WO2020125354A1 - Bulk acoustic wave resonator with discrete structure, filter and electronic device - Google Patents

Bulk acoustic wave resonator with discrete structure, filter and electronic device Download PDF

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Publication number
WO2020125354A1
WO2020125354A1 PCT/CN2019/121095 CN2019121095W WO2020125354A1 WO 2020125354 A1 WO2020125354 A1 WO 2020125354A1 CN 2019121095 W CN2019121095 W CN 2019121095W WO 2020125354 A1 WO2020125354 A1 WO 2020125354A1
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discrete
resonator
resonator according
bulk acoustic
discrete structure
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PCT/CN2019/121095
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French (fr)
Chinese (zh)
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杨清瑞
庞慰
张孟伦
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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 WO2020125354A1 publication Critical patent/WO2020125354A1/en

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
    • 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
    • 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
    • H03H9/46—Filters
    • H03H9/54—Filters comprising resonators of piezo-electric or electrostrictive material

Definitions

  • Embodiments of the present invention relate to the field of semiconductors, and particularly to a bulk acoustic wave resonator, a filter with the resonator, an electronic device with the filter, and a method of increasing the parallel impedance of the resonator.
  • Thin film bulk acoustic resonator (abbreviated as FBAR) has the advantages of high resonance frequency, high quality factor, high power endurance, low power consumption, low price, etc.
  • the bulk acoustic wave filter and duplexer are formed by cascading thin film bulk acoustic resonator It has the advantages of high operating frequency, low insertion loss, high steep drop, high power endurance, etc. In recent years, it is generally considered to be the best solution to replace surface acoustic wave devices to solve the high-density frequency band duplexer of wireless communication.
  • FIG. 1A The top view structure of the thin film piezoelectric bulk acoustic resonator is shown in FIG. 1A, and includes a bottom electrode 120, a piezoelectric layer 130, a top electrode 140, and an acoustic wave reflection structure 110 located below the bottom electrode.
  • FIG. 1B is a cross-sectional view along AA′ in FIG. 1A.
  • the resonator body has a sandwich structure. The principle is to use the inverse piezoelectric effect of the piezoelectric thin film material to generate a certain frequency for the external electrical excitation. resonance.
  • Bulk acoustic wave resonators generally have two resonance frequencies.
  • the frequency point with the smallest impedance is defined as the series resonance frequency fs
  • the corresponding impedance is the series impedance Rs
  • the frequency point with the largest impedance is the parallel resonance frequency fp
  • the corresponding impedance is the parallel impedance Rp.
  • the electromechanical coupling coefficient measures the piezoelectric conversion efficiency in the resonator.
  • the series resonance frequency of the resonator determines the center frequency of the filter, and the effective electromechanical coupling coefficient of the resonator determines the maximum bandwidth that the filter can achieve.
  • the series and parallel impedances of the resonator determine the passband insertion loss and return Wave loss.
  • the thin film bulk acoustic resonator only excites the main vibration mode that expands in the longitudinal direction, as shown by the arrows in FIG. 1B.
  • a parasitic mode of lateral propagation will be generated in the resonator, called Lamb wave, and part of the energy of the main vibration mode will be coupled into the Lamb wave.
  • This kind of Lamb wave will partially leak into the substrate from both sides of the resonator, resulting in resonator energy loss.
  • the electrical performance of the resonator is represented by the parallel impedance (parallel impedance Rp) or the quality factor of the parallel resonance frequency ( Qp) decreases.
  • the invention proposes a technical solution for improving the parallel impedance of a bulk acoustic wave resonator by setting a discrete structure.
  • a bulk acoustic wave resonator including: a substrate; an acoustic mirror; a bottom electrode provided on the upper side of the substrate; a top electrode; and a piezoelectric layer provided on the upper side of the bottom electrode and Between the bottom electrode and the top electrode, where: 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 resonator further includes at least one discrete structure, the The discrete structures are located inside the effective area and are arranged in strips along the edges of the effective area. Each discrete structure includes multiple discrete units.
  • the discrete structure is an annular discrete structure. Further, the lateral distance between the discrete structure and the edge of the effective area remains unchanged.
  • the at least one discrete structure includes a discrete structure. Further, the discrete structure is provided on the upper side of the top electrode.
  • the discrete unit is a protrusion.
  • the discrete unit is a depression.
  • the pitch between two adjacent discrete units is 1 ⁇ m-10 ⁇ m, or an integer multiple of the S1 mode Lamb wave wavelength at the parallel resonance frequency of the resonator.
  • the radial and/or lateral dimensions of a single discrete unit are 0.5 ⁇ m-6 ⁇ m, or one quarter of the wavelength of the S1 mode Lamb wave or its odd multiple at the parallel resonance frequency of the resonator .
  • the distance of the discrete structure from the edge of the effective area is 0.
  • the at least one discrete structure includes at least two discrete structures, and the at least two discrete structures are spaced apart in the radial direction.
  • the at least two discrete structures include convex discrete structures composed of protrusions and/or concave discrete structures composed of depressions.
  • the pitch of two discrete structures adjacent in the radial direction in the radial direction is 1 ⁇ m-10 ⁇ m, or an integer multiple of the S1 mode Lamb wave wavelength at the parallel resonance frequency of the bulk acoustic wave resonator.
  • the adjacent discrete units of each discrete structure have a pitch in the lateral direction of 1 ⁇ m-10 ⁇ m, or an integer multiple of the S1 mode Lamb wave wavelength at the parallel resonance frequency of the bulk acoustic wave resonator.
  • the radial dimension and/or lateral dimension of a single discrete unit is 0.5 ⁇ m-6 ⁇ m, or one quarter of the wavelength of the S1 mode Lamb wave at the parallel resonance frequency of the bulk acoustic wave resonator, or Odd times.
  • the lateral distance between a discrete unit of one discrete structure and a discrete unit adjacent to it in the other discrete structure is 0-5 ⁇ m, or It is a quarter of the wavelength of the S1 mode Lamb wave or its integer multiple at the parallel resonance frequency of the bulk acoustic wave resonator.
  • the radial distance of the outer discrete structure from the edge of the effective area is 0.
  • the area of the effective area of the resonator occupied by the discrete structure does not exceed 20% of the total area of the effective area of the resonator, and optionally, does not exceed 10%.
  • the discrete structure is provided on the piezoelectric layer, the top electrode, or the bottom electrode; or the resonator is further provided with a passivation layer covering the top electrode, and the discrete structure is provided on the passivation layer Underside.
  • a filter including the bulk acoustic wave resonator described above.
  • an electronic device including the above-mentioned filter or the above-mentioned resonator.
  • the invention also relates to a method for increasing the parallel impedance of a bulk acoustic wave resonator, comprising the steps of forming at least one annular discrete structure on the upper side of the top electrode of the resonator around the effective area of the resonator.
  • FIG. 1A is a schematic top view of a bulk acoustic wave resonator in the prior art
  • Fig. 1B is a cross-sectional view taken along line A-A' in Fig. 1A;
  • FIG. 2A is a schematic top view of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention, in which only one annular discrete structure is provided;
  • FIG. 2B is a cross-sectional view of the bulk acoustic wave resonator in FIG. 2A along the B-B' direction according to an exemplary embodiment of the present invention
  • FIG. 2C is a cross-sectional view of the bulk acoustic wave resonator in FIG. 2A along the B-B' direction according to an exemplary embodiment of the present invention
  • FIG. 2D is a schematic diagram of the size of the discrete structure in FIG. 2A;
  • 3A is a schematic top view of a bulk acoustic wave resonator according to another exemplary embodiment of the present invention, in which two annular discrete structures are provided;
  • FIG. 3B is a cross-sectional view of the bulk acoustic wave resonator in FIG. 3A along the C-C' direction according to an exemplary embodiment of the present invention
  • 3C is a cross-sectional view of the bulk acoustic wave resonator in FIG. 3A along the C-C' direction according to an exemplary embodiment of the present invention
  • 3D is a cross-sectional view of the bulk acoustic wave resonator in FIG. 3A along the C-C' direction according to an exemplary embodiment of the present invention
  • 3E is a cross-sectional view of the bulk acoustic wave resonator in FIG. 3A along the C-C' direction according to an exemplary embodiment of the present invention
  • 3F is a schematic diagram of the size of the discrete structure in FIG. 3A;
  • FIG. 4A is a schematic top view of a bulk acoustic wave resonator according to another exemplary embodiment of the present invention, in which three annular discrete structures are provided;
  • FIG. 4B is a cross-sectional view of the bulk acoustic wave resonator in FIG. 4A along the D-D' direction according to an exemplary embodiment of the present invention
  • FIG. 4C is a cross-sectional view along the D-D' direction of the bulk acoustic wave resonator in FIG. 4A according to an exemplary embodiment of the present invention
  • 4D is a cross-sectional view of the bulk acoustic wave resonator in FIG. 4A along the D-D' direction according to an exemplary embodiment of the present invention
  • FIG. 4E is a cross-sectional view of the bulk acoustic wave resonator in FIG. 4A along the D-D' direction according to an exemplary embodiment of the present invention
  • FIG. 4F is a cross-sectional view of the bulk acoustic wave resonator in FIG. 4A along the D-D' direction according to an exemplary embodiment of the present invention
  • FIG. 5 is a schematic diagram of dimensions of a multi-turn discrete structure according to an exemplary embodiment of the present invention.
  • FIG. 6A is a schematic top view of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention, wherein the discrete structure is a single turn, and the discrete unit has a square cross section;
  • FIG. 6B is a cross-sectional view of the bulk acoustic wave resonator in FIG. 6A along the E-E' direction according to an exemplary embodiment of the present invention
  • FIG. 6C is a cross-sectional view of the bulk acoustic wave resonator in FIG. 6A along the E-E' direction according to an exemplary embodiment of the present invention
  • FIG. 7 is a schematic top view of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention, wherein the discrete structure is a double loop, and the discrete unit has a square cross section;
  • FIG. 8 is a schematic top view of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention, wherein the discrete structure is three turns, and the discrete unit has a square cross section;
  • Fig. 9 is the dispersion curve of the S1 mode at the parallel resonance frequency of the bulk acoustic wave resonator.
  • FIG. 2A is a schematic top view of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention
  • FIG. 2B is a cross section of the bulk acoustic wave resonator in FIG. 2A along the BB′ direction according to an exemplary embodiment of the present invention Figure.
  • FIG. 2A is a top view of a bulk acoustic wave resonator.
  • the resonator includes a bottom electrode 120, a piezoelectric layer 130, a top electrode 140, and a single-turn discrete ring structure 150 disposed along the edge of the effective area of the resonator.
  • the single discrete structure is arranged in a circular shape.
  • FIG. 2B a cross-sectional view of the bulk acoustic wave resonator taken along the top view B-B' of FIG. 2A.
  • the resonator includes a substrate 100 in the thickness direction; an acoustic mirror 110, which is located on the upper surface of the substrate or embedded inside the substrate.
  • the acoustic mirror is composed of a cavity embedded in the substrate, but any other Acoustic mirror structures such as a Bragg reflector layer are also suitable; the bottom electrode 120, the piezoelectric layer 130, the top electrode 140, and the single-circle discrete annular convex structure 150 disposed inside the edge of the top electrode.
  • inside of the top electrode edge includes the case where the discrete structure is spaced apart from the edge of the top electrode, and also includes the case where the discrete structure is directly provided at the edge or the distance from the edge is zero.
  • discrete units are composed of discrete units, such as individual depressions or protrusions.
  • first acoustic impedance in the effective area of the resonator, and a second acoustic impedance in the single-circle discrete annular structure 150. Since the first acoustic impedance does not match the second acoustic impedance, the laterally propagating acoustic wave at the electrode It is reflected back at the edge, reducing the loss of acoustic energy in the resonator, thus increasing the parallel resistance Rp value and corresponding Q value of the resonator.
  • the single-turn discrete annular structure 150 can also be made into a concave structure, and its cross-sectional view taken along the top view B-B' of FIG. 2A is shown in FIG. 2C.
  • L1 is the horizontal dimension of the discrete unit
  • S1 is the interval or space of the adjacent discrete unit
  • W1 is the longitudinal dimension of the discrete unit
  • P1 is the pitch of the adjacent discrete unit
  • D0 is the distance between the single-circle discrete ring structure and the resonator edge.
  • the size of the pitch P1 between two adjacent discrete units is 1.5 ⁇ m-10 ⁇ m, such as 1.5 ⁇ m, 8 ⁇ m, and 10 ⁇ m, or the S1 mode Lamb wave wavelength at the parallel resonance frequency of the resonator An integer multiple of ⁇ , for example, 1 times;
  • the longitudinal dimension W1 of the discrete unit is a quarter of the corresponding Lamb wave wavelength or an odd multiple thereof, and S1 in the figure is between adjacent discrete protrusions or depressions (ie, adjacent discrete units Between), as an optional example, is three-quarters of the wavelength of the corresponding Lamb wave;
  • the distance D0 of the discrete structure from the edge of the effective area can be selected as 0;
  • the lateral dimension and longitudinal direction of the discrete unit The dimensions are equal, that is, L1 is equal to W1; in an alternative embodiment, the radial and/or lateral dimensions of a single discrete unit are 0.5 ⁇ m-6 ⁇ m, or 1/4 of the S1 mode Lamb wave wavelength at the parallel resonance frequency
  • the Lamb wave wavelength ⁇ of the S1 mode at the parallel resonance frequency of the resonator is briefly explained below. As shown in Fig. 9, when the bulk acoustic wave resonator works, a lot of vibrations will be generated in the sandwich structure. If these vibrations are plotted as dispersion curves according to the relationship between their frequency (f) and wave number (k), a variety of Curves of modes, one of which is called S1 mode (the curves of the remaining modes are not shown in FIG. 9), which has a dispersion curve of the shape shown in FIG. 9, where the abscissa is the wave number and the ordinate is the vibration frequency. When the vibration frequency is the parallel resonance frequency f p , the corresponding wave number is k p , and the wavelength ⁇ of the S1 mode is defined by the following formula:
  • FIG. 3A is a top view of a bulk acoustic wave resonator.
  • the top electrode 140 of the resonator is provided with two rings of discrete ring structures: a first ring of discrete ring structures 160 and a second ring of discrete ring structures 162.
  • FIG. 3B it is a cross-sectional view of the bulk acoustic wave resonator taken along the top view C-C' of FIG. 3A.
  • the resonator includes a substrate 100 in the thickness direction; an acoustic mirror 110, which is located on the upper surface of the substrate or embedded inside the substrate.
  • the acoustic mirror is composed of a cavity embedded in the substrate, but any other Acoustic mirror structures such as Bragg reflectors are also suitable; bottom electrode 120, piezoelectric layer 130, top electrode 140, and first ring discrete ring raised structure 160 and second ring discrete ring raised structure disposed inside the top electrode edge 162.
  • first acoustic impedance in the effective area of the resonator, and a second acoustic impedance in the ring-shaped convex structure. Because the first acoustic impedance does not match the second acoustic impedance, the laterally propagating acoustic wave is at the edge of the electrode Being reflected back reduces the loss of acoustic energy in the resonator, thus increasing the parallel resistance Rp and Q of the resonator.
  • the first ring of discrete annular structures 160 and the second ring of discrete annular structures 162 can also all be made into concave structures, and the cross-sectional view taken along the top view C-C' of FIG. 3A is shown in FIG. 3C.
  • the first ring discrete ring structure 160 and the second ring discrete ring structure 162 can also be made into different structures, as shown in FIG. 3D, the first ring discrete ring structure 160 is a convex structure, and the second ring discrete ring structure 162 is a depression Or, as shown in FIG. 3E, the first ring of discrete annular structures 160 is a concave structure, and the second ring of discrete annular structures 162 is a convex structure.
  • L2 is the lateral dimension of the discrete elements of the second ring discrete ring structure.
  • S2 is the interval or space between the adjacent discrete elements of the second ring discrete ring structure.
  • W2 is the second The longitudinal dimension of the discrete elements of the discrete annular ring structure, P2 is the pitch of the adjacent discrete elements of the discrete annular ring structure of the second circle.
  • d1 is the horizontal pitch of the discrete units of the first ring discrete ring structure and the adjacent discrete units of the second ring discrete ring structure, and D1 is the interval between the first ring discrete ring structure and the second ring discrete ring structure.
  • P2 is equal to P1 and equal to the S1 mode Lamb wave wavelength at the parallel resonance frequency of the resonator
  • W2 and W1 are a quarter of the corresponding Lamb wave wavelength
  • S2 and S1 are the corresponding blue
  • D0 is
  • D1 is three quarters of the corresponding Lamb wave wavelength
  • d1 is 0 or one quarter or one half of the corresponding Lamb wave wavelength
  • L2 is equal to W2.
  • the radial distance W2+D1 of the center lines of two discrete structures can be defined as the pitch of two adjacent discrete structures in the radial direction.
  • the pitch may be 1 ⁇ m-10 ⁇ m, or an integer multiple of the S1 mode Lamb wave wavelength at the parallel resonance frequency of the bulk acoustic wave resonator.
  • FIG. 4A is a top view of a bulk acoustic wave resonator.
  • a first discrete ring structure 170 On the FBAR top electrode 140, three discrete ring structures are provided: a first discrete ring structure 170, a second discrete ring structure 172, and a third discrete ring structure 174.
  • FIG. 4B it is a cross-sectional view of the bulk acoustic wave resonator taken along the top view D-D' of FIG. 4A.
  • the resonator includes a substrate 100 in the thickness direction; an acoustic mirror 110, which is located on the upper surface of the substrate or embedded inside the substrate.
  • FIG. 4B it is a cross-sectional view of the bulk acoustic wave resonator taken along the top view D-D' of FIG. 4A.
  • the resonator includes a substrate 100 in the thickness direction; an acoustic mirror 110, which is located on the upper surface of the substrate or embedded inside the substrate.
  • the acoustic mirror is composed of a cavity embedded in the substrate, but any other Acoustic mirror structures such as the Bragg reflector layer are also suitable; the bottom electrode 120, the piezoelectric layer 130, the top electrode 140, and the first ring of discrete ring convex structures 170 and the second ring of discrete ring convex structures disposed inside the edge of the top electrode 172 and the third ring of discrete annular convex structures 174.
  • first acoustic impedance in the effective area of the resonator, and a second acoustic impedance in the ring-shaped convex structure. Because the first acoustic impedance does not match the second acoustic impedance, the laterally propagating acoustic wave is at the edge of the electrode Being reflected back reduces the loss of acoustic energy in the resonator, thus increasing the parallel resistance Rp and Q of the resonator.
  • the first ring discrete ring structure 170, the second ring discrete ring structure 172 and the third ring discrete ring structure 174 can also all be made into a concave structure, and the cross-sectional view taken along the top view DD' of FIG. 4A is shown in FIG. 4C Show.
  • the first ring discrete ring structure 170, the second ring discrete ring structure 172 and the third ring discrete ring structure 174 can also be made into different concave-convex structures, as shown in FIG. 4D, the first ring discrete ring structure 170 and the second ring discrete The ring structure 172 is a convex structure, and the third ring discrete ring structure 174 is a concave structure; or as shown in FIG. 4E, the first ring discrete ring structure 170 and the third ring discrete ring structure 174 are convex structures, and the second ring discrete The ring structure 172 is a concave structure; or as shown in FIG.
  • the first ring discrete ring structure 170 is a convex structure
  • the second ring discrete ring structure 172 and the third ring discrete ring structure 174 are concave structures.
  • only a part of the combination forms are shown in the drawings, and there may be other combinations of different forms, and the invention is not listed one by one.
  • Embodiment 3 lists a bulk acoustic wave resonator in which the top electrode is provided with a three-ring discrete ring structure, and four or more turns may also be provided.
  • Ln is the lateral dimension of the n-th discrete ring structure
  • Sn is the interval or space of adjacent discrete units of the n-th discrete ring structure
  • Wn is the n-th discrete
  • Pn is the pitch of the adjacent discrete units of the n-th discrete ring structure.
  • dn-1 is the horizontal pitch of a discrete element of the n-1th discrete ring structure and an adjacent discrete element of the nth discrete ring structure
  • Dn-1 is the discrete ring structure of the n-1th ring and the nth circle Discrete annular structure (in the radial or longitudinal direction) spacing.
  • Pn is equal and equal to the S1 mode Lamb wave wavelength at the parallel resonance frequency of the resonator
  • Wn is a quarter of the corresponding Lamb wave wavelength
  • Sn is a quarter of the corresponding Lamb wave wavelength Three
  • D0 is
  • Dn-1 is three quarters of the corresponding Lamb wave wavelength
  • dn-1 is 0 or one quarter or one half of the corresponding Lamb wave wavelength.
  • the size of the multiple discrete structures may be in the following form:
  • the pitch of two discrete structures adjacent in the radial direction in the radial direction is 1 ⁇ m-10 ⁇ m, or an integer multiple of the S1 mode Lamb wave wavelength at the parallel resonance frequency of the bulk acoustic wave resonator.
  • the pitch of the adjacent discrete units of each discrete structure in the lateral direction is 1 ⁇ m-10 ⁇ m, or an integer multiple of the S1 mode Lamb wave wavelength at the parallel resonance frequency of the bulk acoustic wave resonator.
  • the radial dimension and/or lateral dimension of a single discrete unit is 0.5 ⁇ m-6 ⁇ m, or a quarter of the wavelength of the S1 mode Lamb wave or an odd multiple thereof at the parallel resonance frequency of the bulk acoustic wave resonator.
  • a lateral pitch between a discrete unit of a discrete structure and a discrete unit adjacent thereto in another discrete structure 0-5 ⁇ m, or a quarter of the wavelength of the S1 mode Lamb wave or its integral multiple at the parallel resonance frequency of the bulk acoustic wave resonator.
  • the area of the effective area of the resonator occupied by the discrete ring structure does not exceed 20% of the total area of the effective area of the resonator, preferably less than 10%.
  • the longitudinal dimension of the discrete unit is the same as the lateral dimension, that is, Ln is equal to Wn.
  • the discrete ring structure on the top electrode of the thin film bulk acoustic resonance structure can also be made square, as shown in FIG. 6A.
  • 210 is a single-turn discrete ring structure.
  • FIG. 6B it is a cross-sectional view of the bulk acoustic wave resonator taken along the top view E-E' of FIG. 6A.
  • the resonator includes a substrate 100 in the thickness direction; an acoustic mirror 110, which is located on the upper surface of the substrate or embedded inside the substrate.
  • the acoustic mirror is composed of a cavity embedded in the substrate, but any other Acoustic mirror structures such as a Bragg reflector layer are also suitable; the bottom electrode 120, the piezoelectric layer 130, the top electrode 140, and the single-circle discrete annular structure 210 disposed inside the edge of the top electrode.
  • first acoustic impedance in the effective area of the resonator, and a second acoustic impedance in the ring-shaped convex structure. Because the first acoustic impedance does not match the second acoustic impedance, the laterally propagating acoustic wave is at the edge of the electrode Being reflected back reduces the loss of acoustic energy in the resonator, thus increasing the parallel resistance Rp and Q of the resonator.
  • the single-circle discrete annular structure 210 can also be made into a concave structure, and its cross-sectional view taken along the top view E-E' of FIG. 6A is shown in FIG. 6C.
  • Fig. 7 is a double-circle square discrete ring structure
  • Fig. 8 is a three-circle square discrete ring structure.
  • the size of the square structure of the cross section needs to meet the same size requirements as the protrusions or depressions of the circular cross section.
  • the cross-section of the discrete cells in the discrete ring structure can also have other shapes.
  • the discrete structure may be a metal or dielectric material, or the same material as the piezoelectric layer or electrode.
  • the dielectric material may be aluminum nitride, silicon dioxide, silicon nitride, or the like.
  • the metal may be gold (Au), tungsten (W), molybdenum (Mo), platinum (Pt), or the like.
  • the present invention proposes a bulk acoustic wave resonator, including:
  • the bottom electrode 120 is provided on the upper side of the substrate 100;
  • the piezoelectric layer 130 is provided on the upper side of the bottom electrode and between the bottom electrode and the top electrode,
  • the area where the acoustic mirror 110, the bottom electrode 120, the piezoelectric layer 130, and the top electrode 140 overlap in the thickness direction of the substrate 100 is the effective area of the resonator;
  • the resonator further includes at least one discrete structure 150 or 160 or 170.
  • the discrete structures extend in a strip shape inside the effective area, and each discrete structure includes a plurality of discrete cells.
  • the discrete unit here can be considered as a single protrusion or depression, for example.
  • this structure can cause impedance mismatch at the edge of the effective area, which in turn causes sound waves to be trapped at the boundary Reflect back into the effective excitation area, thus have the opportunity to convert to the main vibration mode, reduce the loss of energy in the resonator, and thus increase the parallel impedance Rp.
  • a discrete structure is processed on, for example, the top electrode at one or more edges of the effective area of the resonator.
  • sound waves leaking into the substrate can be effectively reflected, thereby Effectively increase the resonator parallel resistance Rp value.
  • the discrete structure is an annular discrete structure.
  • the discrete structure may also be a plurality of discrete structure segments that are spaced apart from each other and are arranged along the inside of the effective area.
  • the discrete structure segment may be one or more discrete structure segments disposed on one side or multiple sides of the effective area of the polygon shown in FIG. 2A.
  • the lateral distance between the discrete structure and the effective area remains unchanged.
  • the discrete structures are all formed on the top electrode.
  • the discrete structure may be provided on the lower or upper side of the piezoelectric layer; or the discrete structure may be provided on the lower side of the top electrode; or the discrete structure may be provided on the upper or lower side of the bottom electrode; or the resonator may also A passivation layer covering the top electrode is provided, the discrete structure is provided under the passivation layer, and so on.
  • the "upper side” in the orientation means the side away from the substrate in the thickness direction of the resonator, and the “lower side” means the side close to the substrate in the thickness direction of the resonator.
  • the 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 above-mentioned filter or resonator.
  • 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 present invention also proposes a method for increasing the parallel impedance of a bulk acoustic wave resonator, comprising the steps of forming at least one annular discrete structure on the upper side of the top electrode of the resonator around the effective area of the resonator.

Abstract

The present invention relates to a bulk acoustic wave resonator, which comprises: a substrate; an acoustic mirror; a bottom electrode, which is arranged on the upper side of the substrate; a top electrode; and a piezoelectric layer, which is arranged above the bottom electrode and between the bottom electrode and the top electrode, wherein: the area where the acoustic mirror, 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 resonator further comprises at least one discrete structure, the discrete structure is located inside the effective area, and extends in a strip shape along the edge of the effective area, and each discrete structure comprises a plurality of discrete units. The present invention further relates to a filter with the resonator, and an electronic device with the filter or resonator.

Description

带离散结构的体声波谐振器、滤波器和电子设备Bulk acoustic wave resonator, filter and electronic equipment with discrete structure 技术领域Technical field
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，一种具有该谐振器的滤波器，一种具有该滤波器的电子设备，以及一种提高谐振器的并联阻抗的方法。Embodiments of the present invention relate to the field of semiconductors, and particularly to a bulk acoustic wave resonator, a filter with the resonator, an electronic device with the filter, and a method of increasing the parallel impedance of the resonator.
背景技术Background technique
随着无线移动通讯技术的快速发展，体声波器件应用领域越来越广泛。薄膜体声波谐振器(简称FBAR)具有高谐振频率、高品质因数、高功率承受能力、低功耗、低价格等优点，体声波滤波器、双工器由薄膜体声波谐振器级联而成，具有高工作频率、低插入损耗、高陡降、高功率承受能力等优点，近年来被普遍认为是替代声表面波器件解决无线通信高密集频段双工器的最佳方案。With the rapid development of wireless mobile communication technology, the application fields of bulk acoustic wave devices are becoming more and more extensive. Thin film bulk acoustic resonator (abbreviated as FBAR) has the advantages of high resonance frequency, high quality factor, high power endurance, low power consumption, low price, etc. The bulk acoustic wave filter and duplexer are formed by cascading thin film bulk acoustic resonator It has the advantages of high operating frequency, low insertion loss, high steep drop, high power endurance, etc. In recent years, it is generally considered to be the best solution to replace surface acoustic wave devices to solve the high-density frequency band duplexer of wireless communication.
薄膜压电体声波谐振器的俯视图结构如图1A所示，包括底电极120、压电层130、顶电极140、以及位于底电极下面的声波反射结构110。图1B为沿图1A中的A-A’的截面图，其谐振器主体部分具有三明治结构，其原理为利用压电薄膜材料所具有的逆压电效应，对外界电激励产生一定频率下的谐振。The top view structure of the thin film piezoelectric bulk acoustic resonator is shown in FIG. 1A, and includes a bottom electrode 120, a piezoelectric layer 130, a top electrode 140, and an acoustic wave reflection structure 110 located below the bottom electrode. FIG. 1B is a cross-sectional view along AA′ in FIG. 1A. The resonator body has a sandwich structure. The principle is to use the inverse piezoelectric effect of the piezoelectric thin film material to generate a certain frequency for the external electrical excitation. resonance.
体声波谐振器一般具有两个谐振频率，定义阻抗最小的频率点为串联谐振频率fs，相应阻抗为串联阻抗Rs，阻抗最大的频率点为并联谐振频率fp，相应阻抗为并联阻抗Rp，通过有效机电耦合系数衡量谐振器中压电转换效率。通常，谐振器的串联谐振频率决定了滤波器的中心频率，而谐振器的有效机电耦合系数决定了滤波器可实现的最大带宽，谐振器的串联阻抗和并联阻抗决定了通带插入损耗及回波损耗。一般而言，谐振器的并联阻抗Rp越高，串联阻抗Rs越低，相应滤波器的通带插入损耗越好。因此，如何提高谐振器的性能，特别是提高谐振器的并联阻抗Rp，是滤波器设计中的一个重要而基础的问题。Bulk acoustic wave resonators generally have two resonance frequencies. The frequency point with the smallest impedance is defined as the series resonance frequency fs, the corresponding impedance is the series impedance Rs, and the frequency point with the largest impedance is the parallel resonance frequency fp, and the corresponding impedance is the parallel impedance Rp. The electromechanical coupling coefficient measures the piezoelectric conversion efficiency in the resonator. Generally, the series resonance frequency of the resonator determines the center frequency of the filter, and the effective electromechanical coupling coefficient of the resonator determines the maximum bandwidth that the filter can achieve. The series and parallel impedances of the resonator determine the passband insertion loss and return Wave loss. Generally speaking, the higher the parallel impedance Rp of the resonator and the lower the series impedance Rs, the better the passband insertion loss of the corresponding filter. Therefore, how to improve the performance of the resonator, especially the parallel impedance Rp of the resonator, is an important and fundamental issue in filter design.
理想情况下(谐振区域无限大)，薄膜体声波谐振器仅激发沿纵向扩张的主振动模式，如图1B中的箭头所示。但实际情况中，由于体声波谐振器存在横向边界，因此，会在谐振器内产生横向传播的寄生模式，称为兰姆波，主振动模式的能量会有一部分耦合到兰姆波中。而这种兰姆波会有部分从谐振器两侧泄露进基底中，从而造成 谐振器能量损失，在谐振器的电学性能上表现为并联阻抗(并联阻抗Rp)或并联谐振频率的品质因数(Qp)减小。Ideally (the resonance area is infinitely large), the thin film bulk acoustic resonator only excites the main vibration mode that expands in the longitudinal direction, as shown by the arrows in FIG. 1B. However, in reality, because of the lateral boundary of the bulk acoustic wave resonator, a parasitic mode of lateral propagation will be generated in the resonator, called Lamb wave, and part of the energy of the main vibration mode will be coupled into the Lamb wave. This kind of Lamb wave will partially leak into the substrate from both sides of the resonator, resulting in resonator energy loss. The electrical performance of the resonator is represented by the parallel impedance (parallel impedance Rp) or the quality factor of the parallel resonance frequency ( Qp) decreases.
发明内容Summary of the invention
本发明提出了一种通过设置离散结构提高体声波谐振器的并联阻抗的技术方案。The invention proposes a technical solution for improving the parallel impedance of a bulk acoustic wave resonator by setting a discrete structure.
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，设置在基底上侧；顶电极；和压电层，设置在底电极上侧以及底电极与顶电极之间，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；所述谐振器还包括至少一个离散结构，所述离散结构位于有效区域内侧，且沿有效区域边缘呈条状延伸设置，每个离散结构包括多个离散单元。According to an aspect of an embodiment of the present invention, a bulk acoustic wave resonator is proposed, including: a substrate; an acoustic mirror; a bottom electrode provided on the upper side of the substrate; a top electrode; and a piezoelectric layer provided on the upper side of the bottom electrode and Between the bottom electrode and the top electrode, where: 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 resonator further includes at least one discrete structure, the The discrete structures are located inside the effective area and are arranged in strips along the edges of the effective area. Each discrete structure includes multiple discrete units.
可选的，所述离散结构为环形离散结构。进一步的，所述离散结构与所述有效区域边缘的横向距离保持不变。Optionally, the discrete structure is an annular discrete structure. Further, the lateral distance between the discrete structure and the edge of the effective area remains unchanged.
可选的，所述至少一个离散结构包括一个离散结构。进一步的，所述离散结构设置在顶电极上侧。Optionally, the at least one discrete structure includes a discrete structure. Further, the discrete structure is provided on the upper side of the top electrode.
可选的，所述离散单元为凸起。Optionally, the discrete unit is a protrusion.
可选的，所述离散单元为凹陷。Optionally, the discrete unit is a depression.
可选的，两个相邻离散单元之间的节距为1μm-10μm，或者为所述谐振器并联谐振频率处S1模式兰姆波波长的整数倍。Optionally, the pitch between two adjacent discrete units is 1 μm-10 μm, or an integer multiple of the S1 mode Lamb wave wavelength at the parallel resonance frequency of the resonator.
在进一步的实施例中，单个离散单元的径向尺寸和/或横向尺寸为0.5μm-6μm，或者为所述谐振器并联谐振频率处S1模式兰姆波波长的四分之一或其奇数倍。可选的，所述离散结构距离所述有效区域边缘的距离为0。In a further embodiment, the radial and/or lateral dimensions of a single discrete unit are 0.5 μm-6 μm, or one quarter of the wavelength of the S1 mode Lamb wave or its odd multiple at the parallel resonance frequency of the resonator . Optionally, the distance of the discrete structure from the edge of the effective area is 0.
可选的，所述至少一个离散结构包括至少两个离散结构，所述至少两个离散结构在径向方向上间隔开。Optionally, the at least one discrete structure includes at least two discrete structures, and the at least two discrete structures are spaced apart in the radial direction.
可选的，所述至少两个离散结构包括由凸起组成的凸起离散结构和/或由凹陷组成的凹陷离散结构。Optionally, the at least two discrete structures include convex discrete structures composed of protrusions and/or concave discrete structures composed of depressions.
可选的，径向上相邻的两个离散结构在径向方向上的节距为1μm-10μm，或者为体声波谐振器并联谐振频率处S1模式兰姆波波长的整数倍。Optionally, the pitch of two discrete structures adjacent in the radial direction in the radial direction is 1 μm-10 μm, or an integer multiple of the S1 mode Lamb wave wavelength at the parallel resonance frequency of the bulk acoustic wave resonator.
进一步可选的，每个离散结构的相邻离散单元在横向方向上的节距为1μm-10μm，或者为体声波谐振器并联谐振频率处S1模式兰姆波波长的整数倍。Further optionally, the adjacent discrete units of each discrete structure have a pitch in the lateral direction of 1 μm-10 μm, or an integer multiple of the S1 mode Lamb wave wavelength at the parallel resonance frequency of the bulk acoustic wave resonator.
在一个可选的实施例中，单个离散单元的径向尺寸和/或横向尺寸为0.5μm-6μm， 或者为体声波谐振器并联谐振频率处S1模式兰姆波波长的四分之一或其奇数倍。In an alternative embodiment, the radial dimension and/or lateral dimension of a single discrete unit is 0.5 μm-6 μm, or one quarter of the wavelength of the S1 mode Lamb wave at the parallel resonance frequency of the bulk acoustic wave resonator, or Odd times.
更进一步的，在横向方向上，径向上相邻的两个离散结构中，一个离散结构的一个离散单元与另一个离散结构中与其邻近的一个离散单元之间的横向距离为0-5μm，或者为体声波谐振器并联谐振频率处S1模式兰姆波波长的四分之一或其整数倍。Furthermore, in the lateral direction, in the two discrete structures adjacent in the radial direction, the lateral distance between a discrete unit of one discrete structure and a discrete unit adjacent to it in the other discrete structure is 0-5 μm, or It is a quarter of the wavelength of the S1 mode Lamb wave or its integer multiple at the parallel resonance frequency of the bulk acoustic wave resonator.
可选的，处于外侧的离散结构距离所述有效区域边缘的径向距离为0。Optionally, the radial distance of the outer discrete structure from the edge of the effective area is 0.
可选的，所述离散结构所占谐振器有效区域的面积不超过谐振器的有效区域总面积的20％，可选的，不超过10％。Optionally, the area of the effective area of the resonator occupied by the discrete structure does not exceed 20% of the total area of the effective area of the resonator, and optionally, does not exceed 10%.
可选的，所述离散结构设置于所述压电层、顶电极或者底电极；或者所述谐振器还设置有覆盖顶电极的钝化层，所述离散结构设置于所述钝化层的下侧。Optionally, the discrete structure is provided on the piezoelectric layer, the top electrode, or the bottom electrode; or the resonator is further provided with a passivation layer covering the top electrode, and the discrete structure is provided on the passivation layer Underside.
根据本发明的实施例的另一方面，提出了一种滤波器，包括上述的体声波谐振器。According to another aspect of the embodiments of the present invention, a filter is proposed, including the bulk acoustic wave resonator described above.
根据本发明的实施例的再一方面，提出了一种电子设备，包括上述的滤波器或者上述的谐振器。According to still another aspect of the embodiments of the present invention, an electronic device is proposed, including the above-mentioned filter or the above-mentioned resonator.
本发明还涉及一种提高体声波谐振器的并联阻抗的方法，包括步骤：围绕所述谐振器的有效区域在谐振器的顶电极上侧形成至少一个环形离散结构。The invention also relates to a method for increasing the parallel impedance of a bulk acoustic wave resonator, comprising the steps of forming at least one annular discrete structure on the upper side of the top electrode of the resonator around the effective area of the resonator.
附图说明BRIEF DESCRIPTION
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：The following description and drawings can better help to understand these and other features and advantages in the various embodiments disclosed in the present invention. The same reference numerals in the figures always denote the same parts, among which:
图1A为现有技术中的体声波谐振器的示意性俯视图；FIG. 1A is a schematic top view of a bulk acoustic wave resonator in the prior art;
图1B为沿图1A中的A-A’线截得截面图；Fig. 1B is a cross-sectional view taken along line A-A' in Fig. 1A;
图2A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，其中，仅设置了一个环形离散结构；2A is a schematic top view of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention, in which only one annular discrete structure is provided;
图2B为根据本发明的一个示例性实施例的图2A中的体声波谐振器沿B-B’向的截面图；2B is a cross-sectional view of the bulk acoustic wave resonator in FIG. 2A along the B-B' direction according to an exemplary embodiment of the present invention;
图2C为根据本发明的一个示例性实施例的图2A中的体声波谐振器沿B-B’向的截面图；2C is a cross-sectional view of the bulk acoustic wave resonator in FIG. 2A along the B-B' direction according to an exemplary embodiment of the present invention;
图2D为图2A中的离散结构的尺寸示意图；2D is a schematic diagram of the size of the discrete structure in FIG. 2A;
图3A为根据本发明的另一个示例性实施例的体声波谐振器的示意性俯视图，其中设置了两个环形离散结构；3A is a schematic top view of a bulk acoustic wave resonator according to another exemplary embodiment of the present invention, in which two annular discrete structures are provided;
图3B为根据本发明的一个示例性实施例的图3A中的体声波谐振器沿C-C’向的截面图；3B is a cross-sectional view of the bulk acoustic wave resonator in FIG. 3A along the C-C' direction according to an exemplary embodiment of the present invention;
图3C为根据本发明的一个示例性实施例的图3A中的体声波谐振器沿C-C’向的截面图；3C is a cross-sectional view of the bulk acoustic wave resonator in FIG. 3A along the C-C' direction according to an exemplary embodiment of the present invention;
图3D为根据本发明的一个示例性实施例的图3A中的体声波谐振器沿C-C’向的截面图；3D is a cross-sectional view of the bulk acoustic wave resonator in FIG. 3A along the C-C' direction according to an exemplary embodiment of the present invention;
图3E为根据本发明的一个示例性实施例的图3A中的体声波谐振器沿C-C’向的截面图；3E is a cross-sectional view of the bulk acoustic wave resonator in FIG. 3A along the C-C' direction according to an exemplary embodiment of the present invention;
图3F为图3A中的离散结构的尺寸示意图；3F is a schematic diagram of the size of the discrete structure in FIG. 3A;
图4A为根据本发明的另一个示例性实施例的体声波谐振器的示意性俯视图，其中设置了三个环形离散结构；4A is a schematic top view of a bulk acoustic wave resonator according to another exemplary embodiment of the present invention, in which three annular discrete structures are provided;
图4B为根据本发明的一个示例性实施例的图4A中的体声波谐振器沿D-D’向的截面图；4B is a cross-sectional view of the bulk acoustic wave resonator in FIG. 4A along the D-D' direction according to an exemplary embodiment of the present invention;
图4C为根据本发明的一个示例性实施例的图4A中的体声波谐振器沿D-D’向的截面图；4C is a cross-sectional view along the D-D' direction of the bulk acoustic wave resonator in FIG. 4A according to an exemplary embodiment of the present invention;
图4D为根据本发明的一个示例性实施例的图4A中的体声波谐振器沿D-D’向的截面图；4D is a cross-sectional view of the bulk acoustic wave resonator in FIG. 4A along the D-D' direction according to an exemplary embodiment of the present invention;
图4E为根据本发明的一个示例性实施例的图4A中的体声波谐振器沿D-D’向的截面图；4E is a cross-sectional view of the bulk acoustic wave resonator in FIG. 4A along the D-D' direction according to an exemplary embodiment of the present invention;
图4F为根据本发明的一个示例性实施例的图4A中的体声波谐振器沿D-D’向的截面图；4F is a cross-sectional view of the bulk acoustic wave resonator in FIG. 4A along the D-D' direction according to an exemplary embodiment of the present invention;
图5为根据本发明的一个示例性实施例的多圈离散结构的尺寸示意图；5 is a schematic diagram of dimensions of a multi-turn discrete structure according to an exemplary embodiment of the present invention;
图6A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俯视图，其中，离散结构为单圈，且离散单元具有方形截面；6A is a schematic top view of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention, wherein the discrete structure is a single turn, and the discrete unit has a square cross section;
图6B为根据本发明的一个示例性实施例的图6A中的体声波谐振器沿E-E’向的截面图；6B is a cross-sectional view of the bulk acoustic wave resonator in FIG. 6A along the E-E' direction according to an exemplary embodiment of the present invention;
图6C为根据本发明的一个示例性实施例的图6A中的体声波谐振器沿E-E’向的截面图；6C is a cross-sectional view of the bulk acoustic wave resonator in FIG. 6A along the E-E' direction according to an exemplary embodiment of the present invention;
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俯视图，其中，离散结构为双圈，且离散单元具有方形截面；7 is a schematic top view of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention, wherein the discrete structure is a double loop, and the discrete unit has a square cross section;
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俯视图，其中，离散结构为三圈，且离散单元具有方形截面；8 is a schematic top view of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention, wherein the discrete structure is three turns, and the discrete unit has a square cross section;
图9为体声波谐振器并联谐振频率处S1模式的色散曲线。Fig. 9 is the dispersion curve of the S1 mode at the parallel resonance frequency of the bulk acoustic wave resonator.
具体实施方式detailed description
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。The technical solutions of the present invention will be further specifically described below through the embodiments and the accompanying drawings. In the description, the same or similar reference numerals indicate the same or similar components. The following description of the embodiments of the present invention with reference to the drawings is intended to explain the general inventive concept of the present invention, and should not be construed as a limitation of the present invention.
下面参照附图描述根据本发明的实施例的体声波谐振器。The following describes a bulk acoustic wave resonator according to an embodiment of the present invention with reference to the drawings.
图2A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；图2B为根据本发明的一个示例性实施例的图2A中的体声波谐振器沿B-B’向的截面图。2A is a schematic top view of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention; FIG. 2B is a cross section of the bulk acoustic wave resonator in FIG. 2A along the BB′ direction according to an exemplary embodiment of the present invention Figure.
图2A所示的实施例中，为体声波谐振器的俯视图。该谐振器包括底电极120、压电层130、顶电极140、沿谐振器有效区域边缘设置的单圈离散环形结构150，单个离散结构设置为圆形。The embodiment shown in FIG. 2A is a top view of a bulk acoustic wave resonator. The resonator includes a bottom electrode 120, a piezoelectric layer 130, a top electrode 140, and a single-turn discrete ring structure 150 disposed along the edge of the effective area of the resonator. The single discrete structure is arranged in a circular shape.
图2B所示的实施例中，为体声波谐振器沿着图2A俯视图B-B’所取的截面图。谐振器在厚度方向上依次包括基底100；声学镜110，此声学镜位于基底的上表面或嵌于基底的内部，在图2B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层也同样适用；底电极120、压电层130、顶电极140、以及设置在顶电极边缘内侧的单圈离散环形凸起结构150。In the embodiment shown in FIG. 2B, a cross-sectional view of the bulk acoustic wave resonator taken along the top view B-B' of FIG. 2A. The resonator includes a substrate 100 in the thickness direction; an acoustic mirror 110, which is located on the upper surface of the substrate or embedded inside the substrate. In FIG. 2B, the acoustic mirror is composed of a cavity embedded in the substrate, but any other Acoustic mirror structures such as a Bragg reflector layer are also suitable; the bottom electrode 120, the piezoelectric layer 130, the top electrode 140, and the single-circle discrete annular convex structure 150 disposed inside the edge of the top electrode.
需要指出的是，在本发明中“顶电极边缘内侧”包括了离散结构与顶电极边缘间隔开的情形，也包括了离散结构直接设置在边缘处或者与边缘的距离为零的情形。It should be noted that in the present invention, "inside of the top electrode edge" includes the case where the discrete structure is spaced apart from the edge of the top electrode, and also includes the case where the discrete structure is directly provided at the edge or the distance from the edge is zero.
在本发明中，组成离散结构的为离散单元，例如单个的凹陷或者凸起。In the present invention, discrete units are composed of discrete units, such as individual depressions or protrusions.
在谐振器的有效区域内具有第一声阻抗，而在单圈离散环形结构150中具有第二声阻抗，由于第一声阻抗与第二声阻抗不匹配，从而使得横向传播的声波在电极的边缘处被反射回来，减小了谐振器内声波能量的损失，因而提高了谐振器的并联阻抗Rp 值及相应Q值。It has a first acoustic impedance in the effective area of the resonator, and a second acoustic impedance in the single-circle discrete annular structure 150. Since the first acoustic impedance does not match the second acoustic impedance, the laterally propagating acoustic wave at the electrode It is reflected back at the edge, reducing the loss of acoustic energy in the resonator, thus increasing the parallel resistance Rp value and corresponding Q value of the resonator.
单圈离散环形结构150也可做成凹陷结构，其沿着图2A俯视图B-B’所取的截面图如图2C所示。The single-turn discrete annular structure 150 can also be made into a concave structure, and its cross-sectional view taken along the top view B-B' of FIG. 2A is shown in FIG. 2C.
单圈离散环形结构的各尺寸如图2D所示，L1为离散单元的横向尺寸，S1为相邻离散单元的间隔或者空间，W1为离散单元的纵向尺寸，P1为相邻离散单元的节距，D0为单圈离散环形结构距离谐振器边缘的距离。在可选的实施例中：两个相邻离散单元之间的节距P1的尺寸为1.5μm-10μm，例如1.5μm、8μm和10μm等，或者谐振器并联谐振频率处S1模式兰姆波波长λ的整数倍，例如1倍；离散单元的纵向尺寸W1为相应兰姆波波长的四分之一或其奇数倍，图中S1为相邻离散凸起或者凹陷之间(即相邻离散单元之间)的节距，作为可选的示例，为相应兰姆波波长的四分之三；所述离散结构距离所述有效区域边缘的距离D0可选为0；离散单元的横向尺寸和纵向尺寸相等，即L1等于W1；在可选的实施例中，单个离散单元的径向尺寸和/或横向尺寸为0.5μm-6μm，或者为并联谐振频率处S1模式兰姆波波长的四分之一或其奇数倍。以上实施例仅仅为具体的示例性示例，也可以在上述尺寸数据之间进行组合，均在本发明的保护范围之内。The dimensions of the single-circle discrete ring structure are shown in FIG. 2D, L1 is the horizontal dimension of the discrete unit, S1 is the interval or space of the adjacent discrete unit, W1 is the longitudinal dimension of the discrete unit, and P1 is the pitch of the adjacent discrete unit , D0 is the distance between the single-circle discrete ring structure and the resonator edge. In an alternative embodiment: the size of the pitch P1 between two adjacent discrete units is 1.5 μm-10 μm, such as 1.5 μm, 8 μm, and 10 μm, or the S1 mode Lamb wave wavelength at the parallel resonance frequency of the resonator An integer multiple of λ, for example, 1 times; the longitudinal dimension W1 of the discrete unit is a quarter of the corresponding Lamb wave wavelength or an odd multiple thereof, and S1 in the figure is between adjacent discrete protrusions or depressions (ie, adjacent discrete units Between), as an optional example, is three-quarters of the wavelength of the corresponding Lamb wave; the distance D0 of the discrete structure from the edge of the effective area can be selected as 0; the lateral dimension and longitudinal direction of the discrete unit The dimensions are equal, that is, L1 is equal to W1; in an alternative embodiment, the radial and/or lateral dimensions of a single discrete unit are 0.5 μm-6 μm, or 1/4 of the S1 mode Lamb wave wavelength at the parallel resonance frequency One or its odd multiple. The above embodiment is only a specific exemplary example, and it may also be combined between the above-mentioned size data, which are all within the protection scope of the present invention.
下面简单说明谐振器并联谐振频率处S1模式兰姆波波长λ。如图9所示，在体声波谐振器工作时，三明治结构中会产生大量的振动，若将这些振动按照其频率(f)和波数(k)的关系绘制成色散曲线，则可获得多种模式的曲线，其中1种模式的曲线称为S1模式(其余模式的曲线未在图9中示出)，其具有图9示形状的色散曲线，其中横坐标为波数，纵坐标为振动频率。振动频率为并联谐振频率f p时，对应的波数为k p，而S1模式的波长λ定义为下式：
Figure PCTCN2019121095-appb-000001
The Lamb wave wavelength λ of the S1 mode at the parallel resonance frequency of the resonator is briefly explained below. As shown in Fig. 9, when the bulk acoustic wave resonator works, a lot of vibrations will be generated in the sandwich structure. If these vibrations are plotted as dispersion curves according to the relationship between their frequency (f) and wave number (k), a variety of Curves of modes, one of which is called S1 mode (the curves of the remaining modes are not shown in FIG. 9), which has a dispersion curve of the shape shown in FIG. 9, where the abscissa is the wave number and the ordinate is the vibration frequency. When the vibration frequency is the parallel resonance frequency f p , the corresponding wave number is k p , and the wavelength λ of the S1 mode is defined by the following formula:
Figure PCTCN2019121095-appb-000001
需要指出的是，对于单圈环形离散结构的尺寸的描述，也可以适用于两圈或者多圈环形离散结构中的单圈结构。It should be pointed out that the description of the size of the single-turn annular discrete structure can also be applied to the single-turn structure of the two-turn or multi-turn annular discrete structure.
图3A所示的实施例中，为体声波谐振器的俯视图。该谐振器的顶电极140上设置有两圈离散环形结构：第一圈离散环形结构160和第二圈离散环形结构162。The embodiment shown in FIG. 3A is a top view of a bulk acoustic wave resonator. The top electrode 140 of the resonator is provided with two rings of discrete ring structures: a first ring of discrete ring structures 160 and a second ring of discrete ring structures 162.
图3B所示的实施例中，为体声波谐振器沿着图3A俯视图C-C’所取的截面图。谐振器在厚度方向上依次包括基底100；声学镜110，此声学镜位于基底的上表面或嵌于基底的内部，在图3B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层也同样适用；底电极120、压电层130、顶电极140、以及设 置在顶电极边缘内侧的第一圈离散环凸起结构160和第二圈离散环形凸起结构162。In the embodiment shown in FIG. 3B, it is a cross-sectional view of the bulk acoustic wave resonator taken along the top view C-C' of FIG. 3A. The resonator includes a substrate 100 in the thickness direction; an acoustic mirror 110, which is located on the upper surface of the substrate or embedded inside the substrate. In FIG. 3B, the acoustic mirror is composed of a cavity embedded in the substrate, but any other Acoustic mirror structures such as Bragg reflectors are also suitable; bottom electrode 120, piezoelectric layer 130, top electrode 140, and first ring discrete ring raised structure 160 and second ring discrete ring raised structure disposed inside the top electrode edge 162.
在谐振器的有效区域内具有第一声阻抗，而在环形凸起结构中具有第二声阻抗，由于第一声阻抗与第二声阻抗不匹配，从而使得横向传播的声波在电极的边缘处被反射回来，减小了谐振器内声波能量的损失，因而提高了谐振器的并联阻抗Rp值及Q值。It has a first acoustic impedance in the effective area of the resonator, and a second acoustic impedance in the ring-shaped convex structure. Because the first acoustic impedance does not match the second acoustic impedance, the laterally propagating acoustic wave is at the edge of the electrode Being reflected back reduces the loss of acoustic energy in the resonator, thus increasing the parallel resistance Rp and Q of the resonator.
第一圈离散环形结构160和第二圈离散环形结构162也可全部做成凹陷结构，其沿着图3A俯视图C-C’所取的截面图如图3C所示。The first ring of discrete annular structures 160 and the second ring of discrete annular structures 162 can also all be made into concave structures, and the cross-sectional view taken along the top view C-C' of FIG. 3A is shown in FIG. 3C.
第一圈离散环形结构160和第二圈离散环形结构162也可以做成不同的结构，如图3D所示，第一圈离散环形结构160为凸起结构，第二圈离散环形结构162为凹陷结构；或者如图3E所示，第一圈离散环形结构160为凹陷结构，第二圈离散环形结构162为凸起结构。The first ring discrete ring structure 160 and the second ring discrete ring structure 162 can also be made into different structures, as shown in FIG. 3D, the first ring discrete ring structure 160 is a convex structure, and the second ring discrete ring structure 162 is a depression Or, as shown in FIG. 3E, the first ring of discrete annular structures 160 is a concave structure, and the second ring of discrete annular structures 162 is a convex structure.
双圈离散环形结构的各尺寸如图3F所示，L2为第二圈离散环形结构的离散单元的横向尺寸，S2为第二圈离散环形结构相邻离散单元的间隔或者空间，W2为第二圈离散环形结构的离散单元的纵向尺寸，P2为第二圈离散环形结构的相邻离散单元的节距。d1为第一圈离散环形结构的离散单元和第二圈离散环形结构的邻近离散单元的水平节距，D1为第一圈离散环形结构和第二圈离散环形结构的间隔。在一个可选的实施例中：P2与P1相等，且等于谐振器并联谐振频率处S1模式兰姆波波长，W2与W1为相应兰姆波波长的四分之一，S2和S1为相应兰姆波波长的四分之三，D0为0，D1为相应兰姆波波长的四分之三，d1为0或者相应兰姆波波长的四分之一或二分之一。可选的，L2等于W2。As shown in FIG. 3F, the dimensions of the double-loop discrete ring structure are shown in FIG. 3F. L2 is the lateral dimension of the discrete elements of the second ring discrete ring structure. S2 is the interval or space between the adjacent discrete elements of the second ring discrete ring structure. W2 is the second The longitudinal dimension of the discrete elements of the discrete annular ring structure, P2 is the pitch of the adjacent discrete elements of the discrete annular ring structure of the second circle. d1 is the horizontal pitch of the discrete units of the first ring discrete ring structure and the adjacent discrete units of the second ring discrete ring structure, and D1 is the interval between the first ring discrete ring structure and the second ring discrete ring structure. In an alternative embodiment: P2 is equal to P1 and equal to the S1 mode Lamb wave wavelength at the parallel resonance frequency of the resonator, W2 and W1 are a quarter of the corresponding Lamb wave wavelength, and S2 and S1 are the corresponding blue Three quarters of the Lamb wave wavelength, D0 is 0, D1 is three quarters of the corresponding Lamb wave wavelength, d1 is 0 or one quarter or one half of the corresponding Lamb wave wavelength. Optionally, L2 is equal to W2.
参考图3F，两个离散结构中心线的径向距离W2+D1，可以定义为相邻两个离散结构在径向方向上的节距。该节距可以为1μm-10μm，或者为体声波谐振器并联谐振频率处S1模式兰姆波波长的整数倍。Referring to FIG. 3F, the radial distance W2+D1 of the center lines of two discrete structures can be defined as the pitch of two adjacent discrete structures in the radial direction. The pitch may be 1 μm-10 μm, or an integer multiple of the S1 mode Lamb wave wavelength at the parallel resonance frequency of the bulk acoustic wave resonator.
以上仅为示例性说明，该两个环形结构中的每一离散环形结构可以采用其他尺寸，或者在单圈离散环形结构中描述的具体尺寸及其组合，均在本发明的保护范围之内。图4A所示的实施例中，为体声波谐振器的俯视图。在FBAR顶电极140上设置有三圈离散环形结构：第一圈离散环形结构170、第二圈离散环形结构172和第三圈离散环形结构174。The above are only exemplary descriptions, and each discrete ring structure in the two ring structures may adopt other sizes, or the specific sizes and combinations described in the single ring discrete ring structure are within the protection scope of the present invention. The embodiment shown in FIG. 4A is a top view of a bulk acoustic wave resonator. On the FBAR top electrode 140, three discrete ring structures are provided: a first discrete ring structure 170, a second discrete ring structure 172, and a third discrete ring structure 174.
图4B所示的实施例中，为体声波谐振器沿着图4A俯视图D-D’所取的截面图。 谐振器在厚度方向上依次包括基底100；声学镜110，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层也同样适用；底电极120、压电层130、顶电极140、以及设置在顶电极边缘内侧的第一圈离散环凸起结构170、第二圈离散环形凸起结构172和第三圈离散环形凸起结构174。In the embodiment shown in FIG. 4B, it is a cross-sectional view of the bulk acoustic wave resonator taken along the top view D-D' of FIG. 4A. The resonator includes a substrate 100 in the thickness direction; an acoustic mirror 110, which is located on the upper surface of the substrate or embedded inside the substrate. In FIG. 4B, the acoustic mirror is composed of a cavity embedded in the substrate, but any other Acoustic mirror structures such as the Bragg reflector layer are also suitable; the bottom electrode 120, the piezoelectric layer 130, the top electrode 140, and the first ring of discrete ring convex structures 170 and the second ring of discrete ring convex structures disposed inside the edge of the top electrode 172 and the third ring of discrete annular convex structures 174.
在谐振器的有效区域内具有第一声阻抗，而在环形凸起结构中具有第二声阻抗，由于第一声阻抗与第二声阻抗不匹配，从而使得横向传播的声波在电极的边缘处被反射回来，减小了谐振器内声波能量的损失，因而提高了谐振器的并联阻抗Rp值及Q值。It has a first acoustic impedance in the effective area of the resonator, and a second acoustic impedance in the ring-shaped convex structure. Because the first acoustic impedance does not match the second acoustic impedance, the laterally propagating acoustic wave is at the edge of the electrode Being reflected back reduces the loss of acoustic energy in the resonator, thus increasing the parallel resistance Rp and Q of the resonator.
第一圈离散环形结构170、第二圈离散环形结构172和第三圈离散环形结构174也可全部做成凹陷结构，其沿着图4A俯视图D-D’所取的截面图如图4C所示。The first ring discrete ring structure 170, the second ring discrete ring structure 172 and the third ring discrete ring structure 174 can also all be made into a concave structure, and the cross-sectional view taken along the top view DD' of FIG. 4A is shown in FIG. 4C Show.
第一圈离散环形结构170、第二圈离散环形结构172和第三圈离散环形结构174也可做成不同的凹凸结构，如图4D所示，第一圈离散环形结构170和第二圈离散环形结构172为凸起结构，第三圈离散环形结构174为凹陷结构；或者如图4E所示，第一圈离散环形结构170和第三圈离散环形结构174为凸起结构，第二圈离散环形结构172为凹陷结构；或者如图4F所示，第一圈离散环形结构170为凸起结构，第二圈离散环形结构172和第三圈离散环形结构174为凹陷结构。在本发明中，附图中仅示出了一部分组合形式，还可以有其他不同形式的组合，本发明未一一列出。The first ring discrete ring structure 170, the second ring discrete ring structure 172 and the third ring discrete ring structure 174 can also be made into different concave-convex structures, as shown in FIG. 4D, the first ring discrete ring structure 170 and the second ring discrete The ring structure 172 is a convex structure, and the third ring discrete ring structure 174 is a concave structure; or as shown in FIG. 4E, the first ring discrete ring structure 170 and the third ring discrete ring structure 174 are convex structures, and the second ring discrete The ring structure 172 is a concave structure; or as shown in FIG. 4F, the first ring discrete ring structure 170 is a convex structure, the second ring discrete ring structure 172 and the third ring discrete ring structure 174 are concave structures. In the present invention, only a part of the combination forms are shown in the drawings, and there may be other combinations of different forms, and the invention is not listed one by one.
实施例3列出了顶电极设置有三圈离散环形结构的体声波谐振器，还可以设置四圈或更多圈。Embodiment 3 lists a bulk acoustic wave resonator in which the top electrode is provided with a three-ring discrete ring structure, and four or more turns may also be provided.
多圈离散环形结构的各尺寸如图5所示，Ln为第n圈离散环形结构的横向尺寸，Sn为第n圈离散环形结构的相邻离散单元的间隔或者空间，Wn为第n圈离散环形结构的纵向尺寸，Pn为第n圈离散环形结构的相邻离散单元的节距。dn-1为第n-1圈离散环形结构的一个离散单元和第n圈离散环形结构的一个相邻离散单元的水平节距，Dn-1为第n-1圈离散环形结构和第n圈离散环形结构的(在径向或者纵向上的)间隔。在一个可选的示例中：Pn均相等且等于谐振器并联谐振频率处S1模式兰姆波波长，Wn为相应兰姆波波长的四分之一，Sn为相应兰姆波波长的四分之三，D0为0，Dn-1为相应兰姆波波长的四分之三，dn-1为0或者相应兰姆波波长的四分之一或二分之一。以上仅为示例性说明，该多个离散环形结构可以为其他尺寸。该多个环形结构中的每 一离散环形结构可以采用其他尺寸，或者在单圈离散环形结构中描述的具体尺寸及其组合，均在本发明的保护范围之内。The dimensions of the multi-turn discrete ring structure are shown in Figure 5, Ln is the lateral dimension of the n-th discrete ring structure, Sn is the interval or space of adjacent discrete units of the n-th discrete ring structure, and Wn is the n-th discrete The longitudinal dimension of the ring structure, Pn is the pitch of the adjacent discrete units of the n-th discrete ring structure. dn-1 is the horizontal pitch of a discrete element of the n-1th discrete ring structure and an adjacent discrete element of the nth discrete ring structure, Dn-1 is the discrete ring structure of the n-1th ring and the nth circle Discrete annular structure (in the radial or longitudinal direction) spacing. In an optional example: Pn is equal and equal to the S1 mode Lamb wave wavelength at the parallel resonance frequency of the resonator, Wn is a quarter of the corresponding Lamb wave wavelength, Sn is a quarter of the corresponding Lamb wave wavelength Three, D0 is 0, Dn-1 is three quarters of the corresponding Lamb wave wavelength, and dn-1 is 0 or one quarter or one half of the corresponding Lamb wave wavelength. The above are only exemplary descriptions, and the plurality of discrete ring structures may have other sizes. Each discrete ring structure of the plurality of ring structures may adopt other sizes, or the specific sizes and combinations described in the single-turn discrete ring structure are all within the protection scope of the present invention.
在本发明中，多个离散结构的尺寸可以是如下的形式：In the present invention, the size of the multiple discrete structures may be in the following form:
例如，径向上相邻的两个离散结构在径向方向上的节距为1μm-10μm，或者为体声波谐振器并联谐振频率处S1模式兰姆波波长的整数倍。For example, the pitch of two discrete structures adjacent in the radial direction in the radial direction is 1 μm-10 μm, or an integer multiple of the S1 mode Lamb wave wavelength at the parallel resonance frequency of the bulk acoustic wave resonator.
再如，每个离散结构的相邻离散单元在横向方向上的节距为1μm-10μm，或者为体声波谐振器并联谐振频率处S1模式兰姆波波长的整数倍。As another example, the pitch of the adjacent discrete units of each discrete structure in the lateral direction is 1 μm-10 μm, or an integer multiple of the S1 mode Lamb wave wavelength at the parallel resonance frequency of the bulk acoustic wave resonator.
再如，单个离散单元的径向尺寸和/或横向尺寸为0.5μm-6μm，或者为体声波谐振器并联谐振频率处S1模式兰姆波波长的四分之一或其奇数倍。As another example, the radial dimension and/or lateral dimension of a single discrete unit is 0.5 μm-6 μm, or a quarter of the wavelength of the S1 mode Lamb wave or an odd multiple thereof at the parallel resonance frequency of the bulk acoustic wave resonator.
可选的，在横向方向上，径向上(或者纵向上)相邻的两个离散结构中，一个离散结构的一个离散单元与另一个离散结构中与其邻近的一个离散单元之间的横向节距为0-5μm，或者为体声波谐振器并联谐振频率处S1模式兰姆波波长的四分之一或其整数倍。Optionally, in a lateral direction, among two discrete structures adjacent in the radial direction (or longitudinal direction), a lateral pitch between a discrete unit of a discrete structure and a discrete unit adjacent thereto in another discrete structure 0-5μm, or a quarter of the wavelength of the S1 mode Lamb wave or its integral multiple at the parallel resonance frequency of the bulk acoustic wave resonator.
在可选的实施例中，离散环形结构所占谐振器有效区域的面积不超过谐振器有效区域的总面积的20％，优选的低于10％。In an alternative embodiment, the area of the effective area of the resonator occupied by the discrete ring structure does not exceed 20% of the total area of the effective area of the resonator, preferably less than 10%.
可选的，离散单元的纵向尺寸与横向尺寸相同，即Ln等于Wn。Optionally, the longitudinal dimension of the discrete unit is the same as the lateral dimension, that is, Ln is equal to Wn.
除圆形结构外，也可将薄膜体声波谐振结构顶电极上的离散环形结构做成方形，如图6A所示。210为单圈离散环形结构。In addition to the circular structure, the discrete ring structure on the top electrode of the thin film bulk acoustic resonance structure can also be made square, as shown in FIG. 6A. 210 is a single-turn discrete ring structure.
图6B所示的实施例中，为体声波谐振器沿着图6A俯视图E-E’所取的截面图。谐振器在厚度方向上依次包括基底100；声学镜110，此声学镜位于基底的上表面或嵌于基底的内部，在图6B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层也同样适用；底电极120、压电层130、顶电极140、以及设置在顶电极边缘内侧的单圈离散环形结构210。In the embodiment shown in FIG. 6B, it is a cross-sectional view of the bulk acoustic wave resonator taken along the top view E-E' of FIG. 6A. The resonator includes a substrate 100 in the thickness direction; an acoustic mirror 110, which is located on the upper surface of the substrate or embedded inside the substrate. In FIG. 6B, the acoustic mirror is composed of a cavity embedded in the substrate, but any other Acoustic mirror structures such as a Bragg reflector layer are also suitable; the bottom electrode 120, the piezoelectric layer 130, the top electrode 140, and the single-circle discrete annular structure 210 disposed inside the edge of the top electrode.
在谐振器的有效区域内具有第一声阻抗，而在环形凸起结构中具有第二声阻抗，由于第一声阻抗与第二声阻抗不匹配，从而使得横向传播的声波在电极的边缘处被反射回来，减小了谐振器内声波能量的损失，因而提高了谐振器的并联阻抗Rp值及Q值。It has a first acoustic impedance in the effective area of the resonator, and a second acoustic impedance in the ring-shaped convex structure. Because the first acoustic impedance does not match the second acoustic impedance, the laterally propagating acoustic wave is at the edge of the electrode Being reflected back reduces the loss of acoustic energy in the resonator, thus increasing the parallel resistance Rp and Q of the resonator.
单圈离散环形结构210也可做成凹陷结构，其沿着图6A俯视图E-E’所取的截 面图如图6C所示。The single-circle discrete annular structure 210 can also be made into a concave structure, and its cross-sectional view taken along the top view E-E' of FIG. 6A is shown in FIG. 6C.
同样也可在薄膜体声波谐振结构顶电极上设置两圈、三圈或多圈方形离散环形结构。图7为双圈方形离散环形结构，图8为三圈方形离散环形结构。Similarly, two, three, or multiple rings of square discrete ring structures can be provided on the top electrode of the thin film bulk acoustic resonance structure. Fig. 7 is a double-circle square discrete ring structure, and Fig. 8 is a three-circle square discrete ring structure.
在本发明中，对于凸起或者凹陷，其截面的方形结构的尺寸需满足和圆形截面的凸起或者凹陷相同的尺寸要求。除圆形、方形外，离散环形结构中的离散单元的截面也可为其他的形状。In the present invention, for the protrusions or depressions, the size of the square structure of the cross section needs to meet the same size requirements as the protrusions or depressions of the circular cross section. In addition to the circular and square shapes, the cross-section of the discrete cells in the discrete ring structure can also have other shapes.
在本发明中，离散结构可以是金属或者介质材料，也可以为与压电层或者电极相同的材料。所述介质材料可以为氮化铝、二氧化硅、氮化硅等。金属可以为金(Au)、钨(W)、钼(Mo)、铂(Pt)等。In the present invention, the discrete structure may be a metal or dielectric material, or the same material as the piezoelectric layer or electrode. The dielectric material may be aluminum nitride, silicon dioxide, silicon nitride, or the like. The metal may be gold (Au), tungsten (W), molybdenum (Mo), platinum (Pt), or the like.
基于以上，本发明提出了一种体声波谐振器，包括：Based on the above, the present invention proposes a bulk acoustic wave resonator, including:
基底100； Base 100;
声学镜110； Acoustic mirror 110;
底电极120，设置在基底100上侧；The bottom electrode 120 is provided on the upper side of the substrate 100;
顶电极140；和 Top electrode 140; and
压电层130，设置在底电极上侧以及底电极与顶电极之间，The piezoelectric layer 130 is provided on the upper side of the bottom electrode and between the bottom electrode and the top electrode,
其中：among them:
声学镜110、底电极120、压电层130、顶电极140在基底100的厚度方向重叠的区域为谐振器的有效区域；The area where the acoustic mirror 110, the bottom electrode 120, the piezoelectric layer 130, and the top electrode 140 overlap in the thickness direction of the substrate 100 is the effective area of the resonator;
所述谐振器还包括至少一个离散结构150或160或170，所述离散结构在所述有效区域内侧呈条状延伸设置，每个离散结构包括多个离散单元。这里的离散单元可以认为是例如单个的凸起或者凹陷。The resonator further includes at least one discrete structure 150 or 160 or 170. The discrete structures extend in a strip shape inside the effective area, and each discrete structure includes a plurality of discrete cells. The discrete unit here can be considered as a single protrusion or depression, for example.
以顶电极上设置离散结构为例，通过在顶电极的有效区域内侧增加有规律分布的离散凸起或凹陷结构，此结构可导致有效区域边缘的阻抗不匹配，进而会使得声波在边界处被反射回有效激励区域中，从而有机会转换成主振动模式，减少谐振器中能量的损耗，从而提高并联阻抗Rp。Taking a discrete structure on the top electrode as an example, by adding a regularly distributed discrete convex or concave structure inside the effective area of the top electrode, this structure can cause impedance mismatch at the edge of the effective area, which in turn causes sound waves to be trapped at the boundary Reflect back into the effective excitation area, thus have the opportunity to convert to the main vibration mode, reduce the loss of energy in the resonator, and thus increase the parallel impedance Rp.
在本发明中，在谐振器的有效区域的一边或多边边缘处，在例如顶电极上加工一种离散结构，实践中通过选择合适的离散结构尺寸，能够有效反射泄露到基底中的声波，从而有效提高谐振器并联阻抗Rp值。In the present invention, a discrete structure is processed on, for example, the top electrode at one or more edges of the effective area of the resonator. In practice, by selecting an appropriate discrete structure size, sound waves leaking into the substrate can be effectively reflected, thereby Effectively increase the resonator parallel resistance Rp value.
在本发明的附图中，离散结构为环形离散结构。不过，离散结构也可以为多个离 散结构段，所述多个离散结构段彼此之间间隔开且沿围绕所述有效区域内侧设置。例如，离散结构段可以为设置在图2A中所示的多边形的有效区域的一条边或多条边的一个或多个离散结构段。In the drawings of the present invention, the discrete structure is an annular discrete structure. However, the discrete structure may also be a plurality of discrete structure segments that are spaced apart from each other and are arranged along the inside of the effective area. For example, the discrete structure segment may be one or more discrete structure segments disposed on one side or multiple sides of the effective area of the polygon shown in FIG. 2A.
在本发明中，如附图所示，在可选的实施例中，所述离散结构与所述有效区域的横向距离保持不变。In the present invention, as shown in the drawings, in an alternative embodiment, the lateral distance between the discrete structure and the effective area remains unchanged.
在本发明的一个示例性实施例中，离散结构均形成在顶电极上。但是，本发明不限于此。离散结构可设置于所述压电层的下侧或者上侧；或者离散结构设置于所述顶电极的下侧；或者离散结构设置于所述底电极的上侧或者下侧；或者谐振器还设置有覆盖顶电极的钝化层，所述离散结构设置于所述钝化层下侧，等等。In an exemplary embodiment of the invention, the discrete structures are all formed on the top electrode. However, the present invention is not limited to this. The discrete structure may be provided on the lower or upper side of the piezoelectric layer; or the discrete structure may be provided on the lower side of the top electrode; or the discrete structure may be provided on the upper or lower side of the bottom electrode; or the resonator may also A passivation layer covering the top electrode is provided, the discrete structure is provided under the passivation layer, and so on.
在本发明中，方位中的“上侧”表示在谐振器的厚度方向上远离基底的一侧，而“下侧”表示在谐振器的厚度方向上靠近基底的一侧。In the present invention, the "upper side" in the orientation means the side away from the substrate in the thickness direction of the resonator, and the "lower side" means the side close to the substrate in the thickness direction of the resonator.
基于以上，本发明的实施例也涉及一种滤波器，包括上述的体声波谐振器。Based on the above, the embodiments of the present invention also relate to a filter including the bulk acoustic wave resonator described above.
本发明的实施例也涉及一种电子设备，包括上述的滤波器或者谐振器。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。Embodiments of the present invention also relate to an electronic device, including the above-mentioned filter or resonator. It should be noted that 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.
相应的，本发明还提出了一种提高体声波谐振器的并联阻抗的方法，包括步骤：围绕所述谐振器的有效区域在谐振器的顶电极上侧形成至少一个环形离散结构。Correspondingly, the present invention also proposes a method for increasing the parallel impedance of a bulk acoustic wave resonator, comprising the steps of forming at least one annular discrete structure on the upper side of the top electrode of the resonator around the effective area of the resonator.
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。Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that these embodiments can be changed without departing from the principle and spirit of the present invention. The appended claims and their equivalents are limited.

Claims (25)

  1. 一种体声波谐振器，包括：A bulk acoustic wave resonator includes:
    基底；Base
    声学镜；Acoustic mirror
    底电极，设置在基底上侧；The bottom electrode is arranged on the upper side of the substrate;
    顶电极；和Top electrode; and
    压电层，设置在底电极上侧以及底电极与顶电极之间，The piezoelectric layer is provided on the upper side of the bottom electrode and between the bottom electrode and the top electrode,
    其中：among them:
    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；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;
    所述谐振器还包括至少一个离散结构，所述离散结构位于有效区域内侧，且沿有效区域边缘呈条状延伸设置，每个离散结构包括多个离散单元。The resonator further includes at least one discrete structure. The discrete structure is located inside the effective area and extends in a strip shape along the edge of the effective area. Each discrete structure includes a plurality of discrete units.
  2. 根据权利要求1所述的谐振器，其中：The resonator according to claim 1, wherein:
    所述离散结构为环形离散结构。The discrete structure is an annular discrete structure.
  3. 根据权利要求2所述的谐振器，其中：The resonator according to claim 2, wherein:
    所述离散结构与所述有效区域边缘的横向距离保持不变。The lateral distance between the discrete structure and the edge of the effective area remains unchanged.
  4. 根据权利要求1-3中任一项所述的谐振器，其中：The resonator according to any one of claims 1 to 3, wherein:
    所述至少一个离散结构包括一个离散结构。The at least one discrete structure includes a discrete structure.
  5. 根据权利要求4所述的谐振器，其中：The resonator according to claim 4, wherein:
    所述离散结构设置在顶电极上侧。The discrete structure is provided on the upper side of the top electrode.
  6. 根据权利要求5所述的谐振器，其中：The resonator according to claim 5, wherein:
    所述离散单元为凸起。The discrete unit is a protrusion.
  7. 根据权利要求5所述的谐振器，其中：The resonator according to claim 5, wherein:
    所述离散单元为凹陷。The discrete unit is a depression.
  8. 根据权利要求5-7中任一项所述的谐振器，其中：The resonator according to any one of claims 5-7, wherein:
    两个相邻离散单元之间的节距为1μm-10μm，或者为体声波谐振器并联谐振频率处S1模式兰姆波波长的整数倍。The pitch between two adjacent discrete units is 1μm-10μm, or an integer multiple of the S1 mode Lamb wave wavelength at the parallel resonance frequency of the bulk acoustic wave resonator.
  9. 根据权利要求7或8所述的谐振器，其中：The resonator according to claim 7 or 8, wherein:
    单个离散单元的径向尺寸和/或横向尺寸为0.5μm-6μm，或者为并联谐振频率处 S1模式兰姆波波长的四分之一或其奇数倍。The radial and/or lateral dimensions of a single discrete unit are 0.5 μm to 6 μm, or one quarter of the wavelength of the S1 mode Lamb wave or its odd multiple at the parallel resonance frequency.
  10. 根据权利要求9所述的谐振器，其中：The resonator according to claim 9, wherein:
    所述离散结构距离所述有效区域边缘的距离为0。The distance of the discrete structure from the edge of the effective area is 0.
  11. 根据权利要求1-3中任一项所述的谐振器，其中：The resonator according to any one of claims 1 to 3, wherein:
    所述至少一个离散结构包括至少两个离散结构，所述至少两个离散结构在径向方向上间隔开。The at least one discrete structure includes at least two discrete structures that are spaced apart in the radial direction.
  12. 根据权利要求11所述的谐振器，其中：The resonator according to claim 11, wherein:
    所述至少两个离散结构包括由凸起组成的凸起离散结构和/或由凹陷组成的凹陷离散结构。The at least two discrete structures include convex discrete structures composed of protrusions and/or concave discrete structures composed of depressions.
  13. 根据权利要求11或12所述的谐振器，其中：The resonator according to claim 11 or 12, wherein:
    径向上相邻的两个离散结构在径向方向上的节距为1μm-10μm，或者为体声波谐振器并联谐振频率处S1模式兰姆波波长的整数倍。The pitch of two discrete structures adjacent in the radial direction in the radial direction is 1 μm-10 μm, or an integer multiple of the S1 mode Lamb wave wavelength at the parallel resonance frequency of the bulk acoustic wave resonator.
  14. 根据权利要求13所述的谐振器，其中：The resonator according to claim 13, wherein:
    每个离散结构的相邻离散单元在横向方向上的节距为1μm-10μm，或者为体声波谐振器并联谐振频率处S1模式兰姆波波长的整数倍。The adjacent discrete units of each discrete structure have a pitch in the lateral direction of 1 μm-10 μm, or an integer multiple of the S1 mode Lamb wave wavelength at the parallel resonance frequency of the bulk acoustic wave resonator.
  15. 根据权利要求14所述的谐振器，其中：The resonator according to claim 14, wherein:
    单个离散单元的径向尺寸和/或横向尺寸为0.5μm-6μm，或者为体声波谐振器并联谐振频率处S1模式兰姆波波长的四分之一或其奇数倍。The radial and/or lateral dimensions of a single discrete unit are 0.5 μm-6 μm, or one quarter of the wavelength of the S1 mode Lamb wave or its odd multiple at the parallel resonance frequency of the bulk acoustic wave resonator.
  16. 根据权利要求14或15所述的谐振器，其中：The resonator according to claim 14 or 15, wherein:
    在横向方向上，径向上相邻的两个离散结构中，一个离散结构的一个离散单元与另一个离散结构中与其邻近的一个离散单元之间的横向节距为0-5μm，或者为体声波谐振器并联谐振频率处S1模式兰姆波波长的四分之一或其整数倍。In the lateral direction, in the two discrete structures adjacent in the radial direction, the lateral pitch between a discrete unit of one discrete structure and a discrete unit adjacent to it in the other discrete structure is 0-5 μm, or it is bulk acoustic The quarter-wavelength of the S1 mode Lamb wave or its integer multiple at the parallel resonance frequency of the resonator.
  17. 根据权利要求16所述的谐振器，其中：The resonator according to claim 16, wherein:
    处于外侧的离散结构距离所述有效区域边缘的径向距离为0。The radial distance of the outer discrete structure from the edge of the effective area is 0.
  18. 根据权利要求1-17中任一项所述的谐振器，其中：The resonator according to any one of claims 1-17, wherein:
    所述离散结构所占谐振器的有效区域面积不超过谐振器的有效区域总面积的20％。The area of the effective area of the resonator occupied by the discrete structure does not exceed 20% of the total area of the effective area of the resonator.
  19. 根据权利要求18所述的谐振器，其中：The resonator according to claim 18, wherein:
    所述离散结构所占谐振器的有效区域面积不超过谐振器的有效区域总面积的10％。The discrete structure occupies an effective area of the resonator that does not exceed 10% of the total area of the effective area of the resonator.
  20. 根据权利要求1-3中任一项所述的谐振器，其中：The resonator according to any one of claims 1 to 3, wherein:
    所述离散结构设置于所述压电层、顶电极或者底电极；或者The discrete structure is provided on the piezoelectric layer, the top electrode or the bottom electrode; or
    所述谐振器还设置有覆盖顶电极的钝化层，所述离散结构设置于所述钝化层的下侧。The resonator is further provided with a passivation layer covering the top electrode, and the discrete structure is provided on the lower side of the passivation layer.
  21. 根据权利要求1-3中任一项所述的谐振器，其中：The resonator according to any one of claims 1 to 3, wherein:
    形成所述离散结构的材料包括金属、介质材料或者与压电层或者电极相同的材料。The material forming the discrete structure includes metal, dielectric material, or the same material as the piezoelectric layer or electrode.
  22. 根据权利要求1-3中任一项所述的谐振器，其中：The resonator according to any one of claims 1 to 3, wherein:
    所述离散单元的横截面形状为圆形或者方形。The cross-sectional shape of the discrete unit is circular or square.
  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。A filter comprising a bulk acoustic wave resonator according to any one of claims 1-22.
  24. 一种电子设备，包括根据权利要求23所述的滤波器或者根据权利要求1-22中任一项所述的谐振器。An electronic device comprising the filter according to claim 23 or the resonator according to any one of claims 1-22.
  25. 一种提高体声波谐振器的并联阻抗的方法，包括步骤：A method for increasing the parallel impedance of a bulk acoustic wave resonator includes the steps of:
    围绕所述谐振器的有效区域在谐振器的顶电极上侧形成至少一个环形离散结构。At least one annular discrete structure is formed on the upper side of the top electrode of the resonator around the effective area of the resonator.
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