A film bulk acoustic resonator and a method of manufacturing the same

Abstract

This application provides a thin-film bulk acoustic wave resonator and its fabrication method. The method includes: providing a release substrate; fabricating a piezoelectric thin film stack structure with at least one elastic connection structure on the release substrate; providing a substrate with a cavity; placing the piezoelectric thin film stack structure in the cavity of the substrate and fixing at least one elastic connection structure of the piezoelectric thin film stack to the substrate; and peeling off the release substrate to form a thin-film bulk acoustic wave resonator. This application solves the problem of breakage at the bonding connection between the piezoelectric thin film stack structure and the substrate in related technologies, and improves the structural stability of the resonator.

Description

Technical Field

[0001] This application relates to the field of communication filtering technology, and in particular to a resonant filtering technology, specifically a thin-film bulk acoustic resonator and its fabrication method. Background Technology

[0002] With the development of wireless communication applications, people have increasingly higher requirements for data transmission speed. In the field of mobile communication, the first generation of communication technology is analog technology, the second generation of communication technology realizes digital voice communication, the third generation of communication technology is characterized by multimedia communication, the fourth generation of communication technology increases the communication rate to 1Gbps and reduces the latency to 10ms, and the fifth generation of communication technology is the next generation of mobile communication technology after the fourth generation. The fifth generation of communication technology aims to solve the communication between people and things, and between things, in addition to the communication between people, realizing the vision of "Internet of Everything".

[0003] The increase in data rates corresponds to higher spectrum utilization and more complex communication protocols. Due to limited spectrum, it is essential to fully utilize the spectrum to meet data rate demands. Furthermore, starting with fourth-generation (4G) communication technology, carrier aggregation technology has been used to allow a single device to transmit data simultaneously using different carrier spectrums. On the other hand, to support sufficient data transmission rates within limited bandwidth, communication protocols have become increasingly complex, thus placing stringent demands on the performance of various aspects of the radio frequency (RF) system. The most mainstream implementation methods for RF filters are surface acoustic wave (SAW) filters and filters based on thin-film bulk acoustic resonator (TFT) technology. SAW filters are more suitable for use below 1.5 GHz due to their inherent limitations. However, current wireless communication protocols have long been using frequency bands above 2.5 GHz, necessitating the use of TFT-based filters. The main component in a thin-film bulk acoustic wave (TFT) resonator is the TFT resonator itself. One type of TFT resonator includes a substrate with a groove structure and a stacked structure of piezoelectric thin films with an upper electrode, a piezoelectric thin film, and a lower electrode. The upper and lower electrodes are bonded to a bonding layer on the substrate, so that the stacked structure of piezoelectric thin films is disposed above the groove structure, thereby forming a cavity structure on the substrate.

[0004] In related technologies, piezoelectric thin film stacked structures are anchored to the substrate. This anchoring is achieved by widening and thickening the electrodes. However, the inventors discovered through research that there is anchor loss at the anchoring point. On the one hand, sound waves can leak through this anchoring point; on the other hand, the structure relies solely on the support force at the bonding joint to overcome its own weight, thus suspending itself above the cavity. When the aforementioned thin-film bulk acoustic resonator converts sound waves into electrical signals, the piezoelectric thin film stacked structure vibrates up and down, increasing the stress at the bonding joint and potentially causing it to break, thus affecting the stability of the resonator.

[0005] It should be noted that the description of the background technology in this application does not constitute prior art as defined in this application, nor does it limit the scope of application. For example, this application can be applied not only to the field of mobile communications, but also to other fields requiring radio frequency, such as Wi-Fi. Summary of the Invention

[0006] In view of the shortcomings of the related technologies, the thin film bulk acoustic resonator and its fabrication method provided in this application solve the problem of breakage at the bonding connection between the piezoelectric thin film stack structure and the substrate in the related technologies, and improve the structural stability of the resonator.

[0007] In a first aspect, this application provides a method for fabricating a thin-film bulk acoustic resonator, the method comprising: providing a release substrate; fabricating a piezoelectric thin film stack structure with at least one elastic connection structure on the release substrate; providing a substrate with a cavity; placing the piezoelectric thin film stack structure in the cavity of the substrate, and fixing at least one elastic connection structure of the piezoelectric thin film stack to the substrate; and peeling off the release substrate to form a thin-film bulk acoustic resonator.

[0008] Optionally, a release substrate is provided, on which a piezoelectric thin film stack structure with at least one elastic connection structure is prepared, comprising: providing the release substrate, coating a photolithographic layer on the release substrate; etching the photolithographic layer to form a plurality of photolithographic bumps in a predetermined area on the release substrate; and sequentially depositing a first electrode layer, a piezoelectric layer, and a second electrode layer on the release substrate with the plurality of photolithographic bumps to form at least one elastic connection structure on the plurality of photolithographic bumps, thereby obtaining the piezoelectric thin film stack structure with at least one elastic connection structure.

[0009] Optionally, after peeling off the substrate, the method further includes: etching a plurality of photolithographic bumps in the piezoelectric thin film stack structure to obtain the thin film bulk acoustic resonator.

[0010] Optionally, a substrate with a cavity is provided, comprising: providing a silicon dioxide layer having a first surface and a second surface disposed opposite to each other; depositing a first insulating layer on the first surface of the silicon dioxide layer and depositing a second insulating layer on the second surface of the silicon dioxide layer; etching the second insulating layer to a predetermined size to form a cavity in the second insulating layer; and depositing a metal layer on the surface of the second insulating layer with the cavity to obtain the substrate with the cavity.

[0011] Optionally, a release substrate is provided, on which a piezoelectric thin film stack structure with at least one elastic connection structure is formed, comprising: providing the release substrate, depositing a buffer layer on the release substrate, and forming the piezoelectric thin film stack structure with at least one elastic connection structure on the buffer layer.

[0012] Optionally, the plurality of photolithographic protrusions may be hemispherical, triangular, cylindrical, or cuboid in shape.

[0013] Optionally, the at least one elastic connection structure is integrally formed with the first electrode layer, and / or the at least one elastic connection structure is integrally formed with the second electrode.

[0014] Secondly, this application provides a thin-film bulk acoustic resonator, the resonator comprising: a substrate with a cavity and a piezoelectric thin film stack structure with at least one elastic connection structure; the piezoelectric thin film stack structure is disposed on the cavity of the substrate, and the at least one elastic connection structure of the piezoelectric thin film stack is fixedly connected to the substrate.

[0015] Optionally, the piezoelectric thin film stack structure includes: a first electrode layer, a piezoelectric layer, a second electrode layer, and at least one elastic connection structure; the piezoelectric layer is located between the first electrode layer and the second electrode layer, and the first electrode layer and the second electrode layer are disposed opposite to each other; the at least one elastic connection structure is used to fix the piezoelectric thin film stack structure to the substrate.

[0016] Optionally, the at least one elastic connection structure is integrally formed with the first electrode layer, and / or the at least one elastic connection structure is integrally formed with the second electrode.

[0017] Optionally, the shape of the at least one elastic connection structure includes a polygonal shape, a square wave shape, a wavy shape, an Ω shape, or a spring shape.

[0018] Optionally, the substrate includes: a first insulating layer, a silicon dioxide layer, a second insulating layer, and a metal layer; a cavity is provided in the second insulating layer and the metal layer, such that the piezoelectric thin film stack structure is disposed on the cavity, and the first electrode layer and / or the second electrode layer are fixedly connected to the metal layer through the at least one elastic connection structure.

[0019] Optionally, the at least one elastic connection structure includes one or a combination of tungsten, molybdenum, platinum, ruthenium, iridium, titanium tungsten, and aluminum.

[0020] Compared with related technologies, this application has the following advantages:

[0021] This application uses an elastic connection structure to bond the piezoelectric thin film stack structure to the substrate. The elastic deformation of this elastic connection structure reduces energy loss and releases supporting stress at the bonding point, which to some extent prevents breakage at the connection point, improves the structural stability of the resonator, and can also suppress transverse clutter to some extent, avoid energy loss, and improve the filtering performance of the resonator. Attached Figure Description

[0022] Figure 1 The diagram shown is a schematic representation of a thin-film bulk acoustic resonator provided in an exemplary embodiment of this application.

[0023] Figure 2 The diagram shown is a flowchart illustrating a method for fabricating a thin-film bulk acoustic resonator according to an exemplary embodiment of this application.

[0024] Figure 3 The image shown is an exemplary embodiment of this application. Figure 2 A detailed flowchart of step S101 is shown below;

[0025] Figure 4 The diagram shown is a schematic diagram of the fabrication of a piezoelectric thin film stacking structure provided in an exemplary embodiment of this application;

[0026] Figure 5 The diagram shown is a schematic diagram of substrate fabrication provided in an exemplary embodiment of this application;

[0027] Figure 6 The diagram shown is a schematic diagram of the bonding between the substrate and the piezoelectric thin film stack structure provided in an exemplary embodiment of this application;

[0028] Figure 7 The diagram shown is a schematic diagram of the peeling off of the substrate provided in an exemplary embodiment of this application;

[0029] Figure 8 The image shown is a top view schematic diagram of a thin-film bulk acoustic resonator provided in an exemplary embodiment of this application.

[0030] Explanation of reference numerals in the attached figures: 100, substrate; 110, release substrate; 120, buffer layer; 130, photolithography layer; 140, photolithography bump; 150, first electrode layer; 160, second electrode layer; 170, piezoelectric layer; 180, elastic connection structure; 200, piezoelectric thin film stacked structure; 210, silicon dioxide layer; 220, first insulating layer; 230, second insulating layer; 240, cavity; 250, metal layer. Detailed Implementation

[0031] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0032] The terminology used in this application is for the purpose of describing specific embodiments only and is not intended to limit the application. In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0033] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or a fixed connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0034] In this application, unless otherwise expressly specified and limited, "above" or "below" a second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of a second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" a second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature. Exemplary embodiments of this application will now be described in detail with reference to the accompanying drawings. Unless otherwise specified, the features in the following embodiments and implementations can complement or combine with each other.

[0035] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0036] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, 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 some embodiments of this application, not all embodiments. Unless otherwise specified, the following embodiments and features in the implementation methods can be combined with each other. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0037] In a first aspect, this application provides a thin-film bulk acoustic resonator, specifically including the following embodiments:

[0038] Exemplary Implementation Example 1

[0039] Figure 1 The diagram shown is a schematic representation of a thin-film bulk acoustic resonator provided in an exemplary embodiment of this application. Figure 1 As shown, this application provides a thin-film bulk acoustic resonator, specifically comprising:

[0040] A substrate 100 with a cavity 240 and a piezoelectric thin film stacked structure 200;

[0041] The piezoelectric thin film stack structure 200 includes a first electrode layer 150, a piezoelectric layer 170, a second electrode layer 160, and at least one elastic connection structure 180. The piezoelectric layer 170 is located between the first electrode layer 150 and the second electrode layer 160, and the first electrode layer 150 and the second electrode layer 160 are disposed approximately opposite to each other.

[0042] The piezoelectric thin film stack structure 200 is disposed on the cavity 240 of the substrate 100, and the first electrode layer 150 and / or the second electrode layer 160 are fixedly connected to the substrate 100 through at least one elastic connection structure 180. Specifically, the first electrode layer 150 and / or the second electrode layer 160 are fixedly connected to the substrate 100, and this connection can be referred to as anchoring. The anchoring is achieved through a structure with elastic deformation capability, which is the elastic connection structure.

[0043] The first electrode layer 150 is made of one or a combination of tungsten, molybdenum, platinum, ruthenium, iridium, titanium tungsten, and aluminum. The substrate is made of one of monocrystalline silicon, polycrystalline silicon, glass, quartz, or sapphire.

[0044] It should be noted that, in the embodiments of this application, the number of the elastic connection structures includes one or more. The first electrode layer 150 and / or the second electrode layer 160 of the piezoelectric thin film stack structure 200 are fixedly connected to the substrate 100 through the elastic connection structure 180. Since the elastic connection structure 180 itself has a certain elastic deformation capability, it can absorb / release the support stress at the connection between the piezoelectric thin film stack structure 200 and the substrate 100. On the one hand, it reduces the anchor loss, and on the other hand, it effectively prevents the connection from breaking, thereby improving the structural stability of the resonator and thus improving the stability of the product.

[0045] In addition, the elastic connection structure provided in this application embodiment can store other energy during the propagation process as elastic potential energy, and can convert elastic potential energy into other forms of energy, which can maintain the suppression of transverse clutter, avoid energy loss to a large extent, and improve the filtering performance of the resonator.

[0046] In one embodiment of the application, a first insulating layer 220, a silicon dioxide layer 210, a second insulating layer 230, and a metal layer 250 are sequentially disposed from bottom to top on the substrate 100. A cavity 240 is formed in the second insulating layer 230 and the metal layer 250, allowing the piezoelectric thin film stack structure 200 to be disposed on the cavity 240. The first electrode layer 150 and / or the second electrode layer 160 are fixedly connected to the metal layer 250 via at least one elastic connection structure 180. In other embodiments, the substrate contains only monocrystalline silicon. This is not a limitation; any implementation that achieves the desired function is acceptable.

[0047] It should be noted that, in this exemplary embodiment, the at least one elastic connection structure is integrally formed with the first electrode layer, and / or the at least one elastic connection structure is integrally formed with the second electrode.

[0048] It should be noted that, in this exemplary embodiment, the shape of the at least one elastic connection structure includes a polygonal shape, a square wave shape, a wavy shape, an Ω shape, or a spring shape.

[0049] It should be noted that, in this exemplary embodiment, the material of the at least one elastic connection structure includes one or a combination of tungsten, molybdenum, platinum, ruthenium, iridium, titanium tungsten, and aluminum.

[0050] like Figure 8 As shown in this exemplary embodiment, the elastic connection structure 180 can be positioned in an aligned manner, which, from a mechanical point of view, provides a relatively stable connection. Optionally, the position of the elastic connection structure can be arbitrarily set; for example, it can be positioned at one corner or diagonally. Specifically, Figure 8 The elastic connection structure 180 in the diagram is only a top view; in reality, it includes, but is not limited to, elastic connection structures composed of hemispherical, triangular, cylindrical, or cuboid shapes. Figure 8 The figure only shows two flexible connection structures that are not set. One or more flexible connectors can be set at any position according to actual needs. The figure only shows a schematic diagram of the first electrode layer 150 and the flexible connection structure 180. The setting method of the second electrode layer 160 and the elastic connection structure 180 is the same or similar to that of this embodiment, and will not be described again here.

[0051] Secondly, this application provides a method for fabricating a thin-film bulk acoustic resonator, specifically including the following embodiments:

[0052] Exemplary Embodiment Two

[0053] Figure 2 The diagram shown is a schematic flowchart of a method for fabricating a thin-film bulk acoustic resonator according to an exemplary embodiment of this application. Figure 2 As shown, the fabrication method of the thin-film bulk acoustic resonator provided in this application specifically includes the following steps. It should be noted that, within the limits allowed by the process, the steps can be substituted, and the steps do not constitute a limitation of this method:

[0054] Step S101: Provide a release substrate 110, and prepare a piezoelectric thin film stack structure 200 with at least one elastic connection structure 180 on the release substrate 110.

[0055] Specifically, in this embodiment, such as Figure 3 As shown, a release substrate 110 is provided, and a piezoelectric thin film stack structure 200 with at least one elastic connection structure 180 is formed on the release substrate 110. Specifically, the process includes the following steps:

[0056] Step S201: Provide the release substrate 110 and coat the release substrate 110 with a photolithography layer 130;

[0057] Step S202: Etch the photolithography layer 130 to form a plurality of photolithography protrusions 140 in a predetermined area on the stripped substrate 110.

[0058] Step S203: A first electrode layer 150, a piezoelectric layer 170, and a second electrode layer 160 are sequentially deposited on a release substrate 110 with the plurality of photolithographic bumps 140, so that at least one elastic connection structure 180 is formed on the plurality of photolithographic bumps 140, thereby obtaining the piezoelectric thin film stack structure 200 with at least one elastic connection structure 180.

[0059] It should be noted that, as Figure 4 As shown in Figure a, a release substrate 110 is provided, and a buffer layer 120 is deposited on the release substrate 110. The buffer layer 120 is mainly used to facilitate the separation of the release substrate 110 from the piezoelectric thin film stack structure 200. The buffer layer 120 can be a material such as silicon dioxide, silicon nitride, silicon oxynitride, and phosphoric acid release.

[0060] A photolithography layer 130 is formed on the buffer layer 120 by spin coating photoresist. A protective film is then applied to a predetermined area of ​​the photolithography layer 130. The photolithography layer 130 covered with the protective film is etched to remove the photoresist outside the protected area, thereby forming several photolithographic bumps 140 on the buffer layer. Figure 4 As shown in b. The plurality of photolithographic protrusions 140 are further polished to give them shapes including, but not limited to, hemispherical, triangular, cylindrical, or cuboid. The photolithographic protrusions 140 primarily serve a supporting function, forming elastic connection structures 180 of different shapes.

[0061] Furthermore, a first electrode layer 150, a piezoelectric layer 170, and a second electrode layer 160 are deposited on the buffer layer with the plurality of photolithographic bumps 140, thereby forming an elastic connection structure 180 on the plurality of photolithographic bumps, such as... Figure 4 As can be seen from c, one or more elastic connection structures 180 can be formed on the buffer layer 120 according to actual needs; and in order to make the thin film bulk acoustic resonator more structurally stable, the elastic connection structure 180 is integrally formed with the first electrode layer 150 or the second electrode layer 160, thereby forming the piezoelectric thin film stacked structure with at least one elastic connection structure.

[0062] Step S102, providing a substrate 100 with a cavity 240;

[0063] Specifically, providing a substrate 100 with cavity 240 includes: providing a silicon dioxide layer 210, the silicon dioxide layer 210 having a first surface and a second surface disposed opposite to each other; depositing a first insulating layer 220 on the first surface of the silicon dioxide layer 210, and depositing a second insulating layer 230 on the second surface of the silicon dioxide layer 210; etching the second insulating layer 230 according to a preset size to form a cavity 240 in the second insulating layer 230; and depositing a metal layer 250 on the surface of the second insulating layer 230 with cavity 240 to obtain the substrate 100 with cavity 240.

[0064] It should be noted that, as Figure 5 As shown in 5a and 5b, a silicon dioxide layer 210 with a first surface and a second surface disposed opposite to each other is provided. A first insulating layer 220 is deposited on the first surface of the silicon dioxide layer 210 as a substrate, and a second insulating layer 230 is deposited on the second surface of the silicon dioxide layer 210 as a support layer. The second insulating layer 230 is etched using a dry or wet method to form a cavity 240 of a predetermined size in the second insulating layer. The predetermined size matches the size of the piezoelectric thin film stack structure, such that the lateral width of the cavity 240 is greater than the lateral width of the piezoelectric thin film stack structure, and the deposition thickness of the second insulating layer 230 is greater than the longitudinal height of the piezoelectric thin film stack structure, thereby making the longitudinal height of the cavity 240 greater than the longitudinal height of the piezoelectric thin film stack structure.

[0065] Finally, a metal layer 250 is deposited on the surface of the second insulating layer with the cavity 240 to obtain the substrate with the cavity, as shown below. Figure 5 As shown in c.

[0066] Step S103: Place the piezoelectric thin film stack structure 200 in the cavity 240 of the substrate 100, and fix at least one elastic connection structure 180 of the piezoelectric thin film stack 200 to the substrate 100.

[0067] In this embodiment, when the piezoelectric thin film stack structure 200 is suspended in the cavity of the substrate 100, and when there are two elastic connection structures 180, and they are integrally formed with the first electrode layer 150 and the second electrode layer 160, the first end of the elastic connection structure 180 is integrally formed with the first electrode layer 150, and the second end of the elastic connection structure 180 is bonded to the metal layer 250 on the substrate, thereby elastically fixing the first electrode layer 150 in the piezoelectric template stack structure to the substrate through the elastic connection structure 180. Similarly, the first end of the elastic connection structure 180 is integrally formed with the second electrode layer 160, and the second end of the elastic connection structure 180 is bonded to the metal layer 250 on the substrate, thereby elastically fixing the second electrode layer 160 in the piezoelectric template stack structure to the substrate through the elastic connection structure 180.

[0068] Step S104: Peel off the peeled substrate 110 to form a thin-film bulk acoustic resonator.

[0069] In the embodiments of this application, such as Figure 6 As shown, the buffer layer 120 on the release substrate 110 is removed by wet process. The release substrate 110 and the buffer layer 120 are then separated from the first electrode layer 150 and the second electrode layer 160. Then, several photolithographic bumps 140 in the piezoelectric thin film stack structure are etched to obtain the following... Figure 1 The thin-film bulk acoustic resonator shown.

[0070] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

Claims

1. A method for fabricating a thin-film bulk acoustic resonator, characterized in that, The method includes: A release substrate is provided, on which a piezoelectric thin film stack structure with at least one elastic connection structure is prepared; Provide a substrate with a cavity; The piezoelectric thin film stack structure is placed in the cavity of the substrate, and at least one elastic connection structure of the piezoelectric thin film stack is fixedly connected to the substrate; The stripped substrate is peeled off to form a thin-film bulk acoustic resonator; The process of fabricating a piezoelectric thin film stack structure with at least one elastic connection structure on the release substrate includes: The release substrate is provided, and a photolithographic layer is coated on the release substrate; The photolithography layer is etched to form a plurality of photolithographic protrusions in a predetermined area on the stripped substrate. A first electrode layer, a piezoelectric layer, and a second electrode layer are sequentially deposited on a release substrate with the plurality of photolithographic bumps to form at least one elastic connection structure on the plurality of photolithographic bumps, thereby obtaining the piezoelectric thin film stack structure with at least one elastic connection structure. The bulk acoustic resonator of the thin film is obtained by etching several photolithographic protrusions in the piezoelectric thin film stack structure.

2. The method for fabricating a thin-film bulk acoustic resonator as described in claim 1, characterized in that, A cavity-containing substrate is provided, comprising: A silicon dioxide layer is provided, the silicon dioxide layer having a first surface and a second surface disposed opposite to each other; A first insulating layer is deposited on the first side of the silicon dioxide layer, and a second insulating layer is deposited on the second side of the silicon dioxide layer; The second insulating layer is etched according to a preset size to form a cavity in the second insulating layer; A metal layer is deposited on the surface of the second insulating layer with the cavity to obtain the substrate with the cavity.

3. The method for fabricating a thin-film bulk acoustic resonator as described in any one of claims 1-2, characterized in that, A release substrate is provided, on which a piezoelectric thin film stack structure with at least one elastic connection structure is formed, comprising: The release substrate is provided, and a buffer layer is deposited on the release substrate; The piezoelectric thin film stack structure with at least one elastic connection structure is prepared on the buffer layer.

4. The method for fabricating a thin-film bulk acoustic resonator as described in claim 1, characterized in that, The plurality of photolithographic bumps include hemispherical, triangular, cylindrical, or cuboid shapes.

5. The method for fabricating a thin-film bulk acoustic resonator as described in claim 1, characterized in that, The at least one elastic connection structure is integrally formed with the first electrode layer, and / or the at least one elastic connection structure is integrally formed with the second electrode.

6. A thin-film bulk acoustic resonator, characterized in that, The resonator is fabricated using a method for fabricating a thin-film bulk acoustic resonator as described in any one of claims 1-5, and the resonator comprises: A substrate with a cavity and a piezoelectric thin film stack structure with at least one elastic connection structure; The piezoelectric thin film stack structure is disposed on the cavity of the substrate, and at least one elastic connection structure of the piezoelectric thin film stack is fixedly connected to the substrate.

7. The thin-film bulk acoustic resonator as described in claim 6, characterized in that, The piezoelectric thin film stack structure includes: A first electrode layer, a piezoelectric layer, a second electrode layer, and at least one elastic connection structure; The piezoelectric layer is located between the first electrode layer and the second electrode layer, and the first electrode layer and the second electrode layer are disposed opposite to each other; The at least one elastic connection structure is used to fix the piezoelectric thin film stack structure to the substrate.

8. The thin-film bulk acoustic resonator as described in claim 7, characterized in that, The at least one elastic connection structure is integrally formed with the first electrode layer, and / or the at least one elastic connection structure is integrally formed with the second electrode.

9. The thin-film bulk acoustic resonator as described in claim 7, characterized in that, The shape of the at least one elastic connection structure includes a polygonal shape, a square wave shape, a wavy shape, an Ω shape, or a spring shape.

10. The thin-film bulk acoustic resonator as described in claim 7, characterized in that, The substrate includes: The structure consists of a first insulating layer, a silicon dioxide layer, a second insulating layer, and a metal layer. A cavity is provided in the second insulating layer and the metal layer, and the piezoelectric thin film stack structure is disposed in the cavity. The first electrode layer and / or the second electrode layer are fixedly connected to the metal layer through the at least one elastic connection structure.

11. The thin-film bulk acoustic resonator according to any one of claims 6-10, characterized in that, The at least one elastic connection structure includes one or a combination of tungsten, molybdenum, platinum, ruthenium, iridium, titanium tungsten, and aluminum.

Images