Method for manufacturing acoustic wave device and acoustic wave device

Abstract

An embodiment of the present disclosure discloses a method for manufacturing an acoustic wave device and an acoustic wave device. The acoustic wave device includes a resonant structure. The method includes: forming a connection layer around a device area on a substrate surface, where the device area is used to dispose the resonant structure; forming a conductive support structure on the surface of the connection layer, where the height of the support structure is greater than the height of the resonant structure; forming a packaging layer covering the device area on the top of the support structure, where the packaging layer, the support structure, the connection layer, and the substrate form a sealed cavity around the device area.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to the field of acoustic wave devices, and particularly to a manufacturing method and an acoustic wave device of an acoustic wave device. Background Art

[0002] Since acoustic waves will undergo total reflection when encountering the air or vacuum interface and reflect back the energy without loss, acoustic wave devices such as filters designed using acoustic wave technology have extremely excellent performance and are widely used in communication devices such as mobile phones.

[0003] To obtain the required air or vacuum interface, wafer-level packaging technology is required for acoustic wave devices. In related technologies, an acoustic wave device wafer-level packaging structure is usually prepared by the following method: providing a carrier wafer and a capping wafer, placing the acoustic wave device on the carrier wafer, and performing a hollowing process at the position of the capping wafer corresponding to the acoustic wave device; then, placing bonding materials on the carrier wafer and the capping wafer, and bonding the carrier wafer and the capping wafer in a high-temperature and vacuum environment to form a sealed cavity; after that, using the Through Silicon Via (TSV) technology to lead out the pins. However, due to the extremely complex implementation processes of wafer bonding and TSV technology, high precision requirements for equipment and processes, and expensive manufacturing costs, the preparation process of the acoustic wave device wafer-level packaging structure becomes cumbersome, complex, and costly.

[0004] In summary, how to reduce the manufacturing cost of the acoustic wave device wafer-level packaging structure while improving the packaging quality of the acoustic wave device has become an urgent problem to be solved. Summary of the Invention

[0005] In view of this, embodiments of the present disclosure provide a manufacturing method and an acoustic wave device of an acoustic wave device.

[0006] According to the first aspect of the embodiments of the present disclosure, a manufacturing method of an acoustic wave device is provided. The acoustic wave device includes a resonant structure, and the method includes:

[0007] Forming a wiring layer surrounding the device area on the surface of the substrate; wherein, the device area is used to arrange the resonant structure;

[0008] Forming a conductive support structure on the surface of the wiring layer; wherein, the height of the support structure is greater than the height of the resonant structure;

[0009] Forming a packaging layer covering the device area on the top of the support structure; wherein, the packaging layer, the support structure, the wiring layer, and the substrate form a sealed cavity surrounding the device area.

[0010] In some embodiments, before forming the support structure, the method further includes:

[0011] forming a first sacrificial layer, a first electrode layer covering the first sacrificial layer, a piezoelectric layer covering the first electrode layer, a second electrode layer covering the piezoelectric layer, and an adjustment layer covering the second electrode layer in sequence in the device region;

[0012] After forming the support structure and before forming the support layer, the method further includes:

[0013] removing the first sacrificial layer, forming a first cavity between the first electrode layer and the substrate surface based on the morphology of the first sacrificial layer to form a reflective structure of the resonant structure; trimming the adjustment layer.

[0014] In some embodiments, before forming the support structure, the method further includes:

[0015] etching the substrate surface in the device region to form a groove on the substrate surface; forming a second sacrificial layer filling the groove; forming a first electrode layer covering the second sacrificial layer, a piezoelectric layer covering the first electrode layer, a second electrode layer covering the piezoelectric layer, and an adjustment layer covering the second electrode layer in sequence;

[0016] After forming the support structure and before forming the support layer, the method further includes:

[0017] removing the second sacrificial layer, forming a second cavity between the first electrode layer and the substrate surface based on the morphology of the second sacrificial layer to form a reflective structure of the resonant structure; trimming the adjustment layer.

[0018] In some embodiments, before forming the support structure, the method further includes:

[0019] forming the reflective structure of the resonant structure, a first electrode layer covering the reflective structure, a piezoelectric layer covering the first electrode layer, a second electrode layer covering the piezoelectric layer, and an adjustment layer covering the second electrode layer in sequence in the device region of the substrate surface; trimming the adjustment layer.

[0020] According to a second aspect of the embodiments of the present disclosure, there is provided an acoustic wave device, including:

[0021] a substrate;

[0022] a resonant structure located on the substrate surface;

[0023] a connection layer surrounding the resonant structure located on the substrate surface;

[0024] A conductive support structure, located on the surface of the wiring layer and surrounding the resonant structure; wherein, the height of the support structure is greater than the height of the resonant structure;

[0025] An encapsulation layer, located on top of the support structure and covering the resonant structure;

[0026] Wherein, the resonant structure is located in a sealed cavity formed by the encapsulation layer, the support structure, the wiring layer, and the substrate.

[0027] In some embodiments, the resonant structure includes:

[0028] A reflection structure, a first electrode layer, an adjustment layer, a second electrode layer, and an adjustment layer that are sequentially stacked; wherein, the reflection structure is located between the first electrode layer and the surface of the substrate.

[0029] In some embodiments, the reflection structure includes:

[0030] A first cavity, located between the first electrode layer and the surface of the substrate;

[0031] The first cavity is formed by removing a first sacrificial layer located between the surface of the substrate and the first electrode layer after forming the support structure and before forming the encapsulation layer;

[0032] Or,

[0033] The first cavity is formed by removing a sacrificial layer located between the surface of the substrate and the first electrode layer before forming the support structure.

[0034] In some embodiments, the reflection structure includes:

[0035] A second cavity formed by the surface of the substrate being recessed downward, located between the first electrode layer and the surface of the substrate;

[0036] The second cavity is formed by removing a second sacrificial layer filled in a groove recessed downward on the surface of the substrate after forming the support structure and before forming the encapsulation layer;

[0037] Or,

[0038] The second cavity is formed by removing a second sacrificial layer filled in a groove recessed downward on the surface of the substrate before forming the support structure.

[0039] In some embodiments, the reflection structure includes:

[0040] A first dielectric layer and a second dielectric layer are alternately stacked; wherein the acoustic impedance of the first dielectric layer is different from the acoustic impedance of the second dielectric layer.

[0041] In some embodiments, the supporting structure is made of a material including: metal or metal alloy.

[0042] The disclosed embodiment forms a conductive support structure on the wiring layer on the surface of the substrate, and forms a packaging layer on top of the support structure to form the sealed cavity, thereby completing the packaging of the acoustic wave device. The process is simple and there is no need to use wafer bonding and TSV technology, which simplifies the packaging process for the acoustic wave device and reduces the packaging cost.

[0043] Furthermore, when the acoustic wave device is packaged by a wafer bonding process, for an acoustic wave device including a cavity, the stress released during the bonding process may cause the cavity to collapse. The disclosed embodiment does not require the use of a wafer bonding process, thereby reducing the risk of cavity collapse in the acoustic wave device, reducing the restrictions on the manufacturing method due to the wafer bonding process, and increasing the flexibility of the manufacturing method.

[0044] In addition, the present invention forms a conductive support structure on the wiring layer and adopts a connected structure formed by the wiring layer and the support structure as a path for transmitting electrical signals. Compared with only using the wiring layer as the path for transmitting electrical signals, the thickness of the path for transmitting electrical signals is increased and the resistance of the path is reduced, thereby reducing the electrical loss of the acoustic wave device, which is beneficial to improving the electrical performance of the acoustic wave device. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 is a flow chart of a method for manufacturing an acoustic wave device according to an exemplary embodiment;

[0046] Figures 2a to 2d is a schematic diagram of a method for manufacturing an acoustic wave device according to an exemplary embodiment;

[0047] Figure 3 is a schematic diagram of an acoustic wave device according to an exemplary embodiment. DETAILED DESCRIPTION

[0048] The technical solution of the present disclosure will be further described in detail below in conjunction with the accompanying drawings and embodiments. Although the exemplary implementation methods of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the implementation methods described here. On the contrary, these implementation methods are provided in order to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0049] The present invention will be described more specifically by way of example with reference to the accompanying drawings in the following paragraphs. The advantages and features of the present disclosure will become clearer based on the following description and the claims. It should be noted that the accompanying drawings are in very simplified forms and use non-precise scales, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present disclosure.

[0050] In the embodiments of the present disclosure, the term "A is connected to B" includes the situation where A and B are connected to each other in contact, or the situation where A is non-contact connected to B with other components interposed between A and B.

[0051] In the embodiments of the present disclosure, terms such as "first", "second", etc. are used to distinguish similar objects, and do not necessarily describe a specific order or sequence.

[0052] It should be noted that the technical solutions described in the embodiments of the present invention can be combined arbitrarily without conflict.

[0053] Figure 1 is a flowchart of a manufacturing method of an acoustic wave device according to an exemplary embodiment, and the acoustic wave device includes a resonant structure. Refer to Figure 1 As shown, the method includes the following steps:

[0054] S100: Form a wiring layer around the device area on the surface of the substrate; wherein, the device area is used to arrange the resonant structure;

[0055] S110: Form a conductive support structure on the surface of the wiring layer; wherein, the height of the support structure is greater than the height of the resonant structure;

[0056] S120: Form a packaging layer covering the device area on the top of the support structure; wherein, the packaging layer, the support structure, the wiring layer and the substrate form a sealed cavity around the device area.

[0057] The resonant structure may include: a bulk acoustic wave (BAW) resonant element. For example, a thin film bulk acoustic wave resonator (FBAR) and / or a solid mounted resonator (SMR).

[0058] In S110, a conductive support structure can be formed on the surface of the wiring layer by electroplating or vacuum coating.

[0059] The constituent material of the support structure may include a metal or an alloy, such as aluminum, tungsten, copper, molybdenum or an aluminum alloy, etc.

[0060] The encapsulation layer is used to shield and protect the resonance region of the resonant structure. Since the height of the support structure is greater than that of the resonant structure, there is a gap between the encapsulation layer and the resonance region of the resonant structure, and this gap can be used to reflect sound waves.

[0061] The constituent material of the encapsulation layer may include a layered structure capable of being used for encapsulation, such as a dry film, etc.

[0062] In the embodiment of the present disclosure, by forming a support structure with a height greater than that of the resonant structure, there is a gap between the encapsulation layer located at the top of the support structure and the resonance region of the resonant structure, that is, the encapsulation layer and the resonance region of the resonant structure do not come into direct contact, which can avoid the influence on the resonance frequency of the resonant structure due to the direct contact between the encapsulation layer and the resonance region of the resonant structure, facilitating ensuring that the set accuracy of the resonance frequency of the formed resonant structure is relatively good, and further ensuring better performance of the acoustic wave device.

[0063] In the embodiment of the present disclosure, by forming a conductive support structure on the wiring layer on the substrate surface and forming an encapsulation layer on the top of the support structure to form the sealed cavity, the encapsulation of the acoustic wave device can be completed, and the process is simple, without the need to adopt wafer bonding and TSV technologies, simplifying the encapsulation process for the acoustic wave device and reducing the encapsulation cost.

[0064] Moreover, when the wafer bonding process is used to encapsulate the acoustic wave device, for an acoustic wave device including a cavity, the stress released during the bonding process will cause the cavity to collapse. The embodiment of the present disclosure does not need to adopt the wafer bonding process, reducing the risk of cavity collapse in the acoustic wave device, reducing the limitations on the manufacturing method due to the wafer bonding process, and increasing the flexibility of the manufacturing method.

[0065] In addition, in the present disclosure, by forming a conductive support structure on the wiring layer and using the conductive thick film formed by the wiring layer and the support structure together as the path for transmitting electrical signals, compared with using only the wiring layer as the path for transmitting electrical signals, the thickness of the path for transmitting electrical signals is increased, the resistance of this path is reduced, and thus the electrical loss of the acoustic wave device is reduced, which is beneficial to improving the electrical performance of the acoustic wave device.

[0066] In other embodiments, the support structure can also be simultaneously disposed on the non-wiring layer around the resonant structure to enhance the support strength for the encapsulation layer and ensure better encapsulation quality of the formed acoustic wave device.

[0067] In some embodiments, the device area may include multiple resonant structures. At this time, the support structure can be formed only on the outermost wiring layer surrounding the device area. Or, the support structure can be formed on the wiring layer between adjacent resonant structures to improve the support for the encapsulation layer and improve the encapsulation airtightness of the acoustic wave device.

[0068] It should be noted that the support structure provided only on the wiring layer is non-closed, while the support structure provided on both the wiring layer and the non-wiring layer can be closed or non-closed.

[0069] In some embodiments, the resonant structure may include a thin film bulk acoustic resonator. Before forming the support structure, the method further includes:

[0070] As Figure 2a shown, a first sacrificial layer, a first electrode layer covering the first sacrificial layer, a piezoelectric layer covering the first electrode layer, a second electrode layer covering the piezoelectric layer, and an adjustment layer covering the second electrode layer are sequentially formed in the device region;

[0071] After forming the support structure as Figure 2b shown and before forming the encapsulation layer as Figure 2d shown, the method further includes:

[0072] As Figure 2c shown, the first sacrificial layer is removed, and a first cavity is formed between the first electrode layer and the substrate surface based on the topography of the first sacrificial layer to form the reflection structure of the resonant structure; the adjustment layer is trimmed.

[0073] The resonance region of the resonant structure includes: the first electrode layer, the piezoelectric layer, the second electrode layer, and the adjustment layer located on the first cavity.

[0074] The composition material of the first sacrificial layer may include: phosphosilicate glass (PSG) or silicon dioxide, etc. Taking the composition material of the first sacrificial layer as a silicon dioxide layer as an example, silane (SiH4) and oxygen (O2) can be used as reaction gases to form the first sacrificial layer on the substrate surface through chemical vapor deposition.

[0075] Exemplarily, the first sacrificial layer can be removed by wet etching. By selecting a suitable etchant and injecting the etchant into the first through hole exposing the first sacrificial layer, the etchant contacts the exposed first sacrificial layer and undergoes a chemical reaction to generate liquid or gaseous products.

[0076] Specifically, when the composition material of the first sacrificial layer is silicon dioxide, a wet etching process can be adopted, and hydrogen fluoride (HF) is selected as the etchant to remove the sacrificial layer. After hydrogen fluoride reacts with the sacrificial layer exposed through the first through hole, gaseous silicon tetrafluoride (SiF4) and liquid water are generated.

[0077] In some embodiments, after forming the support structure and before forming the encapsulation layer, a first through hole penetrating the adjustment layer, the second electrode layer, the piezoelectric layer, and the first electrode layer can be formed to expose the first sacrificial layer.

[0078] In some embodiments, before forming the support structure, a first via hole penetrating through the adjustment layer, the second electrode layer, the piezoelectric layer, and the first electrode layer may be formed to expose the first sacrificial layer.

[0079] In some embodiments, when forming the second electrode layer and the adjustment layer, the second electrode layer and the adjustment layer may expose the position of the piezoelectric layer corresponding to the first via hole. Thus, the first via hole only needs to penetrate through the piezoelectric layer and the first electrode layer.

[0080] When forming the support structure, a force is generated on the substrate surface, and this force may affect the resonant structure with the first cavity formed, increasing the probability of collapse of the first electrode layer, the piezoelectric layer, the second electrode layer, and the adjustment layer located above the first cavity, that is, increasing the probability of damage to the resonant structure including the first cavity and reducing the yield of the formed acoustic wave device.

[0081] Since the first cavity reduces the mechanical strength of the resonant structure, therefore, compared with forming the first cavity by first removing the first sacrificial layer and then forming the support structure, in the embodiments of the present disclosure, the support structure is formed first, and then the first sacrificial layer is removed to form the first cavity based on the morphology of the first sacrificial layer, so that the first electrode layer, the piezoelectric layer, the second electrode layer, and the adjustment layer located above the first cavity do not need to bear the force generated during the formation of the support structure, which is beneficial to ensuring the quality of the resonant structure with the first cavity formed, and further ensuring a high yield of the acoustic wave device.

[0082] It can be understood that the process of trimming the adjustment layer is a frequency modulation process for the resonant structure. Specifically, the adjustment layer can be bombarded with a laser or the like to thin the adjustment layer to achieve frequency modulation of the resonant structure. Wherein, the thickness of the trimmed adjustment layer is greater than or equal to 0.5 nm.

[0083] In some embodiments, the connection layer and the first electrode layer may be an integral structure formed simultaneously. In other embodiments, the connection layer and the second electrode layer may be an integral structure formed simultaneously.

[0084] In some embodiments, before forming the support structure, the method further includes:

[0085] In the device area, etching the substrate surface to form a groove on the substrate surface; forming a second sacrificial layer filling the groove; sequentially forming a first electrode layer covering the second sacrificial layer, a piezoelectric layer covering the first electrode layer, a second electrode layer covering the piezoelectric layer, and an adjustment layer covering the second electrode layer;

[0086] After forming the support structure and before forming the encapsulation layer, the method further includes:

[0087] Remove the second sacrificial layer, form a second cavity between the first electrode layer and the substrate surface based on the topography of the second sacrificial layer to form a reflective structure of the resonant structure; trim the adjustment layer.

[0088] Exemplarily, the device area on the substrate surface can be etched by a dry etching method to form the above-mentioned groove.

[0089] The composition material of the second sacrificial layer can be the same as that of the first sacrificial layer. For example, the composition material of the second sacrificial layer can include: phosphosilicate glass or silicon dioxide, etc. The formation process of the second sacrificial layer can also be the same as that of the first sacrificial layer. Details are not described here again.

[0090] Exemplarily, the second sacrificial layer can be removed by a wet etching process. For example, an etchant can be injected through the second through hole exposing the second sacrificial layer, so that the etchant contacts the exposed second sacrificial layer and undergoes a chemical reaction to generate a liquid product or a gaseous product to remove the second sacrificial layer.

[0091] In some embodiments, after forming the support structure and before forming the encapsulation layer, a second through hole penetrating the adjustment layer, the second electrode layer, the piezoelectric layer and the first electrode layer can be formed to expose the second sacrificial layer.

[0092] In some embodiments, before forming the support structure, a second through hole penetrating the adjustment layer, the second electrode layer, the piezoelectric layer and the first electrode layer can be formed to expose the second sacrificial layer.

[0093] In some embodiments, when forming the first electrode layer, the second electrode layer and the adjustment layer, the first electrode layer, the second electrode layer and the adjustment layer can expose the position of the piezoelectric layer corresponding to the second through hole. In this way, the second through hole only needs to penetrate the edge area of the piezoelectric layer to expose the second sacrificial layer.

[0094] When forming the support structure, a force will be generated on the substrate surface, and this force may affect the resonant structure with the second cavity formed, increasing the probability of collapse of the first electrode layer, the piezoelectric layer, the second electrode layer and the adjustment layer located above the second cavity, that is, increasing the probability of damage to the resonant structure including the second cavity and reducing the yield of the formed acoustic wave device.

[0095] Since the second cavity will reduce the mechanical strength of the resonant structure, compared with the method of forming an acoustic wave device by first forming a resonant structure with a second cavity on the substrate surface and then forming a support structure, in the embodiments of the present disclosure, the support structure is first formed, and then the second sacrificial layer is removed to form the second cavity based on the morphology of the second sacrificial layer, so that the first electrode layer, the piezoelectric layer, the second electrode layer, and the adjustment layer located above the second cavity do not need to bear the acting force generated during the formation of the support structure, which is beneficial to ensuring the quality of the resonant structure with the second cavity, and thus ensuring a high yield of the acoustic wave device.

[0096] In some embodiments, before forming the support structure, the method further includes:

[0097] Forming a reflection structure of the resonant structure, a first electrode layer covering the reflection structure, a piezoelectric layer covering the first electrode layer, a second electrode layer covering the piezoelectric layer, and an adjustment layer covering the second electrode layer in sequence in the device area on the substrate surface; trimming the adjustment layer.

[0098] Exemplarily, the resonant structure may further include a solidly mounted resonator. The forming a reflection structure of the resonant structure, a first electrode layer covering the reflection structure, a piezoelectric layer covering the first electrode layer, a second electrode layer covering the piezoelectric layer, and an adjustment layer covering the second electrode layer in sequence on the substrate surface includes:

[0099] Forming a first dielectric layer and a second dielectric layer that are alternately stacked on the substrate surface to form a reflection structure; wherein, the acoustic impedance of the first dielectric layer is different from that of the second dielectric layer;

[0100] Forming a first electrode layer covering the alternately stacked first dielectric layer and second dielectric layer;

[0101] Forming a piezoelectric layer covering the first electrode layer;

[0102] Forming a second electrode layer covering the piezoelectric layer;

[0103] Forming an adjustment layer covering the second electrode layer.

[0104] When the resonant structure includes a solidly mounted resonator, since there is no cavity in the reflection structure of the solidly mounted resonator, the acting force generated during the formation of the support structure will not damage the structure of the solidly mounted resonator. Therefore, the solidly mounted resonator can be formed first, and then the support structure can be formed.

[0105] When the resonant structure includes a thin film bulk acoustic resonator, the resonant structure can also be formed on the substrate surface first, and then the support structure can be formed.

[0106] It should be noted that when the support structure is first formed and then the first sacrificial layer or the second sacrificial layer is removed to form the reflective structure of the resonant structure, the etchant can be reasonably selected to ensure that the quality of the support structure is less affected or even not affected during the removal of the first sacrificial layer or the second sacrificial layer.

[0107] For example, when the support structure is first formed and then the first sacrificial layer is removed, an etchant with a high selectivity ratio for the first sacrificial layer and a low selectivity ratio for the support structure can be selected. Even an etchant that is inert to the chemical reaction with the support structure can be selected to reduce the chemical reaction between the etchant used to remove the first sacrificial layer and the support structure, ensure the structural integrity of the support structure, and further ensure good encapsulation airtightness for the acoustic wave device and improve the encapsulation quality.

[0108] The manufacturing method provided by the embodiments of the present disclosure can either complete the sacrificial layer removal process and the frequency modulation process of the acoustic wave device before forming the support structure, or complete the sacrificial layer removal process and the frequency modulation process of the acoustic wave device after forming the support structure. It integrates the front-end manufacturing process, the frequency modulation process, and the device encapsulation process of the acoustic wave device, provides a flexible manufacturing method for the acoustic wave device, is simple and low-cost, and has strong compatibility with the prior art.

[0109] Figure 3 is a schematic diagram of an acoustic wave device 100 shown according to an exemplary embodiment. The acoustic wave device 100 can be prepared according to the manufacturing method provided by the embodiments of the present disclosure. Refer to Figure 3 As shown, the acoustic wave device 100 includes:

[0110] A substrate 110;

[0111] A resonant structure 120, located on the surface of the substrate;

[0112] A connection layer 130 surrounding the resonant structure, located on the surface of the substrate;

[0113] A conductive support structure 140, located on the surface of the connection layer and surrounding the resonant structure; wherein, the height of the support structure is greater than the height of the resonant structure;

[0114] An encapsulation layer 150, located on the top of the support structure and covering the resonant structure;

[0115] Wherein, the resonant structure is located in the sealed cavity formed by the encapsulation layer, the support structure, the connection layer, and the substrate.

[0116] The constituent material of the substrate may include semiconductor materials, such as silicon or germanium, etc.

[0117] The resonant structure may include: a bulk acoustic wave resonant structure. For example, a thin film bulk acoustic wave resonant structure or a solid-state assembled resonant structure.

[0118] The wiring layer may be made of metal or alloy, such as aluminum, tungsten, copper, molybdenum or aluminum alloy. It is understood that the wiring layer is electrically connected to the resonant structure, and the wiring layer is used to transmit electrical signals.

[0119] The supporting structure may include metals or alloys, such as aluminum, tungsten, copper, molybdenum or aluminum alloys.

[0120] For example, in a direction perpendicular to the plane where the substrate is located, the height range of the support structure may include: 0.4 micrometers to 100 micrometers. Preferably, the height range of the support structure may include: 2 micrometers to 20 micrometers.

[0121] In some embodiments, the width of the support structure gradually increases from the substrate 110 toward the encapsulation layer 150. That is, the first contact area between the support structure and the encapsulation layer is greater than the second contact area between the support structure and the first electrode layer.

[0122] It is understandable that the larger the first contact area, the better the supporting effect of the support structure on the packaging layer, and it is beneficial to improve the airtightness of the packaging. It should be pointed out that when the first contact area increases, it is always necessary to ensure that there is a gap between the packaging layer and the resonance area of ​​the resonant structure, and there is a gap between the support structure and the resonance area.

[0123] When the second contact area increases, the support structure occupies a larger area of ​​the substrate, which may reduce the available area on the substrate. When the second contact area decreases, the support structure may be easily tilted. Therefore, the second contact area may be slightly smaller than the surface area of ​​the first electrode layer.

[0124] Compared with the first contact area between the support structure and the packaging layer being equal to or less than the second contact area between the support structure and the second electrode layer, in the embodiment of the present disclosure, the first contact area is greater than the second contact area. On the one hand, it can reduce the area occupied by the support structure on the substrate surface, while ensuring good airtightness of the package.

[0125] The disclosed embodiment forms a conductive support structure on the wiring layer on the surface of the substrate, and forms a packaging layer on top of the support structure to form the sealed cavity, thereby completing the packaging of the acoustic wave device. The process is simple and there is no need to use wafer bonding and TSV technology, which simplifies the packaging process for the acoustic wave device and reduces the packaging cost.

[0126] In addition, the present invention forms a conductive support structure on the wiring layer and adopts a connected structure formed by the wiring layer and the support structure as a path for transmitting electrical signals. Compared with only using the wiring layer as the path for transmitting electrical signals, the thickness of the path for transmitting electrical signals is increased and the resistance of the path is reduced, thereby reducing the electrical loss of the acoustic wave device, which is beneficial to improving the electrical performance of the acoustic wave device.

[0127] In some embodiments, the resonant structure includes:

[0128] A reflective structure, a first electrode layer, an adjustment layer, a second electrode layer, and an adjustment layer that are sequentially stacked; wherein, the reflective structure is located between the first electrode layer and the substrate surface.

[0129] The reflective structure is used to reflect acoustic signals. When the acoustic signals generated by the piezoelectric layer and / or the adjustment layer propagate towards the reflective structure, the acoustic signals can undergo total reflection at the interface where the first electrode layer contacts the reflective structure, causing the acoustic signals to be reflected back into the piezoelectric layer and / or the adjustment layer, confining the energy of the acoustic signals within the piezoelectric layer and / or the adjustment layer, thereby reducing the energy loss of the acoustic signals and improving the quality of the acoustic signals transmitted by the resonant structure.

[0130] The constituent materials of the first electrode layer and the second electrode layer may include: conductive materials composed of aluminum, molybdenum, ruthenium, iridium, platinum, etc. or their alloys.

[0131] The piezoelectric layer and the adjustment layer can be used to generate vibrations according to the inverse piezoelectric effect based on the electrical signals applied to the first electrode layer and the second electrode layer, converting the electrical signals into acoustic signals and achieving the conversion of electrical energy into mechanical energy.

[0132] The constituent materials of the piezoelectric layer and the adjustment layer may include: materials with piezoelectric properties. For example, aluminum nitride, zinc oxide, lithium tantalate, lead zirconate titanate, barium titanate, etc. The constituent materials of the piezoelectric layer and the adjustment layer may also include doped materials with piezoelectric properties, such as scandium-doped aluminum nitride, etc. The constituent materials of the piezoelectric layer and the adjustment layer may be the same. Among them, the thickness of the adjustment layer is greater than or equal to 0.5 nm.

[0133] The constituent materials of the adjustment layer may also include: silicon dioxide or electrode materials (for example, conductive materials composed of aluminum, molybdenum, ruthenium, iridium, platinum, etc. or their alloys).

[0134] In some embodiments, the reflective structure includes:

[0135] A first cavity, located between the first electrode layer and the substrate surface;

[0136] The first cavity is formed by removing a first sacrificial layer located between the substrate surface and the first electrode layer after forming the support structure and before forming the encapsulation layer.

[0137] Since the first cavity will reduce the mechanical strength of the resonant structure, therefore, compared with forming the first cavity by first removing the first sacrificial layer and then forming the support structure, the first cavity in the embodiments of the present disclosure is formed by removing the first sacrificial layer after the support structure is formed, so that the first electrode layer, the piezoelectric layer, the second electrode layer, and the adjustment layer located above the first cavity do not need to bear the acting force generated during the formation of the support structure, which is beneficial to ensuring the quality of the resonant structure with the first cavity, and further ensuring a high yield of the acoustic wave device.

[0138] In some embodiments, the first cavity is formed by removing the first sacrificial layer located between the substrate surface and the first electrode layer before forming the support structure.

[0139] In some embodiments, the reflective structure includes:

[0140] A second cavity formed by the substrate surface being recessed downward, located between the first electrode layer and the substrate surface;

[0141] The second cavity is formed by removing the second sacrificial layer filled in the groove recessed downward on the substrate surface after the support structure is formed and before the encapsulation layer is formed.

[0142] Since the second cavity will reduce the mechanical strength of the resonant structure, therefore, compared with forming the acoustic wave device by first forming the resonant structure with the second cavity on the substrate surface and then forming the support structure, the second cavity in the embodiments of the present disclosure is formed by removing the second sacrificial layer after the support structure is formed to form based on the morphology of the second sacrificial layer, so that the first electrode layer, the piezoelectric layer, the second electrode layer, and the adjustment layer located above the second cavity do not need to bear the acting force generated during the formation of the support structure, which is beneficial to ensuring the quality of the resonant structure with the second cavity, and further ensuring a high yield of the acoustic wave device.

[0143] In some embodiments, the second cavity is formed by removing the second sacrificial layer filled in the groove recessed downward on the substrate surface before forming the support structure.

[0144] In some embodiments, the reflective structure includes:

[0145] The first dielectric layer and the second dielectric layer are alternately stacked; wherein, the acoustic impedance of the first dielectric layer is different from that of the second dielectric layer.

[0146] The first dielectric layer and the second dielectric layer with different acoustic impedances are alternately stacked to form a Bragg reflector.

[0147] Exemplarily, the acoustic impedance of the first dielectric layer may be greater than that of the second dielectric layer. At this time, the composition material of the first dielectric layer may include: molybdenum or tungsten; the composition material of the second dielectric layer may include: silicon dioxide or aluminum.

[0148] Exemplarily, the acoustic impedance of the first dielectric layer may be less than that of the second dielectric layer. At this time, the constituent material of the first dielectric layer may include: silicon dioxide or aluminum; the constituent material of the second dielectric layer may include: molybdenum or tungsten.

[0149] In the embodiments provided in the present disclosure, it should be understood that the disclosed devices, systems and methods can be implemented in other ways. As mentioned above, the above are only specific embodiments of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present disclosure can easily think of changes or substitutions, which should be covered within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope of the claims.

Claims

1. A manufacturing method of an acoustic wave device, characterized in that, The acoustic wave device includes a resonant structure, and the method includes: forming a connection layer on the substrate surface around the device area of the substrate surface; wherein, the device area is used to arrange the resonant structure; forming a conductive support structure on the surface of the connection layer; wherein, the height of the support structure is greater than the height of the resonant structure; the forming of the conductive support structure on the surface of the connection layer includes: forming the conductive support structure on the surface of the connection layer by electroplating or vacuum coating; forming a packaging layer covering the device area on the top of the support structure; wherein, the packaging layer, the support structure, the connection layer and the substrate form a sealed cavity around the device area; after forming the support structure and before forming the packaging layer, forming a cavity reflection structure on the side of the resonant structure close to the substrate.

2. The method according to claim 1, wherein before forming the support structure, the method further includes: forming a first sacrificial layer, a first electrode layer covering the first sacrificial layer, a piezoelectric layer covering the first electrode layer, a second electrode layer covering the piezoelectric layer, and an adjustment layer covering the second electrode layer in sequence in the device area; after forming the support structure and before forming the packaging layer, the method further includes: removing the first sacrificial layer, forming a first cavity between the first electrode layer and the substrate surface based on the morphology of the first sacrificial layer to form a reflection structure of the resonant structure; trimming the adjustment layer.

3. The method according to claim 1, wherein before forming the support structure, the method further includes: etching the substrate surface in the device area to form a groove on the substrate surface; forming a second sacrificial layer filling the groove; sequentially forming a first electrode layer covering the second sacrificial layer, a piezoelectric layer covering the first electrode layer, a second electrode layer covering the piezoelectric layer, and an adjustment layer covering the second electrode layer; after forming the support structure and before forming the packaging layer, the method further includes: removing the second sacrificial layer, forming a second cavity between the first electrode layer and the substrate surface based on the morphology of the second sacrificial layer to form a reflection structure of the resonant structure; trimming the adjustment layer.

4. The method according to claim 1, characterized in that, before forming the support structure, the method further includes: forming a reflection structure of the resonant structure, a first electrode layer covering the reflection structure, a piezoelectric layer covering the first electrode layer, a second electrode layer covering the piezoelectric layer, and an adjustment layer covering the second electrode layer in sequence in the device area of the substrate surface; trimming the adjustment layer.

5. An acoustic wave device, characterized in that, including: a substrate; a resonant structure located on the substrate surface; a connection layer surrounding the resonant structure located on the substrate surface; a conductive support structure located on the surface of the connection layer and surrounding the resonant structure; wherein, the height of the support structure is greater than the height of the resonant structure; a packaging layer located on the top of the support structure and covering the resonant structure; Among them, the resonant structure is located in a sealed cavity formed by the encapsulation layer, the support structure, the connection layer, and the substrate; a cavity reflection structure is provided on the side of the resonant structure close to the substrate.

6. The acoustic wave device according to claim 5, wherein The resonant structure includes: The reflection structure, the first electrode layer, the adjustment layer, the second electrode layer, and the adjustment layer are stacked in sequence; wherein, the reflection structure is located between the first electrode layer and the surface of the substrate.

7. The acoustic wave device according to claim 6, wherein, The reflection structure includes: A first cavity, located between the first electrode layer and the surface of the substrate; The first cavity is formed by removing a first sacrificial layer located between the surface of the substrate and the first electrode layer after forming the support structure and before forming the encapsulation layer. Or, The first cavity is formed by removing a first sacrificial layer located between the surface of the substrate and the first electrode layer before forming the support structure.

8. The acoustic wave device according to claim 6, wherein, The reflection structure includes: A second cavity formed by the surface of the substrate being recessed downward, located between the first electrode layer and the surface of the substrate; The second cavity is formed by removing a second sacrificial layer filled in a groove recessed downward on the surface of the substrate after forming the support structure and before forming the encapsulation layer. Or, The second cavity is formed by removing a second sacrificial layer filled in a groove recessed downward on the surface of the substrate before forming the support structure.

9. The acoustic wave device according to claim 6, wherein, The reflection structure includes: The first dielectric layer and the second dielectric layer are stacked alternately; wherein, the acoustic impedance of the first dielectric layer is different from that of the second dielectric layer.

10. The acoustic wave device according to claim 5, characterized in that, The constituent material of the support structure includes: metal or metal alloy.

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