Bulk acoustic wave resonators and components, filters, and electronic devices

Abstract

The present invention relates to a bulk acoustic wave resonator, comprising: a substrate; an acoustic mirror; a bottom electrode; a top electrode; and a piezoelectric layer disposed between the bottom and top electrodes, wherein an acoustic impedance structure is disposed between the piezoelectric layer and the substrate; the acoustic impedance structure comprises a first acoustic impedance layer and a second acoustic impedance layer disposed adjacent to each other in a lateral direction, the first acoustic impedance layer and the second acoustic impedance layer having different acoustic impedances; the acoustic mirror is positioned between the first acoustic impedance layers in the lateral direction of the resonator, and the edges of the bottom and / or top electrodes are provided with protruding structures and / or recessed structures. The present invention also relates to a bulk acoustic wave resonator component, a filter, and an electronic device.

Description

Technical Field

[0001] Embodiments of the present invention relate to the field of semiconductors, and in particular to a bulk acoustic wave resonator, a filter having the resonator, a bulk acoustic wave resonator component, and an electronic device. Background Art

[0002] With the increasing development of 5G communication technology, the requirements for communication frequency bands are becoming increasingly stringent. Traditional RF filters, due to structural and performance limitations, cannot meet the requirements of high-frequency communication. Film bulk acoustic resonator (FBAR), a new type of MEMS device, offers advantages such as small size, light weight, low insertion loss, wide bandwidth, and high quality factor. It is well suited to the upgrading of wireless communication systems, making FBAR technology a research hotspot in the communications field.

[0003] The FBAR structure consists of a "sandwich" structure consisting of electrodes, piezoelectric film, and electrodes: a layer of piezoelectric material sandwiched between two metal electrode layers. A sinusoidal signal is input between the two electrodes, and the FBAR converts the input electrical signal into mechanical resonance using the inverse piezoelectric effect. The piezoelectric effect then converts the mechanical resonance into an electrical output signal. FBARs primarily utilize the longitudinal piezoelectric coefficient of the piezoelectric film to generate the piezoelectric effect, resulting in a primary operating mode of longitudinal waves in the thickness direction. This means that the acoustic waves of the FBAR are primarily confined to the film bulk of the resonator, and the primary vibration direction is longitudinal. However, due to the presence of boundaries, Lamb waves can occur at these boundaries, non-perpendicular to the piezoelectric film. These transverse Lamb waves can then leak out of the piezoelectric film, resulting in acoustic losses and a reduced Q factor of the resonator.

[0004] There are already technologies that propose to use an acoustic barrier layer to reduce transverse Lamb wave leakage, but there is still a need to further reduce transverse Lamb wave leakage. Summary of the Invention

[0005] The present invention is proposed to further reduce the leakage of the transverse Lamb wave and improve the Q value of the bulk acoustic wave resonator.

[0006] According to one aspect of an embodiment of the present invention, a bulk acoustic wave resonator is provided, comprising:

[0007] substrate;

[0008] Acoustic mirror;

[0009] bottom electrode;

[0010] a top electrode; and

[0011] A piezoelectric layer is provided between the bottom electrode and the top electrode,

[0012] in:

[0013] An acoustic impedance structure is provided between the piezoelectric layer and the substrate;

[0014] The acoustic impedance structure includes a first acoustic impedance layer and a second acoustic impedance layer arranged adjacent to each other in a lateral direction, the first acoustic impedance layer and the second acoustic impedance layer have different acoustic impedances, and the acoustic mirror is located between the first acoustic impedance layers in the lateral direction of the resonator; and

[0015] The edge portion of the bottom electrode and / or the top electrode is provided with a protruding structure and / or a concave structure.

[0016] An embodiment of the present invention further relates to a bulk acoustic wave resonator assembly, comprising at least two of the above-mentioned resonators, wherein the at least two resonators share a same substrate.

[0017] An embodiment of the present invention further relates to a filter comprising the above-mentioned bulk acoustic wave resonator or resonator assembly.

[0018] An embodiment of the present invention also relates to an electronic device, comprising the above-mentioned filter or the above-mentioned resonator or component. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The following description and accompanying drawings may better help understand these and other features and advantages of various embodiments disclosed herein, wherein like reference numerals denote like components throughout the drawings, wherein:

[0020] Figure 1 is a bottom view schematically showing a bulk acoustic wave resonator according to an exemplary embodiment of the present invention;

[0021] Figure 1A The bulk acoustic wave resonator according to an exemplary embodiment of the present invention is Figure 1 A schematic cross-sectional view taken along the MOM' line in FIG, wherein the top electrode is provided with a protruding structure and a recessed structure;

[0022] Figure 1B for Figure 1A A partial enlarged schematic diagram;

[0023] Figure 1C The bulk acoustic wave resonator according to an exemplary embodiment of the present invention is Figure 1 A schematic cross-sectional view taken along the NON' line in FIG, wherein the non-electrode connection end of the bottom electrode on the side where no release hole is provided is covered by a portion of the first acoustic impedance layer;

[0024] Figure 1D A bulk acoustic wave resonator according to another exemplary embodiment of the present invention is similar to Figure 1 A schematic cross-sectional view taken along the MOM' line in FIG, wherein only the bottom electrode is provided with a protruding structure and a recessed structure;

[0025] Figure 1E A bulk acoustic wave resonator according to another exemplary embodiment of the present invention is similar to Figure 1 A schematic cross-sectional view taken along the NON' line in FIG, wherein only the bottom electrode is provided with a protruding structure and a recessed structure;

[0026] Figure 1F A bulk acoustic wave resonator according to another exemplary embodiment of the present invention is similar to Figure 1 Schematic diagram of a cross section taken along the MOM' line in FIG, wherein both the top electrode and the bottom electrode are provided with a protruding structure and a recessed structure;

[0027] Figure 1G A bulk acoustic wave resonator according to another exemplary embodiment of the present invention is similar to Figure 1 Schematic diagram of the cross section taken along the MOM' line in FIG, wherein both the top electrode and the bottom electrode are provided with a convex structure and a concave structure, Figure 1G and Figure 1F The difference lies in the different positional relationships between the acoustic impedance layer and the non-electrode connection end of the bottom electrode;

[0028] Figure 1H A bulk acoustic wave resonator according to another exemplary embodiment of the present invention is similar to Figure 1 Schematic diagram of the cross section taken along the MOM' line in FIG, wherein both the top electrode and the bottom electrode are provided with a convex structure and a concave structure, Figure 1H and Figure 1F The difference is that in Figure 1H In the embodiment, the acoustic impedance layer covers a portion of the electrode connection end of the bottom electrode;

[0029] Figure 1I The bulk acoustic wave resonator according to an exemplary embodiment of the present invention is similar to Figure 1 A schematic cross-sectional view taken along the NON' line in FIG, wherein the non-electrode connection end of the bottom electrode on the side where the release hole is not provided is spaced apart from the first acoustic impedance layer in the lateral direction;

[0030] Figure 1J The bulk acoustic wave resonator according to an exemplary embodiment of the present invention is similar to Figure 1 Schematic diagram of the cross section taken from the MON line in FIG;

[0031] Figure 1K A bulk acoustic wave resonator according to another exemplary embodiment of the present invention is similar to Figure 1 A schematic cross-sectional view taken along the MOM' line in FIG, wherein both the top electrode and the bottom electrode are provided with a convex structure and a concave structure, wherein the convex structure and the concave structure of the top electrode extend outward relative to the convex structure and the concave structure of the bottom electrode;

[0032] Figure 1L A bulk acoustic wave resonator according to another exemplary embodiment of the present invention is similar to Figure 1 A schematic cross-sectional view taken along the MOM' line in FIG, wherein both the top electrode and the bottom electrode are provided with a convex structure and a concave structure, wherein the convex structure and the concave structure of the bottom electrode extend outward relative to the convex structure and the concave structure of the top electrode;

[0033] Figure 2 is a bottom view schematically showing a bulk acoustic wave resonator according to an exemplary embodiment of the present invention;

[0034] Figure 2A The bulk acoustic wave resonator according to an exemplary embodiment of the present invention is Figure 2 Schematic diagram of a cross section taken along the MOM' line in FIG, wherein both the top electrode and the bottom electrode are provided with cantilever and bridge structures, as well as protruding structures and recessed structures;

[0035] Figure 2B The bulk acoustic wave resonator according to an exemplary embodiment of the present invention is Figure 2 Schematic diagram of a cross section taken along the MOM' line in FIG, wherein the top electrode is provided with a cantilever and a bridge structure, as well as a protruding structure and a recessed structure;

[0036] Figure 2C for Figure 2B A partial enlarged schematic diagram in FIG, schematically showing parameters related to the cantilever and bridge structures, as well as the protrusion and recess structures of the top electrode;

[0037] Figure 2D The bulk acoustic wave resonator according to an exemplary embodiment of the present invention is Figure 2 A schematic cross-sectional view taken along the NON' line in FIG, showing the non-electrode connection ends of the bottom electrode and the top electrode, wherein the non-electrode connection end of the bottom electrode on the side where the release hole is not provided is covered by a portion of the first acoustic impedance layer;

[0038] Figure 3A A bulk acoustic wave resonator according to another exemplary embodiment of the present invention is similar to Figure 2 The MOM' line in the Figure 2C An enlarged partial cross-sectional schematic diagram of the embodiment of the present invention, wherein the bottom electrode is provided with a cantilever and a bridge structure, as well as a protruding structure and a recessed structure, and the first acoustic impedance layer does not cover the bridge structure;

[0039] Figure 3B A bulk acoustic wave resonator according to another exemplary embodiment of the present invention is similar to Figure 2 A schematic cross-sectional view taken along the NON' line in FIG, showing the non-electrode connection ends of the bottom electrode and the top electrode, and the non-electrode connection end of the bottom electrode is spaced apart from the first acoustic impedance layer;

[0040] Figure 4A A bulk acoustic wave resonator according to another exemplary embodiment of the present invention is similar to Figure 2 The MOM' line in the Figure 2C An enlarged partial cross-sectional schematic diagram;

[0041] Figure 4B A bulk acoustic wave resonator according to another exemplary embodiment of the present invention is similar to Figure 2 The MOM' line in the Figure 2C An enlarged partial cross-sectional schematic diagram of , wherein the bridge structure of the top electrode partially overlaps with the first acoustic impedance layer in the thickness direction;

[0042] Figure 4C A bulk acoustic wave resonator according to another exemplary embodiment of the present invention is similar to Figure 2 The MOM' line in the Figure 2C An enlarged partial cross-sectional schematic diagram of , wherein the bridge structure of the bottom electrode partially overlaps with the first acoustic impedance layer in the thickness direction;

[0043] Figure 5A A bulk acoustic wave resonator according to another exemplary embodiment of the present invention is similar to Figure 2 The NON' line in the Figure 2C An enlarged partial cross-sectional schematic diagram of FIG, showing that both the top electrode and the bottom electrode are provided with cantilevers and protruding structures and recessed structures;

[0044] Figure 5B A bulk acoustic wave resonator according to another exemplary embodiment of the present invention is similar to Figure 2 The MON line in the intercept is similar to Figure 2C An enlarged partial cross-sectional schematic diagram of , showing that both the top electrode and the bottom electrode are provided with cantilevers and protruding structures and recessed structures, and the bottom electrode is also provided with a bridge structure;

[0045] Figure 5C A bulk acoustic wave resonator according to another exemplary embodiment of the present invention is similar to Figure 1 The NON' line in the Figure 2C An enlarged partial cross-sectional schematic diagram showing that the non-electrode connection end of the top electrode is provided with a bridge structure, and the non-electrode connection end of the bottom electrode is provided with a cantilever structure;

[0046] Figure 6A A bulk acoustic wave resonator according to another exemplary embodiment of the present invention is similar to Figure 2 The MOM' line in the Figure 2CAn enlarged partial cross-sectional schematic diagram, wherein the inner edges of the cantilever and the bridge structure of the top electrode are respectively located outside the inner edges of the bridge structure and the cantilever of the bottom electrode;

[0047] Figure 6B A bulk acoustic wave resonator according to another exemplary embodiment of the present invention is similar to Figure 2 The MOM' line in the Figure 2C An enlarged partial cross-sectional schematic diagram, wherein the inner edges of the cantilever and the bridge structure of the top electrode are respectively located inside the inner edges of the bridge structure and the cantilever of the bottom electrode;

[0048] Figure 7 is a schematic cross-sectional view of a bulk acoustic wave resonator assembly according to an exemplary embodiment of the present invention;

[0049] Figures 8A-8O An example is shown Figure 2A The fabrication process of the structure shown;

[0050] Figure 9 A bulk acoustic wave resonator according to another exemplary embodiment of the present invention is similar to Figure 2 Schematic diagram of the cross section taken along the MOM' line. DETAILED DESCRIPTION

[0051] The technical solution of the present invention is further specifically described below through examples and in conjunction with the accompanying drawings. In the specification, the same or similar drawing numbers indicate the same or similar parts. The following description of the embodiments of the present invention with reference to the accompanying drawings is intended to explain the overall inventive concept of the present invention and should not be understood as a limitation of the present invention. Some embodiments of the invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field fall within the scope of protection of the present invention.

[0052] First, the reference numerals in the accompanying drawings of the present invention are explained as follows:

[0053] 1: The piezoelectric layer can be a single crystal piezoelectric material, such as single crystal aluminum nitride, single crystal gallium nitride, single crystal lithium niobate, single crystal lead zirconate titanate (PZT), single crystal potassium niobate, single crystal quartz film, or single crystal lithium tantalate, etc. It can also be a polycrystalline piezoelectric material (corresponding to single crystal, non-single crystal material), such as polycrystalline aluminum nitride, zinc oxide, PZT, etc., and can also be a rare earth element doped with a certain atomic ratio of the above materials The material, for example, can be doped aluminum nitride, which contains at least one rare earth element, such as scandium (Sc), yttrium (Y), magnesium (Mg), titanium (Ti), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), etc.

[0054] 2: Bottom electrode, the material can be molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or a composite of the above metals or their alloys.

[0055] 3: Acoustic impedance layer 1 or the first acoustic impedance layer, the material can be aluminum nitride, silicon dioxide, silicon nitride, polysilicon, amorphous silicon.

[0056] 4: Acoustic impedance layer 2 or the second acoustic impedance layer, which also serves as a sacrificial layer. The second acoustic impedance layer can be made of silicon dioxide, doped silicon dioxide, polycrystalline silicon, amorphous silicon, etc., but it is different from the first acoustic impedance layer material. The etchant for the second acoustic impedance layer is not easy to etch or does not etch the first acoustic impedance layer material.

[0057] 5: Substrate, optional materials include single crystal silicon, gallium nitride, gallium arsenide, sapphire, quartz, silicon carbide, diamond, etc.

[0058] 5a: Auxiliary substrate, the optional materials are single crystal silicon, gallium nitride, gallium arsenide, sapphire, quartz, silicon carbide, diamond, etc., and can also be single crystal piezoelectric substrates such as lithium niobate, lithium tantalate, potassium niobate, etc.

[0059] 6: Top electrode, which can be made of the same material as the bottom electrode. The materials can be molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, or a composite or alloy of the above metals. The top and bottom electrodes are generally made of the same material, but can also be different.

[0060] 6a: Electrode connection part 1 (or electrode lead part), which can be made at the same time as the top electrode. The material can be molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or a composite of the above metals or their alloys.

[0061] 7: Electrode connection part 2 (Bonding PAD, or bottom electrode electrical connection layer), the material can be copper, gold or a composite of the above metals or their alloys.

[0062] 8: Acoustic mirror, which can be a cavity, a Bragg reflector layer or other equivalent forms. In the embodiment shown in the present invention, a cavity is used.

[0063] 9: Release hole, which is used to etch the sacrificial layer to form a cavity.

[0064] 9a: Electrode opening or via, which can be made at the same time as the release hole, and is used to electrically connect the electrode connection portion 1 with the electrode connection end of the bottom electrode.

[0065] 10: Cantilevered wing.

[0066] 11: The raised structure can be made of molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or a composite of the above metals or their alloys, or a dielectric material or piezoelectric material such as silicon dioxide, silicon nitride, aluminum nitride, etc.

[0067] 12: Recessed structure, a recess formed by structure 12A.

[0068] 12A: Recessed structure: The material may be molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or a composite of the above metals or an alloy thereof, or a dielectric material or piezoelectric material such as silicon dioxide, silicon nitride, aluminum nitride, etc.

[0069] 13: Bridge structure.

[0070] Figure 1 FIG1A is a bottom view of a BAW resonator according to an exemplary embodiment of the present invention. FIG1A is a bottom view of a BAW resonator according to an exemplary embodiment of the present invention. Figure 1 A schematic cross-sectional view taken along the MOM' line in FIG, showing the electrode lead-out region of the top electrode, with the electrode connection end of the bottom electrode covered by a portion of the first acoustic impedance layer, and the non-electrode connection end of the bottom electrode spaced apart from the first acoustic impedance layer in the lateral direction.

[0071] Figure 1B for Figure 1A A partial enlarged schematic diagram. Figure 1C The bulk acoustic wave resonator according to an exemplary embodiment of the present invention is Figure 1 The non-electrode connection end of the bottom electrode on the side where no release hole is provided is covered by a portion of the first acoustic impedance layer.

[0072] like Figure 1 、 Figures 1A-1CAs shown, the BAW resonator includes: a substrate 5; an acoustic mirror 8; a bottom electrode 2; a top electrode 6; and a single crystal piezoelectric layer 1 disposed between the bottom and top electrodes. An acoustic impedance structure is disposed between the piezoelectric layer 1 and the substrate 5. The acoustic mirror 8 is positioned between the acoustic impedance structure in the lateral direction of the resonator. The acoustic impedance structure includes a first acoustic impedance layer 3 and a second acoustic impedance layer 4 disposed adjacent to each other in the lateral direction. More specifically, the acoustic mirror 8 is positioned between the first acoustic impedance layer 3 in the lateral direction of the resonator.

[0073] like Figure 1B As shown, for the protruding structure 11, its width at the non-electrode connection end is d21a, and its width at the electrode connection end is d22a.

[0074] like Figure 1B As shown, the width of the recessed structure on the non-electrode connection end side is d51a, and the width of the recessed structure on the electrode connection end side is d52a.

[0075] like Figure 1B As shown, the recess-forming structure 12A forms a recessed structure between itself and the protruding structure.

[0076] exist Figure 1B In the embodiment, the top electrode is provided with both a convex structure 11 and a concave structure 12. The present invention is not limited thereto, and the convex structure and the concave structure may be provided only on the top electrode, such as Figure 1B As shown; it is also possible to set the protrusion structure and the recessed structure only on the bottom electrode, as mentioned later Figures 1D-1E As shown; the top electrode and the bottom electrode may also be provided with a convex structure and a concave structure, as mentioned later Figures 1F-1L As shown, in addition, only convex structures or concave structures may be provided on the top electrode and / or the bottom electrode, and convex structures or concave structures may be provided on part of the sides of the resonator polygon.

[0077] In the present invention, the first acoustic impedance layer 3 and the second acoustic impedance layer 4 have different acoustic impedances, creating an impedance mismatch, which continuously reflects sound waves and forms a reflective structure for transverse sound waves. This prevents transverse sound wave leakage, helps lock energy within the resonator, and thus improves the Q value. The first acoustic impedance layer 3 and the second acoustic impedance layer 4 serve as the first acoustic reflection layer and the second acoustic reflection layer, forming an effective acoustic impedance mismatch layer that can prevent the leakage of transverse sound waves. By setting the width of the first acoustic impedance layer 3 and the second acoustic impedance layer 4, the leakage of transverse waves can be suppressed. This structure primarily reflects transverse waves that leak outside the resonator back into the resonator, thereby improving the Q value.

[0078] If there is only an external acoustic reflection structure formed by the first acoustic impedance layer 3 and the second acoustic impedance layer 4, the shear waves reflected by the first acoustic impedance layer 3 and the second acoustic impedance layer 4 to the inside of the resonator will still have some energy leaking from the boundary because there is no restriction of the boundary structure, so it is necessary to lock this part of the energy inside the resonator. In the present invention, because after the convex structure and the concave structure are introduced into the electrode, the equivalent acoustic impedance of the corresponding interval of the convex structure and the concave structure is different from the equivalent acoustic impedance of the original resonator stacking thickness due to the change in the stacking thickness, thereby forming an impedance mismatch interface, which can not only prevent the leakage of internal shear waves but also further lock the energy reflected by the first acoustic impedance layer 3 and the second acoustic impedance layer 4 inside the resonator, so it can further effectively prevent energy leakage. The mutual cooperation of the acoustic impedance structure, the convex structure and the concave structure can effectively prevent the leakage of sound waves and improve the Q value of the resonator.

[0079] In the present invention, single crystal piezoelectric material is used, which can reduce piezoelectric loss, thereby obtaining a higher resonator Q value, and at the same time can improve the electromechanical coupling coefficient and power capacity.

[0080] In a further embodiment, the widths of the portions of the first acoustic impedance layer 3 and the second acoustic impedance layer 4 in contact with the piezoelectric layer 1 are mλ1 / 4 and nλ2 / 4, respectively, where m and n are both odd numbers, such as 1, 3, 5, 7, etc., and λ1 and λ2 are the wavelengths of acoustic waves propagating laterally at the resonant frequency at the portions of the first and second acoustic impedance layers in contact with the piezoelectric layer. The resonant frequency is a frequency within the resonant range of the resonator, which can be the series resonant frequency or the parallel resonant frequency of the resonator, a frequency between the series and parallel resonant frequencies, or a frequency slightly below the series resonant frequency or slightly above the parallel resonant frequency. In the accompanying drawings, the width of the first acoustic impedance layer 3 is represented by A, while the width of the second acoustic impedance layer 4 is represented by B. Selecting these widths facilitates effective acoustic impedance mismatching, prevents lateral acoustic wave leakage, and further improves the Q value of the resonator. m and n can be the same or different, and remain within the scope of protection of the present invention.

[0081] The materials forming the first acoustic impedance layer 3 include aluminum nitride, silicon dioxide, silicon nitride, polycrystalline silicon, and amorphous silicon. The materials forming the second acoustic impedance layer 4 include silicon dioxide, doped silicon dioxide, polycrystalline silicon, and amorphous silicon. The materials of the first acoustic impedance layer 3 and the second acoustic impedance layer 4 are different. Optionally, the material forming the first acoustic impedance layer 3 includes silicon dioxide, and the material forming the second acoustic impedance layer 4 includes polycrystalline silicon. Alternatively, the material forming the first acoustic impedance layer 3 includes silicon nitride or aluminum nitride, and the material forming the second acoustic impedance layer 4 includes silicon dioxide or doped silicon dioxide. In the present invention, to increase the degree of acoustic mismatch at the junction of the first acoustic impedance layer 3 and the second acoustic impedance layer 4, the difference in acoustic impedance between the two layers can be selected to be as large as possible.

[0082] Please refer to the attached Figures 8A-8O As described above, during the process of manufacturing the resonator, the second acoustic impedance layer is also used as a sacrificial layer. Therefore, when releasing the sacrificial layer, it is necessary to select a suitable releasing etchant so that the etchant only etches the first acoustic impedance material and does not etch or etches a very small amount of the second acoustic impedance material.

[0083] For example, Figure 1A As shown, the non-electrode connection end of the bottom electrode 2 ( Figure 1A The end face of the bottom electrode 2 (right end) is separated from the first acoustic impedance layer 3 in the acoustic impedance structure in the lateral direction, so that the sound wave is also totally reflected at the lateral interface between the non-electrode connection end of the bottom electrode and the gap, thereby reducing the leakage of the sound wave. Based on the gap structure at the non-electrode connection end, the lateral sound wave leakage can be further prevented and the Q value of the resonator can be improved. On the other hand, the non-electrode connection end of the bottom electrode 2 ( Figure 1A and 2A If the end face of the top electrode (the right end in FIG) is covered by the first acoustic impedance layer 3, a parasitic capacitance will be formed with the portion of the top electrode outside the cavity, thereby affecting the electromechanical coupling coefficient of the resonator.

[0084] In an alternative embodiment, in a longitudinal section of the resonator through the electrode connection end of the bottom electrode 2 (eg Figure 1A In the cross-sectional view shown in FIG, the end surface of the non-electrode connection end of the bottom electrode 2 is spaced apart from the acoustic impedance structure by a distance C (corresponding to Figure 1B The distance d44b) is in the range of 0.5 μm to 10 μm. In addition to the end values, the distance may also be, for example, 3 μm, 5 μm, 7 μm, etc.

[0085] In e.g. Figure 1AIn the illustrated embodiment, the bottom electrode 2 is wrapped on one side of the electrode connection end by a continuous reflective layer or acoustic impedance structure formed by the first acoustic impedance layer 3 and the second acoustic impedance layer 4. More specifically, it is covered by the first acoustic impedance layer 3. On the one hand, this structure is conducive to improving the mechanical stability of the resonator and more easily conducts the heat generated during operation of the resonator to the substrate through the electrode and the first acoustic impedance layer 3, thereby improving the power capacity of the resonator. On the other hand, although energy will leak from the end surface of the bottom electrode into the first acoustic impedance layer 3, due to the presence of the reflective interface formed by the second acoustic impedance layer and the first acoustic impedance layer, it is conducive to locking as much energy as possible inside the resonator, so that the resonator maintains a high Q value.

[0086] In an optional embodiment, the end surface of the non-electrode connection end and the end surface of the electrode connection end of the bottom electrode 2 can be spaced apart from the first acoustic impedance layer 3 in the lateral direction, so that the sound wave is also totally reflected at the lateral interface between the bottom electrode and the gap, thereby reducing the leakage of the sound wave and improving the Q value of the resonator. Figure 1A The structure shown in the figure also has a gap at the electrode connection end, which helps further prevent lateral acoustic wave leakage. However, because the bottom electrode and the first acoustic impedance layer are not in direct contact, heat must be indirectly conducted to the first acoustic impedance layer and the substrate through the piezoelectric material, resulting in poor power handling. Similarly, the distance between the end face of the electrode connection end and the acoustic impedance structure in the lateral direction can be C, or a value different from C.

[0087] exist Figure 1B In this figure, d21a represents the width of the raised structure 11 of the top electrode at the non-electrode connection end; d22a represents the width of the raised structure 11 of the top electrode at the electrode connection end; d51a represents the width of the recessed structure 12 of the top electrode at the non-electrode connection end; d52a represents the width of the recessed structure 12 of the top electrode at the electrode connection end; d44a represents the lateral distance between the non-electrode connection end of the top electrode and the first acoustic impedance layer 3; and d44b represents the lateral distance between the non-electrode connection end of the bottom electrode and the first acoustic impedance layer 3. In this case, the non-electrode connection end of the bottom electrode falls within the raised structure of the top electrode connection end, meaning that the non-electrode connection end of the bottom electrode partially overlaps the raised structure of the electrode connection end of the top electrode, with a distance of d61b. Furthermore, the distance from the outer edge of the raised structure of the electrode connection end of the top electrode to the edge of the first acoustic impedance layer 3 is d411a, which can be greater than 0, meaning that the outer edge of the raised structure of the electrode connection end of the top electrode can be projected onto the inner side of the first acoustic impedance layer 3 below it. However, the present invention is not limited thereto, and the distance (d411a) may also be a negative value, that is, the protruding structure of the electrode connection end of the top electrode may also partially overlap with the first acoustic impedance layer 3 thereunder.

[0088] In an optional embodiment, d21a is within the range of 0–50 μm; and / or d22a is within the range of 0–50 μm; and / or d51a is within the range of 0–50 μm; and / or d52a is within the range of 0–50 μm; and / or d44a is within the range of 0–50 μm; and / or d44b is within the range of 0–50 μm; and / or d61b is within the range of 0–50 μm; and / or d411a is within the range of 0–50 μm. In an optional embodiment, d21a, d44a, d61b, d22a-d61b, and d411a may be an odd multiple of λ / 4, where λ is the wavelength of acoustic waves propagating laterally at the resonant frequency of the stacked structure at each distance in the thickness direction of the corresponding region. In the specific example, the intervals d21a and d61b correspond to the top electrode, bottom electrode, piezoelectric layer and raised structure, the interval d44a corresponds to the bottom electrode and piezoelectric layer, the interval d22a-d61b corresponds to the piezoelectric layer, top electrode and raised structure, and the interval d411a corresponds to the top electrode and piezoelectric layer.

[0089] exist Figure 1C In the figure, the non-electrode connection ends of the bottom electrode and the top electrode are shown, and the non-electrode connection end of the bottom electrode 2 on the side where the release hole is not set is covered by a part of the first acoustic impedance layer 3, and the width of the covered area is equal to the lateral distance d44b between the non-electrode connection end of the bottom electrode and the first acoustic impedance layer 3. On the one hand, this structure is conducive to improving the mechanical stability of the resonator, and it is easier to conduct the heat generated when the resonator is working to the substrate through the electrode and the first acoustic impedance layer 3, thereby improving the power capacity of the resonator; on the other hand, although energy will leak from the end surface of the bottom electrode to the first acoustic impedance layer 3 in this structure, due to the presence of the reflection interface formed by the second acoustic impedance layer and the first acoustic impedance layer, it is conducive to locking as much energy as possible inside the resonator, so that the resonator maintains a high Q value. In addition, along Figure 1 In the cross section taken by the NON' line in , the first acoustic impedance layer 3 can also be separated from the non-electrode connection end of the bottom electrode, so that the sound wave is totally reflected at the lateral interface between the bottom electrode and the gap, thereby reducing the leakage of the sound wave and improving the Q value of the resonator.

[0090] like Figure 1C As shown, the non-electrode connection end of the bottom electrode 2 is a non-protruding structure, and in the lateral direction of the resonator, a release hole 9 (on the right) can be provided between the outer edge of the non-electrode connection end and the first acoustic impedance layer 3.

[0091] In alternative embodiments, d21a is within the range of 0–50 μm; and / or d44a is within the range of 0–50 μm; and / or d44b is within the range of 0–50 μm.

[0092] In an optional embodiment, d21a, d44a, and d44b may be odd multiples of λ / 4, where λ is the wavelength of acoustic waves propagating laterally in the stacked structure at the resonant frequency in the thickness direction of the corresponding region at each distance. Specifically, the interval d21a corresponds to the top electrode, bottom electrode, piezoelectric layer, and raised structure; the interval d44a corresponds to the bottom electrode and piezoelectric layer; and the interval d44b corresponds to the first acoustic impedance layer, bottom electrode, and piezoelectric layer.

[0093] Figure 1D A bulk acoustic wave resonator according to another exemplary embodiment of the present invention is similar to Figure 1 Schematic cross-sectional view taken along line MOM' in FIG. 1 , wherein only the bottom electrode is provided with a protruding structure 11 and a recessed structure 12A.

[0094] exist Figure 1D In the figure, for the protruding structure 11, its width at the non-electrode connection end is d21b, and its width at the electrode connection end is d22b.

[0095] like Figure 1D As shown, the width of the recessed structure on the non-electrode connection end side is d51b, and the width of the recessed structure on the electrode connection end side is d52b.

[0096] like Figure 1D As shown, the recess-forming structure 12A forms a recessed structure between itself and the protruding structure.

[0097] like Figure 1D As shown, the first acoustic impedance layer (corresponding to A) and the raised structure 11 of the electrode connection end of the bottom electrode 2 are separated from each other in the lateral direction by a distance d411b; the non-electrode connection end of the bottom electrode is separated from the first acoustic impedance layer in the lateral direction by a distance d44b; the non-electrode connection end of the top electrode is separated from the first acoustic impedance layer 3 in the lateral direction by a distance d44a; the non-electrode connection end of the top electrode partially overlaps with the raised structure of the bottom electrode connection end, and the distance is d61a. Among them, d411b can be greater than 0, that is, the outer edge of the raised structure of the electrode connection end of the bottom electrode falls on the inner side of the first acoustic impedance layer 3. However, the present invention is not limited to this, and the distance can also be a negative value, that is, the raised structure of the electrode connection end of the bottom electrode can also partially overlap with the first acoustic impedance layer 3. In this case, it is also necessary to ensure that d44a is greater than 0, that is, the non-electrode connection end of the top electrode on the corresponding side falls on the inner side of the first acoustic impedance layer 3, that is, there is no overlap between the two.

[0098] In optional embodiments, d21b is in the range of 0–50 μm; and / or d22b is in the range of 0–50 μm; and / or d51a is in the range of 0–50 μm; and / or d52a is in the range of 0–50 μm; and / or d44a is in the range of 0–50 μm; and / or d44b is in the range of 0–50 μm; and / or d61a is in the range of 0–50 μm; and / or d411b is in the range of 0–50 μm.

[0099] In an optional embodiment, d21b, d44b, d61a, d22b-d61a, and d411b may be odd multiples of λ / 4, where λ is the wavelength of acoustic waves propagating laterally at the resonant frequency of the stacked structure in the thickness direction of each distance corresponding to the region. Specifically, the intervals d21b and d61a correspond to the top electrode, bottom electrode, piezoelectric layer, and raised structure portion; the interval d44b corresponds to the top electrode and piezoelectric layer portion; the interval d22b-d61a corresponds to the piezoelectric layer, bottom electrode, and raised structure portion; and the interval d411b corresponds to the bottom electrode and piezoelectric layer portion.

[0100] Figure 1E A bulk acoustic wave resonator according to another exemplary embodiment of the present invention is similar to Figure 1 Schematic cross-sectional view taken along line NON' in FIG. 1 , wherein only the bottom electrode is provided with the protruding structure 11 and the recessed structure 12 .

[0101] It should be pointed out that in the present invention, for the parameters or marks shown in the figures, the same marks have the same or similar meanings. Accordingly, the descriptions of these parameters or marks are also applicable to the descriptions of these parameters in other embodiments and will not be repeated here.

[0102] like Figure 1E As shown, the non-electrode connection end of the top electrode is a non-convex structure, and in the lateral direction of the resonator, a release hole 9 (on the right) can be provided between the outer edge of the non-electrode connection end and the first acoustic impedance layer 3. Figure 1E In the figure, d44a represents the distance from the non-electrode connection end of the top electrode to the first acoustic impedance layer in the lateral direction on the side where the release hole 9 is not provided, and d44b represents the distance from the non-electrode connection end of the bottom electrode to the first acoustic impedance layer in the lateral direction on the side where the release hole 9 is not provided. In this case, the non-electrode connection end of the top electrode at least partially overlaps with the bottom electrode protrusion structure, that is, the non-electrode connection end of the top electrode can fall on the inner side of the bottom electrode protrusion structure (that is, between the inner and outer edges of the protrusion structure), can be aligned with the outer edge of the bottom electrode protrusion structure, or can fall on the outer side of the outer edge of the bottom electrode protrusion structure. Furthermore, the non-electrode connection end of the top electrode can also partially overlap with the first acoustic impedance layer 3 corresponding thereto.

[0103] In addition, the protruding structure of the non-electrode connection end of the bottom electrode can not only Figure 1E As shown, it is completely arranged in the cavity and can also extend outward to partially overlap with the first acoustic impedance layer, and the non-electrode connection end of the top electrode does not overlap with the first acoustic impedance layer, that is, the non-electrode connection end of the top electrode falls on the inner side of the edge of the first acoustic impedance layer.

[0104] Figure 1F A bulk acoustic wave resonator according to another exemplary embodiment of the present invention is similar to Figure 1 The cross-sectional diagram of the MOM' line in FIG, wherein both the top electrode and the bottom electrode are provided with a convex structure and a concave structure. At this time, the outer edge of the convex structure of the non-connecting end of the top electrode should be inside the outer edge of the convex structure of the corresponding bottom electrode connecting end, and the outer edge of the convex structure of the non-connecting end of the bottom electrode should be inside the outer edge of the convex structure of the corresponding top electrode connecting end. That is, when the inner edges of the convex structures of the top electrode and the bottom electrode are aligned, d21a is smaller than d22b, and d21b is smaller than d22a. Figures 1G-1H The same requirements apply.

[0105] Figure 1G A bulk acoustic wave resonator according to another exemplary embodiment of the present invention is similar to Figure 1 Schematic diagram of a cross section taken along the MOM' line in FIG, wherein both the top electrode and the bottom electrode are provided with a protruding structure and a recessed structure.

[0106] Figure 1G and Figure 1F The difference is that in Figure 1G In the embodiment, the first acoustic impedance layer 3 has an overlapping area with the protruding structure of the electrode connection end of the top electrode in the lateral direction, and the width of the overlapping area is d411a. Figure 1F In the embodiment, the first acoustic impedance layer 3 is spaced apart from the protruding structure of the electrode connection end of the top electrode in the lateral direction.

[0107] Figure 1H A bulk acoustic wave resonator according to another exemplary embodiment of the present invention is similar to Figure 1 Schematic diagram of a cross section taken along the MOM' line in FIG, wherein both the top electrode and the bottom electrode are provided with a protruding structure and a recessed structure.

[0108] Figure 1H and Figure 1F The difference is that in Figure 1H In the figure, the first acoustic impedance layer A covers a portion of the raised structure of the electrode connection end of the bottom electrode. The width of the covered portion is d411b. At this time, d44a is greater than 0, that is, the outer edge of the raised structure of the non-electrode connection end of the corresponding top electrode is inside the first acoustic impedance layer (the two have no overlapping parts). Figure 1FIn the embodiment, the first acoustic impedance layer is spaced apart from the protruding structure of the electrode connecting end of the bottom electrode in a lateral direction.

[0109] Figure 1I The bulk acoustic wave resonator according to an exemplary embodiment of the present invention is similar to Figure 1 The cross-sectional schematic diagram is taken along the NON' line in FIG, and the non-electrode connection end of the bottom electrode on the side where the release hole is not provided is spaced apart from the first acoustic impedance layer in the lateral direction, that is, Figure 1I The d44b shown in is greater than 0. At this time, the raised structure at the non-electrode connection end of the top electrode and the raised structure at the non-electrically connected bottom electrode at least partially overlap, that is, the outer edge of the raised structure at the non-electrode connection end of the top electrode can fall on the inner side of the raised structure of the bottom electrode (that is, between the inner and outer edges of the raised structure of the bottom electrode), or can be aligned with the outer edge of the raised structure of the bottom electrode, or can fall on the outer side of the outer edge of the raised structure of the bottom electrode. Furthermore, the raised structure at the non-electrode connection end of the top electrode can also partially overlap with the first acoustic impedance layer 3 corresponding thereto.

[0110] Figure 1J The bulk acoustic wave resonator according to an exemplary embodiment of the present invention is similar to Figure 1 Schematic diagram of the cross section taken along the NON' line in FIG. At this time, the non-electrode connection end of the bottom electrode on the side where the release hole is not provided partially overlaps with the first acoustic impedance layer. At this time, it is also necessary to ensure that the protruding structure of the non-electrode connection end of the top electrode does not overlap with the first acoustic impedance layer, that is, Figure 1J The d44a shown in is greater than 0.

[0111] Figure 1K A bulk acoustic wave resonator according to another exemplary embodiment of the present invention is similar to Figure 1 Schematic diagram of a cross-section taken along the MOM' line in FIG, wherein both the top electrode and the bottom electrode are provided with a convex structure and a concave structure, wherein the convex structure and the concave structure of the top electrode extend outward relative to the convex structure and the concave structure of the bottom electrode.

[0112] Figure 1L A bulk acoustic wave resonator according to another exemplary embodiment of the present invention is similar to Figure 1 Schematic cross-sectional view taken along the MOM' line in FIG, wherein both the top electrode and the bottom electrode are provided with a convex structure and a concave structure, wherein the convex structure and the concave structure of the bottom electrode extend outward relative to the convex structure and the concave structure of the top electrode.

[0113] exist Figure 1K and 1LIn the figure, Δd1 represents the distance in the lateral direction between the inner edge of the cantilever at the non-electrode connection end of the top electrode and the inner edge of the bridge structure at the electrode connection end of the bottom electrode; Δd6 represents the distance in the lateral direction between the inner edge of the raised structure at the electrode connection end of the top electrode and the inner edge of the raised structure at the non-electrode connection end of the bottom electrode; Δd3 represents the distance in the lateral direction between the inner edge of the recessed structure at the non-electrode connection end of the top electrode and the inner edge of the recessed structure at the electrode connection end of the bottom electrode; and Δd4 represents the distance in the lateral direction between the inner edge of the recessed structure at the electrode connection end of the top electrode and the inner edge of the recessed structure at the non-electrode connection end of the bottom electrode. Not shown in the figure, the inner edge of the raised structure at the non-electrode connection end of the top electrode and the inner edge of the raised structure at the non-electrode connection end of the bottom electrode may also be spaced apart. Furthermore, the offset distance between the inner edges of the raised structures of the top and bottom electrodes on each side of the resonator can be the same or different. In an optional embodiment, Δd1, Δd3, Δd4, and Δd6 are in the range of 0–20 μm.

[0114] By staggering the inner edge positions of the raised structures of the top electrode and the bottom electrode, on the one hand, the impedance mismatch interface can be further increased in the lateral direction of the resonator, the reflection characteristics of the transverse wave can be improved, and the Q value of the resonator can be further improved. On the other hand, the intra-chip heterogeneity caused by process errors can be reduced, thereby improving the device yield in the entire wafer. In the present invention, for the raised structure or recessed structure on the top electrode, its width can be the same or different from the raised structure or recessed structure on the bottom electrode. For the raised structure or recessed structure on the top electrode and / or the bottom electrode, the width of the raised structure or recessed structure corresponding to different sides of the same resonator polygon can be the same or different, all within the scope of protection of the present invention.

[0115] exist Figure 1 as well as Figures 1A-1L In the embodiment shown, the top electrode and / or the bottom electrode are provided with a convex structure and a concave structure, however, the boundary structure of the electrode is not limited thereto, and a cantilever and a bridge structure may also be provided. Figure 2-6B Further specific explanation.

[0116] Figure 2 FIG. 1 is a bottom view of a BAW resonator according to an exemplary embodiment of the present invention, showing a boundary structure except for the protruding structure and the recessed structure.

[0117] Figure 2A The bulk acoustic wave resonator according to an exemplary embodiment of the present invention is Figure 1Schematic cross-sectional view taken along the MOM' line in FIG, showing the electrode lead-out region of the bottom electrode and the electrode lead-out region of the top electrode, wherein the electrode connection end of the bottom electrode is covered by a portion of the first acoustic impedance layer, and the non-electrode connection end of the bottom electrode is spaced apart from the first acoustic impedance layer in the lateral direction.

[0118] exist Figure 2A In the embodiment, both the top and bottom electrodes are provided with cantilevers 10 and bridge structures 13, as well as protruding structures 11 and recessed structures 12. In this embodiment, the introduction of cantilevers and bridge structures, as well as protruding structures and recessed structures into the electrodes, can prevent the leakage of internal shear waves and further lock the energy reflected by the first acoustic impedance layer 3 and the second acoustic impedance layer 4 within the resonator, thereby further effectively preventing energy leakage. The interaction between the acoustic impedance structure, the cantilevers and bridge structures, and the protruding structures and recessed structures can effectively prevent the leakage of sound waves and improve the Q value of the resonator.

[0119] Figure 2B The bulk acoustic wave resonator according to an exemplary embodiment of the present invention is Figure 2 Schematic diagram of a cross section taken along the MOM' line in FIG, wherein the top electrode is provided with a cantilever and a bridge structure, as well as a protruding structure and a recessed structure; Figure 2C for Figure 2B The locally enlarged schematic diagram in FIG. 1 schematically shows parameters related to the cantilever and bridge structures of the top electrode, as well as the protrusion structure and the recessed structure.

[0120] exist Figure 2C , d12a represents the width of the bridge structure of the top electrode, and d11a represents the width of the cantilever of the top electrode.

[0121] exist Figure 2C In the embodiment, the non-electrode connection end of the bottom electrode 2 is a non-cantilever structure ( Figure 2C The non-electrode connection end has no cantilever, i.e., a non-cantilever structure).

[0122] like Figure 2C As shown, the overlap area between the non-electrode connection end of the bottom electrode and the bridge structure of the top electrode in the thickness direction of the resonator (or the lateral distance between the inner edge of the bridge structure and the endpoint of the corresponding non-electrode connection end) is d43a, and its value has a significant impact on the resonator performance. The width of the overlap area d43a can be in the range of 0–20 μm to ensure that the non-electrode connection end of the bottom electrode falls within the projection of the bridge structure of the top electrode.

[0123] exist Figure 2C In the case of the top electrode, the non-electrode connection end ( Figure 2CThe lateral distance between the outer edge of the cantilever (representing the top electrode) and the first acoustic impedance layer 3 is d40a, and the lateral distance between the non-electrode connection end of the bottom electrode and the first acoustic impedance layer 3 is d44b. The lateral distance between the outer edge of the bridge structure of the top electrode and the first acoustic impedance layer 3 is d41a. Because the first acoustic impedance layer 3 reflects shear waves that leak out of the filter, and its distance plays a significant role in wave and energy reflection, the setting or selection of d40a, d41a, and d44b significantly influences the performance of the resonator. In optional embodiments, d40a is within the range of 0–50 μm; and / or d44b is within the range of 0–50 μm; and / or d41a is within the range of 0–50 μm.

[0124] In addition, d41a and d44b can also be negative values. When d41a is negative and d44b is positive, the outer edge of the top electrode bridge structure crosses the first acoustic impedance layer 3, and the first acoustic impedance layer 3 is spaced apart from the non-connected end of the bottom electrode.

[0125] When both d41a and d44b are negative, the first acoustic impedance layer 3 covers the non-connected end of the bottom electrode. To prevent the portion of the bottom electrode extending into the acoustic impedance layer from forming parasitic capacitance with the electrode connection end of the top electrode, thereby reducing the resonator's electrical performance (including Q and electromechanical coupling coefficient), the inner end of the bridge structure must span the edge of the first acoustic impedance layer 3, while the outer end must span the edge of the non-connected end of the bottom electrode. This ensures that the absolute value of d41a is less than d12a, and that d43a is also less than d12a. This improves the mechanical stability of the resonator and more easily conducts heat generated during operation of the resonator to the substrate through the electrode and the first acoustic impedance layer 3, thereby increasing the power capacity of the resonator. Furthermore, although energy may leak from the end surface of the bottom electrode into the first acoustic impedance layer 3, the presence of a reflective interface formed by the second acoustic impedance layer and the first acoustic impedance layer allows for as much energy as possible to be locked within the resonator, maintaining a high Q value.

[0126] like Figure 2C As shown, the outer edge of the cantilever of the top electrode 6 is located inside the edge of the first acoustic impedance layer 3, that is, d40a is greater than 0 as shown in the figure. In addition, the outer edge of the cantilever of the top electrode 6 can also cross the edge of the first acoustic impedance layer 3, that is, d40a is less than 0 as shown in the figure. However, it is necessary to ensure that the inner edge of the cantilever of the top electrode 6 is always inside the edge of the first acoustic impedance layer 3.

[0127] Figure 2D The bulk acoustic wave resonator according to an exemplary embodiment of the present invention is Figure 2A schematic cross-sectional view taken along line NON' in FIG. 1 shows the non-electrode connection ends of the bottom and top electrodes. The non-electrode connection end of the bottom electrode 2 on the side without the release hole is covered by a portion of the first acoustic impedance layer 3. The width of the covered area is equal to the lateral distance d44b between the non-electrode connection end of the bottom electrode and the first acoustic impedance layer 3.

[0128] The non-electrode connection end of the bottom electrode 2 on the side where the release hole is not provided is covered by a portion of the first acoustic impedance layer 3. On the one hand, this structure is conducive to improving the mechanical stability of the resonator, and it is easier to conduct the heat generated when the resonator is working to the substrate through the electrode and the first acoustic impedance layer 3, thereby improving the power capacity of the resonator; on the other hand, although energy will leak from the end surface of the bottom electrode into the first acoustic impedance layer 3 in this structure, due to the existence of the reflection interface formed by the second acoustic impedance layer and the first acoustic impedance layer, it is conducive to locking as much energy as possible inside the resonator, so that the resonator maintains a high Q value.

[0129] like Figure 2D As shown, the non-electrode connection end of the bottom electrode 2 is a non-cantilever structure, and in the lateral direction of the resonator, a release hole 9 (right side) can be provided between the outer edge of the non-electrode connection end and the first acoustic impedance layer 3. At the position where the release hole 9 is provided, the outer edge of the cantilever of the top electrode ( Figure 2D The distance between the non-electrode connection end of the bottom electrode (on the right side) is d49a, and d49a is equal to the sum of d44b and d40a.

[0130] In alternative embodiments, d11a is within the range of 0–50 μm; and / or d21a is within the range of 0–50 μm; d40a is within the range of 0–50 μm; and / or d44b is within the range of 0–50 μm.

[0131] In an optional embodiment, d21a, d11a, d40a, and d44b may be odd multiples of λ / 4, where λ is the wavelength of acoustic waves propagating laterally at the resonant frequency in the stacked structure in the thickness direction of each distance corresponding region. Specifically, the d21a interval corresponds to the top electrode raised portion (including the top electrode, raised structure layer, piezoelectric layer, and bottom electrode), the d11a interval corresponds to the top electrode cantilever portion (including the top electrode and raised structure layer), the d40a interval corresponds to the bottom electrode and piezoelectric layer portion, and the d44b interval corresponds to the first acoustic impedance layer, the bottom electrode, and the piezoelectric layer portion.

[0132] Figure 3A A bulk acoustic wave resonator according to another exemplary embodiment of the present invention is similar to Figure 2 The MOM' line in the Figure 2CAn enlarged partial cross-sectional schematic diagram of the bottom electrode 2, which shows that the electrode connection end of the bottom electrode 2 is covered by a portion of the first acoustic impedance layer, and the non-electrode connection end of the bottom electrode 2 is spaced apart from the first acoustic impedance layer 3 in the lateral direction. Figure 3A In the embodiment, the bottom electrode is provided with a cantilever 10 and a bridge structure 13 as well as a protruding structure 11 and a recessed structure 12, and the first acoustic impedance layer 3 does not cover the bridge structure. Figure 3A In the embodiment, the non-electrode connection end of the bottom electrode 2 is a cantilever structure. Figure 3A As shown, the width of the bridge structure 13 is d12b, optionally in the range of 0-50μm. The overlapping area of ​​the non-electrode connection end of the top electrode and the bridge structure of the bottom electrode in the thickness direction of the resonator (or the lateral distance between the inner edge of the bridge structure and the endpoint of the non-electrode connection end of the top electrode) is d43b, the value of which has a significant impact on the performance of the resonator. d43b is smaller than d12b, and the width of d43b is in the range of 0μm–20μm, thereby ensuring that the non-electrode connection end of the top electrode falls within the projection of the bridge structure of the bottom electrode.

[0133] exist Figure 3A In the case of the bottom electrode, the non-electrode connection end ( Figure 3A The lateral distance between the outer edge of the bottom electrode cantilever (in the middle) and the first acoustic impedance layer 3 is d40b; the lateral distance between the outer edge of the bottom electrode bridge structure and the first acoustic impedance layer 3 is d41b. Because the first acoustic impedance layer 3 reflects shear waves that leak out of the filter, and the distance between them plays a significant role in wave and energy reflection, the setting or selection of d40b and d41b has a significant impact on the performance of the resonator.

[0134] In an optional embodiment, d11b, d12b, d40b, d41b, d43b, d21b, and d22b may be odd multiples of λ / 4, where λ is the wavelength of the acoustic wave propagating laterally at the resonant frequency in the stacked structure in the thickness direction of each distance corresponding region. In a specific example, the d11b interval corresponds to the bottom electrode cantilever portion (including the bottom electrode and the raised structure layer), the d12b interval corresponds to the bottom electrode bridge portion (including the bottom electrode and the raised structure layer), the d40b and d43b intervals correspond to the top electrode and piezoelectric layer portion, the d41b interval corresponds to the bottom electrode and piezoelectric layer portion (optionally, also including the raised structure layer), and the d21b and d22b intervals correspond to the bottom electrode raised portion (including the top electrode, the piezoelectric layer, the bottom electrode, and the raised structure layer).

[0135] In addition, d41b can also be a negative value. When d41b is a negative value, that is, the first acoustic impedance layer 3 covers a portion of the bottom electrode bridge structure, it is necessary to ensure that d12b is greater than the absolute value of d41b, that is, the edge of the first acoustic impedance layer 3 falls into the bottom electrode bridge structure.

[0136] Figure 3B A bulk acoustic wave resonator according to another exemplary embodiment of the present invention is similar to Figure 2 1 is a schematic cross-sectional view taken along the NON' line in FIG, which shows the non-electrode connection ends of the bottom electrode 2 and the top electrode 6, and the non-electrode connection end of the bottom electrode 2 is spaced apart from the first acoustic impedance layer.

[0137] exist Figure 3B In the lateral direction, when there is no release hole 9 between the bottom electrode cantilever and the first acoustic impedance layer 3, the distance between the outer edge of the cantilever and the first acoustic impedance layer 3 is d40b.

[0138] exist Figure 3B in Figure 3B The left end of the top electrode is the non-electrode connection end ( Figure 3B The lateral distance between the non-electrode connection end (which has no cantilever, i.e., a non-cantilever structure) and the first acoustic impedance layer 3 is d44a.

[0139] like Figure 3B As shown, the outer edge of the bottom electrode cantilever ( Figure 3B The distance between the non-electrode connection end of the top electrode (on the left side) and the non-electrode connection end of the top electrode is d49b. Among them, d49b can be positive or negative. When d49b is a negative value, that is, the non-electrode connection end of the top electrode falls in the projection of the cantilever structure of the bottom electrode, at this time, it is necessary to set d11b to be greater than the absolute value of d49b, so that the effective area of ​​the resonator is defined by the inner edge of the cantilever structure of the bottom electrode. In addition, d49b can be further set to be greater than d40b, so that the non-electrode connection end of the top electrode partially overlaps with the first acoustic impedance layer 3.

[0140] like Figure 3B As shown, the non-electrode connection end of the top electrode 6 is a non-cantilever structure, and a release hole 9 can be provided between the outer edge of the non-electrode connection end and the first acoustic impedance layer 3 in the lateral direction of the resonator.

[0141] In alternative embodiments, d40b is within the range of 0-50 μm; and / or d44a is within the range of 0-50 μm; and / or d49b is within the range of 0-20 μm.

[0142] In an optional embodiment, d21b, d11b, d49b, and d44a may be odd multiples of λ / 4, where λ is the wavelength of acoustic waves propagating laterally at the resonant frequency of the stacked structure in the thickness direction of each distance corresponding to the region. Specifically, the d21b interval corresponds to the bottom electrode raised portion (including the top electrode, the piezoelectric layer, the bottom electrode, and the raised structure layer), the d11b interval corresponds to the bottom electrode cantilever portion (including the bottom electrode and the raised structure layer), the d49b interval corresponds to the top electrode and piezoelectric layer portion, and the d44a interval corresponds to the piezoelectric layer portion.

[0143] In the present invention, the widths of the cantilevers and bridge structures on the top electrode may be the same as or different from those of the cantilevers and bridge structures on the bottom electrode. The widths of the cantilevers or bridge structures on the top and / or bottom electrodes may be the same or different for different sides of the same resonator polygon, all within the scope of the present invention.

[0144] Figure 4A A bulk acoustic wave resonator according to another exemplary embodiment of the present invention is similar to Figure 2 The MOM' line in the Figure 2C , which shows that both the bottom electrode and the top electrode are provided with a cantilever 10 and a bridge structure 13 as well as a protruding structure 11 and a recessed structure 12.

[0145] It should be noted that, in the present invention, the same structure has the same parameter mark, and when the mark is not shown, it still has the same or similar meaning as the above description, for example, Figure 4A The width dimensions of the bottom electrode protrusion structure, recessed structure, and bridge wing structure are not shown. Figure 4B and Figure 4C The width dimensions of the top electrode protrusion structure, recessed structure, and bridge wing structure are not shown.

[0146] exist Figure 4A In the embodiment, the bridge structure of the electrode is spaced apart from the first acoustic impedance layer 3 in the lateral direction, that is, Figure 4A d41a and d41b shown in the figure are both greater than 0. In an optional embodiment, d41a and d41b may be odd multiples of λ / 4, where λ is the wavelength of the acoustic wave propagating laterally at the resonant frequency in the stacked structure in the thickness direction of each distance corresponding to the region. In the specific example, the interval d41a corresponds to the top electrode and the piezoelectric layer portion (optionally, also including the raised structure layer), and the interval d41b corresponds to the bottom electrode and the piezoelectric layer portion (optionally, also including the raised structure layer).

[0147] Figure 4B A bulk acoustic wave resonator according to another exemplary embodiment of the present invention is similar to Figure 2 The MOM' line in the Figure 2C The enlarged partial cross-sectional schematic diagram shows that both the bottom electrode and the top electrode are provided with cantilevers and bridge structures as well as convex structures and concave structures, wherein the bridge structure of the top electrode 6 partially overlaps with the first acoustic impedance layer 3 in the thickness direction. Figure 4B As shown, in the lateral direction of the resonator, the outer edge of the bridge structure of the top electrode is outside the boundary of the first acoustic impedance layer 3. The width of this overlapping portion corresponds to d41a.

[0148] exist Figure 4B In the figure, the cantilever and bridge structure as well as the first and second acoustic impedance layers are all for enhancing the reflection of shear waves. Therefore, in order to achieve a synergistic enhancement effect of the cantilever and bridge structure and the acoustic impedance layer on the reflection of shear waves, Figure 4B The boundary of the first acoustic impedance layer 3 in the top electrode partially overlaps with the bridge structure region of the top electrode. In an optional embodiment, d41a and d40b are odd multiples of λ / 4, where λ is the wavelength of acoustic waves propagating laterally in the stacked structure at the resonant frequency along the thickness direction of each distance corresponding to the region. In this specific example, the interval d41a corresponds to the piezoelectric layer and the first acoustic impedance layer, while the interval d40b corresponds to the piezoelectric layer.

[0149] Figure 4C A bulk acoustic wave resonator according to another exemplary embodiment of the present invention is similar to Figure 2 The MOM' line in the Figure 2C An enlarged partial cross-sectional schematic diagram of FIG, showing that both the bottom electrode and the top electrode are provided with cantilevers and bridge structures, wherein the bridge structure of the bottom electrode partially overlaps with the first acoustic impedance layer in the thickness direction. Figure 4C As shown, in the lateral direction of the resonator, the outer edge of the bridge structure of the bottom electrode is outside the boundary of the first acoustic impedance layer 3, that is, the first acoustic impedance layer 3 covers a portion of the bottom electrode bridge structure. The lateral distances between the cantilever of the top electrode and the cantilever of the bottom electrode and the first acoustic impedance layer 3 are d40a and d40b, respectively, and the lateral distances between the bridge structure of the top electrode and the bridge structure of the bottom electrode and the first acoustic impedance layer 3 are d41a and d41b, respectively. By adjusting the size of d41b, the actual suspended width of the bottom electrode bridge (the difference between d12b and d41b) can be changed, thereby changing the reflection characteristics of the bridge structure for shear waves, achieving a synergistic enhancement effect of the reflection of shear waves by the cantilever / bridge structure and the acoustic impedance layer. In an optional embodiment, d41b and d12b-d41b are odd multiples of λ / 4, where λ is the wavelength of the acoustic wave propagating laterally at the resonant frequency in the stacked structure in the thickness direction of the corresponding region at each distance. In a specific example, the interval d41b corresponds to the bottom electrode bridge structure portion and the first acoustic impedance layer portion, and the interval d12b-d41b corresponds to the bridge structure portion of the bottom electrode.

[0150] Figure 4B and 4C The structure shown can also be integrated into one structure, in which the edge of the first acoustic impedance layer below the electrode connection end of the top electrode falls into the projection of the bridge structure of the electrode connection end of the top electrode, and the edge of the first acoustic impedance layer below the electrode connection end of the bottom electrode falls into the projection of the bridge structure of the electrode connection end of the bottom electrode.

[0151] Figure 5A A bulk acoustic wave resonator according to another exemplary embodiment of the present invention is similar to Figure 2 The NON' line in the Figure 2C An enlarged partial cross-sectional schematic diagram of FIG, showing that both the top electrode and the bottom electrode are provided with cantilevers and convex structures and concave structures. Figure 5A As shown, the outer edges of the cantilevered fins of the top electrode and the bottom electrode are flush in the thickness direction.

[0152] Figure 5B A bulk acoustic wave resonator according to another exemplary embodiment of the present invention is similar to Figure 1 The MON line in the intercept is similar to Figure 2C An enlarged partial cross-sectional schematic diagram of FIG, wherein the non-electrode connection end of the top electrode is provided with a cantilever, and the non-electrode connection end of the bottom electrode is provided with a bridge structure. Figure 5B In the figure, it can be seen that there is an overlapping area between the bridge structure of the bottom electrode and the first acoustic impedance layer 3, and the lateral width of this area corresponds to d41b. By optimizing the widths of d41b and d12b, it is possible to achieve a synergistic enhancement effect on the reflection of transverse waves by the bridge structure and the acoustic impedance layer. In an optional embodiment, d41b and d12b-d41b are odd multiples of λ / 4, and λ is the wavelength of the sound wave propagated laterally at the resonant frequency in the stacked structure in the thickness direction of each distance corresponding to the region. In the specific example, the d41b interval corresponds to the bottom electrode bridge structure portion and the first acoustic impedance layer portion, and the d12b-d41b interval corresponds to the bottom electrode bridge structure portion. At the same time, compared to Figure 5A The structure shown, Figure 5B The illustrated structure improves the mechanical stability of the resonator and more easily conducts heat generated during operation of the resonator to the substrate through the electrodes and the first acoustic impedance layer 3, thereby increasing the power capacity of the resonator. However, the present invention is not limited to this. The first acoustic impedance layer 3 may not overlap with the bridge structure of the bottom electrode, but still cover the end of the bottom electrode. Alternatively, the first acoustic impedance layer 3 may be spaced apart from the bottom electrode.

[0153] Figure 5C A bulk acoustic wave resonator according to another exemplary embodiment of the present invention is similar to Figure 1 The NON' line in the Figure 2C An enlarged partial cross-sectional schematic diagram of the top electrode is shown, showing a bridge structure provided at the non-electrode connection end of the top electrode and a cantilever structure provided at the non-electrode connection end of the bottom electrode. As shown in FIG5C , the edge of the top electrode bridge structure is inboard of the edge of the first acoustic impedance layer 3. However, the present invention is not limited to this. The edge of the top electrode bridge structure may also cross the edge of the first acoustic impedance layer 3, thereby partially overlapping the top electrode bridge structure and the first acoustic impedance layer 3.

[0154] exist Figures 5A-5CIn the example shown, the width of the cantilever on the top electrode can be the same as or different from that of the cantilever on the bottom electrode. The widths of the cantilever and bridge structures on the top or bottom electrode can be the same or different on the corresponding polygons. The widths of the protruding and recessed structures on the top or bottom electrode can be the same or different on the corresponding polygons.

[0155] The thickness and width changes of the boundary structure of the resonator will have a significant impact on the propagation and reflection of the shear wave. Taking the relative position relationship between the cantilever and the bridge structure on the top electrode and the bottom electrode as an example, when the two overlap (for example Figure 5A As shown in the figure, the cantilever is flush in the thickness direction), there is only one thickness change caused by the cantilever and the bridge structure, so the generation or suppression of shear waves can only occur once. However, when the cantilever and the bridge structure have different positions in the relationship between the top electrode and the bottom electrode, such as the attached Figure 6A When Δd1 and Δd5 are not equal to zero, it will have a greater benefit in improving the Q value of the resonator.

[0156] Figure 6A A bulk acoustic wave resonator according to another exemplary embodiment of the present invention is similar to Figure 2 The MOM' line in the Figure 2C An enlarged partial cross-sectional schematic diagram shows that both the top electrode and the bottom electrode are provided with cantilevers and bridge structures, wherein the inner edges of the cantilevers and the bridge structure of the top electrode are respectively located outside the inner edges of the bridge structure and the cantilevers of the bottom electrode.

[0157] Figure 6B A bulk acoustic wave resonator according to another exemplary embodiment of the present invention is similar to Figure 2 The MOM' line in the Figure 2C An enlarged partial cross-sectional schematic diagram shows that both the top electrode and the bottom electrode are provided with cantilevers and bridge structures, wherein the inner edges of the cantilevers and the bridge structure of the top electrode are respectively located on the inner sides of the bridge structure and the inner edges of the cantilevers of the bottom electrode.

[0158] More specifically, Figure 6A and 6B As shown, the lateral distance or spacing between the inner edge of the cantilever of the top electrode and the inner edge of the bridge structure of the bottom electrode is Δd1, and the lateral distance or spacing between the inner edge of the cantilever of the bottom electrode and the inner edge of the bridge structure of the top electrode is Δd5.

[0159] In addition, if Figure 6A and 6BAs shown, there is a gap Δd2 in the lateral direction between the inner edge of the convex structure on the cantilever side of the top electrode 6 and the inner edge of the convex structure on the bridge structure side of the bottom electrode 2; there is a gap Δd6 in the lateral direction between the inner edge of the convex structure on the bridge structure side of the top electrode 6 and the inner edge of the convex structure on the cantilever side of the bottom electrode 2; there is a gap Δd3 in the lateral direction between the inner edge of the concave structure on the cantilever side of the top electrode 6 and the inner edge of the concave structure on the bridge structure side of the bottom electrode 2; there is a gap Δd4 in the lateral direction between the inner edge of the concave structure on the bridge structure side of the top electrode 6 and the inner edge of the concave structure on the cantilever side of the bottom electrode 2.

[0160] The value of Δd1-Δd6 has a great influence on the performance of the resonator.

[0161] In one embodiment of the present invention, Δd1 is in the range of 0–20 μm; and / or Δd5 is in the range of 0–20 μm; Δd2 is in the range of 0–20 μm; and / or Δd6 is in the range of 0–20 μm; and / or Δd3 is in the range of 0–20 μm; and / or Δd4 is in the range of 0–20 μm.

[0162] Figure 7 FIG. 4 is a schematic cross-sectional view of a bulk acoustic wave resonator assembly according to an exemplary embodiment of the present invention. Figure 7 Two BAW resonators are shown in FIG, which share the same substrate 5. Figure 7 In the example, the number of resonators can be more. In addition, Figure 7 In the embodiment shown, the top and bottom electrodes of the two resonators are both provided with cantilever and bridge structures, but the present invention is not limited thereto. The resonators in the assembly may be Figure 1A - Figure 6B The resonator corresponding to any of the structures shown in .

[0163] In the present invention, the first acoustic impedance layer 3 and the second acoustic impedance layer 4 may together form an acoustic impedance structure. However, the present invention is not limited thereto. In other words, the arrangement of the acoustic impedance layers is not limited thereto. Alternatively, the acoustic impedance structure may include a first acoustic impedance layer and a second acoustic impedance layer arranged adjacent to each other in a transverse direction, or a first acoustic impedance layer, a second acoustic impedance layer, and a first acoustic impedance layer, or a combination thereof.

[0164] In a further embodiment, the two resonators are adjacent in the lateral direction and respectively have a first acoustic impedance structure and a second acoustic impedance structure, and the two acoustic impedance structures share at least one first acoustic impedance layer 3 or at least one second acoustic impedance layer 4 .

[0165] In one embodiment, three acoustic impedance layers are included between the acoustic mirrors of the two resonators, namely, a first acoustic impedance layer, a second acoustic impedance layer, and a first acoustic impedance layer. The two resonators at least share the second acoustic impedance layer 4 located in the middle.

[0166] In one embodiment, five acoustic impedance layers are located between the acoustic mirrors of the two resonators: a first acoustic impedance layer, a second acoustic impedance layer, a first acoustic impedance layer, a second acoustic impedance layer, and a first acoustic impedance layer. The two resonators share at least the first acoustic impedance layer 3 located in the middle. For a single resonator, the acoustic impedance structure surrounding the acoustic mirror 8 includes, arranged from the inside to the outside, the first acoustic impedance layer 3, the second acoustic impedance layer 4, and the first acoustic impedance layer 3.

[0167] The connection method between adjacent resonators is not limited to the above. Adjacent resonators may not be electrically connected, but multiple acoustic impedance layers may be present between them. Furthermore, only one acoustic impedance layer (the first acoustic impedance layer) may be present between adjacent resonators. Adding more first acoustic impedance layers 3 and second acoustic impedance layers 4 can create more reflective interfaces, further reducing acoustic wave leakage and increasing the Q value of the resonator. Furthermore, by selecting the number and / or width of the first and second acoustic impedance layers, the pattern density of the first and second acoustic impedance layers 3 and 4 can be made more uniform, making it easier to form a flat film using a CMP (chemical mechanical polishing) process.

[0168] In one embodiment of the present invention, Figure 2A and 2B As shown, the angle β formed between the outer surface of the first acoustic impedance layer 3 and the bottom surface of the piezoelectric layer can be selected to be in the range of 100°-160°, specifically, 100°, 120°, 160°, etc. Selecting this angle facilitates filling the second acoustic impedance layer 4 after patterning the first acoustic impedance layer 3.

[0169] In one embodiment of the present invention, Figure 2B As shown, the angle α formed between the outer side of the end surface of the bottom electrode 2 and the bottom surface of the piezoelectric layer 1 can be selected to be in the range of 90°-160°, specifically, 90°, 100°, 120°, 160°, etc. Selecting this angle facilitates filling the first acoustic impedance layer 3 and the second acoustic impedance layer 4.

[0170] Figure 9 A bulk acoustic wave resonator according to an exemplary embodiment of the present invention is similar to Figure 2A schematic cross-sectional view taken along the MOM' line in FIG, showing the electrode lead-out region of the bottom electrode and the electrode lead-out region of the top electrode, wherein the electrode connection end of the bottom electrode is covered by a portion of the first acoustic impedance layer, and the non-electrode connection end of the bottom electrode is spaced apart from the first acoustic impedance layer in the lateral direction. Figure 9 In the embodiment, both the top electrode and the bottom electrode are provided with cantilever and bridge structures. Figure 2A In the case of Figure 9 In the embodiment of the present invention, the angle β is an acute angle. Figure 9 As shown, the angle β formed between the outer side surface of the first acoustic impedance layer 3 and the bottom surface of the piezoelectric layer can be selected to be in the range of 20°-80°, specifically, 20°, 60°, 80°, etc.

[0171] For example, Figure 2A and 2B As shown, the piezoelectric layer 1 is provided with a bottom electrode via 9a (see the following description) Figure 8K ), the electrode lead portion 6a is electrically connected to the electrode connection end of the bottom electrode 2 through the via 9a. As described later Figure 8N and 8O As shown, the electrode lead portion 6a is formed of the same material as the top electrode 6 and has a lead portion arranged in the same layer as the top electrode 6. However, it is not excluded that the electrode lead portion 6a can also be formed separately from other materials different from the top electrode 6.

[0172] Refer to the following Figures 8A-8O Example Figure 2A The fabrication process of a single crystal piezoelectric thin film bulk acoustic resonator is shown.

[0173] like Figure 8A As shown, a single crystal piezoelectric thin film layer (i.e., a single crystal piezoelectric layer) 1, such as single crystal aluminum nitride (AlN) or gallium nitride (GaN), is deposited on the surface of a substrate 5a (e.g., silicon or silicon carbide). The deposition process used includes, but is not limited to, MOCVD (metal organic chemical vapor deposition), MBE (molecular beam epitaxy), CBE (chemical molecular beam epitaxy), and LPE (liquid phase epitaxy). Alternatively, an interface layer is formed on the surface of an auxiliary substrate Aux1 (e.g., lithium niobate or lithium tantalate substrate) through ion implantation, and the piezoelectric thin film layer 1 is formed above the interface layer. In this case, the material of the piezoelectric thin film layer 1 is the same as that of the substrate 5a. The upper surface of the piezoelectric layer 1 is bonded to the substrate 5a.

[0174] like Figure 8B As shown, a sacrificial layer of bottom electrode cantilever and bridge structure is prepared on the piezoelectric layer. The material of the sacrificial layer can be dielectric materials such as silicon nitride, silicon oxide, polysilicon, amorphous silicon, etc., and the sacrificial layer structure 14 is obtained by patterning through an etching process.

[0175] like Figure 8CAs shown, a bottom electrode protrusion structure 11 is prepared, and a metal layer is deposited on the single crystal piezoelectric layer by CVD (chemical vapor deposition), PVD (physical vapor deposition), PECVD (plasma enhanced chemical vapor deposition), evaporation, sputtering and other similar thin film deposition processes. The material of the metal layer can be the same as or different from the metal material of the bottom electrode, and is patterned by an etching process.

[0176] like Figure 8D As shown, a bottom electrode layer is deposited on the single crystal piezoelectric layer by a thin film deposition process similar to CVD (chemical vapor deposition), PVD (physical vapor deposition), PECVD (plasma enhanced chemical vapor deposition), evaporation, sputtering, etc., and then the bottom electrode 2 is obtained by an etching process.

[0177] like Figure 8E As shown, a recess forming structure 12A for forming the recess structure 12 is prepared on the bottom electrode 2. The material of the recess forming structure 12A can be the same as or different from the metal material of the bottom electrode, and is patterned by an etching process.

[0178] like Figure 8F As shown, in Figure 8E A layer of first acoustic impedance material is deposited on the surface of the piezoelectric layer 1 and the bottom electrode 2 of the structure shown, and patterned to form a first acoustic impedance layer 3. The first acoustic impedance material can be aluminum nitride, silicon dioxide, silicon nitride, polysilicon, amorphous silicon, etc.

[0179] like Figure 8G As shown, in Figure 8F The second acoustic impedance material is deposited on the surface of the piezoelectric layer 1, the first acoustic impedance layer 3 and the bottom electrode 2 of the obtained structure, so that the second acoustic impedance material fills the gap between the first acoustic impedance layer 3 (the gap corresponds to the acoustic mirror cavity). The material of the second acoustic impedance layer can be silicon dioxide, doped silicon dioxide, polycrystalline silicon, amorphous silicon, etc., but is different from the material of the first acoustic impedance layer.

[0180] like Figure 8H As shown, the second acoustic impedance material is polished flat by CMP (chemical mechanical polishing) until the first acoustic impedance layer 3 is exposed. The second acoustic impedance material located outside the first acoustic impedance layer 3 constitutes the second acoustic impedance layer 4, while the second acoustic impedance material located between the first acoustic impedance layers 3 constitutes a sacrificial layer. In other words, in this embodiment, the second acoustic impedance material is also a sacrificial material.

[0181] like Figure 8I As shown, the substrate 5 is bonded to the lower side of the first acoustic impedance layer 3 and the second acoustic impedance layer 4. Optionally, the surface of the substrate 5 may also have an auxiliary bonding layer (not shown in the figure), such as silicon dioxide, silicon nitride, etc.

[0182] like Figure 8J As shown, the substrate 5a is removed by grinding, etching or ion implantation layer separation to expose the upper surface of the piezoelectric layer 1. Optionally, the separation interface is subjected to CMP treatment to make the surface smooth and have low roughness.

[0183] like Figure 8K As shown, a through hole 9a is etched in the piezoelectric layer 1 by photolithography and etching processes. At the same time, a sacrificial layer release hole (not shown in the figure) is etched on the piezoelectric layer 1. The through hole is directly connected to the electrode connection end of the bottom electrode, or the through hole is directly connected to the acoustic mirror cavity or directly connected to the second acoustic impedance material located in the acoustic mirror cavity, namely the sacrificial layer.

[0184] like Figure 8L As shown, a sacrificial layer of a top electrode cantilever and a bridge structure is prepared on the piezoelectric layer. The material of the sacrificial layer can be a dielectric material such as silicon nitride, silicon oxide, polysilicon, amorphous silicon, etc., and is patterned by an etching process.

[0185] like Figure 8M As shown, a recessed forming structure for forming a recessed structure of a top electrode and a protruding structure 11 are prepared, which can be achieved as follows: a metal layer is deposited on the single crystal piezoelectric layer by CVD (chemical vapor deposition), PVD (physical vapor deposition), PECVD (plasma enhanced chemical vapor deposition), evaporation, sputtering and other similar thin film deposition processes, the material of which can be the same or different metal material as the bottom electrode, and is patterned by an etching process.

[0186] like Figure 8N As shown, an electrode material layer for the top electrode 6 is deposited, which covers the top surface of the piezoelectric layer and enters the via 9a and the release hole. The electrode material layer is then etched to remove the electrode material in the release hole and patterned to form the top electrode 6.

[0187] like Figure 8O As shown, a conductive material is deposited by a thin film deposition process and then patterned to form an electrode connection portion (bonding pad) or an electrode electrical connection layer 7, including a top electrode connection layer and a bottom electrode connection layer.

[0188] Afterwards, an etchant is introduced through the release hole to release the second acoustic impedance layer material or the sacrificial layer in the acoustic mirror cavity 8, and the corresponding Figure 2A structure.

[0189] In the above manufacturing process, the first acoustic impedance layer 3 is manufactured first, and then the second acoustic impedance layer 4 is manufactured. Therefore, the angle α formed between the outer side surface of the first acoustic impedance layer 3 and the bottom surface of the piezoelectric layer is within the range of 100°-160°. However, the second acoustic impedance layer 4 can also be manufactured first, and then the first acoustic impedance layer 3. Based on different manufacturing processes, the angle between the outer side surface of the first acoustic impedance layer 3 and the bottom surface of the piezoelectric layer can be Figure 2A Different than shown in .

[0190] For manufacturing e.g. Figure 1I The structure shown in the figure can be omitted. Figure 8B and 8L The corresponding steps and the release of the sacrificial layer structure 14 in the subsequent release step are omitted.

[0191] For manufacturing e.g. Figure 1A The structure shown in the figure can be omitted. Figures 8B-8C , 8E steps.

[0192] For manufacturing e.g. Figure 1D The structure shown can then be performed, for example, through steps 8B, 8C, and 8L.

[0193] In the present invention, the numerical range mentioned may be not only the endpoint values, but also the median value or other values ​​between the endpoint values, all of which are within the protection scope of the present invention.

[0194] In the present invention, the terms "up" and "down" are relative to the bottom surface of the base of the resonator. For a component, the side close to the bottom surface is the lower side, and the side away from the bottom surface is the upper side.

[0195] In the present invention, "inside" and "outside" refer to the center of the effective area of ​​the resonator (the overlapping area of ​​the piezoelectric layer, top electrode, bottom electrode, and acoustic mirror in the thickness direction of the resonator constitutes the effective area) in the lateral direction or radial direction. The side or end of a component close to the center is the inner side or inner end, while the side or end of the component away from the center is the outer side or outer end. For a reference position, being located inside the position means being between the position and the center (the center of the resonator effective area) in the lateral direction or radial direction, and being located outside the position means being further away from the center (the center of the resonator effective area) than the position in the lateral direction or radial direction.

[0196] It should be pointed out that in Figure 1 and Figure 2 In the embodiment, the first acoustic impedance layer and the second acoustic impedance layer both form a ring around the acoustic mirror of the resonator. However, the second acoustic impedance layer may be embedded in a local position of the first acoustic impedance layer, which is within the scope of protection of the present invention.

[0197] In the present invention, the material of the piezoelectric layer may also be a non-single crystal material.

[0198] In the present invention, in addition to the above-mentioned embodiments, the non-electrode connection end of the top electrode may be provided with a cantilever, and the non-electrode connection end of the bottom electrode may also be provided with a cantilever; or, the non-electrode connection end of the top electrode may be provided with a recessed structure, and the non-electrode connection end of the bottom electrode may also be provided with a recessed structure; or, the non-electrode connection end of the top electrode may be provided with a protruding structure, and the non-electrode connection end of the bottom electrode may also be provided with a protruding structure. The inner edges of the cantilever at the non-electrode connection end may be aligned or staggered with each other, the inner edges of the protruding structure at the non-electrode connection end may be aligned or staggered with each other, and the inner edges of the recessed structure at the non-electrode connection end may be aligned or staggered with each other.

[0199] As those skilled in the art will appreciate, the BAW resonator according to the present invention can be used to form filters or other semiconductor devices.

[0200] Based on the above, the present invention proposes the following technical solutions:

[0201] 1. A bulk acoustic wave resonator, comprising:

[0202] substrate;

[0203] Acoustic mirror;

[0204] bottom electrode;

[0205] a top electrode; and

[0206] A piezoelectric layer is provided between the bottom electrode and the top electrode,

[0207] in:

[0208] An acoustic impedance structure is provided between the piezoelectric layer and the substrate;

[0209] The acoustic impedance structure includes a first acoustic impedance layer and a second acoustic impedance layer arranged adjacent to each other in a lateral direction, the first acoustic impedance layer and the second acoustic impedance layer have different acoustic impedances, and the acoustic mirror is located between the first acoustic impedance layers in the lateral direction of the resonator; and

[0210] The edge portion of the bottom electrode and / or the top electrode is provided with a protruding structure and / or a concave structure.

[0211] 2. The resonator according to item 1, wherein:

[0212] The bottom electrode and / or the top electrode are also provided with cantilevers and / or bridge structures, and the same electrode is provided with the convex structure and / or concave structure, cantilevers and / or bridge structures at the same time, and the cantilevers and / or bridge structures are provided on the outside of the convex structure and the concave structure.

[0213] 3. The resonator according to 2, wherein:

[0214] The non-electrode connection end of the same electrode is provided with a cantilever, and in the lateral direction of the resonator, there is a first distance (d40) between the outer edge of the cantilever and the corresponding first acoustic impedance layer in the lateral direction; or

[0215] The non-electrode connection end of the same electrode is a non-cantilever structure, and in the lateral direction of the resonator, there is a third distance (d44) between the outer edge of the non-electrode connection end and the corresponding first acoustic impedance layer in the lateral direction.

[0216] 4. The resonator according to 3, wherein:

[0217] The first distance (d40) is in the range of 0-50 μm; and / or

[0218] The third distance (d44) is in the range of 0-50 μm.

[0219] 5. The resonator according to claim 3, wherein:

[0220] In the lateral direction of the resonator, on the side of the electrode connection terminal of the bottom electrode, the outer edge of the cantilever of the top electrode is inside the boundary of the first acoustic impedance layer; or

[0221] In the lateral direction of the resonator, on the side of the electrode connection terminal of the bottom electrode, the outer edge of the cantilever of the top electrode is outside the boundary of the first acoustic impedance layer.

[0222] 6. The resonator according to 5, wherein:

[0223] The first distance (d40) is an odd multiple of λ1 / 4, and λ1 is the wavelength of the sound wave propagating laterally at the resonance frequency of the stacked structure in the thickness direction of the region corresponding to the first distance.

[0224] 7. The resonator according to 2, wherein:

[0225] The width of the raised structure in the lateral direction of the resonator is in the range of 0–50 μm; and / or

[0226] The width of the recessed structures is in the range of 0–50 μm; and / or

[0227] The overhang width (d11) is in the range of 0–50 μm; and / or

[0228] The width of the bridge structure is in the range of 0–50 μm.

[0229] 8. The resonator according to claim 3, wherein:

[0230] The non-electrode connection end of the bottom electrode and / or the top electrode is provided with a cantilever.

[0231] 9. The resonator according to any one of 2 to 8, wherein:

[0232] The electrode connection end and / or the non-electrode connection end of the bottom electrode and / or the top electrode are provided with a bridge structure; and

[0233] In the lateral direction of the resonator, there is a fifth distance (d41) between the outer edge of the bridge structure and the corresponding first acoustic impedance layer.

[0234] 10. The resonator according to claim 9, wherein:

[0235] The fifth distance (d41) is in the range of 0-50 μm.

[0236] 11. The resonator according to 9, wherein:

[0237] In a lateral direction of the resonator, an outer edge of the bridge structure is outside a boundary of the first acoustic impedance layer.

[0238] 12. The resonator according to claim 9, wherein:

[0239] The fifth distance (d41) is an odd multiple of λ2 / 4, where λ2 is the wavelength of the acoustic wave propagating laterally at the resonance frequency in the stacked structure in the thickness direction of the region corresponding to the fifth distance.

[0240] 13. The resonator according to any one of 8 to 12, wherein:

[0241] The electrode connection end and / or the non-electrode connection end of one of the top electrode and the bottom electrode is provided with a bridge structure, and the non-electrode connection end of the other of the top electrode and the bottom electrode is provided with a cantilever; or

[0242] The non-electrode connection ends of the top electrode and the bottom electrode are both provided with cantilevers.

[0243] 14. The resonator according to 13, wherein:

[0244] Each of the top electrode and the bottom electrode is provided with a protrusion structure and a recess structure, a cantilever and a bridge structure.

[0245] 15. The resonator according to 14, wherein:

[0246] In the thickness direction of the resonator, the inner edge of the cantilever of one of the top electrode and the bottom electrode is aligned with the inner edge of the bridge structure of the other of the top electrode and the bottom electrode; and / or

[0247] An inner edge of the cantilever of one of the top electrode and the bottom electrode is aligned with an inner edge of the cantilever of the other of the top electrode and the bottom electrode.

[0248] 16. The resonator according to 14, wherein:

[0249] An inner edge of the cantilever of one of the top electrode and the bottom electrode is offset from an inner edge of the bridge structure of the other of the top electrode and the bottom electrode in the lateral direction; and / or

[0250] An inner edge of the cantilever of one of the top electrode and the bottom electrode is offset from an inner edge of the cantilever of the other of the top electrode and the bottom electrode in the lateral direction.

[0251] 17. The resonator according to 16, wherein:

[0252] At the non-electrode connection end of one of the top electrode and the bottom electrode, a first gap (Δd1) exists in the lateral direction between the inner edge of the cantilever of one of the top electrode and the bottom electrode and the inner edge of the bridge structure of the other of the top electrode and the bottom electrode; and / or

[0253] At the electrode connection end of said one of the top electrode and the bottom electrode, there is a second gap (Δd5) in the lateral direction between the inner edge of the cantilever of one of the top electrode and the bottom electrode and the inner edge of the bridge structure of the other of the top electrode and the bottom electrode; and / or

[0254] There is a third interval (Δd2) in the lateral direction between the inner edge of the raised structure on the cantilever side of the top electrode and the inner edge of the raised structure on the bridge structure side of the bottom electrode, or there is a third interval (Δd2) in the lateral direction between the inner edge of the raised structure on the non-electrode connection end of the top electrode and the inner edge of the raised structure on the electrode connection end of the bottom electrode; and / or

[0255] There is a fourth interval (Δd6) in the lateral direction between the inner edge of the protruding structure on the bridge structure side of the top electrode and the inner edge of the protruding structure on the cantilever side of the bottom electrode, or there is a fourth interval (Δd6) in the lateral direction between the inner edge of the protruding structure at the electrode connection end of the top electrode and the inner edge of the protruding structure at the non-electrode connection end of the bottom electrode; and / or

[0256] There is a fifth interval (Δd3) in the lateral direction between the inner edge of the recessed structure on the cantilever side of the top electrode and the inner edge of the recessed structure on the bridge structure side of the bottom electrode, or there is a fifth interval (Δd3) in the lateral direction between the inner edge of the recessed structure at the non-electrode connection end of the top electrode and the inner edge of the recessed structure at the electrode connection end of the bottom electrode; and / or

[0257] There is a sixth gap (Δd4) in the lateral direction between the inner edge of the recessed structure on the bridge structure side of the top electrode and the inner edge of the recessed structure on the cantilever side of the bottom electrode, or there is a sixth gap (Δd4) in the lateral direction between the inner edge of the recessed structure at the electrode connection end of the top electrode and the inner edge of the recessed structure at the non-electrode connection end of the bottom electrode; and / or

[0258] There is a seventh gap in the lateral direction between the inner edge of the cantilever of the non-electrode connecting end of the top electrode and the inner edge of the cantilever of the non-electrode connecting end of the bottom electrode.

[0259] 18. The resonator according to 17, wherein:

[0260] The first spacing (Δd1) is in the range of 0–20 μm; and / or

[0261] The second spacing (Δd5) is in the range of 0–20 μm; and / or

[0262] The third spacing (Δd2) is in the range of 0–20 μm; and / or

[0263] The fourth spacing (Δd6) is in the range of 0–20 μm; and / or

[0264] The fifth interval (Δd3) is in the range of 0–20 μm; and / or

[0265] The sixth spacing (Δd4) is in the range of 0–20 μm; and / or

[0266] The seventh interval is in the range of 0–20 μm.

[0267] 19. The resonator according to 2, wherein:

[0268] The electrode connection end of one of the top electrode and the bottom electrode is provided with a bridge structure, and the non-electrode connection end of the other of the top electrode and the bottom electrode has an overlapping area (d43) with the bridge structure in the thickness direction of the resonator.

[0269] 20. The resonator according to item 1, wherein:

[0270] The edges of the bottom electrode and the top electrode are both provided with convex structures and concave structures; and

[0271] in:

[0272] There is a third gap (Δd2) between the inner edge of the protruding structure of the non-electrode connection end of the top electrode and the inner edge of the protruding structure of the electrode connection end of the bottom electrode in the lateral direction; and / or

[0273] There is a fourth gap (Δd6) between the inner edge of the raised structure of the electrode connection end of the top electrode and the inner edge of the raised structure of the non-electrode connection end of the bottom electrode in the lateral direction; and / or

[0274] There is a fifth gap (Δd3) between the inner edge of the recessed structure of the non-electrode connection end of the top electrode and the inner edge of the recessed structure of the electrode connection end of the bottom electrode in the lateral direction; and / or

[0275] There is a sixth gap (Δd4) in the lateral direction between the inner edge of the recessed structure of the electrode connection end of the top electrode and the inner edge of the recessed structure of the non-electrode connection end of the bottom electrode; and / or

[0276] An eighth interval exists between an inner edge of the protruding structure of the non-electrode connection end of the top electrode and an inner edge of the protruding structure of the non-electrode connection end of the bottom electrode in the lateral direction; and / or

[0277] There is a ninth interval in the lateral direction between an inner edge of the recessed structure of the non-electrode connection end of the top electrode and an inner edge of the recessed structure of the non-electrode connection end of the bottom electrode.

[0278] 21. The resonator according to 20, wherein:

[0279] The third spacing (Δd2) is in the range of 0–20 μm; and / or

[0280] The fourth spacing (Δd6) is in the range of 0–20 μm; and / or

[0281] The fifth interval (Δd3) is in the range of 0–20 μm; and / or

[0282] The sixth spacing (Δd4) is in the range of 0–20 μm; and / or

[0283] The eighth interval is in the range of 0–20 μm; and / or

[0284] The ninth interval is in the range of 0–20 μm.

[0285] 22. The resonator according to item 1, wherein:

[0286] The acoustic mirror is an acoustic mirror cavity;

[0287] The boundary of the acoustic mirror cavity in the lateral direction of the resonator is defined by the first acoustic impedance layer.

[0288] 23. The resonator according to item 1, wherein:

[0289] A convex structure and a concave structure are provided at the edge of the top electrode and / or the bottom electrode, and the convex structure is provided at the outside of the concave structure.

[0290] 24. The resonator according to any one of 1 to 23, wherein:

[0291] The piezoelectric layer is a single crystal piezoelectric layer.

[0292] 25. The resonator according to any one of 1 to 24, wherein:

[0293] The widths of the portions of the first acoustic impedance layer and the second acoustic impedance layer in contact with the piezoelectric layer are mλ3 / 4 and nλ4 / 4, respectively, where m and n are both odd numbers, and λ3 and λ4 are the wavelengths of acoustic waves propagating laterally at the resonant frequency at the corresponding portions of the first acoustic impedance layer and the second acoustic impedance layer in contact with the piezoelectric layer.

[0294] 26. The resonator according to any one of 1 to 24, wherein:

[0295] The material forming one of the first acoustic impedance layer and the second acoustic impedance layer is selected from aluminum nitride, silicon dioxide, silicon nitride, polycrystalline silicon, and amorphous silicon, and the material forming the other of the first acoustic impedance layer and the second acoustic impedance layer is selected from silicon dioxide, doped silicon dioxide, polycrystalline silicon, and amorphous silicon. The material forming the first acoustic impedance layer is different from the material forming the second acoustic impedance layer.

[0296] 27. The resonator according to any one of 1 to 24, wherein:

[0297] The electrode connection end of the bottom electrode is covered by a portion of the first acoustic impedance layer.

[0298] 28. A bulk acoustic wave resonator assembly comprising:

[0299] At least two resonators according to any one of 1-27, the at least two resonators sharing a same substrate.

[0300] 29. A filter comprising the BAW resonator according to any one of 1 to 27, or the BAW resonator assembly according to 28.

[0301] 30. An electronic device comprising the filter according to 29, or the BAW resonator according to any one of 1 to 27, or the BAW resonator assembly according to 28.

[0302] The electronic equipment here includes but is not limited to intermediate products such as RF front-ends, filter amplification modules, as well as terminal products such as mobile phones, WIFI, and drones.

[0303] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes may be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. A bulk acoustic wave resonator, comprising: substrate; Acoustic mirror; bottom electrode; Top electrode; and A piezoelectric layer is provided between the bottom electrode and the top electrode, in: An acoustic impedance structure is provided between the piezoelectric layer and the substrate; The acoustic impedance structure includes a first acoustic impedance layer and a second acoustic impedance layer arranged adjacent to each other in a lateral direction, the first acoustic impedance layer and the second acoustic impedance layer have different acoustic impedances, and the acoustic mirror is located between the first acoustic impedance layers in the lateral direction of the resonator; and The edge portion of the bottom electrode and / or the top electrode is provided with a protruding structure and / or a concave structure.

2. The resonator according to claim 1, wherein: The bottom electrode and / or the top electrode are also provided with cantilevers and / or bridge structures, and the same electrode is provided with the convex structure and / or concave structure, cantilevers and / or bridge structures at the same time, and the cantilevers and / or bridge structures are provided on the outside of the convex structure and the concave structure.

3. The resonator according to claim 2, wherein: The non-electrode connection end of the same electrode is provided with a cantilever, and in the lateral direction of the resonator, there is a first distance in the lateral direction between the outer edge of the cantilever and the corresponding first acoustic impedance layer; or The non-electrode connection end of the same electrode is a non-cantilever structure, and in the lateral direction of the resonator, there is a third distance in the lateral direction from the outer edge of the non-electrode connection end to the corresponding first acoustic impedance layer.

4. The resonator according to claim 3, wherein: The first distance is in the range of 0-50 μm; and / or The third distance is in the range of 0-50 μm.

5. The resonator according to claim 3, wherein: In the lateral direction of the resonator, on the side of the electrode connection terminal of the bottom electrode, the outer edge of the cantilever of the top electrode is inside the boundary of the first acoustic impedance layer; or In the lateral direction of the resonator, on the side of the electrode connection terminal of the bottom electrode, the outer edge of the cantilever of the top electrode is outside the boundary of the first acoustic impedance layer.

6. The resonator according to claim 5, wherein: The first distance is an odd multiple of λ1 / 4, and λ1 is the wavelength of the sound wave propagating laterally at the resonance frequency of the stacked structure in the thickness direction of the region corresponding to the first distance.

7. The resonator according to claim 2, wherein: The width of the raised structure in the lateral direction of the resonator is in the range of 0–50 μm; and / or The width of the recessed structures is in the range of 0–50 μm; and / or Overhang width in the range of 0–50 μm; and / or The width of the bridge structure is in the range of 0–50 μm.

8. The resonator of claim 3, wherein: The non-electrode connection end of the bottom electrode and / or the top electrode is provided with a cantilever.

9. The resonator according to any one of claims 2 to 8, wherein: The electrode connection end and / or the non-electrode connection end of the bottom electrode and / or the top electrode are provided with a bridge structure; and In the lateral direction of the resonator, there is a fifth distance between the outer edge of the bridge structure and the corresponding first acoustic impedance layer.

10. The resonator of claim 9, wherein: The fifth distance is in the range of 0-50 μm.

11. The resonator of claim 9, wherein: In a lateral direction of the resonator, an outer edge of the bridge structure is outside a boundary of the first acoustic impedance layer.

12. The resonator of claim 9, wherein: The fifth distance is an odd multiple of λ2 / 4, and λ2 is the wavelength of the sound wave propagating laterally at the resonance frequency of the stacked structure in the thickness direction of the region corresponding to the fifth distance.

13. The resonator of claim 9, wherein: The electrode connection end and / or the non-electrode connection end of one of the top electrode and the bottom electrode is provided with a bridge structure, and the non-electrode connection end of the other of the top electrode and the bottom electrode is provided with a cantilever; or The non-electrode connection ends of the top electrode and the bottom electrode are both provided with cantilevers.

14. The resonator of claim 13, wherein: Each of the top electrode and the bottom electrode is provided with a protrusion structure and a recess structure, a cantilever and a bridge structure.

15. The resonator of claim 14, wherein: In the thickness direction of the resonator, the inner edge of the cantilever of one of the top electrode and the bottom electrode is aligned with the inner edge of the bridge structure of the other of the top electrode and the bottom electrode; and / or An inner edge of the cantilever of one of the top electrode and the bottom electrode is aligned with an inner edge of the cantilever of the other of the top electrode and the bottom electrode.

16. The resonator of claim 14, wherein: An inner edge of the cantilever of one of the top electrode and the bottom electrode is offset from an inner edge of the bridge structure of the other of the top electrode and the bottom electrode in the lateral direction; and / or An inner edge of the cantilever of one of the top electrode and the bottom electrode is offset from an inner edge of the cantilever of the other of the top electrode and the bottom electrode in the lateral direction.

17. The resonator of claim 16, wherein: At the non-electrode connection end of one of the top electrode and the bottom electrode, a first gap exists in the lateral direction between an inner edge of the cantilever of one of the top electrode and the bottom electrode and an inner edge of the bridge structure of the other of the top electrode and the bottom electrode; and / or At the electrode connection end of said one of the top electrode and the bottom electrode, there is a second gap in the lateral direction between the inner edge of the cantilever of one of the top electrode and the bottom electrode and the inner edge of the bridge structure of the other of the top electrode and the bottom electrode; and / or There is a third interval in the lateral direction between the inner edge of the raised structure on the cantilever side of the top electrode and the inner edge of the raised structure on the bridge structure side of the bottom electrode, or there is a third interval in the lateral direction between the inner edge of the raised structure on the non-electrode connection end of the top electrode and the inner edge of the raised structure on the electrode connection end of the bottom electrode; and / or There is a fourth interval (Δd6) in the lateral direction between the inner edge of the protruding structure on the bridge structure side of the top electrode and the inner edge of the protruding structure on the cantilever side of the bottom electrode, or there is a fourth interval in the lateral direction between the inner edge of the protruding structure at the electrode connection end of the top electrode and the inner edge of the protruding structure at the non-electrode connection end of the bottom electrode; and / or There is a fifth interval in the lateral direction between the inner edge of the recessed structure on the cantilever side of the top electrode and the inner edge of the recessed structure on the bridge structure side of the bottom electrode, or there is a fifth interval in the lateral direction between the inner edge of the recessed structure at the non-electrode connection end of the top electrode and the inner edge of the recessed structure at the electrode connection end of the bottom electrode; and / or There is a sixth interval in the lateral direction between the inner edge of the recessed structure on the bridge structure side of the top electrode and the inner edge of the recessed structure on the cantilever side of the bottom electrode, or there is a sixth interval in the lateral direction between the inner edge of the recessed structure at the electrode connection end of the top electrode and the inner edge of the recessed structure at the non-electrode connection end of the bottom electrode; and / or There is a seventh gap in the lateral direction between the inner edge of the cantilever of the non-electrode connecting end of the top electrode and the inner edge of the cantilever of the non-electrode connecting end of the bottom electrode.

18. The resonator of claim 17, wherein: The first spacing is in the range of 0–20 μm; and / or The second spacing is in the range of 0–20 μm; and / or The third interval is in the range of 0–20 μm; and / or The fourth interval is in the range of 0–20 μm; and / or The fifth interval is in the range of 0–20 μm; and / or The sixth interval is in the range of 0–20 μm; and / or The seventh interval is in the range of 0–20 μm.

19. The resonator of claim 2, wherein: The electrode connection end of one of the top electrode and the bottom electrode is provided with a bridge structure, and the non-electrode connection end of the other of the top electrode and the bottom electrode has an overlapping area (d43) with the bridge structure in the thickness direction of the resonator.

20. The resonator of claim 1, wherein: The edges of the bottom electrode and the top electrode are both provided with convex structures and concave structures; and in: There is a third gap in the lateral direction between the inner edge of the raised structure of the non-electrode connection end of the top electrode and the inner edge of the raised structure of the electrode connection end of the bottom electrode; and / or There is a fourth gap in the lateral direction between the inner edge of the raised structure of the electrode connection end of the top electrode and the inner edge of the raised structure of the non-electrode connection end of the bottom electrode; and / or There is a fifth gap between the inner edge of the recessed structure of the non-electrode connection end of the top electrode and the inner edge of the recessed structure of the electrode connection end of the bottom electrode in the lateral direction; and / or There is a sixth gap in the lateral direction between an inner edge of the recessed structure of the electrode connection end of the top electrode and an inner edge of the recessed structure of the non-electrode connection end of the bottom electrode; and / or An eighth interval exists between an inner edge of the protruding structure of the non-electrode connection end of the top electrode and an inner edge of the protruding structure of the non-electrode connection end of the bottom electrode in the lateral direction; and / or There is a ninth interval in the lateral direction between an inner edge of the recessed structure of the non-electrode connection end of the top electrode and an inner edge of the recessed structure of the non-electrode connection end of the bottom electrode.

21. The resonator of claim 20, wherein: The third interval is in the range of 0–20 μm; and / or The fourth interval is in the range of 0–20 μm; and / or The fifth interval is in the range of 0–20 μm; and / or The sixth interval is in the range of 0–20 μm; and / or The eighth interval is in the range of 0–20 μm; and / or The ninth interval is in the range of 0–20 μm.

22. The resonator of claim 1 , wherein: The acoustic mirror is an acoustic mirror cavity; The boundary of the acoustic mirror cavity in the lateral direction of the resonator is defined by the first acoustic impedance layer.

23. The resonator of claim 1 , wherein: A convex structure and a concave structure are provided at the edge of the top electrode and / or the bottom electrode, and the convex structure is provided at the outside of the concave structure.

24. The resonator according to any one of claims 1 to 8, 10 to 12, or 14 to 23, wherein: The piezoelectric layer is a single crystal piezoelectric layer.

25. The resonator according to any one of claims 1 to 8, 10 to 12, or 14 to 23, wherein: The widths of the portions of the first acoustic impedance layer and the second acoustic impedance layer in contact with the piezoelectric layer are mλ3 / 4 and nλ4 / 4, respectively, where m and n are both odd numbers, and λ3 and λ4 are the wavelengths of acoustic waves propagating laterally at the resonant frequency at the corresponding portions of the first acoustic impedance layer and the second acoustic impedance layer in contact with the piezoelectric layer.

26. The resonator according to any one of claims 1 to 8, 10 to 12, or 14 to 23, wherein: The material forming one of the first acoustic impedance layer and the second acoustic impedance layer is selected from aluminum nitride, silicon dioxide, silicon nitride, polycrystalline silicon, and amorphous silicon, and the material forming the other of the first acoustic impedance layer and the second acoustic impedance layer is selected from silicon dioxide, doped silicon dioxide, polycrystalline silicon, and amorphous silicon. The material forming the first acoustic impedance layer is different from the material forming the second acoustic impedance layer.

27. The resonator according to any one of claims 1 to 8, 10 to 12, or 14 to 23, wherein: The electrode connection end of the bottom electrode is covered by a portion of the first acoustic impedance layer.

28. A bulk acoustic wave resonator assembly comprising: At least two resonators according to any one of claims 1 to 27, the at least two resonators sharing a same substrate.

29. A filter comprising the BAW resonator according to any one of claims 1 to 27, or the BAW resonator assembly according to claim 28.

30. An electronic device comprising the filter according to claim 29, or the BAW resonator according to any one of claims 1 to 27, or the BAW resonator assembly according to claim 28.

Images