并连接到所述顶电极谐振部1082的相应边上，即所述顶电极凹陷部1081沿着所述顶电极谐振部1082的边设置且 至少设置在所述顶电极搭接部1080和所述顶电极谐振部1082对齐的区域中，例如顶电极凹陷部1081环绕所述顶电极谐振部1082一周而构成闭环结构(如图2B和2C所示)，再例如顶电极凹陷部1081在所述顶电极谐振部1082的多个连续边上延伸而构成开环结构(如图2A所示)。所述顶电极搭接部1080电连接所述顶电极凹陷部1081背向所述顶电极谐振部1082的一侧，并从所述顶电极凹陷部1081上经部分第二牺牲层106的顶面延伸到第二凹槽102’外侧的部分刻蚀保护层101的顶面，所述顶电极搭接部1080和所述底电极搭接部1040相互错开(即二者在空腔102的区域上不重叠)，且所述顶电极搭接部1080和所述底电极搭接部1040分别暴露出第二凹槽102’的至少一个边。在本发明的一实施例中，请参考图1A和图2A，在垂直于所述第二凹槽102’的底面的方向上，所述顶电极凹陷部1081与所述底电极搭接部1040面向所述底电极谐振部1041的边不重叠。所述顶电极搭接部1080和所述底电极搭接部1040在所述第二凹槽102’的底面上的投影正好相接或相互分离，所述顶电极搭接部1080可以仅延伸到所述第二凹槽102’的一条边外围的部分衬底的上方。
请参考图1A、1B和图4F，在步骤S6中，可以通过光刻结合刻蚀工艺或者激光切割工艺，在压电外围部1050面向第二凹槽102’的边缘或者体声波谐振器的器件区外围进行打孔，以形成能够暴露出部分第一牺牲层103或部分第二牺牲层106的至少一个释放孔(未图示)；然后，向所述释放孔中通入气体和/或药液，以去除所述第二牺牲层106和所述第一牺牲层103，进而重新清空第二凹槽以形成空腔102，该空腔102包括第二凹槽102’的空间及顶电极凹陷部1081下方的原先被第二牺牲层106占据的空间。其中，悬空于空腔102上方且依次层叠的底电极谐振部1041、压电谐振层1051和顶电极谐振部1082组成独立体声薄膜，且底电极谐振部1041、压电谐振层1051、顶电极谐振部1082和空腔102沿着竖直方向彼此重叠的部分为有效区域，定义为有效工作区102A，在该有效工作区102A中，当诸如射频信号的电能施加到底电极谐振部1041和顶电极谐振部1082时，会因在压电谐振层1051中产生的压电现象而在压电谐振层1051的厚度方向(即纵向)上产生振动和谐振，空腔102的其他区域为无效区102B，在该无效区102B中，即使当电能施加到顶电极层108和底电极层104时也不因压电现象而谐振的区域。悬空于有效工作区102A上方且依次层叠的底电极谐振部1041、压电谐振层1051和顶电极谐振部1082组成的独立体声薄膜能够输出 与压电谐振层1051的压电现象的振动对应的谐振频率的射频信号。具体地，当电能施加到顶电极谐振部1082和底电极谐振部1041时，通过在压电谐振层1051中产生的压电现象而产生体声波。在这种情况下，从产生的体声波除了期望的纵波还有寄生的横波，该横波会在顶电极凹陷部1081处被阻挡，将横波限制在有效工作区102A中，防止其传播到空腔外围的膜层中，由此改善因横波向空腔外围的膜层中传播而引起的声波损耗，从而使谐振器的品质因子得到提高，最终能够提高器件性能。
需要说明的是，步骤S6可以在待形成的空腔102上方的所有膜层均制作完成后再执行，由此，可以继续利用第一牺牲层103和第二牺牲层106来保护空腔102所在的空间以及其上形成的底电极层104至顶电极层108堆叠的膜层结构，以避免在空腔102形成之后继续进行后续工艺时造成的空腔坍塌风险。此外，在步骤S6中形成的释放孔，可以先一直保留，使得释放孔能够利用后续的两衬底键合等的封装工艺来密封，进而使得空腔102封闭。
需要注意的是，上述各实施例的体声波谐振器的制造方法的步骤S1中，通过刻蚀衬底形成第二凹槽102’和填充第二凹槽102’的工艺来形成第一牺牲层103于部分衬底上，以使得步骤S6中形成的空腔102为整个底部凹陷在所述衬底中的凹槽结构，但本发明的技术方案并不仅仅限定于此，在本发明的其他实施例的步骤S1中，还可以通过膜层沉积结合光刻和刻蚀工艺来形成整体上凸设于衬底上的第一牺牲层103，以使得步骤S6形成中的空腔102为整体上凸设在所述衬底表面上的腔体结构，具体地，请参考图2D和图5，在步骤S1中，在提供的衬底中不再形成用于制作空腔102的第二凹槽102’，而是先在基底100表面的刻蚀保护层101上覆盖第一牺牲层103；然后通过光刻结合刻蚀的工艺，将第一牺牲层103图案化，仅保留覆盖在区域102上的第一牺牲层103，进而形成第一牺牲层103于部分衬底上，该第一牺牲层103可以是上窄下宽的台阶结构，第一牺牲层103的顶面平坦，且第一牺牲层103的厚度决定了后续形成的空腔102的深度。在该实施例中，后续步骤与图4A至图4F所示的实施例的体声波谐振器的制造方法中的相应部分完全相同，在此不再赘述，只是形成的底电极外围部1043、底电极搭接部1040、压电外围部1050、顶电极外围部1083、顶电极搭接部1080的相应侧壁需要适应凸立的第一牺牲层103而变形，纵向截面均变为“Z”形结构，此时，底电极层104位于空腔102上方的部分是平坦延 伸的，即底电极搭接部1040位于空腔上方(不包括对应第一牺牲层103侧壁的部分)的顶面和底电极谐振部1041的顶面齐平，底电极搭接部1040位于空腔上方(不包括对应第一牺牲层103侧壁的部分)的底面和底电极谐振部1041的底面齐平。
本发明的体声波谐振器优选地采用本发明的体声波谐振器的制作方法，以将底电极搭接部与底电极谐振部一道制作，将顶电极搭接部、顶电极凹陷部和顶电极谐振部一道制作，进而简化工艺，降低制作成本。
显然，本领域的技术人员可以对发明进行各种改动和变型而不脱离本发明的精神和范围。这样，倘若本发明的这些修改和变型属于本发明权利要求及其等同技术的范围之内，则本发明也意图包含这些改动和变型在内。

Claims (21)

  1. 一种体声波谐振器，其特征在于，包括：
    衬底；
    底电极层，设置在所述衬底上，且所述底电极层和所述衬底之间形成有空腔，所述底电极层位于所述空腔的上方的部分是平坦延伸的；
    压电谐振层，形成在所述空腔上方的部分所述底电极层上；
    顶电极层，形成在所述压电谐振层上，所述顶电极层具有顶电极凹陷部，所述顶电极凹陷部位于所述压电谐振层外围的所述空腔的区域中并向着靠近所述空腔的底面的方向凹陷，所述顶电极凹陷部围绕所述压电谐振层的周边方向延伸。
  2. 如权利要求1所述的体声波谐振器，其特征在于，所述底电极层包括底电极谐振部和底电极搭接部，所述底电极谐振部顶面平坦且与所述压电谐振层重叠，所述底电极搭接部从所述底电极谐振部的一侧平坦地延伸到所述空腔外围的部分衬底的上方，所述顶电极层还包括顶电极谐振部以及顶电极搭接部，所述顶电极谐振部顶面平坦且与所述压电谐振层重叠，所述顶电极凹陷部围绕所述顶电极谐振部的周边方向延伸并连接所述顶电极谐振部，所述顶电极搭接部一端连接所述顶电极凹陷部，另一端搭接到所述空腔外围的衬底上；所述底电极搭接部和所述顶电极搭接部相互错开。
  3. 如权利要求2所述的体声波谐振器，其特征在于，所述底电极谐振部和所述顶电极谐振部均为多边形。
  4. 如权利要求3所述的体声波谐振器，其特征在于，所述顶电极凹陷部沿着所述顶电极谐振部的边设置且至少设置在所述顶电极搭接部和所述顶电极谐振部对齐的区域中。
  5. 如权利要求4所述的体声波谐振器，其特征在于，所述顶电极凹陷部在所述空腔上方至少与所述底电极搭接部相互错开，或者，所述顶电极凹陷部环绕所述顶电极谐振部一周。
  6. 如权利要求2所述的体声波谐振器，其特征在于，所述底电极搭接部和所述底电极谐振部采用同一膜层形成，所述顶电极凹陷部、所述顶电极搭接部和所述顶电极谐振部采用同一膜层形成。
  7. 如权利要求3所述的体声波谐振器，其特征在于，所述底电极搭接部在自身所处的空腔部分上方完全遮盖空腔，且在所述顶电极搭接部的宽度方向，与所述顶电极搭接部无重叠。
  8. 如权利要求1至7中任一项所述的体声波谐振器，其特征在于，所述顶电极凹陷部与所述压电谐振层之间的水平距离为制造所述顶电极凹陷部的工艺所允许的最小距离。
  9. 如权利要求1至7中任一项所述的体声波谐振器，其特征在于，所述顶电极凹陷部的侧壁相对所述压电谐振层的顶面倾斜，所述顶电极凹陷部的侧壁和所述压电谐振层的顶面之间的夹角小于等于45度。
  10. 如权利要求1至7中任一项所述的体声波谐振器，其特征在于，所述顶电极凹陷部的线宽为制造所述顶电极凹陷部的工艺所允许的最小线宽。
  11. 如权利要求1至7中任一项所述的体声波谐振器，其特征在于，所述空腔为整个底部凹陷在所述衬底中的第二凹槽结构或者为整体上凸设在所述衬底表面上的腔体结构。
  12. 一种滤波器，其特征在于，包括至少一个如权利要求1至11中任一项所述的体声波谐振器。
  13. 一种射频通信系统，其特征在于，包括至少一个如权利要求12所述的滤波器。
  14. 一种体声波谐振器的制造方法，其特征在于，包括：
    提供衬底，形成顶面平坦的第一牺牲层于部分所述衬底上；
    形成底电极层于部分所述第一牺牲层上，且所述底电极层位于所述第一牺牲层顶面上的部分是平坦延伸的；
    形成压电谐振层于所述底电极层上，所述压电谐振层暴露出部分所述第一牺牲层和部分所述底电极层；
    形成具有第一凹槽的第二牺牲层于所述压电谐振层周围暴露出的区域中；
    形成顶电极层于所述压电谐振层及压电谐振层周围的部分第二牺牲层上，所述顶电极层覆盖在所述第一凹槽上的部分形成顶电极凹陷部；
    去除所述第二牺牲层和所述第一牺牲层，所述第二牺牲层和所述第一牺牲层的位置形成空腔，所述顶电极凹陷部位于所述压电谐振层外围的空腔区域中且围绕所述压电谐振层的周边方向延伸。
  15. 如权利要求14所述的体声波谐振器的制造方法，其特征在于，形成顶面平坦的第一牺牲层于部分衬底上的步骤包括：刻蚀所述衬底，以形成第二凹槽于所述衬底中；形成第一牺牲层填充于所述第二凹槽中，且使得所述第一牺牲层的顶面平坦；或者，
    形成第一牺牲层于部分衬底上的步骤包括：覆盖第一牺牲层于所述衬底上并对所述第一牺牲层的顶面进行平坦化；图案化所述第一牺牲层，以形成第一牺牲层凸设于部分衬底上。
  16. 如权利要求14所述的体声波谐振器的制造方法，其特征在于，去除所述第二牺牲层和所述第一牺牲层的步骤包括：
    在形成顶电极层之后，形成至少一个释放孔，所述释放孔至少暴露出部分所述第一牺牲层或部分所述第二牺牲层；
    向所述释放孔中通入气体和/或药液，以去除所述第二牺牲层和所述第一牺牲层。
  17. 如权利要求14所述的体声波谐振器的制造方法，其特征在于，形成所述底电极层的步骤包括：沉积底电极材料层覆盖于所述第一牺牲层和所述第一牺牲层外围的衬底上；图案化所述底电极材料层，以形成依次连接的底电极搭接部和底电极谐振部，所述底电极谐振部与所述压电谐振层重叠，所述底电极搭接部一端搭接到所述空腔外围的衬底上，且所述底电极搭接部位于空腔区域的部分的顶面和所述底电极谐振部齐平。
  18. 如权利要求17所述的体声波谐振器的制造方法，其特征在于，形成所述顶电极层步骤包括：沉积顶电极材料层覆盖于具有所述第一凹槽的所述第二牺牲层以及压电谐振层上；图案化所述顶电极材料层，以形成依次连接的顶电极搭接部、所述顶电极凹陷部和顶电极谐振部，所述顶电极谐振部与所述压电谐振层重叠，所述顶电极搭接部背向所述顶电极凹陷部的一端延伸到所述空腔外围的衬底上方，且所述顶电极搭接部和所述底电极搭接部相互错开。
  19. 如权利要求18所述的体声波谐振器的制造方法，其特征在于，所述底电极谐振部和所述顶电极谐振部均为多边形，所述顶电极凹陷部沿着所述顶电极谐振部的边设置且至少设置在所述顶电极搭接部和所述顶电极谐振部对齐的区域中。
  20. 如权利要求14所述的体声波谐振器的制造方法，其特征在于，所述顶 电极凹陷部与所述压电谐振层之间的水平距离为制造所述顶电极凹陷部的工艺所允许的最小距离。
  21. 如权利要求14所述的体声波谐振器的制造方法，其特征在于，所述顶电极凹陷部的线宽为制造所述顶电极凹陷部的工艺所允许的最小线宽。
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