Filter and method of manufacturing the same

Abstract

The present disclosure provides a filter and a manufacturing method thereof. The filter according to the present disclosure comprises: a center resonator; and at least one ring resonator arranged around the center resonator and electrically connected to the center resonator, wherein the center resonator and the at least one ring resonator each comprise a lower electrode, a piezoelectric layer and an upper electrode arranged in sequence in a vertical direction, and a sound reflection structure is arranged in the lower electrode of the center resonator and / or the at least one ring resonator. According to the filter and the manufacturing method thereof, by arranging multiple resonators of the filter in a nested manner, the integration of the filter can be improved and the volume of the filter can be reduced without increasing the process complexity. In addition, by arranging the sound reflection structure in the lower electrode of each resonator of the filter, the stability of the filter can be improved.

Description

Technical Field

[0001] This disclosure relates to the field of semiconductor technology, and in particular, to filters and methods of manufacturing the same. Background Technology

[0002] With the development of wireless communication applications, people have increasingly higher requirements for data transmission rates. Corresponding to these higher data transmission rates is the high utilization rate of spectrum resources and the increasing complexity of the spectrum. The increasing complexity of communication protocols places stringent requirements on various performance aspects of radio frequency (RF) systems. In the RF front-end module, RF filters play a crucial role, filtering out out-of-band interference and noise to meet the signal-to-noise ratio requirements of the RF system and communication protocols.

[0003] With the increasing demand for miniaturization and micro-miniaturization of communication devices, piezoelectric acoustic resonators have been proposed. In piezoelectric acoustic resonators, acoustic resonance modes are generated in the piezoelectric material, in which sound waves are converted into radio waves. Currently, bulk acoustic resonators (BAW), represented by thin-film bulk acoustic resonators (FBAR), have advantages such as small size, high operating frequency, and compatibility with integrated circuit (IC) manufacturing processes, and are therefore widely used in the construction of filters.

[0004] Figure 1 A schematic diagram of a prior art filter is shown. (e.g.) Figure 1 As shown, filters typically consist of multiple acoustic resonators arranged in a distributed manner. However, this arrangement results in a larger filter area, lower integration density, and consequently higher cost.

[0005] Furthermore, acoustic resonators ideally excite only longitudinal modes in the thickness direction (i.e., the vertical direction), such as TE modes, which are longitudinal sound waves with propagation vectors along the propagation direction. TE modes ideally propagate along the thickness direction of the piezoelectric layer in the acoustic resonator. However, in addition to the desired TE modes, transverse modes, such as Rayleigh-Lamb modes, also exist in acoustic resonators. Rayleigh-Lamb modes are sound waves with propagation vectors perpendicular to the direction of the TE modes. These transverse modes propagate horizontally along the surface of the piezoelectric layer of the acoustic resonator. Therefore, transverse modes adversely affect the quality factor (Q) of the acoustic resonator. Specifically, the energy of the Rayleigh-Lamb modes is lost at the transverse boundaries of the acoustic resonator, resulting in energy loss of the desired longitudinal modes, thus reducing the quality factor Q. Summary of the Invention

[0006] A brief overview of this disclosure is given below to provide a basic understanding of certain aspects thereof. However, it should be understood that this overview is not an exhaustive summary of this disclosure, nor is it intended to identify key or essential parts of this disclosure, nor is it intended to limit the scope of this disclosure. The purpose of this overview is merely to present some inventive concepts of this disclosure in a simplified form as a prelude to the more detailed description that follows.

[0007] The purpose of this disclosure is to provide a filter and a method for manufacturing the same that can overcome the defects present in the prior art described above.

[0008] According to one aspect of this disclosure, a filter is provided, comprising: a center resonator; and at least one ring resonator disposed around and electrically connected to the center resonator, wherein both the center resonator and the at least one ring resonator include a lower electrode, a piezoelectric layer and an upper electrode disposed sequentially in a vertical direction, and an acoustic reflection structure is provided in the lower electrode of the center resonator and / or the at least one ring resonator.

[0009] According to embodiments of this disclosure, an acoustic impedance mismatch structure is provided between the center resonator and at least one ring resonator, and between the at least one ring resonator and each other.

[0010] According to an embodiment of this disclosure, the acoustic impedance mismatch structure is an isolation groove.

[0011] According to embodiments of the present disclosure, the center resonator has a circular, elliptical, polygonal, or irregular shape, and at least one ring resonator is formed to have a ring shape corresponding to the shape of the center resonator.

[0012] According to embodiments of this disclosure, the acoustic reflection structure is a cavity or a Bragg reflector.

[0013] According to embodiments of this disclosure, a parallel and / or series electrical connection is formed between the center resonator and at least one ring resonator.

[0014] According to embodiments of this disclosure, the electrical connection between the center resonator and at least one ring resonator is achieved through an upper electrode and / or a lower electrode.

[0015] According to embodiments of this disclosure, the acoustic reflection structure is disposed in the middle of the upper surface and / or the middle of the lower surface and / or inside the lower electrode.

[0016] According to embodiments of this disclosure, a support structure for supporting the piezoelectric layer is provided at the center and / or at least one side of the lower electrode.

[0017] According to embodiments of the present disclosure, the support structure is made of a porous material selected from at least one of SiN, Al2O3, Al and SiO2.

[0018] According to embodiments of this disclosure, microstructures for reducing the propagation of sound waves in the horizontal direction perpendicular to the vertical direction are provided in the upper electrode and / or the lower electrode.

[0019] According to embodiments of this disclosure, the microstructure includes a bridge structure and / or an airfoil structure.

[0020] According to embodiments of this disclosure, the piezoelectric layer is doped with at least one of the following doping elements: Ti, Sc, Mg, Zr, Hf, Sb, Y, Sm, Eu, Er, Ta, Cr, B, Ga, and In.

[0021] According to another aspect of this disclosure, a method for manufacturing a filter is provided, the filter comprising: a center resonator; and at least one ring resonator disposed around and electrically connected to the center resonator, wherein both the center resonator and the at least one ring resonator include a lower electrode, a piezoelectric layer, and an upper electrode disposed sequentially along a vertical direction, the manufacturing method comprising: forming a lower electrode on a substrate; forming an acoustic reflection structure in the lower electrode of the center resonator and / or the at least one ring resonator; forming a piezoelectric layer covering the acoustic reflection structure on the lower electrode; and forming an upper electrode on the piezoelectric layer.

[0022] According to embodiments of the present disclosure, the manufacturing method further includes forming an acoustic impedance mismatch structure between the center resonator and at least one ring resonator and between the at least one ring resonator and each other.

[0023] According to an embodiment of this disclosure, the acoustic impedance mismatch structure is an isolation groove.

[0024] According to embodiments of this disclosure, the manufacturing method further includes forming a support structure for supporting the piezoelectric layer at the center and / or at least one side of the lower electrode.

[0025] According to embodiments of the present disclosure, the manufacturing method further includes forming microstructures in the upper electrode and / or lower electrode for reducing the propagation of sound waves in the horizontal direction perpendicular to the vertical direction.

[0026] According to embodiments of this disclosure, the microstructure includes a bridge structure and / or an airfoil structure.

[0027] According to the filter and manufacturing method disclosed herein, by arranging multiple resonators of the filter in a nested manner, the integration density of the filter can be improved and the size of the filter can be reduced without increasing the process complexity. Furthermore, the perimeter-to-area ratio of the resonators can be increased, thereby improving the heat dissipation performance of the resonators and the overall power capacity of the filter.

[0028] Furthermore, according to the filter and manufacturing method of the present disclosure, by providing an acoustic reflection structure in the lower electrode of the resonator constituting the filter, the stability of the filter can be improved without etching the substrate.

[0029] Furthermore, according to the filter and manufacturing method of the present disclosure, by forming an acoustic impedance mismatch structure between the resonators constituting the filter, the transmission of transverse waves can be reduced, which is beneficial to improving the quality factor.

[0030] Furthermore, according to the filter and manufacturing method of the present disclosure, by setting microstructures in the upper and / or lower electrodes of each resonator of the filter to reduce transverse acoustic wave propagation, the loss of resonant energy can be reduced, thereby improving the quality factor of the acoustic resonator. Attached Figure Description

[0031] The accompanying drawings are included to provide a further understanding of this disclosure and are incorporated in and form a part of this specification. The drawings illustrate embodiments of this disclosure and, together with the following description, serve to illustrate the principles of this disclosure.

[0032] Figure 1 A schematic diagram of a prior art filter is shown.

[0033] Figure 2A A plan view of a filter according to an embodiment of the present disclosure is shown.

[0034] Figure 2B The following is illustrated according to an embodiment of the present disclosure. Figure 2A The partial cross-sectional view taken by line A-A' in the figure.

[0035] Figure 2C The alternative embodiments according to this disclosure are shown along the path. Figure 2A The partial cross-sectional view taken by line A-A' in the figure.

[0036] Figure 3 A flowchart illustrating a method for manufacturing a filter according to an embodiment of the present disclosure is shown. Detailed Implementation

[0037] In this specification, it will also be understood that when a component is referred to relative to other components, such as “on,” “connected to,” or “coupled to” other components, that component may be directly disposed on, directly connected to, or directly coupled to that component, or there may be an intervening third component. Conversely, when a component is referred to in this specification relative to other components, such as “directly” on, directly connected to, or directly coupled to other components, there is no intervening component between them.

[0038] The present disclosure will now be described more fully below with reference to the accompanying drawings, in which various embodiments are illustrated. However, the present disclosure may be implemented in many different ways and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that the disclosure will be exhaustive and complete, and will fully convey the scope of the disclosure to those skilled in the art. The same reference numerals denote the same parts throughout the drawings. Furthermore, in the drawings, the thickness, proportions, and dimensions of parts are enlarged for clarity.

[0039] The terminology used herein is for descriptive purposes only and is not intended to be limiting. Unless the context clearly indicates otherwise, the terms “a,” “an,” “the,” and “at least one” as used herein are not intended to limit the quantity but are intended to include both singular and plural forms. For example, unless the context clearly indicates otherwise, “a component” has the same meaning as “at least one component.” “At least one” should not be construed as limited to the quantity “a.” “Or” means “and / or.” The term “and / or” includes any and all combinations of one or more of the associated listed items.

[0040] Furthermore, terms such as "below," "below," "above," and "upper" are used to describe the positional relationships of the components shown in the diagram. These terms can be relative concepts and are described based on the directions presented in the diagram.

[0041] Unless otherwise specified, all terms used herein, including technical and scientific terms, shall have the same meaning as commonly understood by one of ordinary skill in the art. Terms defined in commonly used dictionaries shall be interpreted as having the same meaning as in the relevant technical context, and shall not be construed as having a formal meaning in an idealized or overly formal sense unless expressly defined in the specification.

[0042] The meaning of “includes” or “contains” specifies a nature, quantity, step, operation, component, part, or combination thereof, but does not exclude other natures, quantities, steps, operations, components, parts, or combinations thereof.

[0043] This document describes embodiments with reference to cross-sectional views as idealized implementations. Thus, variations in shape relative to the illustrations are anticipated as a result of, for example, manufacturing techniques and / or tolerances. Therefore, the embodiments described herein should not be construed as limited to the specific shapes of the regions shown herein, but should include deviations in shape due to, for example, manufacturing processes. For example, regions shown or described as flat may typically have rough and / or non-linear characteristics. Furthermore, acute angles shown may be rounded. Therefore, the regions shown in the figures are schematic in nature, and their shapes are not intended to show precise shapes of the regions and are not intended to limit the scope of the claims.

[0044] In the following description, exemplary embodiments according to the present disclosure will be described with reference to the accompanying drawings.

[0045] Figure 2A A plan view of a filter 200 according to an embodiment of the present disclosure is shown. Figure 2B The following is illustrated according to an embodiment of the present disclosure. Figure 2A The partial cross-sectional view taken by line A-A' in the figure.

[0046] like Figure 2A As shown, the filter 200 according to an embodiment of the present disclosure includes a substrate 210 (see...). Figure 2B A central resonator 201 is fabricated on the central resonator 201, and a first ring resonator 202, a second ring resonator 203, a third ring resonator 204, and a fourth ring resonator 205 are arranged around the central resonator 201. According to embodiments of this disclosure, such as... Figure 2A As shown, the first ring resonator 202, the second ring resonator 203, the third ring resonator 204 and the fourth ring resonator 205 are arranged in a nested manner around the central resonator 201.

[0047] According to embodiments of the present disclosure, the first ring resonator 202, the second ring resonator 203, the third ring resonator 204 and the fourth ring resonator 205 can be electrically connected to the center resonator 201 in parallel or in series.

[0048] although Figure 2A The diagram shows a filter 200 comprising four ring resonators 202 to 205 arranged around a central resonator 201, but this disclosure is not limited thereto. According to embodiments of this disclosure, the number of ring resonators arranged around the central resonator 201 can be any number greater than or equal to 1.

[0049] Furthermore, despite Figure 2AThe diagram shows that the central resonator 201 and the first to fourth ring resonators 202 to 205 all have a pentagonal shape, but the present disclosure is not limited thereto. According to embodiments of the present disclosure, the central resonator 201 may have any shape among circles, ellipses, polygons, or irregular shapes.

[0050] According to embodiments of this disclosure, the first to fourth ring resonators 202 to 205 can all be formed as rings corresponding to the shape of the central resonator 201. For example, as Figure 2A As shown, the first to fourth ring resonators 202 to 205 are all formed with rings corresponding to pentagons. Alternatively, the first to fourth ring resonators 202 to 205 may also be formed with rings having a shape inconsistent with that of the central resonator 201. Alternatively, the first to fourth ring resonators 202 to 205 may have rings with shapes that do not correspond to each other. According to other embodiments of this disclosure, the central resonator 201 and adjacent resonators among the first to fourth ring resonators 202 to 205 have non-corresponding shapes, which can reduce the parasitic effects of the resonators and further improve the quality factor.

[0051] like Figure 2A As shown, according to an embodiment of the present disclosure, an acoustic impedance mismatch structure 206 for realizing acoustic impedance mismatch is provided between the center resonator 201 and the first ring resonator 202, and between the first to fourth ring resonators 202 to 205 and each other. According to an embodiment of the present disclosure, the acoustic impedance mismatch structure 206 may have an isolation groove configuration. According to an embodiment of the present disclosure, the width of the isolation groove may be in the range of 1 μm to 50 μm, preferably 1 μm, 2 μm, 3 μm, 4 μm, and 5 μm.

[0052] According to embodiments of this disclosure, the filter 200 includes a center resonator 201 and ring resonators 202 to 205 surrounding the center resonator, which are arranged in a nested manner, compared to... Figure 1 The prior art filters shown herein, with the same number of resonators, occupy less area, increase integration density, and have a smaller overall filter volume. Furthermore, they can increase the perimeter-to-area ratio of the resonators, thereby improving the heat dissipation performance of the resonators and the overall power capacity of the filter. In addition, according to embodiments of this disclosure, by employing a nested arrangement with isolation slots between the central resonator and each ring resonator—that is, with isolation slots between adjacent resonators—the propagation of transverse acoustic waves along the filter surface can be reduced, which is beneficial for improving the quality factor Q of the resonators, thereby improving the filter performance.

[0053] It should be noted that, for the sake of brevity, Figure 2BOnly a partial cross-sectional view of the cross-section including the center resonator 201 and the first ring resonator 202 is shown. According to embodiments of this disclosure, the second ring resonator 203, the third ring resonator 204, and the fourth ring resonator 205 may have the same configuration as the first ring resonator 202.

[0054] like Figure 2B As shown, both the center resonator 201 and the first ring resonator 202 include a lower electrode 230, a piezoelectric layer 240 and an upper electrode 250 arranged sequentially along the vertical direction, i.e. the thickness direction of the filter 200.

[0055] In this paper, since the central resonator and each ring resonator have the same configuration, namely, each includes a lower electrode, a piezoelectric layer, and an upper electrode arranged sequentially in the vertical direction, the same reference numerals are used to denote the corresponding components included in the different resonators for ease of description. For example, in Figure 2B In the figure, reference numeral 230 indicates the lower electrode included in the center resonator 201 and the first ring resonator 202 respectively, without further detailed distinction.

[0056] According to embodiments of this disclosure, the substrate 210 may be a semiconductor substrate such as a silicon substrate, a silicon carbide substrate, or a gallium arsenide substrate.

[0057] like Figure 2B As shown, the lower electrode 230 is disposed on the substrate 210. According to embodiments of the present disclosure, the lower electrode 230 may include a conductive material. For example, according to embodiments of the present disclosure, the conductive material may include, but is not limited to, molybdenum (Mo), tungsten (W), aluminum (Al), platinum / titanium (Pt / Ti) stacks or gold / chromium (Au / Cr) stacks.

[0058] like Figure 2B As shown, according to an embodiment of the present disclosure, an acoustic reflection structure 220 may be provided in the lower electrode 230 of the center resonator 201 and the first ring resonator 202. According to an embodiment of the present disclosure, the acoustic reflection structure 220 is used to reflect the energy of sound waves in the vertical direction, thereby reducing energy loss and improving the quality factor Q of the resonator.

[0059] although Figure 2B The diagram shows the acoustic reflection structure 220 formed in the upper surface of the lower electrode 230, but the present disclosure is not limited thereto. According to embodiments of the present disclosure, the acoustic reflection structure 220 may also be formed in the lower surface of the lower electrode 230, or inside the lower electrode 230.

[0060] Furthermore, despite Figure 2BThe acoustic reflection structure 220 is shown in the form of a cavity, but this disclosure is not limited thereto. According to embodiments of this disclosure, the acoustic reflection structure 220 can also be other types of acoustic reflection structures, such as a Bragg reflector. In particular, in embodiments where the acoustic reflection structure 220 is configured as a Bragg reflector, the drift problem of the resonant frequency changing with temperature can be improved, while also possessing strong resistance to mechanical vibration.

[0061] like Figure 2B As shown, according to an embodiment of the present disclosure, a support structure 260 is provided at the center of the lower electrode 230, for example in the acoustic reflection structure 220. Furthermore, according to an embodiment of the present disclosure, a support structure 270 for supporting the piezoelectric layer may also be provided on at least one side of the lower electrode 230. According to an embodiment of the present disclosure, support structures 260 and 270 are used to support the piezoelectric layer 240 formed on the lower electrode 230.

[0062] According to embodiments of this disclosure, support structures 260 and 270 may be formed of at least one of silicon nitride (SiN), aluminum oxide (Al2O3), and aluminum (Al).

[0063] Furthermore, according to embodiments of this disclosure, support structures 260 and 270 can also serve as temperature compensation components. In this respect, the frequency temperature coefficients of support structures 260 and 270, as temperature compensation components, together with the frequency temperature coefficients of the lower electrode 230, piezoelectric layer 240, and upper electrode 250, determine the frequency temperature coefficient of the resonator. Specifically, the frequency temperature coefficients of support structures 260 and 270 can be opposite to the frequency temperature coefficient of piezoelectric layer 240. For example, if piezoelectric layer 240 has a negative frequency temperature coefficient, temperature compensation component 260 can have a positive frequency temperature coefficient. When aluminum nitride (AlN) is used to form piezoelectric layer 240, the materials forming support structures 260 and 270 can be tellurium oxide (TeO), silicon oxide (SiO2), or combinations thereof.

[0064] Furthermore, according to embodiments of this disclosure, the support structures 260 and 270 may also be made of a porous material formed from the material described above, thereby improving the sound reflection effect in the vertical direction.

[0065] Furthermore, despite Figure 2B The intermediate support structure 260 is shown as a single support structure disposed at the center of the acoustic reflection structure 220 in the lower electrode 230, but the present disclosure is not limited thereto. According to embodiments of the present disclosure, multiple support structures 260 may exist, which may be arranged in an array within the acoustic reflection structure 220 in the lower electrode 230.

[0066] like Figure 2BAs shown, the piezoelectric layer 240 can be disposed on the lower electrode 230 to cover the acoustic reflection structure 220. According to embodiments of this disclosure, the piezoelectric layer 240 can be made of a piezoelectric material, which can be selected from inorganic piezoelectric (single crystal or polycrystalline) materials or organic piezoelectric materials. Examples of piezoelectric materials may include: wurtzite structures, such as aluminum nitride (AlN) and zinc oxide (ZnO); perovskite structures, such as BaTiO3, Pb(Ti,Zr)O3, Li(Nb,Ta)O3, and (K,Na)NbO3; and organic piezoelectric materials, such as polyvinylidene fluoride (PVDF).

[0067] Furthermore, according to embodiments of this disclosure, the piezoelectric layer 240 may be doped with doping elements for adjusting the electromechanical coupling coefficient and quality factor of the piezoelectric layer 240. According to embodiments of this disclosure, the doping element for adjusting the electromechanical coupling coefficient may be selected from at least one of Ti, Sc, Mg, Zr, Hf, Sb, Y, Sm, Eu, Er, Ta, and Cr. Furthermore, according to embodiments of this disclosure, the doping element for adjusting the quality factor may be selected from at least one of B, Ga, and In.

[0068] According to embodiments of this disclosure, the piezoelectric layer 240 may be doped with rare earth elements such as Sc, and the doping ratio may be from 1% to 20%.

[0069] like Figure 2B As shown, the upper electrode 250 can be disposed on the piezoelectric layer 240. Similar to the lower electrode 230, according to embodiments of this disclosure, the upper electrode 250 may include a conductive material. For example, according to embodiments of this disclosure, the conductive material may include, but is not limited to, molybdenum (Mo), tungsten (W), aluminum (Al), platinum / titanium (Pt / Ti) stacks or gold / chromium (Au / Cr) stacks.

[0070] According to embodiments of this disclosure, the lower electrode 230 and the upper electrode 250 can provide an oscillating electric field together in the vertical direction when electrically excited.

[0071] although Figure 2B The diagram shows that the lower electrode 230 of the center resonator 201 is spaced apart from the lower electrode 230 of the first ring resonator 202, and the upper electrode 250 of the center resonator 201 is spaced apart from the upper electrode 250 of the first ring resonator 202. However, those skilled in the art will recognize that the electrical connection between the center resonator 201 and the first to fourth ring resonators 202 to 205 mentioned above can be achieved through the lower electrode 230 and / or the upper electrode 250. That is, the lower electrodes 230 and / or the upper electrodes 250 of different resonators 201 to 205 can be partially connected to achieve the electrical connection between the ring resonator and the center resonator.

[0072] For each of the central resonator 201 and the first to fourth ring resonators 202 to 205, the area where the lower electrode 230, the piezoelectric layer 240, and the upper electrode 250 overlap with the acoustic reflection structure 220 constitutes the effective resonant region of the resonator.

[0073] like Figure 2B As shown, according to an embodiment of this disclosure, a microstructure 280 for reducing the propagation of sound waves in the horizontal direction perpendicular to the vertical direction is provided in the upper electrode 250. For example... Figure 2B As shown, according to embodiments of this disclosure, the microstructure 280 may have a bridge structure and an airfoil structure.

[0074] although Figure 2B The diagram shows a microstructure 280 disposed in the upper electrode 250, but this disclosure is not limited thereto. In other embodiments of this disclosure, the lower electrode 230 may also have a microstructure 280 disposed therein, which will be referred to... Figure 2C A more detailed description would follow. Furthermore, although... Figure 2B The microstructure 280 is shown to have a bridge structure and an airfoil structure, but the present disclosure is not limited thereto. In other embodiments of the present disclosure, the microstructure 280 may also have structures such as cavities, recesses and / or protrusions, as long as they can suppress the propagation of sound waves in the horizontal direction.

[0075] Furthermore, despite Figure 2B The diagram shows a microstructure 280 disposed in the lower surface of the upper electrode 250, but this disclosure is not limited thereto. In other embodiments of this disclosure, the microstructure 280 may also be disposed in or inside the upper surface of the upper electrode 250.

[0076] According to embodiments of this disclosure, the microstructure 280 can provide an acoustic impedance mismatch at the boundary of the effective resonant region. This acoustic impedance mismatch causes acoustic wave reflection at the boundary, preventing the acoustic waves from propagating outside the effective resonant region and thus avoiding energy loss. By avoiding this energy loss, the microstructure 280 can improve the quality factor of the resonator.

[0077] Furthermore, according to an alternative embodiment of this disclosure, the support structure 270 for supporting the piezoelectric layer disposed on at least one side of the lower electrode 230 can be omitted, and only the support structure 260 formed in the acoustic reflection structure 220 is used to support the piezoelectric layer 240. Figure 2C The alternative embodiments according to this disclosure are shown along the path. Figure 2A The partial cross-sectional view taken by line A-A' in the figure.

[0078] like Figure 2C As shown, according to an alternative embodiment of this disclosure, the lower electrode 230 is omitted. Figure 2BThe support structure 270 is shown. Furthermore, according to an alternative embodiment of this disclosure, similar to the upper electrode 250, a microstructure 290 for reducing the propagation of sound waves in the horizontal direction perpendicular to the vertical direction is provided in the lower electrode 230. For example... Figure 2C As shown, according to an alternative embodiment of this disclosure, the microstructure 290 may have a bridge structure and an airfoil structure.

[0079] Furthermore, despite Figure 2C The microstructure 290 is shown to have a bridge structure and an airfoil structure, but the present disclosure is not limited thereto. In other embodiments of the present disclosure, the microstructure 290 may also have structures such as cavities, recesses and / or protrusions, as long as they can suppress the propagation of sound waves in the horizontal direction.

[0080] Furthermore, despite Figure 2C The diagram shows a microstructure 290 disposed in the lower surface of the lower electrode 230, but this disclosure is not limited thereto. In other embodiments of this disclosure, the microstructure 290 may also be disposed in or inside the upper surface of the lower electrode 230.

[0081] Figure 3 A flowchart of a filter manufacturing method 300 according to an embodiment of the present disclosure is shown.

[0082] like Figure 3 As shown in the solid-line box, the method 300 for manufacturing an acoustic resonator according to an embodiment of the present disclosure includes the following steps:

[0083] S310: Form the lower electrode on the substrate;

[0084] S320: An acoustic reflection structure is formed in the lower electrode of the center resonator and / or at least one ring resonator;

[0085] S330: A piezoelectric layer covering the acoustic reflection structure is formed on the lower electrode; and

[0086] S340: An upper electrode is formed on the piezoelectric layer.

[0087] Preferably, such as Figure 3 As shown in the dashed box, according to an embodiment of this disclosure, the manufacturing method 300 may further include the following steps:

[0088] S325: A support structure for supporting the piezoelectric layer is formed at the center and / or at least one side of the lower electrode;

[0089] S345: Forming microstructures in the upper and / or lower electrodes to reduce the propagation of acoustic waves in the horizontal direction perpendicular to the vertical direction; and

[0090] S350: An acoustic impedance mismatch structure is formed between the center resonator and at least one ring resonator, and between the at least one ring resonator and each other.

[0091] The above steps of the filter manufacturing method according to the embodiments of this disclosure can be implemented by semiconductor processes known to those skilled in the art, such as deposition, etching, sputtering, etc. Therefore, the specific process details are not described in more detail here.

[0092] According to the filter and manufacturing method disclosed herein, by arranging multiple resonators of the filter in a nested manner, the integration density of the filter can be improved and the size of the filter can be reduced without increasing the process complexity. Furthermore, the perimeter-to-area ratio of the resonators can be increased, thereby improving the heat dissipation performance of the resonators and the overall power capacity of the filter.

[0093] Furthermore, according to the filter and manufacturing method of the present disclosure, by providing an acoustic reflection structure in the lower electrode of the resonator constituting the filter, the stability of the filter can be improved without etching the substrate.

[0094] Furthermore, according to the filter and manufacturing method of the present disclosure, by forming an acoustic impedance mismatch structure between the resonators constituting the filter, the transmission of transverse waves can be reduced, which is beneficial to improving the quality factor.

[0095] Furthermore, according to the filter and manufacturing method of the present disclosure, by setting microstructures in the upper and / or lower electrodes of each resonator of the filter to reduce transverse acoustic wave propagation, the loss of resonant energy can be reduced, thereby improving the quality factor of the acoustic resonator.

[0096] Although this disclosure has been described with reference to exemplary embodiments thereof, those skilled in the art will understand that various modifications and variations may be made without departing from the spirit and scope of this disclosure as set forth in the claims.

Claims

1. A filter, comprising: Center resonator; as well as At least one ring resonator is arranged around the central resonator and electrically connected to the central resonator. The central resonator and the at least one ring resonator each include a lower electrode, a piezoelectric layer, and an upper electrode arranged sequentially in a vertical direction. An acoustic reflection structure is provided in the lower electrode of the central resonator and / or the at least one ring resonator, and an acoustic impedance mismatch structure, which is an isolation groove, is provided between the central resonator and the at least one ring resonator and between the at least one ring resonator and each other.

2. The filter according to claim 1, in, The central resonator has a circular, elliptical, polygonal, or irregular shape, and The at least one ring resonator is formed as a ring corresponding to the shape of the center resonator.

3. The filter according to claim 1, wherein, The acoustic reflection structure is a cavity or a Bragg reflector.

4. The filter according to claim 1, wherein, A parallel and / or series electrical connection is formed between the center resonator and the at least one ring resonator.

5. The filter according to claim 4, wherein, The electrical connection between the center resonator and the at least one ring resonator is achieved through the upper electrode and / or the lower electrode.

6. The filter according to claim 1, wherein, The acoustic reflection structure is disposed in the upper surface and / or lower surface and / or inside the lower electrode.

7. The filter according to claim 1, wherein, A support structure for supporting the piezoelectric layer is provided at the center and / or at least one side of the lower electrode.

8. The filter according to claim 7, wherein, The support structure is made of a porous material selected from at least one of SiN, Al2O3, Al and SiO2.

9. The filter according to claim 1, wherein, Microstructures for reducing the propagation of sound waves in the horizontal direction perpendicular to the vertical direction are provided in the upper electrode and / or the lower electrode.

10. The filter according to claim 9, wherein, The microstructures include bridge-like structures and / or airfoil-like structures.

11. The filter according to claim 1, wherein, The piezoelectric layer is doped with at least one of the following doping elements: Ti, Sc, Mg, Zr, Hf, Sb, Y, Sm, Eu, Er, Ta, Cr, B, Ga, and In.

12. A method for manufacturing a filter, The filter includes: Center resonator; as well as At least one ring resonator is arranged around the central resonator and electrically connected to the central resonator. The central resonator and the at least one ring resonator each include a lower electrode, a piezoelectric layer, and an upper electrode arranged sequentially along the vertical direction. The manufacturing method includes: The lower electrode is formed on the substrate; An acoustic reflection structure is formed in the lower electrode of the center resonator and / or the at least one ring resonator, and an acoustic impedance mismatch structure is formed between the center resonator and the at least one ring resonator and between the at least one ring resonator and each other, the acoustic impedance mismatch structure being an isolation groove. The piezoelectric layer covering the acoustic reflection structure is formed on the lower electrode; and The upper electrode is formed on the piezoelectric layer.

13. The manufacturing method according to claim 12, further comprising: A support structure for supporting the piezoelectric layer is formed at the center and / or at least one side of the lower electrode.

14. The manufacturing method according to claim 12, further comprising: Microstructures are formed in the upper electrode and / or the lower electrode to reduce the propagation of sound waves in the horizontal direction perpendicular to the vertical direction.

15. The manufacturing method according to claim 14, wherein, The microstructures include bridge-like structures and / or airfoil-like structures.

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