Acoustic wave device

Abstract

An acoustic wave device includes a first electrode, a piezoelectric layer, and a second electrode. The piezoelectric layer is at least partially disposed on the first electrode. The second electrode is at least partially disposed on the piezoelectric layer. The second electrode includes an electrode body having an outer contour; and a plurality of protruding parts protruding from the outer contour of the electrode main body. A gap is formed between the two tail ends of every two adjacent protruding parts, and at least one part of the piezoelectric layer is exposed out of the gap.

Description

Technical Field

[0001] The present invention relates to acoustic wave technology, and more particularly to a bulk acoustic wave device. Background Art

[0002] Bulk acoustic wave (BAW) devices can be used to convert and transmit electrical and acoustic signals. BAW devices are widely used in communications, global positioning systems (GPS), and military fields. BAW devices can be used in filters, which can filter noise and retain wireless signals in the required frequency band, provide low transmission loss and anti-electromagnetic interference, and are compact, so they are widely used in various communication products. In addition, BAW filters can also be used as resonators. Current BAW devices may produce spurious modes, causing unnecessary energy leakage and reducing circuit performance. Summary of the invention

[0003] The present invention discloses an acoustic wave device, comprising a first electrode, a piezoelectric layer and a second electrode. The piezoelectric layer is at least partially disposed on the first electrode. The second electrode is at least partially disposed on the piezoelectric layer. The second electrode comprises an electrode body having an outer contour; and a plurality of protrusions protruding from the outer contour of the electrode body. Two adjacent ends of the plurality of protrusions are separated by a gap, and the gap exposes at least a portion of the piezoelectric layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] Figure 1 FIG. 4 is a schematic diagram of an acoustic wave device according to an embodiment of the present invention.

[0005] Figures 2 to 8 Schematic diagram of an acoustic wave device in many embodiments of the present invention.

[0006] Fig. 9 In one embodiment, Figure 1 Schematic cross-sectional view of the acoustic wave device along the cut line 9-9'.

[0007] Fig.10 In another embodiment, Figure 1 Schematic cross-sectional view of the acoustic wave device along the cut line 9-9'.

[0008] Explanation of symbols:

[0009] 1 to 8: Sound wave device

[0010] 10,14: Electrode

[0011] 12: Piezoelectric layer

[0012] 100,140: Electrode body

[0013] 100e,140e: Outer contour

[0014] 102,142: protrusion

[0015] 102e,142e: end

[0016] 103,143:Connection

[0017] 104,144: blocking part

[0018] 141,142: Surface

[0019] 16: Passivation layer

[0020] 18: Base

[0021] 90: Reflection part

[0022] 91 to 94: Lamination

[0023] 95: Cavity

[0024] G1, G2: Gap

[0025] h1,h2,h3: thickness

[0026] X,Y,Z: Direction DETAILED DESCRIPTION

[0027] Figure 1 Schematic diagram of an acoustic wave device 1 in one embodiment of the present invention. The acoustic wave device 1 may include a bulk acoustic wave (BAW) device, which can be used, for example, for a resonator, a filter, or other purposes. In some embodiments, the acoustic wave device 1 can be used as a BAW resonator, which can receive an input signal to generate a standing acoustic wave, and then convert the standing acoustic wave into a resonant signal. In other embodiments, the acoustic wave device 1 can be used as a BAW filter, which can receive an input signal from, for example, an antenna, and filter the received signal based on its frequency selectivity, thereby allowing signals of a specific frequency to pass. The use of the acoustic wave device 1 is only exemplified here, but the present invention is not limited to this.

[0028] In some embodiments, the acoustic wave device 1 may include an electrode 10, a piezoelectric layer 12, and an electrode 14. Figure 1As shown, the electrode 10 may be, for example, an upper electrode, and the electrode 14 may be, for example, a lower electrode. The piezoelectric layer 12 may be at least partially disposed on the electrode 10, and the electrode 14 may be at least partially disposed on the piezoelectric layer 12. In this embodiment, the overlapping area of ​​the electrode 10, the piezoelectric layer 12, and the electrode 14 may be referred to as an effective area, and the sound wave may be transmitted along the direction Z in the effective area. For example, the material of the electrode 10 or 14 may include a conductive material, such as molybdenum (Mo), copper (Cu), aluminum (Al), gold (Au), platinum (Pt), tungsten (W), other suitable metals, and combinations thereof. The material of the piezoelectric layer 12 may include, for example, at least one of the following: zinc oxide (ZnO), aluminum nitride (AlN), lithium tantalate (LiTaO3, LT), lithium niobate (LN), quartz (QZ), lead titanate (PTO), lead zirconate titanate (PZT) and the like, or a combination thereof. In some embodiments, the piezoelectric layer 14 may be doped with a rare earth element, such as scandium (Sc).

[0029] During operation, the electrode 10 can receive an input signal, the electrode 14 can be grounded, so as to generate an acoustic wave transmitted along the vertical direction Z, and the piezoelectric layer 12 can convert the acoustic wave into a resonant signal with a resonant frequency. The resonant frequency can depend on many parameters of the acoustic wave device 1, such as the material and thickness of the piezoelectric layer 12, the weight of the electrode 10 and the electrode 14, etc. For example, the range of the resonant frequency can be between 100 megahertz (MHz) and 20 gigahertz (GHz). Furthermore, the acoustic wave device 1 can also include a substrate (not shown) disposed under the electrode 14, wherein the material of the substrate can include, for example, silicon, glass, ceramic, gallium arsenide (Gallium Arsenide), and / or silicon carbide (Silicon carbide).

[0030] In this embodiment, the piezoelectric layer 12 may be stacked on the electrode 14, and the electrode 10 may be stacked on the piezoelectric layer 12. Figure 1 In the figure, the piezoelectric layer 12 and the electrode 14 have the same shape (e.g., circular) and size, but this is only for illustrative purposes and the present invention is not limited thereto. In other embodiments, the piezoelectric layer 12 and the electrode 14 may have different shapes or sizes. For example, the area of ​​the piezoelectric layer 12 (the size along the XY plane) may be larger than that of the electrode 14.

[0031] like Figure 1As shown, the electrode 10 may include an electrode body 100 and a plurality of protrusions 102, wherein the electrode body 100 has an outer contour 100e drawn with a dotted line, and the plurality of protrusions 102 may protrude and extend from the outer contour 100e of the electrode body 100, for example, extending to the end 102e of the protrusion 102. As shown in the figure, any one of the plurality of protrusions 102 is electrically connected to the electrode body 100. In some embodiments, a gap G1 is separated between the two ends of two adjacent ones of the plurality of protrusions 102, wherein the gap G1 may expose the piezoelectric layer 12 located below, for example, expose at least a portion of the piezoelectric layer 12. The plurality of protrusions 102 are not used to connect the electrode body 100 to other conductive elements. Compared with the electrode body 100, the plurality of protrusions 102 form an acoustic wave slow zone at the periphery, so as to confine energy as much as possible within the region of the electrode body 100, so as to reduce energy leakage, thereby suppressing the spurious mode and improving the quality factor of the acoustic wave device 1. In some embodiments, the end 102 e of one protrusion 102 is not in contact with or connected to the end 102 e of another protrusion 102 .

[0032] In some embodiments, the acoustic wave device 1 may further include a connection portion 103, which is electrically connected to the electrode 10 to achieve connection between the electrode 10 and other conductive elements. For example, the connection portion 103 may be disposed at the outer contour 100e of the electrode body 100 of the electrode 10. For example, the connection portion 103 may electrically connect the electrode body 100 to an external solder pad and / or solder ball to transmit a signal.

[0033] In some embodiments, the outer contour 100e of the electrode body 100 may include, for example, a polygon, a circle, an ellipse, an egg shape, or a truncated egg shape. Figure 1 and Figure 4 shown. Figure 1 The display electrode body 100 has a circular outer contour 100e. Figure 4 The electrode body 100 of the acoustic wave device 4 has an outer contour 100e of an egg shape or a cut-edge egg shape. Figure 4 In the embodiment, the egg-shaped outer contour 100e may have a relatively flat wide portion and a relatively sharp narrow portion. A straight line 4e may be formed between the wide portion and the narrow portion, for example, near the narrow portion, and the straight line 4e and the wide portion may together form the outer contour of the trimmed egg.

[0034] In some embodiments, the material of the protrusion 102 may be the same conductive material as the electrode body 100, such as molybdenum, and in this case, the protrusion 102 and the electrode body 100 may be formed as one piece, for example, the protrusion 102 and the electrode body 100 are formed of molybdenum in the same process step. However, in other embodiments, the material of the protrusion 102 may also be different from the conductive material of the electrode body 100, for example, the material of the protrusion 102 may be tungsten, and the material of the electrode body 100 may be molybdenum. In other embodiments, the material of the protrusion 102 may be a non-conductive material, such as a dielectric material such as ceramic, glass, or metal oxide.

[0035] exist Figure 1 In the acoustic wave device 1 shown, the plurality of protrusions 102 may have a substantially rectangular profile. It should be noted that the rectangular profile is not limited to a strictly defined rectangle, that is, the four sides of the profile of the protrusion 102 are not strictly straight sides. In detail, the protrusion 102 contacts the electrode body 100 at the outer profile 100e. Since the electrode body 100 may have a circular outer profile, the profile of the protrusion 102 may conform to the outer profile 100e of the electrode body 100 and be arc-shaped.

[0036] In some embodiments, at least one of the plurality of protrusions 102 may have the following profiles: rectangular, square, arc, circular, triangular, trapezoidal, or polygonal. Figures 1 to 3 shown.

[0037] exist Figure 2 In the acoustic wave device 2 shown, the protrusion 102 may have a substantially trapezoidal profile, which includes a long side in contact with the electrode body 100, two side sides, and a short side farther away from the electrode body 100. As shown in the figure, the long side of the trapezoidal profile may be an arc, and the short side may be a straight side. In some alternative embodiments, the positions of the long side and the short side may be interchangeable, in other words, the protrusion 102 may include a short side in contact with the electrode body 100, two side sides, and a long side farther away from the electrode body 100.

[0038] exist Figure 3 In the acoustic wave device 3 shown, the protrusion 102 may have an arc-shaped profile. In other embodiments not shown, the protrusion 102 may have a substantially triangular profile, which includes a vertex, two sides, and an arc-shaped bottom side, wherein the arc-shaped bottom side may contact the outer profile 100e of the electrode body 100. Alternatively, the vertex of the triangular profile may contact the outer profile 100e of the electrode body 100.

[0039] In the exemplary acoustic wave device shown in Figures 1 to 3, each of the multiple protrusions 102 has the same profile, but this is only for illustration. In other embodiments, each of the multiple protrusions 102 does not have to have the same profile, that is, the multiple protrusions 102 may, for example, include a first one having a rectangular profile and a second one having a trapezoidal profile.

[0040] In some embodiments, the plurality of protrusions 102 may be evenly distributed along the outer contour 100e of the electrode body 100. However, the present invention is not limited thereto. In other embodiments, the plurality of protrusions 102 may be unevenly distributed along the outer contour 100e. In this case, the plurality of protrusions 102 may be distributed only at a portion of the outer contour 100e. Figure 1 In the embodiment, the plurality of protrusions 102 are evenly distributed along most of the outer contour 100 e , and are unevenly distributed near the connecting portion 103 .

[0041] Figure 5 and Figure 6 The shapes of the electrodes 10 and 14 in other embodiments of the present invention are schematic diagrams, which can replace the electrodes 10 and 14 of the acoustic wave device 1 respectively. Figure 5 The electrode 10 and Figure 6 The structure of the electrode 14 is described in detail. It should be noted that Figure 5 The electrode 10 and the piezoelectric layer 12 are shown in FIG. Figure 6 The electrode 14 is shown in FIG.

[0042] exist Figure 5 In the figure, the electrode 10 of the acoustic wave device 5 may include an electrode body 100 having an outer contour 100e and a plurality of protrusions 102 protruding from the outer contour 100e. As shown in the figure, the plurality of protrusions 102 may be distributed only at a portion of the outer contour 100e (for example, half a circle), and may be evenly distributed within the portion. In this case, the two ends of two adjacent protrusions 102 are separated by a gap G1, and the gap G1 exposes the piezoelectric layer 12 below. In other embodiments, the plurality of protrusions 102 may be unevenly distributed at a portion of the outer contour 100e. In the above embodiment, the plurality of protrusions 102 form an acoustic wave slow zone (for example, a first acoustic wave slow zone) on the periphery of the electrode body 100, thereby suppressing the side wave mode.

[0043] exist Figure 6In the figure, the electrode 14 of the acoustic wave device 5 may include an electrode body 140 having an outer contour 140e and a plurality of protrusions 142 protruding from the outer contour 140e. As shown in the figure, the plurality of protrusions 142 may be distributed only at a portion of the outer contour 140e (for example, half a circle), and may be evenly distributed within the portion. In this case, a gap G2 is separated between the two ends of two adjacent protrusions 142. In other embodiments, the plurality of protrusions 142 may be unevenly distributed at a portion of the outer contour 140e. In the above embodiment, the plurality of protrusions 142 form an acoustic wave slow zone (for example, a second acoustic wave slow zone) on the periphery of the electrode body 140, thereby suppressing the secondary wave mode, and the contour shape and configuration of the plurality of protrusions 142 may be similar to the plurality of protrusions 102, which will not be described in detail here.

[0044] In some embodiments, Figure 5 The electrode 12 and the piezoelectric layer 14 of the embodiment can be Figure 6 The electrode 14 of the embodiment is used together. For example, Figure 5 The electrodes 12 and the piezoelectric layer 14 of the embodiment can be stacked along the direction Z. Figure 6 The electrode 14 of the embodiment of the present invention is formed on the plurality of protrusions 102 of the electrode 12 and the plurality of protrusions 142 of the electrode 14, and in the direction Z, the plurality of protrusions 102 of the electrode 12 and the plurality of protrusions 142 of the electrode 14 may not overlap. In this embodiment, the electrode body 100, the piezoelectric layer 12, and the electrode body 140 of the electrode 14 may overlap along the direction Z to form an effective area. Preferably, when projected onto the XY plane, the first acoustic wave slow zone formed by the plurality of protrusions 102 and the second acoustic wave slow zone formed by the plurality of protrusions 142 may partially overlap, or not overlap at all, so that the acoustic wave energy can be confined in the effective area as much as possible, thereby improving the quality factor of the acoustic wave device.

[0045] In other embodiments, when projected onto the XY plane, the plurality of protrusions 102 and the plurality of protrusions 142 may be staggered, for example, the projection of a protrusion 102 on the XY plane may correspond to the gap G2 between two adjacent protrusions 142. Vice versa, the projection of a protrusion 142 on the XY plane may correspond to the gap G1 between two adjacent protrusions 102, so that the acoustic wave energy can be confined within the effective area as much as possible, thereby improving the quality factor of the acoustic wave device.

[0046] Figure 5 A connecting portion 103 may be further included, which may be disposed on the outer contour 100 e of the electrode body 100 , for example, to achieve connection between the electrode 10 and other conductive elements. Figure 6 A connecting portion 143 may be further included, which may be disposed on the outer contour 140e of the electrode body 140 to achieve connection between the electrode 14 and other conductive elements, such as electrical connection with external pads and / or solder balls. In the direction Z, the connecting portion 103 and the connecting portion 143 at least partially do not overlap.

[0047] Figure 7 FIG. 1 is a schematic diagram of an acoustic wave device 7 according to another embodiment of the present invention. The main difference between the acoustic wave device 7 and the acoustic wave device 1 is that the acoustic wave device 7 further includes a blocking portion 104. The blocking portion 104 of the acoustic wave device 7 is described in detail below.

[0048] like Figure 7 As shown, the acoustic wave device 7 includes an electrode 10, a piezoelectric layer 12 and an electrode 14, wherein the electrode 10 may include an electrode body 100 and a plurality of protrusions 102. The electrode body 100 has an outer contour 100e drawn with a dotted line, and the plurality of protrusions 102 may protrude and extend from the outer contour 100e of the electrode body 100. In some embodiments, the acoustic wave device 7 also includes at least one blocking portion 104, which may be disposed on the piezoelectric layer 12 and may be located in a gap G1 between two adjacent protrusions 102. The blocking portion 104 may be electrically disconnected from the electrode body 100. Specifically, the blocking portion 104 may not contact the electrode body 100, but may be separated from the outer contour 100e of the electrode body 100 by a spacing. The contour of the blocking portion 104 may be a rectangle, a square, an arc, a triangle, a trapezoid, or a polygon. In the illustrated embodiment, the contour of each blocking portion 104 is a rectangle.

[0049] For example, the material of the blocking portion 104 includes a conductive material or a non-conductive material, and the material of the blocking portion 104 may be different from the material of the electrode body 100. In one embodiment, the material of the blocking portion 104 may be the same as the material of the electrode body 100, and may further be the same as the material of the protrusion 102, such as molybdenum. In this case, the electrode body 100, the protrusion 102, and the blocking portion 104 may be formed of molybdenum in the same process step. In another embodiment, the material of the blocking portion 104 may be different from the material of the electrode body 100, or different from the material of the protrusion 102, for example, the material of the electrode body 100 may be molybdenum, the material of the protrusion 102 may be molybdenum, and the material of the blocking portion 104 may be tungsten. In other embodiments, the material of the protrusion 102 may be a non-conductive material, for example, the material of the blocking portion 104 may be a dielectric material such as ceramic, glass, or metal oxide. It should be noted that in Figure 7 The connection portion 103 is omitted.

[0050] In the above embodiment, the blocking portion 104 is conducive to forming a slow sound wave zone at the periphery of the electrode body 100, so as to confine energy as much as possible within the area of ​​the electrode body 100, thereby further reducing energy leakage, thereby suppressing spurious modes and further improving the quality factor of the acoustic wave device 1.

[0051] Figure 8 FIG. 8 is a schematic diagram of an acoustic wave device 8 according to yet another embodiment of the present invention. Figure 8 The main difference between the acoustic wave device 8 and the acoustic wave device 5 is that the acoustic wave device 8 further includes a blocking portion 104 and a blocking portion 144. The blocking portion 104 and the blocking portion 144 of the acoustic wave device 8 are described in detail below. Figure 8 In FIG. 1 , the electrode 10 , the piezoelectric layer 12 , and the electrode 14 are shown separately.

[0052] As shown in the figure, in terms of the electrode 10, the blocking portion 104 may be disposed on the piezoelectric layer 12 and located in the gap G1 between two adjacent protrusions 102. In some embodiments, the blocking portion 104 may be electrically disconnected from the electrode body 100. In terms of the electrode 14, the blocking portion 144 may be located in the gap G2 between two adjacent protrusions 142. In some embodiments, the blocking portion 144 may be electrically disconnected from the electrode body 140.

[0053] The barrier 104 of the acoustic wave device 8 is similar to the barrier 104 of the acoustic wave device 7, and its description is not repeated here. The main difference between the barrier 144 of the acoustic wave device 8 and the barrier 104 is that the barrier 144 and the electrode 14 (e.g., the lower electrode) are arranged on substantially the same plane. Similarly, the material of the barrier 144 can be selected similarly to the barrier 104, for example, it can be a conductive material or a non-conductive material, and it is not repeated here in detail. In some embodiments, the outline of the barrier 144 can be a rectangle, a square, an arc, a triangle, a trapezoid, or a polygon. In the illustrated embodiment, the outline of each barrier 144 is a rectangle.

[0054] In at least one embodiment described above, taking the electrode 10 (eg, the upper electrode) as an example, the electrode body 100 may have a maximum size on the XY plane, and the protrusion 102 may also have a maximum size on the XY plane. Figure 1 For example, the maximum dimension of the electrode body 100 may be defined by the diameter of the circular outer contour 100e, and the maximum dimension of the protrusion 102 may be defined by the distance from the outer contour 100e to the end 102e of the protrusion in the radial direction. In some embodiments, the ratio of the maximum dimension of the protrusion 102 on the XY plane to the maximum dimension of the electrode body 100 on the XY plane may be, for example, between 0.05 and 1.0, for example, the ratio may be 0.1. It should be noted that the maximum dimension of the electrode body 100 or the protrusion 102 on the XY plane is not limited to the above embodiments. For example, in the case where the electrode body 100 or the protrusion 102 has a polygonal outer contour, its maximum dimension on the XY plane may be defined by the longest diagonal line. In the case where the electrode body 100 has an egg-shaped outer contour, its maximum dimension on the XY plane may be defined by the maximum distance from the wide part to the narrow part.

[0055] Fig. 9 In one embodiment, Figure 1 Schematic cross-sectional view of the acoustic wave device along the cut line 9-9' in FIG. As shown in the figure, the acoustic wave device, for example, includes a substrate 18, an electrode 14, a piezoelectric layer 12, an electrode 10, and a passivation layer 16 stacked in sequence. In detail, the passivation layer 16 can be disposed on the electrode 10, and it can at least cover the electrode body 100, the protrusion 102 and the connecting portion 103, thereby protecting the acoustic wave device 1. For example, the material of the passivation layer 16 can be silicon oxide (e.g., silicon dioxide) or silicon nitride (e.g., silicon nitride).

[0056] The electrode 14 may include a surface 141 (eg, an upper surface of the electrode 14 ) and a surface 142 (eg, a lower surface of the electrode 14 ), the substrate 18 is disposed on the surface 142 of the electrode 14 , and the piezoelectric layer 12 is disposed on the surface 141 of the electrode 14 .

[0057] In the illustrated embodiment, the substrate 18 may include a reflective portion 90, which may be disposed in the substrate 14, and in the direction Z, the reflective portion 90, the electrode 14, the piezoelectric layer 12, and the electrode 10 at least partially overlap. The reflective portion 90 may include, for example, a plurality of stacks, such as stacks 91 to 94. In this example, the stacks 91 to 94 may have different acoustic impedances to form a Bragg reflector to reduce leakage of acoustic waves. In the above embodiments, the number of stacks is only used for illustration and is not intended to limit the present invention.

[0058] like Fig. 9 As shown, in the electrode 10, in the direction Z, the electrode body 100 may have a thickness h1, and the protrusion 102 may have a thickness h2, wherein the thickness h2 may be greater than or equal to the thickness h1. It should be noted that the electrode 10 may include a plurality of protrusions 102, and the thickness of each protrusion 102 may be the same or different. For example, the plurality of protrusions 102 may include one with a thickness of h21 and another with a thickness of h22, wherein the thickness h21 may be different from the thickness h22. Further, the thickness h21 may be greater than the thickness h1 of the electrode body 100, and the thickness h22 may be less than the thickness h1 of the electrode body 100. In the above embodiment, protrusions of different thicknesses are conducive to forming an enhanced acoustic slow zone at the periphery of the electrode body 100. Specifically, the thicker protrusions may form an additional weight load at the periphery of the electrode body 100, further confining the energy within the region of the electrode body 100.

[0059] In addition, Fig. 9 It is also shown that the connecting portion 103 has a thickness h3, and the thickness h3 is greater than the thickness h1 of the electrode body 100. However, the present invention does not limit the thickness h3 of the connecting portion 103. In other embodiments, the thickness h3 of the connecting portion 103 may also be equal to or less than the thickness h1 of the electrode body 100.

[0060] Fig.10 In another embodiment, Figure 1 Schematic cross-sectional view of the acoustic wave device along the cut line 9-9'. Fig.10 and Fig. 9 The main difference is that unlike Fig. 9 In the stacked layers 91 to 94 , the reflecting portion 90 may include a cavity 95 .

[0061] exist Figures 1 to 10 In many acoustic wave devices, a slow acoustic wave zone can be formed on the periphery of the electrode body by configuring the protrusions and / or blocking parts, so as to confine the energy within the area of ​​the electrode body and reduce leakage, thereby suppressing the side wave mode and improving the quality factor of the acoustic wave device.

[0062] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the claims of the present invention should fall within the scope of the present invention.

Claims

1. An acoustic wave device, characterized in that: include: a first electrode; a piezoelectric layer at least partially disposed on the first electrode; and a second electrode, at least partially disposed on the piezoelectric layer, the second electrode comprising: a second electrode body having a second outer contour; and A plurality of second protrusions protrude from the second outer contour of the second electrode body, and two ends of two adjacent ones of the plurality of second protrusions are separated by a second gap, and the second gap exposes at least a portion of the piezoelectric layer.

2. The acoustic wave device according to claim 1, characterized in that A material of at least one of the plurality of second protrusions is different from a material of the second electrode body.

3. The acoustic wave device according to claim 1, characterized in that A thickness of at least one of the plurality of second protrusions in a vertical direction is greater than a thickness of the second electrode body in the vertical direction.

4. The acoustic wave device according to claim 1, characterized in that A ratio of a maximum dimension of at least one of the plurality of second protrusions on a horizontal plane to a maximum dimension of the second electrode body on the horizontal plane is between 0.05 and 1.

0.

5. The acoustic wave device according to claim 1, characterized in that The plurality of second protrusions are evenly distributed along at least a portion of the second outer contour of the second electrode body.

6. The acoustic wave device according to claim 1, characterized in that The plurality of second protrusions are unevenly distributed along at least a portion of the second outer contour of the second electrode body.

7. The acoustic wave device according to claim 1, characterized in that At least one of the plurality of second protrusions has the following contour: a rectangle, a square, an arc, a triangle, a trapezoid, or a polygon.

8. The acoustic wave device according to claim 7, characterized in that wherein one of the plurality of second protrusions has the trapezoidal profile, and the one of the plurality of second protrusions includes a short side, two side sides, and a long side, wherein the short side contacts the second outer contour of the second electrode body; or The long side contacts the second outer contour of the second electrode body.

9. The acoustic wave device according to claim 1, characterized in that It further includes at least one blocking portion, which is disposed on the piezoelectric layer and located in the second gap between two adjacent ones of the plurality of second protrusions.

10. The acoustic wave device according to claim 9, characterized in that The at least one blocking portion is electrically disconnected from the second electrode body.

11. The acoustic wave device according to claim 9, characterized in that A material of the at least one blocking portion is different from a material of the second electrode body.

12. The acoustic wave device according to claim 9, characterized in that The at least one blocking portion has a contour of a rectangle, a square, an arc, a triangle, a trapezoid, or a polygon.

13. The acoustic wave device according to claim 1, characterized in that The second outer contour of the second electrode body is a polygon, a circle, an ellipse, an egg, or a cut-edge egg.

14. The acoustic wave device according to claim 1, characterized in that The second electrode further comprises: A second connecting portion is disposed on the second outer contour of the second electrode body and is electrically connected to the second electrode body.

15. The acoustic wave device according to claim 14, characterized in that The first electrode comprises: a first electrode body having a first outer contour; and A plurality of first protrusions extending from the first outer contour and protruding from the first electrode body, wherein a first gap is spaced between two adjacent ones of the plurality of first protrusions; Wherein, in a vertical direction, the plurality of second protrusions and the plurality of first protrusions at least partially do not overlap.

16. The acoustic wave device according to claim 15, characterized in that The first electrode further comprises: a first connecting portion, disposed along the first outer contour of the first electrode body and electrically connected to the first electrode body; In a vertical direction, the second connection portion and the first connection portion at least partially do not overlap.

17. The acoustic wave device according to claim 15, characterized in that in: The plurality of second protrusions are distributed on a portion of the second outer contour; The plurality of first protrusions are distributed on a portion of the first outer contour; and The portion of the second outer contour and the portion of the first outer contour do not overlap.

18. The acoustic wave device according to claim 1, characterized in that in: The first electrode includes a first surface and a second surface, and the piezoelectric layer is disposed on the second surface of the first electrode; and The acoustic wave device further includes a substrate disposed on the first surface of the first electrode.

19. The acoustic wave device according to claim 18, characterized in that The substrate includes a reflective portion, which is disposed in the substrate and at least partially overlaps the first electrode, the piezoelectric layer, and the second electrode in a vertical direction.

20. The acoustic wave device according to claim 19, characterized in that The reflective portion includes a cavity and / or a plurality of stacked layers.

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