CN116366024A - Filter and method for manufacturing the same - Google Patents

Filter and method for manufacturing the same Download PDF

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Publication number
CN116366024A
CN116366024A CN202111625208.9A CN202111625208A CN116366024A CN 116366024 A CN116366024 A CN 116366024A CN 202111625208 A CN202111625208 A CN 202111625208A CN 116366024 A CN116366024 A CN 116366024A
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China
Prior art keywords
resonator
filter
lower electrode
present disclosure
center
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Inventor
吴明
杨清华
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Suzhou Huntersun Electronics Co Ltd
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Suzhou Huntersun Electronics Co Ltd
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Priority to CN202111625208.9A priority Critical patent/CN116366024A/en
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/46—Filters
    • H03H9/54—Filters comprising resonators of piezoelectric or electrostrictive material
    • H03H9/56—Monolithic crystal filters
    • H03H9/564—Monolithic crystal filters implemented with thin-film techniques
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
    • H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
    • H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/46—Filters
    • H03H9/54—Filters comprising resonators of piezoelectric or electrostrictive material
    • H03H9/58—Multiple crystal filters
    • H03H9/582—Multiple crystal filters implemented with thin-film techniques
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
    • H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
    • H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
    • H03H2003/023—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks the resonators or networks being of the membrane type

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  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)

Abstract

The present disclosure provides a filter and a method of manufacturing the same. The filter according to the present disclosure includes: a center resonator; and at least one ring resonator disposed around and electrically connected to the center resonator, wherein each of the center resonator and the at least one ring resonator includes a lower electrode, a piezoelectric layer, and an upper electrode sequentially disposed in a vertical direction, and an acoustic reflection structure is disposed in the center resonator and/or the lower electrode of the at least one ring resonator. According to the filter and the manufacturing method thereof of the present disclosure, by disposing a plurality of resonators of the filter in a nested manner, it is possible to improve the integration level of the filter and reduce the volume of the filter without increasing the complexity of the process. In addition, by providing an acoustic reflection structure in the lower electrode of each resonator of the filter, the stability of the filter can be improved.

Description

Filter and method for manufacturing the same
Technical Field
The present disclosure relates to the field of semiconductor technology, and in particular, to a filter and a method of manufacturing the same.
Background
With the development of wireless communication applications, there is an increasing demand for data transmission rates, corresponding to which is high utilization of spectrum resources and complexity of spectrum. The complexity of the communication protocol puts strict demands on various performances of the radio frequency system, and in the radio frequency front-end module, the radio frequency filter plays a crucial role, and can filter out-of-band interference and noise to meet the requirements of the radio frequency system and the communication protocol on signal-to-noise ratio.
With the need for miniaturization and microminiaturization of communication devices, acoustic resonators based on piezoelectric effect are proposed. In an acoustic resonator based on the piezoelectric effect, an acoustic resonance mode is generated in a piezoelectric material, in which an acoustic wave is converted into a radio wave. Currently, bulk acoustic resonators (BAWs), typified by thin Film Bulk Acoustic Resonators (FBARs), have advantages of small size, high operating frequency, compatibility with Integrated Circuit (IC) manufacturing processes, and the like, and thus are widely used for constructing filters.
Fig. 1 shows a schematic diagram of a prior art filter. As shown in fig. 1, the filter typically includes a plurality of acoustic resonators arranged in a distributed manner. However, such an arrangement results in a larger area occupied by the filter and a lower integration, thus resulting in higher costs.
Furthermore, the acoustic resonator desirably excites only longitudinal modes in the thickness direction (i.e., the vertical direction), such as TE modes, which are longitudinal acoustic waves having a propagation vector along the propagation direction. The TE mode desirably propagates along the thickness direction of the piezoelectric layer in the acoustic resonator. However, in addition to the desired TE mode, there are also transverse modes in the acoustic resonator, such as Rayleigh-Lamb modes. The Rayleigh-Lamb mode is an acoustic wave whose propagation vector is perpendicular to the direction of the TE mode. These transverse modes propagate in the horizontal direction along the piezoelectric layer surface of the acoustic resonator. Therefore, the transverse mode adversely affects the quality factor (Q) of the acoustic resonator. In particular, the energy of the Rayleigh-Lamb mode is lost at the lateral boundaries of the acoustic resonator, resulting in the energy loss of the desired longitudinal mode, thus lowering the quality factor Q.
Disclosure of Invention
The following presents a simplified summary of the disclosure in order to provide a basic understanding of some aspects of the disclosure. However, it should be understood that this summary is not an exhaustive overview of the disclosure, nor is it intended to identify key or critical elements of the disclosure, nor is it intended to limit the scope of the disclosure. This summary is provided merely to introduce a selection of concepts in a simplified form that are further described below in the form of a more detailed description.
It is an object of the present disclosure to provide a filter and a method of manufacturing the same that can overcome the drawbacks of the prior art described above.
According to one aspect of the present disclosure, there is provided a filter including: a center resonator; and at least one ring resonator disposed around and electrically connected to the center resonator, wherein each of the center resonator and the at least one ring resonator includes a lower electrode, a piezoelectric layer, and an upper electrode sequentially disposed in a vertical direction, and an acoustic reflection structure is disposed in the center resonator and/or the lower electrode of the at least one ring resonator.
According to embodiments of the present disclosure, acoustic impedance mismatch structures are provided between the center resonator and the at least one ring resonator and between each other.
According to an embodiment of the present disclosure, the acoustic impedance mismatch structure is an isolation groove.
According to an embodiment of the present disclosure, the central resonator has a circular, elliptical, polygonal or irregularly shaped shape, and at least one ring resonator is formed to have a ring shape corresponding to the shape of the central resonator.
According to an embodiment of the present disclosure, the acoustic reflecting structure is a cavity or a bragg reflector.
According to an embodiment of the present disclosure, a parallel and/or series electrical connection is formed between the central resonator and the at least one ring resonator.
According to an embodiment of the present disclosure, the electrical connection between the central resonator and the at least one ring resonator is achieved by an upper electrode and/or a lower electrode.
According to embodiments of the present disclosure, the acoustic reflecting structure is provided in and/or in the upper surface and/or the lower surface of the lower electrode.
According to an embodiment of the present disclosure, a support structure for supporting the piezoelectric layer is provided at the center and/or at least one side of the lower electrode.
According to an embodiment of the present disclosure, the support structure is composed of a material selected from SiN, al 2 O 3 Al and SiO 2 At least one of the porous materials.
According to an embodiment of the present disclosure, a microstructure for reducing propagation of sound waves in a horizontal direction perpendicular to a vertical direction is provided in the upper electrode and/or the lower electrode.
According to embodiments of the present disclosure, the microstructures include bridge structures and/or wing structures.
According to an embodiment of the present 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.
According to another aspect of the present disclosure, there is provided a method of manufacturing a filter including: a center resonator; and at least one ring resonator disposed around the center resonator and electrically connected to the center resonator, wherein the center resonator and the at least one ring resonator each include a lower electrode, a piezoelectric layer, and an upper electrode sequentially disposed in a vertical direction, the manufacturing method including: forming a lower electrode on a substrate; forming an acoustic reflecting structure in the lower electrode of the central 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.
According to an embodiment of the present disclosure, the manufacturing method further includes: 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.
According to an embodiment of the present disclosure, the acoustic impedance mismatch structure is an isolation groove.
According to an embodiment of the present disclosure, the manufacturing method further includes: a support structure for supporting the piezoelectric layer is formed at the center and/or at least one side of the lower electrode.
According to an embodiment of the present disclosure, the manufacturing method further includes: microstructures for reducing propagation of acoustic waves in a horizontal direction perpendicular to the vertical direction are formed in the upper electrode and/or the lower electrode.
According to embodiments of the present disclosure, the microstructures include bridge structures and/or wing structures.
According to the filter and the manufacturing method thereof of the present disclosure, by arranging a plurality of resonators of the filter in a nested manner, the integration level of the filter can be improved and the volume of the filter can be reduced without increasing the process complexity, and the area ratio of the circumference of the resonators can also be increased, thereby improving the heat dissipation performance of the resonators and the overall power capacity of the filter.
Further, according to the filter and the method of manufacturing the same of the present disclosure, by providing the acoustic reflection structure in the lower electrode of the resonator constituting the filter, the substrate does not need to be etched, and the stability of the filter can be improved.
Further, according to the filter and the method of manufacturing the same of the present disclosure, by forming an acoustic impedance mismatch structure between resonators constituting the filter, the transmission of transverse waves can be reduced, which is advantageous in improving the quality factor.
Further, according to the filter and the method of manufacturing the same of the present disclosure, by providing a microstructure in the upper electrode and/or the lower electrode of each resonator of the filter to reduce lateral acoustic wave propagation, loss of resonance energy can be reduced, thereby improving the quality factor of the acoustic resonator.
Drawings
The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the present disclosure and, together with the description, serve to explain the principles of the disclosure.
Fig. 1 shows a schematic diagram of a prior art filter.
Fig. 2A shows a plan view of a filter according to an embodiment of the present disclosure.
FIG. 2B illustrates a partial cross-sectional view taken along line A-A' in FIG. 2A, according to an embodiment of the present disclosure.
Fig. 2C illustrates a partial cross-sectional view taken along line A-A' in fig. 2A, according to an alternative embodiment of the present disclosure.
Fig. 3 shows a flowchart of a method of manufacturing a filter according to an embodiment of the present disclosure.
Detailed Description
In this specification, it will also be understood that when an element is referred to as being "on," "connected to" or "coupled to" with respect to other elements, it can be directly on, connected or coupled directly to the element, or intervening third elements may also be present. In contrast, when an element is referred to in the present specification as being "directly on," "directly connected to" or "directly coupled to" another element, there are no intervening elements present therebetween.
The present disclosure now will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments are shown. The present disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Like numbers refer to like elements throughout. Also, in the drawings, the thickness, ratio, and size of the parts are exaggerated for clarity of illustration.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, unless the context clearly indicates otherwise, "a," "an," "the," and "at least one" are not meant to limit the amount, but are intended to include both the singular and the plural. For example, unless the context clearly indicates otherwise, the meaning of "a component" is the same as "at least one component". The "at least one" should not be construed as limited to the number "one". "or" means "and/or". The term "and/or" includes any and all combinations of one or more of the associated listed items.
The terms "lower", "upper" and the like are used to describe the positional relationship of the components shown in the drawings. These terms may be relative concepts and are described based on the orientation presented in the figures.
Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms as defined in commonly used dictionaries should be interpreted as having the same meaning as that of the relevant art context and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
The meaning of "comprising" or "including" indicates a property, quantity, step, operation, component, element, or combination thereof, but does not preclude other properties, quantities, steps, operations, components, elements, or combinations thereof.
Embodiments are described herein with reference to cross-sectional illustrations that are idealized embodiments. Thus, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments described herein should not be construed as limited to the particular shapes of regions as illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, a region shown or described as being flat may typically have rough and/or nonlinear features. Also, the acute angles shown may be rounded. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shape of a region and are not intended to limit the scope of the claims.
Hereinafter, exemplary embodiments according to the present disclosure will be described with reference to the accompanying drawings.
Fig. 2A shows a plan view of a filter 200 according to an embodiment of the present disclosure. FIG. 2B illustrates a partial cross-sectional view taken along line A-A' in FIG. 2A, according to an embodiment of the present disclosure.
As shown in fig. 2A, a filter 200 according to an embodiment of the present disclosure includes a center resonator 201 prepared on a substrate 210 (see fig. 2B), and first, second, third, and fourth ring resonators 202, 203, 204, and 205 disposed around the center resonator 201. According to an embodiment of the present disclosure, as shown in fig. 2A, a first ring resonator 202, a second ring resonator 203, a third ring resonator 204, and a fourth ring resonator 205 are disposed around a center resonator 201 in sequence in a nested fashion.
According to an embodiment 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 may be electrically connected to the center resonator 201 in parallel or in series.
Although the filter 200 is shown in fig. 2A to include four ring resonators 202 to 205 disposed around the center resonator 201, the present disclosure is not limited thereto. According to embodiments of the present disclosure, the number of ring resonators disposed around the center resonator 201 may be any number greater than or equal to 1.
Further, although the center resonator 201 and the first to fourth ring resonators 202 to 205 are each shown in fig. 2A to have a pentagonal shape, the present disclosure is not limited thereto. According to embodiments of the present disclosure, the center resonator 201 may have any of a circular shape, an elliptical shape, a polygonal shape, or a special shape.
According to an embodiment of the present disclosure, the first to fourth ring resonators 202 to 205 may each be formed to have a ring shape corresponding to the shape of the center resonator 201. For example, as shown in fig. 2A, each of the first to fourth ring resonators 202 to 205 is formed to have a ring shape corresponding to a pentagon. Alternatively, the first to fourth ring resonators 202 to 205 may also be each formed to have a ring shape that does not conform to the shape of the center resonator 201. Alternatively, the first to fourth ring resonators 202 to 205 may have rings that do not correspond in shape to each other. According to other embodiments of the present disclosure, the center resonator 201 and adjacent resonators among the first to fourth ring resonators 202 to 205 have non-corresponding shapes, which can reduce parasitic effects of the resonators, thereby further improving the quality factor.
As shown in fig. 2A, 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, according to an embodiment of the present disclosure. According to embodiments of the present disclosure, the acoustic impedance mismatch structure 206 may have the configuration of isolation grooves. According to an embodiment of the present disclosure, the width of the isolation trench may be in the range of 1 μm to 50 μm, preferably 1 μm, 2 μm, 3 μm, 4 μm and 5 μm.
According to the embodiment of the present disclosure, the center resonator 201 and the ring resonators 202 to 205 surrounding the center resonator included in the filter 200 are configured in a nested manner, and compared with the prior art filter as shown in fig. 1, the occupied area is reduced, the integration level is improved, and the overall volume of the filter is smaller, and also the peripheral area ratio of the resonators can be increased, thereby improving the heat radiation performance of the resonators and the overall power capacity of the filter. In addition, according to the embodiment of the disclosure, by arranging the isolation grooves between the center resonator and each ring resonator in a nested manner, that is, arranging the isolation grooves between adjacent resonators, propagation of transverse sound waves along the surface of the filter can be reduced, which is beneficial to improving the quality factor Q of the resonators, thereby improving the performance of the filter.
It should be noted that for simplicity, only a partial cross-sectional view of a cross-section including the center resonator 201 and the first ring resonator 202 is shown in fig. 2B. According to an embodiment of the present 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.
As shown in fig. 2B, the center resonator 201 and the first ring resonator 202 each include a lower electrode 230, a piezoelectric layer 240, and an upper electrode 250, which are sequentially disposed in the vertical direction, i.e., the thickness direction of the filter 200.
Herein, since the center resonator and each ring resonator have the same configuration, i.e., each includes a lower electrode, a piezoelectric layer, and an upper electrode, which are sequentially disposed in the vertical direction. Accordingly, for convenience of description, corresponding parts included in different resonators are denoted by the same reference numerals. For example, in fig. 2B, reference numeral 230 denotes lower electrodes respectively included in the center resonator 201 and the first ring resonator 202 without further detailed distinction.
According to embodiments of the present disclosure, the substrate 210 may be a semiconductor substrate such as a silicon substrate, a silicon carbide substrate, a gallium arsenide substrate, or the like.
As shown in fig. 2B, a lower electrode 230 is disposed on the substrate 210. According to an embodiment of the present disclosure, the lower electrode 230 may include a conductive material. For example, in accordance with 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.
As shown in fig. 2B, in accordance with an embodiment of the present disclosure, an acoustic reflection structure 220 may be disposed in the center resonator 201 and the lower electrode 230 of the first ring resonator 202. According to an embodiment of the present disclosure, the acoustic reflection structure 220 serves to reflect energy of an acoustic wave in a vertical direction, thereby reducing energy loss and improving the quality factor Q of the resonator.
Although fig. 2B illustrates that the sound reflecting structure 220 is formed in the upper surface of the lower electrode 230, the present disclosure is not limited thereto. The acoustic reflection structure 220 may also be formed in the lower surface of the lower electrode 230 or in the inside of the lower electrode 230 according to an embodiment of the present disclosure.
Further, although fig. 2B shows the acoustic reflecting structure 220 in the form of a cavity, the present disclosure is not limited thereto. The acoustic reflecting structure 220 may also be other types of acoustic reflecting structures, such as a bragg reflector, according to embodiments of the present disclosure. In particular, in embodiments where the acoustic reflecting structure 220 is configured as a Bragg reflector, the problem of drift in resonant frequency as a function of temperature may be ameliorated while providing greater resistance to mechanical vibration.
As shown in fig. 2B, a support structure 260 is provided in the center of the lower electrode 230, for example in the acoustic reflecting structure 220, in accordance with an embodiment of the present disclosure. Further, according to an embodiment of the present disclosure, a support structure 270 for supporting the piezoelectric layer may be provided on at least one side of the lower electrode 230. According to an embodiment of the present disclosure, the support structures 260 and 270 serve to support the piezoelectric layer 240 formed on the lower electrode 230.
According to embodiments of the present disclosure, the support structures 260 and 270 may be made of silicon nitride (SiN), aluminum oxide (Al 2 O 3 ) And aluminum (Al).
Furthermore, the support structures 260 and 270 may also be used as temperature compensation components according to embodiments of the present disclosure. In this regard, the temperature coefficients of frequencies of the support structures 260 and 270, which are temperature compensation components, together with the temperature coefficients of frequencies of the lower electrode 230, the piezoelectric layer 240, and the upper electrode 250 determine the temperature coefficients of frequencies of the resonators. In particular, the temperature coefficient of frequency of the support structures 260 and 270 may be opposite to the temperature coefficient of frequency of the piezoelectric layer 240. For example, in the case where the piezoelectric layer 240 has a negative frequency temperature coefficient, the temperature compensation part 260 may have a positive frequency temperature coefficient. In the case of forming the piezoelectric layer 240 using aluminum nitride (AlN), the material forming the support structures 260 and 270 may be tellurium oxide (TeO), silicon oxide (SiO) 2 ) Or a combination thereof.
Further, according to the embodiment of the present disclosure, the supporting structures 260 and 270 may also be made of a porous material formed of the above-described materials, so that the sound reflection effect in the vertical direction may be improved.
Further, although the support structure 260 is illustrated as a single support structure disposed at the center of the acoustic reflection structure 220 in the lower electrode 230 in fig. 2B, the present disclosure is not limited thereto. According to embodiments of the present disclosure, there may be a plurality of support structures 260, which may be disposed in an array in the acoustic reflecting structure 220 in the lower electrode 230.
As shown in fig. 2B, a piezoelectric layer 240 may be disposed on the lower electrode 230 to cover the acoustic reflection structure 220. According to an embodiment of the present disclosure, the piezoelectric layer 240 may be made of a piezoelectric material, which may be selected from an inorganic piezoelectric (single crystal or polycrystalline) material or an organic piezoelectric material. Examples of piezoelectric materials may include: wurtzite structures such as aluminum nitride (AlN), zinc oxide (ZnO); perovskite structures, e.g. BaTiO 3 、Pb(Ti,Zr)O 3 、Li(Nb,Ta)O 3 、(K,Na)NbO 3 The method comprises the steps of carrying out a first treatment on the surface of the To be used forAnd organic piezoelectric materials such as polyvinylidene fluoride PVDF and the like.
Furthermore, according to embodiments of the present disclosure, the piezoelectric layer 240 may be doped with a doping element for adjusting the electromechanical coupling coefficient and the quality factor of the piezoelectric layer 240. According to an embodiment of the present 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. Further, according to an embodiment of the present disclosure, the doping element for adjusting the quality factor may be selected from at least one of B, ga and In.
According to embodiments of the present disclosure, the piezoelectric layer 240 may be doped with a rare earth element such as Sc in a doping ratio of 1% to 20%.
As shown in fig. 2B, an upper electrode 250 may be disposed on the piezoelectric layer 240. Similar to the lower electrode 230, the upper electrode 250 may include a conductive material according to embodiments of the present disclosure. For example, in accordance with 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.
According to embodiments of the present disclosure, the lower electrode 230 and the upper electrode 250 may together provide an oscillating electric field along a vertical direction when electrically stimulated.
Although the lower electrode 230 of the center resonator 201 and the lower electrode 230 of the first ring resonator 202 are shown spaced apart from each other and the upper electrode 250 of the center resonator 201 and the upper electrode 250 of the first ring resonator 202 are spaced apart from each other in fig. 2B, it should be recognized by those skilled in the art that the above-mentioned electrical connection between the center resonator 201 and the first to fourth ring resonators 202 to 205 may be achieved by the lower electrode 230 and/or the upper electrode 250. That is, the lower electrode 230 and/or the upper electrode 250 belonging to the different resonators 201 to 205 may be partially connected to achieve electrical connection between the ring resonator and the center resonator.
For the center resonator 201 and each of the first to fourth ring resonators 202 to 205, the areas where the lower electrode 230, the piezoelectric layer 240, and the upper electrode 250 overlap the acoustic reflection structure 220 constitute effective resonance areas of the resonators.
As shown in fig. 2B, a microstructure 280 for reducing propagation of acoustic waves in a horizontal direction perpendicular to a vertical direction is provided in the upper electrode 250 according to an embodiment of the present disclosure. As shown in fig. 2B, microstructures 280 may have a bridge structure and a wing structure according to embodiments of the present disclosure.
Although the microstructure 280 is shown in fig. 2B as being disposed in the upper electrode 250, the present disclosure is not limited thereto. In other embodiments of the present disclosure, microstructures 280 may also be provided in the lower electrode 230, as will be described in more detail with reference to fig. 2C. Further, although the microstructures 280 are shown in fig. 2B as having a bridge structure and a wing structure, the present disclosure is not limited thereto. In other embodiments of the present disclosure, the microstructures 280 may also have structures such as cavities, depressions, and/or protrusions, as long as the propagation of sound waves in the horizontal direction can be suppressed.
Further, although the microstructure 280 is shown in fig. 2B as being disposed in the lower surface of the upper electrode 250, the present disclosure is not limited thereto. In other embodiments of the present disclosure, microstructures 280 may also be disposed in or within the upper surface of upper electrode 250.
In accordance with embodiments of the present disclosure, microstructures 280 can provide acoustic impedance mismatch at the boundaries of the effective resonance region. This mismatch of acoustic impedances results in reflection of the sound waves at this boundary so that the sound waves are not propagated outside the effective resonance region and thus energy losses are avoided. By avoiding such energy loss, the microstructure 280 may improve the quality factor of the resonator.
Further, according to an alternative embodiment of the present disclosure, the support structure 270 for supporting the piezoelectric layer provided at least one side of the lower electrode 230 may be omitted and the piezoelectric layer 240 may be supported using only the support structure 260 formed in the acoustic reflection structure 220. Fig. 2C illustrates a partial cross-sectional view taken along line A-A' in fig. 2A, according to an alternative embodiment of the present disclosure.
As shown in fig. 2C, the support structure 270 shown in fig. 2B is omitted in the lower electrode 230 according to an alternative embodiment of the present disclosure. Further, according to an alternative embodiment of the present disclosure, similar to the upper electrode 250, a microstructure 290 for reducing propagation of acoustic waves in a horizontal direction perpendicular to the vertical direction is provided in the lower electrode 230. As shown in fig. 2C, microstructures 290 may have a bridge structure and a wing structure according to alternative embodiments of the present disclosure.
Further, although the microstructures 290 are shown in fig. 2C as having a bridge structure and a wing structure, the present disclosure is not limited thereto. In other embodiments of the present disclosure, the microstructures 290 may also have structures such as cavities, depressions, and/or protrusions, as long as the propagation of sound waves in the horizontal direction can be suppressed.
Further, although the microstructures 290 are shown in fig. 2C as being disposed in the lower surface of the lower electrode 230, the present disclosure is not limited thereto. In other embodiments of the present disclosure, microstructures 290 may also be provided in or within the upper surface of the lower electrode 230.
Fig. 3 shows a flow chart of a method 300 of manufacturing a filter according to an embodiment of the disclosure.
As shown by the solid line box in fig. 3, the method 300 of manufacturing an acoustic resonator according to an embodiment of the present disclosure includes the steps of:
s310: forming a lower electrode on a substrate;
s320: forming an acoustic reflecting structure in the lower electrode of the central resonator and/or the at least one ring resonator;
s330: forming a piezoelectric layer covering the acoustic reflection structure on the lower electrode; and
s340: an upper electrode is formed on the piezoelectric layer.
Preferably, as shown in dashed boxes in fig. 3, the manufacturing method 300 may further comprise the steps of:
s325: forming a support structure for supporting the piezoelectric layer at the center and/or at least one side of the lower electrode;
s345: forming a microstructure for reducing propagation of acoustic waves in a horizontal direction perpendicular to the vertical direction in the upper electrode and/or the lower electrode; and
s350: 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 above respective steps of the method of manufacturing a filter according to the embodiment of the present disclosure may be implemented by semiconductor processes known to those skilled in the art, such as deposition, etching, sputtering, etc., respectively, and thus specific process details thereof will not be described in more detail herein.
According to the filter and the manufacturing method thereof of the present disclosure, by arranging a plurality of resonators of the filter in a nested manner, the integration level of the filter can be improved and the volume of the filter can be reduced without increasing the process complexity, and the area ratio of the circumference of the resonators can also be increased, thereby improving the heat dissipation performance of the resonators and the overall power capacity of the filter.
Further, according to the filter and the method of manufacturing the same of the present disclosure, by providing the acoustic reflection structure in the lower electrode of the resonator constituting the filter, the substrate does not need to be etched, and the stability of the filter can be improved.
Further, according to the filter and the method of manufacturing the same of the present disclosure, by forming an acoustic impedance mismatch structure between resonators constituting the filter, the transmission of transverse waves can be reduced, which is advantageous in improving the quality factor.
Further, according to the filter and the method of manufacturing the same of the present disclosure, by providing a microstructure in the upper electrode and/or the lower electrode of each resonator of the filter to reduce lateral acoustic wave propagation, loss of resonance energy can be reduced, thereby improving the quality factor of the acoustic resonator.
Although the present disclosure has been described with reference to exemplary embodiments thereof, those skilled in the art will appreciate that various modifications and changes can be made without departing from the spirit and scope of the present disclosure as set forth in the appended claims.

Claims (19)

1. A filter, comprising:
a center resonator; and
at least one ring resonator disposed around and electrically connected to the center resonator,
wherein the central resonator and the at least one ring resonator each include a lower electrode, a piezoelectric layer, and an upper electrode sequentially arranged in a vertical direction, an
Wherein an acoustic reflecting structure is provided in the lower electrode of the central resonator and/or the at least one ring resonator.
2. A filter according to claim 1,
wherein acoustic impedance mismatch structures are provided between the center resonator and the at least one ring resonator and between the at least one ring resonator and each other.
3. A filter according to claim 2,
wherein the acoustic impedance mismatch structure is an isolation groove.
4. A filter according to claim 1,
wherein the central resonator has a circular, elliptical, polygonal or profiled shape, an
Wherein the at least one ring resonator is formed in a ring shape corresponding to the shape of the center resonator.
5. The filter of claim 1, wherein the acoustic reflecting structure is a cavity or a bragg reflector.
6. The filter of claim 1, wherein a parallel and/or series electrical connection is formed between the central resonator and the at least one ring resonator.
7. The filter of claim 6, wherein the electrical connection between the central resonator and the at least one ring resonator is achieved by the upper electrode and/or the lower electrode.
8. The filter according to claim 1, wherein the acoustic reflecting structure is provided in and/or inside an upper surface and/or a lower surface of the lower electrode.
9. The filter according to claim 1, wherein a support structure for supporting the piezoelectric layer is provided at a center and/or at least one side of the lower electrode.
10. The filter of claim 9, wherein the support structure is composed of a material selected from SiN, al 2 O 3 Al and SiO 2 At least one of the porous materials.
11. The filter according to claim 1, wherein a microstructure for reducing propagation of acoustic waves in a horizontal direction perpendicular to the vertical direction is provided in the upper electrode and/or the lower electrode.
12. The filter of claim 11, wherein the microstructures comprise bridge structures and/or wing structures.
13. The filter of 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.
14. A method of manufacturing a filter, the method comprising,
the filter includes:
a center resonator; and
at least one ring resonator disposed around and electrically connected to the center resonator,
wherein the central resonator and the at least one ring resonator each comprise a lower electrode, a piezoelectric layer and an upper electrode which are sequentially arranged along the vertical direction,
the manufacturing method comprises the following steps:
forming the lower electrode on a substrate;
forming an acoustic reflecting structure in a lower electrode of the central resonator and/or the at least one ring resonator;
forming the piezoelectric layer covering the acoustic reflection structure on the lower electrode; and
the upper electrode is formed on the piezoelectric layer.
15. The manufacturing method according to claim 14, further comprising: 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.
16. The manufacturing method according to claim 15,
wherein the acoustic impedance mismatch structure is an isolation groove.
17. The manufacturing method according to claim 14, 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.
18. The manufacturing method according to claim 14, further comprising: a microstructure for reducing propagation of acoustic waves in a horizontal direction perpendicular to the vertical direction is formed in the upper electrode and/or the lower electrode.
19. The method of manufacturing of claim 18, wherein the microstructures comprise bridge structures and/or wing structures.
CN202111625208.9A 2021-12-28 2021-12-28 Filter and method for manufacturing the same Pending CN116366024A (en)

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CN202111625208.9A CN116366024A (en) 2021-12-28 2021-12-28 Filter and method for manufacturing the same

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202111625208.9A CN116366024A (en) 2021-12-28 2021-12-28 Filter and method for manufacturing the same

Publications (1)

Publication Number Publication Date
CN116366024A true CN116366024A (en) 2023-06-30

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Family Applications (1)

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Country Status (1)

Country Link
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