WO2021012917A1 - 薄膜体声波谐振器及其制造方法和滤波器、射频通信*** - Google Patents

薄膜体声波谐振器及其制造方法和滤波器、射频通信*** Download PDF

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Publication number
WO2021012917A1
WO2021012917A1 PCT/CN2020/099647 CN2020099647W WO2021012917A1 WO 2021012917 A1 WO2021012917 A1 WO 2021012917A1 CN 2020099647 W CN2020099647 W CN 2020099647W WO 2021012917 A1 WO2021012917 A1 WO 2021012917A1
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Prior art keywords
electrode
layer
bulk acoustic
area
piezoelectric
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PCT/CN2020/099647
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English (en)
French (fr)
Inventor
隋欢
齐飞
杨国煌
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中芯集成电路（宁波）有限公司
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Priority to JP2021503042A priority Critical patent/JP7081041B2/ja
Publication of WO2021012917A1 publication Critical patent/WO2021012917A1/zh
Priority to US17/198,698 priority patent/US20210281243A1/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
    • H03H9/02—Details
    • H03H9/02007—Details of bulk acoustic wave devices
    • H03H9/02015—Characteristics of piezoelectric layers, e.g. cutting angles
    • 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
    • H03H9/56—Monolithic crystal 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
    • H03H9/02—Details
    • H03H9/02007—Details of bulk acoustic wave devices
    • H03H9/02086—Means for compensation or elimination of undesirable effects
    • H03H9/02118—Means for compensation or elimination of undesirable effects of lateral leakage between adjacent resonators
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
    • H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
    • H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/02007—Details of bulk acoustic wave devices
    • H03H9/02047—Treatment of substrates
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/05—Holders; Supports
    • H03H9/0504—Holders; Supports for bulk acoustic wave devices
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/125—Driving means, e.g. electrodes, coils
    • H03H9/13—Driving means, e.g. electrodes, coils for networks consisting of piezoelectric or electrostrictive materials
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/125—Driving means, e.g. electrodes, coils
    • H03H9/13—Driving means, e.g. electrodes, coils for networks consisting of piezoelectric or electrostrictive materials
    • H03H9/131—Driving means, e.g. electrodes, coils for networks consisting of piezoelectric or electrostrictive materials consisting of a multilayered structure
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/125—Driving means, e.g. electrodes, coils
    • H03H9/13—Driving means, e.g. electrodes, coils for networks consisting of piezoelectric or electrostrictive materials
    • H03H9/132—Driving means, e.g. electrodes, coils for networks consisting of piezoelectric or electrostrictive materials characterized by a particular shape
    • 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
    • H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
    • H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
    • H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
    • H03H2003/023—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks the resonators or networks being of the membrane type

Definitions

  • the invention relates to the field of semiconductor device manufacturing, in particular to a thin film bulk acoustic wave resonator, a manufacturing method thereof, a filter, and a radio frequency communication system.
  • radio frequency front-end modules have gradually become the core components of communication equipment.
  • the filter has become the component with the strongest growth momentum and the greatest development prospects.
  • the performance of the filter is determined by the resonator unit that makes up the filter.
  • the film bulk acoustic resonator (FBAR) has the characteristics of small size, low insertion loss, large out-of-band suppression, high quality factor, high operating frequency, large power capacity, and good resistance to electrostatic shock. Become one of the most suitable filters for 5G applications.
  • the film bulk acoustic wave resonator includes two film electrodes, and a piezoelectric film layer is arranged between the two film electrodes. Its working principle is to use the piezoelectric film layer to generate vibration under an alternating electric field.
  • the bulk acoustic wave propagating in the thickness direction of the electric film layer this sound wave is reflected back at the interface between the upper and lower electrodes and the air, and then reflected back and forth inside the film, forming an oscillation.
  • a standing wave oscillation is formed.
  • the quality factor (Q) of the currently manufactured cavity-type thin-film 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 thin film bulk acoustic wave resonator, a manufacturing method thereof, a filter, and a radio frequency communication system, which can improve the quality factor of the thin film bulk acoustic wave resonator, thereby improving the performance of the device.
  • the present invention provides a thin film bulk acoustic resonator, including:
  • the piezoelectric laminate covering the cavity includes a first electrode, a piezoelectric layer, and a second electrode sequentially disposed on the support layer.
  • the piezoelectric laminate includes an effective layer located above the center of the cavity. A resonance zone and an ineffective resonance zone surrounding the effective resonance zone;
  • At least two trenches are distributed at the junction of the effective resonance region and the ineffective resonance region to define the range of the effective resonance region.
  • the trench includes a first trench and a second trench, and the second trench penetrates the The second electrode and the piezoelectric layer, and the first groove penetrates the first electrode and the piezoelectric layer and communicates with the cavity.
  • the present invention also provides a filter including at least one of the thin film bulk acoustic wave resonators.
  • the present invention also provides a filter, a radio frequency communication system, including at least one of the filters.
  • the present invention also provides a method for manufacturing a thin-film bulk acoustic wave resonator for a filter, including: providing a second substrate, forming a piezoelectric stack on the second substrate, and the piezoelectric stack includes sequentially forming A second electrode layer, a piezoelectric layer, and a first electrode layer on the second substrate;
  • a support layer is formed on the first electrode layer, a cavity with an opening is formed in the support layer to expose a part of the first electrode layer, and the first electrode layer and the piezoelectric layer are etched to form at least A first groove, the first groove communicates with the cavity;
  • the second electrode layer and the piezoelectric layer are etched to form at least one second groove, and the projection of the first groove and the second groove on the plane where the piezoelectric layer is located forms a resonance effective Area.
  • the groove includes a first groove and A second groove
  • the second groove penetrates the second electrode and the piezoelectric layer
  • the first groove penetrates the first electrode and the piezoelectric layer and communicates with the cavity
  • the first groove and the second groove effectively block the propagation of the transverse wave in the invalid resonance region, improve the acoustic wave loss, and improve the quality factor of the film bulk acoustic wave resonator, thereby improving the performance of the device.
  • first electrode and the second electrode are patterned to overlap the first electrode resonance area and the second electrode resonance area with the effective resonance area, and the first electrode overlap area and the second electrode overlap area are in place.
  • the projections of the piezoelectric layer do not overlap, which effectively reduces the parasitic resonance, improves the acoustic wave loss, and further improves the quality factor of the film bulk acoustic wave resonator.
  • FIG. 1 is a schematic diagram of a cross-sectional structure of a thin-film bulk acoustic resonator with a groove structure in an embodiment of the present invention
  • FIG. 2A is a top view of a thin film bulk acoustic resonator with continuous first grooves and continuous second grooves in an embodiment of the present invention
  • 2B is a top view of another thin film bulk acoustic wave resonator with a plurality of discontinuous first grooves and a plurality of discontinuous second grooves in an embodiment of the present invention
  • 2C is a top view of a thin film bulk acoustic wave resonator with a multi-bridge structure electrode overlap area formed in an embodiment of the present invention
  • 2D is a top view of a thin film bulk acoustic resonator formed with mesh electrode overlap regions according to an embodiment of the present invention
  • Figure 3 is a schematic cross-sectional structure along the line AA ⁇ in Figure 2B;
  • FIG. 4 is a flowchart of a method for manufacturing a thin film bulk acoustic resonator according to an embodiment of the present invention
  • 5 to 13 are schematic structural diagrams corresponding to the corresponding steps of the method for manufacturing a thin-film bulk acoustic resonator provided by this embodiment;
  • the invention provides a thin-film bulk acoustic wave resonator, a manufacturing method thereof, a filter, and a radio frequency communication system.
  • FIG. 1 is a schematic cross-sectional structure diagram of a thin film bulk acoustic resonator with a groove structure in an embodiment of the present invention.
  • a thin film bulk acoustic wave resonator as shown in FIG. 1, includes a substrate 10 and a support layer 11 provided on the substrate 10.
  • the support layer 11 is provided with a cavity 11a with an opening at the top; and is covered on the cavity 11a
  • the piezoelectric stack has at least two grooves.
  • the grooves include a first groove 12a and a second groove 12b.
  • the second groove 12b penetrates the second electrode 15 and the piezoelectric layer 14, and the first groove 12a penetrates the first groove 12a.
  • An electrode 13 and the piezoelectric layer 14 are in communication with the cavity 11a.
  • the film bulk acoustic resonator provided by the present invention is provided with at least one first groove and at least one second groove in the piezoelectric stack, and the projection of the first groove and the second groove on the plane where the piezoelectric layer is located.
  • the first groove and the second groove in the present invention effectively block the propagation of transverse waves in the invalid resonance area, improve the acoustic wave loss, and obtain the quality factor of the film bulk acoustic wave resonator. Improve, thereby improving device performance.
  • FIG. 2A is a top view of a thin film bulk acoustic resonator with continuous first grooves and continuous second grooves in an embodiment of the invention
  • FIG. 2B is another multiple discontinuous first grooves and a plurality of discontinuous first grooves in an embodiment of the invention.
  • FIG. 2C is a top view of a thin film bulk acoustic resonator with a multi-bridge structure electrode overlap area formed in an embodiment of the present invention.
  • FIG. 2D is an embodiment of the present invention The top view of the thin film bulk acoustic resonator with the mesh electrode overlap area formed
  • FIG. 3 is a schematic cross-sectional structure diagram along the AA' line in FIG. 2B.
  • the film bulk acoustic resonator of this embodiment includes:
  • the piezoelectric stack 120 covering the cavity 110a includes a first electrode 103, a piezoelectric layer 104, and a second electrode 105 that are sequentially disposed on the support layer 101.
  • the piezoelectric stack 120 includes a piezoelectric stack located above the center of the cavity 110a.
  • Two trenches are distributed at the junction of the effective resonance region 001 and the ineffective resonance region 002 to define the range of the effective resonance region 001.
  • the trenches include a first trench 120a and a second trench 120b, and the second trench 120b penetrates through the second trench.
  • the electrode layer 105' and the piezoelectric layer 104, and the first groove 120a penetrates the first electrode 103 and the piezoelectric layer 101 and communicates with the cavity 110a.
  • the first substrate 100 can be any suitable substrate known to those skilled in the art, for example, it can 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 many of these semiconductors Layer structure, 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 It can also be Double Side Polished Wafers (DSP), ceramic substrates such as alumina, quartz or glass substrates, etc.
  • DSP Double Side Polished Wafers
  • DSP Double Side Polished Wafer
  • the material of the first substrate 100 in this embodiment is a P-type high resistance single crystal silicon wafer with a ⁇ 100> crystal orientation.
  • the material of the support layer 101 may 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 support layer 101 is located on the first substrate 100, and the support layer 101 is provided with a cavity 110a, and the cavity 110a may be formed by etching the support layer 101 through an etching process.
  • the technology of the present invention is not limited to this.
  • the shape of the bottom surface of the cavity 110a is rectangular, but in other embodiments of the present invention, the shape of the bottom surface of the cavity 110a may also be a circle, an ellipse, or a polygon other than a rectangle, such as a pentagon. , Hexagons, etc.
  • the piezoelectric stack 120 includes a first electrode 103, a piezoelectric layer 104, and a second electrode 105.
  • the first electrode 103 is located on the support layer 101, and the second electrode 105 is disposed opposite to the first electrode 103.
  • the piezoelectric layer 104 is located between the first electrode 103 and the second electrode 105, and the overlapping area of the first electrode 103, the piezoelectric layer 104, and the second electrode 105 in the thickness direction is directly above the cavity 110a.
  • An etch stop layer 102 is also provided between the support layer 101 and the first electrode 103, and its material includes but is not limited to silicon nitride (Si3N4) and silicon oxynitride (SiON).
  • the etch stop layer 102 can be used to increase the structural stability of the finally manufactured thin film bulk acoustic wave resonator.
  • the etch stop layer 102 has a lower etching rate than the support layer 101 and can be used in the etching process.
  • the etching support layer 101 prevents over-etching during the process of forming the cavity 110a, and protects the surface of the first electrode 103 underneath from damage, thereby improving device performance and reliability.
  • the first electrode 103 includes an edge region 103a that is not covered by the piezoelectric layer 104 and the second electrode 105 to facilitate subsequent input/output of electrical signals.
  • the first trench 120a and the second trench 120b which may also be referred to as an air gap cavity (Air Trench), are provided in the piezoelectric stack 120.
  • the first trench 120a penetrates the first electrode 103 and the piezoelectric layer 104, and In communication with the cavity 110 a, the second groove 120 b penetrates the second electrode 105 and the piezoelectric layer 104.
  • the projection of the first groove 120a and the second groove 120b on the plane where the piezoelectric layer 104 is in a semi-circular shape or a semi-circular polygon, and the first groove 120a and the second groove 120b are
  • the projections on the plane where the piezoelectric layer 104 is located can be exactly or close to each other, that is, the projections of the first groove 120a and the second groove 120b on the plane where the piezoelectric layer 104 is located can form a completely closed ring or Close to a closed ring
  • the joint of the projections of the first groove 120a and the second groove 120b on the plane where the piezoelectric layer 104 is located includes: a first joint 150a and a second joint 105b.
  • the first groove 120a and the second groove 120b cooperate to block transverse waves on the periphery of the piezoelectric resonant layer 1042, that is, the projection of the first groove 120a and the second groove 120b on the plane where the piezoelectric layer 104 is located.
  • the area where the formed pattern (circular or polygonal) is located is the effective resonance area 001 of the film bulk acoustic wave resonator.
  • the first trench 120a and the second trench 120b are located at the periphery of the effective resonance region 001, and the projection size of the first trench 120a and the second trench 120b on the plane where the piezoelectric layer 104 is located can be a combination of the two
  • the ring is equally divided (the first groove 120a and the second groove 120b are separated on both sides of the effective resonance region 001 and all parts are completely opposite), or unevenly (the first groove 120a and the second groove 120b is located on both sides of the effective resonance zone 001 and only partially opposite).
  • the cross section of the first trench 120a and the second trench 120b along the line AA' in FIG. 2A is trapezoidal or trapezoidal, that is, the angle ⁇ between the first trench 120a and the plane where the second electrode 105 is located, and the second trench
  • the angle ⁇ between the side wall of 120b and the plane where the first electrode 103 is located is an obtuse angle, wherein preferably ⁇ and ⁇ are greater than 90 degrees and less than 160 degrees.
  • the figure (effective resonant region 001) enclosed by the projection of the first groove 120a and the second groove 120b on the plane where the piezoelectric layer 104 is located is exactly connected pentagons, and any polygon The sides are not parallel.
  • the figure composed of the projection on the plane can be a discontinuous close to closed pentagon.
  • the support layer 101 and the first substrate 100 are bonded together by means of thermocompression bonding or dry film bonding.
  • the first electrode 103 includes a first electrode overlapping area 1031 and a first electrode resonance area 1032.
  • the first electrode resonance area 1032 overlaps the effective resonance area 001, and the first electrode overlapping area 1031 is connected to the An electrode resonance region 1032 and the support layer 101.
  • the second electrode 105 includes a second electrode overlapping area 1051 and a second electrode resonance area 1052.
  • the second electrode resonance area 1052 overlaps the effective resonance area 001, and the second electrode overlapping area 1051 connects the second electrode resonance area 1052 and the cavity
  • the second electrode lap area 1051 and the first electrode lap area 1031 do not overlap on the upper part of the cavity 110a to avoid parasitic resonance in the upper part of the cavity 110a except for the effective resonance area 02.
  • the second electrode bonding area 1051 and the first electrode bonding area 1031 are patterned into a bridge structure with one end connected to only one edge of the resonator. It can be ensured that the second electrode overlap area 1051 and the first electrode overlap area 1031 do not overlap on the upper part of the cavity 110a, and the parasitic resonance of the invalid resonance area 002 above the cavity 110a is avoided.
  • At least one of the second electrode bonding region 1051 and the first electrode bonding region 1031 may also be patterned as a multi-bridge structure with one end connected to multiple edges of the resonator, Among them, it is preferable to pattern the first electrode overlap area 1031 into a multi-bridge structure, and the second electrode overlap area 1051 and the multi-bridge structure of the first electrode overlap area 1031 do not overlap above the cavity 10a, and the multi-bridge structure can be strengthened The support of the piezoelectric stack 120 increases the mechanical strength of the resonator.
  • the second electrode lap area 1051 and the first electrode lap area 1031 can also be patterned as a planar structure with one end connected to multiple edges of the resonator Moreover, the second electrode lap area 1051 and the first electrode lap area 1031 do not overlap above the cavity 10a, which can further increase the mechanical strength of the resonator.
  • the first electrode layer 103' can be etched to have a certain line width along the junction of the first trench 120a and the second trench 120b (the first junction 150a, the second junction 150b). An opening 106a and a second opening 106b.
  • the first opening 106a and the second opening 106b penetrate the first electrode layer 103' and respectively extend from the first junction 150a and the second junction 150b (connected to the second trench 120b) to the first Outside the boundary of an electrode layer, similarly, the same two openings (not shown) are also etched at the positions corresponding to the first opening 106a and the second opening 106b in the second electrode layer 150', so as to It is achieved that the second electrode overlap area 1051 and the first electrode overlap area 1031 do not overlap on the upper part of the cavity 110a, so as to avoid parasitic resonance in the invalid resonance area 002 above the cavity 110a.
  • first opening 106a and the second opening 106b may also penetrate through the first electrode layer 103', the piezoelectric layer 104, and the second electrode layer 105', which can achieve the same electrode separation effect to avoid the cavity 110a Parasitic resonance occurs in the upper invalid resonance region 002.
  • the piezoelectric layer 104 includes a piezoelectric mounting area 1041 and a piezoelectric resonant area 1042.
  • the piezoelectric resonant area 1042 is located between the first electrode resonant area 1032 and the second electrode resonant area 1052.
  • the area 001 overlaps, the piezoelectric mounting area 1041 is connected to the edge of the resonator, and the piezoelectric mounting area 1041 and the piezoelectric resonance area 1042 are completely separated by the first groove 120a and the second groove 120b; among them, the second groove 120b is located in the first groove 120a and 120b.
  • the first trench 120a is located below the second electrode overlap region 1051.
  • the piezoelectric mounting region 1041 and the piezoelectric resonance region 1042 can be The plurality of first trenches 120a and the plurality of second trenches 120b are connected at intervals.
  • the film bulk acoustic resonator further includes a signal input/output structure.
  • the signal input/output structure is a first pad 107a and a second pad 107b respectively connected to the first electrode 103 and the second electrode 105.
  • the first pad 107a is connected to the piezoelectric layer 104 and the second electrode.
  • the edge area 103a of the first electrode 103 covered by 105 is connected, and the second pad 107b is connected to the edge area 105a of the second electrode 105.
  • FIG. 3 Please refer to FIG. 3.
  • An embodiment of the present invention also provides a filter including at least one of the above-mentioned thin film bulk acoustic wave resonators in any of the 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.
  • FIG. 4 is a flowchart of a method for manufacturing a thin film bulk acoustic resonator provided by an embodiment of the present invention, including:
  • a second substrate 200 is provided, and a piezoelectric laminate structure is formed on the second substrate 200.
  • the piezoelectric laminate structure is composed of a second electrode layer 105', a piezoelectric layer, and The first electrode layer 103 ⁇ constitutes;
  • S02 forming a support layer on the first electrode layer 103', forming a cavity with an opening in the support layer to expose a part of the first electrode layer 103', etching the first electrode layer 103' and the piezoelectric layer to form at least one A groove, the first groove communicates with the cavity;
  • S03 Provide a first substrate, and bond the first substrate to the support layer to form a cavity at the opening;
  • S05 The second electrode layer 105' and the piezoelectric layer are etched to form at least one second groove, and the projection of the first groove and the second groove on the plane where the piezoelectric layer is located encloses the effective resonance area.
  • FIGS. 5 to 13 are structural schematic diagrams corresponding to the corresponding steps of the method for manufacturing a thin-film bulk acoustic wave resonator provided by this embodiment.
  • the thin-film bulk acoustic resonator provided in this embodiment will be described in detail below with reference to FIGS. 2A and 5 to 13 Method of making.
  • step S01 is performed to provide a second substrate 200, and a piezoelectric stack 120 is formed on the second substrate 200.
  • the electrical stack structure 120 includes a second electrode 105, a piezoelectric layer 104, and a first electrode 103, wherein the piezoelectric layer 104 is located between the first electrode 103 and the second electrode 105, and the first electrode 103 and the second electrode 105 Relative settings.
  • the first electrode 103 may be used as an input electrode or an output electrode that receives or provides an electrical signal such as a radio frequency (RF) signal.
  • RF radio frequency
  • the first electrode 103 when the second electrode 105 is used as an input electrode, the first electrode 103 can be used as an output electrode, and when the second electrode 105 is used as an output electrode, the first electrode 103 can be used as an input electrode, and the piezoelectric layer 104
  • the electrical signal input through the first electrode 103 or the second electrode 105 is converted into a bulk acoustic wave.
  • the piezoelectric layer 104 converts electrical signals into bulk acoustic waves through physical vibration.
  • An isolation layer (not shown in FIG. 6) is also formed between the second substrate 200 and the piezoelectric stack 120 (the second electrode 105).
  • the isolation layer can be used as a protective layer of the second substrate 200 to avoid the influence of the piezoelectric stack 120 of the thin film bulk acoustic resonator formed later on the second substrate 200.
  • the isolation layer can be etched In this way, the second substrate 200 is separated from the piezoelectric stack 120 formed subsequently, which helps to quickly peel off the second substrate 200 and improve the manufacturing efficiency of the process.
  • the material of the isolation layer includes but is not limited to at least one of silicon dioxide (SiO2), silicon nitride (Si3N4), aluminum oxide (Al2O3), and aluminum nitride (AlN).
  • the isolation layer can be formed by chemical vapor deposition, magnetron sputtering, or evaporation.
  • the second substrate 200 is monocrystalline silicon, for example, a P-type high resistance monocrystalline silicon wafer with a ⁇ 100> crystal orientation, and the material of the isolation layer is silicon dioxide (SiO2).
  • the second electrode 105 and the first electrode 103 can use any suitable conductive material or semiconductor material well known to those skilled in the art, where the conductive material can be a metal material with conductive properties, for example, made of molybdenum (Mo), aluminum (Al ), copper (Cu), tungsten (W), tantalum (Ta), platinum (Pt), ruthenium (Ru), rhodium (Rh), iridium (Ir), chromium (Cr), titanium (Ti), gold (Au) ), osmium (Os), rhenium (Re), palladium (Pd) and other metals or a laminate of the above metals.
  • Mo molybdenum
  • Al aluminum
  • Cu copper
  • tantalum (Ta) platinum
  • Pt ruthenium
  • Ru rhodium
  • Ir iridium
  • Cr chromium
  • Ti titanium
  • Au gold
  • Au osmium
  • Re palla
  • the semiconductor material is for example Si, Ge, SiGe, SiC, SiGeC, etc.
  • the second electrode layer 105' and the first electrode layer 103' can be formed by physical vapor deposition or chemical vapor deposition methods such as magnetron sputtering, evaporation, etc.
  • the piezoelectric layer 104 may also be referred to as a piezoelectric resonance layer or a piezoelectric resonance region.
  • the material of the piezoelectric layer 104 can be aluminum nitride (AlN), zinc oxide (ZnO), lead zirconate titanate (PZT), lithium niobate (LiNbO3), quartz (Quartz), potassium niobate (KNbO3) or tantalic acid Piezoelectric materials with wurtzite crystal structure such as lithium (LiTaO3) and their combinations.
  • AlN aluminum nitride
  • the piezoelectric layer 104 may further include a rare earth metal, such as at least one of scandium (Sc), erbium (Er), yttrium (Y), and lanthanum (La).
  • the piezoelectric layer 104 may further include a transition metal, such as at least one of zirconium (Zr), titanium (Ti), manganese (Mn), and hafnium (Hf).
  • the piezoelectric layer 104 can be deposited and formed by any suitable method known to those skilled in the art such as chemical vapor deposition, physical vapor deposition, or atomic layer deposition.
  • the second electrode layer 105' and the first electrode layer 103' are made of metal molybdenum (Mo)
  • the piezoelectric layer 104 is made of aluminum nitride (AlN).
  • the shapes of the second electrode layer 105', the piezoelectric layer 104 and the first electrode layer 103' may be the same or different.
  • the shapes and areas of the second electrode layer 105', the piezoelectric layer 104 and the first electrode layer 103' are the same, and all are polygonal, such as square.
  • a seed layer (not shown in FIG. 6) may be formed on the isolation layer.
  • the seed layer is formed between the isolation layer and the second electrode layer 105'.
  • the crystal orientation of the second electrode layer 105' (the piezoelectric layer 104 and the first electrode layer 103') is oriented, which facilitates the growth of the subsequently formed piezoelectric laminate structure along a specific crystal direction and ensures the uniformity of the piezoelectric layer.
  • the material of the seed layer can be aluminum nitride (AlN).
  • AlN aluminum nitride
  • the seed layer can also be formed of a metal or dielectric material having a hexagonal close packed (HCP) structure.
  • the seed layer may also be formed of metal titanium (Ti).
  • step S02 is performed to form a support layer 101 on the first electrode layer 103', and an opening 110a' is formed in the support layer 101 to expose a portion of the first electrode layer 103', and the first electrode is etched
  • the layer 103' and the piezoelectric layer 104 form a first trench 120a, and the first trench is in communication with the opening 110a'.
  • a support layer 101 can be formed on the first electrode layer 103' by a chemical deposition method.
  • the material of the support layer 101 is, for example, silicon dioxide (SiO2) or silicon nitride (Si3N4).
  • the material of the support layer 101 in this embodiment is silicon dioxide (SiO2).
  • the etching process may be a wet etching or a dry etching process, which is more A dry etching process is preferably used. Dry etching includes but is not limited to reactive ion etching (RIE), ion beam etching, plasma etching or laser cutting.
  • RIE reactive ion etching
  • ion beam etching plasma etching or laser cutting.
  • the depth and shape of the opening 110a' depend on the depth and shape of the cavity required for the bulk acoustic wave resonator to be manufactured, that is, the depth of the opening 110a' can be determined by forming the thickness of the support layer 101.
  • the shape of the bottom surface of the opening 110a' can be a rectangle or a polygon other than a rectangle, such as a pentagon, a hexagon, an octagon, etc., and can also be a circle or an ellipse.
  • the longitudinal cross-sectional shape of the opening 110a' can also be a spherical cap with a wide upper and a narrow bottom, that is, its longitudinal cross-section is U-shaped.
  • an etch stop layer 102 is also formed on the first electrode layer 103', and its material includes but is not limited to silicon nitride (Si3N4) and silicon oxynitride (SiON).
  • the etch stop layer 102 has a lower etch rate than the support layer 101 formed subsequently, which can prevent over-etching when the support layer 101 is subsequently etched to form the opening 110a' and protect the first electrode layer located thereunder The 103 ⁇ surface is not damaged.
  • the first electrode layer 103' and the piezoelectric layer 104 are etched to form a first trench 120a in the opening 110a'.
  • the sidewall of the first trench 120a may be inclined or vertical.
  • the sidewall of the first trench 120a and the plane where the second electrode 105 is located form an obtuse angle (the shape of the longitudinal section (the section along the thickness direction of the substrate) of the first trench 120a is an inverted trapezoid).
  • the projection of the first groove 120a on the plane where the piezoelectric layer 104 is located is a half-ring or a half-ring-like polygon. In other embodiments, referring to FIG.
  • a plurality of discontinuous first grooves 120a may also be formed, so that the projection of the plurality of first grooves 120a on the plane where the piezoelectric layer 104 is located is a discontinuous semicircular ring.
  • the etching process for etching the first trench is a dry etching process. Dry etching includes, but is not limited to, inductively coupled plasma (ICP) etching, reactive ion etching (RIE), and ion beam etching. , Plasma etching or laser cutting, the angle ⁇ between the sidewall of the first trench 120a etched and the plane where the second electrode 105 is located is an obtuse angle, preferably 90 ⁇ ⁇ ⁇ 160.
  • the first electrode 103 is patterned on the first electrode layer 103'. Specifically, the surface of the first electrode layer 103' is coated with photoresist to form a photoresist layer, and the photoresist layer is patterned by photolithography through a first mask with a preset first electrode pattern, and the patterned The photoresist layer is used as a mask, and then the first electrode layer 103' is etched by a dry etching process.
  • the first electrode 103 formed by the etching includes a first electrode lap area 1031 and a first electrode resonance area 1032.
  • the electrode resonance region 1032 overlaps the effective resonance region 001, and the formed first electrode overlap region 1031 connects the first electrode resonance region 1031 and the support layer surrounding the cavity.
  • the first electrode overlap region 1031 of FIG. 2C may also be a planar structure connecting multiple sides of the support layer 101 or multiple bridge structures. It should be noted that in the process of patterning the first electrode, all areas of the first electrode layer 103' except for the first electrode overlap region 1031 and the first electrode resonance region 1032 can be etched away, or Only the first electrode 103 is electrically isolated from other regions in the first electrode layer 103 ⁇ .
  • the boundary of the first electrode 103 pattern defined in the first electrode layer 103 ⁇ can be etched (the first trench 120a defines Area outside the boundary of the first electrode), penetrate the first electrode layer 103', and etch a gap with a certain line width along the boundary of the first electrode 103 pattern, and finally remove the first electrode 103 from the first electrode layer 103' Is completely separated from each other, and other regions in the first electrode layer 103' can still be retained to achieve electrical separation.
  • step S03 is performed to bond the first substrate 100 and the support layer 101, and the first substrate 100 and the first electrode 103 form a cavity 110a at the opening 110a' of the support layer 101.
  • the first 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), Silicon carbon (SiC), silicon germanium (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 It is Double Side Polishe
  • the bonding of the first substrate 100 and the support layer 101 can be achieved by thermocompression bonding or dry film bonding. After the bonding process is completed, the above-mentioned film bulk acoustic resonator after bonding is turned over for subsequent steps.
  • the method for forming the first trench 120a and the cavity 110a further includes:
  • a first substrate 100 is provided, a support layer 101 is formed on the first substrate 100, a part of the first substrate 100 is exposed by etching the support layer 101, and an opening 110a ⁇ is formed in the support layer 101; the first electrode 103 is etched
  • the first trench 120a is formed with the piezoelectric layer 104; the support layer 101 formed with the opening 110a' and the piezoelectric stack 120 formed with the first trench 120a are bonded to form a cavity 110a.
  • step S04 is performed to remove the second substrate 200.
  • the second substrate 200 is peeled off by etching the isolation layer.
  • other methods may be used to remove the second substrate 200, such as etching or mechanical grinding.
  • step S05 is performed to etch the second electrode layer 105' and the piezoelectric layer 104 to form a second trench 120b.
  • the first trench 120a and the second trench 120b are in the piezoelectric layer 104
  • the projection on the plane where it is located encloses a closed or nearly closed figure.
  • the second electrode 105 and the piezoelectric layer 104 are etched to form the second trench 120b, as shown in FIG. 13.
  • the sidewalls of the second trench 120b may be inclined or vertical.
  • the sidewall of the second trench 120b and the plane of the first electrode layer 103' form an obtuse angle (the shape of the longitudinal section (the section along the thickness direction of the substrate) of the second trench 120b is an inverted trapezoid).
  • the projection of the second groove 120b on the plane where the piezoelectric layer 104 is located is a semi-annular or a semi-annular polygon. In other embodiments, referring to FIG.
  • a plurality of discontinuous second grooves 120a may also be formed, so that the projection of the plurality of second grooves 120a on the plane where the piezoelectric layer 104 is located forms a discontinuous semi-annular ring.
  • the etching process for etching the second trench is a dry etching process, and dry etching includes but not limited to reactive ion etching (RIE), ion beam etching, plasma etching or laser cutting,
  • RIE reactive ion etching
  • ion beam etching plasma etching or laser cutting
  • the angle ⁇ between the sidewall of the etched second trench 120a and the plane where the first electrode 103 is located is an obtuse angle, preferably 90 ⁇ 160.
  • the second electrode 105 is patterned on the second electrode layer 105'. Specifically, photoresist is applied to the surface of the second electrode layer 105' to form a photoresist layer, and the photoresist layer is patterned by photolithography through a first mask with a preset first electrode pattern, and the patterned The photoresist layer is used as a mask, and then the second electrode layer 105' is etched by a dry etching process.
  • the second electrode 105 formed by the etching includes a second electrode lap area 1051 and a second electrode resonance area 1052.
  • the electrode resonance region 1052 overlaps the effective resonance region 001, and the formed second electrode lap area 1051 connects the second electrode resonance region 1052 and the piezoelectric laminate around the cavity.
  • the second electrode lap area Area 1051 is a bridge structure.
  • the second electrode overlapping area 1051 may also be a planar structure or multiple bridge structures with one end connected to the second electrode overlapping area 1051 and the other end connected to the edge of the piezoelectric laminate on the periphery of the cavity.
  • the second electrode overlap area 1051 and the first electrode overlap area 1031 do not overlap above the cavity, so as to reduce the parasitic resonance of the non-resonant effective area (invalid resonance area 002) above the cavity.
  • all areas of the second electrode layer 105' except for the second electrode overlap region 1051 and the second electrode resonance region 1052 can be etched away, or Only the second electrode 105 is electrically isolated from other areas in the second electrode layer 105', for example, by etching the boundary of the second electrode 105 pattern defined in the second electrode layer 105' (defined by the second trench 120b) Area outside the boundary of the second electrode), and penetrate the second electrode layer 105', etch a gap with a certain line width along the boundary of the second electrode 103 pattern, and finally remove the second electrode 105 from the second electrode layer 105' After being completely separated, other areas in the second electrode layer 105' can still be retained, realizing electrical separation.
  • the cross-sections of the first groove 120a and the second groove 120b along the line AA' in FIG. 2A are trapezoidal or trapezoidal-like (that is, ⁇ and ⁇ are obtuse angles).
  • the first groove 120a and the second groove The figure (effective resonance region 001) enclosed by the projection of the groove 120b on the plane where the piezoelectric layer 104 is located is exactly connected pentagons, and the polygon does not include any pair of relatively parallel straight segments.
  • the pattern formed by the projection of the first groove 120a and the second groove 120b on the plane where the piezoelectric layer 104 is located may also have a gap at the two junctions (the first junction gap 150a ⁇ and the second junction with a gap of 150b ⁇ ) close to a closed pentagon, as shown in Figure 2B.
  • the second pad 107b may be formed on the edge portion 105a.
  • part of the second electrode 105 (edge portion 105a) and the piezoelectric layer 104 may be etched to expose the edge of the first electrode 103 side.
  • the portion 103a is convenient for signal input/output of the first electrode 103.
  • a first pad 107a may be formed on the edge portion 103a.
  • the film bulk acoustic resonator, its manufacturing method, filter, and radio frequency communication system provided by the present invention.
  • the film bulk acoustic wave resonator provided by the present invention is provided with a first groove and a second groove in the piezoelectric stack, and the projection of the first groove and the second groove on the plane where the piezoelectric layer is located forms the film bulk acoustic wave The effective resonance area of the resonator.
  • the first groove and the second groove effectively block the propagation of the transverse wave in the ineffective resonance area, improve the acoustic wave loss, and increase the quality factor of the film bulk acoustic wave resonator, thereby increasing Device performance.
  • the patterned first electrode overlap area and the second electrode overlap area do not overlap above the cavity, effectively avoiding the parasitic resonance of the ineffective resonant area of the piezoelectric laminate, and further improving the quality factor of the film bulk acoustic wave resonator .

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Abstract

本发明提供一种薄膜体声波谐振器及其制造方法和滤波器、射频通信***。包括：第一衬底及设置第一衬底上的支撑层，支撑层中设置有顶部开口的空腔；盖设于空腔上的压电叠层，至少两个沟槽，分布于有效谐振区和无效谐振区的交界处以界定有效谐振区的范围，沟槽包括第一沟槽和第二沟槽，第二沟槽贯穿第二电极和压电层，第一沟槽贯穿第一电极和压电层并与空腔连通。本发明提供的薄膜体声波谐振器在压电叠层中设置至少一个第一沟槽和至少一个第二沟槽，第一沟槽和第二沟槽有效阻断了横波在无效谐振区的传播。进一步的，电极图形化有效减少了寄生谐振，改善了声波损耗，进一步提高薄膜体声波谐振器的品质因子。

Description

薄膜体声波谐振器及其制造方法和滤波器、射频通信*** 技术领域
本发明涉及半导体器件制造领域，尤其涉及一种薄膜体声波谐振器及其制作方法和滤波器、射频通信***。
 背景技术
自模拟射频通讯技术在上世纪90代初被开发以来，射频前端模块已经逐渐成为通讯设备的核心组件。在所有射频前端模块中，滤波器已成为增长势头最猛、发展前景最大的部件。随着无线通讯技术的高速发展，5G通讯协议日渐成熟，市场对射频滤波器的各方面性能也提出了更为严格的标准。滤波器的性能由组成滤波器的谐振器单元决定。在现有的滤波器中，薄膜体声波谐振器(FBAR)因其体积小、***损耗低、带外抑制大、品质因数高、工作频率高、功率容量大以及抗静电冲击能力良好等特点，成为最适合5G应用的滤波器之一。
通常，薄膜体声波谐振器包括两个薄膜电极，并且两个薄膜电极之间设有压电薄膜层，其工作原理为利用压电薄膜层在交变电场下产生振动，该振动激励出沿压电薄膜层厚度方向传播的体声波，此声波传至上下电极与空气交界面被反射回来，进而在薄膜内部来回反射，形成震荡。当声波在压电薄膜层中传播正好是半波长的奇数倍时，形成驻波震荡。
 技术问题
但是，目前制作出的空腔型薄膜体声波谐振器，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***的需求。
 技术解决方案
本发明的目的在于提供一种薄膜体声波谐振器及其制造方法和滤波器、射频通信***，能够提高薄膜体声波谐振器的品质因子，进而提高器件性能。
为了实现上述目的，本发明提供一种薄膜体声波谐振器，包括：
第一衬底及设置于所述第一衬底上的支撑层，所述支撑层中设置有顶部开口的空腔；
盖设于空腔上的压电叠层，包括依次设置在所述支撑层上的第一电极、压电层和第二电极，所述压电叠层包括位于所述空腔中央上方的有效谐振区和包围所述效谐振区的无效谐振区；
至少两个沟槽，分布于所述有效谐振区和无效谐振区的交界处以界定有效谐振区的范围，所述沟槽包括第一沟槽和第二沟槽，所述第二沟槽贯穿所述第二电极和所述压电层，所述第一沟槽贯穿所述第一电极和所述压电层并与所述空腔连通。
本发明还提供一种滤波器，包括至少一个所述的薄膜体声波谐振器。
本发明还提供一种滤波器一种射频通信***，包括至少一个所述的滤波器。
本发明还提供一种滤波器一种薄膜体声波谐振器的制造方法，包括：提供第二衬底，在所述第二衬底上形成压电叠层，所述压电叠层包括依次形成在所述第二衬底上的第二电极层、压电层及第一电极层；
在所述第一电极层上形成支撑层，在所述支撑层中形成具有开口的空腔以暴露部分所述第一电极层，刻蚀所述第一电极层和所述压电层形成至少一个第一沟槽，所述第一沟槽与所述空腔连通；
提供第一衬底，将所述第一衬底与所述支撑层键合以封闭所述空腔的开口；
去除所述第二衬底；
刻蚀所述第二电极层和所述压电层形成至少一个第二沟槽，所述第一沟槽和所述第二沟槽在所述压电层所在平面上的投影围成谐振有效区。
 有益效果
本发明的有益效果为：
本发明提供的薄膜体声波谐振器中，通过设置至少两个沟槽，分布于所述有效谐振区和无效谐振区的交界处以界定有效谐振区的范围，所述沟槽包括第一沟槽和第二沟槽，所述第二沟槽贯穿所述第二电极和所述压电层，所述第一沟槽贯穿所述第一电极和所述压电层并与所述空腔连通，所述第一沟槽和第二沟槽有效阻断了横波在无效谐振区的传播，改善了声波损耗，使薄膜体声波谐振器的品质因子得到提高，进而提高器件性能。
进一步的，通过图形化的第一电极和第二电极使第一电极谐振区和第二电极谐振区与有效谐振区重叠，并使第一电极搭接区、和第二电极搭接区在所述压电层的投影不重叠，有效减少了寄生谐振，改善了声波损耗，进一步提高薄膜体声波谐振器的品质因子。
 附图说明
为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1为本发明一实施例中一种带有沟槽结构的薄膜体声波谐振器的剖面结构示意图；
图2A为本发明一实施例中一种连续第一沟槽与连续第二沟槽薄膜体声波谐振器俯视图；
图2B为本发明一实施例中另一种多个不连续第一沟槽与多个不连续第二沟槽的薄膜体声波谐振器俯视图；
图2C为本发明一实施例中形成有多桥结构电极搭接区的薄膜体声波谐振器俯视图；
图2D为本发明一实施例形成有网状电极搭接区的薄膜体声波谐振器俯视图；
图3是沿图2B中的AA´线的剖面结构示意图；
图4为本发明一实施例提供的一种薄膜体声波谐振器的制作方法的流程图；
图5至13为本实施例提供的一种薄膜体声波谐振器的制作方法的相应步骤对应的结构示意图；
附图标记说明：
图1中：
10-衬底；11-支撑层；11a -空腔；12a-第一沟槽；12b-第二沟槽；13-第一电极；14-压电层；15-第二电极；
图2A~13中：
100-第一衬底；200-第二衬底；120-压电叠层； 101-支撑层；110a´-开口；110a -空腔；120a-第一沟槽；120b-第二沟槽；103-第一电极；103´-第一电极层；103a-第一电极边缘区域；1031-第一电极搭接区；1032-第一电极谐振区；104-压电层；1041-压电搭载区；1042-压电谐振区；105-第二电极；105´-第二电极层；105a-第二电极边缘区域；1051-第二电极搭接区；1052-第二电极谐振区；106a-第一开口；106b-第二开口；107a-第一焊盘；107b-第二焊盘；150a-第一衔接处；150b-第二衔接处；150a´-第一衔接处间隙；150b´-第二衔接处间隙；000-谐振区；001-有效谐振区；002-无效谐振区。
 本发明的实施方式
本发明提供一种薄膜体声波谐振器及其制造方法和滤波器、射频通信***。
图1为本发明一实施例中一种带有沟槽结构的薄膜体声波谐振器的剖面结构示意图。一种薄膜体声波谐振器，如图1所示，包括：衬底10及设置衬底10上的支撑层11，支撑层11中设置有顶部开口的空腔11a；盖设于空腔11a上的压电叠层，至少两个沟槽，沟槽包括第一沟槽12a和第二沟槽12b，第二沟槽12b贯穿第二电极15和压电层14，第一沟槽12a贯穿第一电极13和压电层14并与空腔11a连通。
本发明提供的薄膜体声波谐振器在压电叠层中设置至少一个第一沟槽和至少一个第二沟槽，第一沟槽和第二沟槽在压电层所在的平面上的投影围成薄膜体声波谐振器的有效谐振区，本发明中第一沟槽和第二沟槽有效阻断了横波在无效谐振区的传播，改善了声波损耗，使薄膜体声波谐振器的品质因子得到提高，进而提高器件性能。
以下结合附图和具体实施例对本发明的薄膜体声波谐振器、薄膜体声波谐振器的制作方法作进一步详细说明。根据下面的说明和附图，本发明的优点和特征将更清楚，然而，需说明的是，本发明技术方案的构思可按照多种不同的形式实施，并不局限于在此阐述的特定实施例。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。
在说明书和权利要求书中的术语“第一”“第二”等用于在类似要素之间进行区分，且未必是用于描述特定次序或时间顺序。要理解，在适当情况下，如此使用的这些术语可替换，例如可使得本文所述的本发明实施例能够以不同于本文所述的或所示的其他顺序来操作。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。若某附图中的构件与其他附图中的构件相同，虽然在所有附图中都可轻易辨认出这些构件，但为了使附图的说明更为清楚，本说明书不会将所有相同构件的标号标于每一图中。
图2A为本发明一实施例中一种连续第一沟槽与连续第二沟槽薄膜体声波谐振器俯视图，图2B为本发明一实施例中另一种多个不连续第一沟槽与多个不连续第二沟槽的薄膜体声波谐振器俯视图，图2C为本发明一实施例中形成有多桥结构电极搭接区的薄膜体声波谐振器俯视图，图2D为本发明一实施例形成有网状电极搭接区的薄膜体声波谐振器俯视图，图3是沿图2B中的AA´线的剖面结构示意图。
请参考图2A和图3，本实施例的薄膜体声波谐振器包括：
第一衬底100及设置第一衬底上的支撑层101，支撑层101中设置有顶部开口的空腔110a；
盖设于空腔110a上的压电叠层120，包括依次设置在支撑层101上的第一电极103、压电层104和第二电极105，压电叠层120包括位于空腔110a中央上方的有效谐振区001和包围所述效谐振区001的无效谐振区002；；
两个沟槽，分布于有效谐振区001和无效谐振区002的交界处以界定有效谐振区001的范围，沟槽包括第一沟槽120a和第二沟槽120b，第二沟槽120b贯穿第二电极层105´和压电层104，第一沟槽120a贯穿第一电极103和压电层101并与空腔110a连通。
其中，第一衬底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。
本实施例中第一衬底100的材料为<100>晶向的P型高阻单晶硅片。
支撑层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。
支撑层101位于第一衬底100上，且支撑层101中设置有空腔110a，空腔110a可以通过刻蚀工艺刻蚀支撑层101形成。但本发明的技术不仅仅限定于此。本实施例中，空腔110a的底面的形状为矩形，但在本发明的其他实施例中，空腔110a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。
压电叠层120包括第一电极103、压电层104和第二电极105，第一电极103位于支撑层101上，第二电极105与第一电极103相对设置。压电层104位于第一电极103和第二电极105之间，第一电极103、压电层104和第二电极105在厚度方向上的重叠区域在空腔110a的正上方。
支撑层101与第一电极103之间还设置有刻蚀停止层102，其材质包括但不限于氮化硅（Si3N4）和氮氧化硅（SiON）。
刻蚀停止层102一方面可以用于增加最终制造的薄膜体声波谐振器的结构稳定性，另一方面，刻蚀停止层102与支撑层101相比具有较低的刻蚀速率，可以在刻蚀支撑层101形成空腔110a的过程中防止过刻蚀，保护位于其下的第一电极103的表面不受到损伤，从而提高器件性能与可靠性。需要说明的是，第一电极103包括未被压电层104和第二电极105覆盖的边缘区域103a，以便于后续电信号的输入/输出。
第一沟槽120a和第二沟槽120b，也可称作气隙腔（Air Trench），设置在压电叠层120中，第一沟槽120a贯穿第一电极103和压电层104，并与空腔110a连通，第二沟槽120b贯穿第二电极105和压电层104。
请参考图2A，第一沟槽120a和第二沟槽120b在压电层104所在的平面上的投影为半环形或类似半环形的多边形，且第一沟槽120a和第二沟槽120b在压电层104所在的平面上的投影可以正好相接或者接近相接，即第一沟槽120a和第二沟槽120b在压电层104所在的平面上的投影可以组成一个完全封闭的环或者接近封闭的环，其中，第一沟槽120a和第二沟槽120b在压电层104所在的平面上的投影的衔接处包括：第一衔接处150a和第二衔接处105b。第一沟槽120a和第二沟槽120b配合，可以对压电谐振层1042的周边进行横波阻挡，即第一沟槽120a和第二沟槽120b在压电层104所在的平面上的投影围成的图形（圆形或多边形）所在的区域为薄膜体声波谐振器的有效谐振区001。第一沟槽120a和第二沟槽120b位于有效谐振区001的***，第一沟槽120a和第二沟槽120b在压电层104所在的平面上的投影大小可以对两者组合而成的环均分（此时第一沟槽120a和第二沟槽120b分居有效谐振区001两侧且所有部分均完全相对），也可以不均分（此时第一沟槽120a和第二沟槽120b分居有效谐振区001两侧且仅有部分相对）。
另外，第一沟槽120a和第二沟槽120b沿图2A中AA´线的截面为梯形或类梯形，即第一沟槽120a与第二电极105所在平面的夹角α、第二沟槽120b的侧壁与第一电极103所在平面的夹角β为钝角，其中优选α、β大于90度小于160度。
本实施例中，第一沟槽120a和第二沟槽120b在压电层104所在的平面上的投影围成的图形（有效谐振区001）为正好相接的五边形，且多边形的任意两边不平行。在其他实施例中，如图2B所示，第一沟槽120a和第二沟槽120b也可以是多个，多个第一沟槽120a和多个第二沟槽120b在压电层104所在的平面上的投影组成的图形可以是不连续接近闭合的五边形。
在本实施例中，支撑层101和第一衬底100通过热压键合或干膜键合的方式键合在一起。
在压电叠层120中，第一电极103包括第一电极搭接区1031和第一电极谐振区1032，第一电极谐振区1032与有效谐振区001重叠，第一电极搭接区1031连接第一电极谐振区1032和支撑层101。第二电极105包括第二电极搭接区1051和第二电极谐振区1052，第二电极谐振区1052与有效谐振区001重叠，第二电极搭接区1051连接第二电极谐振区1052和空腔的***的压电叠层，其中第二电极搭接区1051与第一电极搭接区1031在空腔110a上部没有重叠，以避免空腔110a上部除去有效谐振区02以外的区域发生寄生谐振。在本实施例和另一个实施例中，请参考图2A和图2B，第二电极搭接区1051与第一电极搭接区1031被图形化为一端只与谐振器一个边缘连接的桥结构，能够保证第二电极搭接区1051与第一电极搭接区1031在空腔110a上部没有重叠，避免空腔110a上方的无效谐振区002发生寄生谐振。
在其他实施例中，如图2C所示，第二电极搭接区1051、第一电极搭接区1031中的至少一个也可以被图形化为一端与谐振器多个边缘连接的多桥结构，其中优选将第一电极搭接区1031图形化为多桥结构，且第二电极搭接区1051、第一电极搭接区1031的多桥结构在空腔10a上方不重叠，多桥结构能够加强对压电叠层120的支撑，增加谐振器的机械强度。
进一步的，在另一个实施例中，参考图2D，第二电极搭接区1051、第一电极搭接区1031中的至少一个也可以被图形化为一端与谐振器多个边缘连接的平面结构，且第二电极搭接区1051、第一电极搭接区1031在空腔10a上方不重叠，能够进一步增加谐振器的机械强度。具体实施时，可以通过沿第一沟槽120a、第二沟槽120b交界处（第一衔接处150a、第二衔接处150b）分别对第一电极层103´刻蚀出具有一定线宽的第一开口106a和第二开口106b，第一开口106a和第二开口106b贯穿第一电极层103´并分别从第一衔接处150a、第二衔接处150b（连通第二沟槽120b）延伸至第一电极层的边界以外，同样的，在第二电极层150´中与第一开口106a和第二开口106b相对应的位置，也刻蚀相同的两个开口（未示出），以此能够实现第二电极搭接区1051与第一电极搭接区1031在空腔110a上部没有重叠，避免空腔110a上方的无效谐振区002发生寄生谐振。在其他实施例中，第一开口106a和第二开口106b也可以贯穿第一电极层103´、压电层104以及第二电极层105´，能够实现相同的电极分离效果，以避免空腔110a上方的无效谐振区002发生寄生谐振。
参考图2A和图3，压电层104包括压电搭载区1041和压电谐振区1042，压电谐振区1042位于第一电极谐振区1032与第二电极谐振区1052之间，即与有效谐振区001重叠，压电搭载区1041与谐振器边缘连接，压电搭载区1041和压电谐振区1042被第一沟槽120a、第二沟槽120b完全分离；其中，第二沟槽120b位于第一电极搭接区1031的上方，第一沟槽120a位于第二电极搭接区1051的下方。在其他实施例中，请参考图 2B、图2C，由于第一沟槽120a、第二沟槽120b为多个且不连续的沟槽，因此压电搭载区1041和压电谐振区1042能够在多个第一沟槽120a以及多个第二沟槽120b间隔处保持连接。
在本发明其他实施例中，薄膜体声波谐振器还包括：信号输入/输出结构。例如信号输入/输出结构为分别连接第一电极103和第二电极105的第一焊盘107a和第二焊盘107b，具体的，第一焊盘107a与未被压电层104和第二电极105覆盖的第一电极103的边缘区域103a连接，第二焊盘107b与第二电极105的边缘区域105a连接，请参考图3。
本发明一实施例还提供一种滤波器，包括至少一个上述的任意本发明实施例的薄膜体声波谐振器。
本发明一实施例还提供一种射频通信***，包括至少一个本发明一实施例的滤波器。
本发明一实施例还提供一种薄膜体声波谐振器的制造方法，请参考图4，图4为本发明一实施例提供的一种薄膜体声波谐振器的制作方法的流程图，包括：
S01：提供第二衬底200，在第二衬底200上形成压电叠层结构，压电叠层结构由依次形成在第二衬底200上的第二电极层105´、压电层及第一电极层103´构成；
S02：在第一电极层103´上形成支撑层，在支撑层中形成具有开口的空腔以暴露部分第一电极层103´，刻蚀第一电极层103´和压电层形成至少一个第一沟槽，第一沟槽与空腔连通；
S03：提供第一衬底，将第一衬底与支撑层键合以在开口处形成空腔；
S04：去除第二衬底200；
S05：刻蚀第二电极层105´和压电层形成至少一个第二沟槽，第一沟槽和第二沟槽在压电层所在平面上的投影围成谐振有效区。
图5至13为本实施例提供的一种薄膜体声波谐振器的制作方法的相应步骤对应的结构示意图，以下将参考图2A和图5至13详细说明本实施例提供的薄膜体声波谐振器的制作方法。
参考图5和图6所示，执行步骤S01，提供第二衬底200，在第二衬底200上形成压电叠层120。电叠层结构120包括第二电极105、压电层104和第一电极103，其中，压电层104位于第一电极103和第二电极105之间，且第一电极103和第二电极105相对设置。第一电极103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，当第二电极105用作输入电极时，第一电极103可用作输出电极，并且当第二电极105用作输出电极时，第一电极103可用作输入电极，压电层104将通过第一电极103或第二电极105上输入的电信号转换为体声波。例如，压电层104通过物理振动将电信号转换为体声波。
第二衬底200与压电叠层120（第二电极105）之间还形成有隔离层（图6中未示出）。隔离层可以作为第二衬底200的保护层，避免后续形成的薄膜体声波谐振器的压电叠层120对第二衬底200的影响，同时，在后续剥离工艺中，可以通过腐蚀隔离层的方式，使第二衬底200与后续形成的压电叠层120分离，有助于快速剥离第二衬底200，提高工艺制作效率。隔离层的材质包括但不限于二氧化硅(SiO2)、氮化硅(Si3N4)、氧化铝（Al2O3）和氮化铝（AlN）中的至少一种。隔离层可通过化学气相沉积、磁控溅射或蒸镀等方式形成。本实施例中第二衬底200为单晶硅，例如可以为<100>晶向的P型高阻单晶硅片，隔离层的材质为二氧化硅(SiO2)。
第二电极105和第一电极103可以使用本领域技术人员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，由钼（Mo）、铝（Al）、铜（Cu）、钨（W）、钽（Ta）、铂（Pt）、钌（Ru）、铑（Rh）、铱（Ir）、铬（Cr）、钛（Ti）、金(Au)、锇(Os)、铼(Re)、钯(Pd)等金属中一种制成或由上述金属形成的叠层制成，半导体材料例如是Si、Ge、SiGe、SiC、SiGeC等。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第二电极层105´和第一电极层103´。压电层104也可称为压电谐振层或压电谐振区。压电层104的材料可以使用氮化铝(AlN)、氧化锌(ZnO)、锆钛酸铅(PZT)、铌酸锂(LiNbO3)、石英(Quartz)、铌酸钾(KNbO3)或钽酸锂(LiTaO3)等具有纤锌矿型结晶结构的压电材料及它们的组合。当压电层104包括氮化铝(AlN)时，压电层104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，当压电层104包括氮化铝(AlN)时，压电层104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。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层104。优选的，本实施例中，第二电极层105´和第一电极层103´由金属钼（Mo）制成，压电层104由氮化铝（AlN）制成。
第二电极层105´、压电层104和第一电极层103´的形状可以相同也可以不相同。本实施例中，第二电极层105´、压电层104和第一电极层103´的形状和面积相同，均为多边形例如方形。
在形成第二电极层105´之前，可以在隔离层上形成种子层（图6中未示出），种子层形成在隔离层和第二电极层105´之间，种子层对后续形成的第二电极层105´（压电层104和第一电极层103´）的晶向具有导向性，便于后续形成的压电叠层结构沿特定的晶向生长，保证压电层的均匀性。种子层的材质可以为氮化铝(AlN)，除了AlN以外，种子层还可使用具有密排六方(HCP)结构的金属或介电材料形成。例如，种子层也可以由金属钛（Ti）形成。
参考图7至图9所示，执行步骤S02，在第一电极层103´上形成支撑层101，在支撑层101中形成开口110a´以暴露部分第一电极层103´，刻蚀第一电极层103´和压电层104形成第一沟槽120a，第一沟槽与开口110a´连通。具体的，首先，可以通过化学沉积的方法在第一电极层103´上形成支撑层101，如图7所示，支撑层101的材质例如为二氧化硅（SiO2）、氮化硅(Si3N4)、氧化铝（Al2O3）和氮化铝（AlN）的一种或几种组合。本实施例中支撑层101的材质为二氧化硅（SiO2）。然后，通过刻蚀工艺刻蚀支撑层101形成开口110a´以暴露部分第一电极层103´，如图8所示，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。开口110a´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，即可以通过形成支撑层101的厚度来确定开口110a´的深度。开口110a´底面的形状可以为矩形或是矩形以外的多边形，例如五边形、六边形、八边形等，也可以为圆形或椭圆形。本发明的其他实施例中，开口110a´的纵截面形状还可以是上宽下窄的球冠，即其纵向截面为U形。
本实施例中，在形成支撑层101之前，在第一电极层103´上还形成刻蚀停止层102，其材质包括但不限于氮化硅（Si3N4）和氮氧化硅（SiON）。刻蚀停止层102与后续形成的支撑层101相比，具有较低的刻蚀速率，可以在后续刻蚀支撑层101形成开口110a´时防止过刻蚀，保护位于其下的第一电极层103´的表面不受到损伤。
接着，刻蚀第一电极层103´和压电层104以在开口110a´内形成第一沟槽120a。如图9所示，第一沟槽120a的侧壁可以是倾斜或者竖直的。本实施例中，第一沟槽120a的侧壁与第二电极105所在平面构成一钝角（第一沟槽120a的纵向截面（沿衬底厚度方向的截面）形状为倒梯形）。第一沟槽120a在压电层104所在平面的投影为一半环形或类似半环形的多边形。在其他实施例中，参考图2C，也可以形成多个不连续的第一沟槽120a，使多个第一沟槽120a在压电层104所在平面的投影为一不连续的半环形。具体地，刻蚀第一沟槽的刻蚀工艺为干法刻蚀工艺，干法刻蚀包括但不限于感应耦合等离子体（ICP）刻蚀、反应离子刻蚀(RIE)、离子束刻蚀、等离子体刻蚀或者激光切割，刻蚀出的第一沟槽120a的侧壁与第二电极105所在平面的夹角α为钝角，优选地，90< α <160。
然后，对第一电极层103´图形化形成第一电极103。具体地，对第一电极层103´表面涂光刻胶形成光刻胶层，通过预设第一电极图案的第一掩膜版对光刻胶层进行光刻形成图案，将图案化后的光刻胶层作为掩膜，然后通过干法刻蚀工艺刻蚀第一电极层103´，刻蚀形成的第一电极103包括第一电极搭接区1031和第一电极谐振区1032，第一电极谐振区1032与有效谐振区001重叠，形成的第一电极搭接区1031连接第一电极谐振区1031和空腔***的支撑层，在本实施例，参考图2C第一电极搭接区1031为桥结构。在其他实施例中，第一电极搭接区1031也可以为连接支撑层101多个边的面状结构或多个桥结构。需要说明的是，对第一电极图形化的实施过程中，可以将第一电极层103´中除第一电极搭接区1031和第一电极谐振区1032以外的区域全部刻蚀掉，也可以只将第一电极103与第一电极层103´中的其他区域进行电隔离，具体可以通过刻蚀第一电极层103´中定义的第一电极103图形的边界（第一沟槽120a定义出的第一电极边界以外区域），并将第一电极层103´贯穿，沿第一电极103图形的边界刻蚀出具有一定线宽的缝隙，最后将第一电极103从第一电极层103´中完全分离出来，第一电极层103´中其他区域仍可保留，实现电分离。
参考图10所示，执行步骤S03，将第一衬底100与支撑层101进行键合，第一衬底100与第一电极103在支撑层101的开口110a´处形成空腔110a。第一衬底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。可以通过热压键合或干膜键合的方式实现第一衬底100与支撑层101的键合。完成键合工艺后，将键合后的上述薄膜体声波谐振器进行翻转以进行后续步骤。
在本发明其他实施例中，第一沟槽120a和空腔110a的形成方法还包括：
提供第一衬底100，在第一衬底100上形成支撑层101，刻蚀支撑层101暴露出部分第一衬底100，进而在支撑层101中形成开口110a´；刻蚀第一电极103和压电层104形成第一沟槽120a；将形成有开口110a´的支撑层101与形成有第一沟槽120a的压电叠层120进行键合以形成空腔110a。
其中，制作第一沟槽120a和具有开口110a´的支撑层101工艺步骤并没有时间先后的限制，本领域技术人员可以根据实际制程条件具体实施。
参考图11所示，执行步骤S04，去除第二衬底200，本实施例中通过腐蚀隔离层的方式剥离第二衬底200。在本发明的其他实施例中可以采用其他方式将第二衬底200去除，例如刻蚀或机械研磨等方式。
参考图12至图13所示，执行步骤S05，刻蚀第二电极层105´和压电层104以形成第二沟槽120b，第一沟槽120a和第二沟槽120b在压电层104所在的平面上的投影围成一个闭合或近似闭合图形。
具体的，刻蚀第二电极105和压电层104以形成第二沟槽120b，如图13所示。第二沟槽120b的侧壁可以是倾斜或者竖直的。本实施例中，第二沟槽120b的侧壁与第一电极层103´所在平面构成一钝角（第二沟槽120b的纵向截面（沿衬底厚度方向的截面）形状为倒梯形）。第二沟槽120b在压电层104所在平面的投影为半环形或类似半环形的多边形。在其他实施例中，参考图2C，也可以形成多个不连续的第二沟槽120a，使多个第二沟槽120a在压电层104所在平面的投影形成不连续的半环形。具体地，刻蚀第二沟槽的刻蚀工艺为干法刻蚀工艺，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，刻蚀出的第二沟槽120a的侧壁与第一电极103所在平面的夹角β为钝角，优选地，90<β<160。
然后，对第二电极层105´图形化形成第二电极105。具体地，对第二电极层105´表面涂光刻胶形成光刻胶层，通过预设第一电极图案的第一掩膜版对光刻胶层进行光刻形成图案，将图案化后的光刻胶层作为掩膜，然后通过干法刻蚀工艺刻蚀第二电极层105´，刻蚀形成的第二电极105包括第二电极搭接区1051和第二电极谐振区1052，第二电极谐振区1052与有效谐振区001重叠，形成的第二电极搭接区1051连接第二电极谐振区1052和空腔***的压电叠层，在本实施例，参考图2A第二电极搭接区1051为桥结构。在其他实施例中，第二电极搭接区1051也可以为一端连接第二电极搭接区1051，另一端连接空腔***压电叠层边缘的面状结构或多个桥结构。其中第二电极搭接区1051与第一电极搭接区1031在空腔上方不重叠，以减少空腔上方非谐振有效区（无效谐振区002）的寄生谐振。需要说明的是，对第二电极图形化的实施过程中，可以将第二电极层105´中除第二电极搭接区1051和第二电极谐振区1052以外的区域全部刻蚀掉，也可以只将第二电极105与第二电极层105´中的其他区域进行电隔离，如通过刻蚀第二电极层105´中定义的第二电极105图形的边界（第二沟槽120b定义出的第二电极边界以外区域），并将第二电极层105´贯穿，沿第二电极103图形的边界刻蚀出具有一定线宽的缝隙，最后将第二电极105从第二电极层105´中完全分离出来，第二电极层105´中其他区域仍可保留，实现电分离。
另外，第一沟槽120a和第二沟槽120b沿图2A中AA´线的截面为梯形或类梯形（即 α、β为钝角），本实施例中，第一沟槽120a和第二沟槽120b在压电层104所在的平面上的投影围成的图形（有效谐振区001）为正好相接的五边形，且多边形不包含任何一对相对平行的直线段。在本发明其他实施例中，第一沟槽120a和第二沟槽120b在压电层104所在的平面上的投影组成的图形也可以是在两处衔接处具有间隙（第一衔接处间隙150a´和第二衔接处间隙150b´）的接近闭合的五边形，如图2B所示。本实施例中，可以在边缘部分105a上形成第二焊盘107b。另外，刻蚀第二电极105和压电层104形成第二沟槽120b的过程中，可以刻蚀部分第二电极105（边缘部分105a）和压电层104暴露第一电极103一侧的边缘部分103a，以便于第一电极103的信号输入/输出，例如可以在边缘部分103a上形成第一焊盘107a。
综上，本发明提供的薄膜体声波谐振器及其制造方法和滤波器、射频通信***。本发明提供的薄膜体声波谐振器在压电叠层中设置第一沟槽和第二沟槽，第一沟槽和第二沟槽在压电层所在的平面上的投影围成薄膜体声波谐振器的有效谐振区，本发明中第一沟槽和第二沟槽有效阻断了横波在无效谐振区的传播，改善了声波损耗，使薄膜体声波谐振器的品质因子得到提高，进而提高器件性能。同时，图形化的第一电极搭接区和第二电极搭接区在空腔上方不重叠，有效避免了压电叠层非有效谐振区的寄生谐振，进一步提高薄膜体声波谐振器的品质因子。
需要说明的是，本说明书中的各个实施例均采用相关的方式描述，各个实施例之间相同相似的部分互相参见即可，每个实施例重点说明的都是与其他实施例的不同之处。尤其，对于结构实施例而言，由于其基本相似于方法实施例，所以描述的比较简单，相关之处参见方法实施例的部分说明即可。
上述描述仅是对本发明较佳实施例的描述，并非对本发明范围的任何限定，本发明领域的普通技术人员根据上述揭示内容做的任何变更、修饰，均属于权利要求书的保护范围。

Claims (19)

  1. 一种薄膜体声波谐振器，其特征在于，包括：
    第一衬底及设置于所述第一衬底上的支撑层，所述支撑层中设置有顶部开口的空腔；
    盖设于空腔上的压电叠层，包括依次设置在所述支撑层上的第一电极、压电层和第二电极，所述压电叠层包括位于所述空腔中央上方的有效谐振区和包围所述效谐振区的无效谐振区；
    至少两个沟槽，分布于所述有效谐振区和无效谐振区的交界处以界定有效谐振区的范围，所述沟槽包括第一沟槽和第二沟槽，所述第二沟槽贯穿所述第二电极和所述压电层，所述第一沟槽贯穿所述第一电极和所述压电层并与所述空腔连通。
  2. 根据权利要求1所述的薄膜体声波谐振器，其特征在于，所述第一沟槽的侧壁与所述第二电极所在平面的夹角为钝角，所述第二沟槽的侧壁与所述第一电极所在平面的夹角为钝角。
  3. 根据权利要求1所述的薄膜体声波谐振器，其特征在于，所述支撑层与第一衬底键合连接。
  4. 根据权利要求3所述的薄膜体声波谐振器，其特征在于，所述键合的方式包括热压键合和干膜键合。
  5. 根据权利要求1所述的薄膜体声波谐振器，其特征在于，所述有效谐振区在所述压电层所在平面的投影为多边形，且所述多边形的任意两边不平行。
  6. 根据权利要求1所述的薄膜体声波谐振器，其特征在于，所述第一电极还包括第一电极搭接区和第一电极谐振区，所述第一电极谐振区与所述有效谐振区重叠，所述第一电极搭接区连接第一电极谐振区和所述支撑层。
  7. 根据权利要求1所述的薄膜体声波谐振器，其特征在于，所述第二电极还包括第二电极搭接区和第二电极谐振区，所述第二电极谐振区与所述有效谐振区重叠，所述第二电极搭接区连接第二电极谐振区和所述空腔***的压电叠层，所述第二电极搭接区与所述第一电极搭接区在所述压电层平面的投影不重叠。
  8. 根据权利要求1所述的薄膜体声波谐振器，其特征在于，所述支撑层的材料包括氧化硅、氮化硅、氮氧化硅、碳氮化硅中的至少一种。
  9. 根据权利要求1所述的薄膜体声波谐振器，其特征在于，所述压电层的材料包括氮化铝、氧化锌、锆钛酸铅、铌酸锂、石英、铌酸钾中的至少一种。
  10. 一种滤波器，其特征在于，包括至少一个如权利要求1至9中任一项所述的薄膜体声波谐振器。
  11. 一种射频通信***，其特征在于，包括至少一个如权利要求10所述的滤波器。
  12. 一种薄膜体声波谐振器的制造方法，其特征在于，包括：提供第二衬底，在所述第二衬底上形成压电叠层，所述压电叠层包括依次形成在所述第二衬底上的第二电极层、压电层及第一电极层；
    在所述第一电极层上形成支撑层，在所述支撑层中形成具有开口的空腔以暴露部分所述第一电极层；
    刻蚀所述第一电极层和所述压电层形成至少一个第一沟槽，所述第一沟槽与所述空腔连通；
    提供第一衬底，将所述第一衬底与所述支撑层键合以封闭所述空腔的开口；
    去除所述第二衬底；
    刻蚀所述第二电极层和所述压电层形成至少一个第二沟槽，所述第一沟槽和所述第二沟槽在所述压电层所在平面上的投影围成有效谐振区。
  13. 如权利要求12所述的薄膜体声波谐振器的制造方法，其特征在于，在所述刻蚀所述第一电极层和所述压电层形成至少一个第一沟槽步骤中，包括：通过第一光罩图形，刻蚀所述第一电极层和所述压电层，形成至少一个所述第一沟槽，所述第一沟槽的侧壁与所述第二电极层所在平面的夹角为钝角。
  14. 如权利要求12所述的薄膜体声波谐振器的制造方法，其特征在于，在所述刻蚀所述第一电极层和所述压电层形成至少一个第一沟槽步骤中，还包括：图形化所述第一电极层形成第一电极，所述第一电极包括第一电极搭接区和第一电极谐振区，所述第一电极谐振区与所述有效谐振区重叠，所述第一电极搭接区连接第一电极谐振区和所述支撑层。
  15. 如权利要求12所述的薄膜体声波谐振器的制造方法，其特征在于，在所述刻蚀所述第二电极层和所述压电层形成至少一个第二沟槽步骤中，包括：通过第二光罩图形，刻蚀所述第二电极层和所述压电层，形成至少一个所述第二沟槽，所述第二沟槽的侧壁与所述第一电极层所在平面的夹角为钝角。
  16. 如权利要求14所述的薄膜体声波谐振器的制造方法，其特征在于，在所述刻蚀所述第二电极层和所述压电层形成至少一个第二沟槽步骤中，还包括：图形化所述第二电极层形成第二电极，所述第二电极包括第二电极搭接区和第二电极谐振区，所述第二电极谐振区与所述有效谐振区重叠，所述第二电极搭接区连接第二电极谐振区和所述空腔***的所述压电叠层，所述第二电极搭接区与所述第一电极搭接区在所述压电层的投影不重叠。
  17. 如权利要求12所述的薄膜体声波谐振器的制造方法，其特征在于，所述谐振有效区的形状为多边形，且所述多边形的任意两边不平行。
  18. 如权利要求12所述的薄膜体声波谐振器的制造方法，其特征在于，在取出所述第二衬底步骤中，包括：通过机械研磨、刻蚀或腐蚀方式去除所述第二衬底。
  19. 如权利要求12所述的薄膜体声波谐振器的制造方法，其特征在于，在所述将所述第一衬底与所述支撑层键合以封闭所述空腔的开口步骤中，包括：通过热压键合工艺或干膜键合工艺将所述第一衬底与所述支撑层键合在一起。
PCT/CN2020/099647 2019-07-19 2020-07-01 薄膜体声波谐振器及其制造方法和滤波器、射频通信*** WO2021012917A1 (zh)

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