Bulk acoustic resonator and manufacturing method thereof, filter, electronic device

Abstract

The present invention provides a bulk acoustic resonator and its manufacturing method, a filter, and an electronic device, in which a frame structure is installed at the edge of an effective resonance area defined by the bulk acoustic resonator, and the acoustic impedance of the effective resonance area corresponding to the frame structure is greater than the acoustic impedance of the effective resonance area other than the frame structure, so that parasitic transverse waves can be effectively suppressed. The frame structure adopts a double passivation layer structure, which realizes the suppression of transverse waves and at the same time reduces clutter caused by extra resonance. At the same time, the adoption of the double passivation layer structure can reduce stress and improve structural stability and Q value.

Description

[Technical field]

[0001] The present invention relates to the technical field of semiconductors, in particular to a bulk acoustic resonator and its manufacturing method, a filter, and an electronic device. This application claims priority to a Chinese patent application filed with the China Patent Office on December 23, 2022, bearing application number 202211663396.9 and entitled "Bulk Acoustic Resonator and Its Manufacturing Method, Filter, and Electronic Device", the entire contents of which are incorporated herein by reference. [Background technology]

[0002] The basic structure of a bulk acoustic resonator is a "sandwich" structure consisting of a bottom electrode, a piezoelectric layer, and a top electrode. When a high-frequency electrical signal is applied between the top and bottom electrodes, a bulk acoustic wave (BAW) is excited in the piezoelectric layer, propagating along the thickness direction of the piezoelectric layer, due to the inverse piezoelectric effect of the piezoelectric layer. The transmission path length of the bulk acoustic wave is the sum of the thicknesses of the top electrode, bottom electrode, and piezoelectric layer. When a certain relationship is satisfied between the wavelength of the bulk acoustic wave and the propagation path length, a standing wave vibration occurs. In this case, the signal resonates inside the material, and an extremum appears in the equivalent impedance of the device. To optimize the expression of the bulk acoustic wave in the high band (above 1 GHz), the optimal solution is to reduce the "sandwich" structure from a block structure to a thin film structure.

[0003] Currently, the structure of bulk acoustic resonators is divided into solid mounted resonator (SMR) acoustic resonators that use a Bragg reflector layer structure, and back-etching type and air-gap type acoustic resonators that use air as a reflecting medium. Strictly speaking, back-etching type and air-gap type acoustic resonators that use air as a reflecting medium are called thin film bulk acoustic resonators (FBAR), and acoustic resonators that use a Bragg reflector layer are generally called SMR-BAW.

[0004] As a radio frequency device, FBAR needs one radio frequency voltage applied to two electrodes to become a power source. Under the action of radio frequency voltage, an AC electric field is generated in the piezoelectric layer, and due to the inverse piezoelectric effect, the piezoelectric layer is distorted, which is expressed as the vibration of phonons microscopically, and the sound wave is formed macroscopically, which is a bulk acoustic wave inside the piezoelectric body, and through this process, the electrical energy is converted into mechanical energy. The bulk acoustic wave is reflected back and forth between the top electrode and the bottom electrode, and depending on the standing wave formation conditions, when the propagation distance of the sound wave is half a wavelength or an odd multiple of half a wavelength, a standing wave vibration occurs. Due to the positive piezoelectric effect, the reciprocating bulk acoustic wave further excites a radio frequency electrical signal, which further completes the conversion of mechanical energy to electrical energy and forms the resonance of the electrical signal.

[0005] According to the relationship between the polarization direction and the propagation direction of the bulk acoustic wave, the vibration mode of the FBAR can be divided into longitudinal mode and transverse mode. The longitudinal mode is the main resonance, in which the longitudinal wave moves periodically in the opposite direction between the electrodes and exhibits the same phase at all positions of the electrodes, and the longitudinal wave propagates along the Z-axis direction of the piezoelectric layer of the FBAR, and a cavity structure is set up between the substrate and the bottom electrode to reflect the longitudinal wave back to the resonance area at the boundary between the bottom electrode and air, thereby avoiding the loss of acoustic wave energy. The transverse mode is a parasitic mode, in which the resonator generates transverse waves at the same time as the longitudinal waves are generated, and the vibration of the transverse waves causes energy leakage at the boundary of the effective area of ​​the resonator, causing energy loss, which adversely affects the Q value.

[0006] In order to reduce the influence of the transverse mode on the Q value, a frame structure can be installed at the edge position within the effective resonance region of the top electrode, and the frame structure is usually made of the same material as the top electrode, that is, the frame structure is actually a part of the top electrode. The above frame structure does have a beneficial effect on the Q value. However, at the same time, since the metal frame structure electrically connected to the top electrode is itself within the effective resonance region, it suppresses the transverse wave while introducing new spurious signals, which adversely affects the longitudinal mode. Summary of the Invention [Problem to be solved by the invention]

[0007] Therefore, how to reduce the effect of transverse modes on the Q value while avoiding noise has become a major issue that filter design engineers need to consider. [Means for solving the problem]

[0008] In view of this, embodiments of the present invention provide a bulk acoustic resonator and a manufacturing method thereof, a filter, and an electronic device, so as to achieve the objective of avoiding noise while reducing the effect of transverse modes on the Q value.

[0009] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions.

[0010] A first aspect of an embodiment of the present invention discloses a bulk acoustic resonator, comprising: a substrate; a bottom electrode, a piezoelectric layer, and a top electrode stacked on the substrate; an acoustic reflection structure is provided between the substrate and the bottom electrode; and an overlapping area between the bottom electrode, the piezoelectric layer, the top electrode, and the acoustic reflection structure is defined as an effective resonance area of ​​the bulk acoustic resonator; The frame structure further includes a frame structure disposed on an edge of the effective resonance area, the frame structure including a second passivation layer, a first material layer, and a first passivation layer stacked above the top electrode, the frame structure having one end located within the effective resonance area and the other end extending at least until it is flush with the edge of the effective resonance area, and the acoustic impedance of the effective resonance area corresponding to the frame structure is greater than the acoustic impedance of the effective resonance area other than the frame structure.

[0011] Optionally, the first material layer is a metallic material.

[0012] Optionally, the first layer of material is a non-metallic material.

[0013] Optionally, the first layer of material is integral with a second passivation layer.

[0014] Optionally, the frame structure further includes a second material layer disposed between the first material layer and the first passivation layer.

[0015] Optionally, the material of the second layer of material is different from the material of the first passivation layer, and the material of the second layer of material is different from the material of the second passivation layer.

[0016] Optionally, the second layer of material is a metal.

[0017] Optionally, the first passivation layer and the second passivation layer together cover an active resonance region.

[0018] Optionally, the first passivation layer covers the effective resonance area and the second passivation layer is disposed on the edge of the effective resonance area, or the second passivation layer covers the effective resonance area and the first passivation layer is disposed on the edge of the effective resonance area.

[0019] Optionally, the acoustic impedance of the second passivation layer is greater than the acoustic impedance of the first passivation layer.

[0020] In one embodiment of the present invention, the acoustic impedance of the second passivation layer is larger than the acoustic impedance of the first passivation layer, which can reduce acoustic loss and is advantageous for suppressing parasitic transverse waves.

[0021] Optionally, the acoustic impedance of an effective resonance area corresponding to the frame structure is equal to or greater than the acoustic impedance of an area other than the frame structure.

[0022] Optionally, the acoustically reflective structure is a Bragg reflecting layer or a cavity.

[0023] Optionally, the cavity is located within or above the substrate.

[0024] Optionally, the device may further include a first dielectric layer and a second dielectric layer, the first dielectric layer being disposed between the bottom electrode and the second dielectric layer, a third material layer being disposed between the first dielectric layer and the second dielectric layer, the third material layer being disposed at an edge of an effective resonance area, one end of the third material layer being located inside the effective resonance area and the other end extending at least until it is flush with the edge of the effective resonance area, and the acoustic impedance of the effective resonance area corresponding to the third material layer being greater than the acoustic impedance of the effective resonance area other than the third material layer.

[0025] Optionally, the third material layer is integral with the first dielectric layer.

[0026] Optionally, an upper surface of the first layer of material is provided as a textured surface.

[0027] Optionally, the top surface of the second layer of material is provided as a textured surface.

[0028] Optionally, the top surface of the portion of the first passivation layer corresponding to the first material layer is arranged as an uneven surface, and the uneven positions are arranged alternately with the uneven positions of the uneven top surface of the first material layer.

[0029] Optionally, the top surface of the portion of the first passivation layer corresponding to the second material layer is arranged as an uneven surface, and the uneven positions are arranged alternately with the uneven positions of the uneven top surface of the second material layer.

[0030] By providing the top surface of the first passivation layer, the first material layer and / or the second material layer as an uneven top surface, minute parasitic transverse waves near fs can be eliminated or improved.

[0031] A second aspect of an embodiment of the present invention discloses a method for manufacturing a bulk acoustic resonator, comprising: providing a substrate, sequentially forming a bottom electrode, a piezoelectric layer, and a top electrode over the substrate, and forming an acoustic reflection structure between the substrate and the bottom electrode, wherein an overlapping area between the bottom electrode, the piezoelectric layer, the top electrode, and the acoustic reflection structure is defined as an effective resonance area of ​​a bulk acoustic resonator; The frame structure further includes a frame structure formed on an edge of the effective resonance area, the frame structure including a second passivation layer, a first material layer, and a first passivation layer formed sequentially above the top electrode, the frame structure having one end located within the effective resonance area and the other end extending at least until it is flush with the edge of the effective resonance area, and the acoustic impedance of the effective resonance area corresponding to the frame structure is greater than the acoustic impedance of the effective resonance area other than the frame structure.

[0032] A third aspect of the present invention discloses a filter, comprising a bulk acoustic resonator as disclosed in the first aspect of the present invention.

[0033] A fourth aspect of the present invention discloses an electronic device, comprising the bulk acoustic resonator disclosed in the first aspect of the present invention.

[0034] In the embodiment of the present invention, a frame structure is installed at the edge of the effective resonance area defined by the bulk acoustic resonator, and the acoustic impedance of the effective resonance area corresponding to the frame structure is greater than the acoustic impedance of the effective resonance area other than the frame structure, so that the parasitic transverse waves can be effectively suppressed. The frame structure adopts a double passivation layer structure, which realizes the suppression of the transverse waves and at the same time reduces the clutter caused by the extra resonance. At the same time, the double passivation layer structure can reduce stress, improve the structural stability and the Q value, and the first passivation layer in the double passivation layer structure is a frequency modulation layer, which can avoid the deterioration of the frame structure during the frequency modulation process. [Brief description of the drawings]

[0035] In order to more clearly describe the technical solutions in the embodiments of the present invention or the prior art, the following briefly introduces drawings necessary for the description of the embodiments or the prior art. Obviously, the drawings in the following description are embodiments of the present invention, and those skilled in the art may obtain other drawings according to the drawings provided under the premise of not exerting any labor worthy of inventive step. [Figure 1] 1 is a schematic cross-sectional view of a bulk acoustic resonator according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a schematic cross-sectional view of another bulk acoustic resonator provided by an embodiment of the present invention. [Diagram 3] 3 is a frequency impedance graph with respect to the number of clutters, emulated based on FIG. 2; [Figure 4] 3 is a frequency impedance graph relating to the amplitude value of clutter, emulated based on FIG. 2; [Diagram 5] 3 is a frequency impedance graph for Rs value obtained by emulation based on FIG. 2. [Figure 6] 3 is a frequency impedance graph with respect to Rp value obtained by emulation based on FIG. 2. [Figure 7] 3 is a frequency impedance graph for fp obtained by emulation based on FIG. 2. [Figure 8] FIG. 2 is a schematic cross-sectional view of another bulk acoustic resonator provided by an embodiment of the present invention. [Figure 9] FIG. 2 is a schematic cross-sectional view of another bulk acoustic resonator provided by an embodiment of the present invention. [Figure 10] FIG. 2 is a schematic cross-sectional view of another bulk acoustic resonator provided by an embodiment of the present invention. [Figure 11] FIG. 2 is a schematic cross-sectional view of another bulk acoustic resonator provided by an embodiment of the present invention. [Figure 12] FIG. 2 is a schematic cross-sectional view of another bulk acoustic resonator provided by an embodiment of the present invention. [Figure 13] FIG. 2 is a schematic cross-sectional view of another bulk acoustic resonator provided by an embodiment of the present invention. [Figure 14]FIG. 2 is a schematic cross-sectional view of another bulk acoustic resonator provided by an embodiment of the present invention. [Figure 15] FIG. 2 is a schematic cross-sectional view of another bulk acoustic resonator provided by an embodiment of the present invention. [Figure 16] FIG. 2 is a schematic cross-sectional view of another bulk acoustic resonator provided by an embodiment of the present invention. [Figure 17] 17 is a frequency impedance graph with respect to the number of clutters, emulated based on FIG. 16. [Figure 18] 17 is a frequency impedance graph relating to the amplitude value of clutter, emulated based on FIG. 16. [Figure 19] 17 is a frequency impedance graph for Rs value obtained by emulation based on FIG. 16. [Figure 20] 17 is a frequency impedance graph with respect to Rp value obtained by emulation based on FIG. 16. [Figure 21] FIG. 2 is a schematic cross-sectional view of another bulk acoustic resonator provided by an embodiment of the present invention. [Figure 22] FIG. 2 is a schematic cross-sectional view of another bulk acoustic resonator provided by an embodiment of the present invention. [Figure 23] FIG. 2 is a schematic cross-sectional view of another bulk acoustic resonator provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] The technical solutions in the embodiments of the present invention are described below in a clear and complete manner in combination with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the present invention, not all of the embodiments. All other embodiments obtained based on the embodiments of the present invention without the creative labor of those skilled in the art are within the scope of protection of the present invention.

[0037] In this application, terms such as "consisting of," "including," or other variations thereof, are meant to be non-exclusively inclusive. A process, method, product, or apparatus comprising a series of elements includes not only those elements, but also other elements not expressly listed, or further includes elements that were already present in such process, method, product, or apparatus. Furthermore, unless more restrictive, an element defined by the phrase "comprising a..." does not exclude the presence of further identical elements in the process, method, product, or apparatus.

[0038] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a number of technical solutions related to the embodiments of the present invention will be described clearly and completely in conjunction with the drawings in the embodiments of the present invention.

[0039] Example 1 As shown in FIG. 1, a cross-sectional schematic diagram of a bulk acoustic resonator according to a first embodiment of the present invention is shown. The bulk acoustic resonator includes: The bulk acoustic resonator includes a substrate 1, a bottom electrode 2, a piezoelectric layer 3, and a top electrode 4 stacked on the substrate 1, and an acoustic reflection structure 5 is disposed between the substrate 1 and the bottom electrode 2. The overlapping area of ​​the bottom electrode 2, the piezoelectric layer 3, the top electrode 4, and the acoustic reflection structure 5 is defined as the effective resonance area of ​​the bulk acoustic resonator.

[0040] The semiconductor device further includes a frame structure 6 disposed on an edge of the effective resonance region, and the frame structure 6 includes a second passivation layer 7, a first material layer 8, and a first passivation layer 9 laminated above the top electrode 4, and the second passivation layer 7 is disposed between the first passivation layer 9 and the top electrode 4. The first material layer 8 is disposed between the first passivation layer 9 and the second passivation layer 7.

[0041] One end of the frame structure 6 is located within the effective resonance area and the other end extends at least until it is flush with the edge of the effective resonance area, and the acoustic impedance of the effective resonance area corresponding to the frame structure 6 is greater than the acoustic impedance of the effective resonance area other than the frame structure 6, thereby effectively reflecting or suppressing parasitic transverse waves.

[0042] In the first embodiment of the present invention, the frame structure 6 is specifically a second passivation layer 7, a first material layer 8 and a first passivation layer 9 stacked above the top electrode 4 at the edge of the effective resonance region.

[0043] Specifically, one end of the frame structure 6 may be located within the effective resonance area, and the other end of the frame structure 6 may be aligned with the end edge of the top electrode 4 or the bottom electrode 2, or both ends of the frame structure 6 may be located on both sides of the end edges of the top electrode 4 or the bottom electrode 2, respectively, thereby forming a frame with an annular protrusion structure or a frame with a polygonal protrusion structure that matches the boundary of the bottom electrode 2 or the top electrode 4 so that the acoustic impedance of the effective resonance area corresponding to the frame structure 6 is greater than the acoustic impedance of the effective resonance area other than the frame structure 6.

[0044] The acoustic reflection structure 5 in the first embodiment of the present invention is a cavity, and the cavity is located inside the substrate 1. The first passivation layer 9 and the second passivation layer 7 both extend to the effective resonance area and cover the effective resonance area.

[0045] In addition, in a bulk acoustic resonator, Rs represents the sum of the resistance loss and lead loss of the device itself, and Rp represents the energy factor of the bulk acoustic resonator device, and the higher Rp is, the smaller the acoustic loss represented by Rs is, and the more energy of the bulk acoustic resonator participating in the main resonance is, so the higher Rp is, the higher the Q value of the device is, and the better the acoustic structure of the corresponding device is. Therefore, when designing a bulk acoustic resonator device, at the same frequency, it is preferable that Rs is smaller, and Rp is larger.

[0046] The frame structure 6 of the first embodiment of the present invention is different from the metal protrusion structure in the prior art, the frame structure 6 is electrically isolated from the top electrode 4, and is completely made of non-metallic material, which can form a good transverse wave suppression effect, and different from the metal protrusion structure in the prior art that is electrically connected to the top electrode, the conventional protrusion structure is generally formed by performing lift-off processing after deposition, which has a problem of reliability of bonding force between the top electrode and the protrusion structure, and has a risk of layering. In the present invention, the passivation layer is generally formed by CVD process or PVD process, which can form a good bonding force, and at the same time, the frame structure 6 of the present invention reduces the clutter near fs by reducing the extra vibration formed in the vibration stack.

[0047] In one embodiment of the present invention, the first material layer 8 and the second passivation layer 7 are made of the same material and can be molded as one piece.

[0048] The first passivation layer 9 in the first embodiment of the present invention is a frequency modulation layer, which can avoid the occurrence of deterioration to the frame structure 6 during the frequency modulation process. The frequency modulation function is realized by the first passivation layer 9, and the function of reducing lateral wave loss is realized by the second passivation layer 7 and the first material layer 8. Such an installation can avoid the deterioration of the frame structure 6 due to the frequency modulation process, that is, avoid the process contradictions that arise when realizing different functions.

[0049] The material of the first material layer 8 may be a non-metal different from that of the first passivation layer 9 or the second passivation layer 7 .

[0050] The first passivation layer 9 and the second passivation layer 7 can be made of the following media materials, including, but not limited to, SiO2, Si3N4, AlN, Si, SiC, Ta2O5, Al2O3, TiO2, HfO2, ZrO2, MgO, or DLC (diamond like carbon).

[0051] In the process of specifically selecting the medium materials constituting the first passivation layer 9 and the second passivation layer 7, considering that the acoustic impedance in the longitudinal wave direction (in this application document, acoustic impedance means the acoustic impedance in the longitudinal wave direction, unless otherwise specified) is generally in the range of 10 to 100 MRayls, the first passivation layer 9 and the second passivation layer 7 can be optimally selected according to the device model, for example, Si3N4, Ta2O5 or SiC with high acoustic impedance can be selected, where the acoustic impedance of Si3N4 is 36 MRayls, the acoustic impedance of Ta2O5 is 39 MRayls, and the acoustic impedance of SiC is 91 MRayls, and in particular, the acoustic impedance of the medium material SiC is much higher than that of general medium materials.

[0052] In one embodiment of the present invention, the second passivation layer 7 may be composed of multiple layers of materials with different acoustic impedances.

[0053] The first passivation layer 9 and the second passivation layer 7 may be made of a high sound velocity material, such as AlN with a sound velocity of 11,200 m / s, SiC with a sound velocity of 13,000 m / s, Al2O3 with a sound velocity of 10,520 m / s, or Si3N4 with a sound velocity of 11,000 m / s (the measurement results of the above sound velocity data vary slightly depending on the literature).

[0054] The first passivation layer 9 and the second passivation layer 7 using high acoustic velocity materials are advantageous in reducing their respective thicknesses, i.e., reducing the overall thickness of the passivation layers, while reducing the proportion of the thicknesses of the first passivation layer 9 and the second passivation layer 7 in the total vertical thickness of the entire device structure, thereby ensuring the effective electromechanical coupling coefficient and improving the performance of the device.

[0055] In the first embodiment and the following other embodiments of the present invention, the width and thickness of the frame structure 6 can be optimally set according to the performance of the device.

[0056] In one embodiment of the present invention, the width of the frame structure 6 can range from 1 μm to 5 μm, and the thickness can range from 10 nm to 200 nm. For materials with high acoustic impedance, the thin thickness excites spurious modes near fs, reducing device performance. The optimal width of the frame structure 6 is related to the frequency and also to the thickness, and a collaborative optimization can be performed to select the optimal placement.

[0057] In the present invention, since the frequency modulation process is a process of modifying the frequency, this process is basically similar to the etching process, with the difference being that the frequency modulation process does not etch the entire wafer at once, but sweeps the entire wafer with, for example, a snake-shaped trajectory, and different etching or modification amounts may be applied to different areas of the entire wafer. The principle of the frequency modulation process is to reduce the thickness of the thin film by physical impact with a particle beam, and the thin film may be reduced by physical impact and chemical reaction at the same time. Therefore, after frequency modulation, the thicknesses of the first passivation layer 9 in different areas all have different removal amounts to achieve the design target frequency, but the thickness and width of other parts of the frame structure 6 remain unchanged, which can ensure that the acoustic physical model of the device does not change, ensure the consistency of the device performance, and increase the yield.

[0058] In the first embodiment and the other embodiments described below, a first passivation layer 9 and a second passivation layer 7 having different acoustic impedances are formed above the top electrode 4 within the effective resonance region.

[0059] In one embodiment of the present invention, the acoustic impedance of the second passivation layer 7 close to the top electrode 4 is greater than the acoustic impedance of the first passivation layer 9 .

[0060] Based on this, the second passivation layer 7 can be selected as SiC, and the first passivation layer 9 can be selected as Al2O3. Alternatively, the second passivation layer 7 can be set to have a positive stress and the first passivation layer 9 can be set to have a negative stress, so that the stresses are offset from each other to improve the reliability of the structure. When the bottom electrode 2, the top electrode 4 and the piezoelectric layer 3 grow, setting the stress to achieve the stress balance will affect the performance of the device, and in this case, the stress and the performance cannot be achieved at the same time. Therefore, the combined installation of the first passivation layer 9 and the second passivation layer 7 can achieve the stress balance, and further improve the structural stability and Q value.

[0061] That is, when the frame structure 6 is installed with both passivation layers, i.e. the first passivation layer 9 and the second passivation layer 7 are installed at the same time, a stress balance can be achieved, in which case the stress installation of the bottom electrode 2, the top electrode 4 and the piezoelectric layer 3 only needs to ensure the best performance.

[0062] In the bulk acoustic resonator disclosed in the first embodiment of the present invention, a frame structure 6 is provided at the edge of the effective resonance region defined by the bulk acoustic resonator, which is favorable for reducing stress and making the residual stress between the bottom electrode 2, the top electrode 4 and the piezoelectric layer 3 close to zero after the sacrificial layer is released in the cavity of the bulk acoustic resonator device, thereby improving the working life and stability of the bulk acoustic resonator device. Meanwhile, optimizing the thickness ratio according to its acoustic impedance coefficient is favorable for suppressing transverse waves and achieving the best performance.

[0063] Furthermore, the frame structure 6 with double passivation layers is applied to the BAW filter with SMR structure, i.e., the Bragg reflection layer is placed under the bottom electrode 2 as the acoustic reflection structure 5, and the Bragg reflection layer is composed of alternating high impedance material and low impedance material. In the SMR-BAW resonator, placing the frame structure 6 on the top electrode 4 can improve the Rp performance described above.

[0064] Example 2 FIG. 2 is a schematic cross-sectional view of another bulk acoustic resonator provided by the second embodiment of the present invention.

[0065] The difference between the second embodiment of the present invention and the first embodiment of the present invention is that in the second embodiment of the present invention, the cavity is located above the surface of the substrate 1, and the frame structure 6 ends at the edge of the effective resonance area. Specifically, as shown in FIG. 2, one end of the frame structure 6 is located within the effective resonance area, and the other end is flush with the edge of the top electrode 4.

[0066] In order to compare the effects on resonator performance when the first material layer 8 is made of a metal material and when it is made of a non-metallic material, the applicant conducted a comparative verification using the structure of Example 2 of the present invention as an emulation device structure. The first material layer 8 in the control group is Mo metal, and a Mo metal layer is used instead of the second passivation layer 7 in Example 2, while the first material layer 8 and the second passivation layer 7 in the experimental group are made of the same material, which are silicon carbide, aluminum nitride, and silicon nitride, respectively.

[0067] In the control group and the experimental group, the material of the bottom electrode 2 and the top electrode 4 of the emulation device are both molybdenum, the thickness of the bottom electrode 2 and the top electrode 4 are both 0.3 μm, the material of the piezoelectric layer 3 is aluminum nitride, the thickness of the piezoelectric layer 3 is 0.8 μm, the material of the first passivation layer 9 is aluminum nitride, the thickness of the first passivation layer 9 is 0.29 μm, the thickness of the first material layer 8 and the second passivation layer 7 are both 0.05 μm, and the width of the first material layer 8 is 2 μm.

[0068] Specifically, as shown in FIG. 3 to FIG. 7, the emulation results of the performance parameters of the control group and the experimental group are shown.

[0069] As shown in Figures 3 and 4, compared to the control group, the experimental group has a smaller number of clutters near the series resonance frequency in the frequency impedance curve, and a smaller amplitude value (in this application document, the amplitude value indicates the difference between the maximum and minimum points of the clutter area).

[0070] Specifically, in the frame structure 6, when molybdenum is used for the first material layer 8, the amplitude value is 15, and when non-metallic materials such as silicon carbide, aluminum nitride or silicon nitride are used for the first material layer 8, the amplitude value is 10.

[0071] Since the smaller the amplitude value, the better the device performance, when the first material layer 8 of the frame structure 6 is made of non-metallic materials such as silicon carbide, aluminum nitride or silicon nitride, the clutter suppression effect is obviously better than that of the first material layer 8 made of molybdenum material electrically connected to the top electrode 4.

[0072] Table 1 shows the material properties of molybdenum, aluminum nitride, silicon carbide and silicon nitride.

[0073] The acoustic impedance of the frame structure 6 formed by adopting the first passivation layer 9 of different materials is different, specifically, the calculation formula of the acoustic impedance is Z=ρv, where ρ represents the material density and v represents the longitudinal wave sound velocity.

[0074] It should be noted that the relevant parameters of molybdenum, aluminum nitride, silicon carbide and silicon nitride are slightly different in the conventional literature.

[0075] [Table 1]

[0076] At the same time, as shown in Figure 5, near the series resonance frequency fs, compared with the control group, Rs and fs of the experimental group are basically unchanged, that is, the Rs values ​​corresponding to molybdenum, silicon carbide, aluminum nitride and silicon nitride are close to the series resonance frequency fs, that is, the Rs values ​​corresponding to different materials are close, all around 1.1Ω, and fs are also close, all around 2.231GHz, which is favorable for maintaining the quality factor Qs at the series resonance frequency.

[0077] As shown in FIGS. 6 and 7, in the vicinity of the parallel resonance frequency, Rp of the experimental group is obviously improved compared to that of the control group.

[0078] Specifically, the Rp value obtained differs depending on the material used for the first material layer 8. The Rp value obtained when silicon carbide was used for the first material layer 8 was 4010Ω, the Rp value obtained when aluminum nitride was used for the first material layer 8 was 3991Ω, the Rp value obtained when silicon nitride was used for the first material layer 8 was 3928Ω, and the Rp value obtained when molybdenum was used for the first material layer 8 was 3512Ω.

[0079] The higher the Rp value, the better the device performance; that is, the frame structure 6 using silicon carbide is superior to the frame structure 6 using aluminum nitride, which is superior to the frame structure 6 using silicon nitride, which is superior to the frame structure 6 of the control group.

[0080] Thus, under the same installation conditions, the experimental group can achieve higher Rp performance than the control group, and the performance of the device is significantly improved; for example, when silicon carbide material is used for the first material layer 8 in the frame structure 6, the Rp is improved by 14% compared to that of the control group.

[0081] At the same time, compared with the control group, the quality factor Qp of the experimental group is improved, and the suppression effect against transverse waves is better.

[0082] Furthermore, compared to the control group, the parallel resonance frequencies (ie, peak values) of the experimental group are all shifted to the right and essentially overlap, with a frequency of about 2.297 GHz.

[0083] In fact, compared to the control group (fp is 2.295 GHz), the parallel resonance frequency of the experimental group is improved by about 2 MHz.

[0084] According to the emulation results, the piezoelectric coupling coefficient is calculated as follows: Compared with the control group, the Kt of the bulk acoustic resonator device in the experimental group is 2 increased by 0.2% (original Kt 2 (2.99% of the value of 6.69), i.e., up from 6.69 to 6.89.

[0085] Therefore, the performance of the bulk acoustic resonator device can be further improved, for example, the out-of-band suppression can be improved while the insertion loss remains unchanged, and the yield of the bulk acoustic resonator device can be increased by about 3%, which directly reduces the cost of mass production of the bulk acoustic resonator device.

[0086] In another embodiment, the first material layer 8 of the frame structure 6 may be made of a material different from both the second passivation layer 7 and the first passivation layer 9 .

[0087] In the second embodiment of the present invention, the non-metallic first material layer not only reduces the width of the clutter near fs, but also ensures good Rp performance. In addition, compared with the control group, the Kt 2 can be further improved, further improving the performance of the bulk acoustic resonator device.

[0088] Example 3 FIG. 8 is a schematic cross-sectional view of another bulk acoustic resonator provided by the third embodiment of the present invention.

[0089] The difference between the embodiment 3 of the present invention and the embodiment 2 of the present invention is that the frame structure 6 in the embodiment 3 of the present invention further includes a second material layer 10, which is located between the first material layer 8 and the first passivation layer 9, and one end of the second material layer 10 is located inside the effective resonance region and the other end is aligned with the edge of the effective resonance region.

[0090] The material of the second material layer 10 is a metal, or both the first passivation layer 9 and the second passivation layer 7 are different non-metals.

[0091] In the third embodiment of the present invention, by disposing a second material layer between the first material layer and the first passivation layer, the frame structure becomes a multi-layer composite structure, which further improves the overall performance of the bulk acoustic resonator.

[0092] Example 4 FIG. 9 is a schematic cross-sectional view of another bulk acoustic resonator provided by the fourth embodiment of the present invention.

[0093] The difference between the fourth embodiment of the present invention and the first embodiment of the present invention is that the frame structure 6 in the fourth embodiment of the present invention further includes a first dielectric layer 11 and a second dielectric layer 12, and the first dielectric layer 11 is disposed between the bottom electrode 2 and the second dielectric layer 12, specifically, the first dielectric layer 11 is located below the bottom electrode 2 and the piezoelectric layer 3.

[0094] The second dielectric layer 12 is located below the first dielectric layer 11, and a third material layer 13 is provided between the first dielectric layer 11 and the second dielectric layer 12, the third material layer 13 is provided at the edge of the effective resonance region, one end of the third material layer 13 is located inside the effective resonance region and the other end extends beyond the edge of the effective resonance region, and the acoustic impedance of the effective resonance region corresponding to the third material layer 13 is greater than the acoustic impedance of the effective resonance region other than the third material layer 13.

[0095] In one embodiment of the present invention, one end of the third material layer 13 is flush with the end of the first material layer 8 and the other end extends beyond the edge of the effective resonance region.

[0096] In practice, the third material layer 13 is located at the edge of the acoustically reflecting structure 5 so that the other end of said third material layer 13 extends outwards along the bottom electrode 2 and the piezoelectric layer 3 .

[0097] In one embodiment of the present invention, the third material layer 13 is made of the same material as the first dielectric layer 11 and can be molded integrally.

[0098] In one embodiment of the present invention, the first dielectric layer 11 and the second dielectric layer 12 are made of an insulating material.

[0099] Example 5 FIG. 10 is a schematic cross-sectional view of another bulk acoustic resonator provided by the fifth embodiment of the present invention.

[0100] The fifth embodiment of the present invention is different from the first embodiment of the present invention in that the acoustic reflection structure of the fifth embodiment of the present invention is located on the surface of the substrate, and the frame structure 6 has an uneven surface 14.

[0101] Specifically, the uneven surface is provided on the upper surface of the first material layer 8, or the upper surface of the first passivation layer 9 in a portion corresponding to the first material layer 8 is provided as an uneven surface, or the first material layer 8 and the upper surface of the first passivation layer 9 in a portion corresponding to the first material layer 8 are both provided as uneven surfaces, and the uneven positions are arranged alternately with the uneven positions of the uneven surface of the first material layer 8.

[0102] The uneven surface 14 forms an undulating structure on the top surface of the first material layer 8 in the frame structure 6 and / or on the top surface of the first passivation layer 9 corresponding to the first material layer 8. The fact that the first material layer 8 in the frame structure 6 and the uneven surfaces on the corresponding first passivation layer 9 are alternately arranged is advantageous in suppressing the frame structure 6 from introducing new parasitic transverse waves near fs.

[0103] In the fifth embodiment of the present invention, by providing an uneven surface, minute parasitic transverse waves near fs can be improved or eliminated.

[0104] Example 6 As shown in FIG. 11, a cross-sectional schematic diagram of another bulk acoustic resonator provided by the sixth embodiment of the present invention.

[0105] The sixth embodiment of the present invention is distinguished from the first embodiment of the present invention in that the cavity is installed on the substrate 1 to form a ground-type cavity, and the material of the first material layer 8 is a metal, specifically, it may be a high acoustic impedance metal such as tungsten, molybdenum, iridium, platinum, ruthenium or tantalum, typically, a metal with an acoustic impedance of more than 50 MRayls in the longitudinal wave direction can be selected, such as molybdenum with an acoustic impedance of 66 MRayls, tungsten with an acoustic impedance of 99 MRayls, or ruthenium with an acoustic impedance of 73 MRayls.

[0106] In one embodiment of the present invention, a metal with a high sound velocity may also be adopted for the first material layer 8, and selectable high sound velocity materials include, for example, beryllium with a sound velocity of 12890 m / s and lithium with a sound velocity of 7080 m / s.

[0107] Example 7 FIG. 12 is a schematic cross-sectional view of another bulk acoustic resonator provided by the seventh embodiment of the present invention.

[0108] The difference between the embodiment 7 of the present invention and the embodiment 1 of the present invention is as follows. That is, in the embodiment 7 of the present invention, the cavity is disposed on the substrate 1, and the frame structure 6 of the embodiment 7 of the present invention further includes a second material layer 10 disposed between the first material layer 8 and the first passivation layer 9, the material of the second material layer 10 is metal, and the second material layer 10 has one end disposed within the effective resonance region and the other end extending beyond the edge of the effective resonance region along the outer edge of the first material layer 8. The outer side of the first material layer 8 is the side away from the center of the effective resonance region of the first material layer 8, and the inner side of the first material layer 8 is the side close to the center of the effective resonance region of the first material layer 8.

[0109] Near the frame structure 6, the first material layer 8, the first passivation layers 9 on both sides of the first material layer 8, and the second material layer 10 on the outside of the first material layer 8 can form an effect similar to that of a Bragg reflection layer, which is advantageous in limiting the transverse wave within the effective resonance region, and the frame structure 6 is also advantageous in suppressing clutter near fs.

[0110] In the seventh embodiment of the present invention, the second material layer 10 is made of a metal material, and the existence of the second passivation layer 7 can provide electrical isolation between the second material layer 10 made of a metal material and the top electrode 4 .

[0111] Furthermore, the material of the second material layer 10 may be a non-metallic material different from the material of the second passivation layer 7, or a non-metallic material different from the materials of both the first passivation layer 9 and the second passivation layer 7.

[0112] Furthermore, the second material layer 10 extends along the outer edge of the first material layer 8 and then continues to extend along the surface of the second passivation layer 7 to further reduce the amount of acoustic energy lost by shear waves. The side structure may be a multi-layer reflective structure surrounding the electrode.

[0113] In one embodiment of the present invention, the acoustically reflecting structure 5 may be a cavity or a Bragg reflecting structure.

[0114] Example 8 FIG. 13 is a schematic cross-sectional view of another bulk acoustic resonator provided by Example 8 of the present invention.

[0115] The difference between the embodiment 8 of the present invention and the embodiment 1 of the present invention is as follows: in the embodiment 8 of the present invention, one end of the frame structure 6 is located inside the effective resonance area, and the other end exceeds the edge of the effective resonance area, and the height of the upper surface of the first material layer 8 and the second passivation layer 7 remains unchanged, and the height of the upper surface remains unchanged means that the height does not obviously change, but allows for reasonable manufacturing errors in the art.

[0116] Example 9 FIG. 14 is a schematic cross-sectional view of another bulk acoustic resonator provided by Example 9 of the present invention.

[0117] The difference between the embodiment 9 of the present invention and the embodiment 1 of the present invention is that in the embodiment 9 of the present invention, the first passivation layer 9 covers the effective resonance region, that is, compared to the embodiment 1 of the present invention, when forming the first passivation layer 9, the second passivation layer between the inner ends of the frame structure 6 is omitted, and the inner end of the frame structure 6 is the end close to the center of the effective resonance region of the frame structure 6.

[0118] Example 10 FIG. 15 is a schematic cross-sectional view of another bulk acoustic resonator provided by a tenth embodiment of the present invention.

[0119] The tenth embodiment of the present invention is distinguished from the ninth embodiment of the present invention in that one end of the frame structure 6 is located within the effective resonance region, and the other end is flush with the edge of the top electrode 4.

[0120] In one embodiment of the present invention, a different material may be adopted for the first material layer 8 of the frame structure 6 than for the second passivation layer 7 .

[0121] Example 11 FIG. 16 is a schematic cross-sectional view of another bulk acoustic resonator provided by an eleventh embodiment of the present invention.

[0122] The distinction between the embodiment 11 of the present invention and the embodiment 10 of the present invention is that the cavity of the embodiment 11 of the present invention is disposed on the substrate 1, and the frame structure 6 of the embodiment 11 of the present invention further includes a second material layer 10, which is disposed between the first material layer 8 and the first passivation layer 9, and the second material layer 10 has one end located within the effective resonance region and the other end aligned with the edge of the effective resonance region.

[0123] In order to compare the effects on resonator performance when the first material layer 8 is made of a metal material and when it is made of a non-metallic material, the applicant conducted a comparative verification using the structure of Example 11 of the present invention as an emulation device structure. The first material layer 8 in the control group is a Mo metal layer, and a Mo metal layer is used instead of the second passivation layer 7 in Example 11, while the first material layer 8 and the second passivation layer 7 in the experimental group are made of the same material, which are silicon carbide, aluminum nitride, or silicon nitride, respectively.

[0124] The material of the bottom electrode 2 and the top electrode 4 of the emulation device in the control group and the experimental group are both molybdenum, the thicknesses of the bottom electrode 2 and the top electrode 4 are both 0.3 μm, the material of the piezoelectric layer 3 is aluminum nitride, the thickness of the piezoelectric layer 3 is 0.8 μm, the material of the first passivation layer 9 is aluminum nitride, the thickness of the first passivation layer 9 is 0.29 μm, the thicknesses of the second passivation layer 7 and the first material layer 8 are both 0.025 μm, the material of the second material layer 10 is molybdenum and the thickness is 0.05 μm, and the widths of the first material layer 8 and the second material layer 10 are both 2 μm.

[0125] The parameters corresponding to the control group represent a traditional metal bump structure electrically connected to the top electrode 4, and the parameters corresponding to the experimental group represent the structure of an embodiment of the present invention.

[0126] As shown in FIGS. 17 and 18, in comparison with the control group, the experimental group has a smaller number of clutters near the series resonance frequency in the frequency-impedance curve, and a smaller amplitude value.

[0127] Specifically, the amplitude value of the control group is 15, and the amplitude value of the experimental group is 10.

[0128] The smaller the amplitude value, the better the device performance, so the clutter suppression effect of the experimental group is obviously better than that of the control group.

[0129] At the same time, as shown in FIG. 19, near the series resonance frequency fs, Rs and fs of the experimental group basically remain unchanged compared to the control group, and the Rs values ​​corresponding to different materials are close, with the Rs values ​​all being around 1.1 Ω, and fs is also close, with both being around 2.231 GHz, which is favorable for maintaining the quality factor Qs at the series resonance frequency.

[0130] 20, in the vicinity of the parallel resonance frequency fp, the Rp of the experimental group is obviously improved compared to the control group. When the first material layer 8 is made of aluminum nitride and the second material layer 10 is made of metal molybdenum, the Rp value obtained is 4218Ω, when the first material layer 8 is made of silicon carbide and the second material layer 10 is made of metal molybdenum, the Rp value obtained is 4210Ω, when the first material layer 8 is made of silicon nitride and the second material layer 10 is made of metal molybdenum, the Rp value obtained is 4194Ω, and the Rp value obtained by the control group is 3512Ω.

[0131] The higher the Rp value, the better the device performance; that is, a frame structure 6 employing aluminum nitride and molybdenum is superior to a frame structure 6 employing silicon carbide and molybdenum, which is superior to a frame structure 6 employing silicon nitride and molybdenum, which is superior to a frame structure 6 employing molybdenum alone.

[0132] Thus, under the same installation conditions, the experimental group can achieve higher Rp performance than the control group, and the device performance is significantly improved.

[0133] At the same time, compared with the control group, the quality factor Qp of the experimental group is improved, and the suppression effect against transverse waves is better.

[0134] Furthermore, compared with the control group (fp is 2.295 GHz), the parallel resonance frequencies of the experimental group are all shifted to the right and basically overlap, with the frequency being around 2.296 GHz, and the parallel resonance frequency is improved by about 1 MHz.

[0135] The experimental group in the embodiment 11 of the present invention is compared with the experimental group in the embodiment 2 of the present invention in terms of Rs, which is about 1.1Ω for both, and the amplitude value of clutter near fs is still suppressed. However, Rp is better than that of the experimental group in the embodiment 2.

[0136] The experimental group of Example 11 of the present invention had an Rp of around 4200, while in the experimental group of Example 2, the highest Rp was for the frame structure 6 using SiC material, with an Rp of 4010, which is an improvement of about 5% in comparison. Note that in this case, the amplitude value of the clutter does not fundamentally change.

[0137] Example 12 FIG. 21 is a schematic cross-sectional view of another bulk acoustic resonator provided by Example 12 of the present invention.

[0138] The difference between the embodiment 12 of the present invention and the embodiment 7 of the present invention is as follows: in the embodiment 12 of the present invention, the first passivation layer 9 covers the effective resonance region, that is, compared to the embodiment 7 of the present invention, when forming the first passivation layer 9, the second passivation layer between the inner ends of the frame structure 6 is omitted, and the inner end of the frame structure 6 is the end close to the center of the effective resonance region of the frame structure 6.

[0139] Example 13 FIG. 22 is a schematic cross-sectional view of another bulk acoustic resonator provided by a thirteenth embodiment of the present invention.

[0140] The difference between the embodiment 13 of the present invention and the embodiment 6 of the present invention is as follows: in the embodiment 13 of the present invention, the first passivation layer 9 covers the effective resonance region, i.e., compared to the embodiment 6 of the present invention, the second passivation layer between the inner ends of the frame structure 6 is deleted when forming the first passivation layer 9. The inner end of the frame structure 6 is the end close to the center of the effective resonance region of the frame structure 6.

[0141] In another embodiment, the second passivation layer 7 may cover the effective resonance region, i.e., in forming the first passivation layer 9 in relation to embodiment 6 of the present invention, after the first passivation layer 9 encapsulates the second material layer 10, the portion of the first passivation layer 9 that continues to extend into the effective resonance region is removed.

[0142] Example 14 FIG. 23 is a schematic cross-sectional view of another bulk acoustic resonator provided by Example 14 of the present invention.

[0143] The difference between the embodiment 14 of the present invention and the embodiment 8 of the present invention is as follows: in the embodiment 14 of the present invention, the first passivation layer 9 covers the effective resonance region, i.e., compared to the embodiment 8 of the present invention, the second passivation layer between the inner ends of the frame structure 6 is deleted when forming the first passivation layer 9. The inner end of the frame structure 6 is the end close to the center of the effective resonance region of the frame structure 6.

[0144] Based on all the bulk acoustic resonators provided by the above embodiments of the present invention, the embodiments of the present invention correspondingly provide a manufacturing method for a bulk acoustic resonator, for manufacturing any bulk acoustic resonator provided by the above embodiments of the present invention, and the manufacturing method includes steps S11 to S14. S11: Provide a substrate and form a sacrificial layer on the substrate.

[0145] In S11, the substrate includes, but is not limited to, a Si substrate, a sapphire substrate, or a glass substrate.

[0146] The sacrificial layer may be formed using a medium material, including but not limited to SiO2, PSG, Si, Si3N4, or PI, which is subsequently released to obtain an acoustically reflective structure.

[0147] S12: Sequentially form at least a bottom electrode, a piezoelectric layer, and a top electrode above the substrate with a sacrificial layer.

[0148] In S12, for the material of the bottom electrode, tungsten (W), molybdenum (Mo), aluminum (Al), platinum (Pt), ruthenium (Ru) or niobium (Nb) may be adopted, but is not limited thereto.

[0149] For the material of the piezoelectric layer, AlN or AlScN (Sc-doped ALN) may be selected.

[0150] For the material of the piezoelectric layer, yttrium (Y), 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) or lutetium (Lu) doped AlN, or Mg, Hf or Zr doped AlN, or thin film LN (lithium niobate LiNbO3 or lithium tantalate (LiTaO3) may further be selected.

[0151] The material of the top electrode may be, but is not limited to, tungsten (W), molybdenum (Mo), aluminum (Al), platinum (Pt), ruthenium (Ru) or niobium (Nb).

[0152] In the process of performing S12, at least a bottom electrode, a piezoelectric layer and a top electrode of a specific structure are sequentially formed on a substrate having a sacrificial layer.

[0153] S13: Form a frame structure at the edge of the effective resonance region.

[0154] In S13, an overlapping area between the bottom electrode, the piezoelectric layer, the top electrode and the acoustic reflection structure is defined as an effective resonance area of ​​the bulk acoustic resonator, and the frame structure includes a second passivation layer formed above the top electrode, a first material layer and a first passivation layer.

[0155] One end of the frame structure is located within the effective resonance area and the other end extends at least until it is flush with the edge of the effective resonance area, and the acoustic impedance of the effective resonance area corresponding to the frame structure is greater than the acoustic impedance of the effective resonance area other than the frame structure.

[0156] Possible materials for the second passivation layer include, but are not limited to, polysilicon, aluminum nitride, silica, doped silica, silicon carbide, or alumina.

[0157] For the first material layer, a metallic or non-metallic material may be selected.

[0158] Possible materials for the first passivation layer include, but are not limited to, polysilicon, aluminum nitride, silica, doped silica, silicon carbide, or alumina.

[0159] In performing S13, at least a second passivation layer, a first material layer, and a first passivation layer are formed over the top electrode.

[0160] After the first passivation layer is formed, the sacrificial layer is released to obtain an acoustic reflection structure.

[0161] S14: Thin the first passivation layer, complete the frequency modulation, and can thin the first passivation layer by physical and / or chemical methods, and further complete the frequency modulation.

[0162] In the embodiment of the present invention, a frame structure is installed at the edge of the effective resonance area defined by the bulk acoustic resonator, and the acoustic impedance of the effective resonance area corresponding to the frame structure is greater than the acoustic impedance of the effective resonance area other than the frame structure, so that the parasitic transverse waves can be effectively suppressed. The frame structure adopts a double passivation layer structure, which realizes the suppression of the transverse waves and at the same time reduces clutter caused by extra resonance. At the same time, the adoption of the double passivation layer structure can reduce stress and improve the structural stability and Q value.

[0163] Based on the bulk acoustic resonator provided by the above-mentioned embodiment of the present invention, the embodiment of the present invention further provides a filter, which includes any bulk acoustic resonator provided by the above-mentioned embodiment of the present invention.

[0164] Based on the bulk acoustic resonator provided by the above-mentioned embodiments of the present invention, the embodiments of the present invention further provide an electronic device, which includes any of the bulk acoustic resonators provided by the above-mentioned embodiments of the present invention.

[0165] In the description of this application, the orientations or positional relationships indicated by the terms "upper", "lower", "top", "bottom", "inner", "outer", etc. are orientations or positional relationships shown based on the drawings, and are merely for the convenience of explaining and simplifying the description of this application, and are not intended to indicate or imply that the devices or elements referred to have a specific orientation and must be constructed and operated in a specific orientation, and therefore should not be understood as limiting this application. When one assembly is recognized as being "connected" to another assembly, it may be directly connected to the other assembly, or there may be an assembly disposed in the middle at the same time.

[0166] It should be further noted that, as used herein, terms such as "first" and "second" are merely used to distinguish an entity or operation from other entities or operations, and do not necessarily require or imply that any such existential relationship or ordering exists between the entities or operations.

[0167] The above description of the disclosed embodiments enables one skilled in the art to realize or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Thus, the present application is not limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. 1. A bulk acoustic resonator comprising: a substrate; a bottom electrode, a piezoelectric layer, and a top electrode stacked on the substrate; an acoustic reflection structure is provided between the substrate and the bottom electrode; and an overlapping area between the bottom electrode, the piezoelectric layer, the top electrode, and the acoustic reflection structure is defined as an effective resonance area of ​​the bulk acoustic resonator; The present invention further includes a frame structure disposed on an edge of an effective resonance region, the frame structure including a second passivation layer, a first material layer, and a first passivation layer disposed above the top electrode, the frame structure having one end located within the effective resonance region and the other end extending at least until it is flush with the edge of the effective resonance region, and the acoustic impedance of the effective resonance region corresponding to the frame structure is greater than the acoustic impedance of the effective resonance region other than the frame structure. A bulk acoustic resonator comprising:

2. The first material layer is a metal material.

2. The bulk acoustic resonator of claim 1 .

3. the first material layer is a non-metallic material; 2. The bulk acoustic resonator of claim 1 .

4. the first material layer is integral with a second passivation layer; 2. The bulk acoustic resonator of claim 1 .

5. the frame structure further includes a second material layer disposed between the first material layer and the first passivation layer; 2. The bulk acoustic resonator of claim 1 .

6. the material of the second material layer is different from the material of the first passivation layer, and the material of the second material layer is different from the material of the second passivation layer; 6. The bulk acoustic resonator of claim 5.

7. The material of the second material layer is a metal.

6. The bulk acoustic resonator of claim 5.

8. The first passivation layer and the second passivation layer together cover an effective resonance region.

2. The bulk acoustic resonator of claim 1 .

9. The first passivation layer covers an effective resonance region, and the second passivation layer is disposed on an edge of the effective resonance region; or the second passivation layer covers an effective resonance region, and the first passivation layer is disposed on an edge of the effective resonance region; 2. The bulk acoustic resonator of claim 1 .

10. The acoustic impedance of the second passivation layer is greater than the acoustic impedance of the first passivation layer.

2. The bulk acoustic resonator of claim 1 .

11. The acoustic impedance of an effective resonance area corresponding to the frame structure is equal to or greater than the acoustic impedance of an area other than the frame structure.

2. The bulk acoustic resonator of claim 1 .

12. The acoustic reflection structure is a Bragg reflection layer or a cavity.

2. The bulk acoustic resonator of claim 1 .

13. The cavity is located within or above the substrate.

13. The bulk acoustic resonator of claim 12.

14. The piezoelectric element further includes a first dielectric layer and a second dielectric layer, the first dielectric layer being disposed between the bottom electrode and the second dielectric layer, a third material layer being disposed between the first dielectric layer and the second dielectric layer, the third material layer being disposed at an edge of an effective resonance region, one end of the third material layer being located inside the effective resonance region and the other end extending at least until it is flush with the edge of the effective resonance region, and the acoustic impedance of the effective resonance region corresponding to the third material layer is greater than the acoustic impedance of the effective resonance region other than the third material layer.

2. The bulk acoustic resonator of claim 1 .

15. the third material layer is integrally formed with the first dielectric layer; 15. The bulk acoustic resonator of claim 14.

16. The upper surface of the first material layer is provided as a textured surface; 2. The bulk acoustic resonator of claim 1 .

17. The upper surface of the second material layer is provided as a textured surface.

6. The bulk acoustic resonator of claim 5.

18. The upper surface of the portion of the first passivation layer corresponding to the first material layer is provided as an uneven surface, and the uneven positions are alternately provided with the uneven positions of the uneven upper surface of the first material layer; 17. The bulk acoustic resonator of claim 16.

19. The upper surface of the portion of the first passivation layer corresponding to the second material layer is provided as an uneven surface, and the uneven positions are alternately provided with the uneven positions of the uneven upper surface of the second material layer; 20. The bulk acoustic resonator of claim 17.

20. 1. A method for manufacturing a bulk acoustic resonator, comprising the steps of: providing a substrate, sequentially forming a bottom electrode, a piezoelectric layer, and a top electrode over the substrate, and forming an acoustic reflection structure between the substrate and the bottom electrode, wherein an overlapping area between the bottom electrode, the piezoelectric layer, the top electrode, and the acoustic reflection structure is defined as an effective resonance area of ​​a bulk acoustic resonator; the frame structure further includes a frame structure formed on an edge of an effective resonance region, the frame structure including a second passivation layer, a first material layer, and a first passivation layer sequentially formed above the top electrode, the frame structure having one end located within the effective resonance region and the other end extending at least until it is flush with the edge of the effective resonance region, and the acoustic impedance of the effective resonance region corresponding to the frame structure is greater than the acoustic impedance of the effective resonance region other than the frame structure; A method for manufacturing a bulk acoustic resonator comprising the steps of:

21. A filter comprising a bulk acoustic resonator according to any one of claims 1 to 19. A filter characterized by:

22. An electronic device comprising the bulk acoustic resonator according to any one of claims 1 to 19.

1. An electronic device comprising:

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