Acoustic wave resonator, method for preparing acoustic wave resonator, and filter

Abstract

The present invention relates to the field of microelectronic devices and discloses an acoustic wave resonator, a method for preparing an acoustic wave resonator, and a filter. The acoustic wave resonator includes a supporting substrate, an energy reflection structure disposed on the supporting substrate, a bottom electrode disposed on the energy reflection structure, a piezoelectric film disposed on the bottom electrode, the piezoelectric film having a piezoelectric effective region and a piezoelectric failure region, an interdigitated top electrode array disposed on the piezoelectric effective region, the piezoelectric failure region being an area between the interdigitated top electrode arrays and not covered by the interdigitated top electrode arrays, the width of the piezoelectric failure region being less than or equal to the width of the area not covered by the interdigitated top electrode arrays, and the target mode of the acoustic wave resonator being excited by a longitudinal electric field. The embodiment of the present invention is based on a heterogeneous integrated structure and, while ensuring the integrity of the piezoelectric film, suppresses spurious modes excited by the transverse electric field by disposing a piezoelectric failure region of a certain width in the piezoelectric film. The method is simple in process and is conducive to the preparation of high-performance acoustic wave resonators.

Description

Technical Field

[0001] The present invention relates to the field of microelectronic devices, and in particular to an acoustic wave resonator, a method for preparing the acoustic wave resonator, and a filter. Background Art

[0002] The modern communications industry has increasingly stringent requirements for signal quality, while competition for communications spectrum resources is also intensifying. Increasingly crowded frequency bands require filters to have sufficient out-of-band suppression outside the passband to avoid conflicts with other frequency bands. However, when spurious modes other than the target mode exist in the resonators that make up the filter, additional passbands will appear outside the target mode band. In piezoelectric crystals of specific cut types, due to their complex piezoelectric coefficients and stiffness coefficient components, when one acoustic wave mode is the target mode, other modes are often accompanied by spurious modes. Spurious mode suppression may be achieved by selecting the appropriate acoustic wave resonator geometry and materials for each layer based on the dispersion characteristics of the spurious mode. However, there are also cases where achieving spurious suppression through geometric structure optimization is difficult or requires sacrificing other device performance.

[0003] When the target mode is an acoustic mode excited by a longitudinal electric field, the longitudinal electric field is primarily concentrated below the interdigitated top electrode, while the transverse electric field exists in the region between the interdigitated top electrodes. The region between the interdigitated electrodes has almost no longitudinal electric field and does not contribute to the target mode, but the transverse electric field does generate spurious modes. Therefore, suppressing spurious modes excited by the transverse electric field using a simple process is key to achieving high-performance acoustic resonators.

[0004] In the prior art, the method used to suppress the stray modes excited by the transverse electric field is to etch away the piezoelectric film between the interdigital top electrodes. After adopting this method, the piezoelectric film below the interdigital top electrodes is etched into a ridge shape, while the piezoelectric film between the interdigital top electrodes is partially etched away. In this way, almost only the longitudinal electric field exists in the remaining piezoelectric film, and the stray modes excited by the transverse electric field can be suppressed. However, the disadvantage of this method is that it leaves grooves formed by etching between the interdigital top electrodes, which not only increases the process difficulty, but also makes the structure more fragile. The undesirable etching surface and etching angle will also greatly increase the energy dissipation of the acoustic wave. Summary of the Invention

[0005] The embodiments of the present application provide an acoustic wave resonator, a method for preparing an acoustic wave resonator, and a filter. The embodiments of the present invention are based on a heterogeneous integrated structure. While ensuring the integrity of the piezoelectric film, a piezoelectric failure area of ​​a certain width is set in the piezoelectric film to suppress the stray modes excited by the transverse electric field. This method has a simple process and is conducive to the preparation of high-performance acoustic wave resonators.

[0006] In one aspect, an embodiment of the present invention provides an acoustic wave resonator, comprising:

[0007] a supporting substrate;

[0008] an energy reflecting structure disposed on a supporting substrate;

[0009] a bottom electrode disposed on the energy reflecting structure;

[0010] A piezoelectric film is provided on the bottom electrode; the piezoelectric film includes a piezoelectric effective region and a piezoelectric failure region;

[0011] an interdigitated top electrode array disposed on the piezoelectric active area;

[0012] The piezoelectric failure region is located between the interdigitated top electrode arrays and is not covered by the interdigitated top electrode arrays; the width of the piezoelectric failure region is less than or equal to the width of the region not covered by the interdigitated top electrode arrays;

[0013] The target mode of the acoustic resonator is excited by the longitudinal electric field.

[0014] Optionally, the method for forming the piezoelectric failure region includes at least one of post-annealing or ion implantation.

[0015] Optionally, the support substrate includes one of lithium niobate, lithium tantalate, silicon, quartz, spinel, germanium, silicon carbide, diamond, diamond-like carbon, sapphire, aluminum nitride, and silicon nitride.

[0016] Optionally, the energy reflection structure includes one of a low acoustic velocity dielectric layer, a Bragg reflection layer, and a cavity.

[0017] Optionally, the bottom electrode includes one of a surface electrode or an interdigitated electrode;

[0018] If the bottom electrode is an interdigitated electrode, the position of the bottom electrode is set in one-to-one correspondence with the position of the interdigitated top electrode array.

[0019] Optionally, the material of the piezoelectric film includes at least one of lithium niobate, lithium tantalate, potassium niobate, aluminum nitride, scandium-doped aluminum nitride, zinc oxide, lead zirconate titanate piezoelectric ceramics, or lead magnesium niobate-lead titanate.

[0020] Optionally, the modes of the acoustic wave resonator include horizontal shear mode, Lamb wave mode, Rayleigh mode, horizontal shear high-order mode, Lamb wave high-order mode and Rayleigh high-order mode.

[0021] Optionally, when the interdigitated top electrode array of the acoustic wave resonator is an aluminum electrode, the piezoelectric film is X-cut lithium niobate, the piezoelectric film includes a piezoelectric failure area, the bottom electrode is a platinum electrode, the energy reflection structure is a silicon oxide layer, the supporting substrate is 6H-silicon carbide, and the mode of the acoustic wave resonator is a first-order horizontal shear mode, the width of the piezoelectric failure area is equal to the width of the area not covered by the interdigitated top electrode array.

[0022] Optionally, when the interdigitated top electrode array of the acoustic wave resonator is an aluminum electrode, the piezoelectric film is Y163-cut lithium niobate, the piezoelectric film includes a piezoelectric failure area, the bottom electrode is a platinum electrode, the energy reflection structure is a Bragg reflection layer, the supporting substrate is sapphire, and the mode of the acoustic wave resonator is a first-order horizontal shear mode, the width of the piezoelectric failure area is equal to the width of the area not covered by the interdigitated top electrode array.

[0023] Optionally, when the interdigitated top electrode array of the acoustic wave resonator is an aluminum electrode, the piezoelectric film is Y-cut lithium niobate, the piezoelectric film includes a piezoelectric failure area, the bottom electrode is an aluminum electrode, and the mode of the acoustic wave resonator is a first-order horizontal shear mode, the width of the piezoelectric failure area is equal to the width of the area not covered by the interdigitated top electrode array.

[0024] In another aspect, an embodiment of the present invention provides a method for preparing an acoustic wave resonator, the method comprising:

[0025] Providing an intermediate structure; the intermediate structure comprises, from bottom to top, a supporting substrate, an energy reflecting structure, a bottom electrode and a piezoelectric film;

[0026] A piezoelectric failure region is formed in the piezoelectric film, and an interdigitated top electrode array is arranged on the piezoelectric effective region; the width of the piezoelectric failure region is less than or equal to the width of the region not covered by the interdigitated top electrode array.

[0027] Optionally, forming a piezoelectric failure region in the piezoelectric film and disposing an interdigitated top electrode array on the piezoelectric effective region includes:

[0028] forming a piezoelectric failure region in the piezoelectric film based on a post-annealing method or an ion implantation method;

[0029] An interdigitated top electrode array is disposed on the piezoelectric active area.

[0030] On the other hand, an embodiment of the present invention provides a filter, comprising a plurality of resonators, wherein the resonator is any of the above-mentioned acoustic wave resonators.

[0031] The acoustic wave resonator, the method for preparing the acoustic wave resonator, and the filter provided in the embodiments of the present application have the following technical effects:

[0032] The acoustic wave resonator includes a supporting substrate, an energy reflection structure disposed on the supporting substrate, a bottom electrode disposed on the energy reflection structure, a piezoelectric film disposed on the bottom electrode, the piezoelectric film including a piezoelectric effective region and a piezoelectric failure region, an interdigitated top electrode array disposed on the piezoelectric effective region, the piezoelectric failure region being located between the interdigitated top electrode arrays and not covered by the interdigitated top electrode arrays, the width of the piezoelectric failure region being less than or equal to the width of the region not covered by the interdigitated top electrode arrays, and the target mode of the acoustic wave resonator being excited by a longitudinal electric field. The embodiment of the present invention suppresses spurious modes excited by a transverse electric field by providing a piezoelectric failure region of a certain width in the piezoelectric film while ensuring the integrity of the piezoelectric film. This method is simple in process and is conducive to the preparation of a high-performance acoustic wave resonator. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions and advantages of the embodiments of the present application or the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0034] Figure 1 is a cross-sectional schematic diagram of an acoustic wave resonator provided in an embodiment of the present application;

[0035] Figure 2 1 is a schematic cross-sectional view of an acoustic wave resonator based on an X-cut lithium niobate / platinum / silicon oxide / 6H-silicon carbide substrate provided in an embodiment of the present application;

[0036] Figure 3 This is a schematic cross-sectional view of an acoustic wave resonator having a piezoelectric failure region based on an X-cut lithium niobate / platinum / silicon oxide / 6H-silicon carbide substrate provided in an embodiment of the present application;

[0037] Figure 4 This is a simulated admittance curve of a first-order horizontal shear mode resonator with different treatments of an acoustic wave resonator provided in an embodiment of the present application;

[0038] Figure 5 This is a schematic cross-sectional view of an acoustic wave resonator based on a Y163-cut lithium niobate / platinum / Bragg reflector / sapphire substrate provided in an embodiment of the present application;

[0039] Figure 6 This is a schematic cross-sectional view of an acoustic wave resonator having a piezoelectric failure region based on a Y163-cut lithium niobate / platinum / Bragg reflector / sapphire substrate provided in an embodiment of the present application;

[0040] Figure 7The simulated admittance curves of a first-order horizontal shear mode resonator with a Bragg reflection layer provided by an acoustic wave resonator with different treatments are provided in an embodiment of the present application;

[0041] Figure 8 This is a cross-sectional schematic diagram of a suspended Y-cut lithium niobate film / aluminum electrode acoustic wave resonator provided in an embodiment of the present application;

[0042] Figure 9 This is a schematic cross-sectional view of an acoustic wave resonator having a piezoelectric failure region in a suspended Y-cut lithium niobate film / aluminum electrode provided in an embodiment of the present application;

[0043] Figure 10 1 is a schematic diagram showing the variation of the simulated admittance curve of an unprocessed first-order horizontal shear mode resonator with R provided in an embodiment of the present application;

[0044] Figure 11 1 is a schematic diagram showing a change in a simulated admittance curve of a first-order horizontal shear mode resonator with local piezoelectric failure as a function of the ratio R of the uncovered area of ​​the top electrode provided in an embodiment of the present application;

[0045] Figure 12 This is a comparison diagram of the electromechanical coupling coefficient of a resonator without treatment and with local piezoelectric failure treatment as a function of the ratio R of the uncovered area of ​​the top electrode provided in an embodiment of the present application;

[0046] Figure 13 This is a schematic diagram of a method for preparing an acoustic wave resonator provided in an embodiment of the present application. DETAILED DESCRIPTION

[0047] The following will be combined with the accompanying drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0048] It should be noted that the terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or server that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products, or devices.

[0049] The following describes a specific embodiment of an acoustic wave resonator of the present application. Figure 1 This is a cross-sectional schematic diagram of an acoustic wave resonator provided in an embodiment of the present application. This specification provides the components shown in the embodiments or drawings, but based on routine or non-creative work, more or fewer modules or components may be included. The components listed in the embodiments are only one of many components and do not represent the only components. In actual implementation, the components shown in the embodiments or drawings can be used.

[0050] Specific as Figure 1 As shown, the acoustic wave resonator may include: a supporting substrate 101, an energy reflecting structure 102 arranged on the supporting substrate, a bottom electrode 103 arranged on the energy reflecting structure, a piezoelectric film arranged on the bottom electrode, the piezoelectric film may include a piezoelectric effective area 104 and a piezoelectric failure area 105, and an interdigitated top electrode array 106 arranged on the piezoelectric effective area.

[0051] Optionally, the material of the support substrate may include one of lithium niobate LiNbO 3 , lithium tantalate LiTaO 3 , silicon, quartz, spinel, germanium, silicon carbide, diamond, diamond-like carbon, sapphire, aluminum nitride, and silicon nitride.

[0052] Optionally, the energy reflection structure may include one of a low acoustic velocity dielectric layer, a Bragg reflection layer, and a cavity. Providing the energy reflection structure may effectively prevent the generated sound waves from leaking into the supporting substrate.

[0053] Optionally, the material of the piezoelectric film may include at least one of lithium niobate LiNbO3, lithium tantalate LiTaO3, potassium niobate, aluminum nitride, scandium-doped aluminum nitride, zinc oxide, lead zirconate titanate piezoelectric ceramics, or lead magnesium niobate-lead titanate.

[0054] Optionally, the bottom electrode provided on the energy reflection structure may include one of a surface electrode or an interdigitated electrode. If the bottom electrode provided is a surface electrode, the size of the surface electrode provided may be consistent with the size of the energy reflection structure. If the bottom electrode provided is an interdigitated electrode, the position and size of the bottom electrode may be set in one-to-one correspondence with the position and size of the interdigitated top electrode array provided on the piezoelectric effective area. The interdigitated top electrode array may provide an electrical signal, and the electrical signal generates an electric field. Since a bottom electrode corresponding to the interdigitated top electrode array is also provided, the target mode of the acoustic wave resonator in the present application is mainly excited by the longitudinal electric field, that is, the electrical signal provided by the interdigitated top electrode array generates a longitudinal electric field, and the longitudinal electric field excites the generation of acoustic waves.

[0055] In the embodiment of this application, Figure 1Continuing to elaborate, the piezoelectric failure region can be located in the region of the piezoelectric film between two adjacent interdigitated top electrodes and not covered by the interdigitated top electrode array. Furthermore, the width of the piezoelectric failure region can be less than or equal to the width of the region not covered by the interdigitated top electrode array. Optionally, when the acoustic wave resonator is fully excited by the longitudinal electric field, the electromechanical coupling coefficient of the acoustic wave resonator can be adjusted by adjusting the width ratio of the piezoelectric failure region to accommodate bandwidth requirements in different applications.

[0056] In an embodiment of the present application, the method for forming a piezoelectric failure area may include at least one of post-annealing or ion implantation. Post-annealing can be used to release elements in a part of the piezoelectric film. For example, when the material of the piezoelectric film is lithium niobate (LiNbO3), the lithium element or oxygen element therein can be released by post-annealing, resulting in the destruction of the crystal structure of the piezoelectric material, and the piezoelectric coefficient decreases or even almost to zero, thereby forming a piezoelectric failure area in a part of the piezoelectric film while maintaining the integrity of the piezoelectric film. At the same time, when the annealing method is adopted, it is necessary to use an inactive material as a mask to protect the piezoelectric effective area, or to set an easily oxidizable material where the piezoelectric failure area is intended to be formed. Among them, the inactive material may include gold, platinum, palladium, etc., and the easily oxidizable material may include cadmium, magnesium, lithium, etc.

[0057] Optionally, the principle of forming a piezoelectric failure area in a partial area of ​​the piezoelectric film by ion implantation is to destroy the lattice structure of the single crystal piezoelectric material, so that the piezoelectric coefficient decreases or even almost reaches zero, thereby forming a piezoelectric failure area in a partial area of ​​the piezoelectric film, while maintaining the integrity of the piezoelectric film.

[0058] Optionally, the modes of the acoustic wave resonator may include a horizontal shear mode, a Lamb wave mode, a Rayleigh mode, a horizontal shear high-order mode, a Lamb wave high-order mode, and a Rayleigh high-order mode. The high-order modes of the horizontal shear mode are the 1st-order horizontal shear mode, the 2nd-order horizontal shear mode, and the 3rd-order horizontal shear mode. The basic horizontal shear mode is the 0th order. Similarly, the modes of the acoustic wave resonator may also include the Lamb wave mode and the Lamb wave high-order mode, the Rayleigh mode, and the Rayleigh high-order mode.

[0059] In an optional embodiment, Figure 2 : is a cross-sectional schematic diagram of an acoustic wave resonator based on an X-cut lithium niobate / platinum / silicon oxide / 6H-silicon carbide substrate provided in an embodiment of the present application, such as Figure 2 As shown in the figure, the interdigitated top electrode array of the acoustic wave resonator is an aluminum electrode, the material of the piezoelectric film is X-cut lithium niobate, the piezoelectric film does not contain a piezoelectric failure area, the bottom electrode is a platinum electrode, the energy reflection structure is a silicon oxide layer, and the material of the supporting substrate is 6H-silicon carbide.

[0060] Figure 3Schematic diagram of a cross section of an acoustic wave resonator based on an X-cut lithium niobate / platinum / silicon oxide / 6H-silicon carbide substrate with a piezoelectric failure region provided in an embodiment of the present application. Figure 3 As shown, in Figure 2 Based on the acoustic wave resonator shown in FIG, a portion of the X-cut lithium niobate piezoelectric film is treated by post-annealing or ion implantation to obtain the following Figure 3 The acoustic wave resonator shown has a piezoelectric failure area based on an X-cut lithium niobate / platinum / silicon oxide / 6H-silicon carbide substrate, wherein the interdigitated top electrode array is an aluminum electrode with a thickness of 80 nm, the piezoelectric film is X-cut lithium niobate, the thickness of the piezoelectric film is 250 nm, the piezoelectric film includes a piezoelectric failure area, the bottom electrode is a platinum electrode with a thickness of 35 nm, the energy reflection structure is a silicon oxide layer with a thickness of 200 nm, the supporting substrate is 6H-silicon carbide, the wavelength is 1.25 μm, the duty cycle of the interdigitated top electrode array is 0.6, and when the mode of the acoustic wave resonator is a first-order horizontal shear mode, the width of the piezoelectric failure area is equal to the width of the area not covered by the interdigitated top electrode array.

[0061] Among them, the target mode of the acoustic wave resonator (i.e., the first-order horizontal shear mode) is mainly excited by the longitudinal electric field, while the spurious modes (i.e., other modes except the first-order horizontal shear mode, such as Rayleigh mode, zero-order horizontal shear mode (Fundamental shear horizontal mode, SH0), zero-order symmetric Lamb wave mode (Fundamentalsymmetric Lamb wave mode, S0) and fast shear wave, etc.) are mostly excited by the transverse electric field.

[0062] In the embodiment of this application, Figure 4 The first-order horizontal shear mode resonator simulated admittance curve of an acoustic wave resonator with different treatments provided in the embodiment of the present application is as follows: Figure 4 As shown, in the settings Figure 2 In the case of an untreated acoustic wave resonator (i.e., the piezoelectric film does not have a piezoelectric failure region), the Euler angles of lithium niobate are (35, 90, -90), which can be obtained from Figure 4It can be seen from the figure that when no optimization treatment is performed, the first-order shear horizontal mode (SH1) resonator has multiple spurious modes, such as Rayleigh mode, zero-order horizontal shear mode, zero-order symmetric Lamb wave mode and fast shear wave. After optimizing the in-plane orientation treatment, it can be clearly seen that the fast shear wave is suppressed. At this time, the Euler angle of lithium niobate is (19, 90, -90), but it is impossible to suppress other spurious waves (such as Rayleigh mode, zero-order horizontal shear mode, zero-order symmetric Lamb wave mode) while suppressing the fast shear wave. After the local piezoelectric failure treatment is adopted (that is, setting Figure 3 The acoustic wave resonator shown in the figure has a local piezoelectric failure area), the Euler angle of lithium niobate is still (35, 90, -90), and the clutter caused by the transverse electric field (such as Rayleigh mode, zero-order horizontal shear mode, zero-order symmetric Lamb wave mode and fast shear wave) is basically completely gone.

[0063] A piezoelectric failure area is formed on the piezoelectric film through post-annealing, ion implantation and other methods. This method is different from etching to remove the piezoelectric film between the interdigitated top electrode array. The surface morphology of the piezoelectric film is not damaged, and the process is relatively simple while suppressing noise. The effect of suppressing noise is relatively good. Therefore, this method is suitable for realizing high-performance noise-free acoustic wave resonators.

[0064] In an optional embodiment, Figure 5 : is a schematic cross-sectional view of an acoustic wave resonator based on a Y163-cut lithium niobate / platinum / Bragg reflection layer / sapphire substrate provided in an embodiment of the present application, as shown in FIG. Figure 5 As shown in the figure, the interdigitated top electrode array of the acoustic wave resonator is an aluminum electrode, the material of the piezoelectric film is Y163-cut lithium niobate, the piezoelectric film does not contain a piezoelectric failure area, the bottom electrode is a platinum electrode, the energy reflection structure is a Bragg reflection layer (the Bragg reflection layer is composed of 3 periods of silicon oxide / platinum), and the material of the supporting substrate is sapphire.

[0065] Figure 6 Schematic diagram of a cross section of an acoustic wave resonator with a piezoelectric failure region based on a Y163-cut lithium niobate / platinum / Bragg reflector / sapphire substrate provided in an embodiment of the present application. Figure 6 As shown, in Figure 5 Based on the acoustic wave resonator shown in FIG, a portion of the Y163-cut lithium niobate piezoelectric film is treated by post-annealing or ion implantation to obtain the following Figure 6The acoustic wave resonator shown in the figure, based on a Y163-cut lithium niobate / platinum / Bragg reflector / sapphire substrate with a piezoelectric failure region, has an interdigitated top electrode array of aluminum electrodes with a thickness of 80 nm, a piezoelectric film of Y163-cut lithium niobate with a thickness of 180 nm, and includes a piezoelectric failure region. The bottom electrode is a platinum electrode with a thickness of 25 nm. The energy reflection structure is a Bragg reflector layer composed of three periods of silicon oxide / platinum with thicknesses of 160 nm and 75 nm. The supporting substrate is sapphire, the wavelength is 2 μm, the duty cycle of the interdigitated top electrode array is 0.7, and when the acoustic wave resonator mode is the first-order horizontal shear mode, the width of the piezoelectric failure region is equal to the width of the area not covered by the interdigitated top electrode array. The target mode of the acoustic wave resonator (i.e., the first-order horizontal shear mode) is primarily excited by the longitudinal electric field, while the spurious modes are mostly excited by the horizontal electric field.

[0066] In the embodiment of this application, Figure 7 The simulated admittance curves of the first-order horizontal shear mode resonator with a Bragg reflection layer provided by an acoustic wave resonator with different treatments are shown in FIG. Figure 7 As shown, in the settings Figure 5 In the case of an untreated acoustic wave resonator (i.e., the piezoelectric film does not have a piezoelectric failure region), the first-order horizontal shear mode resonator has multiple spurious modes when no optimization is performed. The spurious modes are excited by the horizontal electric field. When a localized piezoelectric failure treatment is applied (i.e., the piezoelectric film is set as Figure 6 In the acoustic wave resonator shown, which has a localized piezoelectric failure region, the spurious modes excited by the horizontal electric field are essentially suppressed.

[0067] It can also be concluded that by forming a piezoelectric failure area on the piezoelectric film through methods such as post-annealing and ion implantation, this method can effectively suppress noise without destroying the surface morphology of the piezoelectric film.

[0068] In an optional embodiment, Figure 8 : is a cross-sectional schematic diagram of a suspended Y-cut lithium niobate film / aluminum electrode acoustic wave resonator provided in an embodiment of the present application, such as Figure 8 As shown in the figure, the interdigitated top electrode array of the acoustic wave resonator is an aluminum electrode, the material of the piezoelectric film is a Y-cut lithium niobate film, the piezoelectric film does not contain a piezoelectric failure area, and the bottom electrode is an aluminum electrode.

[0069] Figure 9 : is a cross-sectional schematic diagram of an acoustic wave resonator with a suspended Y-cut lithium niobate film / aluminum electrode having a piezoelectric failure region provided by an embodiment of the present application, such as Figure 9 As shown, in Figure 8Based on the acoustic wave resonator shown in FIG, a part of the Y-cut lithium niobate film is treated by post-annealing or ion implantation to obtain the following Figure 9 The acoustic wave resonator shown has a piezoelectric failure area in a suspended Y-cut lithium niobate film / aluminum electrode. The interdigitated top electrode array is an aluminum electrode with a thickness of 60 nm. The piezoelectric film is a Y-cut lithium niobate with a thickness of 400 nm. The piezoelectric film includes a piezoelectric failure area. The bottom electrode is an aluminum electrode with a thickness of 20 nm and a wavelength of 3.2 μm. When the mode of the acoustic wave resonator is a first-order horizontal shear mode, the width of the piezoelectric failure area is equal to the width of the area not covered by the interdigitated top electrode array.

[0070] In the embodiment of the present application, it is assumed that the ratio of the width of the uncovered area of ​​the interdigitated top electrode array to the total width in each cycle is R. Figure 8 Based on the acoustic wave resonator shown, Figure 10 : is a schematic diagram of the change of the simulated admittance curve of an unprocessed first-order horizontal shear mode resonator with R, as provided in an embodiment of the present application. Figure 10 As shown in the figure, it can be seen that as R increases, the target mode (i.e., the first-order horizontal shear mode) has no obvious difference except that the frequency becomes higher. That is to say, the larger R is (the larger the proportion of the width of the uncovered area), that is, the smaller the duty cycle is, the target mode (i.e., the first-order horizontal shear mode) has no obvious difference except that the frequency becomes higher.

[0071] In the embodiment of the present application, it is assumed that the ratio of the width of the uncovered area of ​​the interdigitated top electrode array to the total width in each cycle is R. Figure 9 Based on the acoustic wave resonator shown, Figure 11 : is a schematic diagram of a simulated admittance curve of a first-order horizontal shear mode resonator with local piezoelectric failure provided by an embodiment of the present application, as shown in FIG. Figure 11 As shown, it can be seen that with the increase of R, the resonant frequency of the resonator becomes larger and the antiresonant frequency becomes smaller, which means that the electromechanical coupling coefficient also decreases with the increase of R.

[0072] In the embodiment of this application, Figure 12 : is a comparison diagram of the electromechanical coupling coefficient of the resonator without treatment and with local piezoelectric failure treatment according to the ratio R of the top electrode uncovered area provided in the embodiment of the present application, such as Figure 12 As shown in the figure, it can be seen that R has little effect on the electromechanical coupling coefficient of the untreated first-order horizontal shear mode resonator, but it drastically changes the electromechanical coupling coefficient of the first-order horizontal shear mode resonator after local piezoelectric failure treatment. This means that the electromechanical coupling coefficient of the acoustic wave resonator after local piezoelectric failure treatment can be adjusted by changing the width of the piezoelectric failure region to meet the bandwidth requirements of different application scenarios.

[0073] Therefore, based on the above analysis, for the target mode of longitudinal electric field excitation in this application, the electromechanical coupling coefficient of the acoustic wave resonator can be adjusted by adjusting the width ratio of the piezoelectric failure area on the set piezoelectric film to adapt to the bandwidth requirements of different occasions.

[0074] On the other hand, an embodiment of the present invention provides a method for preparing an acoustic wave resonator. Figure 13 Schematic diagram of a method for preparing an acoustic wave resonator provided in an embodiment of the present application. Figure 13 As shown, the method may include:

[0075] S1301: providing an intermediate structure, wherein the intermediate structure comprises, from bottom to top, a supporting substrate, an energy reflecting structure, a bottom electrode, and a piezoelectric film.

[0076] In an embodiment of the present application, the intermediate structure of the acoustic wave resonator comprises, from bottom to top, a supporting substrate, an energy reflecting structure, a bottom electrode, and a piezoelectric film. Optionally, the material of the supporting substrate may include one of lithium niobate LiNbO3, lithium tantalate LiTaO3, silicon, quartz, spinel, germanium, silicon carbide, diamond, diamond-like carbon, sapphire, aluminum nitride, and silicon nitride; the energy reflecting structure may include one of a low acoustic velocity dielectric layer, a Bragg reflection layer, and a cavity; and the material of the piezoelectric film may include at least one of lithium niobate LiNbO3, lithium tantalate LiTaO3, potassium niobate, aluminum nitride, scandium-doped aluminum nitride, zinc oxide, lead zirconate titanate piezoelectric ceramic, or lead magnesium niobate titanate. The bottom electrode provided on the energy reflecting structure may include one of a surface electrode or an interdigitated electrode. If the bottom electrode provided is a surface electrode, the size of the surface electrode provided may be consistent with the size of the energy reflecting structure. If the bottom electrode provided is an interdigitated electrode, the position and size of the bottom electrode may be set in one-to-one correspondence with the position and size of the interdigitated top electrode array provided on the piezoelectric effective area.

[0077] S1303: forming a piezoelectric failure region in the piezoelectric film, and disposing an interdigitated top electrode array on the piezoelectric effective region, wherein the width of the piezoelectric failure region is less than or equal to the width of the region not covered by the interdigitated top electrode array.

[0078] In an embodiment of the present application, a piezoelectric failure area is formed in the piezoelectric film based on a post-annealing method or an ion implantation method, and an interdigitated top electrode array is set on the piezoelectric effective area. The width of the set piezoelectric failure area needs to be less than or equal to the width of the area not covered by the interdigitated top electrode array.

[0079] The acoustic wave resonator in the present application has a transduction region composed of an array of interdigitated top electrodes, a piezoelectric film and a bottom electrode, and the piezoelectric properties of the local piezoelectric film between the interdigitated top electrode arrays can be invalidated by a post-annealing method or an ion implantation method. Due to the complex piezoelectric coefficient and stiffness coefficient components of common acoustic wave resonators, the transverse and longitudinal electric fields generated by the interdigitated top electrodes and the bottom electrodes will simultaneously excite multiple modes other than the target mode. When the target mode is excited by the longitudinal electric field, the transverse electric field concentrated between the interdigitated top electrodes becomes an important source of parasitic modes. By invalidating the piezoelectric properties of the piezoelectric film in the transverse electric field concentration area, the transverse electric field cannot produce a piezoelectric effect in this area, and thus the stray modes caused by the transverse electric field can be suppressed. For the target mode excited by the longitudinal electric field, the electromechanical coupling coefficient of the acoustic wave resonator can be adjusted by adjusting the width ratio of the piezoelectric failure area to meet the bandwidth requirements of different occasions.

[0080] On the other hand, an embodiment of the present invention provides a filter, which includes a plurality of resonators, and the resonators are any of the above-mentioned acoustic wave resonators.

[0081] The acoustic wave resonator provided by the embodiment of the present application includes a supporting substrate, an energy reflection structure arranged on the supporting substrate, a bottom electrode arranged on the energy reflection structure, a piezoelectric film arranged on the bottom electrode, the piezoelectric film including a piezoelectric effective region and a piezoelectric failure region, an interdigitated top electrode array arranged on the piezoelectric effective region, the piezoelectric failure region being located between the interdigitated top electrode arrays and not covered by the interdigitated top electrode arrays, the width of the piezoelectric failure region being less than or equal to the width of the region not covered by the interdigitated top electrode arrays, and the target mode of the acoustic wave resonator being excited by a longitudinal electric field. Under the premise of ensuring the integrity of the piezoelectric film, the embodiment of the present invention suppresses the stray mode excited by the transverse electric field by setting a piezoelectric failure region of a certain width in the piezoelectric film. This method does not require an additional etching process, so the process is relatively simple, has little effect on the quality factor of the device, has the characteristics of simple structure, flexible design, low cost, and is conducive to large-scale production of high-performance acoustic wave resonators.

[0082] It should be noted that the order of the embodiments of the present application described above is for descriptive purposes only and does not represent the superiority or inferiority of the embodiments. The above description is of specific embodiments of this specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps described in the claims can be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0083] The various embodiments in this specification are described in a progressive manner. Similar parts between the various embodiments can be referred to in conjunction with each other. Each embodiment focuses on the differences between the other embodiments. In particular, the device embodiments are generally similar to the method embodiments, so the description is relatively simple. For relevant parts, refer to the description of the method embodiments.

[0084] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. An acoustic wave resonator, characterized in that include: a supporting substrate; an energy reflecting structure disposed on the supporting substrate; a bottom electrode disposed on the energy reflecting structure; a piezoelectric film disposed on the bottom electrode; The piezoelectric film includes a piezoelectric effective region and a piezoelectric failure region; an interdigitated top electrode array disposed on the piezoelectric active area; The piezoelectric failure region is located between the interdigitated top electrode arrays and is not covered by the interdigitated top electrode arrays; the width of the piezoelectric failure region is less than or equal to the width of the region not covered by the interdigitated top electrode arrays; The piezoelectric failure region is formed in a partial region of the piezoelectric film; The method for forming the piezoelectric failure region includes post-annealing; The target mode of the acoustic wave resonator is excited by a longitudinal electric field; When the acoustic wave resonator is completely excited by the longitudinal electric field, the electromechanical coupling coefficient of the acoustic wave resonator is adjusted by adjusting the width ratio of the piezoelectric failure region.

2. The acoustic wave resonator according to claim 1, characterized in that: The method for forming the piezoelectric failure region further includes ion implantation.

3. The acoustic wave resonator according to claim 1, characterized in that: The support substrate includes one of lithium niobate, lithium tantalate, silicon, quartz, spinel, germanium, silicon carbide, diamond, diamond-like carbon, sapphire, aluminum nitride, and silicon nitride.

4. The acoustic wave resonator according to claim 1, characterized in that: The energy reflection structure includes one of a low acoustic velocity dielectric layer, a Bragg reflection layer, and a cavity.

5. The acoustic wave resonator according to claim 1, characterized in that: The bottom electrode includes one of a surface electrode or an interdigitated electrode; If the bottom electrode is an interdigitated electrode, the position of the bottom electrode is arranged in a one-to-one correspondence with the position of the interdigitated top electrode array.

6. The acoustic wave resonator according to claim 1, characterized in that: The material of the piezoelectric film includes at least one of lithium niobate, lithium tantalate, potassium niobate, aluminum nitride, scandium-doped aluminum nitride, zinc oxide, lead zirconate titanate piezoelectric ceramics or lead magnesium niobate lead titanate.

7. The acoustic wave resonator according to claim 1, characterized in that: The modes of the acoustic wave resonator include a horizontal shear mode, a Lamb wave mode, a Rayleigh mode, a horizontal shear high-order mode, a Lamb wave high-order mode, and a Rayleigh high-order mode.

8. The acoustic wave resonator according to claim 1, characterized in that: When the interdigitated top electrode array of the acoustic wave resonator is an aluminum electrode, the piezoelectric film is X-cut lithium niobate, the piezoelectric film includes the piezoelectric failure area, the bottom electrode is a platinum electrode, the energy reflection structure is a silicon oxide layer, the supporting substrate is 6H-silicon carbide, and the mode of the acoustic wave resonator is a first-order horizontal shear mode, the width of the piezoelectric failure area is equal to the width of the area not covered by the interdigitated top electrode array.

9. The acoustic wave resonator according to claim 1, characterized in that: When the interdigitated top electrode array of the acoustic wave resonator is an aluminum electrode, the piezoelectric film is Y163-cut lithium niobate, the piezoelectric film includes the piezoelectric failure area, the bottom electrode is a platinum electrode, the energy reflection structure is a Bragg reflection layer, the supporting substrate is sapphire, and the mode of the acoustic wave resonator is a first-order horizontal shear mode, the width of the piezoelectric failure area is equal to the width of the area not covered by the interdigitated top electrode array.

10. The acoustic wave resonator according to claim 1, characterized in that: When the interdigitated top electrode array of the acoustic wave resonator is an aluminum electrode, the piezoelectric film is Y-cut lithium niobate, the piezoelectric film includes the piezoelectric failure area, the bottom electrode is an aluminum electrode, and the mode of the acoustic wave resonator is a first-order horizontal shear mode, the width of the piezoelectric failure area is equal to the width of the area not covered by the interdigitated top electrode array.

11. A method for preparing an acoustic wave resonator, characterized in that: The method comprises: Providing an intermediate structure; the intermediate structure comprises, from bottom to top, a supporting substrate, an energy reflecting structure, a bottom electrode and a piezoelectric film; forming a piezoelectric failure region in the piezoelectric film based on a post-annealing method or an ion implantation method; wherein the piezoelectric failure region is formed in a partial region of the piezoelectric film; Disposing an interdigitated top electrode array on the piezoelectric active area; The width of the piezoelectric failure region is less than or equal to the width of the region not covered by the interdigitated top electrode array.

12. A filter, characterized in that: It comprises a plurality of resonators, wherein the resonators are the acoustic wave resonators according to any one of claims 1 to 10.

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