Bulk acoustic wave resonator and communication device

Abstract

The embodiment of the present invention discloses a bulk acoustic wave resonator and a communication device. The bulk acoustic wave resonator includes: a substrate, a sound reflection structure is arranged on the surface or inside of the substrate; a resonance unit, located on the side of the substrate where the sound reflection structure is arranged, the resonance unit includes a bottom electrode, a piezoelectric layer and a top electrode stacked in sequence, the top electrode includes an M-gon, the value of M is greater than or equal to 3, the top electrode has at least one first side, the projection of the first side on the substrate is located within the projection of the sound reflection structure on the substrate; the resonance unit also includes a top electrode connecting portion, the top electrode connecting portion is connected to the first side, and the total size of the contact between the top electrode connecting portion and the first side is less than the length of the first side. The technical solution provided by the embodiment of the present invention improves the electromechanical coupling coefficient of the bulk acoustic wave resonator while improving the quality factor of the bulk acoustic wave resonator.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of semiconductor technology, and in particular to a bulk acoustic wave resonator and a communication device. Background Art

[0002] In recent years, with the development of micro-electromechanical systems (MEMS) based on semiconductor micro-nano processing technology, bulk acoustic wave (BAW) resonators, as products in the MEMS field, play an important role in the field of wireless communications.

[0003] The main parameters of BAW resonators include the electromechanical coupling coefficient (Kt), etc. The electromechanical coupling coefficient quantifies the conversion efficiency between electrical energy and mechanical energy in the device. Existing BAW resonators have the problem of low electromechanical coupling coefficient. Summary of the invention

[0004] In view of this, an embodiment of the present invention provides a bulk acoustic wave resonator and a communication device to improve the electromechanical coupling coefficient of the bulk acoustic wave resonator.

[0005] An embodiment of the present invention provides a bulk acoustic wave resonator, comprising: a substrate, a surface or an interior of the substrate being provided with an acoustic reflection structure;

[0006] A resonance unit is located on a side of the substrate where the sound reflection structure is disposed, the resonance unit comprises a bottom electrode, a piezoelectric layer and a top electrode which are stacked in sequence, the top electrode comprises an M-gon, the value of M is greater than or equal to 3, the top electrode has at least one first side, and a projection of the first side on the substrate is located within a projection of the sound reflection structure on the substrate;

[0007] The resonance unit further includes a top electrode connecting portion, and a total size of a contact point between the top electrode connecting portion and the first side is smaller than a length of the first side.

[0008] Optionally, the top electrode connecting portion includes at least one sub-connecting portion.

[0009] Optionally, the bottom electrode includes an N-gon, the value of N is greater than or equal to 3, and part or all of the projection of the side of the bottom electrode corresponding to the first side on the substrate is located within the projection of the sound reflection structure on the substrate.

[0010] Optionally, an air gap structure is provided between the top electrode connecting portion and the piezoelectric layer.

[0011] Optionally, the edge of the bottom electrode corresponding to the first edge includes connected convex and concave portions, the projection of the concave portion on the substrate is located within the projection of the sound reflection structure on the substrate, and the projections of the convex portion and the at least one sub-connecting portion on the substrate have no overlap.

[0012] Optionally, a projection of an edge of the bottom electrode corresponding to the first edge on the substrate is located outside the projection of the first edge on the substrate.

[0013] Optionally, the shape of the convex portion includes at least one of a rectangular convex portion, an arc-shaped convex portion and a triangular convex portion;

[0014] And / or, the shape of the recess includes at least one of a rectangular groove, an arc-shaped groove and a triangular groove.

[0015] Optionally, a portion of the projection of the convex portion on the substrate is located outside the projection of the sound reflection structure on the substrate.

[0016] Optionally, the top electrode includes at least one second side, and the number of the second sides is greater than or equal to 1 and less than or equal to M-1;

[0017] The piezoelectric layer is provided with an isolation groove structure, wherein the isolation groove structure is provided on a surface of the piezoelectric layer away from the substrate and / or on a surface of the piezoelectric layer adjacent to the substrate;

[0018] And / or, the second side is provided with a microstructure for reducing shear wave propagation.

[0019] Optionally, the microstructure includes at least one of a cantilever structure, a protruding structure and a recessed structure.

[0020] Optionally, an insulating filling layer is further included, and the insulating filling layer is located in the isolation groove structure, and / or the insulating filling layer is located in the area between the cantilever structure and the piezoelectric layer.

[0021] Optionally, it further includes a supporting layer, which is located on the surface of the substrate and covers the sound reflection structure;

[0022] The bottom electrode is arranged on a surface of the support layer away from the substrate.

[0023] An embodiment of the present invention further provides a communication device, comprising the bulk acoustic wave resonator described in any of the above technical solutions;

[0024] The communication device includes at least one of a filter, a duplexer and a multiplexer.

[0025] In the technical solution provided by the embodiment of the present invention, the projection of the first side of the top electrode on the substrate is located within the projection of the acoustic reflection structure on the substrate; the top electrode connecting portion is connected to the first side, and the total size of the contact between the top electrode connecting portion and the first side is smaller than the length of the first side. On the first hand, the area of ​​the region where the top electrode connecting portion and the bottom electrode overlap is reduced, which reduces the value of the parallel capacitance formed by the top electrode connecting portion and the bottom electrode, thereby improving the electromechanical coupling coefficient of the bulk acoustic wave resonator. On the second hand, since the total size of the contact between the top electrode connecting portion and the first side is smaller than the length of the first side, the acoustic impedance of the first non-working area of ​​the resonance unit where the top electrode connecting portion is not provided does not match the acoustic impedance of the working area of ​​the resonance unit, so that the sound waves, especially the transverse waves, can be reflected back to the working area, reducing the loss of the sound waves, thereby improving the quality factor of the bulk acoustic wave resonator. In summary, the technical solution provided by the embodiment of the present invention improves the electromechanical coupling coefficient of the bulk acoustic wave resonator while improving the quality factor of the bulk acoustic wave resonator. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural schematic diagram of a bulk acoustic wave resonator in the prior art and a cross-sectional structural schematic diagram along the B1-B2 direction;

[0027] Figure 2 A top view of a bulk acoustic wave resonator provided by an embodiment of the present invention and a schematic cross-sectional structure diagram along the A1-A2 direction;

[0028] Figure 3 for Figure 2 A schematic diagram of the cross-sectional structure in the B1-B2 direction in the top view of the BAW resonator;

[0029] Figure 4 A top view of another BAW resonator provided by an embodiment of the present invention and a schematic cross-sectional structure diagram along the A1-A2 direction;

[0030] Figure 5 A top view of another BAW resonator provided by an embodiment of the present invention and a schematic cross-sectional structure diagram along the A1-A2 direction;

[0031] Figure 6 for Figure 5 A schematic diagram of the cross-sectional structure in the B1-B2 direction in the top view of the BAW resonator;

[0032] Figure 7 A top view of another BAW resonator provided by an embodiment of the present invention and a schematic cross-sectional structure diagram along the A1-A2 direction;

[0033] Figure 8 for Figure 7 A schematic diagram of the cross-sectional structure in the B1-B2 direction in the top view of the BAW resonator;

[0034] Fig. 9 A top view of another BAW resonator provided by an embodiment of the present invention and a schematic cross-sectional structure diagram along the A1-A2 direction;

[0035] Fig.10 for Fig. 9 A schematic diagram of the cross-sectional structure of the BAW resonator in the top view along the B1-B2 direction;

[0036] Fig.11 A top view of another BAW resonator provided by an embodiment of the present invention and a schematic cross-sectional structure diagram along the A1-A2 direction;

[0037] Fig.12 for Fig.11 A schematic diagram of the cross-sectional structure of the BAW resonator in the top view along the B1-B2 direction;

[0038] Fig.13 A top view of another BAW resonator provided by an embodiment of the present invention and a schematic cross-sectional structure diagram along the A1-A2 direction;

[0039] Fig.14 for Fig.13 A schematic diagram of the cross-sectional structure of the BAW resonator in the top view along the B1-B2 direction;

[0040] Fig.15 A top view of another BAW resonator provided by an embodiment of the present invention and a schematic cross-sectional structure diagram along the A1-A2 direction;

[0041] Fig.16 for Fig.15 A schematic diagram of the cross-sectional structure of the BAW resonator in the top view along the B1-B2 direction;

[0042] Fig.17 A top view of another BAW resonator provided by an embodiment of the present invention and a schematic cross-sectional structure diagram along the A1-A2 direction;

[0043] Fig.18 for Fig.17 A schematic diagram of the cross-sectional structure of the BAW resonator in the top view along the B1-B2 direction;

[0044] Fig.19 A top view of another BAW resonator provided by an embodiment of the present invention and a schematic cross-sectional structure diagram along the A1-A2 direction;

[0045] Fig. 20 for Fig.19 A schematic diagram of the cross-sectional structure of the BAW resonator in the top view along the B1-B2 direction;

[0046] Fig.21A top view of another BAW resonator provided by an embodiment of the present invention and a schematic cross-sectional structure diagram along the A1-A2 direction;

[0047] Fig. 22 for Fig.21 A schematic diagram of the cross-sectional structure of the BAW resonator in the top view along the B1-B2 direction;

[0048] Fig.23 A top view of another BAW resonator provided by an embodiment of the present invention and a schematic cross-sectional structure diagram along the A1-A2 direction;

[0049] Fig.24 for Fig.23 Schematic diagram of the cross-sectional structure along the B1-B2 direction in the top view of the BAW resonator. DETAILED DESCRIPTION

[0050] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0051] As described in the above background technology, the inventors have found through careful research that the existing BAW resonator has the problem of low electromechanical coupling coefficient. Figure 1 Schematic diagram of the structure of a BAW resonator in the prior art and a schematic diagram of the cross-sectional structure along the B1-B2 direction. Figure 1 , the BAW resonator includes a substrate 10, an acoustic reflection structure 20 is arranged inside the substrate 10, wherein the resonance unit 30 includes a bottom electrode 31, a piezoelectric layer 32 and a top electrode 33 which are stacked in sequence. The resonance unit 30 also includes a top electrode connecting portion 34. The top electrode connecting portion 34 is connected to the first side 330 of the top electrode 33, and the total size L1 of the contact between the top electrode connecting portion 34 and the first side 330 is equal to the length L2 of the first side 330. The bottom electrode 31 and the top electrode connecting portion 34 located outside the working area 30A constitute a parallel capacitor, so that the BAW resonator has a relatively low electromechanical coupling coefficient. It should be noted that the projections of the stacked bottom electrode 31, the piezoelectric layer 32 and the top electrode 33 on the substrate 10 overlap, and the part of the projection located within the projection of the acoustic reflection structure 20 on the substrate 10 belongs to the working area 30A of the resonance unit 30. The contact point between the top electrode connecting portion 34 and the first side 330 is the side 343 where the top electrode connecting portion 34 contacts the first side 330. The total dimension L1 of the contact point between the top electrode connecting portion 34 and the first side 330 is the total dimension of the side 343 where the top electrode connecting portion 34 contacts the first side 330 in the extension direction parallel to the first side 330. The extension direction of the first side 330 is the Y direction in the plane coordinate system XOY.

[0052] In view of the above technical problems, the embodiments of the present invention provide the following technical solutions:

[0053] Figure 2 A top view and a schematic cross-sectional structure diagram along the A1-A2 direction of a bulk acoustic wave resonator provided in an embodiment of the present invention. Figure 3 for Figure 2 Schematic diagram of the cross-sectional structure along the B1-B2 direction in the top view of the BAW resonator. Figure 2 and Figure 3 The BAW resonator comprises: a substrate 10, a sound reflection structure 20 is arranged on the surface or inside of the substrate 10; a resonance unit 30, which is located on the side of the substrate 10 where the sound reflection structure 20 is arranged, and the resonance unit 30 comprises a bottom electrode 31, a piezoelectric layer 32 and a top electrode 33 which are stacked in sequence, the top electrode 33 comprises an M-gon, the value of M is greater than or equal to 3, the top electrode 33 has at least one first side 330, and the projection of the first side 330 on the substrate 10 is located within the projection of the sound reflection structure 20 on the substrate 10; the resonance unit 30 also comprises a top electrode connecting portion 34, the top electrode connecting portion 34 is connected to the first side 330, and the total size of the contact between the top electrode connecting portion 34 and the first side 330 is less than the length L2 of the first side 330.

[0054] It should be noted that the contact point between the top electrode connecting portion 34 and the first side 330 is the side 343 where the top electrode connecting portion 34 contacts the first side 330. The total size of the contact point between the top electrode connecting portion 34 and the first side 330 is the total size of the side 343 where the top electrode connecting portion 34 contacts the first side 330 in the extension direction parallel to the first side 330. The extension direction of the first side 330 is the Y direction in the plane coordinate system XOY.

[0055] For example, Figure 2 The total size of the contact point between the top electrode connecting portion 34 and the first side 330 is the sum of the first size L10 and the second size L11 .

[0056] In the embodiment of the present invention, the top electrode 33 including one first edge 330 is taken as an example for description, but the embodiment of the present invention also includes a technical solution in which the number of the first edges 330 is greater than one.

[0057] Exemplarily, in the embodiment of the present invention, the value of M is 5, but it is not limited thereto. It should be noted that the embodiment of the present invention does not limit the shape of the piezoelectric layer 32. The shape of the piezoelectric layer 32 is not a pentagon. The piezoelectric layer 32 is laid flat on the substrate 10 and covers the bottom electrode 31. The bottom electrode 31, the piezoelectric layer 32 and the top electrode 33 form a sandwich structure.

[0058] It should be noted that in the embodiment of the present invention, the resonance unit 30 is divided into a working area 30A and a non-working area, and the non-working area includes a first non-working area 30B1 and a second non-working area 30B2. Specifically, the projections of the bottom electrode 31, the piezoelectric layer 32 and the top electrode 33 stacked in sequence overlap on the substrate 10, and the part of the projection located within the projection of the acoustic reflection structure 20 on the substrate 10 belongs to the working area 30A of the resonance unit 30. The part of the resonance unit 30 outside the working area 30A is called the non-working area. In the first non-working area 30B1, the top electrode connecting portion 34 is connected to the first edge 330 whose projection is located within the projection of the acoustic reflection structure 20 on the substrate 10. Since the total size of the contact point between the top electrode 34 and the first edge 330 is less than the length L2 of the first edge 330, the area of ​​the region where the top electrode connecting portion 34 and the bottom electrode 31 overlap is reduced, which reduces the value of the parallel capacitance formed by the top electrode connecting portion 34 and the bottom electrode 31, thereby improving the electromechanical coupling coefficient of the bulk acoustic wave resonator.

[0059] The main parameters of the BAW resonator also include the quality factor (Q value). The quality factor is a key indicator to describe the performance of the BAW resonator, and directly determines the value of the device. In the embodiment of the present invention, the most basic structure of the BAW resonator is a sandwich structure composed of the bottom electrode 31, the piezoelectric layer 32 and the top electrode 33. Under the action of the alternating electric field of the bottom electrode 31 and the top electrode 33, the piezoelectric layer 32 will deform, which is manifested as the vibration of phonons at the microscopic level, and forms a sound wave vibrating in the piezoelectric layer 32 at the macroscopic level. The sound wave vibrates in the piezoelectric layer 32 to form a standing wave, which is mainly in the form of a longitudinal wave, but there will still be a small amount of transverse waves. In the longitudinal wave, the direction of movement of the particle is parallel to the direction of propagation of the sound wave, but each particle will not move along the direction of the sound wave, but will only vibrate back and forth in its own equilibrium state. In the transverse wave, the direction of movement of the particle and the direction of propagation of the sound wave are perpendicular to each other. The particle will not move along the direction of propagation of the sound wave, but will only vibrate up and down in its own equilibrium state. In the embodiment of the present invention, the longitudinal waves in the sound waves of the resonance unit 30 mainly propagate in a thickness direction parallel to the substrate 10. The transverse waves in the sound waves of the resonance unit 30 mainly propagate in a thickness direction perpendicular to the substrate 10. The sound reflection structure 20 is mainly used to reflect the longitudinal waves in the sound waves back to the resonance unit 30 to improve the quality factor of its bulk acoustic wave resonator. The sound reflection structure 20 can be formed inside the substrate 10 or on the surface of the substrate 10. When formed on the surface of the substrate 10, it can be realized by a supporting structure, which is not described in detail here. This embodiment is described as being formed inside the substrate 10.

[0060] In the above technical solution, the total size of the contact point between the top electrode connecting portion 34 and the first edge 330 is smaller than the length L2 of the first edge 330, so that the acoustic impedance of the first non-working area 30B1 of the resonance unit 30 where the top electrode connecting portion 34 is not set does not match the acoustic impedance of the working area 30A of the resonance unit 30. The first non-working area 30B1 can reflect sound waves, especially transverse waves, back to the working area 30A, reducing the loss of sound waves and thereby improving the quality factor of the bulk acoustic wave resonator.

[0061] According to the technical solution provided by the embodiment of the present invention, the projection of the first side 330 of the top electrode 33 on the substrate 10 is located within the projection of the acoustic reflection structure 20 on the substrate 10; the top electrode connecting portion 34 is connected to the first side 330, and the total size of the contact between the top electrode connecting portion 34 and the first side 330 is less than the length L2 of the first side 330. On the first hand, the area of ​​the overlapping region of the top electrode connecting portion 34 and the bottom electrode 31 is reduced, which reduces the value of the parallel capacitance formed by the top electrode connecting portion 34 and the bottom electrode 31, thereby improving the electromechanical coupling coefficient of the bulk acoustic wave resonator. On the second hand, since the total size of the contact between the top electrode connecting portion 34 and the first side 330 is less than the length L2 of the first side 330, the acoustic impedance of the first non-working region 30B1 of the resonance unit 30 where the top electrode connecting portion 34 is not provided does not match the acoustic impedance of the working region 30A of the resonance unit 30, so that the acoustic wave, especially the transverse wave, can be reflected back to the working region 30A, reducing the loss of the acoustic wave, thereby improving the quality factor of the bulk acoustic wave resonator. In summary, the technical solution provided by the embodiment of the present invention improves the electromechanical coupling coefficient of the BAW resonator while improving the quality factor of the BAW resonator.

[0062] Optional, see Figure 2 and Figure 3 , the top electrode connection portion 34 includes at least one sub-connection portion. Exemplarily, Figure 2 and Figure 3 In the embodiment, the top electrode connection portion 34 includes a sub-connection portion 340 , a sub-connection portion 341 and a sub-connection portion 342 .

[0063] It should be noted that Figure 2 and Figure 3 Two sub-connecting parts 340 and 342 are arranged in parallel, and a sub-connecting part 341 is shown for connecting the sub-connecting part 340 and the sub-connecting part 342. After the sub-connecting part 341 is connected to the electrical signal, the electrical signal can be transmitted to the spaced sub-connecting part 340 and the sub-connecting part 342. In a specific application process, only the spaced sub-connecting part 340 and the sub-connecting part 342 can be arranged, and the spaced sub-connecting part 340 and the sub-connecting part 342 can be connected to the electrical signal respectively. And there is no limit on the number of the spaced sub-connecting parts 340 and the sub-connecting part 342.

[0064] Specifically, the top electrode connection portion 34 includes at least one sub-connection portion, which further reduces the area of ​​the top electrode connection portion 34 compared to the top electrode connection portion 34 which is an integral structure, thereby reducing the value of the parallel capacitance formed by the top electrode connection portion 34 and the bottom electrode 31, thereby further improving the electromechanical coupling coefficient of the BAW resonator.

[0065] In order to further improve the quality factor and electromechanical coupling coefficient of the BAW resonator, the structure of the bottom electrode 31 is improved in the embodiment of the present invention.

[0066] Optional, see Figure 5 and Figure 6 as well as Figure 7 and Figure 8 The bottom electrode 31 includes an N-gon, the value of N is greater than or equal to 3, and part or all of the projection of the side 310 corresponding to the first side 330 of the bottom electrode 31 on the substrate 10 is located within the projection of the sound reflection structure 20 on the substrate 10.

[0067] Exemplarily, in the embodiment of the present invention, the value of N is 5, but is not limited thereto. In the embodiment of the present invention, the side 310 corresponding to the bottom electrode 31 and the first side 330 is arranged parallel to the first side 330 .

[0068] For example, Figure 5 and Figure 6 In the embodiment, the projection of the side 310 of the bottom electrode 31 corresponding to the first side 330 on the substrate 10 is located within the projection of the sound reflection structure 20 on the substrate 10 . Figure 6 and Figure 7 In the embodiment, the projections of the bottom electrode 31 and the edges 310 corresponding to the first edges 330 on the substrate 10 are all located within the projection of the sound reflection structure 20 on the substrate 10 .

[0069] Specifically, part or all of the projection of the edge 310 corresponding to the bottom electrode 31 and the first edge 330 on the substrate 10 is located within the projection of the sound reflection structure 20 on the substrate 10, thereby reducing the area of ​​the bottom electrode 31 in the first non-working area 30B1, making the acoustic impedance of the first non-working area 30B1 of the resonance unit 30 mismatched with the acoustic impedance of the working area 30A of the resonance unit 30, and reflecting the sound waves, especially the transverse waves, back to the working area 30A, reducing the loss of the sound waves, thereby further improving the quality factor of the bulk acoustic wave resonator.

[0070] Optional, see Figure 4 , Figure 7 and Fig. 9 In the BAW resonator, an air gap structure 301 is provided between the top electrode connecting portion 34 and the piezoelectric layer 32 .

[0071] Specifically, there is an air gap structure 301 between the top electrode connecting portion 34 and the piezoelectric layer 32. The air gap structure 301 can reflect the sound waves, especially the transverse waves, back to the working area 30A of the resonance unit 30, reducing the loss of the sound waves and further improving the quality factor of the BAW resonator.

[0072] Optional, see Figure 5 and Figure 6 The bottom electrode 31 includes an M-gon, and the side 310 of the bottom electrode 31 corresponding to the first side 330 includes a connected convex portion 3101 and a concave portion 3102, the projection of the concave portion 3102 on the substrate 10 is located within the projection of the sound reflection structure 20 on the substrate 10, and the projection of the convex portion 3101 and at least one sub-connecting portion on the substrate 10 has no overlap.

[0073] Specifically, Figure 5 and Figure 6 In the BAW resonator shown in FIG, the projection of the concave portion 3102 included in the edge 310 corresponding to the bottom electrode 31 and the first edge 330 on the substrate 10 is located within the projection of the acoustic reflection structure 20 on the substrate 10, reducing the area of ​​the bottom electrode 31 in the first non-working area 30B1, so that the acoustic impedance of the first non-working area 30B1 of the resonance unit 30 and the acoustic impedance of the working area 30A of the resonance unit 30 do not match, and the sound waves, especially the transverse waves, can be reflected back to the working area 30A, reducing the loss of the sound waves, thereby further improving the quality factor of the BAW resonator. In addition, the provision of the concave portion 3102 further reduces the value of the parallel capacitance formed by the bottom electrode 31 and the top electrode connecting portion 34, further improving the electromechanical coupling coefficient of the BAW resonator. See FIG. Figure 5 and Figure 6 The projection of the protrusion 3101 on the substrate 10 and the projection of at least one sub-connection portion on the substrate 10 do not overlap, thereby avoiding the situation where the protrusion 3101 and the top electrode connection portion 34 form a parallel capacitor, further improving the electromechanical coupling coefficient of the bulk acoustic wave resonator.

[0074] Figure 7 and Figure 8 The BAW resonator shown, and Figure 5 and Figure 6 Compared with the BAW resonator shown, the edge 310 corresponding to the bottom electrode 31 and the first edge 330 is not provided with the recess 3102 and the protrusion 3101, and the projection of the edge 310 corresponding to the bottom electrode 31 and the first edge 330 on the substrate 10 is completely located within the projection of the sound reflection structure 20 on the substrate 10, which further reduces the area of ​​the bottom electrode 31 in the first non-working region 30B1, thereby further improving the quality factor and electromechanical coupling coefficient of the BAW resonator.

[0075] Optional, Figure 5In the embodiment, the recess 3102 and the edge of the sound reflection structure 20 are spaced apart by a preset distance W. Figure 7 and Figure 8 The first side 330 and the edge of the sound reflection structure 20 are separated by a preset distance W, which reduces the area of ​​the bottom electrode 31 in the first non-working area 30B1, thereby further improving the quality factor and electromechanical coupling coefficient of the BAW resonator. The preset distance W is greater than or equal to 0.2 microns and less than or equal to 10 microns. When the preset distance W is too small, that is, less than 0.2 microns, the difficulty of the preparation process is increased. When the preset distance W is too large, that is, greater than 10 microns, the area of ​​the piezoelectric layer 32 is wasted, and the preparation cost of the BAW resonator is increased. Preferably, the preset distance is greater than or equal to 0.5 microns and less than or equal to 3 microns.

[0076] Optionally, a projection of the side 310 of the bottom electrode 31 corresponding to the first side 330 on the substrate 10 is located outside the projection of the first side 330 on the substrate 10 .

[0077] For example, see Figure 5 and Figure 6 , the projection of the concave portion 3102 on the substrate 10 is located outside the projection of the first edge 330 on the substrate 10. For example, see Figure 7 and Figure 8 , the projection of the side 310 of the bottom electrode 31 corresponding to the first side 330 on the substrate 10 is located outside the projection of the first side 330 on the substrate 10 .

[0078] Specifically, the projection of the edge 310 of the bottom electrode 31 corresponding to the first edge 330 on the substrate 10 is located outside the projection of the first edge 330 on the substrate 10, which can be used to support the piezoelectric layer 32, thereby avoiding the problem of the piezoelectric layer 32 collapsing from the substrate 10 due to excessive stress, thereby improving the structural stability of the bulk acoustic wave resonator.

[0079] Optional, see Figure 5 and Figure 6 The projection of the protrusion 3101 on the substrate 10 is located outside the projection of the sound reflection structure 20 on the substrate 10 .

[0080] Specifically, the projection of the protrusion 3101 on the substrate 10 is located outside the projection of the sound reflection structure 20 on the substrate 10, which can be used to support the piezoelectric layer 32, avoiding the problem of the piezoelectric layer 32 collapsing from the substrate 10 due to excessive stress, thereby enhancing the structural stability of the bulk acoustic wave resonator.

[0081] Optionally, the shape of the convex portion 3101 includes at least one of a rectangular convex portion, an arc-shaped convex portion and a triangular convex portion; and / or the shape of the concave portion 3102 includes at least one of a rectangular groove, an arc-shaped groove and a triangular groove.

[0082] For example, Figure 5 and Figure 6 In the embodiment, the specific shape of the protrusion 3101 is a rectangular protrusion, and the shape of the concave portion 3102 includes a rectangular groove.

[0083] Specifically, the shape of the protrusion 3101 includes at least one of a rectangular protrusion, an arc-shaped protrusion and a triangular protrusion; and / or the shape of the concave portion 3102 includes at least one of a rectangular groove, an arc-shaped groove and a triangular groove, which enriches the specific shapes of the protrusion 3101 and the concave portion 3102 and increases the flexibility of the setting scheme of the protrusion 3101 and the concave portion 3102.

[0084] In order to further improve the quality factor of the BAW resonator, the embodiment of the present invention also improves the structure of the top electrode 33 and the piezoelectric layer 32. Figure 9-Figure 16 A modification to the piezoelectric layer 32 is shown. Figure 17-Figure 20 A modification to the top electrode 33 is shown.

[0085] Optional, see Figure 9-Figure 16 , the top electrode 33 includes at least one second side 331, the number of the second sides 331 is greater than or equal to 1 and less than or equal to M-1; the piezoelectric layer 32 is provided with an isolation groove structure 32A, wherein the isolation groove structure 32A is provided on the surface of the piezoelectric layer 32 away from the substrate 10 and / or the surface of the piezoelectric layer 32 adjacent to the substrate 10. And / or, see Figure 17-Figure 20 The second side 311 is provided with a microstructure 33A for reducing the propagation of shear waves.

[0086] It should be noted that the top electrode 33 is composed of a first side 330 and a second side 331 , that is, the side excluding the first side 330 is the second side 331 .

[0087] It should also be noted that the isolation groove structure 32A may or may not overlap with the second side 331 of the top electrode 33. The embodiment of the present invention exemplarily shows a technical solution in which the isolation groove structure 32A may not overlap with the second side 331 of the top electrode 33.

[0088] For example, Figure 9-12 In the embodiment, the piezoelectric layer 32 is provided with an isolation groove structure 32A, wherein the isolation groove structure 32A is provided on the surface of the piezoelectric layer 32 away from the substrate 10, so that the acoustic impedance of the second non-working area 30B2 of the resonance unit 30 is mismatched with the acoustic impedance of the working area 30A of the resonance unit 30, and the sound waves, especially the transverse waves, can be reflected back to the working area 30A, reducing the loss of the sound waves, thereby further improving the quality factor of the bulk acoustic wave resonator. In addition, the isolation groove structure 32A can eliminate the parasitic structure of the top electrode 33.

[0089] For example, Figure 13-Figure 16 In the embodiment, the piezoelectric layer 32 is provided with an isolation groove structure 32A, wherein the isolation groove structure 32A is provided on the surface of the piezoelectric layer 32 adjacent to the substrate 10, so that the acoustic impedance of the second non-working area 30B2 of the resonance unit 30 does not match the acoustic impedance of the working area 30A of the resonance unit 30, and the sound waves, especially the transverse waves, can be reflected back to the working area 30A, reducing the loss of the sound waves, thereby further improving the quality factor of the bulk acoustic wave resonator. In addition, the isolation groove structure 32A can eliminate the parasitic structure of the bottom electrode 31.

[0090] It should be noted that an embodiment of the present invention also includes a technical solution in which, in a bulk acoustic wave resonator, the piezoelectric layer 32 is provided with an isolation groove structure 32A, wherein the isolation groove structure 32A is provided on the surface of the piezoelectric layer 32 away from the substrate 10 and on the surface of the piezoelectric layer 32 adjacent to the substrate 10.

[0091] See also Figure 17-Figure 20 The second side 311 is provided with a microstructure 33A, and the microstructure 33A can reflect the transverse wave in the sound wave back to the working area 30A, thereby reducing the loss of the sound wave and further improving the quality factor of the BAW resonator.

[0092] Optional, see Figure 17-Figure 20 The microstructure 33A includes at least one of a cantilever structure 33a1, a protruding structure 33a2, and a recessed structure 33a3.

[0093] Specifically, the cantilever structure 33a1 is provided so that there is an air gap with an acoustic impedance of 0 between the top electrode 33 and the piezoelectric layer 32, thereby making the impedance of the second non-working area 30B2 and the working area 30A mismatched, and the transverse waves in the sound waves can be reflected back to the working area 30A, reducing the loss of the sound waves, thereby further improving the quality factor of the bulk acoustic wave resonator. In addition, the cantilever structure 33a1 is provided so that there is an air gap with an acoustic impedance of 0 between the second side of the top electrode 33 and the piezoelectric layer 32, which can eliminate the parasitic structure of the top electrode 33.

[0094] The raised structure 33a2 constitutes a raised reflective structure, and the recessed structure 33a3 constitutes a recessed reflective structure, which are structures for avoiding the loss of acoustic wave energy, so as to achieve the effect of reflecting the bulk acoustic wave back to the piezoelectric layer 32, reduce the loss of the acoustic wave, and further improve the quality factor of the bulk acoustic wave resonator. It should be noted that the raised structure 33a2 and the recessed structure 33a3 are not limited to being located on the surface of the top electrode 33 away from the piezoelectric layer 32, but can also be located on the surface of the top electrode 33 adjacent to the piezoelectric layer 32. When the raised structure 33a2 and the recessed structure 33a3 are located on the surface of the top electrode 33 adjacent to the piezoelectric layer 32, there is an air gap with an acoustic impedance of 0 between the raised structure 33a2 and the recessed structure 33a3 and the piezoelectric layer 32, which can eliminate the parasitic structure of the top electrode 33.

[0095] The embodiment of the present invention also includes a technical solution in which, in a BAW resonator, an edge 320 of the piezoelectric layer 32 corresponding to the second edge 331 is provided with an isolation groove structure 32A, and a second edge 331 of the top electrode 33 is provided with a microstructure 33A.

[0096] Optional, see Fig.11 and Fig.12 , Fig.15 and Fig.16 as well as Fig.19 and Fig. 20 , further comprising an insulating filling layer 40 , the insulating filling layer 40 being located in the isolation groove structure 32A, and / or the insulating filling layer 40 being located in a region between the cantilever structure 33 a 1 and the piezoelectric layer 32 .

[0097] For example, Fig.11 and Fig.12 as well as Fig.15 and Fig.16 The insulating filling layer 40 is located in the isolation groove structure 32A. Fig.19 and Fig. 20 In the embodiment, the insulating filling layer 40 is located in the region between the cantilever structure 33a1 and the piezoelectric layer 32. The insulating filling layer 40 can eliminate the parasitic structure of the bottom electrode 31 and / or the top electrode 33. Exemplarily, the insulating filling layer 40 includes non-piezoelectric materials such as silicon dioxide, silicon nitride, silicon carbide, and various metal oxides or epoxy resins.

[0098] It should be noted that in a bulk acoustic wave resonator in which the piezoelectric layer 32 is provided with an isolation groove structure 32A and the second edge 331 of the top electrode 33 is provided with a cantilever structure 33a1, the insulating filling layer 40 can be located in the isolation groove structure 32A and in the area between the cantilever structure 33a1 and the piezoelectric layer 32.

[0099] Optional, see Figure 7-Figure 20, further comprising a supporting layer 50 , the supporting layer 50 being located between the substrate 10 and the resonance unit 30 and covering the sound reflection structure 20 ; the bottom electrode 31 being arranged on a surface of the supporting layer 50 away from the substrate 10 .

[0100] Specifically, the support layer 50 can be made of an insulating material, such as aluminum nitride. In the prior art, the seed layer and the bottom electrode 31 are grown continuously, and then the bottom electrode 31 and the seed layer are patterned at the same time, and the seed layer is located between the bottom electrode 31 and the substrate 10. In the embodiment of the present invention, while the bottom electrode 31 is patterned, the support layer 50 is not patterned. The support layer 50 can support the bottom electrode 31 to prevent the bottom electrode 31 from collapsing from the substrate 10 due to excessive stress, thereby enhancing the structural stability of the bulk acoustic wave resonator.

[0101] Optional, see Figure 2-Figure 24 The sound reflection structure 20 includes any one of a cavity structure 20a, a Bragg reflection layer 20b and a back surface groove 20c.

[0102] It should be noted that Figure 2-Figure 20 In the description, the cavity structure 20a is taken as an example of the sound reflection structure 20. Fig.21 and Fig. 22 In the description, the Bragg reflection layer 20 b is taken as an example of the sound reflection structure 20 . Fig.23 and Fig.24 In the embodiment, the back groove 20c is taken as an example of the sound reflection structure 20 for introduction. The back groove 20c can be a conical groove or a groove of equal diameter.

[0103] For example, Figure 2-Figure 20 The cavity structure 20a and Fig.23 and Fig.24 What is shown in the figure is that in the back groove 20c, since the acoustic impedance of air is close to 0, while the acoustic impedance of the resonance unit 30 is relatively large, this interface acoustic impedance mismatch causes the sound waves, especially the longitudinal waves, transmitted to the cavity structure 20a or the back groove 20c to be almost completely reflected back to the resonance unit 30, so that the energy of the sound waves leaking out of the resonance unit 30 is extremely small, thereby preventing the sound waves of the resonance unit 30 from leaking to the substrate 10. Fig.21 and Fig. 22It is shown that the Bragg reflection layer 20b is formed by alternately stacking high and low acoustic impedance layers to prevent the sound waves of the resonance unit 30 from leaking to the substrate 10. The thickness of each acoustic impedance layer is greater than 1 / 4 wavelength. The greater the acoustic impedance ratio of the high and low acoustic impedance layers, the better the effect of the Bragg reflection layer 20b in preventing the sound waves of the resonance unit 30 from leaking to the substrate 10. Specifically, compared with the technical solution of the Bragg reflection layer 20b and the back groove 20c as the acoustic reflection structure 20, the cavity structure 20a as the body acoustic wave resonator of the acoustic reflection structure 20 has the characteristics of higher quality factor and higher electromechanical coupling coefficient. Optionally, Fig.21 and Fig. 22 The BAW resonator shown in FIG. 1 further includes an insulating support functional layer 60 for supporting the resonance unit 30 .

[0104] Optionally, the projection of the first side 330 of the top electrode 33 on the substrate 10 extends to outside the projection of the acoustic reflection structure 20 on the substrate 10, so as to form an interconnection structure with an external connection structure, and obtain the electrical signal required by the top electrode 33 from the external connection structure. The projection of the side of the bottom electrode 31 opposite to the second side 331 of the top electrode 33 on the substrate 10 extends to outside the projection of the acoustic reflection structure 20 on the substrate 10, so as to form an interconnection structure with an external connection structure, and obtain the electrical signal required by the bottom electrode 31 from the external connection structure. Optionally, the side of the bottom electrode 31 opposite to the second side 331 of the top electrode 33 is arranged parallel to the second side 331.

[0105] Optionally, the projection of the second side 331 of the top electrode 33 on the substrate 10 is located within the projection of the sound reflection structure 20 on the substrate 10, reducing the value of the parallel capacitance of the resonance unit 30 in the second non-working area 30B2 and further improving the electromechanical coupling coefficient of the BAW resonator.

[0106] An embodiment of the present invention further provides a communication device, comprising any BAW resonator described in the above technical solutions; the communication device comprises at least one of a filter, a duplexer and a multiplexer.

[0107] Specifically, a duplexer can be simply understood as the operation of two BAW filters, one is a receiving BAW filter to receive signals, and the other is a transmitting BAW filter to transmit signals. A multiplexer can be simply understood as a communication device composed of at least two duplexers.

[0108] The communication device provided in the embodiment of the present invention includes the bulk acoustic wave filter as described in any of the above technical solutions, and therefore has the beneficial effects of the above bulk acoustic wave filter, which will not be described in detail here.

[0109] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A bulk acoustic wave resonator, characterized in that: include: A substrate, wherein a sound reflection structure is arranged on the surface or inside of the substrate; A resonance unit is located on a side of the substrate where the sound reflection structure is disposed, the resonance unit comprises a bottom electrode, a piezoelectric layer and a top electrode which are stacked in sequence, the top electrode comprises an M-gon, the value of M is greater than or equal to 3, the top electrode has at least one first side, and a projection of the first side on the substrate is located within a projection of the sound reflection structure on the substrate; The resonance unit further includes a top electrode connecting portion, the top electrode connecting portion is connected to the first side, and a total size of a contact point between the top electrode connecting portion and the first side is smaller than a length of the first side; The top electrode connection portion includes at least one sub-connection portion; The bottom electrode comprises an N-sided polygon, the value of N is greater than or equal to 3, and part or all of the projection of the side of the bottom electrode corresponding to the first side on the substrate is located within the projection of the sound reflection structure on the substrate; The side of the bottom electrode corresponding to the first side includes a connected convex portion and a concave portion, the projection of the concave portion on the substrate is located within the projection of the sound reflection structure on the substrate, and the projection of the convex portion and the projection of the at least one sub-connecting portion on the substrate do not overlap.

2. The bulk acoustic wave resonator according to claim 1, characterized in that An air gap structure is provided between the top electrode connecting portion and the piezoelectric layer.

3. The bulk acoustic wave resonator according to claim 1, characterized in that: The projection of the side of the bottom electrode corresponding to the first side on the substrate is located outside the projection of the first side on the substrate.

4. The bulk acoustic wave resonator according to claim 1, characterized in that The portion of the projection of the convex portion on the substrate is located outside the projection of the sound reflecting structure on the substrate.

5. The bulk acoustic wave resonator according to claim 1, characterized in that: The shape of the convex portion includes at least one of a rectangular convex portion, an arc-shaped convex portion and a triangular convex portion; And / or, the shape of the recess includes at least one of a rectangular groove, an arc-shaped groove and a triangular groove.

6. The bulk acoustic wave resonator according to claim 1, characterized in that The top electrode includes at least one second side, and the number of the second sides is greater than or equal to 1 and less than or equal to M-1; The piezoelectric layer is provided with an isolation groove structure, wherein the isolation groove structure is provided on a surface of the piezoelectric layer away from the substrate and / or on a surface of the piezoelectric layer adjacent to the substrate; And / or, the second side is provided with a microstructure for reducing shear wave propagation.

7. The BAW resonator according to claim 6, characterized in that: The microstructure includes at least one of a cantilever structure, a protruding structure, and a concave structure.

8. The bulk acoustic wave resonator according to claim 7, characterized in that: It also includes an insulating filling layer, wherein the insulating filling layer is located in the isolation groove structure, and / or the insulating filling layer is located in a region between the cantilever structure and the piezoelectric layer.

9. The BAW resonator according to claim 1, characterized in that: It also includes a supporting layer, which is located on the surface of the substrate and covers the sound reflection structure; The bottom electrode is arranged on a surface of the support layer away from the substrate.

10. A communication device, characterized in that: A bulk acoustic wave resonator comprising any one of claims 1 to 9; The communication device includes at least one of a filter, a duplexer and a multiplexer.

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