WO2022143286A1 - 单晶体声波谐振器、滤波器及电子设备 - Google Patents

单晶体声波谐振器、滤波器及电子设备 Download PDF

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WO2022143286A1
WO2022143286A1 PCT/CN2021/139954 CN2021139954W WO2022143286A1 WO 2022143286 A1 WO2022143286 A1 WO 2022143286A1 CN 2021139954 W CN2021139954 W CN 2021139954W WO 2022143286 A1 WO2022143286 A1 WO 2022143286A1
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electrode
layer
resonator
gap
piezoelectric layer
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PCT/CN2021/139954
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English (en)
French (fr)
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张孟伦
庞慰
牛鹏飞
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诺思(天津)微系统有限责任公司
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/05—Holders; Supports
    • 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

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  • Embodiments of the present invention relate to the field of semiconductors, and in particular, to a single crystal acoustic wave resonator, a filter having the resonator, and an electronic device.
  • FBAR Film Bulk Acoustic Resonator
  • BAW Bulk Acoustic Resonator
  • the main structure of the thin film bulk acoustic wave resonator is a "sandwich" structure composed of a bottom electrode-piezoelectric film or a piezoelectric layer-top electrode, that is, a piezoelectric material is sandwiched between two metal electrode layers.
  • the FBAR uses the inverse piezoelectric effect to convert the input electrical signal into mechanical resonance, and then uses the piezoelectric effect to convert the mechanical resonance into an electrical signal output.
  • the piezoelectric layer is generally deposited on the structured bottom electrode by a semiconductor thin-film deposition process (such as sputtering process).
  • the obtained piezoelectric film has a polymorphic crystal structure, and the crystal structure at the bend is very different from the straight one, which affects the electromechanical coupling and the uniformity of the heat transfer performance of the piezoelectric film.
  • a good piezoelectric film puts forward very strict requirements on the topography and structure of the bottom electrode.
  • the edge of the electrode has a slope as gentle as possible, and the angle is usually between 10 and 20°, which causes great difficulties in processing; It is also almost impossible to fabricate interference structures (such as wings, bridges, etc.) on the bottom electrode to improve the performance of the resonator. These factors limit the performance of traditional bulk acoustic wave resonators based on growing piezoelectric thin films.
  • the rapid development of communication technology requires that the operating frequency of the filter is continuously increased.
  • the high operating frequency means that the film thickness, especially the film thickness of the electrode, needs to be further reduced; however, the main negative effect of the reduction in the thickness of the electrode film is electrical loss.
  • the increase leads to a decrease in the Q value of the resonator, especially at the series resonance point and its frequency; correspondingly, the performance of the high operating frequency BAW filter also deteriorates significantly with the decrease in the Q value of the BAW resonator .
  • the present invention is proposed to alleviate or solve at least one aspect of the above-mentioned problems in the prior art.
  • a bulk acoustic wave resonator comprising:
  • the single crystal piezoelectric layer is arranged between the bottom electrode and the top electrode,
  • a support structure is arranged between the lower surface of the piezoelectric layer and the upper surface of the substrate, and the piezoelectric layer and the substrate are generally arranged in parallel;
  • the bottom electrode and/or the top electrode is a gap electrode, and the gap electrode has at least one gap layer, and in the thickness direction of the gap electrode, there is a distance between the gap layer and the top surface and the bottom surface of the gap electrode;
  • the support structure includes a recess in which the bottom electrode is disposed.
  • Embodiments of the present invention also relate to a filter comprising the above-mentioned bulk acoustic wave resonator.
  • Embodiments of the present invention also relate to an electronic device comprising the above-mentioned filter or the above-mentioned resonator.
  • FIG. 1A-1C are a schematic top view of a bulk acoustic wave resonator according to the first exemplary embodiment of the present invention, a schematic cross-sectional view along line AA' in FIG. 1A , and a schematic view along line BB' in FIG. 1A , respectively.
  • FIG. 2A-2C are a schematic top view of a bulk acoustic wave resonator according to a second exemplary embodiment of the present invention, a schematic cross-sectional view along line AA' in FIG. 2A, and a schematic cross-section along line BB' in FIG. 2A picture;
  • 3A-3C are a schematic top view of a bulk acoustic wave resonator according to a third exemplary embodiment of the present invention, a schematic cross-sectional view along line AA' in FIG. 3A, and a schematic cross-section along line BB' in FIG. 3A picture;
  • FIG. 4A-4C are a schematic top view of a bulk acoustic wave resonator according to a fourth exemplary embodiment of the present invention, a schematic cross-sectional view along line AA' in FIG. 4A, and a schematic cross-section along line BB' in FIG. 4A picture;
  • 5A-5C are a schematic top view of a bulk acoustic wave resonator according to a fifth exemplary embodiment of the present invention, a schematic cross-sectional view along line AA' in FIG. 5A, and a schematic cross-section along line BB' in FIG. 5A picture;
  • 6A-6C are a schematic top view of a bulk acoustic wave resonator according to a sixth exemplary embodiment of the present invention, a schematic cross-sectional view along line AA' in FIG. 6A, and a schematic cross-section along line BB' in FIG. 6A picture;
  • FIG. 7A-7C are a schematic top view, a schematic cross-sectional view along line AA' in FIG. 7A, and a schematic cross-sectional view along line BB' in FIG. 7A of a bulk acoustic wave resonator according to a seventh exemplary embodiment of the present invention picture;
  • FIG. 8A-8C are a schematic top view of a bulk acoustic wave resonator according to an eighth exemplary embodiment of the present invention, a schematic cross-sectional view along line AA' in FIG. 8A, and a schematic cross-section along line BB' in FIG. 8A picture;
  • FIGS. 9A-9C are a schematic top view of a bulk acoustic wave resonator according to a ninth exemplary embodiment of the present invention, a schematic cross-sectional view along line AA' in FIG. 9A , and a schematic cross-section along line BB' in FIG. 9A . picture;
  • FIG. 10A-10C are a schematic top view, a schematic cross-sectional view along line AA' in FIG. 10A , and a schematic cross-sectional view along line BB' in FIG. 10A of a bulk acoustic wave resonator according to a tenth exemplary embodiment of the present invention Figure, which shows the insulating layer.
  • the invention proposes a bulk acoustic wave resonator structure made by POI (Piezoelectrics on Insulator, single crystal piezoelectric layer on insulator) substrate.
  • the POI substrate includes an auxiliary substrate, a single crystal piezoelectric layer, and an insulating layer disposed between the single crystal piezoelectric layer and the auxiliary substrate.
  • the bottom electrode and/or the top electrode of the bulk acoustic wave resonator according to the present invention is a gap electrode or a hollow electrode, the gap electrode has a gap layer disposed between the first electrode layer and the second electrode layer, and the first electrode layer is connected to the second electrode layer.
  • the two electrode layers are electrically connected to each other, which improves the conductivity of the entire gap electrode. By arranging gap electrodes, the electrical and acoustic properties of the resonator can be improved.
  • the electrode structure on both sides of the piezoelectric layer does not affect the intrinsic properties of the piezoelectric layer, which is conducive to the diversified structure design of electrodes, It is beneficial to improve the comprehensive performance of the resonator.
  • Embodiments of the present invention will be described in detail below with reference to FIGS. 1A-1C through FIGS. 9A-9C.
  • Substrate the specific material can be silicon, silicon carbide, sapphire, silicon dioxide, or other silicon-based materials.
  • the material may be aluminum nitride, silicon nitride, polysilicon, silicon dioxide, amorphous silicon, boron-doped silicon dioxide, and other silicon-based materials.
  • Lithium oxide and other materials can also contain rare earth element doped materials with a certain atomic ratio of the above materials, such as doped aluminum nitride, and doped aluminum nitride contains at least one rare earth element, such as scandium (Sc), yttrium ( Y), magnesium (Mg), titanium (Ti), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium ( Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (T
  • the material can be selected from molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or the composite of the above metals or their alloys.
  • the first bottom electrode layer, the material can be selected from molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or a composite of the above metals or their alloys.
  • the second bottom electrode layer the material of which can be selected from molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or a composite of the above metals or their alloys.
  • the materials of the second bottom electrode layer and the first bottom electrode layer may be the same or different.
  • a gap layer in the bottom electrode which may be a gap layer, or a vacuum layer, or a gap layer filled with other gaseous media.
  • Top electrode the material can be selected from molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or the composite of the above metals or their alloys.
  • the material of the top electrode can be the same or different from that of the bottom electrode.
  • the first top electrode layer the material of which can be selected from molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or a composite of the above metals or their alloys.
  • the first bottom electrode layer and the first top electrode layer may be referred to as a first electrode layer.
  • the second top electrode layer the material of which can be selected from molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or a composite of the above metals or their alloys.
  • the materials of the second top electrode layer and the first top electrode layer may be the same or different.
  • the second bottom electrode layer and the second top electrode layer may be referred to as second electrode layers.
  • a gap layer in the top electrode which can be a gap layer, or a vacuum layer, or a gap layer filled with other gaseous media.
  • An insulating layer which plays an electrical insulating role, such as one of silicon dioxide, silicon nitride, silicon carbide, and sapphire, or the thermal conductivity of the insulating layer material is not less than 0.2 W/cm ⁇ K.
  • the thermal conductivity of the electrode material is generally good, and the heat generated by the resonator is mainly transferred to the support layer 110 through the bottom electrode 130 , and then transferred to the substrate 100 to be dissipated.
  • the heat transfer efficiency is high, the power capacity that the resonator can withstand is also high. Therefore, in the present invention, heat conduction is optimized by arranging the positions of the top and bottom electrodes.
  • FIG. 1A-1C are a schematic top view of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention, a schematic cross-sectional view along line AA' in FIG. 1A , and a schematic cross-sectional view along line BB' in FIG. 1A , respectively. picture.
  • the piezoelectric layer 120 is a single-crystal piezoelectric layer, a support layer 110 is disposed between the lower surface of the piezoelectric layer 120 and the upper surface of the substrate 100 , and the piezoelectric layer 120 is generally parallel to the substrate 100 . . Furthermore, as shown, the support layer includes a recess in which the bottom electrode is disposed.
  • the top electrode is a gap electrode, which includes a first top electrode layer 1401 and a second top electrode layer 1402 and a gap layer 1405 disposed between the two electrode layers;
  • the bottom electrode is also a gap electrode , which includes a first bottom electrode layer 1301 and a second bottom electrode layer 1302 and a void layer 1305 disposed between the two electrode layers.
  • the first bottom electrode layer 1301 and the first top electrode layer 1401 are in surface contact with the lower surface and the upper surface of the piezoelectric layer, respectively.
  • each gap electrode has only one gap layer, a plurality of gap layers stacked in the thickness direction of the resonator may be provided.
  • the alternating electric field is applied to the piezoelectric layer 120 through the electrodes. Due to the coupling and mutual conversion of acoustic and electric energy, current will pass through the electrodes.
  • the bottom electrodes all have a double-layer electrode parallel structure, so the electrical loss of the resonator can be effectively reduced.
  • the piezoelectric layer Under the excitation of the alternating electric field, the piezoelectric layer generates sound waves. When the sound waves are conducted in the upward and downward directions to the interface between the void layers 1305/1405 and the first electrode layers 1301/1401 located in the top and bottom electrodes, the sound waves are generated. The energy will be reflected back to the piezoelectric layer 120 (because the acoustic impedance of the air and the electrodes are greatly mismatched) and will not enter the second electrode layer 1302/1402.
  • the electrode structure containing the void layer in the present invention can significantly reduce the electrical loss of the resonator (represented by increasing the Q value at and near the series resonant frequency), and on the other hand, the air gap has a negative impact on the top and bottom electrodes.
  • the second electrode layer 1302/1402 acts as an acoustic isolation, thereby substantially avoiding the negative effects of the second electrode layer 1302/1402 on the performance of the resonator (such as changes in resonant frequency and electromechanical coupling coefficient).
  • the height of the void layer can be chosen to be larger than the typical amplitude of the resonator (about 10 nm), in one embodiment of the present invention, the height of the void layer is This is beneficial to the resonator when the resonator operates at high power, the second electrode layer 1302/1402 and the resonant cavity (this embodiment is a composite of the first bottom electrode layer 1301, the piezoelectric layer 120, and the first top electrode layer 1401). structure) acoustic energy decoupling.
  • FIGS. 2A-2C are a schematic top view of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention, a schematic cross-sectional view along line AA' in FIG. 2A, and a schematic cross-sectional view along line BB' in FIG. 2A, respectively
  • the top electrode is a gap electrode
  • the bottom electrode 130 is not a gap electrode.
  • 3A-3C are a schematic top view of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention, a schematic cross-sectional view along the line AA' in FIG. 3A, and a schematic cross-section along the line BB' in FIG. 3A, respectively
  • the bottom electrode is a gap electrode
  • the top electrode 140 is not a gap electrode.
  • gap electrodes described in connection with FIGS. 1A-1C also apply to the structures shown in FIGS. 2A-2C and 3A-3C as long as gap electrodes are provided.
  • the support layer 110 is provided with a recess
  • the bottom electrode is provided in the recess
  • the upper and lower sides of the second bottom electrode layer 1302 are respectively the gap layer 1305 and a cavity that is part of the recess.
  • no cavity may be provided, and Figures 4A-4C illustrate such an embodiment.
  • FIG. 4A-4C are a schematic top view of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention, a schematic cross-sectional view along line AA' in FIG. 4A and a schematic cross-sectional view along line BB' in FIG. 4A , respectively.
  • the top electrode may also not be a gap electrode.
  • the second bottom electrode layer 1302 covers the bottom of the recess, in other words, there is no cavity on the lower side of the second bottom electrode layer 1302 .
  • the void layer 1305 in the bottom electrode itself acts as the acoustic mirror of the resonator, the top electrode (the first top electrode layer in the case of the gap electrode), the first bottom electrode layer 1301, the piezoelectric layer 120 and the void layer 1305
  • the overlapping area in the thickness direction of the resonator constitutes the effective area of the resonator.
  • FIG. 5A-5C are a schematic top view of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention, a schematic cross-sectional view along line AA' in FIG. 5A and a schematic cross-sectional view along line BB' in FIG. 5A , respectively Figure, where the top and bottom electrodes are both gap electrodes. As can be appreciated, in Figures 5A-5C, only one of the top and bottom electrodes may be a gap electrode.
  • FIGS. 5A-5C compared with the structures shown in FIGS. 1A-1C , the difference lies in that, in FIGS. 5A-5C , the electrode connecting ends of the top electrode and the bottom electrode are provided with bridge structures, while the non-electrode connecting ends are provided with bridge structures.
  • only one electrode may be provided with bridge structures and cantilever structures.
  • the acoustic wave can be transmitted from the first electrode layer 1301/1401 to the second electrode layer 1302/1402 during the propagation process, resulting in partial deterioration of the performance of the resonator .
  • the second electrode layer 1302/1402 can be isolated from the acoustic coupling layer by arranging the cantilever structure at the non-connecting end of the electrode and the bridge structure at the connecting end of the electrode, so as to improve the acoustic performance of the resonator including the Q value.
  • FIGS. 6A-6C are a schematic top view of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention, a schematic cross-sectional view along line AA' in FIG. 6A, and a schematic cross-sectional view along line BB' in FIG. 6A, respectively Figure, where the top and bottom electrodes are both gap electrodes.
  • the bottom electrode may not be a gap electrode, and the bottom electrode may also adopt the structure shown in FIGS. 4A-4C.
  • FIGS. 6A-6C compared with the structures shown in FIGS. 1A-1C , the difference is that in FIGS. 6A-6C , the non-electrode connecting end of the top electrode is provided with a cantilever structure. Setting the cantilever structure is beneficial to isolate the second electrode layer 1402 from the acoustic coupling layer, so as to improve the acoustic performance of the resonator including the Q value.
  • FIGS. 7A-7C are a schematic top view of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention, a schematic cross-sectional view along line AA' in FIG. 7A, and a schematic cross-section along line BB' in FIG. 7A, respectively Figure, where the top and bottom electrodes are both gap electrodes.
  • the bottom electrode may not be a gap electrode, and the bottom electrode may also adopt the structure shown in FIGS. 4A-4C.
  • FIGS. 7A-7C compared with the structures shown in FIGS. 6A-6C , the difference is that, in FIGS. 7A-7C , the electrode connecting end of the top electrode is further provided with a bridge structure. Providing the bridge structure and the cantilever structure is beneficial to isolate the second electrode layer 1402 from the acoustic coupling layer, so as to improve the acoustic performance including the Q value of the resonator.
  • FIG. 8A-8C are a schematic top view of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention, a schematic cross-sectional view along line AA' in FIG. 8A, and a schematic cross-sectional view along line BB' in FIG. 8A, respectively Figure, where the top and bottom electrodes are both gap electrodes.
  • FIGS. 8A-8C compared with the structures shown in FIGS. 1A-1C , the difference is that in FIGS. 8A-8C , the non-electrode connecting end of the bottom electrode is also provided with a cantilever structure.
  • the provision of the cantilever structure is beneficial to isolate the second electrode layer 1302/1402 from the acoustic coupling layer, so as to improve the acoustic performance including the Q value of the resonator.
  • FIGS. 9A-9C are a schematic top view of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention, a schematic cross-sectional view along line AA' in FIG. 9A and a schematic cross-section along line BB' in FIG. 9A , respectively Figure, where the top and bottom electrodes are both gap electrodes.
  • FIGS. 9A-9C compared with the structures shown in FIGS. 8A-8C , the difference is that in FIGS. 9A-9C , the bottom of the support layer is flat.
  • the bottom electrode is an electrode with interference structures such as cantilever and bridge structures
  • the deposited sacrificial layer material is ground flat. After the sacrificial layer material is released, a flat bottom surface of the cavity 112 will be obtained, as shown in FIG. 9B shown. If not ground, the bottom surface of the cavity 112 with the stepped surface as shown in Figs. 5B and 8B will be obtained.
  • the symmetry of the electrodes on the upper and lower sides of the piezoelectric layer can also be considered.
  • both the bottom electrode and the top electrode are gap electrodes, and the thicknesses of the first top electrode layer 1401 and the first bottom electrode layer 1301 are the same.
  • the bottom electrode and the top electrode are both gap electrodes, the thicknesses of the first top electrode layer 1401 and the first bottom electrode layer 1301 are the same, and the second top electrode layer 1402 and the second bottom electrode layer 1302 of the same thickness.
  • the bottom electrode and the top electrode are both gap electrodes, arranged centrally symmetrically with respect to each other in a cross-section parallel to the thickness direction of the resonator and passing through the electrode connections of the top and bottom electrodes, eg, see Figures 1B, 4B, 5B, 8B, 9B.
  • the thickness of the first electrode layer is smaller than the thickness of the second electrode layer, which not only corresponds to the high operating frequency requirement (the thickness of the first electrode layer is small), but also helps In order to improve the conductivity of the electrode (the thickness of the second electrode layer is large).
  • the non-electrode connection ends of the bottom electrodes are embedded in the support layer 110 , and the bottom electrodes embedded in the support layer are respectively in the upper and lower directions parallel to the thickness direction of the resonator. It is in surface contact with the piezoelectric layer 120 and the support layer 110 . 1A-1C, the heat generated on the resonator can be efficiently transferred to the support layer 110 and the substrate 100, so as to improve the power capacity of the resonator.
  • a bulk acoustic wave resonator is fabricated based on a POI substrate.
  • the insulating layer can better protect the single-crystal piezoelectric film (ie, the single-crystal piezoelectric layer), thereby reducing or even avoiding the damage to the single-crystal piezoelectric film during the subsequent removal of the auxiliary substrate. damage, reduce or even avoid surface damage to the piezoelectric film, so as to obtain a bulk acoustic wave resonator with excellent performance.
  • the existence of the insulating layer is also conducive to the diversification of the auxiliary substrate removal scheme and simplify the device processing process.
  • FIGS. 10A-10C are a schematic top view, a schematic cross-sectional view along line AA' in FIG. 10A, and a schematic cross-sectional view along line BB' in FIG. 10A of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention, It is shown therein that at least a portion of the upper surface of the piezoelectric layer is provided with an insulating layer 150 (which is part of the insulating layer of the POI). As shown in FIGS. 10A-10C , in a more specific embodiment, the insulating layer 150 is disposed at least between the top electrode 140 and the piezoelectric layer 120 in a region corresponding to a portion of the top electrode 140 outside the effective region.
  • the material of the insulating layer 150 is selected from one of silicon dioxide, silicon nitride, silicon carbide, and sapphire, or the thermal conductivity of the material of the insulating layer is not less than 0.2 W/cm ⁇ K.
  • the gap electrode when the top electrode or the bottom electrode is a gap electrode, the gap electrode includes a first electrode layer and a second electrode that are stacked in the thickness direction of the resonator and connected in parallel to each other.
  • the layer, further, the lower surface and the upper surface of the piezoelectric layer 120, and the first electrode layer and the second electrode layer have portions that are both parallel to each other within the effective area of the resonator.
  • the effective area of the resonator refers to the area constituted by the overlapping area of the piezoelectric layer, the top electrode, the bottom electrode and the acoustic mirror in the thickness direction of the resonator.
  • the top electrode and the bottom electrode are both gap electrodes, and the parts of the top electrode and the bottom electrode within the active area are symmetrically arranged about the center of the active area of the resonator.
  • the center of the effective area of the resonator refers to a point located at the center of the effective area in a plan view of the effective area and on the median line of the piezoelectric layer in the thickness direction of the piezoelectric layer.
  • the symmetrical arrangement of the top and bottom electrodes of the resonator structure helps to weaken the parasitic mode of the resonator, improve its Q value, and optimize the performance of the resonator.
  • each numerical range except that it is clearly indicated that it does not include the endpoint value, can be the endpoint value, and can also be the median value of each numerical range, and these are all within the protection scope of the present invention. .
  • upper and lower are relative to the bottom surface of the base of the resonator.
  • the side close to the bottom surface is the lower side, and the side away from the bottom surface is the upper side.
  • inner and outer are relative to the center of the effective area of the resonator in the lateral direction or radial direction, one side or one end of a component close to the center of the effective area is the inner or inner end, and the component The side or end away from the center of the effective area is the outer or outer end.
  • being located on the inside of the position means being between the position and the center of the effective area in the lateral or radial direction, and being located outside of the position means being further away from the position in the lateral or radial direction than the position Effective regional center.
  • BAW resonators may be used to form filters or electronic devices.
  • a bulk acoustic wave resonator comprising:
  • the single crystal piezoelectric layer is arranged between the bottom electrode and the top electrode,
  • a support structure is arranged between the lower surface of the piezoelectric layer and the upper surface of the substrate, and the piezoelectric layer and the substrate are generally arranged in parallel;
  • the bottom electrode and/or the top electrode is a gap electrode, and the gap electrode has at least one gap layer, and in the thickness direction of the gap electrode, there is a distance between the gap layer and the top surface and the bottom surface of the gap electrode;
  • the support structure includes a recess in which the bottom electrode is disposed.
  • the gap electrode has a gap layer.
  • the gap electrode includes a first electrode layer and a second electrode layer that are stacked in the thickness direction of the resonator and are connected in parallel with each other, the gap layer is arranged between the first electrode layer and the second electrode layer, and the first electrode layer is A layer is in surface contact with the piezoelectric layer.
  • both the bottom electrode and the top electrode are gap electrodes
  • the thicknesses of the first electrode layers on the upper and lower sides of the piezoelectric layer are the same.
  • the thicknesses of the second electrode layers on the upper and lower sides of the piezoelectric layer are the same.
  • top and bottom electrodes on the upper and lower sides of the piezoelectric layer are arranged symmetrically with respect to each other in a cross-section parallel to the thickness direction of the resonator and passing through the electrode connecting portions of the top and bottom electrodes at the same time.
  • the thickness of the first electrode layer is smaller than the thickness of the second electrode layer.
  • the bottom electrode is a gap electrode, the gap layer is in the recess;
  • the void layer in the bottom electrode constitutes the acoustic mirror, wherein: the top electrode, the first electrode layer of the bottom electrode, the overlapping area of the piezoelectric layer and the void layer in the thickness direction of the resonator constitute the effective area of the resonator.
  • the concave portion includes a cavity, and the upper and lower sides of the second electrode layer of the bottom electrode are a void layer and the cavity respectively.
  • the second electrode layer of the bottom electrode covers the bottom of the recess.
  • the thickness of the void layer is In the range.
  • the non-electrode connection end of the bottom electrode is embedded in the support structure, and the bottom electrode embedded in the support structure is in contact with the piezoelectric layer and the support structure in the vertical direction parallel to the thickness direction of the resonator.
  • the top and/or bottom electrodes are flat electrodes.
  • the top electrode and/or the bottom electrode is provided with a bridge wing structure, and the bridge wing structure includes a bridge structure and/or a cantilever structure.
  • the overlapping area of the acoustic mirror, the bottom electrode, the piezoelectric layer and the top electrode in the thickness direction of the resonator constitutes an effective area of the resonator
  • At least a portion of the upper surface of the piezoelectric layer is provided with an insulating layer.
  • the insulating layer is at least disposed between the lower surface of the top electrode and the upper surface of the piezoelectric layer;
  • the material of the insulating layer is selected from one of silicon dioxide, silicon nitride, silicon carbide, and sapphire, or the thermal conductivity of the material of the insulating layer is not less than 0.2 W/cm ⁇ K.
  • the gap electrode includes a first electrode layer and a second electrode layer that are stacked in the thickness direction of the resonator and are connected in parallel to each other;
  • the lower surface and the upper surface of the piezoelectric layer, and the first electrode layer and the second electrode layer have portions parallel to each other in the effective area of the resonator.
  • the top and bottom electrodes are both gap electrodes
  • Portions of the top and bottom electrodes within the active area are symmetrically arranged with respect to the center of the active area of the resonator.
  • a filter comprising the bulk acoustic wave resonator of any one of 1-18.
  • An electronic device comprising the filter according to 19, or the bulk acoustic wave resonator according to any one of 1-18.
  • the electronic equipment here includes but is not limited to intermediate products such as RF front-end, filter and amplifier modules, and terminal products such as mobile phones, WIFI, and drones.

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

Abstract

提供一种体声波谐振器，包括：基底（100）；声学镜；底电极（130）；顶电极（140）；和单晶压电层（120），设置在底电极（130）与顶电极（140）之间，其中：压电层（120）的下表面与基底（100）的上表面之间设置有支撑结构（110），压电层（120）与基底（100）大体平行布置；底电极（130）和/或顶电极（140）为间隙电极，间隙电极具有至少一个空隙层（1305,1405），在间隙电极的厚度方向上，空隙层（1305,1405）与间隙电极的顶面与底面均存在距离；且支撑结构（110）包括凹部，底电极（130）设置在凹部中。还提供一种滤波器以及一种电子设备。

Description

单晶体声波谐振器、滤波器及电子设备 技术领域
本发明的实施例涉及半导体领域，尤其涉及一种单晶体声波谐振器，一种具有该谐振器的滤波器，以及一种电子设备。
背景技术
电子器件作为电子设备的基本元素，已经被广泛应用，其应用范围包括移动电话、汽车、家电设备等。此外，未来即将改变世界的人工智能、物联网、5G通讯等技术仍然需要依靠电子器件作为基础。
薄膜体声波谐振器(Film Bulk Acoustic Resonator，简称FBAR，又称为体声波谐振器，也称BAW)作为压电器件的重要成员正在通信领域发挥着重要作用，特别是FBAR滤波器在射频滤波器领域市场占有份额越来越大，FBAR具有尺寸小、谐振频率高、品质因数高、功率容量大、滚降效应好等优良特性，其滤波器正在逐步取代传统的声表面波(SAW)滤波器和陶瓷滤波器，在无线通信射频领域发挥巨大作用，其高灵敏度的优势也能应用到生物、物理、医学等传感领域。
薄膜体声波谐振器的结构主体为由底电极-压电薄膜或压电层-顶电极组成的“三明治”结构，即两层金属电极层之间夹一层压电材料。通过在两电极间输入正弦信号，FBAR利用逆压电效应将输入电信号转换为机械谐振，并且再利用压电效应将机械谐振转换为电信号输出。
传统的薄膜体声波谐振器中，压电层一般采用半导体薄膜沉积工艺(如溅射工艺)沉积在结构化的底电极上，压电薄膜不是平直结构，存在较大的应力；另外，沉积所得的压电薄膜呈多晶型的晶体结构，其中弯折处的晶体结构与平直处存在极大的不同，影响压电薄膜的机电耦合及传热性能的均一性；为了获得性能相对较好的压电薄膜，对底电极的形貌结构提出了非常苛刻的要求，比如电极边缘存在尽可能缓的斜坡，角度通常在10至20°之间，给加工造成了较大的困难；在底电极上制作用于提升谐振器性能的干涉结构(比如翼、桥等)也几乎是不可能的。这些因素限制了传统基于生长压电薄膜工艺的体声波谐振器性能受限。
此外，通信技术的快速发展要求滤波器工作频率不断提高，高工作频率意味着薄膜厚度尤其是电极的薄膜厚度，要进一步减小；然而电极薄膜厚度的减小带来的主要负面效应为电学损耗增加导致的谐振器Q值降低，尤其是串联谐振点及其频率附近处的Q值降低；相应地，高工作频率体声波滤波器 的性能也随着体声波谐振器的Q值降低而大幅恶化。
发明内容
为缓解或解决现有技术中的上述问题的至少一个方面，提出本发明。
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；
顶电极；和
单晶压电层，设置在底电极与顶电极之间，
其中：
压电层的下表面与基底的上表面之间设置有支撑结构，压电层与基底大体平行布置；
底电极和/或顶电极为间隙电极，所述间隙电极具有至少一个空隙层，在所述间隙电极的厚度方向上，所述空隙层与所述间隙电极的顶面与底面均存在距离；且
所述支撑结构包括凹部，所述底电极设置在所述凹部中。
本发明的实施例还涉及一种滤波器，包括上述的体声波谐振器。
本发明的实施例也涉及一种电子设备，包括上述的滤波器或者上述的谐振器。
附图说明
以下描述与附图可以更好地帮助理解本发明所公布的各种实施例中的这些和其他特点、优点，图中相同的附图标记始终表示相同的部件，其中：
图1A-1C分别为根据本发明的第一示例性实施例的体声波谐振器的俯视示意图、沿图1A中的AA’线的示意性截面图以及沿图1A中的BB’线的示意性截面图；
图2A-2C为根据本发明的第二示例性实施例的体声波谐振器的俯视示意图、沿图2A中的AA’线的示意性截面图以及沿图2A中的BB’线的示意性截面图；
图3A-3C为根据本发明的第三示例性实施例的体声波谐振器的俯视示意图、沿图3A中的AA’线的示意性截面图以及沿图3A中的BB’线的示意性截面图；
图4A-4C为根据本发明的第四示例性实施例的体声波谐振器的俯视示意图、沿图4A中的AA’线的示意性截面图以及沿图4A中的BB’线的示意性截面图；
图5A-5C为根据本发明的第五示例性实施例的体声波谐振器的俯视示意图、沿图5A中的AA’线的示意性截面图以及沿图5A中的BB’线的示意性截面图；
图6A-6C为根据本发明的第六示例性实施例的体声波谐振器的俯视示意图、沿图6A中的AA’线的示意性截面图以及沿图6A中的BB’线的示意性截面图；
图7A-7C为根据本发明的第七示例性实施例的体声波谐振器的俯视示意图、沿图7A中的AA’线的示意性截面图以及沿图7A中的BB’线的示意性截面图；
图8A-8C为根据本发明的第八示例性实施例的体声波谐振器的俯视示意图、沿图8A中的AA’线的示意性截面图以及沿图8A中的BB’线的示意性截面图；
图9A-9C为根据本发明的第九示例性实施例的体声波谐振器的俯视示意图、沿图9A中的AA’线的示意性截面图以及沿图9A中的BB’线的示意性截面图；
图10A-10C为根据本发明的第十示例性实施例的体声波谐振器的俯视示意图、沿图10A中的AA’线的示意性截面图以及沿图10A中的BB’线的示意性截面图，其中示出了绝缘层。
具体实施方式
下面通过实施例，并结合附图，对本发明的技术方案作进一步具体的说明。在说明书中，相同或相似的附图标号指示相同或相似的部件。下述参照附图对本发明实施方式的说明旨在对本发明的总体发明构思进行解释，而不应当理解为对本发明的一种限制。发明的一部分实施例，而并不是全部的实施例。基于本发明中的实施例，本领域普通技术人员所获得的所有其他实施例，都属于本发明保护的范围。
本发明提出了一种经POI(Piezoelectrics on Insulator，绝缘体上的单晶压电层)衬底制作的体声波谐振器结构。POI衬底包括辅助衬底、单晶压电层以及设置在单晶压电层与辅助衬底之间的绝缘层。基于本发明的体声波谐振器的底电极和/或顶电极为间隙电极或中空电极，间隙电极具有设置在第一电极层与第二电极层之间的空隙层，而第一电极层与第二电极层彼此电连接，这使得整个间隙电极的导电性提高。通过设置间隙电极，可以提高谐振器的电学性能和声学性能。
此外，经POI衬底制作的体声波谐振器，相较于传统的谐振器，压电层两侧的电极结构并不影响压电层的本征性能，这有利于电极的多样化结构设计，有利于提高谐振器的综合性能。
下面参照图1A-1C直至图9A-9C具体说明本发明的实施例。
本发明的附图中的附图标记示例性说明如下：
100：基底，具体材料可选为硅、碳化硅、蓝宝石、二氧化硅，或其他硅基材料。
110：支撑层或支撑结构，材料可以为氮化铝、氮化硅、多晶硅、二氧化硅、无定形硅、硼掺杂二氧化硅及其他硅基材料等。
112：空腔。
120：单晶压电层，可选单晶氮化铝、单晶氮化镓、单晶铌酸锂、单晶锆钛酸铅、单晶铌酸钾、单晶石英薄膜、或者单晶钽酸锂等材料，还可包含上述材料的一定原子比的稀土元素掺杂材料，例如可以是掺杂氮化铝，掺杂氮化铝至少含一种稀土元素，如钪(Sc)、钇(Y)、镁(Mg)、钛(Ti)、镧(La)、铈(Ce)、镨(Pr)、钕(Nd)、钷(Pm)、钐(Sm)、铕(Eu)、钆(Gd)、铽(Tb)、镝(Dy)、钬(Ho)、铒(Er)、铥(Tm)、镱(Yb)、镥(Lu)等。
122：释放孔，用于释放声学镜空腔中的牺牲层材料。
130：底电极，材料可选钼、钌、金、铝、镁、钨、铜，钛、铱、锇、铬或以上金属的复合或其合金等。
1301：第一底电极层，材料可选钼、钌、金、铝、镁、钨、铜，钛、铱、锇、铬或以上金属的复合或其合金等。
1302：第二底电极层，材料可选钼、钌、金、铝、镁、钨、铜，钛、铱、锇、铬或以上金属的复合或其合金等。第二底电极层与第一底电极层的材料可以相同，也可以不同。
1305：底电极中的间隙层，其可以是空隙层，或者真空层，或者填充了其他气体介质的空隙层。
140：顶电极，材料可选钼、钌、金、铝、镁、钨、铜，钛、铱、锇、 铬或以上金属的复合或其合金等。顶电极的材料可以与底电极的材料相同或不同。
1401：第一顶电极层，材料可选钼、钌、金、铝、镁、钨、铜，钛、铱、锇、铬或以上金属的复合或其合金等。第一底电极层和第一顶电极层可以称为第一电极层。
1402：第二顶电极层，材料可选钼、钌、金、铝、镁、钨、铜，钛、铱、锇、铬或以上金属的复合或其合金等。第二顶电极层与第一顶电极层的材料可以相同，也可以不同。第二底电极层与第二顶电极层可以称为第二电极层。
1403：悬翼结构限定的空隙。
1404：悬翼结构。
1405：顶电极中的间隙层，其可以是空隙层，或者真空层，或者填充了其他气体介质的空隙层。
150：绝缘层，起到电绝缘的作用，例如二氧化硅、氮化硅、碳化硅、蓝宝石中的一种，或者所述绝缘层的材料的导热系数不小于0.2W/cm·K。
电极材料的导热性能通常较好，谐振器产生的热量主要通过底电极130传至支撑层110，然后传至基底100耗散掉。当热量传输效率较高时，谐振器能承受的功率容量也较高。因此，在本发明中，通过安排顶电极与底电极的位置，来优化热传导。
图1A-1C分别为根据本发明的一个示例性实施例的体声波谐振器的俯视示意图、沿图1A中的AA’线的示意性截面图以及沿图1A中的BB’线的示意性截面图。
如图1A-1C所示，压电层120为单晶压电层，压电层120的下表面与基底100的上表面之间设置有支撑层110，压电层120与基底100大体平行布置。此外，如图所示，支撑层包括凹部，底电极设置在凹部中。
如图1A-1C所示，顶电极为间隙电极，其包括第一顶电极层1401和第二顶电极层1402以及设置在该两个电极层之间的空隙层1405；底电极也为间隙电极，其包括第一底电极层1301和第二底电极层1302以及设置在该两个电极层之间的空隙层1305。在图1A-1C中，第一底电极层1301以及第一顶电极层1401分别与所述压电层的下表面和上表面形成面接触。
虽然在图示的实施例中，每个间隙电极仅有一个空隙层，但是也可以设置多个在谐振器的厚度方向上层叠的多个空隙层。
当图1A-1C所示的谐振器工作时，交变电场通过电极施加在压电层120上，由于声电能量耦合并相互转化，电极中会有电流通过，由于本实施例的顶电极、底电极都具有双层电极并联结构，因此可以有效减小谐振器的电学 损耗。
在交变电场的激励下，压电层产生声波，当声波向上、下两个方向传导至位于顶电极、底电极中的空隙层1305/1405和第一电极层1301/1401的界面时，声波能量会被反射回压电层120(因为空气和电极的声阻抗不匹配程度极大)，并不会进入第二电极层1302/1402。
本发明中含有空隙层的电极结构，一方面可显著降低谐振器的电学损耗(表现为提升串联谐振频率处及其附近Q值的提高)，另一方面空气间隙对顶电极、底电极的第二电极层1302/1402起到了声学隔离作用，从而基本避免第二电极层1302/1402对谐振器性能造成的负面影响(如谐振频率和机电耦合系数的改变)。
空隙层的高度可以选择大于谐振器的典型振幅(约10nm)，在本发明的一个实施例中，空隙层的高度在
Figure PCTCN2021139954-appb-000001
的范围内，这有利于谐振器在大功率工作时第二电极层1302/1402与谐振腔(此实施例为第一底电极层1301、压电层120、第一顶电极层1401组成的复合结构)的声学能量解耦。
图2A-2C分别为根据本发明的一个示例性实施例的体声波谐振器的俯视示意图、沿图2A中的AA’线的示意性截面图以及沿图2A中的BB’线的示意性截面图，其中顶电极为间隙电极，而底电极130不是间隙电极。图3A-3C分别为根据本发明的一个示例性实施例的体声波谐振器的俯视示意图、沿图3A中的AA’线的示意性截面图以及沿图3A中的BB’线的示意性截面图，其中底电极为间隙电极，而顶电极140不是间隙电极。
如能够理解的，只要设置了间隙电极，在结合图1A-1C所说明的使用间隙电极的好处和优点也适用于图2A-2C以及图3A-3C所示的结构。
在以上的实施例中，支撑层110设置有凹部，而底电极设置在该凹部中，而且，在底电极为间隙电极的情况下，第二底电极层1302的上下两侧分别是空隙层1305以及作为凹部的一部分的空腔。但是，也可以不设置空腔，图4A-4C示出了这样的实施例。
图4A-4C分别为根据本发明的一个示例性实施例的体声波谐振器的俯视示意图、沿图4A中的AA’线的示意性截面图以及沿图4A中的BB’线的示意性截面图，其中顶电极和底电极均为间隙电极。如能够理解的，在图4A-4C中，顶电极也可不是间隙电极。
如图4B所示，第二底电极层1302覆盖所述凹部的底部，换言之，在第二底电极层1302的下侧并不存在空腔。此时，底电极中的空隙层1305本身作为谐振器的声学镜，顶电极(是间隙电极的情况下为第一顶电极层)、第一底电极层1301、压电层120和空隙层1305在谐振器的厚度方向上的重叠 区域构成谐振器的有效区域。
图5A-5C分别为根据本发明的一个示例性实施例的体声波谐振器的俯视示意图、沿图5A中的AA’线的示意性截面图以及沿图5A中的BB’线的示意性截面图，其中顶电极和底电极均为间隙电极。如能够理解的，在图5A-5C中，顶电极和底电极可以仅有一个是间隙电极。
在图5A-5C中，相较于图1A-1C所示的结构，不同在于，在图5A-5C中，顶电极和底电极的电极连接端设置有桥结构，而在非电极连接端设置有悬翼结构。如能够理解的，可以仅仅一个电极设置有桥结构和悬翼结构。
在第一电极层1301/1401和第二电极层1302/1402边缘连接部位，声波传播过程中能从第一电极层1301/1401传至第二电极层1302/1402，导致谐振器性能的部分恶化。通过在电极的非连接端设置悬翼结构，在电极连接端设置桥结构，可以将第二电极层1302/1402隔绝于声学耦合层之外，以提高谐振器包括Q值在内的声学性能。
图6A-6C分别为根据本发明的一个示例性实施例的体声波谐振器的俯视示意图、沿图6A中的AA’线的示意性截面图以及沿图6A中的BB’线的示意性截面图，其中顶电极和底电极均为间隙电极。如能够理解的，在图6A-6C中，底电极可以不是间隙电极，底电极也可以采用图4A-4C所示的结构。
在图6A-6C中，相较于图1A-1C所示的结构，不同在于，在图6A-6C中，顶电极的非电极连接端设置有悬翼结构。设置悬翼结构有利于将第二电极层1402隔绝于声学耦合层之外，以提高谐振器包括Q值在内的声学性能。
图7A-7C分别为根据本发明的一个示例性实施例的体声波谐振器的俯视示意图、沿图7A中的AA’线的示意性截面图以及沿图7A中的BB’线的示意性截面图，其中顶电极和底电极均为间隙电极。如能够理解的，在图7A-7C中，底电极可以不是间隙电极，底电极也可以采用图4A-4C所示的结构。
在图7A-7C中，相较于图6A-6C所示的结构，不同在于，在图7A-7C中，顶电极的电极连接端还设置有桥结构。设置桥结构以及悬翼结构有利于将第二电极层1402隔绝于声学耦合层之外，以提高谐振器包括Q值在内的声学性能。
图8A-8C分别为根据本发明的一个示例性实施例的体声波谐振器的俯视示意图、沿图8A中的AA’线的示意性截面图以及沿图8A中的BB’线的示意性截面图，其中顶电极和底电极均为间隙电极。
在图8A-8C中，相较于图1A-1C所示的结构，不同在于，在图8A-8C中，底电极的非电极连接端也设置有悬翼结构。设置悬翼结构有利于将第二电极层1302/1402隔绝于声学耦合层之外，以提高谐振器包括Q值在内的声 学性能。
图9A-9C分别为根据本发明的一个示例性实施例的体声波谐振器的俯视示意图、沿图9A中的AA’线的示意性截面图以及沿图9A中的BB’线的示意性截面图，其中顶电极和底电极均为间隙电极。
在图9A-9C中，相较于图8A-8C所示的结构，不同在于，在图9A-9C中，支撑层的底部为平坦的。针对底电极为含有悬翼、桥结构等干涉结构的电极时，沉积支撑层材料之前，对沉积的牺牲层材料磨平，牺牲层材料释放以后将得到平的空腔112的底面，如图9B所示。如果不磨平，将得到如图5B和图8B所示的有台阶面的空腔112的底面。
在本发明中，还可以考虑压电层上下两侧的电极的对称性。
在一个实施例中，底电极和顶电极均为间隙电极，且第一顶电极层1401和第一底电极层1301的厚度相同。
在进一步可选的实施例中，底电极和顶电极均为间隙电极，第一顶电极层1401和第一底电极层1301的厚度相同，且第二顶电极层1402和第二底电极层1302的厚度相同。
在可选的实施例中，底电极和顶电极均为间隙电极，在平行于谐振器的厚度方向且同时通过顶电极和底电极的电极连接部的截面中，关于彼此中心对称布置，例如参见图1B，4B，5B，8B，9B。
在本发明的可选实施例中，在间隙电极中，第一电极层的厚度小于第二电极层的厚度，这不仅与高工作频率要求对应(第一电极层的厚度小)，而且有助于提高电极的导电性(第二电极层的厚度大)。
此外，例如在图1A-1C所示的实施例中，底电极的非电极连接端埋设在支撑层110中，埋设在支撑层中的底电极在平行于谐振器的厚度方向的上下方向上分别与压电层120与支撑层110面接触。采用图1A-1C的结构，可以使谐振器上产生的热量能够高效的传至支撑层110及基底100，以提高谐振器的功率容量。
在本发明中，基于POI衬底制作体声波谐振器。在谐振器转移加工过程中，绝缘层能够更好的保护单晶压电薄膜(即单晶压电层)，从而可以减小甚至避免后续去除辅助衬底的过程中对单晶压电薄膜的损伤，减小甚至避免对压电薄膜的表面损伤，以得到性能优异的体声波谐振器。另外，绝缘层的存在，也有利于辅助衬底去除方案的多样化，简化器件加工工艺。
图10A-10C为根据本发明的示例性实施例的体声波谐振器的俯视示意图、沿图10A中的AA’线的示意性截面图以及沿图10A中的BB’线的示意性截面图，其中示出了压电层的上表面的至少一部分设置有绝缘层150(其为 POI的绝缘层的一部分)。如图10A-10C所示，在更具体的实施例中，在顶电极140的处于有效区域之外的部分对应的区域，绝缘层150至少设置在顶电极140与压电层120之间。
为便于导热，所述绝缘层150的材料选自二氧化硅、氮化硅、碳化硅、蓝宝石中的一种，或者所述绝缘层的材料的导热系数不小于0.2W/cm·K。
在本发明中，例如，参见图1A-1C等，当顶电极或底电极为间隙电极时，间隙电极包括在谐振器的厚度方向上层叠设置且彼此并联连接的第一电极层和第二电极层，进一步的，压电层120的下表面和上表面，与所述第一电极层和第二电极层在谐振器的有效区域内具有彼此均平行的部分。
在本发明中，谐振器的有效区域是指压电层、顶电极、底电极和声学镜在谐振器的厚度方向上的重叠区域构成的区域。
在进一步的实施例中，顶电极和底电极均为间隙电极，且顶电极和底电极在有效区域内的部分关于谐振器的有效区域中心对称布置。这里，谐振器的有效区域中心是指：在有效区域的俯视图中处于有效区域的型心且在压电层的厚度方向上处于压电层的中分线上的点。顶、底电极对称的谐振器结构布置，有助于弱化谐振器寄生模式，提高其Q值，使谐振器性能得到优化。
需要指出的是，在本发明中，各个数值范围，除了明确指出不包含端点值之外，除了可以为端点值，还可以为各个数值范围的中值，这些均在本发明的保护范围之内。
在本发明中，上和下是相对于谐振器的基底的底面而言的，对于一个部件，其靠近该底面的一侧为下侧，远离该底面的一侧为上侧。
在本发明中，内和外是相对于谐振器的有效区域中心在横向方向或者径向方向上而言的，一个部件的靠近有效区域中心的一侧或一端为内侧或内端，而该部件的远离有效区域中心的一侧或一端为外侧或外端。对于一个参照位置而言，位于该位置的内侧表示在横向方向或径向方向上处于该位置与有效区域中心之间，位于该位置的外侧表示在横向方向或径向方向上比该位置更远离有效区域中心。
如本领域技术人员能够理解的，根据本发明的体声波谐振器可以用于形成滤波器或电子设备。
基于以上，本发明提出了如下技术方案：
1、一种体声波谐振器，包括：
基底；
声学镜；
底电极；
顶电极；和
单晶压电层，设置在底电极与顶电极之间，
其中：
压电层的下表面与基底的上表面之间设置有支撑结构，压电层与基底大体平行布置；
底电极和/或顶电极为间隙电极，所述间隙电极具有至少一个空隙层，在所述间隙电极的厚度方向上，所述空隙层与所述间隙电极的顶面与底面均存在距离；且
所述支撑结构包括凹部，所述底电极设置在所述凹部中。
2、根据1所述的谐振器，其中：
所述间隙电极具有一个空隙层。
3、根据2所述的谐振器，其中：
所述间隙电极包括在谐振器的厚度方向上层叠设置且彼此并联连接的第一电极层和第二电极层，所述空隙层设置在第一电极层与第二电极层之间，第一电极层与所述压电层形成面接触。
4、根据3所述的谐振器，其中：
底电极和顶电极均为间隙电极；且
压电层上下两侧的第一电极层的厚度相同。
5、根据4所述的谐振器，其中：
压电层上下两侧的第二电极层的厚度相同。
6、根据5所述的谐振器，其中：
压电层上下两侧的顶电极与底电极，在平行于谐振器的厚度方向且同时通过顶电极和底电极的电极连接部的截面中，关于彼此中心对称布置。
7、根据3所述的谐振器，其中：
在间隙电极中，第一电极层的厚度小于第二电极层的厚度。
8、根据3所述的谐振器，其中：
底电极为间隙电极，所述空隙层处于所述凹部中；且
底电极中的所述空隙层构成所述声学镜，其中：顶电极，底电极的第一电极层，压电层和空隙层在谐振器的厚度方向上的重叠区域构成谐振器的有效区域。
9、根据8所述的谐振器，其中：
所述凹部包括空腔，所述底电极的第二电极层的上下两侧分别为空隙层与所述空腔。
10、根据8所述的谐振器，其中：
所述底电极的第二电极层覆盖所述凹部的底部。
11、根据1所述的谐振器，其中：
所述空隙层的厚度在
Figure PCTCN2021139954-appb-000002
的范围内。
12、根据1所述的谐振器，其中：
底电极的非电极连接端埋设在支撑结构中，埋设在支撑结构中的底电极在平行于谐振器的厚度方向的上下方向上分别与压电层与支撑结构面接触。
13、根据1-12中任一项所述的谐振器，其中：
顶电极和/或底电极为平直电极。
14、根据1-11中任一项所述的谐振器，其中：
顶电极和/或底电极设置有桥翼结构，所述桥翼结构包括桥结构和/或悬翼结构。
15、根据1-14中任一项所述的谐振器，其中：
声学镜、底电极、压电层和顶电极在谐振器的厚度方向上的重合区域构成谐振器的有效区域；
在有效区域之外，所述压电层的上表面的至少一部分设置有绝缘层。
16、根据15所述的谐振器，其中：
在顶电极的处于有效区域之外的部分对应的区域，所述绝缘层至少设置在顶电极的下表面与压电层的上表面之间；
所述绝缘层的材料选自二氧化硅、氮化硅、碳化硅、蓝宝石中的一种，或者所述绝缘层的材料的导热系数不小于0.2W/cm·K。
17、根据1所述的谐振器，其中：
所述间隙电极包括在谐振器的厚度方向上层叠设置且彼此并联连接的第一电极层和第二电极层；
所述压电层的下表面和上表面，与所述第一电极层和第二电极层在谐振器的有效区域内具有彼此均平行的部分。
18、根据17所述的谐振器，其中：
所述顶电极和底电极均为间隙电极；且
所述顶电极和底电极在有效区域内的部分关于谐振器的有效区域的中心对称布置。
19、一种滤波器，包括根据1-18中任一项所述的体声波谐振器。
20、一种电子设备，包括根据19所述的滤波器，或者根据1-18中任一项所述的体声波谐振器。
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。
尽管已经示出和描述了本发明的实施例，对于本领域的普通技术人员而言，可以理解在不脱离本发明的原理和精神的情况下可以对这些实施例进行变化，本发明的范围由所附权利要求及其等同物限定。

Claims (20)

  1. 一种体声波谐振器，包括：
    基底；
    声学镜；
    底电极；
    顶电极；和
    单晶压电层，设置在底电极与顶电极之间，
    其中：
    压电层的下表面与基底的上表面之间设置有支撑结构，压电层与基底大体平行布置；
    底电极和/或顶电极为间隙电极，所述间隙电极具有至少一个空隙层，在所述间隙电极的厚度方向上，所述空隙层与所述间隙电极的顶面与底面均存在距离；且
    所述支撑结构包括凹部，所述底电极设置在所述凹部中。
  2. 根据权利要求1所述的谐振器，其中：
    所述间隙电极具有一个空隙层。
  3. 根据权利要求2所述的谐振器，其中：
    所述间隙电极包括在谐振器的厚度方向上层叠设置且彼此并联连接的第一电极层和第二电极层，所述空隙层设置在第一电极层与第二电极层之间，第一电极层与所述压电层形成面接触。
  4. 根据权利要求3所述的谐振器，其中：
    底电极和顶电极均为间隙电极；且
    压电层上下两侧的第一电极层的厚度相同。
  5. 根据权利要求4所述的谐振器，其中：
    压电层上下两侧的第二电极层的厚度相同。
  6. 根据权利要求5所述的谐振器，其中：
    压电层上下两侧的顶电极与底电极，在平行于谐振器的厚度方向且同时通过顶电极和底电极的电极连接部的截面中，关于彼此中心对称布置。
  7. 根据权利要求3所述的谐振器，其中：
    在间隙电极中，第一电极层的厚度小于第二电极层的厚度。
  8. 根据权利要求3所述的谐振器，其中：
    底电极为间隙电极，所述空隙层处于所述凹部中；且
    底电极中的所述空隙层构成所述声学镜，其中：顶电极，底电极的第一电极层，压电层和空隙层在谐振器的厚度方向上的重叠区域构成谐振器的有效区域。
  9. 根据权利要求8所述的谐振器，其中：
    所述凹部包括空腔，所述底电极的第二电极层的上下两侧分别为空隙层与所述空腔。
  10. 根据权利要求8所述的谐振器，其中：
    所述底电极的第二电极层覆盖所述凹部的底部。
  11. 根据权利要求1所述的谐振器，其中：
    所述空隙层的厚度在
    Figure PCTCN2021139954-appb-100001
    的范围内。
  12. 根据权利要求1所述的谐振器，其中：
    底电极的非电极连接端埋设在支撑结构中，埋设在支撑结构中的底电极在平行于谐振器的厚度方向的上下方向上分别与压电层与支撑结构面接触。
  13. 根据权利要求1-12中任一项所述的谐振器，其中：
    顶电极和/或底电极为平直电极。
  14. 根据权利要求1-11中任一项所述的谐振器，其中：
    顶电极和/或底电极设置有桥翼结构，所述桥翼结构包括桥结构和/或悬翼结构。
  15. 根据权利要求1-14中任一项所述的谐振器，其中：
    声学镜、底电极、压电层和顶电极在谐振器的厚度方向上的重合区域构成谐振器的有效区域；
    在有效区域之外，所述压电层的上表面的至少一部分设置有绝缘层。
  16. 根据权利要求15所述的谐振器，其中：
    在顶电极的处于有效区域之外的部分对应的区域，所述绝缘层至少设置在顶电极的下表面与压电层的上表面之间；
    所述绝缘层的材料选自二氧化硅、氮化硅、碳化硅、蓝宝石中的一种，或者所述绝缘层的材料的导热系数不小于0.2W/cm·K。
  17. 根据权利要求1所述的谐振器，其中：
    所述间隙电极包括在谐振器的厚度方向上层叠设置且彼此并联连接的 第一电极层和第二电极层；
    所述压电层的下表面和上表面，与所述第一电极层和第二电极层在谐振器的有效区域内具有彼此均平行的部分。
  18. 根据权利要求17所述的谐振器，其中：
    所述顶电极和底电极均为间隙电极；且
    所述顶电极和底电极在有效区域内的部分关于谐振器的有效区域的中心对称布置。
  19. 一种滤波器，包括根据权利要求1-18中任一项所述的体声波谐振器。
  20. 一种电子设备，包括根据权利要求19所述的滤波器，或者根据权利要求1-18中任一项所述的体声波谐振器。
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CN117639713A (zh) * 2023-02-02 2024-03-01 北京芯溪半导体科技有限公司 体声波谐振器及其制造方法、滤波器和电子设备

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