Bulk acoustic wave resonator with acoustic resistance layer, assembly and manufacturing method thereof, filter and electronic device

Abstract

The present application relates to a bulk acoustic wave resonator, comprising: a substrate; an acoustic mirror; a bottom electrode; a piezoelectric layer; and a top electrode, wherein: an overlapping area of the top electrode, the piezoelectric layer, and the bottom electrode in a thickness direction of the resonator constitutes an effective area of the resonator; the piezoelectric layer comprises a first layer and a second layer, an acoustic resistance layer is arranged between the first layer and the second layer, the second layer is above the first layer, an inner edge of the acoustic resistance layer is on an inner side of a boundary of the acoustic mirror in a horizontal direction, an acoustic resistance of the acoustic resistance layer is different from an acoustic resistance of the piezoelectric layer; the resonator further comprises a channel or an opening that communicates the acoustic resistance layer with an outside. The present application also relates to a bulk acoustic wave resonator assembly, a method for manufacturing a bulk acoustic wave resonator, a filter, and an electronic device.

Description

Technical Field

[0001] Embodiments of the present invention relate to the semiconductor field, and more particularly to a bulk acoustic wave resonator and its components, a method for manufacturing a bulk acoustic wave resonator, a filter, and an electronic device. Background Technology

[0002] With the rapid development of 5G communication technology, the requirements for data transmission rates are becoming increasingly stringent. Corresponding to these data transmission rates are the high utilization rate of spectrum resources and the increasing complexity of the spectrum. The increasing complexity of communication protocols places stringent demands on the various performance characteristics of radio frequency (RF) systems. In the RF front-end module, RF filters play a crucial role, filtering out out-of-band interference and noise to meet the signal-to-noise ratio requirements of the RF system and communication protocols.

[0003] Traditional radio frequency filters, limited by their structure and performance, cannot meet the requirements of high-frequency communication. Thin-film bulk acoustic resonators (FBARs), as a novel MEMS device, have advantages such as small size, light weight, low insertion loss, wide bandwidth, and high quality factor, making them well-suited for the upgrading of wireless communication systems and making FBAR technology one of the research hotspots in the field of communication.

[0004] In existing filters, the passband characteristics are formed by the combined action of series and parallel resonators. This is achieved by setting different series resonant frequencies for the series resonators and adjusting the electromechanical coupling coefficient Kt of the series resonators. 2 The change in Kt can effectively improve the roll-off characteristics on the right side of the filter's passband. The filter uses a small Kt. 2 Resonators are easy to achieve good roll-off characteristics, but once the design specifications (bandwidth, insertion loss, out-of-band rejection, etc.) are determined, the Kt of the resonator becomes crucial. 2 This essentially confirms that filter bandwidth and good roll-off characteristics are contradictory. Under conventional architectures, it's difficult to achieve good roll-off characteristics in wide-bandwidth filter designs. Furthermore, given the fixed resonator stack in ordinary filters, modifying the resonator structure can reduce the Kt of a 50 Ohm resonator. 2 The change is only around ±0.5%, which has limited improvement on the filter's roll-off characteristics. Therefore, the Kt values ​​between the various resonators are increased. 2 The restriction of degrees of freedom is beneficial to improving the roll-off performance of the entire filter.

[0005] Furthermore, the main structure of the thin-film bulk acoustic resonator (FBAR) is a "sandwich" structure consisting of an electrode-piezoelectric film-electrode, that is, a piezoelectric material sandwiched between two layers of metal electrodes. By inputting a sinusoidal signal between the two electrodes, 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 back into an electrical signal output. The FBAR mainly utilizes the longitudinal piezoelectric coefficient of the piezoelectric film to generate the piezoelectric effect, so its main operating mode is the longitudinal wave mode in the thickness direction, that is, the sound waves of the bulk acoustic resonator are mainly within the thin film of the resonator, and the main vibration direction is longitudinal. However, due to the existence of boundaries, Lamb waves that are not perpendicular to the piezoelectric film layer exist at the boundaries. At this time, transverse Lamb waves will leak from the piezoelectric film layer laterally, resulting in acoustic loss and thus reducing the Q value of the resonator. There is still a need in the existing technology to further reduce transverse Lamb wave leakage. Summary of the Invention

[0006] The present invention is proposed to alleviate or solve at least one of the above-mentioned problems in the prior art.

[0007] According to one aspect of an embodiment of the present invention, a bulk acoustic resonator is provided, comprising:

[0008] Base;

[0009] Acoustic mirror;

[0010] Bottom electrode;

[0011] piezoelectric layer; and

[0012] Top electrode,

[0013] in:

[0014] The overlapping area of ​​the top electrode, piezoelectric layer, and bottom electrode in the thickness direction of the resonator constitutes the effective region of the resonator;

[0015] The piezoelectric layer includes a first layer and a second layer, with an acoustic resistive layer disposed between the first layer and the second layer. The second layer is above the first layer, and the inner edge of the acoustic resistive layer is located inside the boundary of the acoustic mirror in the horizontal direction. The acoustic resistive layer is different from the acoustic resistive layer.

[0016] The resonator also includes a channel or opening that connects the acoustic resist layer to the outside.

[0017] Embodiments of the present invention also relate to a bulk acoustic wave resonator assembly, comprising at least two bulk acoustic wave resonators, wherein at least one bulk acoustic wave resonator is the resonator described above.

[0018] Embodiments of the present invention also relate to a method for manufacturing a bulk acoustic resonator.

[0019] The resonator includes a substrate, an acoustic mirror, a bottom electrode, a piezoelectric layer, and a top electrode. The piezoelectric layer includes a first layer and a second layer. A gap layer is provided between the first layer and the second layer at the non-electrode connection end of the top electrode. The method includes the following steps:

[0020] The sacrificial layer is formed and graphically represented on the first layer; and

[0021] The second layer covers the first layer and the sacrificial layer above it.

[0022] in:

[0023] The method further includes the steps of: removing the second layer by etching at the non-electrode connection end of the top electrode to expose the outer end of the sacrificial layer; and releasing the sacrificial layer to form the void layer; or

[0024] The method further includes the steps of: forming a release channel penetrating the second layer in the thickness direction of the second layer on the outside of the non-electrode connection end of the top electrode; and releasing the sacrificial layer via the release channel to form the void layer.

[0025] Embodiments of the present invention also relate to a filter, including the resonator or component described above.

[0026] Embodiments of the present invention also relate to an electronic device, including the filter described above, the resonator described above, or the component described above. Attached Figure Description

[0027] The following description and accompanying drawings will better aid in understanding these and other features and advantages of the various embodiments disclosed herein, wherein the same reference numerals in the drawings always denote the same parts, wherein:

[0028] Figure 1 This is a top view schematic diagram of a bulk acoustic resonator according to an exemplary embodiment of the present invention;

[0029] Figure 2-4 For different exemplary embodiments of the present invention, along Figure 1 A schematic diagram of the cross-section of the bulk acoustic resonator of the MOM' line in the diagram;

[0030] Figure 5 An example diagram illustrates the relationship between the width of the AW structure and the electromechanical coupling coefficient;

[0031] Figure 6 Exemplary examples show the relationship between the width of the AW structure and the parallel resonant impedance of the bulk acoustic resonator when the AW structure is disposed in the piezoelectric layer and when the AW structure is disposed between the top electrode and the piezoelectric layer.

[0032] Figure 7Examples show the relationship between the width of the AW structure and the parallel resonant impedance of the bulk acoustic wave resonator when the AW structure is disposed in the piezoelectric layer and the upper piezoelectric layer is removed, and when the AW structure is disposed in the piezoelectric layer and the upper piezoelectric layer is not removed.

[0033] Figure 8-10 For different exemplary embodiments of the present invention, along Figure 1 A schematic diagram of the cross-section of the bulk acoustic resonator of the MOM' line in the diagram;

[0034] Figure 11 This is a top view schematic diagram of a bulk acoustic resonator according to another exemplary embodiment of the present invention;

[0035] Figure 12 For an exemplary embodiment of the present invention, along Figure 11 A schematic diagram of the cross-section of the bulk acoustic resonator of the MOM' line in the diagram;

[0036] Figure 13 This is a top view schematic diagram of a bulk acoustic resonator according to another exemplary embodiment of the present invention;

[0037] Figure 14 A top view schematic diagram of a bulk acoustic resonator according to another exemplary embodiment of the present invention;

[0038] Figure 15 For an exemplary embodiment of the present invention, along Figure 14 A schematic diagram of the cross-section of the bulk acoustic resonator of the MOM' line in the diagram;

[0039] Figure 16A-16G An example is shown Figure 15 A cross-sectional schematic diagram of the fabrication process of a bulk acoustic resonator;

[0040] Figure 17 This is a schematic cross-sectional view illustrating, for example, that the acoustic resist layer is disposed in the middle of the piezoelectric layer and the upper piezoelectric layer is not removed. Detailed Implementation

[0041] The technical solution of the present invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings. In this specification, 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 accompanying drawings is intended to explain the overall inventive concept of the present invention and should not be construed as a limitation thereof. These are only some embodiments of the invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0042] First, the reference numerals in the accompanying drawings of this invention are explained as follows:

[0043] 10: Substrate, with optional materials including single-crystal silicon, gallium nitride, gallium arsenide, sapphire, quartz, silicon carbide, diamond, etc.

[0044] 20: Acoustic mirror, which can be a cavity, or it can be a Bragg reflector layer or other equivalent forms. In the embodiments of the present invention, a cavity form is used.

[0045] 20A: Release channel, connecting the release port 90 to the acoustic mirror cavity.

[0046] 21: Sacrificial layer, which is placed in the cavity during the fabrication of the resonator when the acoustic mirror is in the form of a cavity, and is released in the subsequent process to form the acoustic mirror cavity. The sacrificial layer 21 can be made of materials such as silicon dioxide, doped silicon dioxide, polycrystalline silicon, or amorphous silicon.

[0047] 30: Bottom electrode (including bottom electrode pins), the material can be molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or a composite or alloy of the above metals, etc.

[0048] 41: The first piezoelectric layer can be a single-crystal piezoelectric material, such as single-crystal aluminum nitride, single-crystal gallium nitride, single-crystal lithium niobate, single-crystal lead zirconate titanate (PZT), single-crystal potassium niobate, single-crystal quartz film, or single-crystal lithium tantalate, etc. It can also be a polycrystalline piezoelectric material (as opposed to single-crystal, a non-single-crystal material), such as polycrystalline aluminum nitride, zinc oxide, PZT, etc. It can also be a rare earth element doped with a certain atomic ratio of the above materials. Mixed materials, such as doped aluminum nitride, contain 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 (Tm), ytterbium (Yb), lutetium (Lu), etc.

[0049] 42: The second piezoelectric layer can be made of a single-crystal piezoelectric material, such as single-crystal aluminum nitride, single-crystal gallium nitride, single-crystal lithium niobate, single-crystal lead zirconate titanate (PZT), single-crystal potassium niobate, single-crystal quartz film, or single-crystal lithium tantalate, etc. It can also be made of a polycrystalline piezoelectric material (as opposed to single-crystal, a non-single-crystal material), such as polycrystalline aluminum nitride, zinc oxide, PZT, etc. It can also be a rare earth element containing a certain atomic ratio of the above materials. The doped material can be, for example, doped aluminum nitride, which 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 (Tm), ytterbium (Yb), lutetium (Lu), etc.

[0050] 50: Top electrode (including top electrode pin), the material can be molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or a composite or alloy of the above metals, etc.

[0051] 70: Passivation layer or process layer, which can be aluminum nitride, silicon nitride or silicon dioxide, etc.

[0052] 80: Acoustic resistive layer, whose acoustic resistivity differs from that of the first piezoelectric layer 41 and the second piezoelectric layer 42, is in the form of an air gap (i.e., AW) in the illustrated embodiment of the present invention, but may also be in the form of a solid dielectric layer, such as silicon dioxide or its dopants, or silicon nitride or its dopants. As will be understood, the acoustic resistive layer may also have a greater acoustic resistivity than that of the first piezoelectric layer and the second piezoelectric layer.

[0053] 81: Sacrificial layer, which is set at the position corresponding to the air gap during the fabrication of the resonator and is released in subsequent processes to form the air gap. The sacrificial layer 81 can be made of materials such as silicon dioxide, doped silicon dioxide, polycrystalline silicon, or amorphous silicon.

[0054] 90: Release hole, used to release the sacrificial layer material inside the acoustic mirror cavity.

[0055] 91: Release channel, used to release sacrificial layer material within the void layer.

[0056] Figure 1 This is a top view schematic diagram of a bulk acoustic resonator according to an exemplary embodiment of the present invention. Figure 2 For an exemplary embodiment of the present invention, along Figure 1 A schematic diagram of the cross-section of the bulk acoustic resonator of the MOM' line.

[0057] exist Figure 1-2The bulk acoustic resonator includes a substrate 10, an acoustic mirror cavity 20 disposed in the substrate 10, a bottom electrode 30, a top electrode 50, and a piezoelectric layer, which includes a first piezoelectric layer 41 and a second piezoelectric layer 42. An acoustic resistive layer 80, in the form of an air gap, is disposed between the first and second piezoelectric layers. A passivation layer 70 is also shown in Figure 1-2.

[0058] Figure 7 Examples are shown respectively in the case where the AW structure is disposed in the piezoelectric layer and the upper piezoelectric layer is removed (in Figure 7 In the middle, corresponding to the solid line, see, for example, the embodiment. Figure 2-4 (8-10) and when the AW is set in the piezoelectric layer and the upper piezoelectric layer is not removed (in Figure 7 In the middle, corresponding to the dashed line, see, for example, the embodiment. Figure 17 The diagram shows the relationship between the width of the AW structure and the parallel resonant impedance of the bulk acoustic resonator.

[0059] Depend on Figure 7 It can be seen that, in most cases, the resonator with the AW structure placed between two piezoelectric layers and the second piezoelectric layer 42 etched or removed along the boundary of the non-electrode connection end of the top electrode has significantly better performance than the device with the second piezoelectric layer not etched or removed under the same conditions.

[0060] exist Figure 2 In this configuration, the portion of the first piezoelectric layer 41 located outside the AW structure 80 is not etched. Specifically, at the non-electrode connection end of the top electrode, the thickness of the portion of the first layer located outside the outer edge of the acoustic resist layer is equal to the thickness of the portion located inside the outer edge of the acoustic resist layer. Corresponding to... Figure 2 In the structure shown, the second piezoelectric layer 42 is etched along with the top electrode during etching, so that the second piezoelectric layer 42, the top electrode, and the passivation layer form the same etch surface. The first piezoelectric layer 41 beneath the AW structure 80 is not etched in the non-effective region of the resonator, but the second piezoelectric layer 42 is etched. Therefore, at the non-electrode connection end of the top electrode of the resonator, there is no second piezoelectric layer in the non-effective region. In this case, the AW structure 80, the second piezoelectric layer 41, the non-electrode connection end of the top electrode, and the passivation layer 70 form the same etch surface at the non-electrode connection end. It should be noted that the end faces of the passivation layer 70 and the non-electrode connection end of the top electrode are not required to be flush.

[0061] Figure 3 For an exemplary embodiment of the present invention, similar to along Figure 1 A schematic diagram of the cross-section of the bulk acoustic resonator of the MOM' line. Figure 3 and Figure 2 The difference is that, in Figure 3In the middle, the portion of the first piezoelectric layer 41 on the outer side of the AW structure 80 is partially etched, while... Figure 2 In this process, the corresponding portion of the first piezoelectric layer 41 is not etched. That is, in Figure 3 In the process, at the non-electrode connection end of the top electrode, the thickness of the portion of the first layer located outside the outer edge of the acoustic resist layer is less than the thickness of the portion located inside the outer edge of the acoustic resist layer. In the actual fabrication process, during the etching of the second piezoelectric layer 42, a certain amount of over-etching is required. Furthermore, because the etching materials of the first piezoelectric layer 41 and the second piezoelectric layer 42 are relatively small or have the same etching rate due to being the same material, the etching of the second piezoelectric layer 42 may cause some etching of the first piezoelectric layer 41, resulting in... Figure 3 The structure shown is shown in this case. In this case, the first piezoelectric layer 41 is partially etched.

[0062] Figure 4 For an exemplary embodiment of the present invention, similar to along Figure 1 A schematic diagram of the cross-section of the bulk acoustic resonator of the MOM' line. Figure 4 and Figure 2 The difference is that, in Figure 4 In the middle, the portion of the first piezoelectric layer 41 located outside the AW structure 80 was etched away, while... Figure 2 In this process, the corresponding portion of the first piezoelectric layer was not etched. That is, in... Figure 4 In the process, at the non-electrode connection end of the top electrode, the portion of the first layer located outside the outer edge of the acoustic resist layer is removed. That is, during the etching of the second piezoelectric layer 42, the first piezoelectric layer 41 can be etched away together, thereby obtaining... Figure 4 The structure.

[0063] exist Figure 2-4 In the process of etching or removal, the end face of the second piezoelectric layer 42 is a vertical end face and is flush with the end face of the non-electrode connection end of the top electrode, but the present invention is not limited thereto.

[0064] Figure 8-10 For different exemplary embodiments of the present invention, along Figure 1 A schematic diagram of the cross-section of the bulk acoustic resonator of the MOM' line. Figure 8 In this configuration, although the end face of the second piezoelectric layer 42 is still a vertical end face, the end face of the non-electrode connection end of the top electrode is located outside the end face of the second piezoelectric layer 42 in the horizontal direction, and there is a distance Δd between the two end faces in the horizontal direction. Figure 9 In this configuration, although the end face of the second piezoelectric layer 42 is still a vertical end face, the end face of the non-electrode connection end of the top electrode is located inside the end face of the second piezoelectric layer 42 in the horizontal direction, and there is a distance Δd between the two end faces in the horizontal direction. Figure 10In the middle, the end face of the second piezoelectric layer 42 is an outward inclined surface, and the end face of the non-electrode connection end of the top electrode is located inside the end face of the second piezoelectric layer 42 in the horizontal direction, and there is a distance Δd between the two end faces in the horizontal direction. Figure 10 In this embodiment, the slope angle of the second piezoelectric layer 42 is α. In this embodiment, Δd is between 0.25 and 5 μm. As those skilled in the art will understand, the aforementioned outward-sloping slope can also be an inward-sloping slope. In this embodiment, the slope angle α is in the range of 10-80 degrees.

[0065] exist Figure 2-4 In embodiments 8-10, a portion of the second piezoelectric layer 42 is removed (e.g., by etching) at the non-electrode connection end of the top electrode, thereby directly exposing the AW structure, acoustic damping layer, or air gap. Thus, the air-reflecting surface formed after the cutting can prevent energy or lateral Lamb waves from leaking through the second piezoelectric layer outside the AW structure, such as... Figure 7 As shown, this improves the resonator's performance. More specifically, because an air reflector (impedance mismatch interface) is formed at the non-electrode connection point corresponding to the second piezoelectric layer 42, the transverse Lamb wave is strongly reflected at this air reflector, thereby reducing transverse Lamb wave leakage and improving the resonator's Q value. If only the AW structure is set without etching the second piezoelectric layer 42, then the second piezoelectric layer 42 is a continuous interface, and the transverse Lamb wave can leak out of the effective region through the second piezoelectric layer 42, thereby reducing the resonator's Q value.

[0066] Furthermore, when the etched interface of the second piezoelectric layer 42 and the end face of the non-electrode connection of the top electrode are not on the same interface, they can reflect more transverse Lamb waves compared to when they are on the same interface. Figure 8 For example, the second piezoelectric layer 42 can effectively reflect transverse waves with a wavelength of 1 / 4 L1, while the top electrode can effectively reflect transverse waves with a wavelength of 1 / 4 L1+Δd. However, when the etched interface of the second piezoelectric layer 42 is flush with the end face of the non-electrode connection of the top electrode, this structure will only effectively reflect transverse waves with a wavelength of 1 / 4 L1. Additionally, as... Figure 10 As shown, when the end face of the second piezoelectric layer 42 is inclined, the second piezoelectric layer has two distances: L2 is the distance from the inner edge of the AW structure to the outer edge of the upper surface, and L3 is the distance from the inner edge of the AW structure to the outer edge of the lower surface. Therefore, the second piezoelectric layer 42 can effectively reflect transverse waves with a wavelength between L2 and L3, which is 1 / 4 of the transverse wavelength. Thus, it can reflect more waves, and therefore the Q value will be higher.

[0067] exist Figure 2-4In the embodiments shown in 8-10, the second piezoelectric layer 42 is removed at the non-electrode connection end of the top electrode to expose the AW structure, acoustic barrier layer, or air gap, but the present invention is not limited thereto.

[0068] Figure 11 This is a top view schematic diagram of a bulk acoustic resonator according to another exemplary embodiment of the present invention. Figure 12 For an exemplary embodiment of the present invention, along Figure 11 A schematic diagram of the cross-section of the bulk acoustic resonator of the MOM' line. Figure 11-12 In the middle, the second piezoelectric layer 42 has a channel 91 on the outside of the non-electrode connection end of the top electrode, which communicates with the AW structure or the void layer 80.

[0069] like Figure 11 As shown, the void layer 80 is continuously disposed along the circumferential direction of the effective area at least at the non-electrode connection end of the top electrode, and correspondingly, the channel 91 is a continuous channel disposed along the circumferential direction of the effective area.

[0070] By setting channel 91, the sacrificial layer material within the void layer 80 can be released to form a void layer. In this case, channel 91 serves as a release channel. Furthermore, the second piezoelectric layer 42 can be cut off or partially cut off at the non-electrode connection end of the top electrode, which can also prevent or reduce energy leakage during resonator operation. The effect of preventing or reducing energy leakage can be seen, for example, in [reference needed]. Figure 7 .

[0071] Channel 91 can also serve only to prevent or reduce energy leakage during the operation of the resonator. In this case, the acoustic resist layer 80 is not in the form of a void layer, but rather in the form of a solid dielectric layer.

[0072] exist Figure 2-4 As shown in Figures 8-12, the acoustic barrier layer 80 is arranged in a continuous manner, but the present invention is not limited thereto. Figure 13 This is a top view schematic diagram of a bulk acoustic resonator according to another exemplary embodiment of the present invention, along... Figure 13 The cross-sectional view obtained by the MOM' line in the diagram is similar to Figure 12 .exist Figure 13 As can be seen, the acoustic resistive layer 80 includes multiple acoustic resistive sections, which are spaced apart in the circumferential direction along the effective region of the resonator. Correspondingly, the channel 91 can be a plurality of holes communicating with the plurality of acoustic resistive sections (corresponding to the case of partial cut-off processing), or it can be a continuous channel arranged in the circumferential direction of the effective region and communicating with each acoustic resistive section (corresponding to the case of cut-off).

[0073] Figure 6Exemplary examples show the relationship between the width of the AW structure and the parallel resonant impedance of the bulk acoustic wave resonator when the AW structure is disposed within the piezoelectric layer and when the AW structure is disposed between the top electrode and the piezoelectric layer. Figure 6 In the diagram, the horizontal axis represents the width of the AW structure (in μm), and the vertical axis represents the parallel resonant impedance Rp of the resonator (in ohms). Figure 6 In the diagram, the dashed line indicates the AW structure is positioned between the top electrode and the piezoelectric layer, while the solid line indicates the AW structure is positioned within the piezoelectric layer. For example... Figure 6 As shown, the parallel resonant impedance of the AW structure within the piezoelectric layer is significantly higher than that of the AW structure between the piezoelectric layer and the top electrode. Therefore, by placing an acoustic resistive layer 80 between the first piezoelectric layer 41 and the second piezoelectric layer 42, the performance of the resonator can be effectively improved compared to placing the acoustic resistive layer between the top electrode and the piezoelectric layer.

[0074] By providing an acoustic impedance layer 80 between the first piezoelectric layer 41 and the second piezoelectric layer 42, the electromechanical coupling coefficient of the resonator can also be adjusted. Since the first piezoelectric layer 41 and the second piezoelectric layer 42 are fabricated separately, these two piezoelectric layers can be made of different materials, thus allowing for free adjustment of the resonator's electromechanical coupling coefficient. For example, the first piezoelectric layer 41 may be a piezoelectric layer of a certain material (e.g., a piezoelectric layer of aluminum nitride, zinc oxide, lead zirconate titanate, lithium niobate, quartz, potassium niobate, or lithium tantalate), while the second piezoelectric layer 42 may be a doped layer of the same material as the first piezoelectric layer 41, doped with at least one of the rare earth elements mentioned above. In a specific embodiment, both the first piezoelectric layer 41 and the second piezoelectric layer 42 are based on aluminum nitride piezoelectric materials, but one layer is an undoped piezoelectric material, and the other layer is a scandium-doped piezoelectric material. For example, both the first and second piezoelectric layers are doped layers of the same material, only the doping concentration of the first piezoelectric layer differs from that of the second piezoelectric layer. In one specific embodiment, both the first piezoelectric layer 41 and the second piezoelectric layer 42 are based on aluminum nitride piezoelectric materials doped with the rare earth element scandium, only the doping concentrations of the first and second piezoelectric layers differ. Another example is that the material of the first piezoelectric layer 41 is one of aluminum nitride, zinc oxide, lead zirconate titanate, lithium niobate, quartz, potassium niobate, and lithium tantalate, while the material of the second piezoelectric layer 42 is a material different from that of the first piezoelectric layer, among aluminum nitride, zinc oxide, lead zirconate titanate, lithium niobate, quartz, potassium niobate, and lithium tantalate. In one specific embodiment, the first piezoelectric layer is aluminum nitride, and the second piezoelectric layer is zinc oxide.

[0075] Therefore, in this invention, while improving the resonator performance by setting an AW structure in the piezoelectric layer, different piezoelectric layers can be prepared on the upper and lower sides of the AW structure to achieve free setting of the electromechanical coupling coefficient of the resonator.

[0076] The use of piezoelectric layers 41 and 42 with different doping can significantly adjust the electromechanical coupling coefficient of the resonator. For example, when fabricating a duplexer within the same die, a large difference (greater than 1%) in the electromechanical coupling coefficient of the resonator in the transmit filter Tx and the receive filter Rx is required. However, within either the transmit filter Tx or the receive filter Rx, a smaller difference (less than 1%) in the electromechanical coupling coefficients between different resonators is needed. In this case, the width of the AW structure within the effective region of the resonator can be adjusted, i.e., by adjusting... Figure 2 The width L1 of the AW structure in the filter is used to adjust the electromechanical coupling coefficient of the resonator inside the filter. For example... Figure 2 As shown, L1 is the width of the AW structure at the non-electrode connection end of the top electrode, which is the horizontal distance between the non-electrode connection end of the top electrode and the inner edge of the AW structure.

[0077] The acoustic resist layer can also be further disposed at the electrode connection end of the top electrode. Figure 14-15 Such an embodiment is shown. Figure 14 This is a top view schematic diagram of a bulk acoustic resonator according to another exemplary embodiment of the present invention. Figure 15 For an exemplary embodiment of the present invention, along Figure 14 A schematic diagram of the cross-section of the bulk acoustic resonator with the MOM' line. At this point, the width of the AW structure within the effective region of the resonator can be adjusted, that is, by adjusting... Figure 15 The widths L1 and L2 of the AW structure in the filter are used to adjust the electromechanical coupling coefficient of the resonator inside the filter. For example... Figure 15 As shown, L1 is the width of the AW structure at the non-electrode connection end of the top electrode, which is the horizontal distance between the non-electrode connection end of the top electrode and the inner edge of the AW structure; as Figure 15 As shown, L2 is the width of the AW structure at the electrode connection end of the top electrode, and it is the horizontal distance between the acoustic mirror boundary and the inner edge of the AW structure at the connection end of the top electrode.

[0078] Figure 5 An exemplary diagram illustrates the relationship between the width of the AW structure or air gap and the electromechanical coupling coefficient. In Figure 5 In the figure, the horizontal axis represents the width of the AW structure (in μm), and the vertical axis represents the electromechanical coupling coefficient. Figure 5 This indicates the effect of the width of the AW structure of the resonator on the electromechanical coupling coefficient when the width of the AW structure on each side of the effective region of the resonator is the same. Figure 5 As shown, the electromechanical coupling coefficient gradually decreases with the increase of the AW width. Therefore, the electromechanical coupling coefficient of the resonator can be adjusted by regulating the width of the AW structure.

[0079] For a resonator whose effective region is a polygon, the width of the AW structure on each side can be the same or different.

[0080] The AW structure, acoustic barrier layer, or air gap can be placed only at the non-electrode connection end of the top electrode, as shown in Figures 2-4 and 8-13; or it can be placed simultaneously at both the non-electrode connection end and the electrode connection end of the top electrode, such as... Figure 14-15 As shown.

[0081] In this invention, see, for example, [see...] Figure 2-4 As shown in Figures 8-13, the AW structure, acoustic barrier layer, or air gap is disposed at the non-electrode connection end of the top electrode. When the effective area of ​​the resonator is a polygon, it may include the case where it is disposed on only one or more sides of the non-electrode connection end, or it may include the case where it is disposed on all sides of the non-electrode connection end.

[0082] In this invention, see, for example, [see...] Figure 14-15 An AW structure, acoustic resist layer, or air gap is provided at the electrode connection end of the top electrode. When the effective area of ​​the resonator is a polygon, it means that an AW structure, acoustic resist layer, or air gap is provided on the side where the electrode connection end of the top electrode is located.

[0083] An AW structure, acoustic barrier layer, or air gap can also be set around the entire effective area of ​​the resonator.

[0084] When the thickness of the piezoelectric layer is constant, and the same piezoelectric material is used on both the top and bottom sides of the AW structure, the electromechanical coupling coefficient of the resonator is a fixed value under the same conditions, regardless of the location of the AW structure within the piezoelectric layer. However, using different piezoelectric layer materials on the top and bottom sides of the AW structure increases the design freedom of the resonator's electromechanical coupling coefficient. For example, the first piezoelectric layer 41 uses undoped aluminum nitride, and the second piezoelectric layer 42 uses scandium-doped aluminum nitride. When the piezoelectric layer thickness is fixed, the electromechanical coupling coefficient is 6% when only undoped aluminum nitride is used, and 10% when only doped aluminum nitride is used. Therefore, with a constant piezoelectric layer thickness, the electromechanical coupling coefficient of the resonator can be freely varied between 6% and 10% by controlling the doping concentration of the first piezoelectric layer 41 and the second piezoelectric layer 42. Once the thicknesses of the two piezoelectric layers are determined, the electromechanical coupling coefficients of different resonators within the filter can be fine-tuned by controlling the change in the width of the AW structure. Therefore, this scheme can maximize the design freedom of the electromechanical coupling coefficients of the resonators within the filter.

[0085] exist Figure 2In this design, the materials of the first piezoelectric layer 41 and the second piezoelectric layer 42 can be different. When the thicknesses of the first piezoelectric layer 41 and the second piezoelectric layer 42 are fixed, for a certain electromechanical coupling coefficient of the resonator, the required electromechanical coupling coefficient can be achieved by changing the materials of the piezoelectric layers. After the doping or materials of the first piezoelectric layer 41 and the second piezoelectric layer 42 are determined, the desired electromechanical coupling coefficient can be achieved by changing... Figure 2 The width L1 in the figure further adjusts the electromechanical coupling coefficient of the resonator.

[0086] exist Figure 15 In this design, the materials of the first piezoelectric layer 41 and the second piezoelectric layer 42 can be different. When the thicknesses of the first piezoelectric layer 41 and the second piezoelectric layer 42 are fixed, for a certain electromechanical coupling coefficient of the resonator, the required electromechanical coupling coefficient can be achieved by changing the materials of the piezoelectric layers. After the doping or materials of the first piezoelectric layer 41 and the second piezoelectric layer 42 are determined, the desired electromechanical coupling coefficient can be achieved by changing... Figure 15 The widths L1 and L2 in the diagram are used to further adjust the electromechanical coupling coefficient of the resonator.

[0087] Figure 2 The diagram also shows the thicknesses of the first piezoelectric layer 41 and the second piezoelectric layer 42, which are H1 and H2, respectively. The proportions of the two different piezoelectric materials can be adjusted by regulating the ratio of H1 to H2, thereby adjusting the electromechanical coupling coefficient of the resonator. Similarly, once H2 and H1 are determined, the electromechanical coupling coefficient can be adjusted by changing... Figure 2 The widths L1 and L2 in the diagram are used to further adjust the electromechanical coupling coefficient of the resonator.

[0088] like Figure 2 As shown, the position of the AW structure sandwiched between the first piezoelectric layer 41 and the second piezoelectric layer 42 is not fixed. In one embodiment of the invention, the distance between the lower surface of the AW structure and the lower surface of the first piezoelectric layer 41 is greater than... The distance between the upper surface of the AW structure and the second piezoelectric layer 42 is also greater than... The thickness range of the AW structure is

[0089] The following reference Figure 16A-16G Exemplary Description Figure 14-15 The fabrication process of a bulk acoustic resonator. It should be noted that this fabrication process can also be used when only an acoustic resistive layer is provided at the non-electrode connection end of the top electrode. In this case, unlike the steps below, a sacrificial layer corresponding to the acoustic resistive layer and the release of the sacrificial layer are no longer provided.

[0090] First, such as Figure 16AAs shown, a cavity serving as an acoustic mirror 20 is formed on the upper surface of the substrate 10. Then, a sacrificial material is placed on the upper surface of the substrate 10 to fill the cavity. Then, the sacrificial material on the upper surface of the substrate 10 is removed by a CMP (chemical mechanical polishing) process, and the upper surface of the sacrificial material in the cavity is flush with the upper surface of the substrate 10 to form a sacrificial layer 21.

[0091] Second, such as Figure 16B As shown, in Figure 16A The electrode material layer is deposited and patterned on the structure to form the bottom electrode 30.

[0092] Third, such as Figure 16C As shown, in Figure 16B A first piezoelectric layer 41 is deposited on the structure, which may be, for example, an undoped piezoelectric layer.

[0093] Fourth, such as Figure 16D As shown, in Figure 16C A sacrificial material is deposited and patterned on the upper surface of the first piezoelectric layer 41 to form a sacrificial layer 81. This sacrificial layer 81 will be released later to form the AW structure 80. Figure 16D As shown, a sacrificial layer 81 is provided for the electrode connection end and non-connection end of the top electrode.

[0094] Fifth, such as Figure 16E As shown, in Figure 16D A second piezoelectric layer 42 is deposited on the upper surface of the structure, which may be, for example, a doped piezoelectric layer.

[0095] Sixth, such as Figure 16F As shown, in Figure 16E A top electrode 50 and a protective layer or passivation layer 70 are prepared on the upper surface of the structure.

[0096] Seventh, at the non-electrode connection end of the top electrode, the passivation layer 70, the top electrode 50, and the second piezoelectric layer 42 are etched to expose the sacrificial layer 81 at the non-electrode connection end of the top electrode.

[0097] Eighth, release sacrificial layer 21 and sacrificial layer 81 to form acoustic mirror 20 and AW structure 80 respectively, as shown. Figure 16G As shown.

[0098] It should be noted that the above methods and steps are merely exemplary, and those skilled in the art can adjust and modify them. For example, the second piezoelectric layer can be prepared and etched first, followed by the preparation of the top electrode and passivation layer.

[0099] It should be noted that, in this invention, each numerical range, except where explicitly stated not to include endpoint values, can be either an endpoint value or the median of each numerical range, and all of these are within the protection scope of this invention.

[0100] In this invention, "upper" and "lower" are relative to the bottom surface of the base. For a component, the side closer to the bottom surface is the lower side, and the side farther from the bottom surface is the upper side.

[0101] In this invention, "inner" and "outer" refer to the center of the effective region of the resonator (the overlapping area of ​​the piezoelectric layer, top electrode, bottom electrode, and acoustic mirror in the thickness direction of the resonator constitutes the effective region) in the lateral or radial direction. A side or end of a component closer to the center of the effective region is called the inner side or inner end, while a side or end of the component farther from the center of the effective region is called the outer side or outer end. For a reference position, being inside the position means being between that position and the center of the effective region in the lateral or radial direction, while being outside the position means being farther from the center of the effective region in the lateral or radial direction than that position.

[0102] As will be understood by those skilled in the art, bulk acoustic resonators can be used to form filters or other semiconductor devices.

[0103] Based on the above, the present invention proposes the following technical solution:

[0104] 1. A bulk acoustic resonator, comprising:

[0105] Base;

[0106] Acoustic mirror;

[0107] Bottom electrode;

[0108] piezoelectric layer; and

[0109] Top electrode,

[0110] in:

[0111] The overlapping area of ​​the top electrode, piezoelectric layer, and bottom electrode in the thickness direction of the resonator constitutes the effective region of the resonator;

[0112] The piezoelectric layer includes a first layer and a second layer, with an acoustic resistive layer disposed between the first layer and the second layer. The second layer is above the first layer, and the inner edge of the acoustic resistive layer is located inside the boundary of the acoustic mirror in the horizontal direction. The acoustic resistive layer is different from the acoustic resistive layer.

[0113] The resonator also includes a channel or opening that connects the acoustic resist layer to the outside.

[0114] 2. The resonator according to 1, wherein:

[0115] At the non-electrode connection end of the top electrode, the outer edge of the acoustic resist layer is flush with the end of the second layer, and the outer edge of the acoustic resist layer forms or is located within the opening; or

[0116] Based on the acoustic impedance layer, the non-electrode connection end of the top electrode forms a cantilever structure.

[0117] 3. The resonator according to 2, wherein:

[0118] At the non-electrode connection end of the top electrode, the end face of the second layer is a vertical surface or an inclined surface.

[0119] 4. The resonator according to 2, wherein:

[0120] At the non-electrode connection end of the top electrode, the thickness of the portion of the first layer located outside the outer edge of the acoustic resist layer is equal to the thickness of the portion located inside the outer edge of the acoustic resist layer; or

[0121] At the non-electrode connection end of the top electrode, the thickness of the portion of the first layer located outside the outer edge of the acoustic resist layer is less than the thickness of the portion located inside the outer edge of the acoustic resist layer; or

[0122] At the non-electrode connection end of the top electrode, the portion of the first layer located outside the outer edge of the acoustic resist layer is removed.

[0123] 5. The resonator according to 2, wherein:

[0124] The non-electrode connection end of the top electrode is offset from the end of the second layer in the horizontal direction.

[0125] 6. The resonator according to claim 1, wherein:

[0126] The acoustic resistive layer includes multiple acoustic resistive sections, which are spaced apart in the circumferential direction along the effective region of the resonator. The outer edges of the multiple acoustic resistive sections form multiple openings spaced apart in the circumferential direction along the effective region; or

[0127] The acoustic resisting layer is continuously arranged in the circumferential direction along the effective region of the resonator, and the outer edge of the acoustic resisting layer forms the opening continuously arranged in the circumferential direction along the effective region.

[0128] 7. The resonator according to any one of 2-6, wherein:

[0129] The acoustic resistive layer is a void layer or a solid dielectric layer.

[0130] 8. The resonator according to claim 1, wherein:

[0131] At the non-electrode connection end of the top electrode, the channel passes through the second layer in the thickness direction of the second layer, and the channel is located outside the non-electrode connection end of the top electrode in the horizontal direction. The channel is connected to or communicates with the acoustic resistive layer.

[0132] 9. The resonator according to 8, wherein:

[0133] The acoustic resist layer is continuously disposed at least at the non-electrode connection end of the top electrode along the circumferential direction of the effective region, and the channel is a continuous channel disposed along the circumferential direction of the effective region and communicating with or connected to the acoustic resist layer, or the channel includes a plurality of holes spaced apart along the circumferential direction of the effective region; or

[0134] The acoustic resistive layer includes multiple acoustic resistive sections, which are spaced apart in the circumferential direction along the effective region of the resonator. The channel includes multiple holes that communicate with or connect to the multiple acoustic resistive sections, or the channel is a continuous channel arranged circumferentially along the effective region and communicating with or connecting to the multiple acoustic resistive sections.

[0135] 10. The resonator according to 8 or 9, wherein:

[0136] The acoustic barrier layer is a void layer, and the channel is a release channel communicating with the void layer.

[0137] 11. The resonator according to any one of 1-10, wherein:

[0138] The piezoelectric material in the first layer is different from the piezoelectric material in the second layer.

[0139] 12. The resonator according to 11, wherein:

[0140] One of the first and second layers is a doped layer of the other; or

[0141] Both the first and second layers are doped layers of the same material, but the doping concentration of the first layer differs from that of the second layer; or

[0142] The first layer is made of one of the following materials: aluminum nitride, zinc oxide, lead zirconate titanate, lithium niobate, quartz, potassium niobate, and lithium tantalate. The second layer is made of a different material from the first layer among aluminum nitride, zinc oxide, lead zirconate titanate, lithium niobate, quartz, potassium niobate, and lithium tantalate.

[0143] 13. The resonator according to any one of 1-12, wherein:

[0144] The acoustic resistive layer includes a non-connection end acoustic resistive layer at the non-electrode connection end of the top electrode, and the inner edge of the non-connection end acoustic resistive layer is located inside the non-electrode connection end of the top electrode in the horizontal direction.

[0145] 14. The resonator according to 13, wherein:

[0146] The non-electrode connection end of the top electrode is located inside the boundary of the acoustic mirror or flush with the boundary of the acoustic mirror in the horizontal direction;

[0147] In the horizontal direction, there is a first distance between the non-electrode connection end of the top electrode and the inner edge of the acoustic resist layer of the non-connection end, the first distance being in the range of 0.25-10μm.

[0148] 15. The resonator according to 13, wherein:

[0149] The acoustic resistive layer also includes a connection end acoustic resistive layer at the electrode connection end of the top electrode.

[0150] 16. The resonator according to 15, wherein:

[0151] In the horizontal direction, there is a second distance between the boundary of the acoustic mirror and the inner edge of the acoustic resist layer at the connection end, and the second distance is in the range of 0.25-10μm.

[0152] 17. The resonator according to claim 1, wherein:

[0153] The thickness of the first layer is different from the thickness of the second layer.

[0154] 18. A bulk acoustic resonator assembly, comprising:

[0155] At least two bulk acoustic resonators, wherein at least one bulk acoustic resonator is a resonator according to any one of 1-17.

[0156] 19. The component according to 18, wherein:

[0157] The at least two bulk acoustic resonators include a first resonator and a second resonator.

[0158] Both the first resonator and the second resonator are resonators according to any one of 1-17.

[0159] 20. The component according to 19, wherein:

[0160] The first resonator and the second resonator are the resonators according to 12.

[0161] 21. The component according to 20, wherein:

[0162] The difference between the electromechanical coupling coefficient of the first resonator and the electromechanical coupling coefficient of the second resonator is in the range of 0%-10%.

[0163] 22. The component according to any one of 18-21, wherein:

[0164] Both the first and second resonators are resonators based on 14 or 16.

[0165] The widths of the acoustic resist layer of the first resonator and the corresponding acoustic resist layer of the second resonator are different.

[0166] 23. A method for manufacturing a bulk acoustic resonator, the resonator comprising a substrate, an acoustic mirror, a bottom electrode, a piezoelectric layer, and a top electrode, the piezoelectric layer comprising a first layer and a second layer, wherein a void layer is provided between the first layer and the second layer at the non-electrode connection end of the top electrode, the method comprising the steps of:

[0167] The sacrificial layer is formed and graphically represented on the first layer; and

[0168] The second layer covers the first layer and the sacrificial layer above it.

[0169] in:

[0170] The method further includes the steps of: removing the second layer at the non-electrode connection end of the top electrode by etching to expose the outer end of the sacrificial layer; and releasing the sacrificial layer to form the void layer; or

[0171] The method further includes the steps of: forming a release channel in the second layer, extending through the second layer in the thickness direction, on the outside of the non-electrode connection end of the top electrode; and releasing the sacrificial layer via the release channel to form the void layer.

[0172] 24. A filter comprising a bulk acoustic resonator according to any one of 1-17, or a bulk acoustic resonator assembly according to any one of 18-22.

[0173] 25. An electronic device comprising the filter according to claim 24, or the bulk acoustic resonator according to any one of claims 1-17, or the bulk acoustic resonator assembly according to any one of claims 18-22.

[0174] The electronic devices mentioned here include, but are not limited to, intermediate products such as radio frequency front-ends and filtering and amplification modules, as well as terminal products such as mobile phones, WIFI, and drones.

[0175] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that variations may be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A bulk acoustic resonator, comprising: Base; Acoustic mirror; Bottom electrode; piezoelectric layer; and Top electrode, in: The overlapping area of ​​the top electrode, piezoelectric layer, and bottom electrode in the thickness direction of the resonator constitutes the effective region of the resonator; The piezoelectric layer includes a first layer and a second layer, with an acoustic resistive layer disposed between the first layer and the second layer. The second layer is above the first layer, and the inner edge of the acoustic resistive layer is located inside the boundary of the acoustic mirror in the horizontal direction. The acoustic resistive layer is different from the acoustic resistive layer. The resonator also includes a channel or opening that connects the acoustic resist layer to the outside. At the non-electrode connection end of the top electrode, the outer edge of the acoustic resist layer is flush with the end of the second layer, and the outer edge of the acoustic resist layer forms or is located in the opening.

2. The resonator according to claim 1, wherein: Based on the acoustic impedance layer, the non-electrode connection end of the top electrode forms a cantilever structure.

3. The resonator according to claim 2, wherein: At the non-electrode connection end of the top electrode, the end face of the second layer is a vertical surface or an inclined surface.

4. The resonator according to claim 2, wherein: At the non-electrode connection end of the top electrode, the thickness of the portion of the first layer located outside the outer edge of the acoustic resist layer is equal to the thickness of the portion located inside the outer edge of the acoustic resist layer; or At the non-electrode connection end of the top electrode, the thickness of the portion of the first layer located outside the outer edge of the acoustic resist layer is less than the thickness of the portion located inside the outer edge of the acoustic resist layer; or At the non-electrode connection end of the top electrode, the portion of the first layer located outside the outer edge of the acoustic resist layer is removed.

5. The resonator according to claim 2, wherein: The non-electrode connection end of the top electrode is offset from the end of the second layer in the horizontal direction.

6. The resonator according to claim 1, wherein: The acoustic resistive layer includes a plurality of acoustic resistive sections, which are spaced apart in the circumferential direction along the effective region of the resonator. The outer edges of the plurality of acoustic resistive sections form a plurality of openings spaced apart in the circumferential direction along the effective region. or The acoustic resisting layer is continuously arranged in the circumferential direction along the effective region of the resonator, and the outer edge of the acoustic resisting layer forms the opening continuously arranged in the circumferential direction along the effective region.

7. The resonator according to any one of claims 2-6, wherein: The acoustic resistive layer is a void layer or a solid dielectric layer.

8. The resonator according to claim 1, wherein: At the non-electrode connection end of the top electrode, the channel passes through the second layer in the thickness direction of the second layer, and the channel is located outside the non-electrode connection end of the top electrode in the horizontal direction. The channel is connected to or communicates with the acoustic resistive layer.

9. The resonator according to claim 8, wherein: The acoustic resist layer is continuously disposed at least at the non-electrode connection end of the top electrode along the circumferential direction of the effective region, and the channel is a continuous channel disposed along the circumferential direction of the effective region and communicating with or connected to the acoustic resist layer, or the channel includes a plurality of holes spaced apart along the circumferential direction of the effective region; or The acoustic resistive layer includes multiple acoustic resistive sections, which are spaced apart in the circumferential direction along the effective region of the resonator. The channel includes multiple holes that communicate with or connect to the multiple acoustic resistive sections, or the channel is a continuous channel arranged circumferentially along the effective region and communicating with or connecting to the multiple acoustic resistive sections.

10. The resonator according to claim 8 or 9, wherein: The acoustic barrier layer is a void layer, and the channel is a release channel communicating with the void layer.

11. The resonator according to any one of claims 1-6, 8, and 9, wherein: The piezoelectric material in the first layer is different from the piezoelectric material in the second layer.

12. The resonator according to claim 11, wherein: One of the first and second layers is a doped layer of the other; or Both the first and second layers are doped layers of the same material, but the doping concentration of the first layer differs from that of the second layer; or The first layer is made of one of the following materials: aluminum nitride, zinc oxide, lead zirconate titanate, lithium niobate, quartz, potassium niobate, and lithium tantalate. The second layer is made of a different material from the first layer among aluminum nitride, zinc oxide, lead zirconate titanate, lithium niobate, quartz, potassium niobate, and lithium tantalate.

13. The resonator according to any one of claims 1-6, 8, 9, and 12, wherein: The acoustic resistive layer includes a non-connection end acoustic resistive layer at the non-electrode connection end of the top electrode, and the inner edge of the non-connection end acoustic resistive layer is located inside the non-electrode connection end of the top electrode in the horizontal direction.

14. The resonator according to claim 13, wherein: The non-electrode connection end of the top electrode is located inside the boundary of the acoustic mirror or flush with the boundary of the acoustic mirror in the horizontal direction; In the horizontal direction, there is a first distance between the non-electrode connection end of the top electrode and the inner edge of the acoustic resist layer of the non-connection end, the first distance being in the range of 0.25-10μm.

15. The resonator according to claim 13, wherein: The acoustic resistive layer also includes a connection end acoustic resistive layer at the electrode connection end of the top electrode.

16. The resonator according to claim 15, wherein: In the horizontal direction, there is a second distance between the boundary of the acoustic mirror and the inner edge of the acoustic resist layer at the connection end, and the second distance is in the range of 0.25-10μm.

17. The resonator according to claim 1, wherein: The thickness of the first layer is different from the thickness of the second layer.

18. A bulk acoustic resonator assembly, comprising: At least two bulk acoustic resonators, wherein at least one bulk acoustic resonator is a resonator according to any one of claims 1-17.

19. The component of claim 18, wherein: The at least two bulk acoustic resonators include a first resonator and a second resonator. Both the first resonator and the second resonator are resonators according to any one of claims 1-17.

20. The component of claim 19, wherein: The first resonator and the second resonator are the resonators according to claim 12.

21. The component of claim 20, wherein: The difference between the electromechanical coupling coefficient of the first resonator and the electromechanical coupling coefficient of the second resonator is in the range of 0%-10%.

22. The component according to any one of claims 20-21, wherein: The first resonator and the second resonator are both resonators according to claim 14 or 16. The widths of the acoustic resist layer of the first resonator and the corresponding acoustic resist layer of the second resonator are different.

23. A method for manufacturing a bulk acoustic resonator, the resonator comprising a substrate, an acoustic mirror, a bottom electrode, a piezoelectric layer, and a top electrode, the piezoelectric layer comprising a first layer and a second layer, wherein a void layer is provided between the first layer and the second layer at the non-electrode connection end of the top electrode, the method comprising the steps of: The sacrificial layer is formed and graphically represented on the first layer; and The second layer covers the first layer and the sacrificial layer above it. in: The method further includes the steps of: removing the second layer by etching at the non-electrode connection end of the top electrode to expose the outer end of the sacrificial layer; and releasing the sacrificial layer to form the void layer, the outer edge of the void layer being flush with the end of the second layer; or The method further includes the steps of: forming a release channel in the second layer, extending through the second layer in the thickness direction, on the outside of the non-electrode connection end of the top electrode; and releasing the sacrificial layer via the release channel to form the void layer.

24. A filter comprising a bulk acoustic resonator according to any one of claims 1-17, or a bulk acoustic resonator assembly according to any one of claims 18-22.

25. An electronic device comprising the filter of claim 24, or the bulk acoustic resonator of any one of claims 1-17, or the bulk acoustic resonator assembly of any one of claims 18-22.

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