A bulk acoustic wave resonator device, a filtering device and a radio frequency front-end device

Abstract

Embodiments of the present invention provide a bulk acoustic wave resonator device, a filtering device, and a radio frequency front-end device. Among them, the bulk acoustic wave resonator device includes: a first layer, the first layer includes a cavity; a first electrode layer, at least one end of the first electrode layer is located in the cavity; a piezoelectric layer, located on the first electrode layer and covering the cavity, the piezoelectric layer includes a first side and a second side opposite to the first side, and the first electrode layer is located on the first side; a second electrode layer, located on the second side and on the piezoelectric layer; and at least one side cavity, located between the first layer and the piezoelectric layer, embedded in the first layer and communicating with the cavity, and the depth of at least one side cavity is less than the depth of the cavity. By arranging a shallower side cavity beside at least one side of the cavity, transverse acoustic waves will be reflected at the junction of the piezoelectric layer or the electrode layer or the edge structure and the side cavity, thereby blocking the leakage waves propagating towards the support layer (for example, the substrate, the intermediate layer) in the transverse mode and improving the Q value.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology. Specifically, the present invention relates to a bulk acoustic wave resonator, a filtering device, and a radio frequency front-end device. Background Art

[0002] The radio frequency (RF) front-end chip of a wireless communication device includes a power amplifier, an antenna switch, a radio frequency filter, a multiplexer, a low-noise amplifier, etc. Among them, the radio frequency filter includes a piezoelectric surface acoustic wave (SAW) filter, a piezoelectric bulk acoustic wave (BAW) filter, a micro-electro-mechanical system (MEMS) filter, an integrated passive devices (IPD) filter, etc.

[0003] The quality factor value (Q value) of a BAW resonator is relatively high. A radio frequency filter with low insertion loss and high out-of-band rejection made of a BAW resonator, that is, a BAW filter, is the mainstream radio frequency filter used in wireless communication devices such as mobile phones and base stations. Among them, the Q value is the quality factor value of the resonator, defined as the center frequency divided by the 3 dB bandwidth of the resonator. The higher the Q value, the better the performance of the resonator and the better the performance of the filter made. During the vibration of a BAW resonator, mechanical energy is converted into electrical energy, or electrical energy is converted into mechanical energy. The degree of this energy conversion is represented by the electro-mechanical coupling factor ( ).

[0004]

[0005] Among them, f s is the resonance frequency, f p is the anti-resonance frequency. When the resonator is larger, the bandwidth of the filter that can be made by the resonator is larger. The operating frequency of a BAW filter is generally 0.7 GHz to 7 GHz.

[0006] As wireless communication technology evolves step by step, more and more frequency bands are used. At the same time, with the application of technologies such as carrier aggregation for stacked use of frequency bands, the mutual interference between wireless frequency bands has become increasingly serious. High-performance BAW technology can solve the problem of mutual interference between frequency bands. With the advent of the 5G era, wireless mobile networks have introduced higher communication frequency bands and wider frequency bands. Currently, only BAW technology can solve the filtering problem of high-frequency bands and high bandwidths.

[0007] BAW filters are composed of BAW resonators. The BAW resonators convert electrical signals into acoustic signals through metal-piezoelectric film-metal transducers, and then convert the acoustic signals back into electrical signals through metal-piezoelectric film-metal transducers. BAW filters filter signals in the acoustic signal range. Since the speed of acoustic signals is about one hundred-thousandth of the speed of electrical signals at the same frequency, the size of BAW filters at the same frequency is much smaller than that of electrical RF filters. Since the metal-piezoelectric film-metal transducer is the main component of the BAW resonator, whether the acoustic structure of the BAW resonator can effectively limit the leakage of leaky wave energy directly determines the electromechanical coupling coefficient and Q value of the BAW resonator. The 5G mobile communication technology has put forward higher requirements for the passband bandwidth, insertion loss and out-of-band rejection of BAW filters. The above three indicators are related to the electromechanical coupling coefficient and Q value of the BAW resonator. Therefore, the acoustic structure of the BAW resonator needs to be further optimized and improved.

[0008] Figure 1 Fig. 4 shows a BAW filter circuit 100, including a ladder circuit composed of multiple BAW resonators. Among them, f1, f2, f3, and f4 respectively represent four different frequencies. Inside each BAW resonator, alternating positive and negative voltages are generated on the metal electrodes on both sides of the resonator piezoelectric layer. The piezoelectric layer generates acoustic waves through the alternating positive and negative voltages. The acoustic waves in the resonator propagate in a direction perpendicular to the piezoelectric layer. In order to form resonance, the acoustic waves need to be totally reflected on the upper surface of the upper metal electrode and the lower surface of the lower metal electrode to form standing acoustic waves. The condition for acoustic wave reflection is that there is a large difference in acoustic impedance between the contact area of the upper surface of the upper metal electrode and the lower surface of the lower metal electrode and the acoustic impedance of the metal electrode.

[0009] A Film Bulk Acoustic wave Resonator (FBAR) is a BAW resonator that can confine acoustic wave energy within the device. There is air or vacuum above the resonance region of the resonator, and there is a cavity below. The acoustic impedance of air and vacuum is quite different from that of the metal electrode, and acoustic waves can be totally reflected on the upper surface of the upper metal electrode and the lower surface of the lower metal electrode to form standing waves.

[0010] Figure 2The figure shows a schematic cross-sectional structure diagram of an FBAR 200. The FBAR 200 includes: a substrate 201, the upper surface side of the substrate 201 includes a cavity 203; an electrode layer 205, located on the substrate 201 and the cavity 203; a piezoelectric layer 207, located on the substrate 201, covering the electrode layer 205, the piezoelectric layer 207 includes a protrusion 207a, located above the electrode layer 205; an electrode layer 209, located on the piezoelectric layer 207, the electrode layer 209 includes a protrusion 209a, located on the protrusion 207a; wherein, a resonance region 211 (i.e., the overlapping region of the electrode layer 205 and the protrusion 209a) is located on the cavity 203, and has an overlapping contact portion with the substrate 201. If the acoustic impedance of the substrate 201 is similar to the acoustic impedance of the piezoelectric layer 207, the lateral acoustic wave generated in the resonance region 211 will diffuse towards the non-resonance region in the direction of the arrow and propagate into the substrate 201, thereby causing a decrease in the Q value of the resonator. Summary of the Invention

[0011] The problem solved by the present invention is to provide a bulk acoustic wave resonator device that can block the leakage wave propagating towards the support layer (for example, the substrate, the intermediate layer) in the lateral mode, thereby improving the Q value.

[0012] To solve the above problems, an embodiment of the present invention provides a bulk acoustic wave resonator device, including: a first layer, the first layer includes a cavity; a first electrode layer, at least one end of the first electrode layer is located in the cavity; a piezoelectric layer, located vertically on the first electrode layer, covering the cavity, the piezoelectric layer includes a first side and a second side opposite to the first side along the vertical direction, the first electrode layer is located on the first side, and the overlapping region of the first electrode layer, the second electrode layer and the piezoelectric layer is a first region; a second electrode layer, located on the second side, vertically located on the piezoelectric layer; and at least one side cavity, located between the first layer and the piezoelectric layer, embedded in the first layer, communicating with the cavity, the depth of the at least one side cavity is less than the depth of the cavity, and the at least one side cavity is located horizontally outside the first region.

[0013] It should be noted that, beside at least one side of the cavity, a relatively shallow side cavity is provided outside the resonance region. The acoustic impedance of the vacuum or air in the side cavity does not match the acoustic impedance of the piezoelectric layer or the electrode layer or the edge structure (i.e., the acoustic impedances are different), and the lateral acoustic wave will be reflected at the junction of the piezoelectric layer or the electrode layer or the edge structure and the side cavity, thereby blocking the leakage wave propagating towards the support layer (for example, the substrate, the intermediate layer) in the lateral mode and improving the Q value.

[0014] In some embodiments, the at least one side cavity includes: a first side cavity, which is located outside the first region along the horizontal direction, contacts the piezoelectric layer, and has an overlapping portion with the second electrode layer.

[0015] In some embodiments, the at least one side cavity includes: a second side cavity, which is located outside the first region along the horizontal direction, is located between the first layer and the first electrode layer, contacts the first electrode layer, and has an overlapping portion with the first electrode layer.

[0016] In some embodiments, the bulk acoustic wave resonator device further includes: at least one edge structure, which is located at the edge of the overlapping portion of the first electrode layer and the second electrode layer.

[0017] In some embodiments, the at least one edge structure includes: a first edge structure, which is located on the second side and on the second electrode layer, wherein the first edge structure includes a first surrounding portion, and the first surrounding portion is located on the edge of the overlapping portion of the second electrode layer and the first electrode layer.

[0018] In some embodiments, the first surrounding portion is annular.

[0019] In some embodiments, the material of the first edge structure includes metal.

[0020] In some embodiments, the at least one edge structure includes: a second edge structure, with the first electrode layer located on the second edge structure, wherein the second edge structure includes a second surrounding portion, and the second surrounding portion is located inside the cavity and on the edge of the overlapping portion of the first electrode layer and the second electrode layer.

[0021] In some embodiments, the second surrounding portion is annular.

[0022] In some embodiments, the material of the second edge structure includes metal.

[0023] In some embodiments, the at least one side cavity includes: a third side cavity, which is located outside the first region along the horizontal direction, is located between the first layer and the second edge structure, contacts the second edge structure, and has an overlapping portion with the second edge structure.

[0024] In some embodiments, the at least one edge structure includes: a third edge structure, which is located on the second side and on the second electrode layer, wherein the third edge structure includes a third surrounding portion, and the third surrounding portion is located on a partial edge of the overlapping portion of the second electrode layer and the first electrode layer.

[0025] In some embodiments, the at least one edge structure further includes: a fourth edge structure, on which the first electrode layer is located, wherein the fourth edge structure includes a fourth surrounding portion located within the cavity and at a partial edge of the overlapping portion of the first electrode layer and the second electrode layer.

[0026] In some embodiments, the third surrounding portion and the fourth surrounding portion partially overlap to form an annular surrounding edge.

[0027] In some embodiments, the material of the third edge structure includes metal, and the material of the fourth edge structure includes metal.

[0028] In some embodiments, the at least one side cavity includes: a fourth side cavity located outside the first region along the horizontal direction, between the first layer and the fourth edge structure, in contact with the fourth edge structure, and having an overlapping portion with the fourth edge structure.

[0029] In some embodiments, the at least one edge structure includes: a fifth edge structure located on the second side and on the piezoelectric layer, the fifth edge structure includes a fifth surrounding portion, the second electrode layer is located inside the fifth surrounding portion, and the fifth surrounding portion overlaps with the first electrode layer, wherein the overlapping portion of the second electrode layer and the first electrode layer is the second electrode layer.

[0030] In some embodiments, the fifth surrounding portion is annular.

[0031] In some embodiments, the material of the fifth edge structure includes metal.

[0032] In some embodiments, the at least one side cavity includes: a fifth side cavity located outside the first region along the horizontal direction, in contact with the piezoelectric layer, and having an overlapping portion with the fifth edge structure.

[0033] In some embodiments, the at least one edge structure includes a sixth edge structure located on the first side, and the piezoelectric layer is also located on the sixth edge structure. The sixth edge structure includes a sixth surrounding portion located within the cavity, the first electrode layer is located inside the sixth surrounding portion, and the sixth surrounding portion overlaps with the second electrode layer, wherein the overlapping portion of the first electrode layer and the second electrode layer is the first electrode layer.

[0034] In some embodiments, the sixth surrounding portion is annular.

[0035] In some embodiments, the material of the sixth edge structure includes metal.

[0036] In some embodiments, the at least one side cavity includes: a sixth side cavity, which is located outside the first region along the horizontal direction, between the first layer and the sixth edge structure, in contact with the sixth edge structure, and has an overlapping portion with the sixth edge structure.

[0037] In some embodiments, the at least one edge structure includes a seventh edge structure, which is located on the second side and on the piezoelectric layer. The seventh edge structure includes a seventh surrounding portion, and the seventh surrounding portion is located at a partial edge of the overlapping portion of the second electrode layer and the first electrode layer.

[0038] In some embodiments, the at least one side cavity includes: a seventh side cavity, which is located outside the first region along the horizontal direction, in contact with the piezoelectric layer, and has an overlapping portion with the seventh edge structure.

[0039] In some embodiments, the at least one edge structure further includes an eighth edge structure, which is located on the first side, and the piezoelectric layer is also located on the eighth edge structure. The eighth edge structure includes an eighth surrounding portion, and the eighth surrounding portion is located inside the cavity and at a partial edge of the overlapping portion of the first electrode layer and the second electrode layer.

[0040] In some embodiments, the eighth surrounding portion and the seventh surrounding portion partially overlap to form an annular surrounding edge.

[0041] In some embodiments, the material of the seventh edge structure includes metal, and the material of the eighth edge structure includes metal.

[0042] In some embodiments, the at least one side cavity includes: an eighth side cavity, which is located outside the first region along the horizontal direction, between the first layer and the eighth edge structure, in contact with the eighth edge structure, and has an overlapping portion with the eighth edge structure.

[0043] In some embodiments, the first layer includes: an intermediate layer, and the intermediate layer includes the cavity. Wherein, the material of the intermediate layer includes but is not limited to at least one of the following: polymer, insulating dielectric, polysilicon.

[0044] In some embodiments, the at least one side cavity is located between the intermediate layer and the piezoelectric layer and is embedded in the intermediate layer.

[0045] An embodiment of the present invention further provides a filtering device, including but not limited to: at least one bulk acoustic wave resonator device provided in one of the above embodiments.

[0046] An embodiment of the present invention further provides a radio frequency front-end device, including but not limited to: a power amplification device and at least one filtering device provided in the above embodiments; the power amplification device is connected to the filtering device.

[0047] An embodiment of the present invention further provides a radio frequency front-end device, including but not limited to: a low-noise amplification device and at least one filtering device provided in the above embodiments; the low-noise amplification device is connected to the filtering device.

[0048] An embodiment of the present invention further provides a radio frequency front-end device, including but not limited to: a multiplexing device, and the multiplexing device includes at least one filtering device provided in the above embodiments. Description of the Drawings

[0049] Figure 1 is a schematic structural diagram of a BAW filter circuit 100;

[0050] Figure 2 is a schematic cross-sectional A structure diagram of an FBAR 200;

[0051] Figure 3a is a schematic cross-sectional A structure diagram of a bulk acoustic wave resonator device 300 according to an embodiment of the present invention;

[0052] Figure 3b is a schematic structural diagram of a hexagonal crystal grain;

[0053] Figure 3c (i) is a schematic structural diagram of an orthorhombic crystal grain;

[0054] Figure 3c (ii) is a schematic structural diagram of a tetragonal crystal grain;

[0055] Figure 3c (iii) is a schematic structural diagram of a cubic crystal grain;

[0056] Figure 3d is a performance schematic diagram of a bulk acoustic wave resonator device 300 according to an embodiment of the present invention;

[0057] Figure 3e is a top view structural schematic diagram of a bulk acoustic wave resonator device 300 according to an embodiment of the present invention;

[0058] Figure 4a is a schematic cross-sectional A structure diagram of a bulk acoustic wave resonator device 400 according to an embodiment of the present invention;

[0059] Figure 4b is a top view structural schematic diagram of a bulk acoustic wave resonator device 400 according to an embodiment of the present invention;

[0060] Figure 5aIt is a schematic cross-sectional view of Structure A of a bulk acoustic wave resonator 500 according to an embodiment of the present invention;

[0061] Figure 5b It is a schematic top view of a bulk acoustic wave resonator 500 according to an embodiment of the present invention;

[0062] Figure 6a It is a schematic cross-sectional view of Structure A of a bulk acoustic wave resonator 600 according to an embodiment of the present invention;

[0063] Figure 6b It is a schematic top view of a bulk acoustic wave resonator 600 according to an embodiment of the present invention;

[0064] Figure 6c It is a schematic cross-sectional view of Structure B of a bulk acoustic wave resonator 600 according to an embodiment of the present invention;

[0065] Figure 7a It is a schematic cross-sectional view of Structure A of a bulk acoustic wave resonator 700 according to an embodiment of the present invention;

[0066] Figure 7b It is a schematic top view of a bulk acoustic wave resonator 700 according to an embodiment of the present invention;

[0067] Figure 8 It is a schematic cross-sectional view of Structure A of a bulk acoustic wave resonator 800 according to an embodiment of the present invention;

[0068] Figure 9 It is a schematic cross-sectional view of Structure A of a bulk acoustic wave resonator 900 according to an embodiment of the present invention;

[0069] Figure 10a It is a schematic cross-sectional view of Structure A of a bulk acoustic wave resonator 1000 according to an embodiment of the present invention;

[0070] Figure 10b It is a schematic top view of a bulk acoustic wave resonator 1000 according to an embodiment of the present invention;

[0071] Figure 10c It is a schematic cross-sectional view of Structure B of a bulk acoustic wave resonator 1000 according to an embodiment of the present invention;

[0072] Figure 11 It is a schematic cross-sectional view of Structure A of a bulk acoustic wave resonator 1100 according to an embodiment of the present invention. Detailed implementation manners

[0073] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following will describe the detailed implementation manners of the present invention in conjunction with the accompanying drawings.

[0074] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, the present invention may be practiced in other ways than those specifically described herein, and thus the present invention is not limited by the specific embodiments disclosed below.

[0075] As described in the background art section, if the acoustic impedance of the substrate is similar to that of the piezoelectric layer, the lateral acoustic waves generated in the resonance region will diffuse into the non-resonance region in the direction of the arrow and propagate into the substrate, thereby reducing the Q value of the resonator.

[0076] The inventors of the present invention have found that a relatively shallow side cavity is provided outside the resonance region beside at least one side of the cavity. The acoustic impedance of the vacuum or air in the side cavity does not match (i.e., is different) the acoustic impedance of the piezoelectric layer, the electrode layer, or the edge structure. The lateral acoustic waves will be reflected at the junction of the piezoelectric layer, the electrode layer, or the edge structure and the side cavity, thereby blocking the leakage waves propagating towards the support layer (e.g., the substrate, the intermediate layer) in the lateral mode and increasing the Q value.

[0077] An embodiment of the present invention provides a bulk acoustic wave resonator device, including: a first layer, the first layer including a cavity; a first electrode layer, at least one end of the first electrode layer being located in the cavity; a piezoelectric layer, located on the first electrode layer in a vertical direction and covering the cavity. The piezoelectric layer includes a first side and a second side opposite to the first side in the vertical direction, and the first electrode layer is located on the first side; a second electrode layer, located on the second side in the vertical direction and on the piezoelectric layer. The overlapping region of the first electrode layer, the second electrode layer, and the piezoelectric layer is a first region; and at least one side cavity, located between the first layer and the piezoelectric layer, embedded in the first layer and communicating with the cavity. The depth of the at least one side cavity is less than the depth of the cavity, and the at least one side cavity is located outside the first region in the horizontal direction (i.e., has no overlapping portion with the first region).

[0078] It should be noted that a relatively shallow side cavity is provided outside the resonance region beside at least one side of the cavity. The acoustic impedance of the vacuum or air in the side cavity does not match (i.e., is different) the acoustic impedance of the piezoelectric layer, the electrode layer, or the edge structure. The lateral acoustic waves will be reflected at the junction of the piezoelectric layer, the electrode layer, or the edge structure and the side cavity, thereby blocking the leakage waves propagating towards the support layer (e.g., the substrate, the intermediate layer) in the lateral mode and increasing the Q value.

[0079] In some embodiments, the at least one side cavity includes: a first side cavity, located outside the first region in the horizontal direction, contacting the piezoelectric layer, and having an overlapping portion with the second electrode layer.

[0080] In some embodiments, the at least one side cavity includes: a second side cavity, which is located outside the first region along the horizontal direction, between the first layer and the first electrode layer, contacts the first electrode layer, and has an overlapping portion with the first electrode layer.

[0081] In some embodiments, the bulk acoustic wave resonator device further includes: at least one edge structure, which is located at the edge of the overlapping portion of the first electrode layer and the second electrode layer.

[0082] In some embodiments, the at least one edge structure includes: a first edge structure, which is located on the second side and on the second electrode layer. Wherein, the first edge structure includes a first surrounding portion, and the first surrounding portion is located on the edge of the overlapping portion of the second electrode layer and the first electrode layer. In some embodiments, the first surrounding portion is annular. In some embodiments, the material of the first edge structure includes metal.

[0083] In some embodiments, the at least one edge structure includes: a second edge structure, with the first electrode layer located on the second edge structure. Wherein, the second edge structure includes a second surrounding portion, and the second surrounding portion is located inside the cavity and on the edge of the overlapping portion of the first electrode layer and the second electrode layer. In some embodiments, the second surrounding portion is annular. In some embodiments, the material of the second edge structure includes metal. In some embodiments, the at least one side cavity includes: a third side cavity, which is located outside the first region along the horizontal direction, between the first layer and the second edge structure, contacts the second edge structure, and has an overlapping portion with the second edge structure.

[0084] In some embodiments, the at least one edge structure includes: a third edge structure, which is located on the second side and on the second electrode layer. Wherein, the third edge structure includes a third surrounding portion, and the third surrounding portion is located on a partial edge of the overlapping portion of the second electrode layer and the first electrode layer. In some embodiments, the at least one edge structure further includes: a fourth edge structure, with the first electrode layer located on the fourth edge structure. Wherein, the fourth edge structure includes a fourth surrounding portion, and the fourth surrounding portion is located inside the cavity and on a partial edge of the overlapping portion of the first electrode layer and the second electrode layer. In some embodiments, the third surrounding portion and the fourth surrounding portion partially overlap to form an annular surrounding edge. In some embodiments, the material of the third edge structure includes metal, and the material of the fourth edge structure includes metal. In some embodiments, the at least one side cavity includes: a fourth side cavity, which is located outside the first region along the horizontal direction, between the first layer and the fourth edge structure, contacts the fourth edge structure, and has an overlapping portion with the fourth edge structure.

[0085] In some embodiments, the at least one edge structure includes: a fifth edge structure located on the second side and on the piezoelectric layer. The fifth edge structure includes a fifth surrounding portion, and the second electrode layer is located inside the fifth surrounding portion. The fifth surrounding portion coincides with the first electrode layer, where the overlapping portion of the second electrode layer and the first electrode layer is the second electrode layer. In some embodiments, the fifth surrounding portion is annular. In some embodiments, the material of the fifth edge structure includes metal. In some embodiments, the at least one side cavity includes: a fifth side cavity located outside the first region along the horizontal direction, contacting the piezoelectric layer, and having an overlapping portion with the fifth edge structure.

[0086] In some embodiments, the at least one edge structure includes a sixth edge structure located on the first side, and the piezoelectric layer is also located on the sixth edge structure. The sixth edge structure includes a sixth surrounding portion, and the sixth surrounding portion is located inside the cavity. The first electrode layer is located inside the sixth surrounding portion. The sixth surrounding portion coincides with the second electrode layer, where the overlapping portion of the first electrode layer and the second electrode layer is the first electrode layer. In some embodiments, the sixth surrounding portion is annular. In some embodiments, the material of the sixth edge structure includes metal. In some embodiments, the at least one side cavity includes: a sixth side cavity located outside the first region along the horizontal direction, located between the first layer and the sixth edge structure, contacting the sixth edge structure, and having an overlapping portion with the sixth edge structure.

[0087] In some embodiments, the at least one edge structure includes a seventh edge structure located on the second side and on the piezoelectric layer. The seventh edge structure includes a seventh surrounding portion located at a partial edge of the overlapping portion of the second electrode layer and the first electrode layer. In some embodiments, the at least one side cavity includes: a seventh side cavity located outside the first region along the horizontal direction, contacting the piezoelectric layer, and having an overlapping portion with the seventh edge structure. In some embodiments, the at least one edge structure further includes an eighth edge structure located on the first side, with the piezoelectric layer also located on the eighth edge structure. The eighth edge structure includes an eighth surrounding portion located within the cavity and at a partial edge of the overlapping portion of the first electrode layer and the second electrode layer. In some embodiments, the eighth surrounding portion and the seventh surrounding portion partially overlap to form an annular surrounding edge. In some embodiments, the material of the seventh edge structure includes metal, and the material of the eighth edge structure includes metal. In some embodiments, the at least one side cavity includes: an eighth side cavity located outside the first region along the horizontal direction, located between the first layer and the eighth edge structure, contacting the eighth edge structure, and having an overlapping portion with the eighth edge structure.

[0088] In some embodiments, the first layer includes: an intermediate layer, and the intermediate layer includes the cavity. Wherein, the material of the intermediate layer includes, but is not limited to, at least one of the following: polymer, insulating dielectric, polysilicon. In some embodiments, the at least one side cavity is located between the intermediate layer and the piezoelectric layer and is embedded in the intermediate layer.

[0089] An embodiment of the present invention further provides a filtering device, including, but not limited to: at least one bulk acoustic wave resonator device provided in one of the above embodiments.

[0090] An embodiment of the present invention further provides a radio frequency front-end device, including, but not limited to: a power amplification device and at least one filtering device provided in the above embodiments; the power amplification device is connected to the filtering device.

[0091] An embodiment of the present invention further provides a radio frequency front-end device, including, but not limited to: a low-noise amplification device and at least one filtering device provided in the above embodiments; the low-noise amplification device is connected to the filtering device.

[0092] An embodiment of the present invention further provides a radio frequency front-end device, including, but not limited to: a multiplexing device, and the multiplexing device includes at least one filtering device provided in the above embodiments.

[0093] Figure 3 to Figure 11Multiple specific embodiments of the present invention are shown. The multiple specific embodiments adopt resonance devices with different structures. However, the present invention can also be implemented in other ways different from those described herein. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0094] Figure 3a It is a schematic cross-sectional view of Structure A of a bulk acoustic wave resonator device 300 according to an embodiment of the present invention.

[0095] As Figure 3a shown, an embodiment of the present invention provides a bulk acoustic wave resonator device 300, including: a substrate 301; an intermediate layer 302 located on the substrate 301. The upper surface side of the intermediate layer 302 includes a cavity 303 and a groove 304. Among them, the groove 304 is located on one side of the cavity 303 and communicates with the cavity 303. The depth of the groove 304 is less than the depth of the cavity 303; an electrode layer 305, the first end 305a of the electrode layer 305 is located in the cavity 303, and the second end 305b of the electrode layer 305 is located in the groove 304. Among them, the depth of the groove 304 is equal to the thickness of the electrode layer 305; a piezoelectric layer 306 located on the electrode layer 305 and the intermediate layer 302, covering the cavity 303. Among them, the piezoelectric layer 306 includes a first side 306a and a second side 306b opposite to the first side 306a. The electrode layer 305 and the intermediate layer 302 are located on the first side 306a; an electrode layer 307 located on the second side 306b and on the piezoelectric layer 306; a side cavity 308 located on the first side 306a, between the intermediate layer 302 and the piezoelectric layer 306, embedded in the intermediate layer 302 and communicating with the cavity 303. The side cavity 308 contacts the piezoelectric layer 306; and a side cavity 309 located between the intermediate layer 302 and the electrode layer 305, embedded in the intermediate layer 302 and communicating with the cavity 303; wherein, the depth of the side cavity 308 is less than the depth of the cavity 303, and the depth of the side cavity 309 is less than the depth of the cavity 303.

[0096] In this embodiment, the overlapping region of the electrode layer 305, the piezoelectric layer 306, and the electrode layer 307 is the resonance region, and the side cavity 308 and the side cavity 309 are located outside the resonance region in the horizontal direction.

[0097] In this embodiment, the material of the substrate 301 includes but is not limited to at least one of the following: silicon, silicon carbide, glass, gallium arsenide, gallium nitride, and ceramic.

[0098] In this embodiment, the material of the intermediate layer 302 includes, but is not limited to, at least one of the following: polymer, insulating dielectric, polysilicon. In this embodiment, the polymer includes, but is not limited to, at least one of the following: benzocyclobutene (i.e., BCB), photosensitive epoxy resin photoresist (e.g., SU-8), polyimide. In this embodiment, the insulating dielectric includes, but is not limited to, at least one of the following: aluminum nitride, silicon dioxide, silicon nitride, titanium oxide.

[0099] In this embodiment, the material of the electrode layer 305 includes, but is not limited to, at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, beryllium.

[0100] In this embodiment, the piezoelectric layer 306 is a flat layer and also covers the upper surface side of the intermediate layer 302. In this embodiment, the material of the piezoelectric layer 306 includes, but is not limited to, at least one of the following: aluminum nitride, aluminum nitride alloy, gallium nitride, zinc oxide, lithium tantalate, lithium niobate, lead zirconate titanate, lead magnesium niobate-titanate.

[0101] In this embodiment, the piezoelectric layer 306 includes a plurality of grains, and the plurality of grains includes a first grain and a second grain. Among them, the first grain and the second grain are any two grains in the plurality of grains. Those skilled in the art know that the crystal orientation, crystal plane, etc. of the grains can be represented based on a coordinate system. As Figure 3b shown, for grains of the hexagonal crystal system, such as aluminum nitride grains, an ac three-dimensional coordinate system (including the a-axis and the c-axis) is used for representation. As Figure 3c shown, for grains of (i) the orthorhombic crystal system (a≠b≠c), (ii) the tetragonal crystal system (a = b≠c), (iii) the cubic crystal system (a = b = c), etc., an xyz three-dimensional coordinate system (including the x-axis, the y-axis, and the z-axis) is used for representation. In addition to the above two examples, the grains can also be represented based on other coordinate systems known to those skilled in the art. Therefore, the present invention is not limited by the above two examples.

[0102] In this embodiment, the first grain can be represented based on a first three-dimensional coordinate system, and the second grain can be represented based on a second three-dimensional coordinate system. Among them, the first three-dimensional coordinate system includes at least a first coordinate axis along a first direction and a third coordinate axis along a third direction, and the second three-dimensional coordinate system includes at least a second coordinate axis along a second direction and a fourth coordinate axis along a fourth direction. Among them, the first coordinate axis corresponds to the height of the first grain, and the second coordinate axis corresponds to the height of the second grain.

[0103] In this embodiment, the first direction and the second direction are the same or opposite. It should be noted that the first direction and the second direction being the same means that the included angle range between the vector along the first direction and the vector along the second direction includes 0 degrees to 5 degrees; the first direction and the second direction being opposite means that the included angle range between the vector along the first direction and the vector along the second direction includes 175 degrees to 180 degrees.

[0104] In another embodiment, the first three-dimensional coordinate system is an ac three-dimensional coordinate system, where the first coordinate axis is the first c-axis, and the third coordinate axis is the first a-axis; the second three-dimensional coordinate system is an ac three-dimensional coordinate system, the second coordinate axis is the second c-axis, and the fourth coordinate axis is the second a-axis, where the first c-axis and the second c-axis point in the same or opposite directions.

[0105] In another embodiment, the first three-dimensional coordinate system further includes a fifth coordinate axis along a fifth direction, and the second three-dimensional coordinate system further includes a sixth coordinate axis along a sixth direction. In another embodiment, the first direction and the second direction are the same or opposite, and the third direction and the fourth direction are the same or opposite. It should be noted that the third direction and the fourth direction being the same means that the included angle range between the vector along the third direction and the vector along the fourth direction includes 0 degrees to 5 degrees; the third direction and the fourth direction being opposite means that the included angle range between the vector along the third direction and the vector along the fourth direction includes 175 degrees to 180 degrees.

[0106] In another embodiment, the first three-dimensional coordinate system is an xyz three-dimensional coordinate system, where the first coordinate axis is the first z-axis, the third coordinate axis is the first y-axis, and the fifth coordinate axis is the first x-axis; the second three-dimensional coordinate system is an xyz three-dimensional coordinate system, the second coordinate axis is the second z-axis, the fourth coordinate axis is the second y-axis, and the sixth coordinate axis is the second x-axis. In another embodiment, the first z-axis and the second z-axis point in the same direction, and the first y-axis and the second y-axis point in the same direction. In another embodiment, the first z-axis and the second z-axis point in opposite directions, and the first y-axis and the second y-axis point in opposite directions. In another embodiment, the first z-axis and the second z-axis point in the same direction, and the first y-axis and the second y-axis point in opposite directions. In another embodiment, the first z-axis and the second z-axis point in opposite directions, and the first y-axis and the second y-axis point in the same direction.

[0107] In this embodiment, the piezoelectric layer 306 includes a plurality of crystal grains, and the full width at half maximum (FWHM) of the rocking curve of the crystal formed by the plurality of crystal grains is less than 2.5 degrees. It should be noted that the rocking curve describes the angular divergence of a specific crystal plane (the crystal plane with a determined diffraction angle) in the sample, which is represented by a planar coordinate system. Among them, the abscissa is the angle between the crystal plane and the sample surface, and the ordinate represents the diffraction intensity of the crystal plane at a certain angle. The rocking curve is used to represent the crystal quality, and the smaller the FWHM angle, the better the crystal quality. In addition, the full width at half maximum (FWHM) refers to the distance between two points with function values equal to half of the peak value in a peak of the function.

[0108] It should be noted that forming the piezoelectric layer 306 on the plane can make the piezoelectric layer 306 not include crystal grains with obvious turning, thereby improving the electromechanical coupling coefficient of the resonant device and the Q value of the resonant device.

[0109] In this embodiment, the material of the electrode layer 307 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, and beryllium.

[0110] In this embodiment, the part of the electrode layer 305 that coincides with the electrode layer 307 is located in the cavity 303; the part of the electrode 307 that coincides with the electrode layer 305 is located above the cavity 303.

[0111] In this embodiment, the cavity 303 is located inside the side cavity 308 (that is, on the side pointing to the central axis of the filtering device 300), and the cavity 303 is also located inside the side cavity 309. In this embodiment, the electrode layer 307 is located above the side cavity 308 and has an overlapping part with the side cavity 308; the electrode layer 305 is located on the side cavity 309 and has an overlapping part with the side cavity 309.

[0112] It should be noted that the acoustic impedance of the vacuum state or air in the side cavity 308 is less than the acoustic impedance of the piezoelectric layer 306, and the acoustic impedance of the vacuum state or air in the side cavity 309 is less than the acoustic impedance of the electrode layer 305. The acoustic wave in the transverse mode is reflected at the junction of the side cavity 308 and the piezoelectric layer 306 and at the junction of the side cavity 309 and the electrode layer 305, thereby blocking the leakage wave propagating towards the intermediate layer 302 in the transverse mode and improving the Q value. For a more intuitive understanding of this beneficial effect, please refer to Figure 3d , the quality factor curve 310 represents the normalized Q value of the BAW resonant device without side cavities, and the quality factor curve 311 represents the normalized Q value of the BAW resonant device including side cavities (for example, the side cavity 308 or the side cavity 309). It should be noted thatFigure 3d It is only schematic and is used to more intuitively understand the beneficial effects of the embodiments of the present invention, but it is not equivalent to the actual performance of the BAW resonator device of the embodiments of the present invention.

[0113] Figure 3e It is a top view structural schematic diagram of a bulk acoustic wave resonator device 300 according to an embodiment of the present invention.

[0114] As Figure 3e shown, in this embodiment, the cavity 303 is octagonal, corresponding to the shape of the overlapping portion of the electrode layer 305 and the electrode layer 307. It should be noted that cavities of other shapes known to those skilled in the art, such as hexagons, pentagons, etc., can also be applied to the embodiments of the present invention. In this embodiment, the side cavity 308 is adjacent to the first side of the cavity 303, and the side cavity 309 is adjacent to the second side of the cavity 303.

[0115] Figure 4a It is a cross-sectional view A structural schematic diagram of a bulk acoustic wave resonator device 400 according to an embodiment of the present invention.

[0116] As Figure 4a shown, an embodiment of the present invention provides a bulk acoustic wave resonator device 400 including: a substrate 401; an intermediate layer 402 located on the substrate 401, the upper surface side of the intermediate layer 402 including a cavity 403 and a groove 404, wherein the groove 404 is located on one side of the cavity 403 and communicates with the cavity 403, and the depth of the groove 404 is less than the depth of the cavity 403; an electrode layer 405, a first end 405a of the electrode layer 405 is located in the cavity 403, and a second end 405b of the electrode layer 405 is located in the groove 404, wherein the depth of the groove 404 is equal to the thickness of the electrode layer 405; a piezoelectric layer 406 located on the electrode layer 405 and the intermediate layer 402, covering the cavity 403, wherein the piezoelectric layer 406 includes a first side 406a and a second side 406b opposite to the first side 406a, and the electrode layer 405 and the intermediate layer 402 are located on the first side 406a; an electrode layer 407 located on the second side 406b and on the piezoelectric layer 406; an edge structure 408 located on the second side 406b and on the electrode layer 407, the piezoelectric layer 406 and the edge structure 408 are respectively located on both sides of the electrode layer 407, wherein the edge structure 408 includes a surrounding portion 408a located on the edge of the overlapping portion of the electrode layer 407 and the electrode layer 405; and a side cavity 409 located between the intermediate layer 402 and the electrode layer 405, embedded in the intermediate layer 402, and communicating with the cavity 403; wherein the depth of the side cavity 409 is less than the depth of the cavity 403.

[0117] As can be seen from Figure 4a the resonance region 410 (i.e., the overlapping region of the electrode layer 405 and the electrode layer 407) is suspended relative to the cavity 403 and has no overlapping portion with the intermediate layer 402, thereby blocking the leakage of acoustic waves at the horizontal edges of the resonance region 410 in the lateral mode into the intermediate layer 402, and the Q value can be improved.

[0118] In this embodiment, the side cavity 409 is located outside the resonance region 410 in the horizontal direction.

[0119] In this embodiment, the material of the substrate 401 includes but is not limited to at least one of the following: silicon, silicon carbide, glass, gallium arsenide, gallium nitride, ceramics.

[0120] In this embodiment, the material of the intermediate layer 402 includes but is not limited to at least one of the following: polymer, insulating dielectric, polysilicon. In this embodiment, the polymer includes but is not limited to at least one of the following: benzocyclobutene (i.e., BCB), photosensitive epoxy resin photoresist (e.g., SU-8), polyimide. In this embodiment, the insulating dielectric includes but is not limited to at least one of the following: aluminum nitride, silicon dioxide, silicon nitride, titanium oxide.

[0121] In this embodiment, the material of the electrode layer 405 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, beryllium.

[0122] In this embodiment, the piezoelectric layer 406 is a flat layer and also covers the upper surface side of the intermediate layer 402. In this embodiment, the material of the piezoelectric layer 406 includes but is not limited to at least one of the following: aluminum nitride, aluminum nitride alloy, gallium nitride, zinc oxide, lithium tantalate, lithium niobate, lead zirconate titanate, lead magnesium niobate-lead titanate.

[0123] In this embodiment, the piezoelectric layer 406 includes a plurality of grains, and the plurality of grains include a first grain and a second grain, where the first grain and the second grain are any two grains among the plurality of grains. Those skilled in the art know that the crystal orientation, crystal plane, etc. of the grains can be represented based on a coordinate system.

[0124] In this embodiment, the first grain can be represented based on a first three-dimensional coordinate system, and the second grain can be represented based on a second three-dimensional coordinate system, where the first three-dimensional coordinate system at least includes a first coordinate axis along a first direction and a third coordinate axis along a third direction, and the second three-dimensional coordinate system at least includes a second coordinate axis along a second direction and a fourth coordinate axis along a fourth direction, where the first coordinate axis corresponds to the height of the first grain, and the second coordinate axis corresponds to the height of the second grain.

[0125] In this embodiment, the first direction and the second direction are the same or opposite. It should be noted that the first direction and the second direction being the same means that the included angle range between the vector along the first direction and the vector along the second direction includes 0 degrees to 5 degrees; the first direction and the second direction being opposite means that the included angle range between the vector along the first direction and the vector along the second direction includes 175 degrees to 180 degrees.

[0126] In another embodiment, the first three-dimensional coordinate system is an ac three-dimensional coordinate system, where the first coordinate axis is the first c-axis, and the third coordinate axis is the first a-axis; the second three-dimensional coordinate system is an ac three-dimensional coordinate system, the second coordinate axis is the second c-axis, and the fourth coordinate axis is the second a-axis, where the directions of the first c-axis and the second c-axis are the same or opposite.

[0127] In another embodiment, the first three-dimensional coordinate system further includes a fifth coordinate axis along a fifth direction, and the second three-dimensional coordinate system further includes a sixth coordinate axis along a sixth direction. In another embodiment, the first direction and the second direction are the same or opposite, and the third direction and the fourth direction are the same or opposite. It should be noted that the third direction and the fourth direction being the same means that the included angle range between the vector along the third direction and the vector along the fourth direction includes 0 degrees to 5 degrees; the third direction and the fourth direction being opposite means that the included angle range between the vector along the third direction and the vector along the fourth direction includes 175 degrees to 180 degrees.

[0128] In another embodiment, the first three-dimensional coordinate system is an xyz three-dimensional coordinate system, where the first coordinate axis is the first z-axis, the third coordinate axis is the first y-axis, and the fifth coordinate axis is the first x-axis; the second three-dimensional coordinate system is an xyz three-dimensional coordinate system, the second coordinate axis is the second z-axis, the fourth coordinate axis is the second y-axis, and the sixth coordinate axis is the second x-axis. In another embodiment, the directions of the first z-axis and the second z-axis are the same, and the directions of the first y-axis and the second y-axis are the same. In another embodiment, the directions of the first z-axis and the second z-axis are opposite, and the directions of the first y-axis and the second y-axis are opposite. In another embodiment, the directions of the first z-axis and the second z-axis are the same, and the directions of the first y-axis and the second y-axis are opposite. In another embodiment, the directions of the first z-axis and the second z-axis are opposite, and the directions of the first y-axis and the second y-axis are the same.

[0129] In this embodiment, the piezoelectric layer 406 includes a plurality of grains, and the full width at half maximum of the rocking curve of the crystal formed by the plurality of grains is less than 2.5 degrees.

[0130] It should be noted that forming the piezoelectric layer 406 on a plane can make the piezoelectric layer 406 not include significantly turned crystal grains, thereby improving the electromechanical coupling coefficient of the resonant device and the Q value of the resonant device.

[0131] In this embodiment, the material of the electrode layer 407 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, and beryllium.

[0132] In this embodiment, the portion of the electrode layer 405 that coincides with the electrode layer 407 is located within the cavity 403; the portion of the electrode 407 that coincides with the electrode 405 is located above the cavity 403.

[0133] In this embodiment, the material of the edge structure 408 includes metal. In this embodiment, the material of the edge structure 408 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, and beryllium. In this embodiment, the material of the edge structure 408 is the same as the material of the electrode layer 407. In another embodiment, the material of the edge structure above the piezoelectric layer and the material of the upper electrode layer can be different.

[0134] In this embodiment, the surrounding portion 408a is located within the resonant region 410 and serves as the border of the resonant region 410. It should be noted that the acoustic impedance of the edge portion 411 within the resonant region 410 is greater than the acoustic impedance of the middle portion 412 within the resonant region 410, and the acoustic impedance of the edge portion 411 is greater than the acoustic impedance of the non-resonant region, so that the acoustic wave of the transverse mode is reflected at the horizontal edge of the resonant region 410 and remains within the resonant region 410, which can improve the Q value.

[0135] In this embodiment, the inner side of the surrounding portion 408a (i.e., the side facing the central axis of the resonant device 400) is a straight surface. In another embodiment, the inner side of the surrounding portion can be a sloped surface.

[0136] In this embodiment, the cavity 403 is located inside the side cavity 409. In this embodiment, the electrode layer 405 is located on the side cavity 409 and has an overlapping portion with the side cavity 409.

[0137] It should be noted that the acoustic impedance of the vacuum state or air within the side cavity 409 is less than the acoustic impedance of the electrode layer 405, and the acoustic wave of the transverse mode is reflected at the junction of the side cavity 409 and the electrode layer 405, thereby blocking the leaky wave propagating towards the intermediate layer 402 in the transverse mode and improving the Q value.

[0138] Figure 4b It is a top view structural schematic diagram of a bulk acoustic wave resonant device 400 according to an embodiment of the present invention.

[0139] AsFigure 4b As shown, in this embodiment, the peripheral edge portion 408a is annular. In this embodiment, the peripheral edge portion 408a is octagonal. It should be noted that other shaped peripheral edge portions known to those skilled in the art, such as hexagonal, pentagonal, etc., can also be applied to the embodiments of the present invention.

[0140] As Figure 4b shown, in this embodiment, the cavity 403 is octagonal. It should be noted that other shaped cavities known to those skilled in the art, such as hexagonal, pentagonal, etc., can also be applied to the embodiments of the present invention. In this embodiment, the side cavity 409 is adjacent to the first side of the cavity 403.

[0141] Figure 5a is a schematic cross-sectional view of structure A of a bulk acoustic wave resonator device 500 according to an embodiment of the present invention.

[0142] As Figure 5a shown, an embodiment of the present invention provides a bulk acoustic wave resonator device 500, including: a substrate 501; an intermediate layer 502 located on the substrate 501, the upper surface side of the intermediate layer 502 including a cavity 503 and a groove 504, wherein the groove 504 is located on one side of the cavity 503 and communicates with the cavity 503, and the depth of the groove 504 is less than the depth of the cavity 503; an edge structure 505 including a peripheral edge portion 505a located in the cavity 503 and an extension portion 505b, one end of the extension portion 505b is connected to the peripheral edge portion 505a, and the other end of the extension portion 505b is located in the groove 504; an electrode layer 506 located on the edge structure 505, a first end 506a of the electrode layer 506 is located in the cavity 503, and a second end 506b of the electrode layer 506 is located in the groove 504, wherein the depth of the groove 504 is equal to the sum of the thicknesses of the edge structure 505 and the electrode layer 506; a piezoelectric layer 507 located on the electrode layer 506 and the intermediate layer 502, covering the cavity 503, wherein the piezoelectric layer 507 includes a first side 507a and a second side 507b opposite to the first side 507a, and the electrode layer 506 and the intermediate layer 502 are located on the first side 507a; an electrode layer 508 located on the second side 507b and on the piezoelectric layer 507; wherein the peripheral edge portion 505a is located at the edge of the overlapping portion of the electrode layer 506 and the electrode layer 508; and a side cavity 509 located on the first side 507a, between the intermediate layer 502 and the piezoelectric layer 507, embedded in the intermediate layer 502 and communicating with the cavity 503, and the side cavity 509 contacts the piezoelectric layer 507; wherein the depth of the side cavity 509 is less than the depth of the cavity 503.

[0143] From Figure 5a It can be seen that the resonance region 510 (i.e., the overlapping region of the electrode layer 506 and the electrode layer 508) is suspended relative to the cavity 503 and has no overlapping portion with the intermediate layer 502, thereby blocking the leakage of acoustic waves in the horizontal direction at the edge of the resonance region 510 into the intermediate layer 502, and the Q value can be improved.

[0144] In this embodiment, the side cavity 509 is located outside the resonance region 510 in the horizontal direction.

[0145] In this embodiment, the material of the substrate 501 includes but is not limited to at least one of the following: silicon, silicon carbide, glass, gallium arsenide, gallium nitride, ceramics.

[0146] In this embodiment, the material of the intermediate layer 502 includes but is not limited to at least one of the following: polymer, insulating dielectric, polysilicon. In this embodiment, the polymer includes but is not limited to at least one of the following: benzocyclobutene (i.e., BCB), photosensitive epoxy resin photoresist (e.g., SU-8), polyimide. In this embodiment, the insulating dielectric includes but is not limited to at least one of the following: aluminum nitride, silicon dioxide, silicon nitride, titanium oxide.

[0147] In this embodiment, the material of the edge structure 505 includes metal. In this embodiment, the material of the edge structure 505 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, beryllium. In this embodiment, the material of the edge structure 505 is the same as the material of the electrode layer 506. In another embodiment, the material of the edge structure under the piezoelectric layer and the material of the lower electrode layer can be different.

[0148] In this embodiment, the surrounding portion 505a is located within the resonance region 510 and is the surrounding edge of the resonance region 510. It should be noted that the acoustic impedance of the edge portion 511 within the resonance region 510 is greater than the acoustic impedance of the intermediate portion 512 within the resonance region 510, and the acoustic impedance of the edge portion 511 is greater than the acoustic impedance of the non-resonance region, so that the acoustic waves of the transverse mode are reflected at the horizontal edge of the resonance region 510 and remain within the resonance region 510, and the Q value can be improved.

[0149] In this embodiment, the inner side of the surrounding portion 505a (i.e., the side facing the central axis of the resonance device 500) is a straight surface. In another embodiment, the inner side of the surrounding portion can be a sloped surface.

[0150] In this embodiment, the material of the electrode layer 506 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, beryllium.

[0151] In this embodiment, the piezoelectric layer 507 is a flat layer and also covers the upper surface side of the intermediate layer 502. In this embodiment, the material of the piezoelectric layer 507 includes, but is not limited to, at least one of the following: aluminum nitride, aluminum nitride alloy, gallium nitride, zinc oxide, lithium tantalate, lithium niobate, lead zirconate titanate, lead magnesium niobate - lead titanate.

[0152] In this embodiment, the piezoelectric layer 507 includes a plurality of crystal grains, and the plurality of crystal grains include a first crystal grain and a second crystal grain. Among them, the first crystal grain and the second crystal grain are any two crystal grains in the plurality of crystal grains. Those skilled in the art know that the crystal orientation, crystal plane, etc. of crystal grains can be represented based on a coordinate system.

[0153] In this embodiment, the first crystal grain can be represented based on a first three - dimensional coordinate system, and the second crystal grain can be represented based on a second three - dimensional coordinate system. Among them, the first three - dimensional coordinate system at least includes a first coordinate axis along a first direction and a third coordinate axis along a third direction, and the second three - dimensional coordinate system at least includes a second coordinate axis along a second direction and a fourth coordinate axis along a fourth direction. Among them, the first coordinate axis corresponds to the height of the first crystal grain, and the second coordinate axis corresponds to the height of the second crystal grain.

[0154] In this embodiment, the first direction and the second direction are the same or opposite. It should be noted that the first direction and the second direction being the same means that the included angle range between the vector along the first direction and the vector along the second direction includes 0 degrees to 5 degrees; the first direction and the second direction being opposite means that the included angle range between the vector along the first direction and the vector along the second direction includes 175 degrees to 180 degrees.

[0155] In another embodiment, the first three - dimensional coordinate system is an ac three - dimensional coordinate system, where the first coordinate axis is the first c - axis and the third coordinate axis is the first a - axis; the second three - dimensional coordinate system is an ac three - dimensional coordinate system, the second coordinate axis is the second c - axis, and the fourth coordinate axis is the second a - axis. Among them, the directions of the first c - axis and the second c - axis are the same or opposite.

[0156] In another embodiment, the first three - dimensional coordinate system further includes a fifth coordinate axis along a fifth direction, and the second three - dimensional coordinate system further includes a sixth coordinate axis along a sixth direction. In another embodiment, the first direction and the second direction are the same or opposite, and the third direction and the fourth direction are the same or opposite. It should be noted that the third direction and the fourth direction being the same means that the included angle range between the vector along the third direction and the vector along the fourth direction includes 0 degrees to 5 degrees; the third direction and the fourth direction being opposite means that the included angle range between the vector along the third direction and the vector along the fourth direction includes 175 degrees to 180 degrees.

[0157] In another embodiment, the first three-dimensional coordinate system is an xyz three-dimensional coordinate system, where the first coordinate axis is the first z-axis, the third coordinate axis is the first y-axis, and the fifth coordinate axis is the first x-axis; the second three-dimensional coordinate system is an xyz three-dimensional coordinate system, the second coordinate axis is the second z-axis, the fourth coordinate axis is the second y-axis, and the sixth coordinate axis is the second x-axis. In another embodiment, the first z-axis and the second z-axis point in the same direction, and the first y-axis and the second y-axis point in the same direction. In another embodiment, the first z-axis and the second z-axis point in opposite directions, and the first y-axis and the second y-axis point in opposite directions. In another embodiment, the first z-axis and the second z-axis point in the same direction, and the first y-axis and the second y-axis point in opposite directions. In another embodiment, the first z-axis and the second z-axis point in opposite directions, and the first y-axis and the second y-axis point in the same direction.

[0158] In this embodiment, the piezoelectric layer 507 includes a plurality of crystal grains, and the full width at half maximum of the rocking curve of the crystal formed by the plurality of crystal grains is less than 2.5 degrees.

[0159] It should be noted that forming the piezoelectric layer 507 on a plane can make the piezoelectric layer 507 not include crystal grains with obvious turning, thereby improving the electromechanical coupling coefficient of the resonant device and the Q value of the resonant device.

[0160] In this embodiment, the material of the electrode layer 508 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, and beryllium.

[0161] In this embodiment, the part of the electrode layer 506 that coincides with the electrode layer 508 is located within the cavity 503; the part of the electrode 508 that coincides with the electrode 506 is located above the cavity 503.

[0162] In this embodiment, the cavity 503 is located inside the side cavity 509. In this embodiment, the electrode layer 508 is located above the side cavity 509 and has an overlapping portion with the side cavity 509.

[0163] It should be noted that the acoustic impedance of the vacuum state or air in the side cavity 509 is less than the acoustic impedance of the piezoelectric layer 507, and the acoustic wave in the transverse mode is reflected at the junction of the side cavity 509 and the piezoelectric layer 507, thereby blocking the leakage wave propagating towards the intermediate layer 502 in the transverse mode and improving the Q value.

[0164] Figure 5b It is a schematic top view structure diagram of a bulk acoustic wave resonant device 500 according to an embodiment of the present invention.

[0165] As Figure 5bAs shown, in this embodiment, the surrounding edge portion 505a is annular. In this embodiment, the surrounding edge portion 505a is octagonal. It should be noted that other shaped surrounding edge portions known to those skilled in the art, such as hexagonal, pentagonal, etc., can also be applied to the embodiments of the present invention.

[0166] As Figure 5b As shown, in this embodiment, the cavity 503 is octagonal. It should be noted that other shaped cavities known to those skilled in the art, such as hexagonal, pentagonal, etc., can also be applied to the embodiments of the present invention. In this embodiment, the side cavity 509 is adjacent to the first side of the cavity 503.

[0167] Figure 6a It is a schematic cross-sectional view of structure A of a bulk acoustic wave resonator device 600 according to an embodiment of the present invention.

[0168] As Figure 6aAs shown in the figure, an embodiment of the present invention provides a bulk acoustic wave resonator device 600, which includes: a substrate 601; an intermediate layer 602 located on the substrate 601. The upper surface side of the intermediate layer 602 includes a cavity 603 and a groove 604. Among them, the groove 604 is located on one side of the cavity 603 and communicates with the cavity 603, and the depth of the groove 604 is less than the depth of the cavity 603; an edge structure 605, including a surrounding edge portion 605a located in the cavity 603 and an extending portion 605b. One end of the extending portion 605b is connected to the surrounding edge portion 605a, and the other end of the extending portion 605b is located in the groove 604; an electrode layer 606 located on the edge structure 605. The first end 606a of the electrode layer 606 is located in the cavity 603, and the second end 606b of the electrode layer 606 is located in the groove 604. Among them, the depth of the groove 604 is equal to the sum of the thicknesses of the edge structure 605 and the electrode layer 606; a piezoelectric layer 607 located on the electrode layer 606 and the intermediate layer 602, covering the cavity 603. Among them, the piezoelectric layer 607 includes a first side 607a and a second side 607b opposite to the first side 607a, and the electrode layer 606 and the intermediate layer 602 are located on the first side 607a; an electrode layer 608 located on the second side 607b, on the piezoelectric layer 607. Among them, the surrounding edge portion 605a is located at a partial edge of the overlapping portion of the electrode layer 606 and the electrode layer 608; an edge structure 609 located on the second side 607b, on the electrode layer 608. The piezoelectric layer 607 and the edge structure 609 are respectively located on both sides of the electrode layer 608. Among them, the edge structure 609 includes a surrounding edge portion 609a located on a partial edge of the overlapping portion of the electrode layer 608 and the electrode layer 606; among them, the surrounding edge portion 605a and the surrounding edge portion 609a partially overlap to form a surrounding edge; a side cavity 610 located on the first side 607a, between the intermediate layer 602 and the piezoelectric layer 607, embedded in the intermediate layer 602, and communicating with the cavity 603. The side cavity 610 contacts the piezoelectric layer 607; and a side cavity 611 located between the intermediate layer 602 and the edge structure 605, embedded in the intermediate layer 602, and communicating with the cavity 603; among them, the depth of the side cavity 610 is less than the depth of the cavity 603, and the depth of the side cavity 611 is less than the depth of the cavity 603.

[0169] From Figure 6aIt can be seen that the resonance region 612 (i.e., the overlapping region of the electrode layer 606 and the electrode layer 608) is suspended relative to the cavity 603 and has no overlapping portion with the intermediate layer 602, thereby blocking the leakage of acoustic waves at the horizontal edges of the resonance region 612 in the lateral mode into the intermediate layer 602, which can improve the Q value.

[0170] In this embodiment, the side cavities 610 and 611 are located outside the resonance region 612 in the horizontal direction.

[0171] In this embodiment, the material of the substrate 601 includes, but is not limited to, at least one of the following: silicon, silicon carbide, glass, gallium arsenide, gallium nitride, and ceramic.

[0172] In this embodiment, the material of the intermediate layer 602 includes, but is not limited to, at least one of the following: polymer, insulating dielectric, and polysilicon. In this embodiment, the polymer includes, but is not limited to, at least one of the following: benzocyclobutene (i.e., BCB), photosensitive epoxy resin photoresist (e.g., SU-8), and polyimide. In this embodiment, the insulating dielectric includes, but is not limited to, at least one of the following: aluminum nitride, silicon dioxide, silicon nitride, and titanium oxide.

[0173] In this embodiment, the material of the edge structure 605 includes metal. In this embodiment, the material of the edge structure 605 includes, but is not limited to, at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, and beryllium. In this embodiment, the material of the edge structure 605 is the same as the material of the electrode layer 606. In another embodiment, the material of the first edge structure under the piezoelectric layer and the material of the lower electrode layer can be different.

[0174] In this embodiment, the material of the electrode layer 606 includes, but is not limited to, at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, and beryllium.

[0175] In this embodiment, the piezoelectric layer 607 is a flat layer and also covers the upper surface side of the intermediate layer 602. In this embodiment, the material of the piezoelectric layer 607 includes, but is not limited to, at least one of the following: aluminum nitride, aluminum nitride alloy, gallium nitride, zinc oxide, lithium tantalate, lithium niobate, lead zirconate titanate, and lead magnesium niobate-lead titanate.

[0176] In this embodiment, the piezoelectric layer 607 includes a plurality of grains, and the plurality of grains include a first grain and a second grain, where the first grain and the second grain are any two grains among the plurality of grains. Those skilled in the art know that the crystal orientation, crystal plane, etc. of the grains can be represented based on a coordinate system.

[0177] In this embodiment, the first crystal grain can be represented based on a first three-dimensional coordinate system, and the second crystal grain can be represented based on a second three-dimensional coordinate system. Among them, the first three-dimensional coordinate system at least includes a first coordinate axis along a first direction and a third coordinate axis along a third direction, and the second three-dimensional coordinate system at least includes a second coordinate axis along a second direction and a fourth coordinate axis along a fourth direction. Among them, the first coordinate axis corresponds to the height of the first crystal grain, and the second coordinate axis corresponds to the height of the second crystal grain.

[0178] In this embodiment, the first direction and the second direction are the same or opposite. It should be noted that the first direction and the second direction being the same means that the included angle range between the vector along the first direction and the vector along the second direction includes 0 degrees to 5 degrees; the first direction and the second direction being opposite means that the included angle range between the vector along the first direction and the vector along the second direction includes 175 degrees to 180 degrees.

[0179] In another embodiment, the first three-dimensional coordinate system is an ac three-dimensional coordinate system, where the first coordinate axis is the first c-axis and the third coordinate axis is the first a-axis; the second three-dimensional coordinate system is an ac three-dimensional coordinate system, the second coordinate axis is the second c-axis, and the fourth coordinate axis is the second a-axis. Among them, the first c-axis and the second c-axis point in the same or opposite directions.

[0180] In another embodiment, the first three-dimensional coordinate system further includes a fifth coordinate axis along a fifth direction, and the second three-dimensional coordinate system further includes a sixth coordinate axis along a sixth direction. In another embodiment, the first direction and the second direction are the same or opposite, and the third direction and the fourth direction are the same or opposite. It should be noted that the third direction and the fourth direction being the same means that the included angle range between the vector along the third direction and the vector along the fourth direction includes 0 degrees to 5 degrees; the third direction and the fourth direction being opposite means that the included angle range between the vector along the third direction and the vector along the fourth direction includes 175 degrees to 180 degrees.

[0181] In another embodiment, the first three-dimensional coordinate system is an xyz three-dimensional coordinate system, wherein the first coordinate axis is the first z-axis, the third coordinate axis is the first y-axis, and the fifth coordinate axis is the first x-axis; the second three-dimensional coordinate system is an xyz three-dimensional coordinate system, the second coordinate axis is the second z-axis, the fourth coordinate axis is the second y-axis, and the sixth coordinate axis is the second x-axis. In another embodiment, the first z-axis and the second z-axis point in the same direction, and the first y-axis and the second y-axis point in the same direction. In another embodiment, the first z-axis and the second z-axis point in opposite directions, and the first y-axis and the second y-axis point in opposite directions. In another embodiment, the first z-axis and the second z-axis point in the same direction, and the first y-axis and the second y-axis point in opposite directions. In another embodiment, the first z-axis and the second z-axis point in opposite directions, and the first y-axis and the second y-axis point in the same direction.

[0182] In this embodiment, the piezoelectric layer 607 includes a plurality of crystal grains, and the full width at half maximum of the rocking curve of the crystal formed by the plurality of crystal grains is less than 2.5 degrees.

[0183] It should be noted that forming the piezoelectric layer 607 on a plane can make the piezoelectric layer 607 not include crystal grains with obvious turning, thereby improving the electromechanical coupling coefficient of the resonant device and the Q value of the resonant device.

[0184] In this embodiment, the material of the electrode layer 608 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, and beryllium.

[0185] In this embodiment, the part of the electrode layer 606 that coincides with the electrode layer 608 is located within the cavity 603; the part of the electrode layer 608 that coincides with the electrode layer 606 is located above the cavity 603.

[0186] In this embodiment, the material of the edge structure 609 includes metal. In this embodiment, the material of the edge structure 609 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, and beryllium. In this embodiment, the material of the edge structure 609 is the same as the material of the electrode layer 608. In another embodiment, the materials of the second edge structure above the piezoelectric layer and the upper electrode layer can be different.

[0187] In this embodiment, the surrounding edge part 605a is located within the resonant region 612, the surrounding edge part 609a is located within the resonant region 612, and the surrounding edge part 605a and the surrounding edge part 609a partially overlap to form the surrounding edge of the resonant region 612. It should be noted that the acoustic impedance of the edge part 613 within the resonant region 612 is greater than the acoustic impedance of the middle part 614 within the resonant region 612, and the acoustic impedance of the edge part 613 is greater than the acoustic impedance of the non-resonant region. As a result, the acoustic wave of the transverse mode is reflected at the horizontal edge of the resonant region 612 and remains within the resonant region 612, which can increase the Q value.

[0188] In this embodiment, the inner side of the surrounding edge part 605a (i.e., the side facing the central axis of the resonant device 600) is a straight surface, and the inner side of the surrounding edge part 609a is a straight surface. In another embodiment, the inner side of the surrounding edge part can be a sloped surface.

[0189] In this embodiment, the cavity 603 is located inside the side cavity 610, and the cavity 603 is also located inside the side cavity 611. In this embodiment, the electrode layer 608 is located above the side cavity 610 and has an overlapping part with the side cavity 610; the edge structure 605 is located on the side cavity 611 and has an overlapping part with the side cavity 611.

[0190] It should be noted that the acoustic impedance of the vacuum state or air inside the side cavity 610 is less than the acoustic impedance of the piezoelectric layer 607, and the acoustic impedance of the vacuum state or air inside the side cavity 611 is less than the acoustic impedance of the edge structure 605. The acoustic wave of the transverse mode is reflected at the junction of the side cavity 610 and the piezoelectric layer 607 and at the junction of the side cavity 611 and the edge structure 605, thereby blocking the leaky wave propagating towards the intermediate layer 602 in the transverse mode and improving the Q value.

[0191] Figure 6b It is a top view structural schematic diagram of a bulk acoustic wave resonant device 600 according to an embodiment of the present invention.

[0192] As Figure 6b shown, in this embodiment, the surrounding edge part 605a and the surrounding edge part 609a have an overlapping part 615 to form the surrounding edge of the resonant region 612 and block the leakage of transverse waves. In this embodiment, the surrounding edge formed by the surrounding edge part 605a and the surrounding edge part 609a is annular. In this embodiment, the surrounding edge formed by the surrounding edge part 605a and the surrounding edge part 609a is octagonal. It should be noted that other shapes of surrounding edges known to those skilled in the art, such as hexagons, pentagons, etc., can also be applied to the embodiments of the present invention.

[0193] As Figure 6bAs shown, in this embodiment, the cavity 603 is octagonal. It should be noted that cavities of other shapes known to those skilled in the art, such as hexagonal, pentagonal, etc., can also be applied to the embodiments of the present invention. In this embodiment, the side cavity 610 is adjacent to seven sides of the cavity 603, and the side cavity 611 is adjacent to the eighth side of the cavity 603.

[0194] Figure 6c It is a schematic cross-sectional view of structure B of a bulk acoustic wave resonator device 600 according to an embodiment of the present invention. Figure 6c It shows the cross-sectional view of structure B of the side cavity 610 and the overlapping portion 615.

[0195] Figure 7 is a schematic cross-sectional view of structure A of a bulk acoustic wave resonator device 700 according to an embodiment of the present invention.

[0196] As shown in FIG. 7, an embodiment of the present invention provides a bulk acoustic wave resonator device 700, which includes: a substrate 701; an intermediate layer 702 located on the substrate 701, the upper surface side of the intermediate layer 702 including a cavity 703 and a groove 704, wherein the groove 704 is located on one side of the cavity 703 and communicates with the cavity 703, and the depth of the groove 704 is less than the depth of the cavity 703; an edge structure 705 including a surrounding portion 705a located in the cavity 703 and an extending portion 705b, one end of the extending portion 705b being connected to the surrounding portion 705a and the other end of the extending portion 705b being located in the groove 704; an electrode layer 706 located on the edge structure 705, a first end 706a of the electrode layer 706 being located in the cavity 703 and a second end 706b of the electrode layer 706 being located in the groove 704, wherein the depth of the groove 704 is equal to the sum of the thicknesses of the edge structure 705 and the electrode layer 706; a piezoelectric layer 707 located on the electrode layer 706 and the intermediate layer 702 and covering the cavity 703, wherein the piezoelectric layer 707 includes a first side 707a and a second side 707b opposite to the first side 707a, and the electrode layer 706 and the intermediate layer 702 are located on the first side 707a; an electrode layer 708 located on the second side 707b and on the piezoelectric layer 707, wherein the surrounding portion 705a is located at the edge of the overlapping portion of the electrode layer 706 and the electrode layer 708; an edge structure 709 located on the second side 707b and on the electrode layer 708, the piezoelectric layer 707 and the edge structure 709 being located on both sides of the electrode layer 708 respectively, wherein the edge structure 709 includes a surrounding portion 709a located on the edge of the overlapping portion of the electrode layer 708 and the electrode layer 706; wherein the surrounding portion 705a and the surrounding portion 709a overlap to form a surrounding edge; a side cavity 710 located on the first side 707a, between the intermediate layer 702 and the piezoelectric layer 707, embedded in the intermediate layer 702 and communicating with the cavity 703, the side cavity 710 contacting the piezoelectric layer 707; and a side cavity 711 located between the intermediate layer 702 and the edge structure 705, embedded in the intermediate layer 702 and communicating with the cavity 703; wherein the depth of the side cavity 710 is less than the depth of the cavity 703, and the depth of the side cavity 711 is less than the depth of the cavity 703.

[0197] By Figure 7aIt can be seen that the resonance region 712 (i.e., the overlapping region of the electrode layer 706 and the electrode layer 708) is suspended relative to the cavity 703 and has no overlapping portion with the intermediate layer 702, thereby blocking the leakage of acoustic waves at the horizontal edges of the resonance region 712 in the lateral mode into the intermediate layer 702, which can improve the Q value.

[0198] In this embodiment, the side cavities 710 and 711 are located outside the resonance region 712 in the horizontal direction.

[0199] In this embodiment, the material of the substrate 701 includes, but is not limited to, at least one of the following: silicon, silicon carbide, glass, gallium arsenide, gallium nitride, ceramic.

[0200] In this embodiment, the material of the intermediate layer 702 includes, but is not limited to, at least one of the following: polymer, insulating dielectric, polysilicon. In this embodiment, the polymer includes, but is not limited to, at least one of the following: benzocyclobutene (i.e., BCB), photosensitive epoxy resin photoresist (e.g., SU-8), polyimide. In this embodiment, the insulating dielectric includes, but is not limited to, at least one of the following: aluminum nitride, silicon dioxide, silicon nitride, titanium oxide.

[0201] In this embodiment, the material of the edge structure 705 includes metal. In this embodiment, the material of the edge structure 705 includes, but is not limited to, at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, beryllium. In this embodiment, the material of the edge structure 705 is the same as the material of the electrode layer 706. In another embodiment, the material of the first edge structure under the piezoelectric layer and the material of the lower electrode layer can be different.

[0202] In this embodiment, the material of the electrode layer 706 includes, but is not limited to, at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, beryllium.

[0203] In this embodiment, the piezoelectric layer 707 is a flat layer and also covers the upper surface side of the intermediate layer 702. In this embodiment, the material of the piezoelectric layer 707 includes, but is not limited to, at least one of the following: aluminum nitride, aluminum nitride alloy, gallium nitride, zinc oxide, lithium tantalate, lithium niobate, lead zirconate titanate, lead magnesium niobate - lead titanate.

[0204] In this embodiment, the piezoelectric layer 707 includes a plurality of grains, and the plurality of grains include a first grain and a second grain, where the first grain and the second grain are any two grains among the plurality of grains. Those skilled in the art know that the crystal orientation, crystal plane, etc. of the grains can be represented based on a coordinate system.

[0205] In this embodiment, the first crystal grain can be represented based on a first three-dimensional coordinate system, and the second crystal grain can be represented based on a second three-dimensional coordinate system. Wherein, the first three-dimensional coordinate system at least includes a first coordinate axis along a first direction and a third coordinate axis along a third direction, and the second three-dimensional coordinate system at least includes a second coordinate axis along a second direction and a fourth coordinate axis along a fourth direction. Wherein, the first coordinate axis corresponds to the height of the first crystal grain, and the second coordinate axis corresponds to the height of the second crystal grain.

[0206] In this embodiment, the first direction and the second direction are the same or opposite. It should be noted that the first direction and the second direction being the same means that the included angle range between the vector along the first direction and the vector along the second direction includes 0 degrees to 5 degrees; the first direction and the second direction being opposite means that the included angle range between the vector along the first direction and the vector along the second direction includes 175 degrees to 180 degrees.

[0207] In another embodiment, the first three-dimensional coordinate system is an ac three-dimensional coordinate system, where the first coordinate axis is the first c-axis and the third coordinate axis is the first a-axis; the second three-dimensional coordinate system is an ac three-dimensional coordinate system, the second coordinate axis is the second c-axis, and the fourth coordinate axis is the second a-axis. Wherein, the first c-axis and the second c-axis point in the same or opposite directions.

[0208] In another embodiment, the first three-dimensional coordinate system further includes a fifth coordinate axis along a fifth direction, and the second three-dimensional coordinate system further includes a sixth coordinate axis along a sixth direction. In another embodiment, the first direction and the second direction are the same or opposite, and the third direction and the fourth direction are the same or opposite. It should be noted that the third direction and the fourth direction being the same means that the included angle range between the vector along the third direction and the vector along the fourth direction includes 0 degrees to 5 degrees; the third direction and the fourth direction being opposite means that the included angle range between the vector along the third direction and the vector along the fourth direction includes 175 degrees to 180 degrees.

[0209] In another embodiment, the first three-dimensional coordinate system is an xyz three-dimensional coordinate system, where the first coordinate axis is the first z-axis, the third coordinate axis is the first y-axis, and the fifth coordinate axis is the first x-axis; the second three-dimensional coordinate system is an xyz three-dimensional coordinate system, the second coordinate axis is the second z-axis, the fourth coordinate axis is the second y-axis, and the sixth coordinate axis is the second x-axis. In another embodiment, the first z-axis and the second z-axis point in the same direction, and the first y-axis and the second y-axis point in the same direction. In another embodiment, the first z-axis and the second z-axis point in opposite directions, and the first y-axis and the second y-axis point in opposite directions. In another embodiment, the first z-axis and the second z-axis point in the same direction, and the first y-axis and the second y-axis point in opposite directions. In another embodiment, the first z-axis and the second z-axis point in opposite directions, and the first y-axis and the second y-axis point in the same direction.

[0210] In this embodiment, the piezoelectric layer 707 includes a plurality of crystal grains, and the full width at half maximum of the rocking curve of the crystal formed by the plurality of crystal grains is less than 2.5 degrees.

[0211] It should be noted that forming the piezoelectric layer 707 on a plane can make the piezoelectric layer 707 not include crystal grains with obvious turning, thereby improving the electromechanical coupling coefficient of the resonant device and the Q value of the resonant device.

[0212] In this embodiment, the material of the electrode layer 708 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, beryllium.

[0213] In this embodiment, the part of the electrode layer 706 that coincides with the electrode layer 708 is located within the cavity 703; the part of the electrode 708 that coincides with the electrode 706 is located above the cavity 703.

[0214] In this embodiment, the material of the edge structure 709 includes metal. In this embodiment, the material of the edge structure 709 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, beryllium. In this embodiment, the material of the edge structure 709 is the same as the material of the electrode layer 708. In another embodiment, the materials of the second edge structure above the piezoelectric layer and the upper electrode layer can be different.

[0215] In this embodiment, the surrounding edge part 705a is located within the resonant region 712, the surrounding edge part 709a is located within the resonant region 712, and the surrounding edge part 705a coincides with the surrounding edge part 709a to form the surrounding edge of the resonant region 712. It should be noted that the acoustic impedance of the edge part 713 within the resonant region 712 is greater than the acoustic impedance of the middle part 714 within the resonant region 712, and the acoustic impedance of the edge part 713 is greater than the acoustic impedance of the non-resonant region, so that the acoustic wave of the transverse mode is reflected at the horizontal edge of the resonant region 712 and remains within the resonant region 712, which can improve the Q value.

[0216] In this embodiment, the inner side (i.e., the side facing the central axis of the resonant device 700) of the surrounding edge part 705a is a straight surface, and the inner side of the surrounding edge part 709a is a straight surface. In another embodiment, the inner side of the surrounding edge part can be a sloped surface.

[0217] In this embodiment, the cavity 703 is located inside the side cavity 710, and the cavity 703 is also located inside the side cavity 711. In this embodiment, the electrode layer 708 is located above the side cavity 710 and has an overlapping part with the side cavity 710; the edge structure 705 is located on the side cavity 711 and has an overlapping part with the side cavity 711.

[0218] It should be noted that the acoustic impedance of the vacuum state or air inside the side cavity 710 is less than the acoustic impedance of the piezoelectric layer 707, and the acoustic impedance of the vacuum state or air inside the side cavity 711 is less than the acoustic impedance of the edge structure 705. The acoustic wave of the transverse mode is reflected at the junction of the side cavity 710 and the piezoelectric layer 707 and at the junction of the side cavity 711 and the edge structure 705, thereby blocking the leakage wave propagating towards the intermediate layer 702 in the transverse mode and improving the Q value.

[0219] Figure 7b It is a top view structural schematic diagram of a bulk acoustic wave resonant device 700 according to an embodiment of the present invention.

[0220] As Figure 7b shown, in this embodiment, the surrounding edge part 705a coincides with the surrounding edge part 709a to form the surrounding edge of the resonant region 712, blocking the leakage of transverse waves. In this embodiment, the surrounding edge formed by the surrounding edge part 705a and the surrounding edge part 709a is annular. In this embodiment, the surrounding edge formed by the surrounding edge part 705a and the surrounding edge part 709a is octagonal. It should be noted that other shaped surrounding edges known to those skilled in the art, such as hexagons, pentagons, etc., can also be applied to the embodiments of the present invention.

[0221] As Figure 7bAs shown, in this embodiment, the cavity 703 is octagonal. It should be noted that cavities of other shapes known to those skilled in the art, such as hexagonal, pentagonal, etc., can also be applied to the embodiments of the present invention. In this embodiment, the side cavity 710 is adjacent to five sides of the cavity 703, and the side cavity 711 is adjacent to the sixth side of the cavity 703.

[0222] Figure 8 It is a schematic cross-sectional structure diagram of section A of a bulk acoustic wave resonator device 800 according to an embodiment of the present invention.

[0223] As Figure 8 shown, an embodiment of the present invention provides a bulk acoustic wave resonator device 800, including: a substrate 801; an intermediate layer 802 located on the substrate 801, the upper surface side of the intermediate layer 802 including a cavity 803 and a groove 804, wherein the groove 804 is located on one side of the cavity 803 and communicates with the cavity 803, and the depth of the groove 804 is less than the depth of the cavity 803; an electrode layer 805, a first end 805a of the electrode layer 805 is located in the cavity 803, and a second end 805b of the electrode layer 805 is located in the groove 804, wherein the depth of the groove 804 is equal to the thickness of the electrode layer 805; a piezoelectric layer 806 located on the electrode layer 805 and the intermediate layer 802, covering the cavity 803, wherein the piezoelectric layer 806 includes a first side 806a and a second side 806b opposite to the first side 806a, and the electrode layer 805 and the intermediate layer 802 are located on the first side 806a; an electrode layer 807 located on the second side 806b and on the piezoelectric layer 806; an edge structure 808 located on the second side 806b and on the piezoelectric layer 806, wherein the edge structure 808 includes a surrounding portion 808a, the electrode layer 807 is located in the middle of the surrounding portion 808a (i.e., the inner side, the side facing the central axis of the resonator device 800), and the surrounding portion 808a coincides with the electrode layer 805; and a side cavity 809 located between the intermediate layer 802 and the electrode layer 805, embedded in the intermediate layer 802, and communicating with the cavity 803; wherein the depth of the side cavity 809 is less than the depth of the cavity 803.

[0224] From Figure 8 it can be seen that the resonance region 810 (i.e., the overlapping region of the electrode layer 805, the electrode layer 807, and the surrounding portion 808a) is suspended relative to the cavity 803 and has no overlapping portion with the intermediate layer 802, thereby blocking the leakage of acoustic waves at the horizontal edges of the resonance region 810 in the lateral mode into the intermediate layer 802, which can improve the Q value.

[0225] In this embodiment, the side cavity 809 is located outside the resonant region 810 in the horizontal direction.

[0226] In this embodiment, the material of the substrate 801 includes but is not limited to at least one of the following: silicon, silicon carbide, glass, gallium arsenide, gallium nitride, and ceramics.

[0227] In this embodiment, the material of the intermediate layer 802 includes but is not limited to at least one of the following: polymers, insulating dielectrics, and polysilicon. In this embodiment, the polymers include but are not limited to at least one of the following: benzocyclobutene (i.e., BCB), photosensitive epoxy resin photoresist (e.g., SU-8), and polyimide. In this embodiment, the insulating dielectrics include but are not limited to at least one of the following: aluminum nitride, silicon dioxide, silicon nitride, and titanium oxide.

[0228] In this embodiment, the material of the electrode layer 805 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, and beryllium.

[0229] In this embodiment, the piezoelectric layer 806 is a flat layer and also covers the upper surface side of the intermediate layer 802. In this embodiment, the material of the piezoelectric layer 806 includes but is not limited to at least one of the following: aluminum nitride, aluminum nitride alloy, gallium nitride, zinc oxide, lithium tantalate, lithium niobate, lead zirconate titanate, and lead magnesium niobate-titanate.

[0230] In this embodiment, the piezoelectric layer 806 includes a plurality of grains, and the plurality of grains include a first grain and a second grain. Among them, the first grain and the second grain are any two grains in the plurality of grains. Those skilled in the art know that the crystal orientation, crystal plane, etc. of the grains can be represented based on a coordinate system.

[0231] In this embodiment, the first grain can be represented based on a first three-dimensional coordinate system, and the second grain can be represented based on a second three-dimensional coordinate system. Among them, the first three-dimensional coordinate system includes at least a first coordinate axis along a first direction and a third coordinate axis along a third direction, and the second three-dimensional coordinate system includes at least a second coordinate axis along a second direction and a fourth coordinate axis along a fourth direction. Among them, the first coordinate axis corresponds to the height of the first grain, and the second coordinate axis corresponds to the height of the second grain.

[0232] In this embodiment, the first direction and the second direction are the same or opposite. It should be noted that the first direction and the second direction being the same means that the included angle range between the vector along the first direction and the vector along the second direction includes 0 degrees to 5 degrees; the first direction and the second direction being opposite means that the included angle range between the vector along the first direction and the vector along the second direction includes 175 degrees to 180 degrees.

[0233] In another embodiment, the first three-dimensional coordinate system is an ac three-dimensional coordinate system, where the first coordinate axis is the first c-axis, and the third coordinate axis is the first a-axis; the second three-dimensional coordinate system is an ac three-dimensional coordinate system, the second coordinate axis is the second c-axis, and the fourth coordinate axis is the second a-axis, where the first c-axis and the second c-axis point in the same or opposite directions.

[0234] In another embodiment, the first three-dimensional coordinate system further includes a fifth coordinate axis along a fifth direction, and the second three-dimensional coordinate system further includes a sixth coordinate axis along a sixth direction. In another embodiment, the first direction and the second direction are the same or opposite, and the third direction and the fourth direction are the same or opposite. It should be noted that the third direction and the fourth direction being the same means that the included angle range between the vector along the third direction and the vector along the fourth direction includes 0 degrees to 5 degrees; the third direction and the fourth direction being opposite means that the included angle range between the vector along the third direction and the vector along the fourth direction includes 175 degrees to 180 degrees.

[0235] In another embodiment, the first three-dimensional coordinate system is an xyz three-dimensional coordinate system, where the first coordinate axis is the first z-axis, the third coordinate axis is the first y-axis, and the fifth coordinate axis is the first x-axis; the second three-dimensional coordinate system is an xyz three-dimensional coordinate system, the second coordinate axis is the second z-axis, the fourth coordinate axis is the second y-axis, and the sixth coordinate axis is the second x-axis. In another embodiment, the first z-axis and the second z-axis point in the same direction, and the first y-axis and the second y-axis point in the same direction. In another embodiment, the first z-axis and the second z-axis point in opposite directions, and the first y-axis and the second y-axis point in opposite directions. In another embodiment, the first z-axis and the second z-axis point in the same direction, and the first y-axis and the second y-axis point in opposite directions. In another embodiment, the first z-axis and the second z-axis point in opposite directions, and the first y-axis and the second y-axis point in the same direction.

[0236] In this embodiment, the piezoelectric layer 806 includes a plurality of crystal grains, and the full width at half maximum of the rocking curve of the crystal formed by the plurality of crystal grains is less than 2.5 degrees.

[0237] It should be noted that forming the piezoelectric layer 806 on a plane can make the piezoelectric layer 806 not include crystal grains with obvious turning, thereby improving the electromechanical coupling coefficient of the resonant device and the Q value of the resonant device.

[0238] In this embodiment, the material of the electrode layer 807 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, beryllium.

[0239] In this embodiment, the overlapping portion of the electrode layer 805 and the electrode layer 807 is located within the cavity 803; the overlapping portion of the electrode 807 and the electrode 805 is located above the cavity 803.

[0240] In this embodiment, the material of the edge structure 808 includes metal. In this embodiment, the material of the edge structure 808 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, beryllium. In this embodiment, the material of the edge structure 808 is the same as the material of the electrode layer 807. In another embodiment, the material of the edge structure on the piezoelectric layer and the material of the upper electrode layer may be different.

[0241] In this embodiment, the thickness of the edge structure 808 is greater than the thickness of the electrode layer 807. In another embodiment, the thickness of the edge structure on the piezoelectric layer is less than the thickness of the upper electrode layer. In another embodiment, the thickness of the edge structure on the piezoelectric layer is equal to the thickness of the upper electrode layer.

[0242] In this embodiment, the surrounding portion 808a is located within the resonance region 810 and serves as the surrounding edge of the resonance region 810. It should be noted that the acoustic impedance of the edge portion 811 within the resonance region 810 is greater than the acoustic impedance of the middle portion 812 within the resonance region 810, and the acoustic impedance of the edge portion 811 is greater than the acoustic impedance of the non-resonance region, so that the acoustic wave of the transverse mode is reflected at the horizontal edge of the resonance region 810 and remains within the resonance region 810, which can improve the Q value.

[0243] In this embodiment, the inner side of the surrounding portion 808a is a straight surface. In another embodiment, the inner side of the surrounding portion may be a sloped surface.

[0244] In this embodiment, the cavity 803 is located inside the side cavity 809. In this embodiment, the electrode layer 805 is located on the side cavity 809 and has an overlapping portion with the side cavity 809.

[0245] It should be noted that the acoustic impedance of the vacuum state or air within the side cavity 809 is less than the acoustic impedance of the electrode layer 805, and the acoustic wave of the transverse mode is reflected at the junction of the side cavity 809 and the electrode layer 805, thereby blocking the leakage wave propagating towards the intermediate layer 802 in the transverse mode and improving the Q value.

[0246] Figure 9 It is a schematic cross-sectional view of the structure of section A of a bulk acoustic wave resonator device 900 according to an embodiment of the present invention.

[0247] As Figure 9As shown in the figure, an embodiment of the present invention provides a bulk acoustic wave resonator device 900, which includes: a substrate 901; an intermediate layer 902 located on the substrate 901. The upper surface side of the intermediate layer 902 includes a cavity 903 and a groove 904. Among them, the groove 904 is located on one side of the cavity 903 and communicates with the cavity 903, and the depth of the groove 904 is less than the depth of the cavity 903; an electrode layer 905 located in the cavity 903; an edge structure 906 including a surrounding portion 906a located in the cavity 903, the electrode layer 905 is located in the middle of the surrounding portion 906a (i.e., the inner side, the side facing the central axis of the resonator device 900), and an extension portion 906b. One end of the extension portion 906b is connected to the surrounding portion 906a, and the other end of the extension portion 906b is located in the groove 904. Among them, the depth of the groove 904 is equal to the thickness of the edge structure 906; a piezoelectric layer 907 located on the electrode layer 905, the edge structure 906 and the intermediate layer 902, covering the cavity 903. Among them, the piezoelectric layer 907 includes a first side 907a and a second side 907b opposite to the first side 907a. The electrode layer 905, the edge structure 906 and the intermediate layer 902 are located on the first side 907a; an electrode layer 908 located on the second side 907b, located on the piezoelectric layer 907, and the surrounding portion 906a coincides with the electrode layer 908; and a side cavity 909 located on the first side 907a, located between the intermediate layer 902 and the piezoelectric layer 907, embedded in the intermediate layer 902, and communicating with the cavity 903. The side cavity 909 contacts the piezoelectric layer 907; among them, the depth of the side cavity 909 is less than the depth of the cavity 903.

[0248] It can be seen from Figure 9 that the resonance region 910 (i.e., the overlapping region of the electrode layer 905 and the surrounding portion 906a with the electrode layer 908) is suspended relative to the cavity 903 and has no overlapping portion with the intermediate layer 902, thereby blocking the leakage of acoustic waves at the horizontal edge of the resonance region 910 into the intermediate layer 902, and the Q value can be improved.

[0249] In this embodiment, the side cavity 909 is located outside the resonance region 910 in the horizontal direction.

[0250] In this embodiment, the material of the substrate 901 includes but is not limited to at least one of the following: silicon, silicon carbide, glass, gallium arsenide, gallium nitride, ceramic.

[0251] In this embodiment, the material of the intermediate layer 902 includes, but is not limited to, at least one of the following: polymers, insulating dielectrics, polysilicon. In this embodiment, the polymers include, but are not limited to, at least one of the following: benzocyclobutene (i.e., BCB), photosensitive epoxy resin photoresist (e.g., SU-8), polyimide. In this embodiment, the insulating dielectrics include, but are not limited to, at least one of the following: aluminum nitride, silicon dioxide, silicon nitride, titanium oxide.

[0252] In this embodiment, the material of the electrode layer 905 includes, but is not limited to, at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, beryllium.

[0253] In this embodiment, the material of the edge structure 906 includes metal. In this embodiment, the material of the edge structure 906 includes, but is not limited to, at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, beryllium. In this embodiment, the material of the edge structure 906 is the same as the material of the electrode layer 905. In another embodiment, the material of the edge structure under the piezoelectric layer and the material of the lower electrode layer may be different.

[0254] In this embodiment, the thickness of the edge structure 906 is greater than the thickness of the electrode layer 905. In another embodiment, the thickness of the edge structure under the piezoelectric layer is less than the thickness of the lower electrode layer. In another embodiment, the thickness of the edge structure under the piezoelectric layer is equal to the thickness of the lower electrode layer.

[0255] In this embodiment, the surrounding edge portion 906a is located within the resonant region 910 and is the surrounding edge of the resonant region 910. It should be noted that the acoustic impedance of the edge portion 911 within the resonant region 910 is greater than the acoustic impedance of the middle portion 912 within the resonant region 910, and the acoustic impedance of the edge portion 911 is greater than the acoustic impedance of the non-resonant region, so that the acoustic wave of the transverse mode is reflected at the horizontal edge of the resonant region 910 and remains within the resonant region 910, which can improve the Q value.

[0256] In this embodiment, the inner side of the surrounding edge portion 906a is a straight surface. In another embodiment, the inner side of the surrounding edge portion may be a sloped surface.

[0257] In this embodiment, the piezoelectric layer 907 is a flat layer and also covers the upper surface side of the intermediate layer 902. In this embodiment, the material of the piezoelectric layer 907 includes, but is not limited to, at least one of the following: aluminum nitride, aluminum nitride alloy, gallium nitride, zinc oxide, lithium tantalate, lithium niobate, lead zirconate titanate, lead magnesium niobate-titanate.

[0258] In this embodiment, the piezoelectric layer 907 includes a plurality of crystal grains, and the plurality of crystal grains include a first crystal grain and a second crystal grain, where the first crystal grain and the second crystal grain are any two crystal grains among the plurality of crystal grains. Those skilled in the art know that the crystal orientation, crystal plane, etc. of crystal grains can be represented based on a coordinate system.

[0259] In this embodiment, the first crystal grain can be represented based on a first three-dimensional coordinate system, and the second crystal grain can be represented based on a second three-dimensional coordinate system, where the first three-dimensional coordinate system at least includes a first coordinate axis along a first direction and a third coordinate axis along a third direction, and the second three-dimensional coordinate system at least includes a second coordinate axis along a second direction and a fourth coordinate axis along a fourth direction, where the first coordinate axis corresponds to the height of the first crystal grain, and the second coordinate axis corresponds to the height of the second crystal grain.

[0260] In this embodiment, the first direction and the second direction are the same or opposite. It should be noted that the first direction and the second direction being the same means that the included angle range between the vector along the first direction and the vector along the second direction includes 0 degrees to 5 degrees; the first direction and the second direction being opposite means that the included angle range between the vector along the first direction and the vector along the second direction includes 175 degrees to 180 degrees.

[0261] In another embodiment, the first three-dimensional coordinate system is an ac three-dimensional coordinate system, where the first coordinate axis is the first c-axis, and the third coordinate axis is the first a-axis; the second three-dimensional coordinate system is an ac three-dimensional coordinate system, the second coordinate axis is the second c-axis, and the fourth coordinate axis is the second a-axis, where the first c-axis and the second c-axis point in the same or opposite directions.

[0262] In another embodiment, the first three-dimensional coordinate system further includes a fifth coordinate axis along a fifth direction, and the second three-dimensional coordinate system further includes a sixth coordinate axis along a sixth direction. In another embodiment, the first direction and the second direction are the same or opposite, and the third direction and the fourth direction are the same or opposite. It should be noted that the third direction and the fourth direction being the same means that the included angle range between the vector along the third direction and the vector along the fourth direction includes 0 degrees to 5 degrees; the third direction and the fourth direction being opposite means that the included angle range between the vector along the third direction and the vector along the fourth direction includes 175 degrees to 180 degrees.

[0263] In another embodiment, the first three-dimensional coordinate system is an xyz three-dimensional coordinate system, where the first coordinate axis is the first z-axis, the third coordinate axis is the first y-axis, and the fifth coordinate axis is the first x-axis; the second three-dimensional coordinate system is an xyz three-dimensional coordinate system, the second coordinate axis is the second z-axis, the fourth coordinate axis is the second y-axis, and the sixth coordinate axis is the second x-axis. In another embodiment, the first z-axis and the second z-axis point in the same direction, and the first y-axis and the second y-axis point in the same direction. In another embodiment, the first z-axis and the second z-axis point in opposite directions, and the first y-axis and the second y-axis point in opposite directions. In another embodiment, the first z-axis and the second z-axis point in the same direction, and the first y-axis and the second y-axis point in opposite directions. In another embodiment, the first z-axis and the second z-axis point in opposite directions, and the first y-axis and the second y-axis point in the same direction.

[0264] In this embodiment, the piezoelectric layer 907 includes a plurality of grains, and the full width at half maximum of the rocking curve of the crystal formed by the plurality of grains is less than 2.5 degrees.

[0265] It should be noted that forming the piezoelectric layer 907 on a plane can make the piezoelectric layer 907 not include grains with obvious turning, thereby improving the electromechanical coupling coefficient of the resonant device and the Q value of the resonant device.

[0266] In this embodiment, the material of the electrode layer 908 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, beryllium.

[0267] In this embodiment, the part of the electrode layer 905 that coincides with the electrode layer 908 is located in the cavity 903; the part of the electrode 908 that coincides with the electrode 905 is located above the cavity 903.

[0268] In this embodiment, the cavity 903 is located inside the side cavity 909. In this embodiment, the electrode layer 908 is located above the side cavity 909 and has an overlapping portion with the side cavity 909.

[0269] It should be noted that the acoustic impedance of the vacuum state or air in the side cavity 909 is less than the acoustic impedance of the piezoelectric layer 907, and the acoustic wave in the transverse mode is reflected at the junction of the side cavity 909 and the piezoelectric layer 907, thereby blocking the leakage wave propagating towards the intermediate layer 902 in the transverse mode and improving the Q value.

[0270] Figure 10a It is a schematic cross-sectional view of the structure of section A of a bulk acoustic wave resonator 1000 according to an embodiment of the present invention.

[0271] Such as Figure 10aAs shown in the figure, an embodiment of the present invention provides a bulk acoustic wave resonator device 1000, which includes: a substrate 1001; an intermediate layer 1002 located on the substrate 1001, the upper surface side of the intermediate layer 1002 includes a cavity 1003 and a groove 1004, wherein the groove 1004 is located on one side of the cavity 1003 and communicates with the cavity 1003, and the depth of the groove 1004 is less than the depth of the cavity 1003; an electrode layer 1005 located in the cavity 1003; an edge structure 1006 including a surrounding portion 1006a located in the cavity 1003, beside a partial edge of the electrode layer 1005, the electrode layer 1005 is located inside the surrounding portion 1006a (i.e., on the side facing the central axis of the resonator device 1000), and an extension portion 1006b, one end of the extension portion 1006b is connected to the surrounding portion 1006a, and the other end of the extension portion 1006b is located in the groove 1004, wherein the depth of the groove 1004 is equal to the thickness of the edge structure 1006; a piezoelectric layer 1007 located on the electrode layer 1005, the edge structure 1006, and the intermediate layer 1002, covering the cavity 1003, wherein the piezoelectric layer 1007 includes a first side 1007a and a second side 1007b opposite to the first side 1007a, and the electrode layer 1005, the edge structure 1006, and the intermediate layer 1002 are located on the first side 1007a; an electrode layer 1008 located on the second side 1007b and on the piezoelectric layer 1007, and the surrounding portion 1006a coincides with the electrode layer 1008; an edge structure 1009 located on the second side 1007b and on the piezoelectric layer 1007, wherein the edge structure 1009 includes a surrounding portion 1009a located beside a partial edge of the electrode layer 1008, the electrode layer 1008 is located inside the surrounding portion 1009a, and the surrounding portion 1009a coincides with the electrode layer 1005; wherein the surrounding portion 1006a and the surrounding portion 1009a partially coincide to form a surrounding edge; a side cavity 1010 located on the first side 1007a, between the intermediate layer 1002 and the piezoelectric layer 1007, embedded in the intermediate layer 1002 and communicating with the cavity 1003, and the side cavity 1010 contacts the piezoelectric layer 1007; and a side cavity 1011 located between the intermediate layer 1002 and the edge structure 1006, embedded in the intermediate layer 1002 and communicating with the cavity 1003; wherein the depth of the side cavity 1010 is less than the depth of the cavity 1003, and the depth of the side cavity 1011 is less than the depth of the cavity 1003.

[0272] by Figure 10aIt can be seen that the resonance region 1012 (i.e., the overlapping region of the electrode layer 1005 and the peripheral edge portion 1006a with the electrode layer 1008 and the peripheral edge portion 1009a) is suspended relative to the cavity 1003 and has no overlapping portion with the intermediate layer 1002, thereby blocking the leakage of acoustic waves from the horizontal edge side of the resonance region 1012 in the lateral mode into the intermediate layer 1002, which can improve the Q value.

[0273] In this embodiment, the side cavities 1010 and 1011 are located outside the resonance region 1012 in the horizontal direction.

[0274] In this embodiment, the material of the substrate 1001 includes but is not limited to at least one of the following: silicon, silicon carbide, glass, gallium arsenide, gallium nitride, ceramic.

[0275] In this embodiment, the material of the intermediate layer 1002 includes but is not limited to at least one of the following: polymer, insulating dielectric, polysilicon. In this embodiment, the polymer includes but is not limited to at least one of the following: benzocyclobutene (i.e., BCB), photosensitive epoxy resin photoresist (e.g., SU-8), polyimide. In this embodiment, the insulating dielectric includes but is not limited to at least one of the following: aluminum nitride, silicon dioxide, silicon nitride, titanium oxide.

[0276] In this embodiment, the material of the electrode layer 1005 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, beryllium.

[0277] In this embodiment, the material of the edge structure 1006 is metal. In this embodiment, the material of the edge structure 1006 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, beryllium. In this embodiment, the material of the edge structure 1006 is the same as that of the electrode layer 1005. In another embodiment, the materials of the first edge structure under the piezoelectric layer and the lower electrode layer can be different.

[0278] In this embodiment, the thickness of the edge structure 1006 is greater than that of the electrode layer 1005. In another embodiment, the thickness of the first edge structure under the piezoelectric layer is less than that of the lower electrode layer. In another embodiment, the thickness of the first edge structure under the piezoelectric layer is equal to that of the lower electrode layer.

[0279] In this embodiment, the piezoelectric layer 1007 is a flat layer and also covers the upper surface side of the intermediate layer 1002. In this embodiment, the material of the piezoelectric layer 1007 includes but is not limited to at least one of the following: aluminum nitride, aluminum nitride alloy, gallium nitride, zinc oxide, lithium tantalate, lithium niobate, lead zirconate titanate, lead magnesium niobate - lead titanate.

[0280] In this embodiment, the piezoelectric layer 1007 includes a plurality of crystal grains, and the plurality of crystal grains include a first crystal grain and a second crystal grain. Among them, the first crystal grain and the second crystal grain are any two crystal grains among the plurality of crystal grains. Those skilled in the art know that the crystal orientation, crystal plane, etc. of crystal grains can be represented based on a coordinate system.

[0281] In this embodiment, the first crystal grain can be represented based on a first three-dimensional coordinate system, and the second crystal grain can be represented based on a second three-dimensional coordinate system. Among them, the first three-dimensional coordinate system at least includes a first coordinate axis along a first direction and a third coordinate axis along a third direction, and the second three-dimensional coordinate system at least includes a second coordinate axis along a second direction and a fourth coordinate axis along a fourth direction. Among them, the first coordinate axis corresponds to the height of the first crystal grain, and the second coordinate axis corresponds to the height of the second crystal grain.

[0282] In this embodiment, the first direction and the second direction are the same or opposite. It should be noted that the first direction and the second direction being the same means that the included angle range between the vector along the first direction and the vector along the second direction includes 0 degrees to 5 degrees; the first direction and the second direction being opposite means that the included angle range between the vector along the first direction and the vector along the second direction includes 175 degrees to 180 degrees.

[0283] In another embodiment, the first three-dimensional coordinate system is an ac three-dimensional coordinate system, where the first coordinate axis is the first c-axis and the third coordinate axis is the first a-axis; the second three-dimensional coordinate system is an ac three-dimensional coordinate system, the second coordinate axis is the second c-axis, and the fourth coordinate axis is the second a-axis, where the first c-axis and the second c-axis point in the same or opposite directions.

[0284] In another embodiment, the first three-dimensional coordinate system further includes a fifth coordinate axis along a fifth direction, and the second three-dimensional coordinate system further includes a sixth coordinate axis along a sixth direction. In another embodiment, the first direction and the second direction are the same or opposite, and the third direction and the fourth direction are the same or opposite. It should be noted that the third direction and the fourth direction being the same means that the included angle range between the vector along the third direction and the vector along the fourth direction includes 0 degrees to 5 degrees; the third direction and the fourth direction being opposite means that the included angle range between the vector along the third direction and the vector along the fourth direction includes 175 degrees to 180 degrees.

[0285] In another embodiment, the first three-dimensional coordinate system is an xyz three-dimensional coordinate system, where the first coordinate axis is the first z-axis, the third coordinate axis is the first y-axis, and the fifth coordinate axis is the first x-axis; the second three-dimensional coordinate system is an xyz three-dimensional coordinate system, the second coordinate axis is the second z-axis, the fourth coordinate axis is the second y-axis, and the sixth coordinate axis is the second x-axis. In another embodiment, the first z-axis and the second z-axis point in the same direction, and the first y-axis and the second y-axis point in the same direction. In another embodiment, the first z-axis and the second z-axis point in opposite directions, and the first y-axis and the second y-axis point in opposite directions. In another embodiment, the first z-axis and the second z-axis point in the same direction, and the first y-axis and the second y-axis point in opposite directions. In another embodiment, the first z-axis and the second z-axis point in opposite directions, and the first y-axis and the second y-axis point in the same direction.

[0286] In this embodiment, the piezoelectric layer 1007 includes a plurality of grains, and the full width at half maximum of the rocking curve of the crystal formed by the plurality of grains is less than 2.5 degrees.

[0287] It should be noted that forming the piezoelectric layer 1007 on a plane can make the piezoelectric layer 1007 not include grains with obvious turning, thereby improving the electromechanical coupling coefficient of the resonant device and the Q value of the resonant device.

[0288] In this embodiment, the material of the electrode layer 1008 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, and beryllium.

[0289] In this embodiment, the part of the electrode layer 1005 that coincides with the electrode layer 1008 is located within the cavity 1003; the part of the electrode 1008 that coincides with the electrode 1005 is located above the cavity 1003.

[0290] In this embodiment, the material of the edge structure 1009 includes metal. In this embodiment, the material of the edge structure 1009 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, and beryllium. In this embodiment, the material of the edge structure 1009 is the same as the material of the electrode layer 1008. In another embodiment, the material of the second edge structure on the piezoelectric layer and the material of the upper electrode layer can be different.

[0291] In this embodiment, the thickness of the edge structure 1009 is greater than the thickness of the electrode layer 1008. In another embodiment, the thickness of the second edge structure on the piezoelectric layer is less than the thickness of the upper electrode layer. In another embodiment, the thickness of the second edge structure on the piezoelectric layer is equal to the thickness of the upper electrode layer.

[0292] In this embodiment, the surrounding edge portion 1006a is located within the resonant region 1012, the surrounding edge portion 1009a is located within the resonant region 1012, and the surrounding edge portion 1006a and the surrounding edge portion 1009a partially overlap to form the surrounding edge of the resonant region 1012. It should be noted that the acoustic impedance of the edge portion 1013 in the resonant region 1012 is greater than the acoustic impedance of the middle portion 1014 in the resonant region 1012, and the acoustic impedance of the edge portion 1013 is greater than the acoustic impedance of the non-resonant region, so that the acoustic wave in the transverse mode is reflected at the horizontal edge of the resonant region 1012 and remains within the resonant region 1012, which can improve the Q value.

[0293] In this embodiment, the inner side of the surrounding edge portion 1006a is a straight surface, and the inner side of the surrounding edge portion 1009a is a straight surface. In another embodiment, the inner side of the surrounding edge portion can be a sloped surface.

[0294] In this embodiment, the cavity 1003 is located inside the side cavity 1010, and the cavity 1003 is also located inside the side cavity 1011. In this embodiment, the edge structure 1009 is located above the side cavity 1010 and has an overlapping portion with the side cavity 1010; the edge structure 1006 is located on the side cavity 1011 and has an overlapping portion with the side cavity 1011.

[0295] It should be noted that the acoustic impedance of the vacuum state or air in the side cavity 1010 is less than the acoustic impedance of the piezoelectric layer 1007, and the acoustic impedance of the vacuum state or air in the side cavity 1011 is less than the acoustic impedance of the edge structure 1006. The acoustic wave in the transverse mode is reflected at the junction of the side cavity 1010 and the piezoelectric layer 1007 and at the junction of the side cavity 1011 and the edge structure 1006, thereby blocking the leakage wave propagating towards the intermediate layer 1002 in the transverse mode and improving the Q value.

[0296] Figure 10b It is a top view structural schematic diagram of a bulk acoustic wave resonator device 1000 according to an embodiment of the present invention.

[0297] As Figure 10b shown, in this embodiment, the surrounding edge portion 1006a and the surrounding edge portion 1009a have an overlapping portion 1015 to form the surrounding edge of the resonant region 1012 and block the leakage of transverse waves. In this embodiment, the surrounding edge formed by the surrounding edge portion 1006a and the surrounding edge portion 1009a is annular. In this embodiment, the surrounding edge formed by the surrounding edge portion 1006a and the surrounding edge portion 1009a is octagonal. It should be noted that other shapes of surrounding edges known to those skilled in the art, such as hexagons, pentagons, etc., can also be applied to the embodiments of the present invention.

[0298] AsFigure 10b As shown, in this embodiment, the cavity 1003 is octagonal. It should be noted that cavities of other shapes known to those skilled in the art, such as hexagonal, pentagonal, etc., can also be applied to the embodiments of the present invention. In this embodiment, the side cavity 1010 is adjacent to the first side of the cavity 1003, and the side cavity 1011 is adjacent to the second side of the cavity 1003.

[0299] Figure 10c It is a schematic cross-sectional view of structure B of a bulk acoustic wave resonator device 1000 according to an embodiment of the present invention. Figure 10c It shows the cross-sectional view of structure B of the side cavity 1010 and the overlapping portion 1015.

[0300] Figure 11 It is a schematic cross-sectional view of structure A of a bulk acoustic wave resonator device 1100 according to an embodiment of the present invention.

[0301] As Figure 11As shown in the figure, an embodiment of the present invention provides a bulk acoustic wave resonator device 1100, which includes: a substrate 1101; an intermediate layer 1102 located on the substrate 1101, the upper surface side of the intermediate layer 1102 including a cavity 1103 and a groove 1104, wherein the groove 1104 is located on one side of the cavity 1103 and communicates with the cavity 1103, and the depth of the groove 1104 is less than the depth of the cavity 1103; an electrode layer 1105 located in the cavity 1103; an edge structure 1106 including a surrounding portion 1106a located in the cavity 1103, beside the edge of the electrode layer 1105, the electrode layer 1105 being located in the middle of the surrounding portion 1106a (i.e., the inner side, the side facing the central axis of the resonator device 1100), and an extending portion 1106b, one end of the extending portion 1106b being connected to the surrounding portion 1106a, and the other end of the extending portion 1106b being located in the groove 1104, wherein the depth of the groove 1104 is equal to the thickness of the edge structure 1106; a piezoelectric layer 1107 located on the electrode layer 1105, the edge structure 1106 and the intermediate layer 1102, covering the cavity 1103, wherein the piezoelectric layer 1107 includes a first side 1107a and a second side 1107b opposite to the first side 1107a, and the electrode layer 1105, the edge structure 1106 and the intermediate layer 1102 are located on the first side 1107a; an electrode layer 1108 located on the second side 1107b, on the piezoelectric layer 1107; an edge structure 1109 located on the second side 1107b, on the piezoelectric layer 1107, wherein the edge structure 1109 includes a surrounding portion 1109a located beside the edge of the electrode layer 1108, the electrode layer 1108 being located in the middle of the surrounding portion 1109a, and the surrounding portion 1109a coincides with the surrounding portion 1106a to form a surrounding edge; a side cavity 1110 located on the first side 1107a, between the intermediate layer 1102 and the piezoelectric layer 1107, embedded in the intermediate layer 1102 and communicating with the cavity 1103, and the side cavity 1110 contacts the piezoelectric layer 1107; and a side cavity 1111 located between the intermediate layer 1102 and the edge structure 1106, embedded in the intermediate layer 1102 and communicating with the cavity 1103; wherein the depth of the side cavity 1110 is less than the depth of the cavity 1103, and the depth of the side cavity 1111 is less than the depth of the cavity 1103.

[0302] From Figure 11It can be seen that the resonance region 1112 (i.e., the overlapping region of the electrode layer 1105 and the peripheral edge portion 1106a with the electrode layer 1108 and the peripheral edge portion 1109a) is suspended relative to the cavity 1103 and has no overlapping portion with the intermediate layer 1102, thereby blocking the leakage of acoustic waves from the horizontal edge side of the resonance region 1112 in the lateral mode into the intermediate layer 1102, and the Q value can be increased.

[0303] In this embodiment, the side cavities 1110 and 1111 are located outside the resonance region 1112 in the horizontal direction.

[0304] In this embodiment, the material of the substrate 1101 includes but is not limited to at least one of the following: silicon, silicon carbide, glass, gallium arsenide, gallium nitride, ceramics.

[0305] In this embodiment, the material of the intermediate layer 1102 includes but is not limited to at least one of the following: polymer, insulating dielectric, polysilicon. In this embodiment, the polymer includes but is not limited to at least one of the following: benzocyclobutene (i.e., BCB), photosensitive epoxy resin photoresist (e.g., SU-8), polyimide. In this embodiment, the insulating dielectric includes but is not limited to at least one of the following: aluminum nitride, silicon dioxide, silicon nitride, titanium oxide.

[0306] In this embodiment, the material of the electrode layer 1105 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, beryllium.

[0307] In this embodiment, the material of the edge structure 1106 is metal. In this embodiment, the material of the edge structure 1106 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, beryllium. In this embodiment, the material of the edge structure 1106 is the same as the material of the electrode layer 1105. In another embodiment, the material of the first edge structure under the piezoelectric layer and the material of the lower electrode layer can be different.

[0308] In this embodiment, the thickness of the edge structure 1106 is greater than the thickness of the electrode layer 1105. In another embodiment, the thickness of the first edge structure under the piezoelectric layer is less than the thickness of the lower electrode layer. In another embodiment, the thickness of the first edge structure under the piezoelectric layer is equal to the thickness of the lower electrode layer.

[0309] In this embodiment, the piezoelectric layer 1107 is a flat layer and also covers the upper surface side of the intermediate layer 1102. In this embodiment, the material of the piezoelectric layer 1107 includes but is not limited to at least one of the following: aluminum nitride, aluminum nitride alloy, gallium nitride, zinc oxide, lithium tantalate, lithium niobate, lead zirconate titanate, lead magnesium niobate - lead titanate.

[0310] In this embodiment, the piezoelectric layer 1107 includes a plurality of crystal grains, and the plurality of crystal grains include a first crystal grain and a second crystal grain. Among them, the first crystal grain and the second crystal grain are any two crystal grains among the plurality of crystal grains. Those skilled in the art know that the crystal orientation, crystal plane, etc. of crystal grains can be represented based on a coordinate system.

[0311] In this embodiment, the first crystal grain can be represented based on a first three-dimensional coordinate system, and the second crystal grain can be represented based on a second three-dimensional coordinate system. Among them, the first three-dimensional coordinate system at least includes a first coordinate axis along a first direction and a third coordinate axis along a third direction, and the second three-dimensional coordinate system at least includes a second coordinate axis along a second direction and a fourth coordinate axis along a fourth direction. Among them, the first coordinate axis corresponds to the height of the first crystal grain, and the second coordinate axis corresponds to the height of the second crystal grain.

[0312] In this embodiment, the first direction and the second direction are the same or opposite. It should be noted that the first direction and the second direction being the same means that the included angle range between the vector along the first direction and the vector along the second direction includes 0 degrees to 5 degrees; the first direction and the second direction being opposite means that the included angle range between the vector along the first direction and the vector along the second direction includes 175 degrees to 180 degrees.

[0313] In another embodiment, the first three-dimensional coordinate system is an ac three-dimensional coordinate system, where the first coordinate axis is the first c-axis and the third coordinate axis is the first a-axis; the second three-dimensional coordinate system is an ac three-dimensional coordinate system, the second coordinate axis is the second c-axis, and the fourth coordinate axis is the second a-axis. Among them, the first c-axis and the second c-axis point in the same or opposite directions.

[0314] In another embodiment, the first three-dimensional coordinate system further includes a fifth coordinate axis along a fifth direction, and the second three-dimensional coordinate system further includes a sixth coordinate axis along a sixth direction. In another embodiment, the first direction and the second direction are the same or opposite, and the third direction and the fourth direction are the same or opposite. It should be noted that the third direction and the fourth direction being the same means that the included angle range between the vector along the third direction and the vector along the fourth direction includes 0 degrees to 5 degrees; the third direction and the fourth direction being opposite means that the included angle range between the vector along the third direction and the vector along the fourth direction includes 175 degrees to 180 degrees.

[0315] In another embodiment, the first three-dimensional coordinate system is an xyz three-dimensional coordinate system, where the first coordinate axis is the first z-axis, the third coordinate axis is the first y-axis, and the fifth coordinate axis is the first x-axis; the second three-dimensional coordinate system is an xyz three-dimensional coordinate system, the second coordinate axis is the second z-axis, the fourth coordinate axis is the second y-axis, and the sixth coordinate axis is the second x-axis. In another embodiment, the first z-axis and the second z-axis point in the same direction, and the first y-axis and the second y-axis point in the same direction. In another embodiment, the first z-axis and the second z-axis point in opposite directions, and the first y-axis and the second y-axis point in opposite directions. In another embodiment, the first z-axis and the second z-axis point in the same direction, and the first y-axis and the second y-axis point in opposite directions. In another embodiment, the first z-axis and the second z-axis point in opposite directions, and the first y-axis and the second y-axis point in the same direction.

[0316] In this embodiment, the piezoelectric layer 1107 includes a plurality of grains, and the full width at half maximum of the rocking curve of the crystal formed by the plurality of grains is less than 2.5 degrees.

[0317] It should be noted that forming the piezoelectric layer 1107 on a plane can make the piezoelectric layer 1107 not include grains with obvious turning, thereby improving the electromechanical coupling coefficient of the resonant device and the Q value of the resonant device.

[0318] In this embodiment, the material of the electrode layer 1108 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, and beryllium.

[0319] In this embodiment, the part of the electrode layer 1105 that coincides with the electrode layer 1108 is located within the cavity 1103; the part of the electrode 1108 that coincides with the electrode 1105 is located above the cavity 1103.

[0320] In this embodiment, the material of the edge structure 1109 includes metal. In this embodiment, the material of the edge structure 1109 includes but is not limited to at least one of the following: molybdenum, ruthenium, tungsten, platinum, iridium, aluminum, and beryllium. In this embodiment, the material of the edge structure 1109 is the same as the material of the electrode layer 1108. In another embodiment, the material of the second edge structure on the piezoelectric layer and the material of the upper electrode layer can be different.

[0321] In this embodiment, the thickness of the edge structure 1109 is greater than the thickness of the electrode layer 1108. In another embodiment, the thickness of the second edge structure on the piezoelectric layer is less than the thickness of the upper electrode layer. In another embodiment, the thickness of the second edge structure on the piezoelectric layer is equal to the thickness of the upper electrode layer.

[0322] In this embodiment, the surrounding edge portion 1106a is located within the resonant region 1112, the surrounding edge portion 1109a is located within the resonant region 1112, and the surrounding edge portion 1106a coincides with the surrounding edge portion 1109a to form the surrounding edge of the resonant region 1112. It should be noted that the acoustic impedance of the edge portion 1113 within the resonant region 1112 is greater than the acoustic impedance of the middle portion 1114 within the resonant region 1112, and the acoustic impedance of the edge portion 1113 is greater than the acoustic impedance of the non-resonant region, so that the acoustic wave in the transverse mode is reflected at the horizontal edge of the resonant region 1112 and remains within the resonant region 1112, which can improve the Q value.

[0323] In this embodiment, the inner side of the surrounding edge portion 1106a is a straight surface, and the inner side of the surrounding edge portion 1109a is a straight surface. In another embodiment, the inner side of the surrounding edge portion may be a sloped surface.

[0324] In this embodiment, the cavity 1103 is located inside the side cavity 1110, and the cavity 1103 is also located inside the side cavity 1111. In this embodiment, the edge structure 1109 is located above the side cavity 1110 and has an overlapping portion with the side cavity 1110; the edge structure 1106 is located on the side cavity 1111 and has an overlapping portion with the side cavity 1111.

[0325] It should be noted that the acoustic impedance of the vacuum state or air in the side cavity 1110 is less than the acoustic impedance of the piezoelectric layer 1107, and the acoustic impedance of the vacuum state or air in the side cavity 1111 is less than the acoustic impedance of the edge structure 1106. The acoustic wave in the transverse mode is reflected at the junction of the side cavity 1110 and the piezoelectric layer 1107 and at the junction of the side cavity 1111 and the edge structure 1106, thereby blocking the leakage wave propagating towards the intermediate layer 1102 in the transverse mode and improving the Q value.

[0326] In summary, the bulk acoustic wave resonator device provided by the embodiment of the present invention has a relatively shallow side cavity provided outside the resonant region beside at least one side of the cavity. The acoustic impedance of the vacuum or air in the side cavity does not match the acoustic impedance of the piezoelectric layer or the electrode layer or the edge structure (i.e., the acoustic impedances are different). The transverse acoustic wave is reflected at the junction of the piezoelectric layer or the electrode layer or the edge structure and the side cavity, thereby blocking the leakage wave propagating towards the support layer (e.g., the substrate, the intermediate layer) in the transverse mode and improving the Q value.

[0327] It should be understood that the examples and embodiments here are only exemplary, and those skilled in the art can make various modifications and corrections without departing from the spirit and scope of the present invention defined by the present application and the appended claims.

Claims

1. A bulk acoustic wave resonator device, characterized in that, it includes: a first layer, the first layer including a cavity; a first electrode layer, at least one end of the first electrode layer being located within the cavity; a piezoelectric layer, located vertically on the first electrode layer and covering the cavity, the piezoelectric layer including a first side and a second side opposite to the first side along the vertical direction, the first electrode layer being located on the first side; a second electrode layer, located on the second side and vertically on the piezoelectric layer, the overlapping region of the first electrode layer, the second electrode layer and the piezoelectric layer being a first region; and at least one side cavity, located between the first layer and the piezoelectric layer, embedded in the first layer and communicating with the cavity, the depth of the at least one side cavity being less than the depth of the cavity, the at least one side cavity being located horizontally outside the first region; wherein, the at least one side cavity is used to block leaky waves propagating towards the first layer in the transverse mode; the at least one side cavity includes: a first side cavity, located horizontally outside the first region, contacting the piezoelectric layer and having an overlapping portion with the second electrode layer; the at least one side cavity includes: a second side cavity, located horizontally outside the first region, between the first layer and the first electrode layer, contacting the first electrode layer and having an overlapping portion with the first electrode layer.

2. The bulk acoustic wave resonator device according to claim 1, characterized in that, it further includes: at least one edge structure, located at the edge of the overlapping portion of the first electrode layer and the second electrode layer.

3. The bulk acoustic wave resonator device according to claim 2, characterized in that, the at least one edge structure includes: a first edge structure, located on the second side and on the second electrode layer, wherein the first edge structure includes a first surrounding portion, the first surrounding portion being located on the edge of the overlapping portion of the second electrode layer and the first electrode layer.

4. The bulk acoustic wave resonator device according to claim 3, characterized in that, the first surrounding portion is annular.

5. The bulk acoustic wave resonator device according to claim 3, characterized in that, the material of the first edge structure includes metal.

6. The bulk acoustic wave resonator device according to claim 2, characterized in that, the at least one edge structure includes: a second edge structure, the first electrode layer being located on the second edge structure, wherein the second edge structure includes a second surrounding portion, the second surrounding portion being located within the cavity and on the edge of the overlapping portion of the first electrode layer and the second electrode layer.

7. The bulk acoustic wave resonator device according to claim 6, characterized in that, the second surrounding portion is annular.

8. The bulk acoustic wave resonator device according to claim 6, characterized in that, the material of the second edge structure includes metal.

9. The bulk acoustic wave resonator device according to claim 6, characterized in that, The at least one side cavity includes: a third side cavity, which is located outside the first region along the horizontal direction, between the first layer and the second edge structure, in contact with the second edge structure, and has an overlapping portion with the second edge structure.

10. The bulk acoustic wave resonator device according to claim 2, wherein, the at least one edge structure includes: a third edge structure, which is located on the second side and on the second electrode layer. Wherein, the third edge structure includes a third surrounding portion, and the third surrounding portion is located on a partial edge of the overlapping portion of the second electrode layer and the first electrode layer.

11. The bulk acoustic wave resonator device according to claim 10, wherein, the at least one edge structure further includes: a fourth edge structure, with the first electrode layer located on the fourth edge structure. Wherein, the fourth edge structure includes a fourth surrounding portion, and the fourth surrounding portion is located within the cavity and on a partial edge of the overlapping portion of the first electrode layer and the second electrode layer.

12. The bulk acoustic wave resonator device according to claim 11, wherein, the third surrounding portion and the fourth surrounding portion partially overlap to form an annular surrounding edge.

13. The bulk acoustic wave resonator device according to claim 11, wherein, the material of the third edge structure includes metal, and the material of the fourth edge structure includes metal.

14. The bulk acoustic wave resonator device according to claim 11, wherein, the at least one side cavity includes: a fourth side cavity, which is located outside the first region along the horizontal direction, between the first layer and the fourth edge structure, in contact with the fourth edge structure, and has an overlapping portion with the fourth edge structure.

15. The bulk acoustic wave resonator device according to claim 2, wherein, the at least one edge structure includes: a fifth edge structure, which is located on the second side and on the piezoelectric layer. The fifth edge structure includes a fifth surrounding portion, the second electrode layer is located inside the fifth surrounding portion, and the fifth surrounding portion overlaps with the first electrode layer. Wherein, the overlapping portion of the second electrode layer and the first electrode layer is the second electrode layer.

16. The bulk acoustic wave resonator device according to claim 15, wherein, the fifth surrounding portion is annular.

17. The bulk acoustic wave resonator device according to claim 15, wherein, the material of the fifth edge structure includes metal.

18. The bulk acoustic wave resonator device according to claim 15, wherein, the at least one side cavity includes: a fifth side cavity, which is located outside the first region along the horizontal direction, in contact with the piezoelectric layer, and has an overlapping portion with the fifth edge structure.

19. The bulk acoustic wave resonator device according to claim 2, wherein, The at least one edge structure includes a sixth edge structure located on the first side, and the piezoelectric layer is also located on the sixth edge structure. The sixth edge structure includes a sixth surrounding portion located within the cavity. The first electrode layer is located inside the sixth surrounding portion, and the sixth surrounding portion coincides with the second electrode layer. Wherein, the overlapping portion of the first electrode layer and the second electrode layer is the first electrode layer.

20. The bulk acoustic wave resonator device according to claim 19, wherein, the sixth surrounding portion is annular.

21. The bulk acoustic wave resonator device according to claim 19, wherein, the material of the sixth edge structure includes metal.

22. The bulk acoustic wave resonator device according to claim 19, wherein, the at least one side cavity includes: a sixth side cavity located outside the first region along the horizontal direction, between the first layer and the sixth edge structure, contacting the sixth edge structure, and having an overlapping portion with the sixth edge structure.

23. The bulk acoustic wave resonator device according to claim 2, wherein, the at least one edge structure includes a seventh edge structure located on the second side and on the piezoelectric layer. The seventh edge structure includes a seventh surrounding portion located on a partial edge of the overlapping portion of the second electrode layer and the first electrode layer.

24. The bulk acoustic wave resonator device according to claim 23, wherein, the at least one side cavity includes: a seventh side cavity located outside the first region along the horizontal direction, contacting the piezoelectric layer, and having an overlapping portion with the seventh edge structure.

25. The bulk acoustic wave resonator device according to claim 23, wherein, the at least one edge structure further includes an eighth edge structure located on the first side, and the piezoelectric layer is also located on the eighth edge structure. The eighth edge structure includes an eighth surrounding portion located within the cavity and on a partial edge of the overlapping portion of the first electrode layer and the second electrode layer.

26. The bulk acoustic wave resonator device according to claim 25, wherein, the eighth surrounding portion and the seventh surrounding portion partially overlap to form an annular surrounding edge.

27. The bulk acoustic wave resonator device according to claim 25, wherein, the material of the seventh edge structure includes metal, and the material of the eighth edge structure includes metal.

28. The bulk acoustic wave resonator device according to claim 25, wherein, the at least one side cavity includes: an eighth side cavity located outside the first region along the horizontal direction, between the first layer and the eighth edge structure, contacting the eighth edge structure, and having an overlapping portion with the eighth edge structure.

29. The bulk acoustic wave resonator device according to claim 1, wherein, the first layer includes: an intermediate layer, and the intermediate layer includes the cavity. Wherein, the material of the intermediate layer includes at least one of the following: polymer, insulating dielectric, polysilicon.

30. The bulk acoustic wave resonator device according to claim 29, wherein, The at least one side cavity is located between the intermediate layer and the piezoelectric layer and is embedded in the intermediate layer.

31. A filtering device, characterized in that it includes: at least one bulk acoustic wave resonator device according to any one of claims 1 to 30.

32. A radio frequency front-end device, characterized in that it includes: a power amplification device and at least one filtering device according to claim 31; the power amplification device is connected to the filtering device.

33. A radio frequency front-end device, characterized in that it includes: a low-noise amplification device and at least one filtering device according to claim 31; the low-noise amplification device is connected to the filtering device.

34. A radio frequency front-end device, characterized in that it includes: a multiplexing device, and the multiplexing device includes at least one filtering device according to claim 31.

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