sonic device

Abstract

To provide an acoustic wave device having low transmission loss, excellent electromagnetic interference resistance, compact size, and good applicability in a wide band range. [Solution] An acoustic wave device (100) includes a first electrode (110), a piezoelectric layer (115), and a second electrode (120). The first electrode includes an edge. The piezoelectric layer is disposed on the first electrode and includes a flat region (115A) and a stepped region (115B). The stepped region corresponds to the edge of the first electrode. A second electrode is disposed on the flat region of the piezoelectric layer. The protrusions of the first electrode, the piezoelectric layer, and the second electrode onto a first plane (P1) at least partially overlap each other. The first plane is perpendicular to the stacking direction of the first electrode, the piezoelectric layer, and the second electrode. The shortest distance (Dt) between the protrusion of the stepped region onto the first plane and the protrusion of the second electrode onto the same plane is equal to or greater than a predetermined length.

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to acoustic wave devices, and more particularly to acoustic wave devices having an improved quality factor. [Background technology]

[0002] Modern radio frequency communication systems impose increasingly stringent performance requirements on high frequency components, driving acoustic resonator technology in important directions. Acoustic resonators can be utilized to achieve energy conversion between electrical energy and mechanical vibration energy based on the piezoelectric effect, and are therefore widely applied in applications such as radio frequency filtering. Acoustic resonators can include, for example, surface acoustic wave (SAW) devices and bulk acoustic wave (BAW) devices, the latter of which can include, for example, film bulk acoustic resonators (FBARs). Bulk acoustic wave devices can operate based on various wave modes within piezoelectric materials. Summary of the Invention

[0003] One embodiment provides an acoustic wave device including a first electrode, a piezoelectric layer, and a second electrode. The first electrode includes an edge. The piezoelectric layer is disposed on the first electrode and includes a flat region and a stepped region. The stepped region corresponds to the edge of the first electrode. The second electrode is disposed on the flat region of the piezoelectric layer. When protruding onto a first plane, the protrusions of the first electrode, the piezoelectric layer, and the second electrode at least partially overlap one another. The first plane is perpendicular to the stacking direction of the first electrode, the piezoelectric layer, and the second electrode. When protruding onto the first plane, the shortest distance between the protrusion of the stepped region and the protrusion of the second electrode is equal to or greater than a predetermined length.

[0004] Another embodiment provides an acoustic wave device manufactured by a manufacturing method. The manufacturing method includes forming a first electrode including an edge and forming a piezoelectric layer on the first electrode. The piezoelectric layer includes a flat region and a stepped region. The stepped region corresponds to the edge of the first electrode. The manufacturing method further includes forming a second electrode on the flat region of the piezoelectric layer. When protruding onto a first plane, the protruding portion of the first electrode, the protruding portion of the piezoelectric layer, and the protruding portion of the second electrode at least partially overlap one another. The first plane is perpendicular to the stacking direction of the first electrode, the piezoelectric layer, and the second electrode. When protruding onto the first plane, the shortest distance between the protruding portion of the stepped region and the protruding portion of the second electrode is equal to or greater than a predetermined length. [Brief explanation of the drawings]

[0005] [Figure 1] 1 illustrates a cross-sectional view of an acoustic wave device according to one embodiment.

[0006] [Figure 2] 2 shows an exemplary flow chart of a method for manufacturing the acoustic wave device of FIG.

[0007] [Figure 3] 2 illustrates an exemplary plan view of the acoustic wave device of FIG. 1.

[0008] [Figure 4] 1 shows a cross-sectional view of an acoustic wave device according to another embodiment.

[0009] [Figure 5] 1 shows a cross-sectional view of an acoustic wave device according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] In the following, exemplary embodiments will be described in detail with reference to the accompanying drawings, so that those skilled in the art can easily recognize them. The concept of the present invention is not limited to the exemplary embodiments described herein, and may be embodied in various forms. Descriptions of well-known parts may be omitted for clarity, and similar reference numerals may refer to similar elements throughout.

[0011] This document provides at least one detail that will help understand the present disclosure. However, those skilled in the art will understand that implementation of the present disclosure is not limited to these details. In some cases, to avoid obscuring the present disclosure, this document may not describe in detail some known structures, such as components, steps, programs, circuits, materials, etc. Some embodiments may include equivalents of the listed structures, additional structures (e.g., additional components or steps), or omit some structures. Without departing from the spirit of the present disclosure and without contradiction, structures in different embodiments may be substituted, recombined, mixed, and modified to achieve another embodiment that remains within the scope of the present disclosure. A structure described in one drawing or one embodiment may not be limited to that drawing or embodiment. Those skilled in the art should understand that the same components / steps may be referred to by different names or symbols in the industry. This document does not intend to distinguish between components / steps with different names that have the same function. When an element is said to be selectively or optionally arranged, it means that the element may be arranged or removed as needed, all of which are within the scope of the present disclosure.

[0012] In this document, terms such as "include," "contain," "have," and "possess" are open-ended terms that should be interpreted to mean "including, but not limited to." Thus, when these terms are used, they specify the presence of the corresponding feature but do not exclude the presence of other features. When "and / or" is used to connect multiple entities, it means at least one of those entities or any combination thereof. For example, "X, Y, and / or Z" may include all of the following cases: X only, Y only, Z only, a combination of X and Y, a combination of X and Z, a combination of Y and Z, and a combination of all three of X, Y, and Z. When an element is referred to as being coupled to another element, it may be directly coupled or indirectly coupled. Direct coupling may include, for example, direct electrical coupling, such as being coupled only through contacts, e.g., metal wires. Indirect coupling may include, for example, coupling through another element (such as an active or passive element), coupling through a signal, etc. Directional terms used herein, such as "above," "below," "front," "rear," "left," "right," "inner," "outer," etc., are used for general description of relative positions and are not intended to limit the scope of the present disclosure.

[0013] When an object is referred to as being disposed or formed on another object, this describes the spatial relationship of the relative placement in a location or manufacturing process, and the two objects may or may not be in direct contact. Because the areas occupied by two objects may differ, when object A is referred to as being disposed or formed on object B, this may be interpreted as at least a portion of object A being disposed or formed on at least a portion of object B, such that the projections of object A and object B may at least partially overlap along their stacking direction. When object A and object B are referred to as overlapping, this may mean that the projections of object A and object B at least partially overlap, and object A and object B may be in contact or not in contact. For simplicity, drawings may depict only a portion of the components / steps and may not necessarily be drawn to scale.

[0014] Generally, in the fabrication of acoustic wave resonators, thin film deposition techniques may be used to fabricate each layer structure. For example, a piezoelectric layer may be formed on an electrode. However, because the electrode has a certain thickness, when the piezoelectric layer is formed on the electrode, the crystal structure of the piezoelectric layer may become irregular at the edge of the electrode, which may affect the piezoelectric effect of the piezoelectric layer. This affects the quality factor (Q value) and the electromechanical coupling coefficient (kt 2 This problem can be particularly significant in high frequency applications. For example, the effects of irregular crystal structure are more pronounced in thinner piezoelectric layers.

[0015] FIG. 1 shows a cross-sectional view of an exemplary acoustic wave device 100. The acoustic wave device 100 may include a substrate 105, a first electrode 110, a piezoelectric layer 115, and a second electrode 120. As shown, the substrate 105 may include a cavity A1. The first electrode 110 may be formed on the substrate 105 and may cover the cavity A1. The piezoelectric layer 115 may cover the first electrode 110 and may further cover the substrate 105. The second electrode 120 may be formed on the piezoelectric layer 115. For example, the first electrode 110 may be a bottom electrode, the second electrode 120 may be a top electrode, and the piezoelectric layer 115 may be formed at least partially between the first electrode 110 and the second electrode 120.

[0016] In some embodiments, the material of the substrate 105 may include silicon, glass, ceramic, gallium arsenide, and silicon carbide. The cavity A1 of the substrate 105 may be filled with air. Alternatively, the cavity A1 may be filled with a polymer material, a porous material, or an inert gas, depending on the desired acoustic properties. The first electrode 110 and the second electrode 120 may be conductors including, for example, molybdenum (Mo), copper (Cu), aluminum (Al), gold (Au), platinum (Pt), tungsten (W), other suitable metals, and / or combinations thereof.

[0017] In some embodiments, the material of the piezoelectric layer 115 may include a piezoelectric single crystal material, a piezoelectric polycrystalline (e.g., piezoelectric ceramic) material, a piezoelectric polymer, and a piezoelectric composite material. For example, the material of the piezoelectric layer 115 may include zinc oxide (ZnO), aluminum nitride (AlN), lithium tantalate (e.g., LiTaO), lithium niobate (e.g., LiNbO), quartz (QZ), lead titanate (e.g., PTO), lead zirconate titanate (e.g., PZT), and / or combinations thereof. In some embodiments, the piezoelectric layer 115 may be further doped with scandium (Sc).

[0018] In this document, when chemical formulas are mentioned, their stoichiometric ratios are provided as examples. Reasonable adjustments to the stoichiometric ratios to accommodate different process conditions or performance requirements without affecting the fundamental properties of the material are all within the scope of the embodiments. For example, lithium niobate can be expressed as LiNbO3 or Li x NbO y (where x and y may be integer or non-integer parameters), and silicon nitride may be Si3N4 or SiN x and other variations such as, all of which are within the scope of the embodiments.

[0019] Furthermore, the substrate 105, the first electrode 110, the piezoelectric layer 115, and the second electrode 120 may be sequentially stacked along a first direction DR1 such that, when projecting onto a first plane P1, the protrusions of the cavity A1 of the substrate 105, the protrusions of the first electrode 110, the protrusions of the piezoelectric layer 115, and the protrusions of the second electrode 120 at least partially overlap one another. For example, the first plane P1 may be perpendicular to the first direction DR1. For example, when projecting onto the first plane P1 along the first direction DR1, the overlapping region of the cavity A1, the first electrode 110, the piezoelectric layer 115, and the second electrode 120 may correspond to a resonance region R1 of the acoustic wave device 100. In other words, the resonance region R1 of the acoustic wave device 100 may include the overlap region along the first direction DR1 of the cavity A1, the first electrode 110, the piezoelectric layer 115, and the second electrode 120. In some cases, the resonance region R1 of the acoustic wave device 100 may also be referred to as the active region, which is designed to function as the primary region of the piezoelectric effect and enable electro-acoustic coupling and resonance functionality.

[0020] In some embodiments, the acoustic wave device 100 may further include a protective layer 130. The protective layer 130 may be disposed on at least the second electrode 120 to protect the second electrode 120 and other material layers. As shown, a portion of the protective layer 130 may be disposed on the piezoelectric layer 115. A metal pad 140 may be disposed on the protective layer 130.

[0021] For example, the material of the protective layer 130 may be the following material: silicon oxide (SiO x ), silicon nitride (SiN x ), and silicon oxynitride (SiON). For example, the protective layer 130 may include silicon dioxide (e.g., SiO2) and / or silicon nitride (e.g., Si3N4). The protective layer 130 may provide electrical insulation protection, moisture resistance, corrosion resistance, contamination resistance, and debris resistance. The protective layer 130 may be further configured to fine-tune the operating frequency. In some embodiments, the protective layer 130 may function as a waveguiding layer that modulates the propagation velocity of acoustic waves to increase sensitivity to surface perturbations. In some implementations, the thickness H of the protective layer 130 may be between 270 nanometers (nm) and 330 nanometers.

[0022] In some embodiments, the acoustic wave device 100 may further include a metal pad 140 and a connecting portion 150. The metal pad 140 may be disposed on the protective layer 130. For example, the metal pad 140 may be electrically connected to the second electrode 120 through a conductive via 133 in the protective layer 130. Using the metal pad 140, a signal may be transmitted to the second electrode 120 or from the second electrode 120 to an external component. The connecting portion 150 may be electrically connected to the metal pad 140, for example, may be disposed on the metal pad 140, and may serve as a connecting component between the acoustic wave device 100 and other components. In other cases, the connecting portion 150 may serve as a support for the acoustic wave device 100.

[0023] In some embodiments, the acoustic wave device 100 may further include a metal pad 142 and a connecting portion 152, and the metal pad 142 may be disposed on the protective layer 130. For example, the metal pad 142 may be electrically connected to the first electrode 110 through a conductive via 136 in the protective layer 130. Using the metal pad 142, a signal may be transmitted to the first electrode 110 or from the first electrode 110 to an external component. The connecting portion 152 may be electrically connected to the metal pad 142, for example, may be disposed on the metal pad 142, and may serve as a connecting component between the acoustic wave device 100 and other components. In other cases, the connecting portion 152 may serve as a support for the acoustic wave device 100.

[0024] For example, the material of metal pads 140 and / or 142 may include aluminum or gold, although other suitable metal pads may be used depending on the packaging process and engineering requirements. The material of connection portions 150 and / or 152 may include aluminum (Al), copper (Cu), gold (Au), nickel (Ni), tin-silver-copper alloy (SAC), tin-silver alloy (SnAg), tin-lead alloy (SnPb), silver (Ag), and / or tin-based alloys.

[0025] Regarding the connection between the first electrode 110 and an external circuit, the following is described. The connection portion 150 may include a bonding pad, a solder ball, a conductive bump, and / or a conductive pillar, and an appropriate connection portion 150 may be selected based on the packaging process or engineering requirements. In some embodiments, the acoustic wave device 100 may be mounted on a packaging substrate through the connection portion 150 using a flip-chip bonding technique. This bonding technique has advantages such as a short electrical path, small parasitic effects, and excellent high-frequency characteristics. In addition, the connection portion 150 may be used with other packaging techniques, such as wire bonding, ball grid array (BGA) packaging, or wafer-level packaging (WLP), to enable electrical connection and mechanical fixation between the acoustic wave device 100 and the package body, thereby ensuring the performance of the acoustic wave device 100 under various packaging architectures.

[0026] In some embodiments, the acoustic wave device 100 may utilize the piezoelectric effect to perform electroacoustic transduction. When a radio frequency electrical signal is applied between the first electrode 110 and the second electrode 120, an electric field is generated in the piezoelectric layer 115, causing the piezoelectric material to vibrate along a certain direction (e.g., along the first direction DR1). When the thickness of the piezoelectric layer 115 is equal to an integer multiple of half the acoustic wavelength, a standing wave resonance may be formed. The resonant frequency may be determined, for example, by the thickness of the piezoelectric layer 115 and the acoustic velocity, and may be expressed as fr = n × v / (2 × t), where fr is the resonant frequency, v is the acoustic velocity, t is the thickness of the piezoelectric layer 115, and n is a predetermined integer. Signal filtering at specific frequencies may be achieved using the acoustic wave device 100.

[0027] In some embodiments, the resonant frequency band of the acoustic wave device 100 may be located between 100 MHz and 20 GHz. This frequency range covers several important communication frequency bands. By adjusting the thickness of the piezoelectric layer 115, the dimensions of the first electrode 110 and the second electrode 120, and the material composition, the resonant frequency band of the acoustic wave device 100 may be tuned to a target frequency band to meet the specification requirements of a desired communication protocol.

[0028] 1 , as described above, a portion of the piezoelectric layer 115 may be disposed on the first electrode 110, and another portion may be disposed on the substrate 105. As shown, the first electrode 110 may include a first edge E1. The piezoelectric layer 115 may include a flat region 115A and a stepped region 115B. The stepped region 115B corresponds to the first edge E1 of the first electrode 110. The second electrode 120 may be disposed on the flat region 115A of the piezoelectric layer 115.

[0029] In the above-described embodiment, when the piezoelectric layer 115 is formed on the first electrode 110 during the deposition process, the piezoelectric material at the first edge E1 of the first electrode 110 may not be flat due to the thickness of the first electrode 110, and thus a stepped structure, i.e., a stepped region 115B, may be formed near the first edge E1. Compared with the flat region 115A of the piezoelectric layer 115, the crystalline arrangement of the stepped region 115B may be irregular. In other words, the crystalline orientation in the stepped region 115B may be less uniform than that in the flat region 115A. As described above, the resonant region R1 of the acoustic wave device 100 may include an overlap region along the first direction DR1 of the cavity A1, the first electrode 110, the piezoelectric layer 115, and the second electrode 120.

[0030] In some embodiments, to avoid or mitigate adverse effects of the stepped region 115B of the piezoelectric layer 115, it is desirable for the resonance region R1 of the acoustic wave device 100 to be as far away from the stepped region 115B as possible within a reasonable range. Furthermore, it is desirable for the second electrode 120 formed on the piezoelectric layer 115 to be as far away from the stepped region 115B as possible within a reasonable range. For example, the horizontal distance Dt between the stepped region 115B and the second electrode 120 may be equal to or greater than a predetermined length. Furthermore, the distance Dt may be defined as the shortest distance between the protrusion of the stepped region 115B onto the first plane P1 and the protrusion of the second electrode 120 onto the same plane P1. Furthermore, the second electrode 120 may include a second edge E2. The shortest distance may refer to the shortest distance between the protrusion of the stepped region 115B onto the first plane P1 and the protrusion of the second edge E2. For example, the distance Dt may be greater than or equal to 6 micrometers, which may be expressed as Dt≧6 μm.

[0031] In comparison, if the resonance region R1 of the acoustic wave device is too close to or overlaps the stepped region 115B of the piezoelectric layer 115, the crystal orientation defects in the stepped region 115B may be detrimental to acoustic wave propagation by causing scattering losses, thereby degrading the quality factor and electromechanical coupling coefficient of the acoustic wave device 100, which may affect performance. The structure of the embodiment of the present disclosure may effectively avoid the above problem. In FIG. 1, the shortest distance Dt may be greater than or equal to a predetermined length, so that the resonance region R1 may be effectively prevented from being too close to the stepped region 115B of the piezoelectric layer 115.

[0032] 2 shows an exemplary flowchart of a method 200 for manufacturing an acoustic wave device according to one embodiment. As shown in FIGS. 1 and 2, the manufacturing method 200 may include the following steps.

[0033] Step 205: Provide a substrate 105.

[0034] Step 210: Form a first electrode 110 on the substrate 105.

[0035] Step 215: Form the piezoelectric layer 115 on the first electrode 110.

[0036] Step 220: Form the second electrode 120 on the piezoelectric layer 115.

[0037] Step 225: Form a protective layer 130 on the second electrode 120.

[0038] Step 230: Form a conductive via 133 in the protective layer 130, and form a metal pad 140 on the protective layer 130, where the metal pad 140 is electrically connected to the second electrode 120 through the conductive via 133.

[0039] Step 235: Forming the connection portion 150 electrically connected to the metal pad 140.

[0040] In some embodiments, the manufacturing method 200 may further include forming a conductive via 136 in the protective layer 130 and forming a metal pad 142 on the protective layer 130. The metal pad 142 is electrically connected to the first electrode 110 through the conductive via 136. Optionally, a connection portion 152 may be formed to be electrically connected to the metal pad 142.

[0041] Each layer structure of the acoustic wave device 100 has been described above and will not be repeated here. The steps may be performed sequentially, or the order of the steps may be adjusted according to the requirements of the semiconductor process, all of which are within the scope of the embodiments.

[0042] Figure 3 shows a top view of the acoustic wave device 100 of Figure 1. Figure 3 shows the substrate 105, the first electrode 110, the piezoelectric layer 115, and the second electrode 120. For clarity and illustration purposes, the protective layer 130, the cavity A1, the metal pads 140 and 142, the conductive vias 133 and 136, and the connecting portions 150 and 152 may be omitted from Figure 3.

[0043] While FIG. 3 illustrates the positions of various layers and components in a top view, their vertical stacking relationship may be as shown in FIG. 1. As shown in FIG. 3, the shortest distance Dt between the protrusion of the second edge E2 of the second electrode 120 and the protrusion of the stepped region 115B of the piezoelectric layer 115 may be equal to or greater than a predetermined length (e.g., without limitation, 6 micrometers). Therefore, degradation of the quality factor and electromechanical coupling coefficient due to the stepped region may be effectively avoided. In FIG. 3, the substrate 105, the first electrode 110, the piezoelectric layer 115, and the second electrode 120 are each shown in a rectangular configuration, but this is merely an example. In some embodiments, the shapes may be polygonal, circular, elliptical, or other suitable geometric configurations.

[0044] In some embodiments, multiple acoustic wave devices may share some components. Figure 4 shows a schematic diagram of acoustic wave device 100 and acoustic wave device 400 according to another embodiment. Similarities between Figure 4 and Figure 1 will not be repeated here. Figure 4 further illustrates acoustic wave device 400.

[0045] As shown in FIG. 4 , the substrate 105 may further include a cavity A4. The first electrode 110 of the acoustic wave device 100 may extend to cover the cavity A4. The piezoelectric layer 115 may further extend to cover the extended first electrode 110. The acoustic wave device 400 may further include a second electrode 420 formed on the piezoelectric layer 115. The protective layer 130 may extend to cover the second electrode 420. In the acoustic wave device 400, the protrusions of the cavity A4, the first electrode 110, the piezoelectric layer 115, and the second electrode 420 onto the first plane P1 at least partially overlap each other. The resonance region R4 of the acoustic wave device 400 may include an overlapping region of the cavity A4, the first electrode 110, the piezoelectric layer 115, and the second electrode 420 along the first direction DR1. The resonant region R4 may be the active region of the acoustic wave device 400. In the above implementation, the substrate 105, the first electrode 110, the piezoelectric layer 115, and the protective layer 130 are shared by the acoustic wave devices 100 and 400.

[0046] In some embodiments, the acoustic wave device 400 may further include a metal pad 440 and a connecting portion 450, and the metal pad 440 may be electrically connected to the second electrode 420 through a conductive via 433 in the protective layer 130. Using the metal pad 440, a signal may be transmitted to the second electrode 420 or from the second electrode 420 to an external circuit. As shown in FIG. 4 , the connecting portion 450 may be electrically connected to the metal pad 440, for example, formed on the metal pad 440. The materials, shapes, and uses of the metal pad 440 and the connecting portion 450 may be similar to those of the metal pad 140 and the connecting portion 150, respectively, and therefore will not be repeated here.

[0047] 1, in the acoustic wave device 400, the second electrode 420 may be disposed on the flat region 115A of the piezoelectric layer 115. The first electrode 110 may further include another edge E11. The piezoelectric layer 115 may have a stepped region 415B. The stepped region 415B corresponds to the edge E11 of the first electrode 110. The second electrode 420 may have a second edge E42. A minimum distance (denoted as D4) between the protrusion of the second edge E42 and the protrusion of the stepped region 415B onto the first plane P1 may be equal to or greater than a predetermined length (e.g., 6 micrometers), thereby avoiding or mitigating degradation of the quality factor and reduction of the electromechanical coupling coefficient caused by crystal orientation irregularities in the stepped region 415B of the piezoelectric layer 115.

[0048] Figure 5 shows a schematic diagram of acoustic wave device 100 and acoustic wave device 500 according to another embodiment. Similarities between Figure 5 and Figure 1 will not be repeated here. Figure 5 further shows acoustic wave device 500.

[0049] As shown in FIG. 5 , the substrate 105 may further have a cavity A5. The acoustic wave device 500 may further include a first electrode 112, which may be formed on the substrate 105 and cover the cavity A5. A piezoelectric layer 115 may cover the first electrode 112. Furthermore, the first electrode 112 of the acoustic wave element 500 may be electrically disconnected from the first electrode 110 of the acoustic wave device 100. The second electrode 120 of the acoustic wave device 100 may extend to function as a top electrode for the acoustic wave device 500. For the acoustic wave device 500, the protrusion of the cavity A5, the protrusion of the first electrode 112, the protrusion of the piezoelectric layer 115, and the protrusion of the second electrode 120 onto the first plane P1 at least partially overlap one another. The resonance region R5 of the acoustic wave device 500 may include an overlap region of the cavity A5, the first electrode 112, the piezoelectric layer 115, and the second electrode 120 along the first direction DR1. The resonance region R5 may be an active region of the acoustic wave device 500. In the above implementation, the substrate 105, the piezoelectric layer 115, the second electrode 120, and the protective layer 130 are shared by the acoustic wave devices 100 and 500.

[0050] In some embodiments, the acoustic wave device 500 may further include a metal pad 540 and a connecting portion 550. The metal pad 540 may be electrically connected to the first electrode 112 through a conductive via 533. For example, the conductive via 533 may pass through the protective layer 130 and may further pass through the piezoelectric layer 115.

[0051] In the acoustic wave device 500, the first electrode 112 may include an edge E12. The piezoelectric layer 115 may have a stepped region 515B, which corresponds to the edge E12 of the first electrode 112. The second electrode 120 may have an edge E52, and a minimum distance (denoted as D5) between the protrusion of the edge E52 and the protrusion of the stepped region 515B onto the first plane P1 may be equal to or greater than a predetermined length (for example, but not limited to, 6 micrometers), thereby avoiding or mitigating adverse effects caused by crystal orientation irregularities in the stepped region 515B of the piezoelectric layer 115.

[0052] 4 and 5 described above are used merely to illustrate the configuration of multiple acoustic wave devices and are not intended to limit the present disclosure. In further embodiments, the bottom electrode, the top electrode, or both may be selectively extended as needed to facilitate the formation of three or more acoustic wave devices.

[0053] In summary, the exemplary acoustic wave devices 100, 400, and 500 provided by the embodiments may position the top electrode away from the stepped region of the piezoelectric layer, thereby optimizing the shortest distance (e.g., 6 micrometers or more) between the resonant region of the piezoelectric layer and the stepped region to avoid or mitigate adverse effects caused by the irregular crystalline structure of the stepped region. Therefore, the quality factor and the electromechanical coupling coefficient may be effectively improved. The technical solutions of the embodiments are not only applicable to a single acoustic wave device, but also to the integration of multiple acoustic wave devices.

[0054] Furthermore, the acoustic wave device provided by the embodiments may be advantageous in low transmission loss, excellent electromagnetic interference resistance, and compact size, and may have good applicability in a wide band range of 100 MHz to 20 GHz, which may meet the requirements of various communication protocols, such as, but not limited to, mobile communication systems (such as GSM, CDMA, WCDMA, LTE, LTE-A, 5G, 6G), wireless network protocols (such as WiFi, Bluetooth, WiMAX), and other communication technologies (such as IoT, V2X, mmWave, etc.).

[0055] Those skilled in the art will readily appreciate that numerous modifications and variations of the devices and methods may be made while retaining the teachings of the present invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.

Claims

1. a first electrode including a first edge; a piezoelectric layer disposed on the first electrode, the piezoelectric layer including a flat region and a stepped region, the stepped region corresponding to the first edge of the first electrode; a second electrode disposed on the planar region of the piezoelectric layer; When projecting onto a first plane, the protrusions of the first electrode, the protrusions of the piezoelectric layer, and the protrusions of the second electrode at least partially overlap one another, and the first plane is perpendicular to a stacking direction of the first electrode, the piezoelectric layer, and the second electrode; When the stepped region protrudes onto the first plane, the shortest distance between the protruding portion of the stepped region and the protruding portion of the second electrode is equal to or greater than a predetermined length. Sonic device.

2. The acoustic wave device of claim 1 , wherein the predetermined length is substantially 6 micrometers.

3. The acoustic wave device of claim 1 , wherein the piezoelectric layer has less crystalline orientation uniformity in the stepped regions than in the flat regions.

4. The acoustic wave device of claim 1 , wherein the second electrode includes a second edge, and the shortest distance refers to the shortest distance between the protrusion of the stepped region and the protrusion of the second edge.

5. The acoustic wave device of claim 1 , further comprising a substrate, the first electrode being disposed on the substrate.

6. The acoustic wave device of claim 5 , wherein the material of the substrate comprises at least one of silicon, glass, ceramic, gallium arsenide, and silicon carbide.

7. the substrate includes a cavity; When projecting onto a first plane, the protrusion of the cavity, the protrusion of the first electrode, the protrusion of the piezoelectric layer, and the protrusion of the second electrode at least partially overlap one another. The acoustic wave device of claim 5 .

8. 8. The acoustic wave device of claim 7, wherein an overlap area of ​​the cavity, the first electrode, the piezoelectric layer, and the second electrode when projected above the first plane corresponds to a resonant area of ​​the acoustic wave device.

9. The acoustic wave device of claim 1 , further comprising a protective layer disposed on at least the second electrode.

10. 10. The acoustic wave device of claim 9, further comprising a metal pad disposed on the protective layer, the metal pad electrically connected to the second electrode through a via in the protective layer.

11. The acoustic wave device of claim 10 , wherein the material of the metal pads includes aluminum or gold.

12. The acoustic wave device of claim 10 , further comprising a connection portion electrically connected to the metal pad.

13. The acoustic wave device of claim 12 , wherein the connecting portion comprises a bonding pad, a solder ball, a conductive bump, and / or a conductive pillar.

14. The acoustic wave device of claim 1 , wherein the first electrode extends to function as an electrode for another acoustic wave device.

15. The acoustic wave device of claim 1 , wherein the second electrode extends to function as an electrode for another acoustic wave device.

16. The acoustic wave device of claim 1 , wherein the resonant frequency band of the acoustic wave device is in the range of 100 MHz to 20 GHz.

17. 10. The acoustic wave device of claim 1, wherein the material of the piezoelectric layer comprises at least one of zinc oxide, aluminum nitride, lithium tantalate, lithium niobate, quartz, lead titanate, lead zirconate titanate, and scandium.

18. The acoustic wave device of claim 1 , wherein the material of the first electrode or the material of the second electrode includes at least one of molybdenum, copper, aluminum, gold, platinum, and tungsten.

19. An acoustic wave device manufactured by a manufacturing method, comprising: The manufacturing method includes: forming a first electrode, the first electrode including a first edge; forming a piezoelectric layer disposed on the first electrode, the piezoelectric layer including a flat region and a stepped region, the stepped region corresponding to the first edge of the first electrode; forming a second electrode, the second electrode being disposed on the planar region of the piezoelectric layer; When projecting onto a first plane, the protrusions of the first electrode, the protrusions of the piezoelectric layer, and the protrusions of the second electrode at least partially overlap one another, and the first plane is perpendicular to a stacking direction of the first electrode, the piezoelectric layer, and the second electrode; When the stepped region protrudes onto the first plane, the shortest distance between the protruding portion of the stepped region and the protruding portion of the second electrode is equal to or greater than a predetermined length. Sonic device.

20. 20. The acoustic wave device of claim 19, wherein the predetermined length is substantially 6 micrometers.

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