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

Abstract

The present application relates to a bulk acoustic wave resonator assembly, comprising: a substrate; at least two resonators, the at least two resonators being bulk acoustic wave resonators and stacked in a thickness direction of the substrate on one side of the substrate, the at least two resonators comprising a first resonator and a second resonator, the second resonator being above the first resonator, the first resonator having a first top electrode, a first piezoelectric layer, a first bottom electrode and a first acoustic mirror, the second resonator having a second top electrode, a second piezoelectric layer, a second bottom electrode and a second acoustic mirror, wherein: an acoustic decoupling layer in the form of a cavity is provided between the first top electrode and the second bottom electrode, the acoustic decoupling layer acting as the second acoustic mirror; at least one electrode is provided with an acoustic boundary structure along a boundary of an active area of the corresponding resonator. The present application also relates to a manufacturing method of a bulk acoustic wave resonator assembly, 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 assembly and a method for manufacturing the same, a filter having the resonator assembly, and an electronic device. Background Technology

[0002] With the rapid development of wireless communication technology, the application of miniaturized portable terminal devices is becoming increasingly widespread, leading to a growing demand for high-performance, small-size radio frequency front-end modules and devices. In recent years, filter devices such as filters and duplexers based on thin-film acoustic resonators (FBARs) have become increasingly popular in the market. This is due to their excellent electrical performance, including low insertion loss, steep transition characteristics, high selectivity, high power capacity, and strong electrostatic discharge (ESD) resistance; and also to their small size and ease of integration.

[0003] However, in reality, there is a need to further reduce the size of filtering devices.

[0004] Furthermore, in existing designs, bulk acoustic wave resonators are combined in series and parallel to form filters. This requires multiple resonators to be formed on a substrate, with each resonator located at a different horizontal position on the substrate and connected by horizontal metal leads, such as... Figure 1 As shown, the dotted box indicates that the top electrode 104 of the resonator 100 is connected to the bottom electrode 102 of the resonator 200 through a conductive via v. To ensure signal transmission and meet manufacturing process limitations, the connection width between the conductive via v and the top electrode 104 of the resonator 100, the width of the conductive via v, the width of the top electrode 104 of the resonator 100, and the width of the bottom electrode 102 of the resonator 200 all have certain requirements. Generally, the total length is >5μm. This leads to the introduction of large electrical losses by the connection line, especially for high-frequency resonators. When the electrode thickness is <1000A, the insertion loss will deteriorate by more than 0.1dB.

[0005] Furthermore, in practical applications, there is still a need to further suppress the transverse vibration mode of the acoustic waves to increase the parallel resonant impedance Rp of the resonator, thereby improving the Q value of the resonator. 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 assembly is provided, comprising:

[0008] Base;

[0009] At least two resonators, which are bulk acoustic wave resonators, are stacked on one side of a substrate in the thickness direction of the substrate. The at least two resonators include a first resonator and a second resonator, with the second resonator above the first resonator. The first resonator has a first top electrode, a first piezoelectric layer, a first bottom electrode, and a first acoustic mirror. The second resonator has a second top electrode, a second piezoelectric layer, a second bottom electrode, and a second acoustic mirror.

[0010] in:

[0011] An acoustic decoupling layer in the form of a cavity is provided between the first top electrode and the second bottom electrode, and the acoustic decoupling layer serves as the second acoustic mirror;

[0012] At least one electrode is provided with an acoustic boundary structure along the boundary of the effective region of the corresponding resonator.

[0013] Embodiments of the present invention also relate to a bulk acoustic resonator assembly, comprising:

[0014] At least two resonators are stacked adjacent to each other from bottom to top in the thickness direction of the component. The at least two resonators are bulk acoustic resonators, and the at least two resonators include a first resonator and a second resonator, wherein:

[0015] An acoustic decoupling layer in the form of a cavity is disposed between the top electrode of the first resonator and the bottom electrode of the second resonator, and the acoustic decoupling layer serves as an acoustic mirror for the second resonator; and

[0016] At least one electrode is provided with an acoustic boundary structure along the boundary of the effective region of the corresponding resonator.

[0017] Embodiments of the present invention also relate to a method for manufacturing a bulk acoustic resonator assembly, comprising:

[0018] Step 1: Form a first structure for a first bulk acoustic resonator on the surface of a substrate, the first bulk acoustic resonator including a first acoustic mirror, a first bottom electrode, a first piezoelectric layer, and a first top electrode;

[0019] Step 2: Apply a patterned sacrificial material layer to the first structure formed in Step 1;

[0020] Step 3: Form a second structure for a second bulk acoustic resonator on the structure of step 2. The second bulk acoustic resonator includes a second acoustic mirror, a second bottom electrode, a second piezoelectric layer, and a second top electrode. The sacrificial material layer is located between the first top electrode and the second bottom electrode in the thickness direction of the substrate.

[0021] Step 4: Release the sacrificial material layer to form a cavity, which constitutes the second acoustic mirror of the second bulk acoustic resonator.

[0022] in:

[0023] At least one of the first top electrode, the second top electrode, the first bottom electrode, and the second bottom electrode has an acoustic boundary structure disposed along the effective region of the corresponding volume acoustic resonator.

[0024] Embodiments of the present invention also relate to a filter, including the aforementioned bulk acoustic resonator assembly.

[0025] Embodiments of the present invention also relate to an electronic device, including the filter or the resonator assembly described above. Attached Figure Description

[0026] 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:

[0027] Figure 1 A schematic cross-sectional view of the electrical connection between two adjacent bulk acoustic resonators in an existing design;

[0028] Figure 2 A schematic top view of a bulk acoustic resonator assembly according to an exemplary embodiment of the present invention;

[0029] Figure 3A For an exemplary embodiment of the present invention, along Figure 2 The schematic cross-sectional view of the bulk acoustic resonator obtained by the A-A' line is shown in the figure. The upper and lower resonators are provided with wing bridges and protrusions and depressions, and the top electrode of the lower resonator is electrically connected to the bottom electrode of the upper resonator.

[0030] Figure 3B For an exemplary embodiment of the present invention, along Figure 2 A schematic cross-sectional view of a bulk acoustic resonator obtained by the B-B' line in the figure, wherein the upper and lower resonators are provided with wing bridges and protrusions and recesses, and the top electrode of the lower resonator is electrically connected to the bottom electrode of the upper resonator.

[0031] Figure 3C For an exemplary embodiment of the present invention, along Figure 2 A schematic cross-sectional view of a bulk acoustic resonator obtained by the C-C' line, wherein the upper and lower resonators are provided with wing bridges and protrusions and recesses, and the top electrode of the lower resonator is electrically connected to the bottom electrode of the upper resonator.

[0032] Figure 3D For illustrative purposes only Figure 3A The structure relative to Figure 1 A comparison of insertion loss curves for the structures;

[0033] Figure 4-8 For different exemplary embodiments of the present invention, along Figure 2 The schematic cross-sectional view of the bulk acoustic resonator obtained by the A-A' line is shown in the figure. The upper and lower resonators are provided with wing bridges and protrusions and depressions. The top electrode of the lower resonator is electrically connected to the bottom electrode of the upper resonator.

[0034] Figure 9 For yet another exemplary embodiment of the present invention, along Figure 2 The schematic cross-sectional view of the bulk acoustic resonator obtained by the A-A' line is shown in the figure. The non-electrode connection end of the top electrode of the upper and lower resonators is provided with a cantilever, and the top electrode of the lower resonator is electrically connected to the bottom electrode of the upper resonator.

[0035] Figure 10 To provide an exemplary embodiment of the present invention, along Figure 2 The schematic cross-sectional view of the bulk acoustic resonator obtained by the A-A' line is shown in the figure. The non-electrode connection end of the top electrode of the upper and lower resonators is provided with a protrusion and a recess. The top electrode of the lower resonator is electrically connected to the bottom electrode of the upper resonator.

[0036] Figure 11 For yet another exemplary embodiment of the present invention, along Figure 2 The schematic cross-sectional view of the bulk acoustic resonator obtained by the A-A' line is shown in the figure. The upper and lower resonators are provided with wing bridges and protrusions and depressions. The top electrode of the lower resonator is electrically isolated from the bottom electrode of the upper resonator.

[0037] Figure 12 To provide an exemplary embodiment of the present invention, along Figure 2 The schematic cross-sectional view of the bulk acoustic resonator obtained by the A-A' line is shown in the figure. The upper and lower resonators are provided with wing bridges and protrusions and depressions. The top electrode of the lower resonator is electrically isolated from the bottom electrode of the upper resonator.

[0038] Figures 13A-13H An example is shown Figure 3A A schematic diagram illustrating the fabrication process of the structure shown.

[0039] Figure 14A and 14B An example shows the production Figure 7-8 A schematic diagram of the structure of the method shown in the figure;

[0040] Figure 15 A schematic cross-sectional view of a bulk acoustic resonator assembly according to an exemplary embodiment of the present invention. 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] The reference numerals in the drawings of this invention are explained as follows:

[0043] 10: The bottom electrode of the lower resonator has external leads.

[0044] 20: The top electrode of the upper resonator has an external lead.

[0045] S: Substrate, with optional materials including single-crystal silicon, gallium nitride, gallium arsenide, sapphire, quartz, silicon carbide, diamond, etc.

[0046] 101, 201: Acoustic mirrors. Acoustic mirror 103 can be a cavity, or it can be a Bragg reflector layer or other equivalent forms. Acoustic mirror 201 is a cavity, which constitutes an acoustic decoupling layer.

[0047] 102,202: Bottom electrode, materials can be selected from molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or composites or alloys of the above metals, etc.

[0048] 103, 203: Piezoelectric layer, which 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 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.

[0049] 104, 204: Top electrode, whose material can be the same as the bottom electrode. Materials can include molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, or composites or alloys of the above metals. The top and bottom electrodes are generally made of the same material, but they can also be different.

[0050] 105, 205: Cavity between the suspension or top electrode and the piezoelectric layer.

[0051] 106,206: Protruding structure.

[0052] 107,207: Depressed structure.

[0053] Figure 2 This is a schematic top view of a bulk acoustic resonator assembly according to an exemplary embodiment of the present invention. Figure 2 In the diagram, line A-A' corresponds to the cross-section through the non-electrode connection terminals of the top and bottom electrodes of the upper and lower resonators, line B-B' corresponds to the cross-section through the electrode connection terminal of the top electrode of the upper resonator and the non-electrode connection terminal of the bottom electrode of the upper resonator, and line C-C' corresponds to the cross-section through the electrode connection terminal of the top electrode of the lower resonator and the non-electrode connection terminal of the bottom electrode of the lower resonator.

[0054] Figure 3A For an exemplary embodiment of the present invention, along Figure 2 A schematic cross-sectional view of a bulk acoustic resonator obtained by intercepting the A-A' line.

[0055] Although not shown, a process layer can also be disposed on the top electrode of the resonator. This process layer can cover the top electrode and can function as a mass conditioning load or a passivation layer. The passivation layer can be made of a dielectric material, such as silicon dioxide, aluminum nitride, or silicon nitride.

[0056] In addition, Figure 3A In the structure shown, two resonators are formed at the same horizontal position on the substrate S, and the two resonators are spatially different in the vertical direction or in the thickness direction of the substrate.

[0057] As those skilled in the art will understand, three or more resonators may be stacked. Figure 15 This is a schematic cross-sectional view of a bulk acoustic resonator assembly according to an exemplary embodiment of the present invention. Figure 15 As shown, the resonator assembly includes a first resonator, a second resonator, and a third resonator stacked in the thickness direction. An acoustic decoupling layer 201 (a cavity in this embodiment) is provided between the top electrode 104 of the first resonator and the bottom electrode 202 of the second resonator. An acoustic decoupling layer 301 (a cavity in this embodiment) is also provided between the top electrode 204 of the second resonator and the bottom electrode 302 of the third resonator. The acoustic decoupling layer 301 constitutes the acoustic mirror of the third resonator. As will be understood, the assembly structures shown in other embodiments of the invention can also be stacked.

[0058] exist Figure 3AThe structure shown includes two resonators, an upper and a lower one. The effective region of the upper resonator is the overlapping area in the thickness direction of the top electrode 204, the piezoelectric layer 203, the bottom electrode 202, and the cavity 201. The lower resonator is the overlapping area in the thickness direction of the cavity 201, the top electrode 104, the piezoelectric layer 103, the bottom electrode 102, and the acoustic mirror 101.

[0059] Correspondingly, in Figure 15 In the middle, the effective region of the uppermost third resonator is the overlapping region of the top electrode 304, piezoelectric layer 303, bottom electrode 302, and cavity 301 in the thickness direction; the effective region of the middle second resonator is the overlapping region of the cavity 301, top electrode 204, piezoelectric layer 203, bottom electrode 202, and cavity 201 in the thickness direction; and the effective region of the lowermost first resonator is the overlapping region of the cavity 201, top electrode 104, piezoelectric layer 103, bottom electrode 102, and cavity 101 in the thickness direction.

[0060] exist Figure 3A In the structure shown, the upper resonator and the lower resonator are acoustically separated by the cavity 201. That is, the cavity 201 constitutes an acoustic decoupling layer between the upper and lower resonators, thereby completely avoiding the acoustic coupling problem that may be caused by the adjacent stacking of the two resonators.

[0061] Using cavity 201 as an acoustic decoupling layer enables complete acoustic decoupling of the upper and lower resonators, resulting in superior resonator performance. Furthermore, cavity 201 is directly surrounded by the top electrode 104 of the lower resonator and the bottom electrode 202 of the upper resonator (in other embodiments, the structure defining the cavity location also includes the piezoelectric layer of the upper and / or lower resonator), for example... Figures 3A-3C In the case of the structure shown in Figure 11, the overall structure is stable and reliable and the processing technology is simple.

[0062] As those skilled in the art will understand, the cavity 201 disposed between the bottom electrode of the upper resonator and the top electrode of the lower resonator in the thickness direction of the resonator includes not only the case where at least a portion of the upper and lower boundaries of the cavity is defined by the lower surface of the bottom electrode of the upper resonator and the upper surface of the top electrode of the lower resonator, but also the case where a process layer (e.g., a passivation layer) is disposed on the upper surface of the top electrode of the lower resonator, thereby defining at least a portion of the lower boundary of the cavity 201. All of these are within the scope of protection of this invention.

[0063] exist Figure 3A In the structure shown, because multiple resonators are formed at the same horizontal position on the substrate S, and the spatial positions of these resonators differ in the vertical direction or in the thickness direction of the substrate, the area of ​​the filter can be greatly reduced. For example, with the same arrangement of two resonators, the area can be reduced from... Figure 1The area P1 shown is reduced to Figure 3A The area P2 shown is shown.

[0064] like Figure 3A As shown, the bottom electrode 202 of the upper resonator and the top electrode 104 of the lower resonator are electrically connected to each other at the non-electrode connection terminals. When the bottom electrode of the upper resonator is directly connected to the top electrode of the lower resonator, the bottom electrode of the upper resonator and the top electrode of the lower resonator are directly electrically connected, and the length of the connection portion is relatively... Figure 1 The intermediate frequency is shortened, meaning the transmission path is shortened, reducing transmission loss. Furthermore, the electrical signal output passes through a metal with a thickness equal to the sum of the thicknesses of the top electrode of the lower resonator and the bottom electrode of the upper resonator, further reducing transmission loss. By reducing electrical loss, the insertion loss of the final filter is optimized. For example... Figure 3A As shown, the length of the transmission path formed by the bottom electrode of the upper resonator and the top electrode of the lower resonator at the non-connected end of the electrodes is d, which can be less than 5μm.

[0065] Using the structure shown in Figures 3A-3C, the current transmission path to the lower resonator is shortened, for example, to less than 5 μm, reducing transmission loss. This allows for thinner top electrode 104 of the lower resonator and bottom electrode 202 of the upper resonator, facilitating further miniaturization of the resonator. With the bottom electrode of the upper resonator and the top electrode of the lower resonator electrically connected, the circuit transmission path loss to the bottom electrode of the upper resonator and the current transmission path loss to the top electrode of the lower resonator can be reduced, while simultaneously decreasing the electrode film thickness of both the bottom and top electrodes of the upper resonator. Correspondingly, when the resonant frequency of the lower resonator is greater than 0.5 GHz, the thickness of the top electrode 104 is less than... And / or, when the resonant frequency of the upper resonator is greater than 0.5 GHz, the thickness of the bottom electrode 202 is less than In a further embodiment, when the resonant frequency of the lower resonator is greater than 3 GHz, the thickness of the top electrode 104 can be designed to be less than [the required thickness]. And / or, when the resonant frequency of the upper resonator is greater than 3 GHz, the thickness of the bottom electrode 202 of the upper resonator can also be less than [a certain value]. As will be understood, in this invention, the thinning of the electrode thickness refers to the thinning of the portion of the electrode within the effective region of the resonator.

[0066] Figure 3D For illustrative purposes only Figure 3A The structure relative to Figure 1 The insertion loss curves of the structures are compared. Figure 3D shows the insertion loss curves of the 3.5G band using the present invention. Figure 3A The insertion loss curve (solid line) after the structure is compared with that after using Figure 1A comparison of the insertion loss curve (dashed line) of the traditional structure shows that the method using the present invention... Figure 3A After the structure is completed, the insertion loss is increased by approximately 0.1 dB due to the reduction in electrode loss.

[0067] When the bottom electrode of the upper resonator and the top electrode of the lower resonator are electrically connected to each other, Figure 3A In the structure shown, the bottom electrode of the upper resonator and the non-electrode connection terminal of the top electrode of the lower resonator are connected to each other. However, besides... Figure 3A Besides the connection method shown, other connection methods are also possible. For example, the bottom electrode of the upper resonator and the top electrode of the lower resonator may be electrically connected to each other only at some of the non-electrode connection terminals; or, the bottom electrode of the upper resonator and the top electrode of the lower resonator may be electrically connected to each other only at the electrode connection terminals; or, the bottom electrode of the upper resonator and the top electrode of the lower resonator may be electrically connected to each other only at all or some of the non-electrode connection terminals; or, the bottom electrode of the upper resonator and the top electrode of the lower resonator may be electrically connected to each other not only at the electrode connection terminals but also at the non-electrode connection terminals. All of these are within the scope of protection of this invention.

[0068] When the ratio of the maximum effective width of the resonator to the cavity height is large, the upper and lower resonators may come into contact within the cavity due to bending or other reasons. For example, if the cavity height is... When the maximum width of the effective region of the resonator is greater than 100μm, in order to ensure the complete formation of the cavity 201 within the effective regions of the upper and lower resonators, the stress of the lower resonator can be controlled to bend it downward toward the air cavity, and / or the stress of the upper resonator can be controlled to bend it upward toward the air cavity. The top electrode of the lower resonator is concave downward, and / or the bottom electrode of the upper resonator is convex upward.

[0069] Although controlled stress can reduce the probability of the upper and lower resonators coming into contact with each other, when the resonator area is large, a support can be added between the upper and lower resonators in the cavity 201. This support can contact the top or top electrode of the lower resonator, and the height of the support must be less than or equal to the height of the cavity. Equal means that the top of the support contacts the bottom or bottom electrode of the upper resonator. The height of the support is less than the height of the cavity, which means that the top of the support does not contact the upper resonator. When the cavity thickness is reduced locally due to the bending of the resonator, the top of the support will contact the upper resonator and play a supporting role.

[0070] Although controlled stress can reduce the probability of the upper and lower resonators coming into contact with each other, when the resonator area is large, a support can be added between the upper and lower resonators in the cavity 201. This support can contact the top or top electrode of the lower resonator, and the height of the support must be less than or equal to the height of the cavity. Equal means that the top of the support contacts the bottom or bottom electrode of the upper resonator. The height of the support is less than the height of the cavity, which means that the top of the support does not contact the upper resonator. When the cavity thickness is reduced locally due to the bending of the resonator, the top of the support will contact the upper resonator and play a supporting role.

[0071] The resonator mainly utilizes the piezoelectric / inverse piezoelectric effect to convert the elastic energy of longitudinal vibration into the electrical energy of the applied electric field. Energy loss during operation consists of three parts: (1) heat loss from vibration within the piezoelectric layer, (2) electrode loss, and (3) transverse wave dissipation loss. Reducing the first type of loss requires improving the piezoelectric material itself, such as using low-loss single-crystal aluminum nitride. The second type of loss generally only plays a major role at high frequencies (>3GHz) when the electrode thickness is very thin. To reduce transverse wave dissipation loss, such as… Figure 3A As shown, an acoustic boundary structure is provided in the resonator assembly according to the present invention.

[0072] exist Figure 3A In the upper resonator, the top electrode 204 has a recessed structure 207. The resonant frequency of the portion with the recessed structure 207 is higher than the resonant frequency of the effective region of the upper resonator. Therefore, it can suppress transverse wave losses below the resonant frequency of the effective region. The degree of suppression is proportional to the width d207 of this structure. The top electrode of the upper resonator also has a protruding structure 206. The resonant frequency of the portion with the protruding structure 206 is lower than the resonant frequency of the effective region of the upper resonator. Therefore, it can suppress transverse wave losses above the resonant frequency of the effective region. The degree of suppression varies periodically with the width d206 of this protruding structure. The width needs to be appropriately selected. In addition, the acoustic impedance of this portion is different from that of the effective region, thereby reflecting a portion of the transverse wave capability and reducing energy loss. The top electrode 204 of the upper resonator is also provided with a cantilever 205. The cantilever 205 forms a gap structure (which can also be filled with dielectric material) between the top electrode of the upper resonator and the piezoelectric layer. This changes the electric field on the surface of the piezoelectric layer 203, thereby changing the local vibration mode of the piezoelectric layer 203 and suppressing the leakage of transverse wave energy. The degree of suppression varies periodically with the width d205 of the cantilever 205. By appropriately selecting the values ​​of d205, d206, and d207, these three boundary structures can improve the Q value of the upper resonator throughout the entire frequency range.

[0073] The top electrode of the lower resonator is provided with a recessed structure 107, a raised structure 106, and a cantilever 105. The cantilever 105 forms a gap structure between the top electrode of the lower resonator and the piezoelectric layer (this gap can also be filled with dielectric material). The working principle of the recessed structure 107, the raised structure 106, and the cantilever 105 is the same as above, and will not be described again.

[0074] In the embodiments of the present invention, the example given is a raised and recessed portion that includes both a protrusion and a recess. However, as those skilled in the art will understand, the raised and recessed portion may also include only a protrusion or only a recess. Furthermore, in the illustrated embodiment, in the raised and recessed portion that simultaneously provides a protrusion and a recess, the protrusion is located outside the recess; however, the present invention is not limited to this, and the protrusion may also be located inside the recess. All of the above are within the protection scope of the present invention.

[0075] In one embodiment of the invention, the boundary of the cavity 201 is located outside the inner edge of the cantilever 105 in the lateral direction, and for the cantilever 105, in Figure 3A In this context, the lateral distance between the inner edge of the cantilever 105 and the boundary of the acoustic mirror 101 is taken as the width d105 of the cantilever 105, such as... Figure 3A As shown. By appropriately selecting the values ​​of d105, d106, and d107, these three boundary structures can improve the Q value of the lower resonator.

[0076] In this invention, the wing-bridge section refers to a structure having a cantilever and / or a bridge section. Figure 3A In the structure shown, both the top electrodes 104 and 204 are provided with wing bridges.

[0077] Figure 3B For an exemplary embodiment of the present invention, along Figure 2 A schematic cross-sectional view of a bulk acoustic resonator intercepted by the B-B' line. Figure 3B In, with Figure 3A Similarly, the upper and lower resonators also have wing-bridge portions and protruding and recessed portions, and the top electrode 104 of the lower resonator is electrically connected to the bottom electrode 202 of the upper resonator. Figure 3B As can be seen, the electrode connection portion of the top electrode 204 is provided with a bridge portion.

[0078] Figure 3C For an exemplary embodiment of the present invention, along Figure 2 A schematic cross-sectional view of a bulk acoustic resonator intercepted by the C-C' line. Figure 3C In the middle, the upper and lower resonators are provided with wing bridge portions and protruding and recessed portions, and the top electrode 104 of the lower resonator is electrically connected to the bottom electrode 202 of the upper resonator. Figure 3C In the middle, a bridge section is provided at the electrode connection part of the lower resonator.

[0079] exist Figures 3A-3C In the middle, the outer edge of the wing bridge portion 105 of the bottom electrode is located outside the edge of the bottom electrode 102 in the lateral direction. This helps to prevent the formation of a vertical structure of the top electrode 104, piezoelectric layer 103, and bottom electrode 102 outside the effective area of ​​the lower resonator, which would reduce the resonator performance.

[0080] It should be noted that in this invention, the same reference numerals in different embodiments have the same definition or meaning; therefore, the above references are consistent. Figures 3A-3C The descriptions of parameters, components, or structures made herein also apply to the same parameters, components, or structures in subsequent embodiments.

[0081] Figure 4-8 For different exemplary embodiments of the present invention, along Figure 2 The schematic cross-sectional view of the bulk acoustic resonator obtained by the A-A' line is shown in the figure. The upper and lower resonators are provided with wing bridges and protrusions and depressions. The top electrode of the lower resonator is electrically connected to the bottom electrode of the upper resonator.

[0082] like Figure 4 As shown, the non-electrode connection end of the top electrode 104 is provided with a bridge portion 105, while the non-electrode connection end of the top electrode 204 is provided with a cantilever 205. Figure 4 In the illustrated embodiment, the acoustic boundary structure includes a bridge portion 105 disposed in the top electrode 104 and a cantilever 205 disposed in the top electrode 204. For example... Figure 4 As shown, the inner edges of the bridge portion 105 and the cantilever 205 are located inside the boundary of the cavity 201 in the lateral direction.

[0083] For the 105-inch suspension, in Figure 4 In this context, the lateral distance between the inner edge of the cantilever 105 and the boundary of the acoustic mirror 101 is defined as the width d105 of the cantilever 105; for the bridge portion 205, in Figure 4 In this context, the lateral distance between the inner edge of the bridge portion 205 and the boundary of the cavity 201 is taken as the width d205 of the bridge portion 205. Figure 4 In this case, since the outer edge of the bridge portion 205 is outside the boundary of the cavity 201, the width d205 of the bridge portion 205 is the distance from the inner edge of the bridge portion 205 to the boundary of the acoustic mirror 101 in the lateral direction, rather than the actual width of the bridge portion 205.

[0084] like Figure 5As shown, the non-electrode connection end of the top electrode 104 is provided with a protruding structure 106 and a recessed structure 107, while the non-electrode connection end of the top electrode 204 is provided with a protruding structure 206 and a recessed structure 207. In the embodiment shown in FIG. 5, the acoustic boundary structure includes the protruding structure 106, the recessed structure 107, and the cantilever 105 provided at the non-electrode connection end of the top electrode 104, and the bridge portion 205, the protruding structure 206, and the recessed structure 207 at the non-electrode connection end of the top electrode 204.

[0085] like Figure 5 As shown, the outer edges of the protrusions and recesses in the top electrode define the boundaries of the effective region of the corresponding resonator. Figure 5 As shown, the outer edges of the protruding and recessed structures are located inside the boundary of the cavity 201 in the lateral direction. The inner edges of the bridge portion 205 and the cantilever 105 are located inside the boundary of the cavity 201 in the lateral direction.

[0086] For the 105-inch suspension, in Figure 5 In this context, the lateral distance between the inner edge of the cantilever 105 and the boundary of the acoustic mirror 101 is defined as the width d105 of the cantilever 105; for the bridge portion 205, in Figure 5 In this context, the lateral distance between the inner edge of the bridge portion 205 and the boundary of the cavity 201 is taken as the width d205 of the bridge portion 205. Figure 5 In this case, since the outer edge of the bridge portion 205 is outside the boundary of the cavity 201, the width d205 of the bridge portion 205 is the distance between the inner edge of the bridge portion 205 and the boundary of the cavity 201 in the lateral direction, rather than the actual width of the bridge portion 205.

[0087] like Figure 5 As shown, the outer edge of the bridge portion 205 is located outside the boundary of the cavity 201 in the lateral direction. This helps to prevent the formation of a vertical structure consisting of the top electrode 204, the piezoelectric layer 203, and the bottom electrode 202 outside the effective area of ​​the upper resonator, which would affect the performance of the upper resonator.

[0088] Although in the embodiments illustrated above, the recesses, protrusions, and cantilevered wings are all located in the top electrode region, recesses and protrusions can also be formed on the bottom electrode at similar locations. Figure 7 and Figure 8 In the illustrated embodiment, the bottom electrode has a raised and recessed structure.

[0089] like Figure 6 As shown, the non-electrode connection end of the top electrode 104 is provided with a protruding structure 106, a recessed structure 107, and a bridge portion 105, while the non-electrode connection end of the top electrode 204 is provided with a protruding structure 206, a recessed structure 207, and a bridge portion 205. Figure 6In the illustrated embodiment, the acoustic boundary structure includes protrusions and recesses, as well as bridges, disposed in the top electrode.

[0090] like Figure 6 As shown, the outer edges of the protrusions and recesses of the top electrode, or the inner edges of the bridge portion, define the boundaries of the effective region of the corresponding resonator. For example... Figure 6 As shown, the outer edges of the protrusions and recesses are located inside the boundary of the cavity 201 in the lateral direction, and the inner edges of the bridge portions 105 and 205 are located inside the boundary of the cavity 201 in the lateral direction.

[0091] For bridge section 105, in Figure 6 In this context, the lateral distance between the inner edge of the bridge portion 105 and the boundary of the acoustic mirror 101 is defined as the width d105 of the bridge portion 105; for the bridge portion 205, in Figure 6 In this context, the lateral distance between the inner edge of the bridge portion 205 and the boundary of the cavity 201 is taken as the width d205 of the bridge portion 205. Figure 6 In this case, because the outer edge of the bridge portion 205 is outside the boundary of the cavity 201, the width d205 of the bridge portion 205 is the distance between the inner edge of the cantilever 205 and the boundary of the cavity 201 in the lateral direction, rather than the actual width of the bridge portion 205.

[0092] like Figure 7 As shown, the non-electrode connection end of the top electrode 104 is provided with a protruding structure 106 and a recessed structure 107, as well as a bridge portion 105, while the non-electrode connection end of the top electrode 204 is provided with a protruding structure 206 and a recessed structure 207, as well as a cantilever 205; in addition, the bottom electrode 202 of the upper resonator is provided with a protruding structure 208 and a recessed structure 209. Figure 7 In the illustrated embodiment, the acoustic boundary structure includes protrusions and recesses, bridges and cantilevered structures disposed at the non-electrode connection ends of the top electrodes 104 and 204, as well as protrusions and recesses disposed at the non-electrode connection ends of the bottom electrode 202 of the upper resonator.

[0093] like Figure 7 As shown, the outer edges of the protrusions and recesses of the top electrode, or the inner edges of the bridge or cantilever, define the boundaries of the effective region of the corresponding resonator. For example... Figure 7 As shown, the outer edges of the protrusions and depressions of the top electrode are located inside the boundary of the cavity 201 in the lateral direction, and the inner edges of the bridge or cantilever 105 and 205 are located inside the boundary of the cavity 201 in the lateral direction.

[0094] For bridge section 105, in Figure 7 In this context, the lateral distance between the inner edge of the bridge portion 105 and the boundary of the acoustic mirror 101 is defined as the width d105 of the bridge portion 105; for the cantilever 205, in Figure 7 In this context, the lateral distance between the inner edge of the cantilever 205 and the boundary of the cavity 201 is taken as the width d205 of the cantilever 205. Figure 7 In this case, since the outer edge of the cantilever 205 is inside the boundary of the cavity 201, the width d205 of the bridge portion 205 is the actual width of the cantilever 205.

[0095] Figure 8 The structure shown is Figure 7 The difference in the structure shown is that, Figure 8 In the middle, the bottom electrode 102 of the lower resonator is provided with a protruding structure 108 and a recessed structure 109. Figure 8 In order to increase the structural symmetry of the top and bottom electrodes of the lower resonator, the outer edge of the protrusion structure 108 of the bottom electrode 102 is flush with the outer edge of the protrusion structure 108 of the top electrode 104, and the inner edge of the recessed structure 109 of the bottom electrode 102 is flush with the inner edge of the recessed structure 107 of the top electrode 104.

[0096] Furthermore, although not shown in this invention, when both the bottom electrode and the top electrode of a resonator are provided with protruding and recessed structures, in the lateral direction, the recessed structure of one electrode can be inside the recessed structure of the other electrode, and the protruding structure of one electrode can be inside the protruding structure of the other electrode.

[0097] exist Figure 8 In the above reference, the widths d105 and d205 are used. Figure 3A-7 Definition or explanation.

[0098] Figure 9 For yet another exemplary embodiment of the present invention, along Figure 2 A schematic cross-sectional view of a bulk acoustic resonator intercepted by line A-A'. Figure 9 In the middle, the non-electrode connection terminals of the top electrodes of the upper and lower resonators are respectively provided with cantilever blades 105 and 205, and the top electrode of the lower resonator is electrically connected to the bottom electrode of the upper resonator. Figure 9 In the middle, the inner edges of the cantilever 105 and 205 are located inside the boundary of the cavity 201 in the lateral direction.

[0099] Figure 10 To provide an exemplary embodiment of the present invention, along Figure 2 The diagram shows a schematic cross-sectional view of a bulk acoustic resonator taken along line A-A'. The non-electrode connection ends of the top electrodes of the upper and lower resonators are respectively provided with protruding structures 106 and 206, and recessed structures 107 and 207. The top electrode of the lower resonator is electrically connected to the bottom electrode of the upper resonator. Figure 10 As shown, the outer edges of the protrusions and recesses in the top electrode define the boundaries of the effective region of the corresponding resonator. Figure 10 As shown, the outer edges of the protrusions and recesses of the top electrode are located inside the boundary of the cavity 201 in the lateral direction.

[0100] In the above Figures 3A-10 In the illustrated embodiment, the bottom electrode 202 of the upper resonator and the top electrode 104 of the lower resonator are electrically connected to each other. However, the present invention is not limited thereto, and the bottom electrode 202 of the upper resonator and the top electrode 104 of the lower resonator can also be electrically isolated from each other.

[0101] Figure 11 For yet another exemplary embodiment of the present invention, along Figure 2 A schematic cross-sectional view of a bulk acoustic resonator intercepted by line A-A'. Figure 11 In the upper resonator, at least a portion of the non-electrode connection end of the bottom electrode 202 is disposed on the upper surface of the piezoelectric layer 103 in the circumferential direction, and the at least a portion of the end is located outside the acoustic boundary structure (wing bridge and protrusion / recess) of the top electrode 104 in the horizontal direction. Therefore, Figure 11 In the middle, the top electrode 104 of the lower resonator is electrically isolated from the bottom electrode 102 of the upper resonator.

[0102] Figure 12 To provide an exemplary embodiment of the present invention, along Figure 2 A schematic cross-sectional view of a bulk acoustic resonator intercepted by line A-A', showing that the upper and lower resonators have acoustic boundary structures including a wing bridge and protruding and recessed portions. Figure 12 In the middle, a portion of the non-electrode connection terminal of the bottom electrode 202 of the upper resonator along the circumferential direction (see, for example, see...) Figure 12 The left end of the bottom electrode 202 is disposed on the upper surface of the piezoelectric layer 103, and the other part of the non-electrode connection end of the bottom electrode 202 along the circumferential direction (e.g., the left end) is disposed on the upper surface of the piezoelectric layer 103. Figure 12 The right end of the lower resonator is located inside the boundary of the cavity 201 in the horizontal direction, and the top electrode 104 of the lower resonator is electrically isolated from the bottom electrode 202 of the upper resonator.

[0103] exist Figure 9-12 In the text, the descriptions of 105-107 and 205-207, as well as d105, d106, and d107, and d205, d206, and d207, adopt the above reference appendix. Figure 3A-7 Definition or explanation.

[0104] In this invention, such as Figures 3A-3C As shown in Figure 4-12, the effective region of the upper resonator is A2, and the effective region of the lower resonator is A1. In the embodiment shown, the effective regions A1 and A2 are both located inside the boundary of the cavity 201 in the lateral direction.

[0105] exist Figures 3A-3C In 4-8 and 10-12, the regions between the inner edges of the raised and recessed structures are regions I1 and I2 for the lower resonator and the upper resonator, respectively.

[0106] In optional embodiments, such as Figures 3A-3C As shown in Figures 4-8 and 10-12, the boundary of effective region A2 is inside the boundary of effective region A1, and the boundary of region I2 is inside the boundary of region I1. If the boundary of effective region A2 extends beyond the boundary of effective region A1 in the lateral direction, or the boundary of region I2 extends beyond the boundary of region I1 in the lateral direction, the lateral acoustic loss of the upper resonator will increase, and the Q value of the upper resonator will decrease. Therefore, in a further embodiment, the present invention restricts the boundaries of effective region A2 and region I2 to the inside of the boundaries of effective region A1 and region I1, respectively, which helps to further improve the Q value of the upper resonator.

[0107] The following reference Figure 13A-13G Exemplary Description Figure 3A The fabrication process of the structure shown.

[0108] Step 1: As Figure 13A As shown, the lower resonator is fabricated using a conventional FBAR process, including the fabrication of a first sacrificial material layer corresponding to the acoustic mirror 101, a bottom electrode 102, and a piezoelectric layer 103. Then, a second sacrificial material layer corresponding to the gap defined by the cantilever 105 is fabricated on the piezoelectric layer 103. The second sacrificial material layer can be made of the same material as the first sacrificial material layer, such as phosphosilicate glass. Both the first and second sacrificial material layers are removed together in subsequent steps. Figure 13A-13G In the diagram, passivation layers, frequency modulation layers, and other films that are not closely related to the concept of this patent are not shown.

[0109] Step 2: As Figure 13B As shown, in step 1, an electrode metal layer for forming the top electrode 104 of the lower resonator is deposited on the structure by sputtering or evaporation. Then, the electrode metal layer corresponding to the top electrode 104 is etched by photolithography and etching processes to pattern the top electrode metal layer for forming the top electrode 104.

[0110] Step 3: On the structure of Step 2, a protrusion structure 106 is deposited on the metal layer of the top electrode 104 by means of a lift-off process, and a recessed structure 107 is fabricated by depositing top electrode metal material at a location other than the recessed structure 107, finally forming a structure as shown in the figure. Figure 13C The top electrode 104 is shown in the diagram.

[0111] Step 4: Deposit the third sacrificial material layer to form cavity 201. The material of the third sacrificial material layer can be PSG (phosphosilicate glass), amorphous silicon, BSG (borosilicate glass), BPSG (borophosphosilicate glass), USG (US silicate glass), etc. To improve the quality of the film layer on the subsequent resonator, the surface of the deposited third sacrificial material layer can be planarized using CMP (chemical mechanical polishing) to obtain the desired result. Figure 13D The structure shown. The third sacrificial material layer will eventually be removed to form cavity 201, which acoustically isolates the upper and lower resonators.

[0112] Step 5: Fabricate the bottom electrode 202 and piezoelectric layer 203 of the resonator on the structure formed in step 4. Then, fabricate a fourth sacrificial material layer on the piezoelectric layer 203 corresponding to the gap defined by the cantilever 205, to form a structure as shown in the figure. Figure 13E In the structure shown, the fourth sacrificial material layer can be the same material as the first sacrificial material layer, such as phosphosilicate glass, etc. The first sacrificial material layer and the fourth sacrificial material layer are removed together in subsequent steps.

[0113] Step 6: Fabricate the top electrode 204 of the resonator on the structure formed in step 5, forming as shown in the figure. Figure 13F The structure shown.

[0114] Step 7: Deposit the protruding structure 206 using a lift-off process or similar method, and fabricate the recessed structure 207 by depositing top electrode metal material outside the recessed structure 207, ultimately forming a structure as shown in the image. Figure 13G The top electrode 104 is shown in the diagram.

[0115] Step 8: Remove all sacrificial material layers to form a structure like... Figure 3A The structure shown.

[0116] The above Figure 3A The fabrication process of the structure shown can also be applied to Figure 3B-3C The structure shown in 4-6 only requires a slight change in the shape of the top electrode when the suspension is replaced with a bridge section.

[0117] for Figure 7 The fabrication process of the structure shown is the same as described above, with steps 1-4 preceding each step. Then, as shown in Figure 14A, protrusions (corresponding to recessed structure 209) and recessed structures (corresponding to protrusions 208) are fabricated on the third sacrificial material layer corresponding to cavity 201. Then, in... Figure 14A A bottom electrode metal layer for the bottom electrode 202 is deposited on the structure, and the bottom electrode metal layer is planarized using a CMP process to form a structure as shown in the figure. Figure 14B The structure is shown. Subsequent steps are similar to steps 5-8 above.

[0118] for Figure 8 The fabrication process of the structure shown is related to... Figure 7 The fabrication process of the structure shown is similar, except that a raised structure 108 and a recessed structure 109 are fabricated on the lower surface of the bottom electrode of the lower resonator, which is similar to... Figures 14A-14B The protrusions corresponding to the recessed structure 209 and the recessed structure corresponding to the protruding structure 208 are formed in the preceding step 1. This can be achieved by forming the recesses corresponding to the protruding structure 108 and the protrusions corresponding to the recessed structure 109 during the formation of the first sacrificial material layer corresponding to the acoustic mirror 101. Other steps are consistent with the manufacturing process. Figure 7 The steps for the structure shown are the same.

[0119] for Figure 9 The fabrication process of the structure shown can be obtained by omitting steps 3 and 7 above.

[0120] for Figure 10 The fabrication process of the structure shown can be obtained by omitting steps 1 and 5.

[0121] 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.

[0122] In this invention, "upper" and "lower" are relative to the bottom surface of the resonator's 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.

[0123] In this invention, "inner" and "outer" refer to the center of the effective region of the resonator (i.e., the center of the effective region) in the lateral or radial direction. The side or end of a component closer to the center of the effective region is called the inner side or inner end, while the 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.

[0124] As those skilled in the art will understand, the bulk acoustic resonator according to the present invention can be used to form filters or electronic devices. These electronic devices include, but are not limited to, intermediate products such as RF front-ends and filtering / amplifying modules, as well as terminal products such as mobile phones, Wi-Fi devices, and drones.

[0125] Based on the above, the present invention proposes the following technical solution:

[0126] 1. A bulk acoustic resonator assembly, comprising:

[0127] Base;

[0128] At least two resonators, which are bulk acoustic wave resonators, are stacked on one side of a substrate in the thickness direction of the substrate. The at least two resonators include a first resonator and a second resonator, with the second resonator above the first resonator. The first resonator has a first top electrode, a first piezoelectric layer, a first bottom electrode, and a first acoustic mirror. The second resonator has a second top electrode, a second piezoelectric layer, a second bottom electrode, and a second acoustic mirror.

[0129] in:

[0130] An acoustic decoupling layer is provided between the first top electrode and the second bottom electrode, and the acoustic decoupling layer serves as the second acoustic mirror;

[0131] At least one electrode has an acoustic boundary structure along the boundary of the effective region of the corresponding resonator.

[0132] 2. The component according to 1, wherein:

[0133] The acoustic boundary structure includes a wing bridge section.

[0134] 3. The component according to 2, wherein:

[0135] The first top electrode or the first bottom electrode is provided with a first wing bridge portion, and / or the second top electrode or the second bottom electrode is provided with a second wing bridge portion.

[0136] 4. The component according to 3, wherein:

[0137] The inner edge of the wing bridge is located inside the boundary of the acoustic decoupling layer in the horizontal direction.

[0138] 5. The component according to 4, wherein:

[0139] The first top electrode is provided with a first wing bridge portion, and the second top electrode is provided with a second wing bridge portion;

[0140] The inner edge of one of the first and second wing bridge sections is located horizontally outside the inner edge of the other wing bridge section.

[0141] 6. The component according to 4, wherein:

[0142] The inner edge of the first wing bridge is located inside the boundary of the first acoustic mirror in the horizontal direction.

[0143] 7. The component according to 6, wherein:

[0144] The non-electrode connection end of the first bottom electrode is located outside the boundary of the acoustic mirror; and

[0145] The outer edge of the first wing bridge is located outside the non-electrode connection end of the first bottom electrode in the horizontal direction.

[0146] 8. The component according to 4, wherein:

[0147] The wing bridge portion includes a bridge portion disposed at the non-electrode connection end of the second top electrode;

[0148] The inner edge of the bridge portion is located inside the boundary of the acoustic decoupling layer in the horizontal direction, and the outer edge of the bridge portion is located outside the boundary of the acoustic decoupling layer in the horizontal direction.

[0149] 9. The component according to any one of 1-8, wherein:

[0150] The acoustic boundary structure includes raised and recessed portions, which include raised portions and / or recessed portions.

[0151] 10. The component according to 9, wherein:

[0152] The first top electrode or the first bottom electrode is provided with a first protrusion and / or a first depression, and / or the second top electrode or the second bottom electrode is provided with a second protrusion and / or a second depression.

[0153] 11. The component according to 8, wherein:

[0154] The outer edge of the protrusion and recess defines the boundary of the effective region of the corresponding resonator.

[0155] 12. The component according to 9, wherein:

[0156] The inner edge of the first protrusion is located outside the inner edge of the second protrusion in the horizontal direction; and / or

[0157] The inner edge of the first depression is located outside the inner edge of the second depression in the horizontal direction.

[0158] 13. The component according to 10, wherein:

[0159] The inner edge of the first protrusion is located outside the inner edge of the second protrusion in the horizontal direction; and / or

[0160] The inner edge of the first depression is located outside the inner edge of the second depression in the horizontal direction.

[0161] 13. The component according to 9, wherein:

[0162] The outer edge of the protrusion and recess is located inside the boundary of the acoustic decoupling layer in the horizontal direction.

[0163] 14. The component according to any one of 1-13, wherein:

[0164] The first top electrode and the second bottom electrode are electrically connected to each other.

[0165] 15. The component according to 14, wherein:

[0166] The acoustic boundary structure includes a first wing bridge portion disposed at the electrode non-connection end of the first top electrode;

[0167] The second bottom electrode is electrically connected to the first top electrode at the first wing bridge portion.

[0168] 16. The component according to any one of 1-13, wherein:

[0169] The first top electrode and the second bottom electrode are electrically isolated from each other.

[0170] 17. The component according to 16, wherein:

[0171] The acoustic boundary structure includes a first wing bridge portion disposed at the electrode non-connection end of the first top electrode;

[0172] At least a portion of the non-electrode connection end of the second bottom electrode is disposed on the upper surface of the first piezoelectric layer in the circumferential direction, and the at least a portion of the end is located outside the first wing bridge portion in the horizontal direction.

[0173] 18. The component according to 17, wherein:

[0174] A portion of the non-electrode connection end of the second bottom electrode is disposed on the upper surface of the first piezoelectric layer in the circumferential direction, and another portion of the non-electrode connection end of the second bottom electrode is located inside the boundary of the acoustic decoupling layer in the horizontal direction.

[0175] 19. The component according to any one of 1-18, wherein:

[0176] The first resonator has a first effective region, and the second resonator has a second effective region. The boundary of the first effective region is located outside the boundary of the second effective region in the horizontal direction.

[0177] 20. A bulk acoustic resonator assembly, comprising:

[0178] At least two resonators are stacked adjacent to each other from bottom to top in the thickness direction of the component. The at least two resonators are bulk acoustic resonators, and the at least two resonators include a first resonator and a second resonator, wherein:

[0179] An acoustic decoupling layer is disposed between the top electrode of the first resonator and the bottom electrode of the second resonator, and the acoustic decoupling layer serves as an acoustic mirror for the second resonator; and

[0180] At least one electrode has an acoustic boundary structure along the boundary of the effective region of the corresponding resonator.

[0181] 21. The component according to 1 or 20, wherein:

[0182] The at least two resonators include a first resonator, a second resonator, and a third resonator stacked in the thickness direction;

[0183] There is a first acoustic decoupling layer between the top electrode of the first resonator and the bottom electrode of the second resonator, and a second acoustic decoupling layer between the top electrode of the second resonator and the bottom electrode of the third resonator. The second acoustic decoupling layer constitutes the acoustic mirror of the third resonator.

[0184] 22. The component according to 21, wherein:

[0185] The boundary of the second acoustic decoupling layer is located outside the boundary of the first acoustic decoupling layer in the horizontal direction.

[0186] 23. A method for manufacturing a bulk acoustic resonator assembly, comprising:

[0187] Step 1: Form a first structure for a first bulk acoustic resonator on the surface of a substrate, the first bulk acoustic resonator including a first acoustic mirror, a first bottom electrode, a first piezoelectric layer, and a first top electrode;

[0188] Step 2: Apply a patterned sacrificial material layer to the first structure formed in Step 1;

[0189] Step 3: Form a second structure for a second bulk acoustic resonator on the structure of step 2. The second bulk acoustic resonator includes a second acoustic mirror, a second bottom electrode, a second piezoelectric layer, and a second top electrode. The sacrificial material layer is located between the first top electrode and the second bottom electrode in the thickness direction of the substrate.

[0190] Step 4: Release the sacrificial material layer to form a cavity, which constitutes the second acoustic mirror of the second bulk acoustic resonator.

[0191] in:

[0192] At least one of the first top electrode, the second top electrode, the first bottom electrode, and the second bottom electrode has an acoustic boundary structure disposed along the effective region of the corresponding volume acoustic resonator.

[0193] 24. A filter comprising a bulk acoustic resonator assembly according to any one of 1-22.

[0194] 25. An electronic device comprising the filter according to claim 24 or the bulk acoustic resonator assembly according to any one of claims 1-22.

[0195] 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 assembly, comprising: Base; At least two resonators, which are bulk acoustic wave resonators, are stacked on one side of a substrate in the thickness direction of the substrate. The at least two resonators include a first resonator and a second resonator, with the second resonator above the first resonator. The first resonator has a first top electrode, a first piezoelectric layer, a first bottom electrode, and a first acoustic mirror. The second resonator has a second top electrode, a second piezoelectric layer, a second bottom electrode, and a second acoustic mirror. in: An acoustic decoupling layer in the form of a cavity is provided between the first top electrode and the second bottom electrode, and the acoustic decoupling layer serves as the second acoustic mirror; At least one electrode is provided with an acoustic boundary structure along the boundary of the effective region of the corresponding resonator; The effective regions of the first resonator and the second resonator are arranged opposite each other in the thickness direction and located on both sides of the cavity.

2. The component according to claim 1, wherein: The acoustic boundary structure includes a wing bridge section.

3. The component according to claim 2, wherein: The first top electrode or the first bottom electrode is provided with a first wing bridge portion, and / or the second top electrode or the second bottom electrode is provided with a second wing bridge portion.

4. The component according to claim 3, wherein: The inner edge of the wing bridge is located inside the boundary of the acoustic decoupling layer in the horizontal direction.

5. The component according to claim 4, wherein: The inner edge of the first wing bridge is located inside the boundary of the first acoustic mirror in the horizontal direction.

6. The component according to claim 5, wherein: The non-electrode connection end of the first bottom electrode is located outside the boundary of the acoustic mirror; and The outer edge of the first wing bridge is located outside the non-electrode connection end of the first bottom electrode in the horizontal direction.

7. The component according to claim 4, wherein: The wing bridge portion includes a bridge portion disposed at the non-electrode connection end of the second top electrode; The inner edge of the bridge portion is located inside the boundary of the acoustic decoupling layer in the horizontal direction, and the outer edge of the bridge portion is located outside the boundary of the acoustic decoupling layer in the horizontal direction.

8. The component according to any one of claims 1-7, wherein: The acoustic boundary structure includes raised and recessed portions, which include raised portions and / or recessed portions.

9. The component according to claim 8, wherein: The first top electrode or the first bottom electrode is provided with a first protrusion and / or a first depression, and / or the second top electrode or the second bottom electrode is provided with a second protrusion and / or a second depression.

10. The component of claim 9, wherein: The outer edge of the protrusion and recess defines the boundary of the effective region of the corresponding resonator.

11. The component according to claim 9, wherein: The inner edge of the first protrusion is located outside the inner edge of the second protrusion in the horizontal direction; and / or The inner edge of the first depression is located outside the inner edge of the second depression in the horizontal direction.

12. The component of claim 8, wherein: The outer edge of the protrusion and recess is located inside the boundary of the acoustic decoupling layer in the horizontal direction.

13. The component according to any one of claims 1-7, 9-12, wherein: The first top electrode and the second bottom electrode are electrically connected to each other.

14. The component of claim 13, wherein: The acoustic boundary structure includes a first wing bridge portion disposed at the electrode non-connection end of the first top electrode; The second bottom electrode is electrically connected to the first top electrode at the first wing bridge portion.

15. The component according to any one of claims 1-7, 9-12, wherein: The first top electrode and the second bottom electrode are electrically isolated from each other.

16. The component of claim 15, wherein: The acoustic boundary structure includes a first wing bridge portion disposed at the electrode non-connection end of the first top electrode; At least a portion of the non-electrode connection end of the second bottom electrode is disposed on the upper surface of the first piezoelectric layer in the circumferential direction, and the at least a portion of the end is located outside the first wing bridge portion in the horizontal direction.

17. The component of claim 16, wherein: A portion of the non-electrode connection end of the second bottom electrode is disposed on the upper surface of the first piezoelectric layer in the circumferential direction, and another portion of the non-electrode connection end of the second bottom electrode is located inside the boundary of the acoustic decoupling layer in the horizontal direction.

18. The component according to any one of claims 1-7, 9-12, 14, 16, and 17, wherein: The first resonator has a first effective region, and the second resonator has a second effective region. The boundary of the first effective region is located outside the boundary of the second effective region in the horizontal direction.

19. A bulk acoustic resonator assembly, comprising: At least two resonators are stacked adjacent to each other from bottom to top in the thickness direction of the component. The at least two resonators are bulk acoustic resonators, and the at least two resonators include a first resonator and a second resonator, wherein: An acoustic decoupling layer in the form of a cavity is disposed between the top electrode of the first resonator and the bottom electrode of the second resonator, and the acoustic decoupling layer serves as an acoustic mirror for the second resonator; and At least one electrode is provided with an acoustic boundary structure along the boundary of the effective region of the corresponding resonator; The effective regions of the first resonator and the second resonator are arranged opposite each other in the thickness direction and located on both sides of the cavity.

20. The component according to claim 1 or 19, wherein: The at least two resonators include a first resonator, a second resonator, and a third resonator stacked in the thickness direction; A first acoustic decoupling layer exists between the top electrode of the first resonator and the bottom electrode of the second resonator. There is a second acoustic decoupling layer between the top electrode and the bottom electrode of the third resonator, and the second acoustic decoupling layer constitutes the acoustic mirror of the third resonator.

21. The component of claim 20, wherein: The boundary of the second acoustic decoupling layer is located outside the boundary of the first acoustic decoupling layer in the horizontal direction.

22. A method for manufacturing a bulk acoustic resonator assembly, comprising: Step 1: Form a first structure for a first bulk acoustic resonator on the surface of a substrate, the first bulk acoustic resonator including a first acoustic mirror, a first bottom electrode, a first piezoelectric layer, and a first top electrode; Step 2: Apply a patterned sacrificial material layer to the first structure formed in Step 1; Step 3: Form a second structure for a second bulk acoustic resonator on the structure of step 2. The second bulk acoustic resonator includes a second acoustic mirror, a second bottom electrode, a second piezoelectric layer, and a second top electrode. The sacrificial material layer is located between the first top electrode and the second bottom electrode in the thickness direction of the substrate. Step 4: Release the sacrificial material layer to form a cavity, which constitutes the second acoustic mirror of the second bulk acoustic resonator. in: At least one of the first top electrode, the second top electrode, the first bottom electrode, and the second bottom electrode has an acoustic boundary structure disposed along the effective region of the corresponding bulk acoustic resonator; The effective regions of the first bulk acoustic resonator and the second bulk acoustic resonator are arranged opposite each other in the thickness direction and located on both sides of the cavity.

23. A filter comprising a bulk acoustic resonator assembly according to any one of claims 1-21.

24. An electronic device comprising the filter of claim 23 or the bulk acoustic resonator assembly of any one of claims 1-21.

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