Bulk acoustic wave resonators, methods of formation, and related devices

Abstract

Embodiments of the present application provide a bulk acoustic wave resonator, a forming method and related equipment, the bulk acoustic wave resonator comprises a first substrate, a device main structure and a first support structure, the device main structure at least comprises a first electrode structure, a piezoelectric layer and a second electrode structure which are stacked in sequence, and the first substrate has a first cavity with the device main structure; a second substrate is bonded to the first substrate and covers the device main structure, and a second support structure is arranged on the second substrate and faces the device main structure; the device main structure has a second cavity with the second substrate, and the second support structure is bonded to the first support structure; a bonding auxiliary structure is located between the first support structure and the second support structure, and the bonding auxiliary structure is inserted into the first support structure and / or the second support structure. Embodiments of the present application improve the performance of the bulk acoustic wave filter.

Description

Technical Field

[0001] This application relates to the field of filter technology, specifically to a bulk acoustic resonator, its formation method, and related equipment. Background Technology

[0002] Film bulk acoustic resonators (FBARs), as one of the core components of RF (Radio Frequency) front-ends, are receiving increasing attention, primarily due to their high power, high bandwidth, and excellent roll-off performance, which effectively meet current RF performance requirements. In particular, compared to SAW (Surface Acoustic Wave) devices, FBARs offer significant advantages in high power because they utilize the longitudinal wave propagation mode of bulk sound waves, leveraging the excellent piezoelectric properties of AlN material for better energy conversion.

[0003] However, there is still a need to further improve the performance of existing bulk acoustic resonators. Summary of the Invention

[0004] In view of this, embodiments of this application provide a bulk acoustic resonator, a method for forming it, and related equipment to improve the performance of a bulk acoustic filter.

[0005] To address the aforementioned problems, the embodiments of this application provide the following technical solutions.

[0006] In a first aspect, embodiments of this application provide a bulk acoustic resonator, comprising: A first substrate, and a device main structure located on the first substrate and a first support structure surrounding the device main structure, wherein the device main structure includes at least a first electrode structure, a piezoelectric layer and a second electrode structure stacked in sequence, and a first cavity is provided between the first substrate and the device main structure. A second substrate covering the main structure of the device, and a second support structure disposed on the second substrate facing the main structure of the device; a second cavity is provided between the main structure of the device and the second substrate, and the second support structure is bonded to the first support structure; A bonding auxiliary structure is located between the first support structure and the second support structure, the bonding auxiliary structure being inserted into the first support structure and / or the second support structure.

[0007] Optionally, the bonding auxiliary structure is made of a metallic material or an insulating material, wherein the bonding auxiliary structure surrounds the main structure of the device; when the bonding auxiliary structure is made of a metallic material, the bonding auxiliary structure is disconnected from the main structure of the device or electrically connected to the main structure of the device. From the top view of the bulk acoustic resonator, the bonding auxiliary structure either surrounds the main structure of the device in a closed manner, or the bonding auxiliary structure does not surround the main structure of the device in a closed manner.

[0008] Optionally, the first support structure is connected to the second support structure, the bonding auxiliary structure is located on the first support structure and inserted into the second support structure; or, the bonding auxiliary structure is located on the second support structure and inserted into the first support structure; or, the bonding auxiliary structure is inserted into both the first support structure and the second support structure. Alternatively, a first dielectric adhesion layer, a bonding layer, and a second dielectric adhesion layer may be sequentially disposed between the first support structure and the second support structure, with the bonding auxiliary structure penetrating through the first dielectric adhesion layer and inserted into the bonding layer; or, the bonding auxiliary structure may penetrate through the second dielectric adhesion layer and be inserted into the bonding layer.

[0009] Optionally, the bonding aid structure includes multiple parallel auxiliary sub-protrusion rings, with an auxiliary interval between adjacent auxiliary sub-protrusion rings. The width of the auxiliary interval is a preset interval distance, which is 0.1-10 times the width of the auxiliary sub-protrusion ring.

[0010] Optionally, the bonding auxiliary structure further includes a protrusion ring connecting portion, which is located between the auxiliary sub-protrusion rings and connected to adjacent auxiliary sub-protrusion rings.

[0011] Optionally, the raised ring connecting portion is disposed in the corner area of ​​the bonding auxiliary structure.

[0012] Optionally, the main structure of the device further includes a first rewiring layer, and the bonding auxiliary structure is connected to the first rewiring layer.

[0013] Optionally, it also includes: a second wiring layer located on the side of the first substrate opposite to the main structure of the device, and a via connection portion penetrating the first substrate; The via connection portion electrically connects the first wiring layer and / or the bonding auxiliary structure to the second wiring layer.

[0014] Optionally, it also includes: a metal bump structure located on the side of the second redistribution layer opposite to the main structure of the device; The bonding aid structure is electrically connected to the metal bump structure based on the second rewiring layer; In the bonding auxiliary structure, the portion used to connect to the metal bump structure is provided with a raised ring connecting part.

[0015] Optionally, between the first support structure and the second support structure, the second support structure is connected to the first electrode structure, connected to the piezoelectric layer, or connected to the second electrode structure. The bonding auxiliary structure is located on the first electrode structure, the piezoelectric layer, or the second electrode structure that is connected to the second support structure; Wherein, the bottom area of ​​the bonding auxiliary structure is smaller than the projected area of ​​the first support structure or the second support structure on the first substrate.

[0016] Optionally, when the auxiliary protrusion ring is made of a metallic material, the auxiliary protrusion ring is fabricated in the same layer as the metallic structure in the first electrode structure or the second electrode structure.

[0017] Optionally, the bonding auxiliary structure is made of the same material as the first support structure, and the bonding auxiliary structure and the first support structure are an integral structure.

[0018] Secondly, embodiments of this application also provide a method for forming a bulk acoustic resonator, used to form a bulk acoustic resonator as described in the first aspect above, comprising: A device base structure is formed, the device base structure including a first substrate, a main device structure located on the first substrate and a first support structure surrounding the main device structure, the main device structure including at least a first electrode structure, a piezoelectric layer and a second electrode structure stacked in sequence, and a first cavity between the first substrate and the main device structure; A substrate prebonding structure is formed, the substrate prebonding structure including a second substrate and a second support structure located on the second substrate; A bonding auxiliary structure is formed on the side of the first support structure opposite to the first substrate or on the side of the second support structure opposite to the second substrate; The substrate pre-bonding structure is bonded to the device base structure, wherein the bonding auxiliary structure is inserted into the second support structure and / or the first support structure.

[0019] Thirdly, embodiments of this application also provide a filter, including: a bulk acoustic resonator as described above.

[0020] Fourthly, embodiments of this application also provide a communication device, including: a filter as described above.

[0021] Fifthly, embodiments of this application also provide a terminal, including: the filter as described above.

[0022] Compared with the prior art, the technical solution of this application has the following advantages: This application provides a bulk acoustic wave resonator, a method for forming it, and related equipment. The bulk acoustic wave resonator includes: a first substrate, a main device structure located on the first substrate, and a first support structure surrounding the main device structure. The main device structure includes at least a first electrode structure, a piezoelectric layer, and a second electrode structure stacked sequentially. A first cavity is formed between the first substrate and the main device structure. A second substrate covers the main device structure, and a second support structure is disposed on the second substrate facing the main device structure. A second cavity is formed between the main device structure and the second substrate. The second support structure is bonded to the first support structure. A bonding auxiliary structure is located between the first support structure and the second support structure, and the bonding auxiliary structure is inserted into the first support structure and / or the second support structure.

[0023] As can be seen, the bulk acoustic wave resonator provided in this application embodiment, through the bonding auxiliary structure located between the first support structure and the second support structure, inserts the bonding auxiliary structure into the first support structure or the second support structure during the bonding process, thereby increasing the bonding contact area at the bonding point, thereby increasing the bonding force and improving the sealing of the bonding, thus avoiding the infiltration of water vapor into the device and improving the performance of the device.

[0024] Furthermore, in an optional implementation, since the bonding assist protrusion ring surrounds the periphery of the main structure of the device, thereby improving the signal shielding performance, enhancing the purity of the signal during filter operation, and further improving the performance of the device. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of an optional bulk acoustic resonator. Figure 2 A perspective view of the integrated acoustic filter provided in an embodiment of the present invention from a top-down perspective; Figure 3 A schematic diagram of the integrated acoustic resonator provided in an embodiment of the present invention, viewed from a cross-sectional perspective. Figure 4Another structural example of the integrated acoustic resonator provided in an embodiment of the present invention is shown in a cross-sectional view. Figure 5 Another structural example of the integrated acoustic resonator provided in the embodiment of the present invention is shown in a cross-sectional view. Figure 6 Another structural example of the integrated acoustic resonator provided in the embodiment of the present invention is shown in a cross-sectional view. Figure 7 A perspective view of another bulk acoustic filter provided in an embodiment of the present invention from a top-down perspective; Figure 8 This is a structural example diagram of another bulk acoustic resonator provided in an embodiment of the present invention, viewed from a cross-sectional perspective. Figure 9 A cross-sectional view of another integrated acoustic resonator provided in an embodiment of the present invention. Figures 10 to 18 This is a schematic diagram of the structure corresponding to each step in one embodiment of the method for forming a bulk acoustic resonator provided in this application. Detailed Implementation

[0027] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application. In the various drawings, the same elements are represented by similar reference numerals. For clarity, the various parts in the drawings are not drawn to scale. In addition, some well-known parts may not be shown. For the sake of simplicity, the intermediate structure of the half-filter obtained after several steps can be described in one figure.

[0028] It should be understood that when describing the structure of a device, when referring to a layer or region as being "above" or "on top of" another layer or region, it can mean that it is directly above another layer or region, or that there are other layers or regions between it and another layer or region. Furthermore, if the device is flipped, that layer or region will be located "below" or "under" another layer or region.

[0029] In this application, the term "device structure" refers to the collective term for the entire semiconductor structure formed in the various steps of manufacturing the filter, including all layers or regions that have been formed. Many specific details of the invention, such as the structure, materials, dimensions, processing techniques, and methods of the device, are described below to provide a clearer understanding of the invention. However, as those skilled in the art will understand, the invention may be implemented without adhering to these specific details. In the embodiments of this application, "connection" refers to various connection methods, such as direct connection or indirect connection.

[0030] With the continuous evolution of radio frequency (RF) front-end technology, integration and miniaturization have become clear development trends. Filters, as key components for frequency control in the RF front-end, play an indispensable role in both signal transmission and reception, and are a major component of RF front-end systems. Therefore, promoting the miniaturization and integration of filters is particularly crucial.

[0031] Among them, the film bulk acoustic resonator (FBAR), as one of the core devices of RF (Radio Frequency) front-end, has the characteristics of high power, high bandwidth and excellent roll-off, which can better meet the current demand for RF performance and has become a research hotspot at present.

[0032] A bulk acoustic resonator is a device that supports the propagation of sound waves (i.e., elastic waves) within a solid material. (Reference) Figure 1 The diagram shows an optional bulk acoustic wave resonator, which includes a first substrate 1, a second substrate 2, and a first electrode structure (also called a bottom electrode) 3, a piezoelectric layer 4, and a second electrode structure (also called a top electrode) 5 located between the first substrate 1 and the second substrate 2. A first cavity is formed between the first substrate 1 and the first electrode structure 3, and a second cavity is formed between the second substrate 2 and the second electrode structure 5. In this example structure, the first electrode structure 3, the piezoelectric layer 4, and the second electrode structure 5 are the main structures of the device.

[0033] However, the performance of devices with existing device structures needs to be improved.

[0034] In view of this, embodiments of this application provide a bulk acoustic wave resonator, a method for forming it, and related equipment. The bulk acoustic wave resonator includes: a first substrate, a main device structure located on the first substrate, and a first support structure surrounding the main device structure. The main device structure includes at least a first electrode structure, a piezoelectric layer, and a second electrode structure stacked sequentially. A first cavity exists between the first substrate and the main device structure. A second substrate covers the main device structure, and a second support structure disposed on the second substrate facing the main device structure. A second cavity exists between the main device structure and the second substrate. The second support structure is bonded to the first support structure. A bonding auxiliary structure is located between the first support structure and the second support structure, and the bonding auxiliary structure is inserted into the first support structure and / or the second support structure.

[0035] As can be seen, the bulk acoustic wave resonator provided in this application embodiment, through the bonding auxiliary structure located between the first support structure and the second support structure, inserts the bonding auxiliary structure into the first support structure and / or the second support structure during the bonding process, thereby increasing the bonding contact area at the bonding point, thereby increasing the bonding force and improving the sealing of the bonding, thus avoiding the infiltration of water vapor into the device and improving the performance of the device.

[0036] The bonding auxiliary structure further surrounds the main structure of the device, thereby improving the signal shielding performance, enhancing the purity of the signal during filter operation, and further improving the performance of the device.

[0037] Furthermore, when the bonding auxiliary structure is made of a metallic material, it can serve as a heat dissipation structure to improve the power performance of the filter. In addition, the layer containing the bonding auxiliary structure can also be used to fabricate capacitors or inductors, further improving filter performance and reducing the fabrication of capacitors and inductors within the filter substrate, thereby reducing costs.

[0038] The following will provide a detailed description of the bulk acoustic resonator, its formation method, and related equipment provided in the embodiments of the present invention.

[0039] refer to Figures 2 to 4 ,in, Figure 2 This is a perspective view of the integrated acoustic filter provided in an embodiment of the present invention from a top-down perspective. Figure 3 and Figure 4 This is a structural example diagram of an integrated acoustic resonator provided in an embodiment of the present invention, viewed from a cross-sectional perspective. Figure 3 A schematic diagram of the integrated acoustic resonator provided in an embodiment of the present invention, viewed from a cross-sectional perspective. Figure 4 Another structural example of the integrated acoustic resonator provided in the embodiment of the present invention is shown in cross-sectional view.

[0040] refer to Figures 2 to 4 The bulk acoustic wave resonator includes a first substrate 100, a main device structure 110 located on the first substrate, and a first support structure 104 surrounding the main device structure 110. The main device structure 110 includes at least a first electrode structure 101, a piezoelectric layer 102, and a second electrode structure 103 stacked sequentially. A first cavity 11 is formed between the first substrate and the main device structure. A second substrate 200 covers the main device structure 110, and a second support structure 201 is disposed on the second substrate 200 facing the main device structure 110. A second cavity 12 is formed between the main device structure 110 and the second substrate 200. The second support structure 201 is bonded to the first support structure 104. A bonding auxiliary structure 300 is located between the first support structure 104 and the second support structure 201, and the bonding auxiliary structure 300 is inserted into the first support structure 104 and / or the second support structure 201.

[0041] The first substrate 100 is used to provide support and protection for the structure within the device. The material of the first substrate 100 may be a single layer or composite film made of any of the following materials: monocrystalline silicon, polycrystalline silicon, silicon oxide, gallium arsenide, sapphire, quartz, silicon carbide, SOI (silicon-on-insulator).

[0042] The first substrate 100 has a first support structure 104 disposed on the side facing the main device structure. Accordingly, the first support structure 104 is used to provide support and protection for the main device structure on the first substrate. The first support structure is also called the first bonding structure. In a specific implementation, the first support structure can form a first cavity together with the first substrate and the main device structure.

[0043] The material of the first support structure 104 can be a single layer or composite film layer made of any of the following materials: monocrystalline silicon, polycrystalline silicon, AlN, silicon oxide, silicon nitride, gallium arsenide, sapphire, quartz, silicon carbide, SOI, and organic support layer. When used as a bonding structure, the material of the first support structure can be a photocurable material, a thermocurable material, or a combination of a photocurable material and a thermocurable material.

[0044] The first electrode structure 101, the piezoelectric layer 102, and the second electrode structure 103 constitute the main structure 110 of the bulk acoustic resonator, used to achieve the corresponding resonant function together with the corresponding acoustic cavity. The first electrode structure 101 and the piezoelectric layer 102 are stacked alternately, and the first support structure 104 can extend below the first electrode structure 101 and the piezoelectric layer 102, thereby providing support for the main structure 110. Thus, the first cavity 11 is formed by the first substrate 100, the first support structure 104, the first electrode structure 101, and the piezoelectric layer 102. In a specific implementation, the portion of the piezoelectric layer 102 exposed in the first cavity can be further provided with a dielectric protective layer, thereby providing isolation protection for the piezoelectric layer 102.

[0045] The overlapping area of ​​the projection of the first electrode structure 101, the piezoelectric layer 102, the second electrode structure 103, and the first cavity 11 can be understood as the effective area 400 of the bulk acoustic resonator, and the area outside the effective area 400 can be called the edge area 410. The first support structure 104 is disposed in the edge area 410.

[0046] In further optional implementations, referencing the reference Figure 2 and Figure 5 ,in, Figure 5 The diagram shown is another example of the integrated acoustic resonator provided by the embodiment of the present invention in cross-sectional view. The first electrode structure 101, piezoelectric layer 102, and second electrode structure 103 completely cover the effective region while extending to the edge region 410 outside the effective region 400 (see figure). Figure 3 The first electrode structure 101, the piezoelectric layer 102, and / or the second electrode structure 103 may extend onto the first support structure 104.

[0047] Specifically, the first electrode structure 101 can extend to the edge region outside the effective region, and the second electrode structure 103 can extend to the edge region on the other side outside the effective region, so that the first electrode structure and the second electrode structure can realize the lead-out of the electrical connection structure based on their respective extended portions; the piezoelectric layer 102 can simultaneously extend to the edge regions on both sides of the effective region. Correspondingly, the first cavity 11 is formed by the first substrate 100, the first support structure 104, the first electrode structure 101, and the piezoelectric layer 102.

[0048] The first support structure can extend from the edge region to the main structure of the device, thereby providing support for the main structure. Alternatively, in other optional implementations, refer to... Figure 6The diagram shown is another example of the integrated acoustic resonator provided by the embodiment of the present invention in cross-sectional view. The first support structure 104 may be located only in the edge region, while in the main structure of the device, the support of the main structure of the device is achieved based on the discrete support block 120. Correspondingly, the first cavity 11 is formed by the first substrate 100, the support block 120, the first electrode structure 101, and the piezoelectric layer 102.

[0049] The first electrode structure can be the bottom electrode of the bulk acoustic wave resonator, and correspondingly, the second electrode structure can be the top electrode of the bulk acoustic wave resonator. The first electrode structure can include a first electrode layer for realizing electrical functions, and the second electrode structure can include a second electrode layer for realizing electrical functions. The materials of the first electrode layer and the second electrode layer can be one or more of molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, and chromium. When multiple materials are present, they can be a composite or alloy of the above materials. The materials of the first electrode layer and the second electrode layer can be the same or different.

[0050] In a further optional implementation, the first electrode structure and the second electrode structure may further include an electrode protective layer. Specifically, the electrode protective layer 105 (only the electrode protective layer in the first electrode structure is shown in the figure) is provided on the side of the first electrode structure opposite to the piezoelectric layer and / or on the side of the second electrode structure opposite to the piezoelectric layer. The material of the electrode protective layer can be an insulating material. The material of the electrode protective layer can be a single layer or a composite film made of any of the following materials: AlN, SiO, Si3N4, SiON, etc.

[0051] The piezoelectric layer is used to convert electrical signals into mechanical vibrations. The material of the piezoelectric layer can be a single-crystal piezoelectric material, a polycrystalline piezoelectric material, or a doped material containing rare earth elements in a certain atomic ratio. When a dielectric protective layer is present, the material of the dielectric protective layer can be one or more of silicon oxide and silicon nitride.

[0052] Among them, single-crystal piezoelectric materials can be 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.; polycrystalline piezoelectric materials can be understood as a material corresponding to single crystal, specifically such as polycrystalline aluminum nitride, zinc oxide, PZT, etc. Alternatively, the piezoelectric layer can be a doped material of the above-mentioned material containing a certain atomic ratio of rare earth elements. For example, the piezoelectric layer can be aluminum nitride doped with at least one rare earth element. Specifically, rare earth elements can be, for example, 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.

[0053] The second substrate 200 provides support and protection for the main structure of the device. The material of the second substrate can be a single layer or composite film made of any of the following materials: monocrystalline silicon, polycrystalline silicon, AlN, silicon oxide, silicon nitride, gallium arsenide, sapphire, quartz, silicon carbide, SOI, and organic support layers. In a specific implementation, the second substrate can be a wafer substrate.

[0054] Correspondingly, a second support structure 201 can also be provided on the side of the second substrate 200 facing the main device structure 110. This second support structure, also called a second bonding structure, provides support and protection for the main device structure on the second substrate. In an optional implementation, the second support structure, together with the second substrate and the main device structure, can form a second cavity 12. The effective area can be the overlapping region of the projections of the first electrode structure 101, the piezoelectric layer 102, the second electrode structure 103, the first cavity 11, and the second cavity 12. In a specific implementation, a dielectric protective layer can also be provided on the portion of the piezoelectric layer 102 exposed in the second cavity, thereby providing isolation and protection for the piezoelectric layer 102.

[0055] The second support structure 201 can be monocrystalline silicon, polycrystalline silicon, silicon oxide, silicon nitride, gallium arsenide, sapphire, quartz, silicon carbide, SOI, and organic support layers, etc. When used as a bonding structure, the material of the second support structure can be a photocurable material, a thermocurable material, or a combination of a photocurable material and a thermocurable material.

[0056] In an example where the first electrode structure 101, the piezoelectric layer 102, and / or the second electrode structure 103 can extend to the edge region, the second support structure is bonded to the first electrode structure 101, the piezoelectric layer 102, and / or the second electrode structure 103 extending to the edge region, thereby making the second support structure connected to the first electrode structure, the piezoelectric layer, or the second electrode structure.

[0057] The second support structure 201 may be located in the edge region, in an example where the first support structure 104 extends below the first electrode structure 101 and the piezoelectric layer 102 (see reference). Figure 3 or Figure 4 The second substrate 200, the second support structure 201, the first support structure 104, and the second electrode structure 103 together form the second cavity 12.

[0058] In a further optional implementation, refer to Figure 5 In the example where the first electrode structure 101, piezoelectric layer 102, and second electrode structure 103 extend to the edge region 410 surrounding the effective region 400, the first electrode structure 101 extends to the edge region on one side of the effective region, the second electrode structure 103 extends to the edge region on the other side of the effective region, and the piezoelectric layer 102 extends to the edge regions on both sides of the effective region. The second substrate 200, the second support structure 201, the piezoelectric layer 102, the first redistribution layer 320, and the second electrode structure 103 together form the second cavity 12.

[0059] In other optional implementations, see reference Figure 6 The first support structure 104 is located only in the edge region, while in the main structure of the device, the main structure of the device is supported by the discrete support block 120. Correspondingly, the second cavity 12 is formed by the second substrate 200, the first substrate 100, the support block 120, the piezoelectric layer 102, the first redistribution layer 320 and the second electrode structure 103.

[0060] In this embodiment of the invention, the bulk acoustic resonator is further provided with a bonding auxiliary structure 300 located between the first support structure 104 and the second support structure 201, the bonding auxiliary structure 300 being inserted into the first support structure 104 (see reference). Figure 3 ) and / or the second support structure 201 (refer to Figure 4 The bonding auxiliary structure surrounds the main structure 110 of the device, thereby improving the sealing of the bonding and enhancing the purity of the signal during the operation of the bulk acoustic wave resonator, thus improving the performance of the device.

[0061] In other alternative examples, the bonding auxiliary structure may surround the main device structure. From a top-view perspective of the bulk acoustic wave resonator, the bonding auxiliary structure may either be closed around the main device structure or not closed around it. When the bonding auxiliary structure is not closed around the main device structure, it may include one or more notches from the top-view perspective of the bulk acoustic wave resonator. The bottom area of ​​the bonding auxiliary structure is smaller than the projected area of ​​the first support structure or the second support structure on the first substrate.

[0062] The bonding aid structure 300 may be located on the first electrode structure, the piezoelectric layer, or the second electrode structure that are connected to the second support structure. Specifically, in an example where the first support structure 104 is directly connected to the second support structure (see reference...),... Figure 3 or Figure 6 The bonding auxiliary structure 300 is located on the first support structure 104 and inserted into the second support structure 201; alternatively, the bonding auxiliary structure may be located on the second support structure and inserted into the first support structure; or, the bonding auxiliary structure may be inserted into both the first and second support structures simultaneously. In a preferred implementation, refer to... Figure 5 The bonding auxiliary structure 300 can be located on the piezoelectric layer 102 connected to the second support structure 201, thereby achieving better device performance.

[0063] Alternatively, in other optional implementations, a first dielectric adhesion layer, a bonding layer, and a second dielectric adhesion layer are sequentially disposed between the first support structure and the second support structure. The bonding auxiliary structure may penetrate the first dielectric adhesion layer and be inserted into the bonding layer; or, the bonding auxiliary structure may penetrate the second dielectric adhesion layer and be inserted into the bonding layer; or, the auxiliary bonding structure may be located between the first dielectric adhesion layer and the second dielectric adhesion layer. The materials of the first dielectric adhesion layer and the second dielectric adhesion layer may be single-layer or composite films made of any of the following materials: AlN, SiO, Si3N4, and SiON.

[0064] The bonding auxiliary structure 300 can be made of a metallic material or an insulating material, wherein the bonding auxiliary structure surrounds the main structure of the device; it is understood that the bonding auxiliary structure further surrounds the main structure of the device, thereby improving the signal shielding performance, enhancing the purity of the signal during filter operation, and further improving the performance of the device.

[0065] When the bonding auxiliary structure is made of a metallic material, the bonding auxiliary structure is disconnected from the main structure of the device or electrically connected to the main structure of the device, for example, electrically connected to the grounding component of the main structure of the device, in order to avoid the electrical influence of the bonding auxiliary structure on the device.

[0066] When the bonding auxiliary structure is made of a metallic material, it can be designed with grounding or heat dissipation. Grounding the bonding auxiliary structure can effectively increase the area of ​​the metal layer, thereby reducing the resonator's resistance while increasing heat dissipation.

[0067] In a further optional implementation, when the bonding auxiliary structure is an insulating material, in the example where the first support structure and the second support structure are directly connected, the material of the bonding auxiliary structure is the same as the material of the first support structure, and the bonding auxiliary structure and the first support structure are an integral structure.

[0068] In specific implementations, to better improve device performance, the bonding aid structure includes multiple parallel auxiliary sub-bump rings (see reference). Figures 2-6 For example, it may include three parallel auxiliary sub-protrusion rings, wherein adjacent auxiliary sub-protrusion rings have an auxiliary spacing of 301 (see reference). Figure 2 The width of the auxiliary interval is a preset interval distance, which is 0.1-10 times the width of the auxiliary sub-protrusion ring, preferably 0.5-2 times.

[0069] It should be noted that the width of the auxiliary sub-protrusion ring can be the dimension within the surface of the first substrate, perpendicular to the extension direction of the auxiliary sub-protrusion ring. In specific implementations, the width of the auxiliary sub-protrusion ring can be greater than or equal to 2μm, for example, it can be 3μm, 4μm, 5μm, or 6μm, etc., and the preset interval distance can also be greater than or equal to 3μm, for example, it can be 4μm, 5μm, or 6μm, etc.

[0070] The auxiliary sub-protrusion ring can be located on the first electrode structure, the piezoelectric layer, or the second electrode structure, respectively, and is connected to the second support structure. When the auxiliary sub-protrusion ring is made of a metallic material, it is fabricated in the same layer as the metallic structure (e.g., the redistribution layer, or the electrode layer in the first or second electrode structure) of the first or second electrode structure. In a specific example, the auxiliary sub-protrusion ring can be made of the same material as the metallic structure in the first electrode structure, and both can be fabricated in the same layer.

[0071] In further optional implementations, refer to Figure 7 and Figure 8 ,in, Figure 7 This is a perspective view of another bulk acoustic resonator provided in an embodiment of the present invention, taken from a top-down perspective. Figure 8 This is a cross-sectional view of another bulk acoustic resonator provided in an embodiment of the present invention. The bonding auxiliary structure 300 may further include a protruding connecting portion 302. The protruding ring connecting portion 302 is located between the auxiliary sub-protruding rings and connected to adjacent auxiliary sub-protruding rings to improve the reliability of the bonding auxiliary structure. In an optional example, refer to... Figure 6The raised ring connecting portion 302 is disposed in the corner region of the bonding auxiliary structure. The corner region is the area with a corner in the bonding auxiliary structure. The corner is the position where the extension direction changes. In a specific implementation, the corner can also be a position where the angle of change in the extension direction is greater than or equal to a preset angle, such as 30°, 45°, or 60°. In a specific example, the raised ring connecting portion 302 and the auxiliary sub-raised ring are an integral structure.

[0072] In a further optional implementation, Figure 9 This is a cross-sectional view of another integrated acoustic resonator provided in an embodiment of the present invention. The main structure of the device further includes a first rewiring layer 320, which is used to realize the electrical connection of the main structure of the device. In a specific implementation, the first rewiring layer 320 can be electrically connected to the second electrode structure 103 to realize the transmission of electrical signals of the second electrode structure.

[0073] Wherein, when the bonding aid structure is a metallic material, reference Figure 9 The bonding auxiliary structure 300 is connected to the first redistribution layer 320 (see the dotted circle in the figure). Specifically, the bonding auxiliary structure is grounded based on the first redistribution layer. In the corresponding device fabrication process, the bonding auxiliary structure can be formed as a co-layer structure with the first redistribution layer, thereby simplifying the process steps.

[0074] In further optional implementations, refer to Figure 8 The bulk acoustic wave resonator may further include: a second redistribution layer 330 located on the side of the first substrate 100 opposite to the main structure of the device, and a via connection portion 340 penetrating the first substrate. The second redistribution layer 330 and the via connection portion 340 are used to realize signal transmission of the main structure of the device.

[0075] The via connection portion 340 is electrically connected to the first rewiring layer 320 and / or the bonding auxiliary structure 300 to the second rewiring layer 330. Specifically, the bonding auxiliary structure can be electrically connected to the first rewiring layer and electrically connected to the second rewiring layer based on the via connection portion connected to the first rewiring layer, or the bonding auxiliary structure can be electrically connected to the via connection portion electrically connected to the second rewiring layer to realize signal transmission of the bonding auxiliary structure.

[0076] For further optional implementations, please refer to [reference needed]. Figure 8The bulk acoustic wave resonator further includes a metal bump structure 350 located on the side of the second rewiring layer 330 opposite to the main structure of the device; the bonding auxiliary structure 300 can be electrically connected to the metal bump structure 350 based on the second rewiring layer 330. Furthermore, in an optional implementation, the first electrode structure can also be electrically connected to the metal bump structure based on a via connection and the second rewiring layer, thereby enabling the introduction and extraction of electrical signals.

[0077] Among them, continue to refer to Figure 8 In the bonding auxiliary structure, the part used to connect to the metal bump structure is provided with a raised ring connection part (at 300 / 302 in the figure), thereby improving the transmission stability of electrical signals.

[0078] As can be seen, the bulk acoustic wave resonator provided in this application embodiment uses a bonding auxiliary structure located on the side of the first substrate facing the second substrate. During the bonding process, the bonding auxiliary structure is inserted into the second support structure adjacent to the second substrate, thereby increasing the bonding contact area at the bonding point, increasing the bonding force, and improving the sealing of the bonding. This prevents moisture from seeping into the device and improves the performance of the device.

[0079] Furthermore, given that the bonding auxiliary structure surrounds the main structure of the device, it improves the signal shielding performance, enhances the purity of the signal during filter operation, and further improves the performance of the device.

[0080] Accordingly, this application also provides a method for forming a bulk acoustic wave resonator, which can be used to obtain the bulk acoustic wave resonator provided in the above embodiments. (Reference) Figures 10 to 18 The illustrated schematic diagram shows the structural steps corresponding to each step in an embodiment of the method for forming a bulk acoustic resonator provided in this application. The method for forming a bulk acoustic resonator may include: refer to Figures 10 to 14 This forms the basic structure of the device.

[0081] The device's basic structure provides a process foundation for subsequent bonding.

[0082] In this embodiment of the application, the device base structure may include a first substrate, a main device structure located on the first substrate, and a first support structure surrounding the main device structure. The main device structure includes at least a first electrode structure, a piezoelectric layer, and a second electrode structure stacked in sequence, and a first cavity is provided between the first substrate and the main device structure.

[0083] The first substrate 500 is used to provide support and protection for the structure within the device. The material of the first substrate 500 may be a single layer or composite film made of any of the following materials: single crystal silicon, gallium arsenide, sapphire, quartz, silicon carbide, SOI (silicon-on-insulator), silicon nitride, aluminum nitride, silicon oxide, etc.

[0084] A first support structure is formed on the side of the first substrate facing the main device structure. Accordingly, the first support structure is used to provide support and protection for the main device structure on the first substrate. The first support structure is also called a first bonding structure. In a specific example, the first support structure can form a first cavity together with the first substrate and the main device structure.

[0085] The material of the first support structure can be monocrystalline silicon, polycrystalline silicon, silicon oxide, silicon nitride, gallium arsenide, sapphire, quartz, silicon carbide, SOI, and organic support layers, etc. When used as a bonding structure, the material of the first support structure can be a photocurable material, a thermocurable material, or a combination of a photocurable material and a thermocurable material.

[0086] The first electrode structure 501, the piezoelectric layer 502, and the second electrode structure 503 constitute the main structure of the bulk acoustic resonator, used to achieve the corresponding resonant function together with the corresponding acoustic cavity. The first electrode structure 501 and the piezoelectric layer 502 are stacked alternately, and the first support structure can extend below the first electrode structure and the piezoelectric layer, thereby simultaneously providing support for the main structure of the device. Thus, a first cavity is formed by the first substrate, the first support structure, the first electrode structure, and the piezoelectric layer. In a specific implementation, a dielectric protective layer can be provided on the portion of the piezoelectric layer 502 exposed in the first cavity, thereby providing isolation and protection for the piezoelectric layer 502.

[0087] The overlapping region of the projection of the first electrode structure 501, the piezoelectric layer 502, the second electrode structure 503, and the first cavity can be understood as the effective region of the bulk acoustic resonator, and the region outside the effective region can be called the edge region.

[0088] In a further optional implementation, the first electrode structure, piezoelectric layer, and second electrode structure completely cover the effective region and can extend to the edge region surrounding the effective region. The first electrode structure, piezoelectric layer, and / or the second electrode structure can extend onto the first support structure.

[0089] Specifically, the first electrode structure can extend to the edge region on one side of the effective region, and the second electrode structure can extend to the edge region on the other side of the effective region, thereby enabling the first electrode structure and the second electrode structure to achieve the lead-out of the electrical connection structure based on their respective extended portions; the piezoelectric layer can simultaneously extend to the edge regions on both sides of the effective region. Correspondingly, the first cavity is formed by the first substrate, the first support structure, the first electrode structure, and the piezoelectric layer.

[0090] In other alternative implementations, the first support structure may be located only in the edge region, while in the main structure of the device, the support for the main structure of the device is achieved based on discrete support blocks. Correspondingly, the first cavity is formed by the first substrate, the support blocks, the first electrode structure, and the piezoelectric layer.

[0091] The first electrode structure can be the bottom electrode of the bulk acoustic wave resonator, and correspondingly, the second electrode structure can be the top electrode of the bulk acoustic wave resonator. Both the first and second electrode structures can include electrode layers for realizing electrical functions (e.g., a first electrode layer located in the first bottom electrode structure and a second electrode layer located in the second electrode structure). The material of the electrode layers can be one or more of molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, and chromium. When multiple materials are present, they can be composites or alloys of the above materials. The electrode layer materials of the first and second electrode structures can be the same or different. The first and second electrode structures may further include an electrode protective layer, specifically, the material of the electrode protective layer can be an insulating material.

[0092] The piezoelectric layer is used to convert electrical signals into mechanical vibrations. The material of the piezoelectric layer can be a single-crystal piezoelectric material, a polycrystalline piezoelectric material, or a doped material containing rare earth elements in a certain atomic ratio.

[0093] Among them, single-crystal piezoelectric materials can be 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.; polycrystalline piezoelectric materials can be understood as a material corresponding to single crystal, specifically such as polycrystalline aluminum nitride, zinc oxide, PZT, etc. Alternatively, the piezoelectric layer can be a doped material of the above-mentioned material containing a certain atomic ratio of rare earth elements. For example, the piezoelectric layer can be aluminum nitride doped with at least one rare earth element. Specifically, rare earth elements can be, for example, 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.

[0094] In an optional example, the process of forming the device infrastructure may include: refer to Figure 10 Provide temporary substrate 800; The temporary substrate 800 serves as a carrier to support the main device structure of the bulk acoustic wave resonator subsequently formed on the temporary substrate 800. The main device structure may include, for example, a first electrode structure, a piezoelectric layer, and a second electrode structure. After the corresponding main device structure is formed on the temporary substrate, the temporary substrate can be removed.

[0095] The temporary substrate can be made of materials such as single-crystal silicon, gallium arsenide, sapphire, quartz, silicon carbide, SOI (Silicon-On-Insulator), etc.

[0096] refer to Figure 11 A second electrode structure material layer 401, a piezoelectric material layer 402, and a first electrode structure material layer are sequentially stacked on the temporary substrate 800. The first electrode structure material layer is used to form the first electrode structure, which can serve as either a bottom electrode or a top electrode. In this step, the first electrode structure is described as a bottom electrode. The first electrode structure may include a first electrode layer for realizing electrical functions. Accordingly, the first electrode structure material layer may include a first electrode material layer 403 for forming the first electrode layer.

[0097] The first electrode material layer 403 can be one or more of molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, and chromium. When multiple materials are present, it can be a composite or alloy of the above materials. In a specific example, the first electrode material layer can be formed based on a deposition process or an electroplating process. In subsequent steps, the first electrode material layer can be patterned based on an etching process to form a first electrode layer with a specific morphology.

[0098] In a further implementation, the first electrode structure may further include an electrode protective layer, and correspondingly, the first electrode structure material layer may further include an electrode protective material layer (not shown in the figure) for forming the electrode protective layer.

[0099] The piezoelectric material layer 402 is used to form the piezoelectric layer. The material of the piezoelectric material layer can be a single-crystal piezoelectric material, a polycrystalline piezoelectric material, or a doped material containing a certain atomic ratio of rare earth elements. In a specific example, the piezoelectric material layer can be formed based on a deposition process or a growth process.

[0100] The second electrode structure material layer 401 is used to form a second electrode structure, which can serve as either a top electrode or a bottom electrode. In this step, the second electrode structure is described as a top electrode. The second electrode structure may include a second electrode layer for realizing electrical functions. Correspondingly, the second electrode structure material layer may include a second electrode material layer for forming the second electrode layer.

[0101] The second electrode material layer can be one or more of molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, and chromium. When multiple materials are present, it can be a composite or alloy of the above materials. In a specific example, the second electrode material layer can be formed based on a combination of deposition or electroplating processes and etching or lift-off processes. In subsequent steps, the second electrode material layer can be patterned based on an etching process to form a second electrode layer with a specific morphology.

[0102] It should be noted that in this step, a second electrode structure material layer is first formed on a temporary substrate, and then a piezoelectric material layer and a first electrode structure material layer are formed in sequence. This results in the first electrode structure material layer for forming the bottom electrode being formed on the piezoelectric material layer and the first electrode structure material layer for forming the top electrode. In subsequent steps, the main structure formed on the temporary substrate is flipped onto the first substrate, so that the relative position of the first electrode structure becomes below the piezoelectric layer and the second electrode structure, thus serving as the bottom electrode of the device.

[0103] In a further implementation, the second electrode structure may further include an electrode protective layer, and correspondingly, the first electrode structure material layer may further include an electrode protective material layer (not shown in the figure) for forming the electrode protective layer.

[0104] In a further optional implementation, a seed layer may be further formed on the temporary substrate, the seed layer being located between the temporary substrate and the second electrode structure material layer.

[0105] refer to Figure 12The first electrode structure material layer is graphically represented, and the remaining first electrode structure material layer is used as the first electrode structure 501. In this process, the first electrode material layer 403 in the first electrode structure material layer is patterned to form the first electrode layer. In an optional implementation, when an electrode protective material layer is present, an electrode protective layer 505 can be formed simultaneously based on the patterning; or, when an electrode protective material layer is absent, this step can further form the electrode protective layer 505 after forming the first electrode layer.

[0106] Next, refer to Figure 13 A first substrate 500 is provided and bonded to the side of the temporary substrate where the first electrode structure is provided, wherein a first cavity 11 is formed between the first substrate 500 and the first electrode structure; The first substrate 500 provides support and protection for the main structure of the device. In an optional example, when the first substrate 500 serves as a bottom substrate, a first support structure 504 can be formed on the temporary substrate facing the first electrode structure before this step. This allows a receiving space to be formed between the first support structure 504, the first electrode structure, and the first substrate. After bonding, the first substrate 500 forms a first cavity 11 based on the first support structure 504 and the temporary substrate on the side where the first electrode structure is located. In a specific implementation, the portion of the piezoelectric layer 502 exposed in the first cavity can be further formed with a dielectric protective layer, thereby providing isolation and protection for the piezoelectric layer 502.

[0107] In an optional example, while the first support structure 504 is formed on the side of the temporary substrate facing the first electrode structure, a support block 510 can also be formed simultaneously to provide support for the main structure of the device.

[0108] In this step, the temporary substrate can be further removed; In an optional example, the temporary substrate can be removed by grinding, thereby exposing the second electrode structure material layer.

[0109] It is understood that after removing the temporary substrate, the device structure can be flipped so that the first substrate and the first electrode structure serve as the bottom surface of the device, and the material layer of the second electrode structure faces upward.

[0110] refer to Figure 14 The second electrode structure material layer and the piezoelectric material layer are graphically represented to form the second electrode structure 503 and the piezoelectric layer 502. In conjunction with the aforementioned description of the bulk acoustic resonator, the projected overlapping area of ​​the first electrode structure, the piezoelectric layer 502, the second electrode structure 503, and the first cavity 11 can be defined as the effective region, and the area outside the effective region is the edge region.

[0111] In an optional implementation, the second electrode structure 503 and the piezoelectric layer 502 can be patterned based on multiple patterning processes. For example, the patterning of the second electrode structure 503 can be performed in one patterning process, the patterning of the piezoelectric layer 502 can be performed in one patterning process, and the patterning of a specific pattern of the second electrode structure can be performed in one patterning process.

[0112] Further reference Figure 15 A substrate pre-bonding structure is formed, the substrate pre-bonding structure including a second substrate 700 and a second support structure 701 located on the second substrate 700; The second substrate 700 is used to provide support and protection for the main structure of the device. The material of the second substrate can be a single layer or composite film made of any of the following materials: single-crystal silicon, gallium arsenide, sapphire, quartz, silicon carbide, SOI, etc.

[0113] The second support structure 701, also known as the second bonding structure, provides support and protection for the main device structure on the second substrate. In subsequent steps, the second support structure, after bonding, can enclose the second substrate 700 and the main device structure to form a second cavity 12. Specifically, in a concrete implementation, a dielectric protective layer can also be provided on the portion of the piezoelectric layer exposed in the second cavity to provide isolation and protection for the piezoelectric layer.

[0114] The second support structure 701 can be monocrystalline silicon, polycrystalline silicon, silicon oxide, silicon nitride, gallium arsenide, sapphire, quartz, silicon carbide, SOI, and organic support layers, etc. When used as a bonding structure, the material of the second support structure can be a photocurable material, a thermocurable material, or a combination of a photocurable material and a thermocurable material.

[0115] The substrate pre-bonding structure can be formed by forming a second support structure on the second substrate.

[0116] It is understandable that after forming the basic device structure or substrate pre-bonding structure, bonding auxiliary structures can be further formed. For details, please refer to... Figure 16 A bonding auxiliary structure is formed on the side of the first support structure 504 opposite to the first substrate 500; The bonding auxiliary structure 600 surrounds the main structure of the device.

[0117] The bonding auxiliary structure 600 is used to be inserted into the first support structure or the second support structure as part of the bonding surface during subsequent bonding processes, thereby increasing the bonding contact area at the bonding point and increasing the bonding force.

[0118] In a specific implementation, a bonding aid structure is formed in the edge region. Specifically, in the implementation where the bonding aid structure is formed on the side of the first support structure 504 opposite to the first substrate 500, when the edge region of the first substrate facing the main device structure is a first electrode structure, a bonding aid structure is formed on the first electrode structure in that region; when the edge region of the first substrate facing the main device structure is a pressure electrode, a bonding aid structure is formed on the pressure electrode in that region; and when the edge region of the first substrate facing the main device structure is a second electrode structure, a bonding aid structure is formed on the second electrode structure in that region. Further, when the edge region of the first substrate facing the main device structure is a first support structure (refer to...),... Figure 16 A bonding auxiliary structure is formed on the first support structure in this region.

[0119] The bonding auxiliary structure 600 can be made of a metallic material or an insulating material. When the bonding auxiliary structure is made of a metallic material, it is disconnected from the main structure of the device or electrically connected to the grounding component of the main structure of the device, thereby avoiding the electrical influence of the bonding auxiliary structure on the device.

[0120] When the bonding auxiliary structure is made of a metallic material, it can be designed with grounding or heat dissipation. Grounding the bonding auxiliary structure can effectively increase the area of ​​the metal layer, thereby reducing the resonator's resistance while increasing heat dissipation.

[0121] In a further optional implementation, when the bonding auxiliary structure is an insulating material, in the example where the first support structure and the second support structure are directly connected, the material of the bonding auxiliary structure is the same as the material of the first support structure, and the bonding auxiliary structure and the first support structure are an integral structure.

[0122] In the example where the bonding auxiliary structure and the first support structure are integral, the bonding auxiliary structure can be formed by etching the first support structure.

[0123] In a specific implementation, to better improve device performance, the bonding auxiliary structure includes multiple parallel auxiliary sub-bump rings, for example, it may include three parallel auxiliary sub-bump rings, wherein there is an auxiliary interval 601 between adjacent auxiliary sub-bump rings, the width of the auxiliary interval is a preset interval distance, and the preset interval distance is 0.5-2 times the width of the auxiliary sub-bump ring.

[0124] It should be noted that the width of the auxiliary sub-protrusion ring can be the dimension within the surface of the first substrate, perpendicular to the extension direction of the auxiliary sub-protrusion ring. In specific implementations, the width of the auxiliary sub-protrusion ring can be greater than or equal to 3μm, for example, it can be 4μm, 5μm, or 6μm, etc., and the preset interval distance can also be greater than or equal to 3μm, for example, it can be 4μm, 5μm, or 6μm, etc.

[0125] The auxiliary sub-protrusion ring may be located on the first electrode structure, the piezoelectric layer, or the second electrode structure that are connected to the second support structure.

[0126] In a further optional implementation, the bonding aid structure 600 may further include a protruding connecting portion, wherein the protruding ring connecting portion is located between the auxiliary sub-protruding rings and connected to adjacent auxiliary sub-protruding rings, thereby improving the reliability of the bonding aid structure. In an optional example, the protruding ring connecting portion is disposed in the corner region of the bonding aid structure. The corner region is a region in the bonding aid structure that has a corner. In a specific example, the protruding ring connecting portion and the auxiliary sub-protruding ring are an integral structure.

[0127] In an optional example, after forming the second electrode structure 503 and the piezoelectric layer 502, a first redistribution layer may be further formed to achieve electrical connection of the corresponding structure.

[0128] Specifically, in the method for forming the bulk acoustic wave resonator, after forming the basic device structure, the method further includes forming a first redistribution layer 620 on the side of the first substrate facing the main device structure. When the bonding auxiliary structure is a metallic material, the bonding auxiliary structure 600 can be formed simultaneously with the first redistribution layer 620.

[0129] It should be noted that when the bonding auxiliary structure is fabricated in the same layer as the bottom electrode, it can form a morphology of embedding the first support structure, and when it is fabricated in the same layer as the first redistribution layer, it can form a morphology of embedding the second support structure.

[0130] Further reference Figure 17 The substrate pre-bonding structure is bonded to the device base structure, wherein the bonding auxiliary structure 600 is inserted into the second support structure 701; After bonding, the second support structure 701 can be combined with the second substrate 700 and the main device structure to form a second cavity 12.

[0131] The second support structure 701 may be located in the edge region. In the example where the first electrode structure 501, the piezoelectric layer 502, and / or the second electrode structure 503 may extend to the edge region, the second support structure is bonded to the first electrode structure 501, the piezoelectric layer 502, and / or the second electrode structure 503 extending to the edge region, thereby making the second support structure connected to the first electrode structure, the piezoelectric layer, or the second electrode structure.

[0132] It should be noted that the bonding described in this step can be understood as a wafer-level packaging process.

[0133] Given that the bonding auxiliary structure 600 is inserted into the second support structure 701 and surrounds the main structure of the device, the bonding sealing is improved while the purity of the signal during the operation of the bulk acoustic resonator is enhanced, thereby improving the performance of the device.

[0134] In some alternative implementations, the bonding aid structure can be fabricated in the same layer as the first electrode layer (i.e., the metal structure of the first electrode structure) or the metal structure of the second electrode structure. That is, when forming the first electrode structure material layer or the second electrode structure material layer, the corresponding layer structure simultaneously covers the region used to form the bonding aid structure, and then the bonding aid structure is synchronously formed in this region based on patterning processing.

[0135] Further reference Figure 18 A via connection portion 740 is formed that penetrates the first substrate 500, and a second redistribution layer 730 and a metal bump structure 750 are connected to the via connection portion 740. The via connection portion 740 is used to electrically connect the first rewiring layer 620 and / or the bonding auxiliary structure 600 to the second rewiring layer 730. The second rewiring layer 730 and the via connection portion 740 are used to realize signal transmission of the main structure of the device. The metal bump structure 750 is used to realize the electrical connection between the internal structure and the external structure of the device. In a specific implementation, the via connection portion 740 can be further electrically connected to the first electrode structure 501 and further electrically connected to the first rewiring layer 620.

[0136] The via connection portion 740 is electrically connected to the first rewiring layer 620 and / or the bonding auxiliary structure 600 to the second rewiring layer 730. Specifically, the bonding auxiliary structure can be electrically connected to the first rewiring layer and electrically connected to the second rewiring layer based on the via connection portion connected to the first rewiring layer, or the bonding auxiliary structure can be electrically connected to the via connection portion electrically connected to the second rewiring layer to realize signal transmission of the bonding auxiliary structure.

[0137] The bulk acoustic wave resonator formed in this application embodiment uses a bonding auxiliary structure located on the side of the first substrate facing the second substrate. During the bonding process, the bonding auxiliary structure is inserted into the second support structure adjacent to the second substrate, thereby increasing the bonding contact area at the bonding point, increasing the bonding force, and improving the sealing of the bonding. This prevents moisture from seeping into the device and improves the device performance.

[0138] Furthermore, given that the bonding auxiliary structure surrounds the main structure of the device, it improves the signal shielding performance, enhances the purity of the signal during filter operation, and further improves the performance of the device.

[0139] This application also provides a filter, including the bulk acoustic resonator as described in the above embodiments.

[0140] This application also provides a communication device, including the filter described in the above embodiments.

[0141] This application also provides a terminal, including the filter described in the above embodiments.

[0142] The foregoing describes multiple embodiment schemes provided by the embodiments of this application. The optional methods described in each embodiment scheme can be combined and cross-referenced with each other without conflict, thereby extending to a variety of possible embodiment schemes. These can all be considered as the embodiment schemes disclosed and published by the embodiments of this application.

[0143] While the embodiments disclosed above are described in this application, this application is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of this application; therefore, the scope of protection of this application should be determined by the scope defined in the claims.

Claims

1. A bulk acoustic resonator, characterized in that, include: A first substrate, and a device main structure located on the first substrate and a first support structure surrounding the device main structure, wherein the device main structure includes at least a first electrode structure, a piezoelectric layer and a second electrode structure stacked in sequence, and a first cavity is provided between the first substrate and the device main structure. A second substrate covering the main structure of the device, and a second support structure disposed on the second substrate facing the main structure of the device; The main structure of the device has a second cavity between it and the second substrate, and the second support structure is bonded to the first support structure. A bonding auxiliary structure is located between the first support structure and the second support structure, the bonding auxiliary structure being inserted into the first support structure and / or the second support structure.

2. The bulk acoustic resonator according to claim 1, characterized in that, The bonding auxiliary structure is made of a metallic material or an insulating material, and the bonding auxiliary structure surrounds the main structure of the device; when the bonding auxiliary structure is made of a metallic material, the bonding auxiliary structure is disconnected from the main structure of the device or electrically connected to the main structure of the device. From the top view of the bulk acoustic resonator, the bonding auxiliary structure either surrounds the main structure of the device in a closed manner, or the bonding auxiliary structure does not surround the main structure of the device in a closed manner.

3. The bulk acoustic resonator according to claim 1, characterized in that, The first support structure is connected to the second support structure, and the bonding auxiliary structure is located on the first support structure and inserted into the second support structure; or, the bonding auxiliary structure is located on the second support structure and inserted into the first support structure; or, the bonding auxiliary structure is inserted into both the first support structure and the second support structure. Alternatively, a first dielectric adhesion layer, a bonding layer, and a second dielectric adhesion layer may be sequentially disposed between the first support structure and the second support structure, with the bonding auxiliary structure penetrating through the first dielectric adhesion layer and inserted into the bonding layer; or, the bonding auxiliary structure may penetrate through the second dielectric adhesion layer and be inserted into the bonding layer.

4. The bulk acoustic resonator according to any one of claims 1 to 3, characterized in that, The bonding aid structure includes multiple parallel auxiliary sub-protrusion rings, with an auxiliary interval between adjacent auxiliary sub-protrusion rings. The width of the auxiliary interval is a preset interval distance, which is 0.1-10 times the width of the auxiliary sub-protrusion ring.

5. The bulk acoustic resonator according to claim 4, characterized in that, The bonding auxiliary structure further includes a raised ring connecting portion, which is located between the auxiliary sub-raised rings and connected to the adjacent auxiliary sub-raised rings.

6. The bulk acoustic resonator according to claim 5, characterized in that, The raised ring connecting portion is located in the corner area of ​​the bonding auxiliary structure.

7. The bulk acoustic resonator according to claim 1 or 2, characterized in that, The main structure of the device also includes a first wiring layer, and the bonding auxiliary structure is connected to the first wiring layer.

8. The bulk acoustic resonator according to claim 7, characterized in that, Also includes: A second wiring layer located on the side of the first substrate away from the main structure of the device, and a via connection portion penetrating the first substrate; The via connection portion electrically connects the first wiring layer and / or the bonding auxiliary structure to the second wiring layer.

9. The bulk acoustic resonator according to claim 8, characterized in that, Also includes: A metal bump structure located on the side of the second redistribution layer opposite to the main structure of the device; The bonding aid structure is electrically connected to the metal bump structure based on the second rewiring layer; In the bonding auxiliary structure, the portion used to connect to the metal bump structure is provided with a raised ring connecting part.

10. The bulk acoustic resonator according to claim 2, characterized in that, Between the first support structure and the second support structure, the second support structure is connected to the first electrode structure, connected to the piezoelectric layer, or connected to the second electrode structure; The bonding auxiliary structure is located on the first electrode structure, the piezoelectric layer, or the second electrode structure that is connected to the second support structure; Wherein, the bottom area of ​​the bonding auxiliary structure is smaller than the projected area of ​​the first support structure or the second support structure on the first substrate.

11. The bulk acoustic resonator according to claim 4, characterized in that, When the auxiliary protrusion ring is made of a metallic material, the auxiliary protrusion ring is fabricated in the same layer as the metallic structure in the first electrode structure or the second electrode structure.

12. The bulk acoustic resonator according to claim 2, characterized in that, The bonding auxiliary structure is made of the same material as the first support structure, and the bonding auxiliary structure and the first support structure are an integral structure.

13. A method for forming a bulk acoustic resonator, used to form a bulk acoustic resonator as described in any one of claims 1-12, characterized in that, include: A device base structure is formed, the device base structure including a first substrate, a main device structure located on the first substrate and a first support structure surrounding the main device structure, the main device structure including at least a first electrode structure, a piezoelectric layer and a second electrode structure stacked in sequence, and a first cavity between the first substrate and the main device structure; A substrate prebonding structure is formed, the substrate prebonding structure including a second substrate and a second support structure located on the second substrate; A bonding auxiliary structure is formed on the side of the first support structure opposite to the first substrate or on the side of the second support structure opposite to the second substrate; The substrate pre-bonding structure is bonded to the device base structure, wherein the bonding auxiliary structure is inserted into the second support structure and / or the first support structure.

14. A filter, characterized in that, include: The bulk acoustic resonator as described in any one of claims 1-12.

15. A communication device, characterized in that, include: The filter as described in claim 14.

16. A terminal, characterized in that, include: The filter as described in claim 15.

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