WO2020098480A1 - 体声波谐振器、滤波器和电子设备 - Google Patents

体声波谐振器、滤波器和电子设备 Download PDF

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Publication number
WO2020098480A1
WO2020098480A1 PCT/CN2019/113999 CN2019113999W WO2020098480A1 WO 2020098480 A1 WO2020098480 A1 WO 2020098480A1 CN 2019113999 W CN2019113999 W CN 2019113999W WO 2020098480 A1 WO2020098480 A1 WO 2020098480A1
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resonator according
resonator
top electrode
piezoelectric layer
fracture
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PCT/CN2019/113999
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English (en)
French (fr)
Inventor
张孟伦
庞慰
刘伯华
杨清瑞
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天津大学
诺思(天津)微系统有限责任公司
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Publication of WO2020098480A1 publication Critical patent/WO2020098480A1/zh

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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
    • H03H9/02039—Characteristics of piezoelectric layers, e.g. cutting angles consisting of a material from the crystal group 32, e.g. langasite, langatate, langanite
    • 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
    • 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
    • H03H9/02244—Details of microelectro-mechanical resonators

Definitions

  • Embodiments of the present invention relate to the field of semiconductors, and in particular, to a bulk acoustic wave resonator and a method of manufacturing the same, a filter having the resonator, and an electronic device having the filter.
  • multi-passband transceivers that can process large amounts of data simultaneously.
  • multi-passband transceivers have been widely used in positioning systems and multi-standard systems. These systems need to process signals in different frequency bands simultaneously to improve the overall performance of the system.
  • the number of frequency bands in a single chip continues to increase, consumers' demand for miniaturized and multi-functional portable devices is increasing. Miniaturization has become the development trend of chips, which puts forward a higher filter size Requirements.
  • a film bulk acoustic resonator (Film Bulk Acoustic Resonator, FBAR for short) has been used to replace the traditional waveguide technology to implement a multi-band filter.
  • FBAR mainly uses the piezoelectric effect and inverse piezoelectric effect of piezoelectric materials to generate bulk acoustic waves, thereby forming resonance in the device, because FBAR has high quality factor, large power capacity, high frequency (up to 2-10GHz or even higher) and A series of inherent advantages, such as good compatibility with standard integrated circuits (ICs), can be widely used in higher frequency RF application systems.
  • ICs integrated circuits
  • the main body of the FBAR structure is a "sandwich" structure composed of electrodes-piezoelectric films-electrodes, that is, a layer of piezoelectric material is sandwiched between two metal electrode layers.
  • FBAR uses the inverse piezoelectric effect to convert the input electrical signal into mechanical resonance, and then uses the piezoelectric effect to convert the mechanical resonance into electrical signal output.
  • FBAR mainly uses the longitudinal piezoelectric coefficient (d33) of the piezoelectric film to generate the piezoelectric effect, so its main working mode is the longitudinal extension mode (Thickness Extensional Mode, TE mode for short) in the thickness direction.
  • the electromechanical coupling coefficient Kt 2 value is an important parameter of the resonator. This parameter represents the ability of the resonator to convert mechanical energy and electrical energy. In the case where the other performance indexes of the resonator are the same, the larger the Kt 2 value, the better the performance of the resonator.
  • the thin film bulk acoustic resonator only excites the thickness direction (TE) mode, but in addition to the desired TE mode, it will also produce a lateral parasitic mode, such as the Rayleigh-Ram mode is perpendicular to the direction of the TE mode Mechanical wave.
  • TE thickness direction
  • lateral parasitic mode such as the Rayleigh-Ram mode is perpendicular to the direction of the TE mode Mechanical wave.
  • the acoustic wave at the edge can be reflected back into the resonator, and at the same time part of the energy will be converted into a mode of vertical vibration , So that the Q value of the resonator can be improved.
  • the existence of the broken structure will cause the resonator to increase the Q value and bring about a drop in the resonator electromechanical coupling coefficient, that is, Kt 2 .
  • Kt 2 the resonator electromechanical coupling coefficient
  • the present invention proposes a scheme for doping rare earth elements in the piezoelectric layer material.
  • a bulk acoustic wave resonator including: a substrate; an acoustic mirror; a bottom electrode disposed above the substrate; a top electrode opposing the bottom electrode, the top electrode having The main body part and the connection part connected to the main body part; the piezoelectric layer provided above the bottom electrode and between the bottom electrode and the top electrode, the piezoelectric layer doped with rare earth elements; and the passivation layer provided on the top electrode
  • the area where the acoustic mirror, bottom electrode, piezoelectric layer, and top electrode overlap in the thickness direction of the substrate is the effective area of the resonator, the passivation layer is adjacent to the boundary of the effective area, above the connection portion At least one first breaking structure is provided.
  • the piezoelectric layer material is doped with rare earth elements, due to the relatively large atomic radius of the rare earth element, the stress in the piezoelectric material changes, which in turn causes the electric dipole in the piezoelectric material to change.
  • an electric field is applied to the piezoelectric material, a larger mechanical response will be generated in the piezoelectric material, so that the resonator can obtain a higher electromechanical coupling coefficient (Kt 2 ).
  • the connecting portion has an inclined surface, and the first breaking structure is provided at the inclined surface.
  • the connection portion forms a bridge structure, and an air gap is formed between the bridge structure and the piezoelectric layer, and the inclined surface includes a first inclined surface adjacent to the boundary of the bridge structure and a top electrode lead The second inclined surface, the first breaking structure is provided at the first inclined surface.
  • the passivation layer further includes at least one second fracture structure provided at the second inclined surface.
  • connection portion is a horizontal connection portion.
  • the top electrode is further provided with a bridge wing structure on a side opposite to the connection portion, the bridge wing structure has a bridge wing slope, and an air gap is formed between the bridge wing structure and the piezoelectric layer.
  • the passivation layer further includes at least one third fracture structure disposed above the slope of the bridge wing.
  • the depth of the broken structure is smaller than the thickness of the passivation layer. Further, the depth of the broken structure is 5% -30% of the thickness of the passivation layer. Optionally, the range of the depth of the fracture structure is
  • the depth of at least part of the fracture structure is equal to the thickness of the passivation layer.
  • the value range of the thickness of the passivation layer is
  • At least one fourth fracture structure is provided in the piezoelectric layer below the top electrode or laterally outside of the top electrode, adjacent to the boundary of the effective region.
  • the width of the fourth fracture structure is 1-10% of the lateral width of the effective area.
  • the depth of the fourth fracture structure is 1-15% of the thickness of the piezoelectric layer.
  • the value range of the depth of the fourth fracture structure is
  • the width of the broken structure ranges from 0.1 to 10 ⁇ m.
  • the cross-sectional shape of the broken structure is one of an arc shape, an inclined shape, a stepped shape, and a fan shape.
  • doped rare earth elements include lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), Gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), and yttrium (Y) and scandium (Sc) One or any number of elements.
  • the doped rare earth element includes scandium (Sc).
  • the piezoelectric layer material is aluminum nitride (ALN), which is doped to form an Al 1-a X a N or Al 1-ab X a Y b N structure, where X and Y represent In any two of the above rare earth elements, a and b represent the content of doping elements X and Y, respectively.
  • ABN aluminum nitride
  • the atomic fraction of the doping element X or Y may be 0.5% -30%.
  • Embodiments of the present invention also relate to a filter, including the bulk acoustic wave resonator described above.
  • Embodiments of the present invention also relate to an electronic device, including the aforementioned filter.
  • 1A and 1B are respectively a schematic plan view and a cross-sectional view taken along the direction of 1B-1B of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention
  • 2A and 2B are respectively a schematic plan view and a cross-sectional view in the direction of 1B-1B of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention
  • 3A and 3B are respectively a schematic plan view and a cross-sectional view taken along the direction of 1B-1B of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention
  • 4A and 4B are respectively a schematic plan view and a cross-sectional view in the direction of 1B-1B of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention
  • 5A and 5B are respectively a schematic plan view and a cross-sectional view in the direction of 1B-1B of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention
  • 6A and 6B are respectively a schematic plan view and a cross-sectional view taken along the direction of 1B-1B of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention
  • FIG. 7 is a schematic cross-sectional view of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention.
  • FIG. 8 is a schematic cross-sectional view of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention.
  • the present invention forms a broken structure at the edge of the effective area of the resonator. Since the acoustic impedance of the broken structure does not match the acoustic impedance of the effective area of the resonator, the sound wave is reflected back into the resonator at the edge, effectively preventing the energy in the resonator Give way.
  • FIGS. 1-8 a bulk acoustic wave resonator according to an embodiment of the present invention will be described with reference to FIGS. 1-8.
  • FIG. 1A is a top view of a thin film bulk acoustic resonator according to an exemplary embodiment of the present invention.
  • the FBAR includes a bottom electrode 105, a piezoelectric layer 107, a top electrode 109, a passivation layer 111, and a passivation layer 113 located above the step where the top electrode 109 and its electrode are connected.
  • the piezoelectric layer material is doped with rare earth elements.
  • a typical piezoelectric material is aluminum nitride (AlN), which has a wurtzite structure, that is, a hexagonal crystal system, and the polarization axis direction is (0001).
  • Doped rare earth elements include: lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb ), Dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), and one or more of yttrium (Y) and scandium (Sc) .
  • the doped rare earth element includes scandium (Sc).
  • the doping method can be one or any two rare earth elements X and / or Y to replace Al atoms in the AlN crystal structure to form Al 1-a X a N or Al 1-ab X a Y b N structure, where X and Y represent any two of the above rare earth elements, and a and b represent the content of doped atoms X and Y.
  • the atomic fraction of the rare earth element X or Y may be 0.5% -30%, and the content of the doped rare earth elements X and Y may be the same or different.
  • FIG. 1B is a cross-sectional view taken along line 1B-1B in FIG. 1A.
  • the resonator includes a substrate 101 in order in the thickness direction; an acoustic mirror 103, which is located on the upper surface of the substrate or embedded inside the substrate.
  • the acoustic mirror is a cavity embedded in the substrate Structure, but any other acoustic mirror structure such as a Bragg reflector is also suitable; bottom electrode 105; piezoelectric layer 107, piezoelectric layer doped with any two rare earth elements; top electrode 109; passivation layer 111.
  • the passivation layer can protect the electrode, prevent the material from adsorbing on the resonator surface, eliminate or reduce the oxidation and corrosion of the device due to the influence of the surrounding air or humid environment, thereby causing the resonator frequency to shift;
  • the passivation layer can also be processed to fine-tune the frequency of the resonator; and the presence of the passivation layer can reduce the requirements for the hermetic packaging of the resonator and reduce the cost of device fabrication.
  • the passivation layer above the step where the top electrode and its electrode are connected has a fracture structure 113, and the fracture mode is only partial (that is, it is not completely disconnected).
  • the cross-sectional shape of the broken structure 113 can also be other shapes such as the inclined shape in FIG. 1D, the stepped shape in FIG. 1E, and the fan shape in FIG. 1F.
  • the broken structure has a fixed width w and depth h.
  • the depth of the fracture structure is less than the thickness of the passivation layer, for example, 5% -30% of the thickness of the passivation layer, and its typical w range is 0.1-10 ⁇ m, and the depth of h is
  • the fracture structure can be obtained by wet etching or dry etching and other similar processes.
  • the width and depth of the fracture structure can be controlled by controlling the time of wet etching and the ratio of the chemical solution, or by controlling the dry etching. Time, power, and the flow and ratio of etching gas control the width and depth of the fracture structure.
  • the area where the acoustic mirror 103, the bottom electrode 105, the piezoelectric layer 107, and the top electrode 109 overlap in the thickness direction is the effective area of the resonator, has a first acoustic impedance, and has a second acoustic impedance in the fracture structure 113 of the passivation layer 111 . Because the second acoustic impedance in the fracture structure 113 of the passivation layer 111 does not match the first acoustic impedance, and because the fracture structure has a certain depth, the acoustic wave will form a local oscillation at the fracture structure.
  • FIGS. 2A and 2B are respectively a schematic plan view and a cross-sectional view taken along the direction of 1B-1B of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention.
  • FIGS. 2A and 2B are respectively a schematic plan view and a cross-sectional view taken along the direction of 1B-1B of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention.
  • the FBAR includes a bottom electrode 205, a piezoelectric layer 207, a top electrode 209, a passivation layer 211, and a passivation layer 213 located above the step where the top electrode and its electrode are connected.
  • the structure of the piezoelectric resonator shown in FIG. 2B is similar to the structure of the embodiment shown in FIG. 1B, and they are all cross-sectional views taken along the top views 1B-1B.
  • the difference lies in the fracture structure 213 of the passivation layer above the step where the top electrode and its electrode are connected.
  • the cross-sectional shape of the fracture structure 213 may be an arc shape in FIG. 1C, or an inclined shape in FIG. 1D, a step shape in FIG. 1E, and a fan shape in FIG. 1F.
  • the top electrode to the bottom is deeper.
  • the depth of the fracture structure 213 is the same as the thickness of the passivation layer, the typical w range is 0.1-10 ⁇ m, and the depth h is
  • the degree of mismatch between the second acoustic impedance and the first acoustic impedance of the fracture structure in the passivation layer can be further increased, so that the discontinuity of sound wave transmission at the boundary is enhanced, so at the boundary of the effective area
  • the existence of the broken structure will raise the Q value of the resonator, and will bring about the problem of Kt 2 decline.
  • the piezoelectric layer material is doped with rare earth elements to increase its Kt 2 to compensate The shortcomings of the broken structure.
  • 3A and 3B are respectively a schematic plan view and a cross-sectional view taken along the direction of 1B-1B of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention.
  • FIGS. 3A and 3B are respectively a schematic plan view and a cross-sectional view taken along the direction of 1B-1B of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention.
  • the FBAR includes a bottom electrode 305, a piezoelectric layer 307, a top electrode 309, a passivation layer 311, and a passivation layer 313 and 315 in the passivation layer above the step where the top electrode and its electrode are connected.
  • the structure of the piezoelectric resonator shown in FIG. 3B is similar to the structure of the embodiment shown in FIG. 1B, and they are all cross-sectional views taken along the top views 1B-1B.
  • the difference lies in the fracture structure of the passivation layer above the step where the top electrode and its electrode are connected.
  • the fractured part contains 313 and 315.
  • the fracture structure can have a circular arc shape as shown in FIG. 1C or as shown in FIG. 1D
  • the inclined shape in Fig. 1E, the stepped shape in Fig. 1E, and the fan shape in Fig. 1F, etc., the fracture mode is multiple locations including but not limited to two, and the fracture depth is shallow.
  • the broken portion has two fixed widths w1 and w2 and two broken depths h1 and h2.
  • the depth of the fracture structure is less than the thickness of the passivation layer, for example, 5% -30% of the thickness of the passivation layer, and its typical w1 and w2 ranges from 0.1-10 ⁇ m, h1 and h2 depths.
  • the existence of the broken structure will raise the Q value of the resonator, and will bring about the problem of Kt 2 decline.
  • the piezoelectric layer material is doped with rare earth elements to increase its Kt 2 to compensate The shortcomings of the broken structure.
  • the doped rare earth element may be one kind, or two or more kinds.
  • the present invention proposes a bulk acoustic wave resonator including: a substrate; an acoustic mirror; a bottom electrode provided above the substrate; a top electrode opposed to the bottom electrode, the top electrode having a body portion and a body Connection part; piezoelectric layer, which is arranged above the bottom electrode and between the bottom electrode and the top electrode, the piezoelectric layer is doped with rare earth elements; and a passivation layer, which is arranged above the top electrode, where: acoustic mirror, The area where the bottom electrode, the piezoelectric layer, and the top electrode overlap in the thickness direction of the substrate is an effective area of the resonator, the passivation layer is adjacent to the boundary of the effective area, and at least one first break is provided above the connection portion structure.
  • connection portion may be the connection between the top electrode and its electrode lead, which is embodied as an inclined surface.
  • the breaking structure is provided at the inclined surface.
  • connection part not only includes the broken structure only provided directly above the connection part (in the lateral direction, between two vertical boundaries of the connection part), but also Including the case where the broken structure is provided diagonally above the connecting portion.
  • the rupture structure is provided at the inclined surface, including not only the case where it is provided within the range of the inclined surface, but also the case where it is provided near the inclined surface.
  • connection portion may be a horizontal connection portion.
  • the fracture structure may be provided at other locations besides the connection portion.
  • the electrode composition material may be gold (Au), tungsten (W), molybdenum (Mo), platinum (Pt), ruthenium (Ru), iridium (Ir), titanium tungsten (TiW), aluminum (Al) , Titanium (Ti) and similar metals.
  • the piezoelectric layer material may be 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 materials.
  • the passivation layer material may be aluminum nitride (AlN), silicon carbide (SiC), aluminum oxide (Al 2 O 3 ), silicon oxide (SiO 2 ), silicon nitride (Si 3 N 4 ) or Their combination and other materials.
  • the resonator includes a substrate 701 in order in the thickness direction; an acoustic mirror 703, which is located on the upper surface of the substrate or embedded inside the substrate.
  • the resonator includes a substrate 701 in order in the thickness direction; an acoustic mirror 703, which is located on the upper surface of the substrate or embedded inside the substrate.
  • the acoustic mirror is a cavity embedded in the substrate Structure, but any other acoustic mirror structure such as a Bragg reflector is also suitable; bottom electrode 705; piezoelectric layer 707, which is doped with rare earth elements; top electrode 709, which consists of two parts, the body part and the connection part, The connection part is a bridge wing structure, and there is an air gap between the connection part of the top electrode and the piezoelectric layer; the passivation layer 711, the fracture structures 715 and 713 included at the step, the cross-sectional shape of the fracture structure can be as shown in FIG. 1C
  • the arc shape can also be other shapes such as the inclined shape in FIG. 1D, the stepped shape in FIG. 1E, and the fan shape in FIG.
  • the fracture mode is partial fracture, and has a fixed width w1, w2 and fracture depth h1, h2.
  • the depth of the fracture structure is less than the thickness of the passivation layer, for example, 5% -30% of the thickness of the passivation layer, and its typical w1 and w2 ranges from 0.1-10 ⁇ m, h1 and h2 depths
  • the acoustic impedance does not match the acoustic impedance in the effective area of the resonator, which will cause the sound wave to be transmitted discontinuously at the boundary, so at the boundary of the effective area Part of the acoustic energy will be coupled and reflected into the effective excitation area, and converted into a piston acoustic wave mode perpendicular to the surface of the piezoelectric layer, so that the Q value of the resonator is improved.
  • the existence of the bridge wing structure and the broken structure will raise the Q value of the resonator, and will bring about the problem of Kt 2 decline.
  • the piezoelectric layer material is doped with rare earth elements to increase its Kt 2.
  • the resonator includes a substrate 801 in order in the thickness direction; an acoustic mirror 803, which is located on the upper surface of the substrate or embedded inside the substrate.
  • the resonator includes a substrate 801 in order in the thickness direction; an acoustic mirror 803, which is located on the upper surface of the substrate or embedded inside the substrate.
  • the acoustic mirror is a cavity embedded in the substrate Structure, but any other acoustic mirror structure such as a Bragg reflector is also suitable; bottom electrode 805; piezoelectric layer 807, piezoelectric layer doped with rare earth elements; top electrode 809, including the main body portion and the connection portion, wherein the connection portion For the bridge structure, there is an air gap between the connection part of the top electrode and the piezoelectric layer; the passivation layer 811 contains the broken structures 815 and 813 at the step.
  • connection portion forms a bridge structure, and an air gap is formed between the bridge structure and the piezoelectric layer, and the inclined surface includes the first portion of the bridge structure adjacent to the boundary
  • the inclined surface and the second inclined surface adjacent to the top electrode lead are provided with a broken structure at the first inclined surface, and optionally, the broken structure is also provided at the second inclined surface.
  • the cross-sectional shape of the fracture structure may be an arc shape in FIG. 1C, or an inclined shape in FIG. 1D, a stepped shape in FIG. 1E, and a fan shape in FIG. 1F.
  • the fracture mode is partial fracture, and Has a fixed width w1, w2 and fracture depth h1, h2.
  • the depth of the fracture structure is less than the thickness of the passivation layer, for example, 5% -30% of the thickness of the passivation layer, and its typical w1 and w2 ranges from 0.1-10 ⁇ m, h1 and h2 depths
  • the acoustic impedance does not match the acoustic impedance in the effective area of the resonator, which makes the transmission of sound waves discontinuous at the boundary of the effective area, so it is effective
  • part of the acoustic energy will be coupled and reflected into the effective excitation region, and converted into a piston acoustic wave mode perpendicular to the surface of the piezoelectric layer, so that the Q value of the resonator is improved.
  • the existence of the bridge structure and the broken structure will raise the Q value of the resonator, and will bring about the problem of Kt 2 decline.
  • the piezoelectric layer material is doped with rare earth elements to increase its Kt 2.
  • 4A and 4B are respectively a schematic plan view and a cross-sectional view taken along the direction of 1B-1B of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention.
  • the FBAR includes a bottom electrode 405, a piezoelectric layer 407, a top electrode 409, a passivation layer 411, a fracture structure 413 inside the top electrode between the top electrode and the piezoelectric layer, and the top electrode and its electrode
  • the passivation layer above the step at the junction has a fracture structure 415.
  • the resonator includes a substrate 401 in order in the thickness direction; an acoustic mirror 403, which is located on the upper surface of the substrate or embedded inside the substrate.
  • the acoustic mirror is a cavity embedded in the substrate Structure, but any other acoustic mirror structure such as a Bragg reflector is also suitable; bottom electrode 407; piezoelectric layer 407, piezoelectric layer doped with rare earth elements; top electrode 409; passivation layer 411; and the top electrode and The fracture structure 413 located inside the top electrode between the piezoelectric layers and the fracture structure 415 located in the passivation layer above the step (corresponding to the connection) between the top electrode and its electrode connection.
  • the cross-sectional shapes of the fracture structures 413 and 415 may be the arc shape in FIG. 1C, or the inclined shape in FIG. 1D, the step shape in FIG. 1E, and the fan shape in FIG. 1F, etc., with a fixed width w1 , W2 and fracture depth h1, h2.
  • the fracture structure can be obtained by wet etching or dry etching and other similar processes.
  • the width and depth of the fracture structure can be controlled by controlling the time of wet etching and the ratio of the chemical solution, or by controlling the dry etching. Time, power, and the flow and ratio of etching gas control the width and depth of the fracture structure.
  • the area where the acoustic mirror, the bottom electrode, the piezoelectric layer, and the top electrode overlap in the thickness direction is the effective area of the resonator, and has the first acoustic impedance in the fracture structure 415 of the passivation layer It has a second acoustic impedance and a third acoustic impedance in the fracture structure 413 in the piezoelectric layer.
  • the transmission of sound waves at the boundary is discontinuous, so the boundary At this point, part of the acoustic energy will be coupled and reflected into the effective excitation area, and converted into a piston acoustic wave mode perpendicular to the surface of the piezoelectric layer, so that the Q value of the resonator is improved.
  • the depth of the fractured structure is shallow, it will not damage the piezoelectric layer, which will not affect the main mode of the resonator, and can effectively improve the mechanical strength of the resonator and increase the Q value of the resonator.
  • the existence of the broken structure will raise the Q value of the resonator, and will bring about the problem of Kt 2 decline.
  • the piezoelectric layer material is doped with rare earth elements to increase its Kt 2 to compensate The shortcomings of the broken structure.
  • 5A and 5B are respectively a schematic plan view and a cross-sectional view taken along the direction of 1B-1B of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention.
  • the FBAR includes a bottom electrode 505, a piezoelectric layer 507, a top electrode 509, a passivation layer 511, and a fracture structure 513 located outside the top electrode between the top electrode and the piezoelectric layer and located on the top electrode and its electrode
  • the passivation layer above the step at the junction has a fracture structure 515.
  • the structure of the piezoelectric resonator shown in FIG. 5B is similar to the structure of the embodiment shown in FIG. 4B. They are all cross-sectional views taken along the top views 1B-1B. The difference is that: in FIG. 4B, the fracture structure is in Below the top electrode is either covered by the top electrode, or laterally inside the boundary of the effective area, and in FIG. 5B, the fracture structure between the piezoelectric layer and the top electrode is located outside the top electrode, or is in the effective area The lateral outside of the border.
  • the cross-sectional shapes of the fracture structures 513 and 515 may be the arc shape in FIG. 1C, or may be the inclined shape in FIG. 1D, the step shape in FIG. 1E, and the fan shape in FIG.
  • the mechanical strength of the resonator is stronger, and because the depth of the fractured structure is shallow, it will not damage the piezoelectric layer, which will not affect the main resonator ⁇ ⁇ Mode.
  • the second acoustic impedance of the fracture structure 515 of the passivation layer and the third acoustic impedance of the fracture structure 513 in the piezoelectric layer do not match the first acoustic impedance of the effective area of the resonator, which makes the transmission of sound waves discontinuous at the boundary, Therefore, at the boundary of the effective area, part of the acoustic energy is coupled and reflected into the effective excitation area, and is converted into a piston acoustic wave mode perpendicular to the surface of the piezoelectric layer, so that the Q value of the resonator is improved.
  • the existence of the fracture structure will raise the Q value of the resonator, and will bring about the problem of Kt 2 decline.
  • 6A and 6B are respectively a schematic plan view and a cross-sectional view in the direction of 1B-1B of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention.
  • the FBAR includes a bottom electrode 605, a piezoelectric layer 607, a top electrode 609, a passivation layer 611, and fracture structures 615 and 617 having multiple fracture positions inside the top electrode between the top electrode and the piezoelectric layer , Its fracture mode is multiple locations including but not limited to two, and its fracture depth is shallow.
  • the structure of the piezoelectric resonator shown in FIG. 6B is similar to the structure of the embodiment shown in FIG. 4B, and they are all cross-sectional views taken along the top views 1B-1B, except for:
  • the fracture structure between the top electrode and the piezoelectric layer is located inside the top electrode (covered by the top electrode) and the fracture structure includes two parts, namely 615 and 617, and its fracture mode is multiple locations including but not limited to two locations.
  • the fracture structure between the top electrode and the piezoelectric layer has a shallow fracture depth.
  • the cross-sectional shapes of the broken structures 613, 615, and 617 may be the arc shape in FIG. 1C, the inclined shape in FIG. 1D, the step shape in FIG. 1E, and the fan shape in FIG. Other shapes.
  • the fracture structure has fixed widths w1, w2, w3 and fracture depths h1, h2, h3.
  • the width of the fracture structure w2 and w3 is proportional to the lateral width of the effective area of the resonator
  • the range is between 1% and 10%, and the ratio between the depth of the fracture structure and the thickness of the piezoelectric layer is between 1% and 15%.
  • the range of w1, w2, and w3 is 0.1-10 ⁇ m, h1 h2 and h3 depth about.
  • the mechanical strength of the resonator is strong, and at the same time, because the depth of the fracture structure is shallow, it will not damage the piezoelectric layer, which will not affect the resonance The main mode of the device.
  • the mismatch between the acoustic impedance in the fracture structure and the acoustic impedance in the effective area of the resonator is further increased, so that the discontinuity of the sound wave transmission at the boundary will be further enhanced, so At the boundary of the effective area, more acoustic energy will be coupled and reflected into the effective excitation area, and converted into a piston acoustic wave mode perpendicular to the surface of the piezoelectric layer, thereby further increasing the Q value of the resonator.
  • the existence of the broken structure will raise the Q value of the resonator, and will bring about the problem of Kt 2 decline.
  • the piezoelectric layer material is doped with rare earth elements to increase its Kt 2 to compensate The shortcomings of the broken structure.
  • the mentioned numerical range may also be the median or other values between the end point values, which are all within the protection scope of the present invention.
  • Embodiments of the present invention also relate to a filter, including the bulk acoustic wave resonator described above.
  • Embodiments of the present invention also relate to an electronic device, including the aforementioned filter.
  • the electronic devices here include but are not limited to intermediate products such as radio frequency front-ends, filter amplification modules, and terminal products such as mobile phones, WIFI, and drones.
  • the electrode composition material may be gold (Au), tungsten (W), molybdenum (Mo), platinum (Pt), ruthenium (Ru), iridium (Ir), titanium tungsten (TiW), aluminum (Al) , Titanium (Ti) and other similar metals.
  • the passivation layer material may be aluminum nitride (AlN), silicon carbide (SiC), aluminum oxide (Al2O3), silicon oxide (SiO2), silicon nitride (Si3N4), or a combination thereof.

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Abstract

一种体声波谐振器、具有该谐振器的滤波器以及具有该滤波器的电子设备，该谐振器包括：基底；声学镜；底电极，设置在基底上方；顶电极，与底电极对置，顶电极具有主体部以及与主体部连接的连接部；压电层，设置在底电极上方以及底电极与顶电极之间，压电层内掺杂有稀土元素；和钝化层，设置在顶电极上方，其中：声学镜、底电极、压电层、顶电极在基底的厚度方向重叠的区域为谐振器的有效区域，钝化层邻近有效区域的边界、在连接部上方设置有至少一个第一断裂结构，压电层内掺杂有稀土元素。

Description

体声波谐振器、滤波器和电子设备 技术领域
本发明的实施例涉及半导体领域，尤其涉及一种体声波谐振器及其制造方法，一种具有该谐振器的滤波器，以及一种具有该滤波器的电子设备。
背景技术
随着无线通信技术的快速发展，人们对于能同步处理大量数据的多通带收发器的需求与日俱增。近年来，多通带收发器已被广泛地应用在定位系统和多标准的系统中，这些系统需要同时处理不同频段的信号以提高系统的整体性能。虽然单个芯片中频率带的个数不断增加，但消费者对小型化、多功能的便携式设备的需求越来越高，小型化成为芯片的发展趋势，这就对滤波器的尺寸提出了更高的要求。
为此，现有技术中已经采用薄膜体声波谐振器(Film Bulk Acoustic Resonator，简称FBAR)取代传统的波导技术实现多频带滤波器。
FBAR主要利用压电材料的压电效应与逆压电效应产生体声波，从而在器件内形成谐振，因为FBAR具有品质因数高、功率容量大、频率高(可达2-10GHz甚至更高)以及与标准集成电路(IC)的兼容性好等一系列的固有优势，可广泛应用于频率较高的射频应用系统中。
FBAR的结构主体为由电极-压电薄膜-电极组成的“三明治”结构，即两层金属电极层之间夹一层压电材料。通过在两电极间输入正弦信号，FBAR利用逆压电效应将输入电信号转换为机械谐振，并且再利用压电效应将机械谐振转换为电信号输出。FBAR主要利用压电薄膜的纵向压电系数(d33)产生压电效应，所以其主要工作模式为厚度方向上的纵波模式(Thickness Extensional Mode，简称TE模式)。机电耦合系数Kt 2值是谐振器的一项重要参数，这项参数代表了谐振器转换机械能和电能的能力。在谐振器其它性能指标一样的情况下，Kt 2值越大则谐振器的性能越好。
理想地，薄膜体声波谐振器仅激发厚度方向(TE)模，但是除了期望的TE模式之外，还会产生横向的寄生模式，如瑞利-拉姆模是与TE模的方向相垂直的机械波。这些横向模式的波会在谐振器的边界处损失掉，从而使得谐振器所需的纵模的能量损 失，最终导致谐振器Q值下降。通过在谐振器钝化层的台阶处或在压电层与顶电极的边缘处形成断裂结构，可以将边缘处的声波反射回谐振器内，同时一部份能量会转化成垂直方向振动的模式，使得谐振器的Q值得以提升。
但是断裂结构的存在，会使得谐振器在Q值提升的同时会带来谐振器机电耦合系数即Kt 2的下降。例如，当断裂结构的深度增加时，由于断裂结构中反射回谐振器中的横向模式波能量增加，从而导致谐振器中垂直模式的声波能量相对减小，使得谐振器的机电耦合系数下降。
发明内容
为缓解或解决FBAR中设置断裂结构时导致谐振器机电耦合系数即Kt 2的下降的问题，本发明提出对压电层材料进行稀土元素的掺杂的方案。
根据本发明的实施例的一个方面，提出了一种体声波谐振器，包括：基底；声学镜；底电极，设置在基底上方；顶电极，与所述底电极对置，所述顶电极具有主体部以及与主体部连接的连接部；压电层，设置在底电极上方以及底电极与顶电极之间，所述压电层内掺杂有稀土元素；和钝化层，设置在顶电极上方，其中：声学镜、底电极、压电层、顶电极在基底的厚度方向重叠的区域为谐振器的有效区域，所述钝化层邻近所述有效区域的边界、在所述连接部上方设置有至少一个第一断裂结构。
当对压电层材料进行稀土元素的掺杂时，由于稀土元素的原子半径比较大，从而引起压电材料中的应力发生变化，进而导致压电材料中的电偶极子发生改变，此时对压电材料施加一电场时，压电材料中就会产生更大的机械响应，从而可以使得谐振器获得更高的机电耦合系数(Kt 2)。
可选的，所述连接部具有倾斜面，所述第一断裂结构设置在所述倾斜面处。进一步的，所述连接部形成桥部结构，桥部结构与压电层之间形成空气隙，所述倾斜面包括所述桥部结构的邻近所述边界的第一倾斜面以及邻近顶电极引线的第二倾斜面，所述第一断裂结构设置在所述第一倾斜面处。进一步的，所述钝化层还包括设置在所述第二倾斜面处的至少一个第二断裂结构。
可选的，所述连接部为水平的连接部。
可选的，所述顶电极在与所述连接部相对的一侧还设置有桥翼结构，所述桥翼结构具有桥翼斜面，所述桥翼结构与压电层之间形成空气隙。进一步的，所述钝化层还包括设置在所述桥翼斜面上方的至少一个第三断裂结构。
上述谐振器中，可选的，所述断裂结构的深度小于所述钝化层的厚度。进一步的，所述断裂结构的深度为所述钝化层的厚度的5％-30％。可选的，所述断裂结构的深度的取值范围为
Figure PCTCN2019113999-appb-000001
上述谐振器中，可选的，至少部分所述断裂结构的深度等于所述钝化层的厚度。可选的，所述钝化层的厚度的取值范围为
Figure PCTCN2019113999-appb-000002
上述谐振器中，可选的，在所述顶电极的下方或者在所述顶电极的横向外侧，邻近所述有效区域的边界在所述压电层中设置有至少一个第四断裂结构。进一步的，所述第四断裂结构的宽度为所述有效区域的横向宽度的1-10％。进一步的，所述第四断裂结构的深度为所述压电层的厚度的1-15％。可选的，所述第四断裂结构的深度的取值范围为
Figure PCTCN2019113999-appb-000003
上述谐振器中，可选的，所述断裂结构的宽度的取值范围为0.1-10μm。
上述谐振器中，可选的，所述断裂结构的截面形状为圆弧状、倾斜状、阶梯状、扇形状中的一种。
上述谐振器中，可选的，掺杂的稀土元素包括镧(La)、铈(Ce)、镨(Pr)、钕(Nd)、钷(Pm)、钐(Sm)、铕(Eu)、钆(Gd)、铽(Tb)、镝(Dy)、钬(Ho)、铒(Er)、铥(Tm)、镱(Yb)、镥(Lu)，以及钇(Y)和钪(Sc)中的一种或者任意多种元素。在可选的实施例中，掺杂的稀土元素包括钪(Sc)。在可选的实施例中，所述压电层材料为氮化铝(ALN)，掺杂后形成Al 1-aX aN或Al 1-a-bX aY bN结构，其中X、Y代表上述稀土元素中的任意两种元素，a、b分别代表掺杂元素X、Y的含量。可选的，掺杂元素X或Y的原子分数可为0.5％-30％。
本发明的实施例还涉及一种滤波器，包括上述的体声波谐振器。
本发明的实施例还涉及一种电子设备，包括上述的滤波器。
附图说明
以下描述与附图可以更好地帮助理解本发明所公布的各种实施例中的这些和其他特点、优点，图中相同的附图标记始终表示相同的部件，其中：
图1A和图1B分别为根据本发明的一个示例性实施例的体声波谐振器示意性俯视图和1B-1B向的截面图；
图1C、图1D、图1E、图1F作为本发明的示例性实施例，分别示意性示出了断 裂结构的截面形状；
图2A和图2B分别为根据本发明的一个示例性实施例的体声波谐振器示意性俯视图和1B-1B向的截面图；
图3A和图3B分别为根据本发明的一个示例性实施例的体声波谐振器示意性俯视图和1B-1B向的截面图；
图4A和图4B分别为根据本发明的一个示例性实施例的体声波谐振器示意性俯视图和1B-1B向的截面图；
图5A和图5B分别为根据本发明的一个示例性实施例的体声波谐振器示意性俯视图和1B-1B向的截面图；
图6A和图6B分别为根据本发明的一个示例性实施例的体声波谐振器示意性俯视图和1B-1B向的截面图；
图7为根据本发明的一个示例性实施例的体声波谐振器的示意性截面图；
图8为根据本发明的一个示例性实施例的体声波谐振器的示意性截面图。
具体实施方式
下面通过实施例，并结合附图，对本发明的技术方案作进一步具体的说明。在说明书中，相同或相似的附图标号指示相同或相似的部件。下述参照附图对本发明实施方式的说明旨在对本发明的总体发明构思进行解释，而不应当理解为对本发明的一种限制。
本发明在谐振器有效区域的边缘形成断裂结构，由于断裂结构的声阻抗和谐振器有效区域的声阻抗不匹配，从而在边缘处将声波反射回谐振器内，有效阻止了谐振器内能量的泄露。
下面参照附图1-8描述根据本发明的实施例的体声波谐振器。
图1A为根据本发明的一个示例性实施例的薄膜体声波谐振器的俯视图。参见图1A，FBAR包括底电极105、压电层107、顶电极109、钝化层111以及位于顶电极109和其电极连接处台阶上方的钝化层中具有一断裂结构113。
在本发明的所有实施例中，压电层材料掺杂稀土元素。
典型的压电材料为氮化铝(AlN)，其为纤锌矿结构即六方晶系，极化轴方向为 (0001)。
掺杂的稀土元素包括： 镧(La)、 铈(Ce)、 镨(Pr)、 钕(Nd)、钷(Pm)、钐(Sm)、铕(Eu)、钆(Gd)、铽(Tb)、镝(Dy)、 钬(Ho)、铒(Er)、铥(Tm)、镱(Yb)、镥(Lu)，以及钇(Y)和钪(Sc)中的一种或者任意多种。在可选的实施例中，掺杂的稀土元素包括钪(Sc)。
对于压电材料为氮化铝(AlN)，掺杂的方式可以为一种或者任意两种稀土元素X和/或Y替换AlN晶体结构中的Al原子，形成Al 1-aX aN或Al 1-a-bX aY bN结构，其中X、Y代表上述稀土元素中的任意两种元素，a、b代表掺杂原子X、Y的含量。可选的，稀土元素X或Y的原子分数可以为0.5％-30％，其中掺杂的稀土元素X与Y的含量可以相同也可以不同。
以上对于掺杂的描述可以适用于本发明的所有实施例。
图1B为沿着图1A中1B-1B向所取的截面图。如图1B所示，谐振器在厚度方向上依次包括基底101；声学镜103，此声学镜位于基底的上表面或嵌于基底的内部，在图1B中声学镜为嵌入基底中的空腔所构成，但是任何其它的声学镜结构如布拉格反射器也同样适用；底电极105；压电层107，压电层掺杂任意两种稀土元素；顶电极109；钝化层111。其中钝化层能够起到对电极保护的作用，防止材料在谐振器表面的吸附，消除或减轻由于周围空气或潮湿环境影响而导致器件的氧化、腐蚀，从而使得谐振器频率发生偏移；同时还可以通过对钝化层进行处理，能够起到对谐振器频率进行微调的作用；并且钝化层的存在可以降低对谐振器密闭封装的要求，使器件制作的成本降低。
如图1A和1B所示，位于顶电极和其电极连接处台阶上方的钝化层中具有一断裂结构113，其断裂的方式只有部分(即没有完全断开)。断裂结构113的截面形状除了为图1C中的圆弧形状外，还可以为图1D中的倾斜形状、图1E中的阶梯形状和图1F中的扇形形状等其他形状，断裂结构有固定的宽度w和深度h。在可选的实施例中，断裂结构的深度小于钝化层的厚度，例如为钝化层厚度的5％-30％，其典型的w范围在0.1-10μm，h的深度在
Figure PCTCN2019113999-appb-000004
在本发明中，对于没有完全断裂的准断裂结构，w可以为0.1μm、5μm、10μm；h可以为
Figure PCTCN2019113999-appb-000005
断裂结构可通过湿法刻蚀或者干法刻蚀等类似的工艺获得，通过控制湿法刻蚀的 时间以及调控药液的比例来控制断裂结构的宽度和深度，或者通过控制干法刻蚀的时间、功率以及刻蚀气体的流量与比例来控制断裂结构的宽度和深度。
声学镜103、底电极105、压电层107、顶电极109在厚度方向重叠的区域为谐振器的有效区域，具有第一声阻抗，在钝化层111的断裂结构113中具有第二声阻抗。由于在钝化层111的断裂结构113中的第二声阻抗与第一声阻抗不匹配，同时由于断裂结构中具有一定的深度，声波会在断裂结构处形成局部振荡，通过声波在局部振荡区域多次反射叠加形成强反射，能够进一步增加不匹配程度，这样会使得声波在有效区域的边界处传输不连续，因此在有效区域的边界处，一部分声能就会耦合且反射到有效激励区域中，并且转换成与压电层表面垂直的活塞声波模式，从而使得谐振器的Q值得到提高。但是断裂结构的存在在提升谐振器Q值的同时，会带来Kt 2下降的问题，为了弥补这一缺陷，我们通过对压电层材料进行掺杂稀土元素，用以提高其Kt 2，来弥补断裂结构的不足之处。对于特定的声波波长，可以选择断裂结构的形状、深度和宽度，以调整形成局部振荡的能力和程度。
图2A和图2B分别为根据本发明的一个示例性实施例的体声波谐振器示意性俯视图和1B-1B向的截面图。下面参照图2A和2B说明体声波谐振器的另一个示例性实施例。
如图2A所示，FBAR包括底电极205、压电层207、顶电极209、钝化层211以及位于顶电极和其电极连接处台阶上方的钝化层中具有一断裂结构213。
图2B所示的压电谐振器结构与图1B所示的实施例结构类似，它们都是沿着俯视图1B-1B所取的截面图。不同之处在于位于顶电极和其电极连接处台阶上方的钝化层的断裂结构213。断裂结构213的截面形状可以为图1C中的圆弧状，也可以为图1D中的倾斜形状、图1E中的阶梯形状和图1F中的扇形形状等其他形状，断裂结构断裂的方式为断裂到底部的顶电极，深度较深。断裂结构213的深度与钝化层的厚度一样，典型的w范围在0.1-10μm，深度h在
Figure PCTCN2019113999-appb-000006
在本发明中，对于完全断裂的断裂结构，w可以为0.1μm、5μm、10μm；h可以为
Figure PCTCN2019113999-appb-000007
由于断裂结构具有的深度更深，能够进一步提高在钝化层断裂结构的第二声阻抗与第一声阻抗不匹配程度，会使得声波在边界处传输不连续性增强，因此在有效区域的边界处，就会有更多的声能耦合且反射到有效激励区域中，并且转换成与压电层表 面垂直的活塞声波模式，从而使得谐振器的Q值进一步提高。但是断裂结构的存在在提升谐振器Q值的同时，会带来Kt 2下降的问题，为了弥补这一缺陷，通过对压电层材料进行掺杂稀土元素，用以提高其Kt 2，来弥补断裂结构的不足之处。
图3A和图3B分别为根据本发明的一个示例性实施例的体声波谐振器示意性俯视图和1B-1B向的截面图。下面参照图3A和3B说明体声波谐振器的再一个示例性实施例。
如图3A所示，FBAR包括底电极305、压电层307、顶电极309、钝化层311以及位于顶电极和其电极连接处台阶上方的钝化层中具有一断裂结构313和315。
在图3B所示的压电谐振器结构与图1B所示的实施例结构类似，它们都是沿着俯视图1B-1B所取的截面图。不同之处在于位于顶电极和其电极连接处台阶上方的钝化层的断裂结构，其断裂部分包含313和315，断裂结构的截面形状可以为图1C中的圆弧状，也可以为图1D中的倾斜形状、图1E中的阶梯形状和图1F中的扇形形状等其他形状，断裂方式为多处位置包括但不限于两处，断裂深度较浅。断裂部分具有两个固定宽度w1和w2以及两个断裂深度h1和h2。在可选的实施例中，断裂结构的深度小于钝化层的厚度，例如为钝化层厚度的5％-30％，其典型的w1和w2范围在0.1-10μm，h1和h2深度在
Figure PCTCN2019113999-appb-000008
这样在保证谐振器Q值进一步提高的同时，使得钝化层全面覆盖住谐振的电极部分，从而使得钝化层对谐振器的保护更为全面，能够有效防止材料在谐振器表面的吸附，消除或减轻由于周围空气或潮湿环境影响而导致器件的氧化、腐蚀，从而使得谐振器频率发生偏移。但是断裂结构的存在在提升谐振器Q值的同时，会带来Kt 2下降的问题，为了弥补这一缺陷，通过对压电层材料进行掺杂稀土元素，用以提高其Kt 2，来弥补断裂结构的不足之处。
需要指出的是，在本发明中，掺杂的稀土元素可以是一种，也可以是两种或者更多种。
基于以上，本发明提出了一种体声波谐振器，包括：基底；声学镜；底电极，设置在基底上方；顶电极，与所述底电极对置，所述顶电极具有主体部以及与主体部连接的连接部；压电层，设置在底电极上方以及底电极与顶电极之间，压电层内掺杂有稀土元素；和钝化层，设置在顶电极上方，其中：声学镜、底电极、压电层、顶电极在基底的厚度方向重叠的区域为谐振器的有效区域，所述钝化层邻近所述有效区域的边界、在所述连接部上方设置有至少一个第一断裂结构。
在上面的图1B、图2B和图3B中，连接部可为顶电极和其电极引线连接处，体现为倾斜面。断裂结构设置在所述倾斜面处。
需要专门指出的是，在本发明中，在连接部上方设置断裂结构，不仅包括断裂结构仅设置在连接部正上方(在横向方向上，位于连接部的两个竖向边界之间)，也包括断裂结构设置在连接部斜上方的情况。
在本发明中，断裂结构设置在倾斜面处，不仅包括设置在倾斜面所在范围内的情况，也包括设置在倾斜面附近的情形。
虽然没有示出，所述连接部也可为水平的连接部。
需要指出的是，在钝化层中，断裂结构除了设置在连接部上方外，还可以设置在其他部位。
在本发明中，电极组成材料可以是金(Au)、钨(W)、钼(Mo)、铂(Pt)，钌(Ru)、铱(Ir)、钛钨(TiW)、铝(Al)、钛(Ti)等类似金属。
在本发明中，压电层材料可以为氮化铝(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)等材料。
在本发明中，钝化层材料可以为氮化铝(AlN)、碳化硅(SiC)、氧化铝(Al 2O 3)、氧化硅(SiO 2)、氮化硅(Si 3N 4)或它们的组合等材料。
图7为根据本发明的一个示例性实施例的体声波谐振器的示意性截面图。如图7所示，谐振器在厚度方向上依次包括基底701；声学镜703，此声学镜位于基底的上表面或嵌于基底的内部，在图7中声学镜为嵌入基底中的空腔所构成，但是任何其它的声学镜结构如布拉格反射器也同样适用；底电极705；压电层707，压电层内掺杂有稀土元素；顶电极709，包含两部分即主体部和连接部，其中连接部为桥翼结构，在顶电极的连接部和压电层之间为空气隙；钝化层711，包含在台阶处的断裂结构715和713，断裂结构的截面形状可以为图1C中的圆弧状，也可以为图1D中的倾斜形状、图1E中的阶梯形状和图1F中的扇形形状等其他形状，其断裂方式为部分断裂，并且具有固定的宽度w1、w2和断裂深度h1、h2。在可选的实施例中，断裂结构的深度小于钝化层的厚度，例如为钝化层厚度的5％-30％，其典型的w1和w2的范围在0.1-10μm，h1和h2深度在
Figure PCTCN2019113999-appb-000009
在桥翼结构和断裂结构处，由于空气隙和断裂结构的存在使其声阻抗与谐振器的有效区域内声阻抗不匹配，会使得声波在边界处传输不连续，因此在有效区域的边界 处，一部分声能就会耦合且反射到有效激励区域中，并且转换成与压电层表面垂直的活塞声波模式，从而使得谐振器的Q值得到提高。但是桥翼结构和断裂结构的存在在提升谐振器Q值的同时，会带来Kt 2下降的问题，为了弥补这一缺陷，通过对压电层材料进行掺杂稀土元素，用以提高其Kt 2，来弥补断裂结构的不足之处。
图8为根据本发明的一个示例性实施例的体声波谐振器的示意性截面图。如图8所示，谐振器在厚度方向上依次包括基底801；声学镜803，此声学镜位于基底的上表面或嵌于基底的内部，在图8中声学镜为嵌入基底中的空腔所构成，但是任何其它的声学镜结构如布拉格反射器也同样适用；底电极805；压电层807，压电层内掺杂有稀土元素；顶电极809，包含主体部和连接部，其中连接部为桥部结构，在顶电极的连接部和压电层之间为空气隙；钝化层811，包含在台阶处的断裂结构815和813。
因此，在例如图8的示例中，所述连接部形成桥部结构，桥部结构与压电层之间形成空气隙，所述倾斜面包括所述桥部结构的邻近所述边界的第一倾斜面以及邻近顶电极引线的第二倾斜面，断裂结构设置在所述第一倾斜面处，可选的，断裂结构也设置在所述第二倾斜面处。
断裂结构的截面形状可以为图1C中的圆弧状，也可以为图1D中的倾斜形状、图1E中的阶梯形状和图1F中的扇形形状等其他形状，其断裂方式为部分断裂，并且具有固定的宽度w1、w2和断裂深度h1、h2。在可选的实施例中，断裂结构的深度小于钝化层的厚度，例如为钝化层厚度的5％-30％，其典型的w1和w2的范围在0.1-10μm，h1和h2深度在
Figure PCTCN2019113999-appb-000010
在桥部结构和断裂结构处，由于空气隙和断裂结构的存在，使其声阻抗与谐振器的有效区域内声阻抗不匹配，会使得声波在有效区域的边界处传输不连续，因此在有效区域的边界处，一部分声能就会耦合且反射到有效激励区域中，并且转换成与压电层表面垂直的活塞声波模式，从而使得谐振器的Q值得到提高。但是桥部结构和断裂结构的存在在提升谐振器Q值的同时，会带来Kt 2下降的问题，为了弥补这一缺陷，通过对压电层材料进行掺杂稀土元素，用以提高其Kt 2，来弥补断裂结构的不足之处。
图4A和图4B分别为根据本发明的一个示例性实施例的体声波谐振器示意性俯视图和1B-1B向的截面图。
如图4A所示，FBAR包括底电极405、压电层407、顶电极409、钝化层411以及在顶电极与压电层之间位于顶电极内部的断裂结构413和位于顶电极和其电极连接处 台阶(对应于连接部)上方的钝化层中具有一断裂结构415。
如图4B所示，谐振器在厚度方向上依次包括基底401；声学镜403，此声学镜位于基底的上表面或嵌于基底的内部，在图4B中声学镜为嵌入基底中的空腔所构成，但是任何其它的声学镜结构如布拉格反射器也同样适用；底电极407；压电层407，压电层内掺杂有稀土元素；顶电极409；钝化层411；以及在顶电极与压电层之间位于顶电极内部的断裂结构413和位于顶电极和其电极连接处台阶(对应于连接部)上方的钝化层中具有的断裂结构415。
断裂结构413和415的截面形状可以为图1C中的圆弧状，也可以为图1D中的倾斜形状、图1E中的阶梯形状和图1F中的扇形形状等其他形状，有固定的宽度w1、w2和断裂深度h1、h2。在可选的实施例中，断裂结构的宽度w2与谐振器有效区域横向宽度之间有一比例范围在1％-10％，断裂结构的深度与压电层的厚度之间也有比例范围在1％-15％之间，其典型的w1和w2的范围在0.1-10μm，h1和h2深度在
Figure PCTCN2019113999-appb-000011
由于断裂结构的深度较浅，所以谐振器的机械强度则较强。
断裂结构可通过湿法刻蚀或者干法刻蚀等类似的工艺获得，通过控制湿法刻蚀的时间以及调控药液的比例来控制断裂结构的宽度和深度，或者通过控制干法刻蚀的时间、功率以及刻蚀气体的流量与比例来控制断裂结构的宽度和深度。
在图4A和4B的实施例中，声学镜、底电极、压电层、顶电极在厚度方向重叠的区域为谐振器的有效区域，具有第一声阻抗，在钝化层的断裂结构415中具有第二声阻抗，在压电层中的断裂结构413中具有第三声阻抗。由于在钝化层断裂结构的第二声阻抗和压电层中断裂结构的第三声阻抗与谐振器有效区域的第一声阻抗不匹配，会使得声波在边界处传输不连续，因此在边界处，一部分声能就会耦合且反射到有效激励区域中，并且转换成与压电层表面垂直的活塞声波模式，从而使得谐振器的Q值得到提高。同时由于断裂结构的深度较浅，不会对压电层产生破坏，从而不会影响谐振器的主模模式，还能够在有效提升谐振器机械强度的同时提高谐振器的Q值。但是断裂结构的存在在提升谐振器Q值的同时，会带来Kt 2下降的问题，为了弥补这一缺陷，通过对压电层材料进行掺杂稀土元素，用以提高其Kt 2，来弥补断裂结构的不足之处。
图5A和图5B分别为根据本发明的一个示例性实施例的体声波谐振器示意性俯视图和1B-1B向的截面图。
如图5A所示，FBAR包括底电极505、压电层507、顶电极509、钝化层511以及 在顶电极与压电层之间位于顶电极外部的断裂结构513和位于顶电极和其电极连接处台阶(对应于连接部)上方的钝化层中具有一断裂结构515。
在图5B所示的压电谐振器结构与图4B所示的实施例结构类似，它们都是沿着俯视图1B-1B所取的截面图，不同之处在于：在图4B中，断裂结构处于顶电极的下方或者为顶电极覆盖，或者是处于有效区域的边界的横向内侧，而在图5B中，压电层与顶电极之间的断裂结构位于顶电极的外部，或者是处于有效区域的边界的横向外侧。在此实施例中，断裂结构513和515的截面形状可以为图1C中的圆弧状，也可以为图1D中的倾斜形状、图1E中的阶梯形状和图1F中的扇形形状等其他形状，有具有固定的宽度w1、w2和断裂深度h1、h2。在可选的实施例中，断裂结构的宽度w2与谐振器有效区域横向宽度之间有一比例范围在1％-10％，断裂结构的深度与压电层的厚度之间也有比例范围在1％-15％之间，在进一步的实施例中，w1和w2的范围在0.1-10μm，h1和h2深度在
Figure PCTCN2019113999-appb-000012
由于在压电层上的断裂结构的深度较浅，所以谐振器的机械强度则较强，同时由于断裂结构的深度较浅，不会对压电层产生破坏，从而不会影响谐振器的主模模式。
此外，在钝化层断裂结构515的第二声阻抗和压电层中断裂结构513的第三声阻抗与谐振器有效区域的第一声阻抗不匹配，会使得声波在边界处传输不连续，因此在有效区域的边界处，一部分声能就会耦合且反射到有效激励区域中，并且转换成与压电层表面垂直的活塞声波模式，从而使得谐振器的Q值得到提高。但是断裂结构的存在在提升谐振器Q值的同时，会带来Kt 2下降的问题，为了弥补这一缺陷，我们通过对压电层材料进行掺杂稀土元素，用以提高其Kt 2，来弥补断裂结构的不足之处。
图6A和图6B分别为根据本发明的一个示例性实施例的体声波谐振器示意性俯视图和1B-1B向的截面图。
如图6A所示，FBAR包括底电极605、压电层607、顶电极609、钝化层611以及在顶电极与压电层之间位于顶电极内部具有多处断裂位置的断裂结构615和617，其断裂方式为多处位置包括但不限于两处，其断裂深度较浅。
在图6B所示的压电谐振器结构与图4B所示的实施例结构类似，它们都是沿着俯视图1B-1B所取的截面图，不同之处在于：
在顶电极与压电层之间的断裂结构位于顶电极的内部(被顶电极覆盖)且断裂结构包含两部分即615和617，其断裂方式为多处位置包括但不限于两处。在顶电极与 压电层之间的断裂结构的断裂深度较浅。在此实施例中，断裂结构613、615和617的截面形状可以为图1C中的圆弧状，也可以为图1D中的倾斜形状、图1E中的阶梯形状和图1F中的扇形形状等其他形状。在图6B的实施例中，断裂结构具有固定的宽度w1、w2、w3和断裂深度h1、h2、h3，可选的，断裂结构的宽度w2和w3与谐振器有效区域横向宽度之间有一比例范围在1％-10％，断裂结构的深度与压电层的厚度之间也有比例范围在1％-15％之间，更进一步的，w1、w2和w3的范围在0.1-10μm，h1、h2和h3深度在
Figure PCTCN2019113999-appb-000013
左右。
由于顶电极与压电层之间的断裂结构的深度较浅，所以谐振器的机械强度则较强，同时由于断裂结构的深度较浅，不会对压电层产生破坏，从而不会影响谐振器的主模模式。
而且，由于在压电层内的断裂结构为多处，使得断裂结构中的声阻抗与谐振器有效区域中的声阻抗不匹配度进一步增加，从而声波在边界处传输不连续会进一步增强，因此在有效区域的边界处，会有更多的声能耦合且反射到有效激励区域中，并且转换成与压电层表面垂直的活塞声波模式，从而使得谐振器的Q值进一步提高。但是断裂结构的存在在提升谐振器Q值的同时，会带来Kt 2下降的问题，为了弥补这一缺陷，通过对压电层材料进行掺杂稀土元素，用以提高其Kt 2，来弥补断裂结构的不足之处。
在本发明中，提到的数值范围除了可以为端点值之外，还可以为端点值之间的中值或者其他值，均在本发明的保护范围之内。
本发明的实施例还涉及一种滤波器，包括上述的体声波谐振器。
本发明的实施例也涉及一种电子设备，包括上述的滤波器。需要指出的是，这里的电子设备，包括但不限于射频前端、滤波放大模块等中间产品，以及手机、WIFI、无人机等终端产品。
在本发明中，电极组成材料可以是金(Au)、钨(W)、钼(Mo)、铂(Pt)，钌(Ru)、铱(Ir)、钛钨(TiW)、铝(Al)、钛(Ti)等类似金属形成。
在本发明中，钝化层材料可以为氮化铝(AlN)、碳化硅(SiC)、氧化铝(Al2O3)、氧化硅(SiO2)、氮化硅(Si3N4)或它们的组合等材料。
尽管已经示出和描述了本发明的实施例，对于本领域的普通技术人员而言，可以理解在不脱离本发明的原理和精神的情况下可以对这些实施例进行变化，本发明的范围由所附权利要求及其等同物限定。

Claims (24)

  1. 一种体声波谐振器，包括：
    基底；
    声学镜；
    底电极，设置在基底上方；
    顶电极，与所述底电极对置，所述顶电极具有主体部以及与主体部连接的连接部；
    压电层，设置在底电极上方以及底电极与顶电极之间；和
    钝化层，设置在顶电极上方，
    其中：
    声学镜、底电极、压电层、顶电极在基底的厚度方向重叠的区域为谐振器的有效区域，所述钝化层邻近所述有效区域的边界、在所述连接部上方设置有至少一个第一断裂结构；且
    所述压电层内掺杂有稀土元素。
  2. 根据权利要求1所述的谐振器，其中：
    所述连接部具有倾斜面，所述第一断裂结构设置在所述倾斜面处。
  3. 根据权利要求2所述的谐振器，其中：
    所述连接部形成桥部结构，桥部结构与压电层之间形成空气隙，所述倾斜面包括所述桥部结构的邻近所述边界的第一倾斜面以及邻近顶电极引线的第二倾斜面，所述第一断裂结构设置在所述第一倾斜面处。
  4. 根据权利要求3所述的谐振器，其中：
    所述钝化层还包括设置在所述第二倾斜面处的至少一个第二断裂结构。
  5. 根据权利要求1所述的谐振器，其中：
    所述连接部为水平的连接部。
  6. 根据权利要求1所述的谐振器，其中：
    所述顶电极在与所述连接部相对的一侧还设置有桥翼结构，所述桥翼结构具有桥翼斜面，所述桥翼结构与压电层之间形成空气隙。
  7. 根据权利要求6所述的谐振器，其中：
    所述钝化层还包括设置在所述桥翼斜面上方的至少一个第三断裂结构。
  8. 根据权利要求1-7中任一项所述的谐振器，其中：
    所述断裂结构的深度小于所述钝化层的厚度。
  9. 根据权利要求8所述的谐振器，其中：
    所述断裂结构的深度为所述钝化层的厚度的5％-30％。
  10. 根据权利要求9所述的谐振器，其中：
    所述断裂结构的深度的取值范围为
    Figure PCTCN2019113999-appb-100001
  11. 根据权利要求1-7中任一项所述的谐振器，其中：
    至少部分所述断裂结构的深度等于所述钝化层的厚度。
  12. 根据权利要求11所述的谐振器，其中：
    所述钝化层的厚度的取值范围为
    Figure PCTCN2019113999-appb-100002
  13. 根据权利要求1-12中任一项所述的谐振器，其中：
    在所述顶电极的下方或者在所述顶电极的横向外侧，邻近所述有效区域的边界在所述压电层中设置有至少一个第四断裂结构。
  14. 根据权利要求13所述的谐振器，其中：
    所述第四断裂结构的宽度为所述有效区域的横向宽度的1-10％。
  15. 根据权利要求13或14所述的谐振器，其中：
    所述第四断裂结构的深度为所述压电层的厚度的1-15％。
  16. 根据权利要求15所述的谐振器，其中：
    所述第四断裂结构的深度的取值范围为
    Figure PCTCN2019113999-appb-100003
  17. 根据权利要求1-16中任一项所述的谐振器，其中：
    所述断裂结构的宽度的取值范围为0.1-10μm。
  18. 根据权利要求1-17中任一项所述的谐振器，其中：
    所述断裂结构的截面形状为圆弧状、倾斜状、阶梯状、扇形状中的一种。
  19. 根据权利要求1所述的谐振器，其中：
    掺杂的稀土元素包括镧(La)、铈(Ce)、镨(Pr)、钕(Nd)、钷(Pm)、钐(Sm)、铕(Eu)、钆(Gd)、铽(Tb)、镝(Dy)、钬(Ho)、铒(Er)、铥(Tm)、镱(Yb)、镥(Lu)、钇(Y)和钪(Sc)中的一种或者任意多种元素。
  20. 根据权利要求19所述的谐振器，其中：
    所述压电层材料为氮化铝(ALN)，掺杂后形成Al 1-aX aN或Al 1-a-bX aY bN结构，其中X、Y代表上述稀土元素中的任意两种元素，a、b分别代表掺杂元素X、Y的含量。
  21. 根据权利要求20所述的谐振器，其中：
    掺杂元素X或Y的原子分数均为0.5％-30％。
  22. 根据权利要求19所述的谐振器，其中：
    掺杂的稀土元素包括钪(Sc)。
  23. 一种滤波器，包括根据权利要求1-22中任一项所述的体声波谐振器。
  24. 一种电子设备，包括根据权利要求23所述的滤波器。
PCT/CN2019/113999 2018-11-14 2019-10-29 体声波谐振器、滤波器和电子设备 WO2020098480A1 (zh)

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