Acoustic wave device and method of manufacturing the same

Abstract

The application discloses an acoustic wave device and a manufacturing method thereof. The acoustic wave device comprises at least two regions, at least one of which is provided with a first resonator, and at least one region adjacent to the region where the first resonator is located is provided with a second resonator. The first resonator comprises a first piezoelectric structure, the second resonator comprises a reflection structure and a second piezoelectric structure, the reflection structure is located between the first piezoelectric structure and the second piezoelectric structure, and the stacking direction of the first piezoelectric structure is perpendicular to the stacking direction of the second piezoelectric structure. The technical scheme provided by the application prevents the problem of transverse acoustic energy leakage existing in the thin film bulk acoustic resonator adjacent thereto by adopting the thin film bulk acoustic resonator comprising the reflection structure and the piezoelectric structure, improves the quality factor of the acoustic wave device, and also improves the utilization rate of wafer unit area.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to an acoustic wave device and its manufacturing method. Background Technology

[0002] In wireless communication technology, radio frequency (RF) filters are used to filter specific frequency signals and reduce signal interference between different frequency bands. With the increasing development of 5G communication technology, the requirements for data transmission rates are becoming higher and higher. As a front-end module, RF filters play a crucial role in RF systems, filtering out out-of-band interference and noise to meet the signal-to-noise ratio requirements of RF systems.

[0003] Film bulk acoustic resonators (FBARs) offer advantages such as small size, light weight, low insertion loss, and high quality factor. However, in practical applications, FBARs cannot operate exclusively in longitudinal wave mode; some acoustic energy may leak into the transverse direction, affecting the resonator's Q value (i.e., quality factor). Therefore, preventing transverse acoustic energy leakage in FBARs is a crucial issue that urgently needs to be addressed. Summary of the Invention

[0004] In view of the above-mentioned defects or deficiencies in the prior art, it is desirable to provide an acoustic wave device and its manufacturing method to solve the problem of lateral acoustic energy leakage in existing FBARs.

[0005] In a first aspect, this application provides an acoustic wave device comprising at least two regions, wherein at least one of the at least two regions is provided with a first resonator, and at least one region adjacent to the region where the first resonator is located is provided with a second resonator. The first resonator includes a first piezoelectric structure, and the second resonator includes a reflective structure and a second piezoelectric structure. The reflective structure is located between the first piezoelectric structure and the second piezoelectric structure, and the stacking direction of the first piezoelectric structure is perpendicular to the stacking direction of the second piezoelectric structure.

[0006] Optionally, the first resonator and the second resonator are thin-film bulk acoustic resonators.

[0007] Optionally, at least two regions include a first region and a second region, wherein the first region is provided with an air-gap type thin-film bulk acoustic resonator and the second region is provided with a solid-state assembled type thin-film bulk acoustic resonator.

[0008] Optionally, at least two regions include a first region, a second region, and a third region, wherein the first region is adjacent to the second region, and the second region is adjacent to the third region;

[0009] Both the first and third regions are equipped with air-gap type thin-film bulk acoustic resonators, and the second region is equipped with a solid-state assembled type thin-film bulk acoustic resonator; or,

[0010] Both the first region and the third region are provided with solid-state assembled resonators, and the second region is provided with an air-gap type thin-film bulk acoustic resonator.

[0011] Optionally, at least two regions include at least four regions, which are sequentially adjacent to each other. The first and last regions are provided with the air-gap type thin-film bulk acoustic resonator, and the other regions, excluding the first and last regions, are provided with solid-state assembled type thin-film bulk acoustic resonators.

[0012] Optionally, reflective structures are provided on both sides of the second piezoelectric structure.

[0013] Optionally, the reflective structure includes at least two reflective layers, and the stacking direction of the at least two reflective layers is the same as the stacking direction of the second piezoelectric structure.

[0014] Optionally, the reflective structure is a through hole, and the opening direction of the through hole is the same as the stacking direction of the first piezoelectric structure.

[0015] Optionally, the acoustic device includes a substrate and at least two cavities formed on the substrate, each cavity corresponding to one of the regions;

[0016] The first piezoelectric structure is disposed above at least one of the at least two cavities, the second piezoelectric structure is disposed above the cavity adjacent to the cavity where the first piezoelectric structure is disposed, and the orthographic projection of the second piezoelectric structure on the substrate falls within the cavity adjacent to the cavity where the first piezoelectric structure is disposed.

[0017] Optionally, the first piezoelectric structure includes a first bottom electrode, a first piezoelectric layer, and a first top electrode stacked sequentially from the substrate side;

[0018] The reflective structure includes a first reflective layer and a second reflective layer alternately stacked along a direction perpendicular to the stacking direction of the first piezoelectric structure; or, the reflective structure includes a through-hole extending along a direction perpendicular to the stacking direction of the first piezoelectric structure, with the substrate located below the through-hole.

[0019] The second piezoelectric structure includes a second bottom electrode, a second piezoelectric layer, and a second top electrode, which are sequentially stacked along a direction perpendicular to the stacking direction of the first piezoelectric structure.

[0020] Optionally, the acoustic device further includes an electrode connection line disposed above the reflective structure and the second piezoelectric structure, the electrode connection line being connected to the first top electrode and the second bottom electrode.

[0021] Optionally, the acoustic device further includes a pad disposed above the substrate, the pad being connected to the first resonator or the second resonator for leading out the electrical signal of the first resonator or the second resonator.

[0022] Secondly, this application also provides a method for manufacturing an acoustic wave device, the method comprising:

[0023] Provide a substrate;

[0024] A first piezoelectric structure is formed on the substrate to fabricate a first resonator;

[0025] A reflective structure and a second piezoelectric structure are formed above the substrate to fabricate a second resonator;

[0026] The reflective structure is located between the first piezoelectric structure and the second piezoelectric structure, and the stacking direction of the first piezoelectric structure is perpendicular to the stacking direction of the second piezoelectric structure.

[0027] Optionally, a reflective structure and a second piezoelectric structure are formed above the substrate to fabricate a second resonator, including:

[0028] A first acoustic impedance material is filled over the substrate to form a first material layer;

[0029] The first material layer is processed to form a reflective structure;

[0030] After the reflective structure is formed, the remaining first material layer is processed to form the second piezoelectric structure.

[0031] Optionally, the first material layer is processed to form a reflective structure, including:

[0032] The first patterned region of the first material layer is patterned to obtain at least one first through-hole, which is used as a reflective structure; or,

[0033] The first patterned region of the first material layer is patterned to obtain at least one first through hole; the first material layer adjacent to the first through hole in the first patterned region is used as the first reflective layer, and a second acoustic impedance material is deposited in the first through hole to form a second reflective layer. The first reflective layer and the second reflective layer are alternately arranged to form a reflective structure. The first patterned region refers to the region in the first material layer used to form a reflective structure.

[0034] Optionally, after forming the reflective structure, the remaining first material layer is processed to form a second piezoelectric structure, including:

[0035] The second patterned region of the first material layer is patterned to obtain the second through hole and the third through hole. The second patterned region refers to the region in the first material layer used to form the second piezoelectric structure.

[0036] Metallic material is deposited in the second and third through holes to form a second bottom electrode and a second top electrode;

[0037] After forming the second bottom electrode and the second top electrode, the first material layer between the second bottom electrode and the second top electrode is patterned to obtain the fourth through hole;

[0038] A piezoelectric material is deposited within the fourth through-hole to form the second piezoelectric layer.

[0039] Optionally, after forming the second piezoelectric structure, the fabrication method further includes:

[0040] The end of the second bottom electrode or the second top electrode away from the substrate is etched to form a notch, and insulating material is deposited in the notch;

[0041] Metallic material is deposited above the first piezoelectric structure, the reflective structure, and the second piezoelectric structure to form an electrode connection line, which is used to connect the first top electrode to the second top electrode or the second bottom electrode.

[0042] A pad is formed on the substrate, which is connected to either the first resonator or the second resonator.

[0043] The beneficial effects of the technical solution provided in this application are as follows: The acoustic wave device provided in this application includes at least two regions, at least one of which is provided with a first resonator, and at least one region adjacent to the region where the first resonator is located is provided with a second resonator. The first resonator includes a first piezoelectric structure, and the second resonator includes a reflective structure and a second piezoelectric structure. The reflective structure is located between the first and second piezoelectric structures, and the stacking direction of the first piezoelectric structure is perpendicular to the stacking direction of the second piezoelectric structure. By employing a thin-film bulk acoustic wave resonator that includes a reflective structure and a piezoelectric structure, this solution can prevent the acoustic energy of adjacent thin-film bulk acoustic wave resonators from leaking out of the effective area in the lateral direction, thereby improving the quality factor of the acoustic wave device. The piezoelectric structures of adjacent thin-film bulk acoustic wave resonators are designed to be perpendicular to each other, which can reduce the size of the thin-film bulk acoustic wave resonator in the horizontal direction, allowing more acoustic wave devices or resonator components to be fabricated within a limited area, thereby effectively improving the wafer unit area utilization rate. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 This is a schematic diagram of the cross-sectional structure of an acoustic wave device provided in this application;

[0046] Figure 2 This is a top view of an acoustic wave device provided in this application;

[0047] Figure 3 This is a schematic diagram of the cross-sectional structure of another acoustic wave device provided in this application;

[0048] Figure 4 This is a top view of yet another acoustic wave device provided in this application;

[0049] Figure 5 This is an equivalent circuit diagram of an acoustic wave device provided in this application;

[0050] Figure 6 This is a schematic diagram of the microstructure provided in this application;

[0051] Figure 7 This is a top view of another acoustic wave device provided in this application;

[0052] Figure 8 This is an equivalent circuit diagram of another acoustic wave device provided in this application;

[0053] Figure 9 This is a top view of another acoustic wave device provided in this application;

[0054] Figure 10 This is an equivalent circuit diagram of another acoustic wave device provided in this application;

[0055] Figure 11 This is a top view of yet another acoustic wave device provided in this application;

[0056] Figure 12 This is an equivalent circuit diagram of another acoustic wave device provided in this application;

[0057] Figure 13 This is a cross-sectional schematic diagram of another acoustic wave device provided in this application;

[0058] Figure 14 This is a top view of another acoustic wave device provided in this application;

[0059] Figure 15This is an equivalent circuit diagram of another acoustic wave device provided in this application;

[0060] Figures 16A-16O This application provides Figure 3 The diagram shows the fabrication process of the acoustic device. Detailed Implementation

[0061] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the relevant invention and not intended to limit the invention. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0062] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0063] See Figures 1-2 , Figure 1 This is a schematic diagram of the cross-sectional structure of an acoustic wave device provided in this application. Figure 2 This is a top view of an acoustic wave device provided in this application. Figure 1 yes Figure 2 A schematic diagram of the cross-sectional structure of the medium acoustic wave device obtained by cutting along line AB-AB'.

[0064] The acoustic wave device includes at least two regions, namely a first region and a second region. The first region is fabricated as a first resonator PCM1, and the second region is fabricated as a second resonator PCM2. The first resonator PCM1 includes a first piezoelectric structure 11, and the second resonator PCM2 includes a reflective structure 12 and a second piezoelectric structure 13. Specifically, as shown... Figure 1 As shown, the reflective structure 12 is disposed between the first piezoelectric structure 11 and the second piezoelectric structure 13. The stacking direction of the first piezoelectric structure 11 is perpendicular to the substrate 10, and the stacking direction of the second piezoelectric structure 13 is parallel to the substrate 10, that is, the stacking direction of the first piezoelectric structure 11 is perpendicular to the stacking direction of the second piezoelectric structure 12. Further, the stacking direction of the first piezoelectric structure 11 is the direction in which the layers are stacked sequentially from bottom to top, and the stacking direction of the second piezoelectric structure 13 is the direction in which the layers are stacked sequentially from left to right.

[0065] In one embodiment, the first resonator PCM1 and the second resonator PCM2 may be thin-film bulk acoustic resonators. It is understood that in other embodiments, the first resonator PCM1 and the second resonator PCM2 may also be other types of resonators, and this embodiment does not limit this.

[0066] In one embodiment, the first resonator PCM1 can be an air-gap type thin-film bulk acoustic resonator, and the second resonator PCM2 can be a solidly mounted thin-film bulk acoustic resonator (SMR).

[0067] In another embodiment, such as Figure 1 As shown, the acoustic device may also include an electrode connection line 14, which may include two parts: an electrode connection line for an air gap type thin film bulk acoustic resonator (denoted as the first sub-connection line) and an electrode connection line for a solid-state assembled thin film bulk acoustic resonator (denoted as the second sub-connection line).

[0068] In one implementation, such as Figure 1 As shown, the reflective structure 12 includes at least two reflective layers. A second sub-connector is positioned above the reflective structure 12 and the second piezoelectric structure 13 of the solid-state assembled thin-film bulk acoustic resonator, with one end connected to the first sub-connector and the other end connected to the second top electrode 133; since the second top electrode 133 is shielded by the pad 15, therefore... Figure 1 The second top electrode 133 is not shown in the diagram. At this time, a notch is provided at the end of the second bottom electrode away from the substrate 10 (e.g., ...). Figure 1 As shown (not marked), the gap is filled with insulating material to prevent the second resonator PCM2 from being open-circuited. This insulating material can be filled with a low acoustic impedance material or a high acoustic impedance material.

[0069] Alternatively, the reflective structure 12 can be a through-hole. The second sub-connecting line and... Figure 1 The electrode connection lines of the solid-state assembled thin-film bulk acoustic resonator shown are the same. In this case, a notch is provided at the end of the second bottom electrode 131 away from the substrate 10. This notch can be connected to a through hole.

[0070] In another embodiment, the reflective structure 12 includes at least two reflective layers, or the reflective structure 12 is a through-hole. A second sub-connection line is disposed above the reflective structure 12 and the second piezoelectric structure 13, with one end connected to the first sub-connection line and the other end connected to the second bottom electrode 131. In this case, a notch is provided at the end of the second top electrode 133 furthest from the substrate 10, and this notch is filled with an insulating material to prevent the second resonator PCM2 from being disconnected. This insulating material can be a low acoustic impedance material or a high acoustic impedance material.

[0071] Alternatively, the second sub-connection line may not extend directly above the second top electrode 133 to avoid connection with the second top electrode 133. For example, the second sub-connection line may extend above the second bottom electrode 131 or the second piezoelectric layer 132.

[0072] In yet another embodiment, such as Figure 1As shown, the acoustic wave device may further include a pad 15 disposed above the substrate 10. The pad 15 is connected to the first resonator PCM1 or the second resonator PCM2, and is used to extract the electrical signal of the first resonator PCM1 or the second resonator PCM2. Specifically, the pad 15 is connected to the first bottom electrode 111, the first top electrode 113, the second bottom electrode 131, or the second top electrode 133.

[0073] The technical solution provided in this embodiment, by employing a thin-film bulk acoustic wave resonator (BAS) including a reflective structure and a piezoelectric structure, prevents lateral acoustic energy leakage between adjacent BAS resonators containing a reflective structure, effectively improving the quality factor of the acoustic wave device. Simultaneously, the stacking directions of the piezoelectric structures of adjacent BAS resonators are perpendicular to each other. Compared to existing technologies that use identical structures for adjacent BAS resonators, the technical solution provided in this application effectively reduces the horizontal size of the BAS resonator, significantly improving the utilization rate per unit area of ​​the wafer.

[0074] See Figures 3-8 , Figure 3 This is a schematic diagram of the cross-sectional structure of another acoustic wave device provided in this application. Figure 3 yes Figure 4 The diagram shows a cross-sectional structure of the acoustic device obtained by cutting along line AB-AB'. Figure 4 This is a top view of yet another acoustic wave device provided in this application. (Example) Figure 4 As shown, the acoustic device includes at least three regions, namely a first region, a second region, and a third region. The first region is adjacent to the second region, and the second region is adjacent to the third region.

[0075] like Figure 4 As shown, the first and third regions are fabricated as air-gap type thin-film bulk acoustic resonators (PCM1, PCM3), and the second region is fabricated as a solid-state assembled type thin-film bulk acoustic resonator PCM2. Figure 5 yes Figure 4 The equivalent circuit of the acoustic wave device is shown. For example... Figure 5 As shown, air-gap type thin-film bulk acoustic wave resonator PCM1 and air-gap type thin-film bulk acoustic wave resonator PCM3 are connected in series, and solid-state assembled type thin-film bulk acoustic wave resonator PCM2 is connected in parallel with air-gap type thin-film bulk acoustic wave resonator PCM1 and air-gap type thin-film bulk acoustic wave resonator PCM3.

[0076] In one embodiment, see further. Figure 3The air-gap type thin-film bulk acoustic resonator (PCM1 or PCM3) includes a first piezoelectric structure 11, and the solid-state assembled type thin-film bulk acoustic resonator PCM2 includes a reflective structure 12 and a second piezoelectric structure 13. The reflective structure 12 is located between the first piezoelectric structure 11 and the second piezoelectric structure 13, and the stacking direction of the first piezoelectric structure 11 is perpendicular to the stacking direction of the second piezoelectric structure 13.

[0077] like Figure 3 As shown, the acoustic wave device also includes multiple cavities (K1, K2, K3), which can be referred to as air gaps. These cavities are used to prevent acoustic waves from leaking to the underlying substrate.

[0078] The air-gap type thin-film bulk acoustic resonator (PCM1 or PCM3) includes a first piezoelectric structure 11, which can also be referred to as a sandwich structure. Specifically, the first piezoelectric structure 11 includes a first bottom electrode 111, a first piezoelectric layer 112 disposed on the upper surface of the first bottom electrode 111, and a first top electrode 113 disposed on the upper surface of the first piezoelectric layer 112.

[0079] In one embodiment, such as Figure 3 As shown, the solid-state assembled thin-film bulk acoustic resonator PCM2 may include two reflective structures 12, which are respectively disposed on both sides of the second piezoelectric structure 11; the orthographic projection of the reflective structure 12 can fall outside the region where the cavity K2 is located, and the orthographic projection of the second piezoelectric structure 13 falls within the region where the cavity K2 is located.

[0080] The reflective structure 12 includes at least two reflective layers, namely a first reflective layer 121 and a second reflective layer 122. The first reflective layer 121 may be a low acoustic impedance reflective layer with a thickness of one-quarter wavelength, and the second reflective layer 122 may be a high acoustic impedance material with a thickness of one-quarter wavelength. The first reflective layer 121 and the second reflective layer 122 are alternately constructed; or, the first reflective layer 121 may be made of a high acoustic impedance material, and the second reflective layer 122 may be made of a low acoustic impedance material. Specifically, the aforementioned low acoustic impedance material may be an insulating layer, and the aforementioned second reflective layer 122 may be a metal layer. The more layers of the first reflective layer 121 and the second reflective layer 122, the greater the reflection coefficient, and the higher the quality factor of the resulting acoustic device. The first reflective layer 121 and the second reflective layer 122 are alternately stacked along a direction parallel to the substrate 10, or the second reflective layer 122 and the first reflective layer 121 are alternately stacked along a direction parallel to the substrate 10.

[0081] The second piezoelectric structure 13 includes a second bottom electrode 131, a second piezoelectric layer 132, and a second top electrode 133. The second bottom electrode 131, the second piezoelectric layer 132, and the second top electrode 133 are stacked sequentially from left to right, and their stacking direction is perpendicular to the stacking direction of the first piezoelectric structure 11 from bottom to top.

[0082] In one embodiment, one of the two reflective structures 12 is a reflective structure 12 including at least two reflective layers, and the other is a through hole. Alternatively, both reflective structures 12 are through holes.

[0083] In another embodiment, such as Figure 6 As shown, Figure 6 This is a schematic diagram of the microstructure provided in this application. Figure 6 Is Figure 3 Based on the air-gap type thin-film bulk acoustic resonator PCM1 shown, a schematic diagram is provided on the air-gap type thin-film bulk acoustic resonator PCM1 with one or more microstructures. The microstructures can be cavities, protrusions, recesses, air bridges, or air wing structures, etc. Figure 6 The illustrations are for illustrative purposes only and should not be construed as limiting interpretations. Figure 6 The first piezoelectric structure shown includes a first bottom electrode 111, a first piezoelectric layer 112, and a first top electrode 113.

[0084] like Figure 6 As shown in (a), a first cavity 31 can be provided on the first piezoelectric layer 112, such that the end of the first bottom electrode 111 close to the first cavity 31 has an air wing structure, and a second cavity 32 is provided on the substrate 10 to the right of the cavity K1.

[0085] like Figure 6 As shown in (b), a first cavity 31 is provided in the first piezoelectric electrode 112, such that the first bottom electrode 111 has an air wing structure at the end close to the first cavity 31; at the same time, a second cavity 32 is provided between the substrate 10 and the first piezoelectric electrode 112.

[0086] like Figure 6 As shown in (c), one end of the first piezoelectric layer 121 is partially hollowed out, that is, a first cavity 31 and a second cavity 32 are provided on the first piezoelectric layer 121.

[0087] like Figure 6 As shown in (d), one end of the first piezoelectric layer 121 is completely hollowed out, that is, a third cavity 30 is set on the first piezoelectric layer 121.

[0088] The technical solution provided in this embodiment can improve the quality factor of acoustic wave devices by setting one or more microstructures.

[0089] In another embodiment, such as Figure 3 As shown, the acoustic wave device may also include an electrode connection line 14, which may include three parts: the electrode connection line of the air gap type thin film bulk acoustic wave resonator PCM1 (denoted as the first sub-connection line), the electrode connection line of the solid-state assembled thin film bulk acoustic wave resonator PCM2 (denoted as the second sub-connection line), and the electrode connection line of the air gap type thin film bulk acoustic wave resonator PCM3 (denoted as the third sub-connection line).

[0090] The second sub-connecting line is disposed above the reflective structure 12 and the second piezoelectric structure 13, with one end connected to the first sub-connecting line and the other end connected to the third sub-connecting line; moreover, a notch is provided at the end of the second top electrode 133 away from the substrate 10, or a notch is provided at the end of the first bottom electrode 131 away from the substrate 10, and the notch can be filled with the same material as the first reflective layer 121 or the second reflective layer 122.

[0091] Furthermore, such as Figure 3 As shown, the first sub-connection line is positioned above the first top electrode 113 of the air-gap type thin-film bulk acoustic wave resonator PCM1, and its position is adjacent to the reflection structure 12 of the solid-state assembled thin-film bulk acoustic wave resonator PCM2; the third sub-connection line is positioned above the first top electrode 113 of the air-gap type thin-film bulk acoustic wave resonator PCM3, and its position is adjacent to the reflection structure 12 of the solid-state assembled thin-film bulk acoustic wave resonator PCM2.

[0092] The orthographic projection of the second sub-electrode connection line on the substrate 10 is perpendicular to the orthographic projections of the first and third sub-electrode connection lines on the substrate 10, such as... Figure 4 As shown.

[0093] In another embodiment, such as Figure 3 As shown, the acoustic wave device also includes pads 15a-15c, which are disposed on the upper surface of the substrate 10. Pad 15a is connected to an air-gap type thin-film bulk acoustic wave resonator PCM1, and is used to extract the electrical signal of the air-gap type thin-film bulk acoustic wave resonator PCM1; pad 15b is connected to a solid-state assembled type thin-film bulk acoustic wave resonator PCM2, and is used to extract the electrical signal of the solid-state assembled type thin-film bulk acoustic wave resonator PCM2; pad 15c is connected to an air-gap type thin-film bulk acoustic wave resonator PCM3, and is used to extract the electrical signal of the air-gap type thin-film bulk acoustic wave resonator PCM3.

[0094] In other embodiments, see Figure 7 , Figure 7This is a top view of another acoustic device provided in this application, wherein the first and third regions are fabricated as solid-state assembled thin-film bulk acoustic resonators (PCM1, PCM3), and the second region is fabricated as an air-gap type thin-film bulk acoustic resonator PCM2.

[0095] Furthermore, such as Figure 8 As shown, Figure 8 yes Figure 7 The equivalent circuit of the acoustic wave device shown is as follows: solid-state assembled thin-film bulk acoustic resonator PCM1 and solid-state assembled thin-film bulk acoustic resonator PCM3 are connected in series, and air-gap type thin-film bulk acoustic resonator PCM2 is connected in parallel with solid-state assembled thin-film bulk acoustic resonator PCM1 and solid-state assembled thin-film bulk acoustic resonator PCM3.

[0096] In one embodiment, a solid-state assembled thin-film bulk acoustic wave resonator (PCM1 or PCM3) with a reflective structure is respectively disposed on both sides of the air-gap type thin-film bulk acoustic wave resonator PCM2. The reflective structure of the solid-state assembled thin-film bulk acoustic wave resonator PCM1 and the solid-state assembled thin-film bulk acoustic wave resonator PCM3 are both reflective structures including at least two reflective layers, or both are through holes, or one side is a through hole and the other side is a reflective structure including two reflective layers.

[0097] The technical solution provided in this application designs a thin-film bulk acoustic wave resonator (BAS) with a reflective structure, which prevents acoustic energy leakage in the lateral direction of adjacent BAS resonators, effectively improving the quality factor of the acoustic wave device. Simultaneously, the piezoelectric structures of adjacent BAS resonators are stacked perpendicularly to each other. Compared to existing technologies that use identical structures for adjacent BAS resonators, the technical solution provided in this application effectively reduces the horizontal size of the BAS resonator, significantly improving the utilization rate per unit area of ​​the wafer.

[0098] See Figure 9 , Figure 9 This is a top view of another acoustic wave device provided in this application. The acoustic wave device includes two air-gap type thin-film bulk acoustic wave resonators (PCM1, PCM4) and two solid-state assembled type thin-film bulk acoustic wave resonators (PCM2, PCM3), with the solid-state assembled type thin-film bulk acoustic wave resonators PCM2 and PCM3 disposed between the air-gap type thin-film bulk acoustic wave resonator PCM1 and the solid-state assembled resonator PCM4.

[0099] Furthermore, such as Figure 10 As shown, Figure 10 for Figure 9The equivalent circuit of the acoustic wave device is shown. Air-gap type thin-film bulk acoustic wave resonator PCM1 and air-gap type thin-film bulk acoustic wave resonator PCM4 are connected in series. Solid-state assembled type thin-film bulk acoustic wave resonator PCM2 is connected in parallel with air-gap type thin-film bulk acoustic wave resonator PCM1, solid-state assembled type thin-film bulk acoustic wave resonator PCM3 and air-gap type thin-film bulk acoustic wave resonator PCM4. Solid-state assembled type thin-film bulk acoustic wave resonator PCM3 is connected in parallel with solid-state assembled type thin-film bulk acoustic wave resonator PCM2, air-gap type thin-film bulk acoustic wave resonator PCM1 and air-gap type thin-film bulk acoustic wave resonator PCM4.

[0100] The technical solution provided in this application sets two solid-state assembled thin-film bulk acoustic wave resonators on one side of the air-gap type thin-film bulk acoustic wave resonator. This prevents the leakage of acoustic energy in the lateral direction of the air-gap type thin-film bulk acoustic wave resonator, effectively improving the quality factor of the acoustic wave device. Furthermore, since the stacking direction of the piezoelectric structure of the solid-state assembled thin-film bulk acoustic wave resonator is perpendicular to the stacking direction of the piezoelectric structure of the air-gap type thin-film bulk acoustic wave resonator, compared with the prior art in which multiple adjacent bulk acoustic wave resonators adopt the same structure, the technical solution provided in this application further saves the size of the acoustic wave device in the horizontal direction by continuously setting two or more solid-state assembled thin-film bulk acoustic wave resonators on one side of the air-gap type thin-film bulk acoustic wave resonator. This achieves the technical effect of placing more resonators on a limited area, that is, it can further improve the utilization rate of wafer unit area.

[0101] See Figure 11 , Figure 11 This is a top view of another acoustic device provided in this application. The acoustic device includes three air-gap type thin-film bulk acoustic resonators (PCM1, PCM3, PCM5) and two solid-state assembled type thin-film bulk acoustic resonators (PCM2, PCM4).

[0102] Solid-state assembled thin-film bulk acoustic resonator PCM2 is positioned between air-gap thin-film bulk acoustic resonator PCM1 and air-gap thin-film bulk acoustic resonator PCM3, and solid-state assembled thin-film bulk acoustic resonator PCM4 is positioned between air-gap thin-film bulk acoustic resonator PCM3 and air-gap thin-film bulk acoustic resonator PCM5.

[0103] Furthermore, such as Figure 12 As shown, Figure 12 for Figure 11The equivalent circuit of the acoustic wave device is shown. Air-gap type thin-film bulk acoustic wave resonators PCM1, PCM3, and PCM5 are connected in series; solid-state assembled thin-film bulk acoustic wave resonator PCM2 is connected in parallel with air-gap type thin-film bulk acoustic wave resonators PCM1 and PCM3; and solid-state assembled thin-film bulk acoustic wave resonator PCM4 is connected in parallel with air-gap type thin-film bulk acoustic wave resonators PCM3 and PCM5.

[0104] The technical solution provided in this application involves setting a solid-state assembled thin-film bulk acoustic wave resonator on each side of the air-gap type thin-film bulk acoustic wave resonator (PCM3). This simultaneously prevents lateral acoustic energy leakage between the two adjacent air-gap type PCM3 resonators, effectively improving the quality factor of the acoustic wave device. Furthermore, each solid-state assembled thin-film bulk acoustic wave resonator includes two reflective structures, and the piezoelectric structures of adjacent thin-film bulk acoustic wave resonators are stacked perpendicularly to each other. This further reduces the size of the thin-film bulk acoustic wave resonator in the lateral space, effectively improving the utilization rate per unit area of ​​the wafer.

[0105] See Figure 13 , Figure 13 This is a cross-sectional schematic diagram of another acoustic wave device provided in this application. The acoustic wave device includes six air-gap type thin-film bulk acoustic resonators (PCM1, PCM3, PCM4, PCM6, PCM7, PCM9) and three solid-state mounted type thin-film bulk acoustic resonators (PCM2, PCM5, PCM8). The structure of the air-gap type thin-film bulk acoustic resonators (PCM1, PCM3, PCM4, PCM6, PCM7, PCM9) is similar to... Figure 3 The air-gap type thin-film bulk acoustic wave resonator PCM1 shown has the same structure, and the solid-state assembled type thin-film bulk acoustic wave resonators (PCM2, PCM5, PCM8) have the same structure. Figure 3 The solid-state assembled thin-film bulk acoustic wave resonator PCM2 shown has the same structure, so it will not be described again here. The solid-state assembled thin-film bulk acoustic wave resonator can be placed between two adjacent air-gap thin-film bulk acoustic wave resonators.

[0106] Furthermore, such as Figure 14 and Figure 15 As shown, Figure 14 for Figure 13 The top view of the acoustic device shown. Figure 15 for Figure 13The equivalent circuit of the acoustic wave device is shown. Air-gap type thin-film bulk acoustic resonators PCM1, PCM3, PCM4, PCM6, PCM7, and PCM9 are connected in series. Solid-state assembled thin-film bulk acoustic resonator PCM2 is connected in parallel with air-gap type thin-film bulk acoustic resonators PCM1 and PCM3. Solid-state assembled thin-film bulk acoustic resonator PCM5 is connected in parallel with air-gap type thin-film bulk acoustic resonators PCM4 and PCM6. Solid-state assembled thin-film bulk acoustic resonator PCM8 is connected in parallel with air-gap type thin-film bulk acoustic resonators PCM7 and PCM9.

[0107] The technical solution provided in this application sets a solid-state assembled thin-film bulk acoustic wave resonator between two adjacent air-gap type thin-film bulk acoustic wave resonators. This prevents the air-gap type thin-film bulk acoustic wave resonators from having lateral acoustic energy leakage, thereby improving the quality factor of the acoustic wave device. At the same time, the structure of the solid-state assembled thin-film bulk acoustic wave resonator can save the size of the thin-film bulk acoustic wave resonator occupying lateral space. This kind of acoustic wave device can effectively improve the utilization rate of wafer unit area.

[0108] In addition to the structure of the acoustic wave device in the above embodiments, this application also provides the fabrication process of the acoustic wave device, which is described below. Figure 3 The fabrication process of an acoustic wave device is illustrated using the shown acoustic wave device as an example. This process includes: providing a substrate 10 in advance; then, forming a first piezoelectric structure on the substrate 10 to fabricate a first resonator; and then forming a reflective structure and a second piezoelectric structure on the substrate 10 to fabricate a second resonator; wherein the reflective structure is located between the first and second piezoelectric structures, and the stacking direction of the first piezoelectric structure is perpendicular to the stacking direction of the second piezoelectric structure. For example, three regions are defined on the substrate 10: the first region is fabricated as an air-gap type thin-film bulk acoustic wave resonator, the second region is fabricated as a solid-state assembled type thin-film bulk acoustic wave resonator, and the third region is fabricated as an air-gap type thin-film bulk acoustic wave resonator.

[0109] In one embodiment, reference is made to Figures 16A-16O A detailed explanation of the above production process may include:

[0110] First step, such as Figure 16AAs shown, multiple grooves (M1, M2, M3) are formed on the upper surface of the substrate 10; then, a sacrificial material is deposited on the upper surface of the substrate 10 to fill the grooves (M1, M2, M3). The sacrificial material can be phosphosilicate glass (PSG); then, the sacrificial material on the upper surface of the substrate 10 is removed by a chemical mechanical polishing (CMP) process, so that the upper surface of the sacrificial material in the grooves (M1, M2, M3) is parallel to the upper surface of the substrate 10, thereby forming a sacrificial layer 114.

[0111] Furthermore, the multiple grooves include two types of grooves. The first type of groove can be referred to as the first groove (M1, M3), and the second type of groove can be referred to as the second groove M2. The area occupied by the first groove M1 and the first groove M3 on the substrate 10 is larger than the area occupied by the second groove M2 on the substrate 10. During the process, different groove widths can be pre-set to meet the design requirements of different thin-film bulk acoustic resonators. This step is not mandatory, and the grooves can be omitted.

[0112] The second step, as Figure 16B As shown, a first bottom electrode 111 is formed above the first groove (including M1 and M3) or directly on the substrate 10.

[0113] Physical vapor deposition (PVD) process was used in Figure 16A An electrode material layer is formed on the structure shown, and the electrode material layer is imaged to form a first bottom electrode 111; the material of the electrode material layer can be a metal such as molybdenum, gold or aluminum.

[0114] The third step, as Figure 16C As shown, in Figure 16B A first piezoelectric layer 112 is formed on the structure shown. The material of the first piezoelectric layer 112 can be aluminum nitride or zinc oxide, etc.

[0115] Step four, as Figure 16D As shown, PVD process is used in Figure 16C The first top electrode 113 is formed on the structure shown.

[0116] The material of the first top electrode 113 can be a metal such as molybdenum, gold, or aluminum. The material of the first top electrode 113 can be the same as or different from the material of the first bottom electrode 111. Thus, a first piezoelectric structure is formed above the first groove M1, and simultaneously, a first piezoelectric structure is also formed above the first groove M3.

[0117] The first resonator is fabricated above the first groove M1 and the first groove M3 through the above steps. Then, a reflective structure and a second piezoelectric structure are formed above the substrate 10 to fabricate the second resonator. The fabrication of the second resonator may include the steps of fabricating the reflective structure and fabricating the second piezoelectric structure. Fabricating the reflective structure may include steps five and six, and fabricating the second piezoelectric structure may include step seven.

[0118] Step 5, as Figure 16E As shown, a first acoustic impedance material is filled on top of the substrate 10 to form a first material layer 12'.

[0119] exist Figure 16D In the structure shown, a first acoustic impedance material is deposited between two adjacent first piezoelectric structures to form a first material layer 12'. Specifically, the first acoustic impedance material can be a low acoustic impedance material, such as silicon dioxide, i.e., silicon dioxide is filled on the substrate 10 to form the first material layer 12'.

[0120] The sixth step is to process the first material layer 12' to form a reflective structure.

[0121] Specifically, the following production process may be included:

[0122] A1) As Figure 16F As shown, for Figure 16E The first patterned area of ​​the first material layer 12' formed in the substrate is patterned to form a plurality of first vias W1. The lower surface of each first via W1 is in contact with the substrate 10. The first patterned area refers to the area in the first material layer 12' used to form a reflective structure, such as... Figure 16F As shown, the area indicated by the dashed box in the first material layer 12'. The number of first through-holes can be adjusted according to actual design needs. For example, two first through-holes W1 can be formed. One first through-hole W1 is formed on the substrate 10 between the first groove M1 and the second groove M2, and the area of ​​the orthographic projection of this first through-hole W1 on the substrate 10 can be smaller than the area of ​​the substrate 10 between the first groove M1 and the second groove M2; while the other first through-hole W1 is formed on the substrate 10 between the second groove M2 and the first groove M3, and the area of ​​the orthographic projection of this first through-hole W1 on the substrate can be smaller than the area of ​​the substrate 10 between the second groove M2 and the third groove M3. In this case, these two first through-holes W1 serve as a reflective structure to prevent the leakage of acoustic energy from the first resonator in the lateral direction.

[0123] For example, such as Figure 16FAs shown, multiple first through-holes W1 are formed on the substrates 10 on both sides of the second groove M2. The number of these first through-holes W1 on both sides of the second groove M2 can be the same or different. For example, at least one first through-hole W1 is formed on the substrate 10 on the left side of the second groove M2. The first material layer adjacent to the first through-hole W1 is used to form a first reflective layer 121. These first through-holes W1 await subsequent filling with a second acoustic impedance material to form a second reflective layer 122 alternating with the first reflective layer 121. At the same time, at least one first through-hole W1 is formed on the substrate 10 on the right side of the second groove M2. These first through-holes W1 await filling with a second acoustic impedance material to form a second reflective layer 122 alternating with the first reflective layer 121. The alternating first reflective layer 121 and second reflective layer 122 form a reflective structure (e.g., Figure 16G (As shown).

[0124] For example, a first through-hole W1 is formed on the substrate 10 to the left of the second groove M2. The area of ​​the orthographic projection of the first through-hole W1 onto the substrate 10 can be smaller than the area of ​​the substrate 10 between the first groove M1 and the second groove M2. This first through-hole W1 serves as a reflective structure to prevent the leakage of acoustic energy from the first resonator on the left side of the second groove M2 in a laterally existing manner. Simultaneously, at least one first through-hole W1 is formed on the substrate 10 to the right of the second groove M2. These first through-holes W1 await subsequent filling with a second acoustic impedance material to form a second reflective layer 122 alternating with the first reflective layer 121. That is, the formation of the first through-hole W1 on the left side of the second groove M2 serves as a reflective structure, while the formation on the right side of the second groove M2 constitutes a reflective structure including at least two reflective layers. Alternatively, the formation of the first through-hole W1 on the right side of the second groove M2 serves as a reflective structure, while the formation on the left side of the second groove M2 constitutes a reflective structure including at least two reflective layers.

[0125] A2) such as Figure 16G As shown, in Figure 16F In the structure shown, a second acoustic impedance material is deposited in each first through-hole W1 using a PVD process to form a second reflective layer 122.

[0126] By patterning the first patterned region of the first material layer 12', at least one first through-hole W1 is obtained, which is used as a reflective structure. Alternatively, the first patterned region of the first material layer 12' is first patterned to obtain at least one first through-hole W1; then the first material layer 12' adjacent to the first through-hole W1 within the first patterned region is used as a first reflective layer 121, and a second acoustic impedance material is deposited in the first through-hole W1 to form a second reflective layer 122. The first reflective layer 121 and the second reflective layer 122 are alternately arranged to form a reflective structure 12. The second acoustic impedance material can be a high acoustic impedance material such as molybdenum, tungsten, or tungsten.

[0127] The thin-film bulk acoustic resonator with a reflective structure proposed in this application can prevent acoustic energy leakage in the transverse direction of the thin-film bulk acoustic resonator adjacent to the reflective structure, effectively improving the quality factor of the thin-film bulk acoustic resonator.

[0128] The seventh step is to process the remaining first material layer 12' after forming the reflective structure 12 to form the second piezoelectric structure.

[0129] The following production steps may be included:

[0130] B1) such as Figure 16H As shown, in Figure 16G Based on the structure shown, the first material layer 12' located in the middle region (i.e., the second patterned region of the first material layer 12') undergoes a second patterning process to form the second through-hole W2 and the third through-hole W3. This second patterned region refers to the area in the first material layer used to form the second piezoelectric structure, such as... Figure 16H As shown, the second material layer between the two reflective structures 12 is the second patterned region.

[0131] The second through-hole W2 and the third through-hole W3 await subsequent filling with different metal materials to form different electrodes. The patterning process can be achieved using dry etching and wet etching processes. That is, the second patterned area of ​​the first material layer 12' is patterned to obtain the second through-hole W2 and the third through-hole W3, with the second through-hole W2 close to the reflective structure 12 and the third through-hole W3 far away from the reflective structure 12.

[0132] B2) such as Figure 16I As shown, in Figure 16H Based on the structure shown, a metal material is filled into the second through hole W2 to form the second bottom electrode 131. A metal material is filled into the third through hole W3 to form the second top electrode 133.

[0133] The second bottom electrode 131 and the second top electrode 133 were formed by depositing metal materials in the second through hole W2 and the third through hole W3, respectively.

[0134] B3) such as Figure 16J As shown, in Figure 16I Based on the structure shown, the first material layer 12' located in the middle region is patterned a third time to form the fourth through hole W4. The first material layer 12' located in the middle region refers to the portion of the first material layer 12' within the second patterned region, excluding the portion occupied by the second bottom electrode 131 and the second top electrode 133.

[0135] After forming the second bottom electrode 131 and the second top electrode 133, the first material layer 12' between the second bottom electrode 131 and the second top electrode 133 is patterned to obtain the fourth through hole W4, which is used to wait for subsequent filling of piezoelectric material.

[0136] B4) such as Figure 16K As shown, in Figure 16J Based on the structure shown, the fourth through hole W4 is filled with piezoelectric material to form a second piezoelectric layer 132. Thus, the second piezoelectric structure 13 is formed through steps B1-B4. The second piezoelectric structure 13 includes a second bottom electrode 131, a second piezoelectric layer 132, and a second top electrode 133.

[0137] B5) such as Figure 16L As shown, in Figure 16K Based on the structure shown, Figure 16K The second top electrode 133 shown is etched in a portion of S. Alternatively, a portion of the second bottom electrode 131 is etched at the end away from the substrate 10.

[0138] B6) such as Figure 16M As shown, in Figure 16L Based on the structure shown, an insulating material is deposited on the etched portion S. This insulating material can be the same first acoustic impedance material used in the first material layer 12'. Alternatively, an insulating material can be deposited on a portion of the second bottom electrode 131 etched away from the substrate 10; this insulating material can be either the first or second acoustic impedance material. That is, the end of the second bottom electrode 131 or the second top electrode 133 away from the substrate 10 is etched, and then an insulating material is deposited on the etched area to prevent short circuits in the second resonator.

[0139] Step 8, as Figure 16N As shown, in Figure 16M Based on the structure shown, an electrode connection line 14 is formed. Specifically, a metallic material is deposited at a predetermined position above the first top electrode 113 of the first piezoelectric structure 11 and above the reflective structure 12 and the second piezoelectric structure 13 to form the electrode connection line 14. The electrode connection line 14 is used to connect the first top electrode 113 and the second top electrode 133, or to connect the first top electrode 113 and the second bottom electrode 131.

[0140] Step 9, as Figure 16O As shown, in Figure 16NBased on the structure shown, pads 15 are formed at predetermined positions above the substrate 10 using a lift process. Pads 15 are connected to the first resonator or the second resonator to extract the electrical signals of the first resonator or the second resonator. After forming pads 15, the sacrificial layer 114 is released to form cavities (K1, K2, K3); pads 15 are made of a conductive material (e.g., Au).

[0141] By adopting the technical solution provided in this application, the acoustic energy leakage in the lateral direction of the thin-film bulk acoustic resonator adjacent to the thin-film bulk acoustic resonator containing the reflective structure can be prevented, which significantly improves the quality factor of the acoustic device. At the same time, the thin-film bulk acoustic resonator containing the reflective structure, because the stacking direction of its piezoelectric structure is designed to be the same as the horizontal direction of the substrate, can effectively reduce the size of the thin-film bulk acoustic resonator in the horizontal direction and significantly improve the wafer unit area utilization.

[0142] This application proposes that the aforementioned acoustic wave device can be used, in whole or in part, as a filter or a duplexer.

[0143] The above description is merely a preferred embodiment of the present invention and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention is not limited to the specific combination of the above-described technical features, but also includes other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above-described features with (but not limited to) technical features with similar functions disclosed in this invention.

Claims

1. An acoustic wave device, characterized in that, The acoustic wave device includes at least two regions, at least one of which is provided with a first resonator, and at least one region adjacent to the region where the first resonator is located is provided with a second resonator. The first resonator is an air-gap type thin-film bulk acoustic wave resonator and includes a first piezoelectric structure. The second resonator is a solid-state assembled type thin-film bulk acoustic wave resonator and includes a reflection structure and a second piezoelectric structure. The reflection structure is located between the first piezoelectric structure and the second piezoelectric structure, and the stacking direction of the first piezoelectric structure is perpendicular to the stacking direction of the second piezoelectric structure.

2. The acoustic device according to claim 1, characterized in that, The at least two regions include a first region, a second region, and a third region, wherein the first region is adjacent to the second region, and the second region is adjacent to the third region; Both the first and third regions are equipped with air-gap type thin-film bulk acoustic resonators, and the second region is equipped with a solid-state assembled type thin-film bulk acoustic resonator; or, Both the first region and the third region are provided with solid-state assembled thin-film bulk acoustic resonators, and the second region is provided with an air-gap type thin-film bulk acoustic resonator.

3. The acoustic device according to claim 1, characterized in that, The at least two regions include at least four regions, which are sequentially adjacent to each other. The first and last regions are provided with the air gap type thin film bulk acoustic resonator, and the other regions, except for the first and last regions, are provided with solid-state assembled type thin film bulk acoustic resonator.

4. The acoustic device according to claim 2 or 3, characterized in that, The reflective structure is provided on both sides of the second piezoelectric structure.

5. The acoustic device according to any one of claims 1-3, characterized in that, The reflective structure includes at least two reflective layers, and the stacking direction of the at least two reflective layers is the same as the stacking direction of the second piezoelectric structure.

6. The acoustic device according to any one of claims 1-3, characterized in that, The reflective structure is a through hole, and the opening direction of the through hole is the same as the stacking direction of the first piezoelectric structure.

7. The acoustic device according to any one of claims 1-3, characterized in that, The acoustic device includes a substrate and at least two cavities formed on the substrate, each cavity corresponding to one of the regions; The first piezoelectric structure is disposed above at least one of the at least two cavities, the second piezoelectric structure is disposed above the cavity adjacent to the cavity where the first piezoelectric structure is disposed, and the orthographic projection of the second piezoelectric structure on the substrate falls within the cavity adjacent to the cavity where the first piezoelectric structure is disposed.

8. The acoustic device according to claim 7, characterized in that, The first piezoelectric structure includes a first bottom electrode, a first piezoelectric layer, and a first top electrode stacked sequentially from the substrate side; The reflective structure includes a first reflective layer and a second reflective layer alternately stacked along a direction perpendicular to the stacking direction of the first piezoelectric structure; or, the reflective structure includes a through-hole extending along a direction perpendicular to the stacking direction of the first piezoelectric structure, with the substrate located below the through-hole. The second piezoelectric structure includes a second bottom electrode, a second piezoelectric layer, and a second top electrode, which are sequentially stacked along a direction perpendicular to the stacking direction of the first piezoelectric structure.

9. The acoustic device according to claim 8, characterized in that, The acoustic device further includes an electrode connection line disposed above the reflective structure and the second piezoelectric structure, the electrode connection line being connected to the first top electrode and the second bottom electrode.

10. The acoustic device according to claim 9, characterized in that, The acoustic wave device also includes a pad, which is disposed above the substrate and is connected to the first resonator or the second resonator for leading out the electrical signal of the first resonator or the second resonator.

11. A method for manufacturing an acoustic wave device, characterized in that, The manufacturing method includes: Provide a substrate; A first piezoelectric structure is formed above the substrate to fabricate an air-gap type thin-film bulk acoustic resonator as the first resonator; A reflective structure and a second piezoelectric structure are formed above the substrate to fabricate a solid-state assembled thin-film bulk acoustic resonator as the second resonator. The reflective structure is located between the first piezoelectric structure and the second piezoelectric structure, and the stacking direction of the first piezoelectric structure is perpendicular to the stacking direction of the second piezoelectric structure.

12. The manufacturing method according to claim 11, characterized in that, The process of forming a reflective structure and a second piezoelectric structure above the substrate to fabricate a second resonator includes: A first acoustic impedance material is filled on top of the substrate to form a first material layer; The first material layer is processed to form the reflective structure; After the reflective structure is formed, the remaining first material layer is processed to form the second piezoelectric structure.

13. The manufacturing method according to claim 12, characterized in that, The process of processing the first material layer to form the reflective structure includes: The first patterned region of the first material layer is patterned to obtain at least one first through-hole, which is used as the reflective structure; or... The first patterned region of the first material layer is patterned to obtain at least one first through hole; the first material layer adjacent to the first through hole in the first patterned region is used as a first reflective layer, and a second acoustic impedance material is deposited in the first through hole to form a second reflective layer that is alternately arranged with the first reflective layer. The first reflective layer and the second reflective layer are alternately arranged to form the reflective structure. The first patterned region refers to the region in the first material layer used to form the reflective structure.

14. The manufacturing method according to claim 12 or 13, characterized in that, After forming the reflective structure, the remaining first material layer is processed to form the second piezoelectric structure, which includes a second bottom electrode, a second piezoelectric layer, and a second top electrode. The second patterned region of the first material layer is patterned to obtain a second through hole and a third through hole. The second patterned region refers to the region in the first material layer used to form the second piezoelectric structure. Metallic material is deposited in the second and third through holes to form the second bottom electrode and the second top electrode; After forming the second bottom electrode and the second top electrode, the first material layer between the second bottom electrode and the second top electrode is patterned to obtain the fourth through hole; A piezoelectric material is deposited within the fourth through-hole to form the second piezoelectric layer.

15. The manufacturing method according to claim 14, characterized in that, After forming the second piezoelectric structure, the fabrication method further includes: The end of the second bottom electrode or the second top electrode away from the substrate is etched to form a notch, and an insulating material is deposited in the notch; Metallic material is deposited above the first piezoelectric structure, the reflective structure, and the second piezoelectric structure to form electrode connection lines. The first piezoelectric structure includes a first bottom electrode, a first piezoelectric layer, and a first top electrode. The electrode connection lines are used to connect the first top electrode to the second top electrode or the second bottom electrode. A pad is formed on the substrate, and the pad is connected to the first resonator or the second resonator.

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