WO2020125354A1 - Résonateur à ondes acoustiques de volume ayant une surface distincte, filtre et dispositif électronique - Google Patents

Résonateur à ondes acoustiques de volume ayant une surface distincte, filtre et dispositif électronique 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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English (en)
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/fr

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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 piezoelectric 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.

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  • Acoustics & Sound (AREA)
  • Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)

Abstract

La présente invention concerne un résonateur à ondes acoustiques de volume, qui comprend : un substrat; un miroir acoustique; une électrode inférieure, qui est disposée sur le côté supérieur du substrat; une électrode supérieure; et une couche piézoélectrique, qui est disposée au-dessus de l'électrode inférieure et entre l'électrode inférieure et l'électrode supérieure, la zone où le miroir acoustique, l'électrode inférieure, la couche piézoélectrique et l'électrode supérieure se chevauchent dans la direction de l'épaisseur du substrat étant une zone efficace du résonateur; le résonateur comprend en outre au moins une structure distincte, la structure distincte est située à l'intérieur de la zone efficace, et s'étend dans une forme de bande le long du bord de la zone efficace, et chaque structure distincte comprend une pluralité d'unités distinctes. La présente invention concerne en outre un filtre avec le résonateur, et un dispositif électronique avec le filtre ou résonateur.
PCT/CN2019/121095 2018-12-19 2019-11-27 Résonateur à ondes acoustiques de volume ayant une surface distincte, filtre et dispositif électronique WO2020125354A1 (fr)

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CN201811558423.XA CN111342800A (zh) 2018-12-19 2018-12-19 带离散结构的体声波谐振器、滤波器和电子设备
CN201811558423.X 2018-12-19

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CN111934641B (zh) * 2020-07-08 2021-06-01 诺思(天津)微系统有限责任公司 体声波谐振器及其频率调整方法、滤波器、电子设备
CN113364422A (zh) * 2021-06-18 2021-09-07 深圳市封神微电子有限公司 具有环形电极的薄膜体声波谐振器

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