Acoustic resonator and preparation method thereof

Abstract

The invention provides an acoustic resonator and a preparation method thereof, which can be applied to the technical field of resonators. The acoustic wave resonator includes: a substrate; the first piezoelectric layer is arranged on the substrate and is used for coupling a plurality of sound waves, and the first piezoelectric layer is not patterned; the second piezoelectric layer comprises at least two piezoelectric structures, the at least two piezoelectric structures are arranged on the first piezoelectric layer, the at least two piezoelectric structures are used for exciting a plurality of sound waves under the action of a longitudinal electric field, and the second piezoelectric layer is patterned; the at least two interdigital electrodes are arranged on the second piezoelectric layer, the at least two interdigital electrodes are used for forming a longitudinal electric field, and the positions of the at least two interdigital electrodes correspond to the positions of the at least two piezoelectric structures in a one-to-one mode.

Description

Technical Field

[0001] The present disclosure relates to the technical field of resonators, and more specifically, to an acoustic wave resonator and a method for preparing the same. Background Art

[0002] With the advent of the 5G / 6G era, the rapid development of the Internet of Things and artificial intelligence has put forward higher requirements for data transmission capacity. In the field of mobile communications, traditional working frequency bands are mainly concentrated below 3GHz, resulting in very crowded spectrum resources. In order to alleviate this problem, high-frequency bands such as millimeter wave and centimeter wave bands provide abundant available spectrum resources, effectively supporting the capacity and transmission rate requirements of 5G.

[0003] Electromechanical coupling coefficient (k 2 ), as one of the important indicators to measure the performance of filters and resonators, a high electromechanical coupling coefficient can ensure that the filter and resonator have a sufficiently large passband bandwidth, thereby enabling the transmission of a larger amount of data. Therefore, in 5G / 6G, a resonator with a large electromechanical coupling coefficient is the key to realizing wide-bandwidth filters and resonators.

[0004] At present, acoustic wave resonators have become one of the most popular components in RF resonators due to their advantages such as small size, high frequency, low insertion loss, and large bandwidth. However, the relative bandwidth of acoustic wave resonators based on traditional surface acoustic waves (SAW) or film bulk acoustic wave resonators (FBAR) cannot achieve a major breakthrough, resulting in obvious fatigue of acoustic wave resonators in terms of large bandwidth. Related technologies usually achieve high electromechanical coupling coefficients based on the following methods: modal coupling, doping, polarization reversal piezoelectric film stacking, etc. However, these methods have problems such as complex preparation process and strict requirements on the size / line width of metal electrodes, and cannot be applied on a large scale. Therefore, how to improve the performance of acoustic wave resonators is an urgent problem that technicians in this field need to solve. Summary of the invention

[0005] In view of this, the present disclosure provides an acoustic wave resonator and a method for preparing the same.

[0006] According to one aspect of the present disclosure, there is provided an acoustic wave resonator, comprising: a substrate; a first piezoelectric layer, disposed on the substrate, for coupling a plurality of acoustic waves, wherein the first piezoelectric layer is not patterned; a second piezoelectric layer, comprising: at least two piezoelectric structures, the at least two piezoelectric structures being disposed on the first piezoelectric layer, the at least two piezoelectric structures being used to excite the plurality of acoustic waves under the action of a longitudinal electric field, wherein the second piezoelectric layer is patterned; at least two interdigitated electrodes, disposed on the second piezoelectric layer, the at least two interdigitated electrodes being used to form the longitudinal electric field, wherein the at least two interdigitated electrodes correspond one-to-one to the positions of the at least two piezoelectric structures.

[0007] For example, a chamfer formed between a side edge of the second piezoelectric layer and the first piezoelectric layer is greater than 0° and less than or equal to 90°.

[0008] For example, the thickness of the first piezoelectric layer is 1 nm-2000 nm; the thickness of the second piezoelectric layer is 1 nm-4000 nm.

[0009] For example, the line width of the interdigital electrodes is 10 nm - 100 um; the spacing between two adjacent interdigital electrodes is 10 nm - 100 um; the number of the interdigital electrodes is 2 - 1000;

[0010] The thickness of the above-mentioned interdigitated electrodes is 1 nm - 10 um.

[0011] For example, the first piezoelectric layer is bonded to the substrate.

[0012] For example, there is a cavity between the first piezoelectric layer and the substrate.

[0013] For example, the substrate includes a groove or the first piezoelectric layer includes a groove, and the groove is used to realize the cavity.

[0014] For example, the material of the above-mentioned interdigital electrodes is gold, silver, copper, aluminum, molybdenum, chromium, nickel, platinum, titanium, titanium aluminum, chromium gold, chromium aluminum, or an alloy of titanium, titanium aluminum, titanium copper, chromium gold, chromium aluminum, and chromium copper; the material of each piezoelectric layer in the above-mentioned first piezoelectric layer and the above-mentioned second piezoelectric layer is lithium niobate, lithium tantalate, aluminum nitride, scandium aluminum nitride, or each piezoelectric layer is a composite layer formed by at least two layers of a lithium niobate layer, an aluminum nitride layer, a scandium-doped aluminum nitride layer, a lithium tantalate layer, and a zinc oxide layer.

[0015] For example, the acoustic wave resonator includes a first temperature compensation layer disposed on a top layer of the acoustic wave resonator; and / or the acoustic wave resonator includes a second temperature compensation layer disposed between the substrate and the first piezoelectric layer.

[0016] According to another aspect of the present disclosure, a method for preparing the above-mentioned acoustic wave resonator is provided, comprising: forming a first piezoelectric layer on a substrate, wherein the above-mentioned first piezoelectric layer has not been patterned; forming a second piezoelectric layer on the above-mentioned first piezoelectric layer, wherein the above-mentioned second piezoelectric layer has been patterned and the above-mentioned second piezoelectric layer includes at least two piezoelectric structures; forming at least two interdigitated electrodes on the above-mentioned second piezoelectric layer to obtain an acoustic wave resonator, wherein the positions of the above-mentioned at least two interdigitated electrodes and the above-mentioned at least two piezoelectric structures correspond one-to-one.

[0017] According to the embodiments of the present disclosure, based on the second piezoelectric layer in the acoustic wave resonator including at least two piezoelectric structures, at least two piezoelectric structures are arranged on the first piezoelectric layer, at least two piezoelectric structures are used to excite multiple acoustic waves under the action of the longitudinal electric field, at least two interdigital electrodes are arranged on the second piezoelectric layer, at least two interdigital electrodes are used to form a longitudinal electric field, and the technical means of the one-to-one correspondence between the positions of the at least two interdigital electrodes and the at least two piezoelectric structures, compared with the traditional acoustic wave resonator capable of exciting a longitudinal electric field, it is possible to achieve an effect similar to adding a bottom electrode to the bottom surface of the piezoelectric material to generate a longitudinal electric field without adding a bottom electrode, thereby achieving a high electromechanical coupling coefficient. Since there is no bottom electrode, there is no need for a transfer bonding process, so the process is simple. And the second piezoelectric layer is grown on the first piezoelectric layer that has not been patterned, and the quality of the generated second piezoelectric layer is better than that of the second piezoelectric layer grown on the bottom electrode, thereby improving the quality factor of the acoustic wave resonator and improving the performance of the acoustic wave resonator. By coupling multiple sound waves based on the unpatterned first piezoelectric layer, the multiple sound waves can be enhanced, the energy conversion rate can be improved, and it is helpful to further improve the electromechanical coupling coefficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0019] Figure 1 Schematically shows a cross-sectional view of an acoustic wave resonator according to an embodiment of the present disclosure;

[0020] Figure 2A Schematically shows an admittance response diagram of an acoustic wave resonator according to an embodiment of the present disclosure;

[0021] Figure 2B Schematically showing a three-dimensional simulated vibration displacement diagram of an acoustic wave resonator according to an embodiment of the present disclosure;

[0022] Figure 3 Schematically shows an admittance response diagram of an acoustic wave resonator according to another embodiment of the present disclosure;

[0023] Figure 4ASchematically shows an admittance response diagram of an acoustic wave resonator according to another embodiment of the present disclosure;

[0024] Figure 4B Schematically showing a three-dimensional simulated vibration displacement diagram of an acoustic wave resonator according to another embodiment of the present disclosure;

[0025] Figure 5 Schematically shows an admittance response diagram of an acoustic wave resonator according to another embodiment of the present disclosure;

[0026] Fig. 6A Schematically shows a cross-sectional view of an acoustic wave resonator according to another embodiment of the present disclosure;

[0027] Figure 6B A schematic diagram schematically shows a chamfer formed between a side edge of the second piezoelectric layer and the first piezoelectric layer according to an embodiment of the present disclosure;

[0028] Figure 7 Schematically shows an admittance response diagram of an acoustic wave resonator according to another embodiment of the present disclosure;

[0029] Figure 8 Schematically shows a cross-sectional view of an acoustic wave resonator according to another embodiment of the present disclosure;

[0030] Fig. 9 Schematically shows a cross-sectional view of an acoustic wave resonator according to another embodiment of the present disclosure;

[0031] Fig.10 Schematically shows a cross-sectional view of an acoustic wave resonator according to another embodiment of the present disclosure;

[0032] Fig.11 Schematically shows a cross-sectional view of an acoustic wave resonator according to another embodiment of the present disclosure;

[0033] Fig.12 A schematic diagram schematically shows a method for preparing an acoustic wave resonator according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0034] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0035] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0036] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0037] When using expressions such as "at least one of A, B, and C, etc.", they should generally be interpreted according to the meaning of the expression commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0038] At present, acoustic wave resonators have received extensive attention in the RF industry due to their advantages such as small size, high frequency, low insertion loss, and large bandwidth. However, as the frequency of acoustic wave resonators continues to increase, the system's requirements for large bandwidth are also getting higher and higher. For example, the relative bandwidth (FBW, fractional band-width) required by the 5GNR (5th Generation New Radio, fifth generation new wireless technology) band exceeds 24% (n77 band, 3.3 GHz - 4.2 GHz), which requires the electromechanical coupling coefficient (k 2 ) reached 50%.

[0039] Traditional acoustic resonators that can achieve high electromechanical coupling coefficients require a bottom electrode to excite the longitudinal electric field. For example, the traditional thin film bulk acoustic resonator FBAR includes a substrate, a bottom electrode, a piezoelectric layer, and a top electrode from bottom to top. There are several problems with setting a bottom electrode in the FBAR: directly growing piezoelectric materials on the bottom electrode will affect the growth quality of the piezoelectric material, thereby reducing the quality factor of the resonator; growing the bottom electrode on the substrate based on the transfer bonding process will increase the process complexity, make patterning difficult, and increase the difficulty of bonding. FBAR mainly changes the resonant frequency of FBAR by adjusting the size / line width of the metal electrode, etc., and has strict requirements on the size / line width of the metal electrode.

[0040] Therefore, how to improve the performance of the acoustic wave resonator is an urgent problem to be solved by those skilled in the art.

[0041] In view of this, an embodiment of the present disclosure provides an acoustic wave resonator and a method for manufacturing the same, which can be applied in the field of resonator technology.

[0042] Figure 1 A schematic cross-sectional view of an acoustic wave resonator according to an embodiment of the present disclosure is shown schematically.

[0043] like Figure 1 As shown, the acoustic wave resonator 100 may include a substrate 110 , a first piezoelectric layer 120 , a second piezoelectric layer, and at least two interdigital electrodes 140 .

[0044] The first piezoelectric layer 120 may be disposed on the substrate 110. The first piezoelectric layer 120 is used to couple multiple sound waves. The first piezoelectric layer 120 is not patterned, that is, the first piezoelectric layer 120 is not processed by photolithography or etching.

[0045] The second piezoelectric layer may include at least two piezoelectric structures 131. At least two piezoelectric structures 131 may be disposed on the first piezoelectric layer 120. At least two piezoelectric structures 131 may be used to excite multiple sound waves under the action of a longitudinal electric field. The second piezoelectric layer has been patterned, i.e., the second piezoelectric layer has been processed by photolithography or etching, so that at least two piezoelectric structures 131 can be formed on the second piezoelectric layer. At least two piezoelectric structures 131 correspond to multiple sound waves one by one. Ideally, the frequencies of the multiple sound waves are the same.

[0046] The thickness of the at least two piezoelectric structures 131 may be the same or different. The width of the at least two piezoelectric structures 131 may be the same or different. The materials of the at least two piezoelectric structures 131 may be the same or different.

[0047] At least two interdigital electrodes 140 may be disposed on the second piezoelectric layer. The at least two interdigital electrodes 140 may be used to form a longitudinal electric field. The at least two interdigital electrodes 140 correspond to the positions of the at least two piezoelectric structures 131 one by one.

[0048] The width of the interdigital electrode 140 may be the same as or different from the width of the corresponding piezoelectric structure 131 .

[0049] According to the embodiments of the present disclosure, based on the second piezoelectric layer in the acoustic wave resonator including at least two piezoelectric structures, at least two piezoelectric structures are arranged on the first piezoelectric layer, at least two piezoelectric structures are used to excite multiple acoustic waves under the action of the longitudinal electric field, at least two interdigital electrodes are arranged on the second piezoelectric layer, at least two interdigital electrodes are used to form a longitudinal electric field, and the technical means of one-to-one correspondence between the positions of at least two interdigital electrodes and at least two piezoelectric structures, compared with the traditional acoustic wave resonator capable of exciting a longitudinal electric field, it is possible to achieve an effect similar to adding a bottom electrode to the bottom surface of the piezoelectric material to generate a longitudinal electric field without adding a bottom electrode, thereby achieving a high electromechanical coupling coefficient. Since there is no bottom electrode, there is no need for a transfer bonding process, so the process is simple. And the second piezoelectric layer is grown on the first piezoelectric layer that has not been patterned, and the quality of the generated second piezoelectric layer is better than that of the second piezoelectric layer grown on the bottom electrode, thereby improving the quality factor of the acoustic wave resonator and improving the performance of the acoustic wave resonator. By coupling multiple sound waves based on the unpatterned first piezoelectric layer, the multiple sound waves can be enhanced, the energy conversion rate can be improved, and it is helpful to further improve the electromechanical coupling coefficient.

[0050] According to an embodiment of the present disclosure, the acoustic wave resonator 100 can excite a piezoelectric coefficient e 3X (x=,1,2,3…6) sound waves, including but not limited to body sound waves and shear sound waves.

[0051] According to the embodiments of the present disclosure, the acoustic wave resonator 100 can adjust the resonant frequency of the acoustic wave resonator 100 only by changing the thickness of the second piezoelectric layer, or can adjust the resonant frequency of the acoustic wave resonator 100 only by changing the size / line width of the interdigital electrodes, or can adjust the resonant frequency of the acoustic wave resonator 100 by changing the thickness of the second piezoelectric layer and the size / line width of the interdigital electrodes.

[0052] A chamfer formed between a side edge of the second piezoelectric layer and the first piezoelectric layer is greater than 0° and less than or equal to 90°.

[0053] For example, the chamfer formed between the side edge of each piezoelectric structure 131 included in the second piezoelectric layer and the first piezoelectric layer 120 is greater than 0° and less than or equal to 0°, and the chamfer formed between the side edges of at least two piezoelectric structures 131 and the first piezoelectric layer 120 is the same.

[0054] For example, the chamfer may be 20°, 25°, 30°, 45°, 50°, 60°, 75°, 80°, or 90°.

[0055] According to the embodiments of the present disclosure, since the chamfer formed between the side edge of the second piezoelectric layer and the first piezoelectric layer is greater than 0° and less than or equal to 90°, compared with the traditional acoustic wave resonator that can excite the longitudinal electric field and maintain the chamfer between the side edge of the piezoelectric layer and the substrate at 90°, the requirements for processing and manufacturing the first piezoelectric layer can be reduced when manufacturing the second piezoelectric layer.

[0056] At least two piezoelectric structures 131 are evenly arranged along a first direction on the first piezoelectric layer 120 , wherein the first direction may be a direction from a first side edge of the first piezoelectric layer 120 to another side edge.

[0057] The thickness of the first piezoelectric layer 120 is 1 nm - 2000 nm. The thickness of the second piezoelectric layer is 1 nm - 4000 nm, that is, the thickness of each piezoelectric structure 131 is 1 nm - 4000 nm. The thickness of the first piezoelectric layer 120 and the thickness of the second piezoelectric layer may be the same or different.

[0058] For example, the thickness of the first piezoelectric layer 120 may be 1 nm, 25 nm, 50 nm, 100 nm, 125 nm, 150 nm, 200 nm, 300 nm, 500 nm, 600 nm, 800 nm, 900 nm, 1000 nm, 1200 nm, 1500 nm, 1800 nm, or 2000 nm. The thickness of the second piezoelectric layer may be 10 nm, 25 nm, 60 nm, 100 nm, 300 nm, 500 nm, 700 nm, 800 nm, 1000 nm, 1500 nm, 1800 nm, 2000 nm, 2500 nm, 3000 nm, 3500 nm, 3800 nm, or 4000 nm.

[0059] The line width of the interdigital electrodes 140 is 10 nm - 100 um. The spacing between two adjacent interdigital electrodes 140 is 10 nm - 100 um. The number of interdigital electrodes 140 is 2 - 1000. The thickness of the interdigital electrodes 140 is 1 nm - 10 um.

[0060] For example, the line width of the interdigital electrodes 140 can be 10nm, 100nm, 350nm, 500nm, 800nm, 1um, 5um, 8um, 10um, 30um, 60um, 90um or 100um. The spacing between two adjacent interdigital electrodes 140 can be 10nm, 200nm, 400nm, 650nm, 700nm, 900nm, 1um, 3um, 5um, 10um, 40um, 50um, 80um or 100um. The number of interdigital electrodes 140 can be 2, 10, 25, 50, 100, 150, 300, 400, 450, 500, 800, 900 or 1000. The thickness of the interdigital electrode 140 may be 1 nm, 5 nm, 10 nm, 50 nm, 100 nm, 200 nm, 450 nm, 600 nm, 1 um, 2 um, 4 um, 5 um, 8 um or 10 um.

[0061] The material of the interdigital electrodes 140 can be gold, silver, copper, aluminum, molybdenum, chromium, nickel, platinum, titanium gold, titanium aluminum, chrome gold, chrome aluminum, or an alloy of titanium gold, titanium aluminum, titanium copper, chrome gold, chrome aluminum, and chrome copper.

[0062] The material of each piezoelectric layer in the first piezoelectric layer 120 and the second piezoelectric layer can be lithium niobate, lithium tantalate, aluminum nitride, scandium aluminum nitride, or each piezoelectric layer is a composite layer formed by at least two layers of lithium niobate, aluminum nitride, scandium-doped aluminum nitride, lithium tantalate, and zinc oxide. The materials of the first piezoelectric layer 120 and the second piezoelectric layer can be the same or different.

[0063] The material of the substrate 110 may be silicon, silicon and silicon dioxide, sapphire, gallium nitride, silicon dioxide or silicon carbide.

[0064] According to an embodiment of the present disclosure, when the thickness of the second piezoelectric layer is 10 nm - 800 nm, the material of the second piezoelectric layer is lithium niobate, the thickness of the first piezoelectric layer 120 is 1 nm - 200 nm, the line width of the interdigital electrode 140 is 10 nm - 1000 nm, the spacing between two adjacent interdigital electrodes 140 is 10 nm - 1000 nm, the number of interdigital electrodes 140 is 2 - 500, and the thickness of the interdigital electrode 140 is 5 nm - 2000 nm, the resonant frequency of the resonator provided by an embodiment of the present disclosure is above 1 GHz, and the achieved electromechanical coupling coefficient is above 50%.

[0065] For example, the material of the second piezoelectric layer and the material of the first piezoelectric layer 120 in the acoustic wave resonator 100 can both be lithium niobate, the tangent direction can be X tangent direction, the thickness of the second piezoelectric layer can be 200 nm, the thickness of the first piezoelectric layer 120 can be 100 nm, the material of the interdigital electrode 140 can be gold, the line width of the interdigital electrode 140 can be 1 um, the spacing between two adjacent interdigital electrodes 140 can be 1 um, the thickness of the interdigital electrode 140 can be 40 nm, the number of interdigital electrodes 140 can be 2, the material of the substrate 110 can be silicon, and the chamfer can be 90°. The admittance response diagram of the acoustic wave resonator 100 of this embodiment is shown in FIG. Figure 2A As shown, the three-dimensional simulated vibration displacement diagram of the acoustic wave resonator 100 is as shown in Figure 2B shown.

[0066] Figure 2A The diagram schematically shows an admittance response diagram of an acoustic wave resonator according to an embodiment of the present disclosure. Figure 2B A three-dimensional simulated vibration displacement diagram of an acoustic wave resonator according to an embodiment of the present disclosure is schematically shown.

[0067] exist Figure 2A In the figure, the horizontal axis is frequency in GHz. The vertical axis is admittance in dB. s is the resonant frequency. p is the anti-resonance frequency. k 2 is the electromechanical coupling coefficient. The solid line is the simulation result. The dotted line is the fitting result.

[0068] Depend on Figure 2A It can be seen that the embodiments of the present disclosure can achieve a resonant frequency f s is 2.58GHz, and the electromechanical coupling coefficient k 2 The ultra-large bandwidth acoustic wave resonator 100 is 84.5%. The acoustic wave resonator 100 can well meet the performance requirements of high resonant frequency, high bandwidth, and high electromechanical coupling coefficient of the resonator in the current 5G frequency band.

[0069] exist Figure 2B In the figure, the vibration is decomposed (see the arrows), and it can be seen that the vibration displacement consists of two parts, namely longitudinal vibration and lateral vibration. Figure 2B It can be seen that the two piezoelectric structures 131 can excite multiple acoustic waves under the action of the longitudinal electric field, which can be multiple longitudinal waves. The first piezoelectric layer 120 can excite transverse waves under the action of the transverse electric field formed by at least two interdigitated electrodes 140, and can couple multiple longitudinal waves. In this way, a case of multiple wave coupled vibrations, which includes both longitudinal waves and transverse waves (see various arrows), is achieved.

[0070] For example, the material of the second piezoelectric layer and the material of the first piezoelectric layer 120 in the acoustic wave resonator 100 can both be lithium niobate, the tangent direction can be X tangent direction, the thickness of the second piezoelectric layer can be 100 nm, the thickness of the first piezoelectric layer 120 can be 100 nm, the material of the interdigital electrode 140 can be gold, the line width of the interdigital electrode 140 can be 1um, the spacing between two adjacent interdigital electrodes 140 can be 1um, the thickness of the interdigital electrode 140 can be 40nm, the number of interdigital electrodes 140 can be 2, the material of the substrate 110 can be silicon, and the chamfer can be 90°. The admittance response diagram of the acoustic wave resonator 100 of this embodiment is shown in FIG. Figure 3 shown.

[0071] Figure 3 The figure schematically shows an admittance response diagram of an acoustic wave resonator according to another embodiment of the present disclosure.

[0072] exist Figure 3 In the figure, the horizontal axis is frequency in GHz. The vertical axis is admittance in dB. s is the resonant frequency. p is the anti-resonance frequency. k 2 is the electromechanical coupling coefficient. The solid line is the simulation result. The dotted line is the fitting result.

[0073] Depend on Figure 3 It can be seen that the embodiments of the present disclosure can achieve a resonant frequency f s is 3.92GHz, and the electromechanical coupling coefficient k 2 The ultra-large bandwidth acoustic wave resonator 100 is 64%. The acoustic wave resonator 100 can well meet the performance requirements of high resonant frequency, high bandwidth, and high electromechanical coupling coefficient of the resonator in the current 5G frequency band.

[0074] For example, the material of the second piezoelectric layer and the material of the first piezoelectric layer 120 in the acoustic wave resonator 100 can both be aluminum scandium nitride (AlScN), the proportion of Al is 0.6, that is, Al / (Al+Sc)=0.6, the proportion of Sc is 0.4, that is, Sc / (Al+Sc)=0.4, the thickness of the second piezoelectric layer can be 200 nm, the thickness of the first piezoelectric layer 120 can be 100 nm, the material of the interdigital electrode 140 can be gold, the line width of the interdigital electrode 140 can be 1um, the spacing between two adjacent interdigital electrodes 140 can be 1um, the thickness of the interdigital electrode 140 can be 40nm, the number of interdigital electrodes 140 can be 2, the material of the substrate 110 can be silicon, and the chamfer can be 90°. The admittance response diagram of the acoustic wave resonator 100 of this embodiment is shown in FIG. Figure 4A As shown, the three-dimensional simulated vibration displacement diagram of the acoustic wave resonator 100 is as shown in Figure 4B shown.

[0075] Figure 4A The figure schematically shows an admittance response diagram of an acoustic wave resonator according to another embodiment of the present disclosure. Figure 4B A three-dimensional simulated vibration displacement diagram of an acoustic wave resonator according to another embodiment of the present disclosure is schematically shown.

[0076] exist Figure 4A In the figure, the horizontal axis is frequency in GHz. The vertical axis is admittance in dB. s is the resonant frequency. p is the anti-resonance frequency. k 2 is the electromechanical coupling coefficient. The solid line is the simulation result. The dotted line is the fitting result.

[0077] Depend on Figure 4A It can be seen that the embodiments of the present disclosure can achieve a resonant frequency f s is 4.98GHz, and the electromechanical coupling coefficient k 2 The wide bandwidth acoustic wave resonator 100 is 24.36%. Compared with the conventional FBAR / BAW including metal-piezoelectric material-metal (bottom electrode), the same performance can be achieved without the need for a bottom electrode. Figure 4B It can be seen that the two piezoelectric structures 131 included in the second piezoelectric layer in the acoustic wave resonator 100 excite longitudinal waves, and the first piezoelectric layer 120 can excite transverse waves and can couple multiple longitudinal waves, so that the acoustic wave resonator 100 has a higher resonance frequency and can well meet the future high-frequency application requirements.

[0078] For example, the material of the second piezoelectric layer in the acoustic wave resonator 100 may be aluminum scandium nitride (AlScN), the proportion of Al is 0.6, that is, Al / (Al+Sc)=0.6, the proportion of Sc is 0.4, that is, Sc / (Al+Sc)=0.4, the thickness of the second piezoelectric layer may be 100 nm, the material of the first piezoelectric layer 120 may be lithium niobate LN, the thickness of the first piezoelectric layer 120 may be 50 nm, the material of the interdigital electrode 140 may be gold, the line width of the interdigital electrode 140 may be 1um, the spacing between two adjacent interdigital electrodes 140 may be 1um, the thickness of the interdigital electrode 140 may be 40nm, the number of interdigital electrodes 140 may be 2, the material of the substrate 110 may be silicon, and the chamfer may be 90°. The admittance response diagram of the acoustic wave resonator 100 of this embodiment is shown in FIG. Figure 5 shown.

[0079] Figure 5 The figure schematically shows an admittance response diagram of an acoustic wave resonator according to another embodiment of the present disclosure.

[0080] exist Figure 5 In the figure, the horizontal axis is frequency in GHz. The vertical axis is admittance in dB. sis the resonant frequency. p is the anti-resonance frequency. k 2 is the electromechanical coupling coefficient. The solid line is the simulation result. The dotted line is the fitting result.

[0081] Depend on Figure 5 It can be seen that the embodiments of the present disclosure can achieve a resonant frequency f s is 7.07GHz, and the electromechanical coupling coefficient k 2 The wide bandwidth acoustic wave resonator 100 is 26%. Compared with the conventional FBAR / BAW including metal-piezoelectric material-metal (bottom electrode), the same performance can be achieved without the need for a bottom electrode.

[0082] The two piezoelectric structures 131 included in the second piezoelectric layer in the acoustic wave resonator 100 excite longitudinal waves, and the first piezoelectric layer 120 can excite transverse waves and can couple multiple longitudinal waves, so that the acoustic wave resonator 100 has a higher resonance frequency and can well meet future high-frequency application requirements.

[0083] For example, the material of the second piezoelectric layer and the material of the first piezoelectric layer 120 in the acoustic wave resonator 100 can both be aluminum scandium nitride (AlScN), the proportion of Al is 0.6, that is, Al / (Al+Sc)=0.6, the proportion of Sc is 0.4, that is, Sc / (Al+Sc)=0.4, the thickness of the second piezoelectric layer can be 200 nm, the thickness of the first piezoelectric layer 120 can be 100 nm, the material of the interdigital electrode 140 can be gold, the line width of the interdigital electrode 140 can be 5um, the spacing between two adjacent interdigital electrodes 140 can be 3um, the thickness of the interdigital electrode 140 can be 40nm, the number of interdigital electrodes 140 can be 2, the material of the substrate 110 can be silicon, and the chamfer can be 90°. The resonant frequency f of the acoustic wave resonator 100 of this embodiment is s The acoustic wave resonator 100 excites longitudinal waves, has a higher resonance frequency, and can well meet the future high-frequency application requirements.

[0084] Fig. 6A A cross-sectional view of an acoustic wave resonator according to another embodiment of the present disclosure is schematically shown. Figure 6B The diagram schematically shows a chamfer formed between the side edge of the second piezoelectric layer and the first piezoelectric layer according to an embodiment of the present disclosure.

[0085] like Fig. 6A As shown, the acoustic wave resonator 600 may include a substrate 610, a first piezoelectric layer 620, a second piezoelectric layer and at least two interdigital electrodes 640. The second piezoelectric layer may include at least two piezoelectric structures 631. Fig. 6AThe substrate 610, the first piezoelectric layer 620 and at least two interdigital electrodes 640 are respectively connected to Figure 1 The substrate 110, the first piezoelectric layer 120 and the at least two interdigital electrodes 140 have similar structures and functions, and for the sake of simplicity, they are not described again here.

[0086] Fig. 6A The acoustic wave resonator 600 and Figure 1 The difference between the acoustic wave resonator 100 in FIG. 1 is that the chamfer formed between the side edge of the second piezoelectric layer and the first piezoelectric layer is different.

[0087] exist Figure 1 In the embodiment, a chamfer formed between a side edge of the second piezoelectric layer and the first piezoelectric layer 120 may be equal to 90°.

[0088] like Figure 6B As shown, the chamfer θ formed between the side edge of the second piezoelectric layer and the first piezoelectric layer 620 is 45°, that is, the chamfer formed between each piezoelectric structure 631 and the first piezoelectric layer 620 is 45°.

[0089] For example, the material of the second piezoelectric layer and the material of the first piezoelectric layer 620 in the acoustic wave resonator 600 can both be lithium niobate, the tangent direction can be X tangent direction, the thickness of the second piezoelectric layer can be 200 nm, the thickness of the first piezoelectric layer 620 can be 100 nm, the material of the interdigital electrode 640 can be gold, the line width of the interdigital electrode 640 can be 1um, the spacing between two adjacent interdigital electrodes 640 can be 1um, the thickness of the interdigital electrode 640 can be 40nm, the number of interdigital electrodes 640 can be 2, the material of the substrate 610 can be silicon, and the chamfer can be 45°. The admittance response diagram of the acoustic wave resonator 600 of this embodiment is shown in FIG. Figure 7 shown.

[0090] Figure 7 The figure schematically shows an admittance response diagram of an acoustic wave resonator according to another embodiment of the present disclosure.

[0091] exist Figure 7 In the figure, the horizontal axis is frequency in GHz. The vertical axis is admittance in dB. s is the resonant frequency. p is the anti-resonance frequency. k 2 is the electromechanical coupling coefficient. The solid line is the simulation result. The dotted line is the fitting result.

[0092] Depend on Figure 7 It can be seen that the embodiments of the present disclosure can achieve a resonant frequency f s is 3.11GHz, and the electromechanical coupling coefficient k 2The ultra-large bandwidth acoustic wave resonator 500 is 74%. The acoustic wave resonator 500 can well meet the performance requirements of high resonant frequency, high bandwidth, and high electromechanical coupling coefficient of the resonator in the current 5G frequency band.

[0093] Based on Figure 1 The acoustic wave resonator 100 in the embodiment corresponding to Fig. 6A It can be seen from the embodiment corresponding to the acoustic wave resonator 600 in the figure that the acoustic wave resonator provided by the embodiment of the present disclosure can achieve a high electromechanical coupling coefficient at any chamfer angle of 0°-90°.

[0094] Figure 8 A cross-sectional view of an acoustic wave resonator according to another embodiment of the present disclosure is schematically shown.

[0095] like Figure 8 As shown, the acoustic wave resonator 800 may include a substrate 810, a first piezoelectric layer 820, a second piezoelectric layer and at least two interdigital electrodes 840. The second piezoelectric layer may include at least two piezoelectric structures 831. Figure 8 The first piezoelectric layer 820, the second piezoelectric layer and at least two interdigitated electrodes 840 are respectively connected to Figure 1 The first piezoelectric layer 120, the second piezoelectric layer and the at least two interdigital electrodes 140 have similar structures and functions, which will not be described in detail for simplicity.

[0096] Figure 8 The acoustic resonator 800 and Figure 1 The difference of the acoustic wave resonator 100 is that: Figure 1 The first piezoelectric layer 120 and the substrate 110 are bonded together, Figure 8 There is a cavity between the first piezoelectric layer 820 and the substrate 810.

[0097] For example, the substrate 810 may include a groove 811, and the groove 811 is used to realize a cavity. Alternatively, the first piezoelectric layer 820 includes a groove, and the groove is used to realize a cavity.

[0098] For example, the substrate 810 may be etched based on dry etching, so as to release the acoustic wave resonator 800 from the substrate 810. Dry etching can more accurately control the release degree of the acoustic wave resonator 800, so as to achieve the effect of completely suspending the device.

[0099] According to an embodiment of the present disclosure, when there is a cavity between the first piezoelectric layer 820 and the substrate 810 , the quality factor of the acoustic wave resonator 800 can be improved, thereby improving the performance of the acoustic wave resonator 800 .

[0100] Fig. 9A cross-sectional view of an acoustic wave resonator according to another embodiment of the present disclosure is schematically shown.

[0101] like Fig. 9 As shown, the acoustic wave resonator 900 may include a substrate 910, a first piezoelectric layer 920, a second piezoelectric layer, at least two interdigitated electrodes 940, and a first temperature compensation layer 950. The second piezoelectric layer may include at least two piezoelectric structures 931. Fig. 9 The substrate 910, the first piezoelectric layer 920, the second piezoelectric layer and at least two interdigitated electrodes 940 are respectively connected to Figure 1 The substrate 110, the first piezoelectric layer 120, the second piezoelectric layer and the at least two interdigital electrodes 140 have similar structures and functions, and for the sake of simplicity, they are not described again here.

[0102] The first temperature compensation layer 950 is disposed on the top layer of the acoustic wave resonator 900 .

[0103] According to the embodiment of the present disclosure, the first temperature compensation layer 950 can effectively eliminate the influence of temperature change on the acoustic wave resonator 900 and improve the stability and accuracy of the acoustic wave resonator 900 .

[0104] Fig.10 A cross-sectional view of an acoustic wave resonator according to another embodiment of the present disclosure is schematically shown.

[0105] like Fig.10 As shown, the acoustic wave resonator 1000 may include a substrate 1010, a first piezoelectric layer 1020, a second piezoelectric layer, at least two interdigitated electrodes 1040, and a second temperature compensation layer 1060. The second piezoelectric layer may include at least two piezoelectric structures 1031. Fig.10 The substrate 1010, the first piezoelectric layer 1020, the second piezoelectric layer and at least two interdigitated electrodes 1040 are respectively connected to Figure 1 The substrate 110, the first piezoelectric layer 120, the second piezoelectric layer and the at least two interdigital electrodes 140 have similar structures and functions, and for the sake of simplicity, they are not described again here.

[0106] The second temperature compensation layer 1060 is disposed between the substrate 1010 and the first piezoelectric layer 1020 .

[0107] According to the embodiments of the present disclosure, the second temperature compensation layer 1060 can effectively eliminate the influence of temperature change on the acoustic wave resonator 1000 , thereby improving the stability and accuracy of the acoustic wave resonator 1000 .

[0108] Fig.11 A cross-sectional view of an acoustic wave resonator according to another embodiment of the present disclosure is schematically shown.

[0109] like Fig.11As shown, the acoustic wave resonator 1100 may include a substrate 1110, a first piezoelectric layer 1120, a second piezoelectric layer, at least two interdigitated electrodes 1140, a first temperature compensation layer 1150, and a second temperature compensation layer 1160. The second piezoelectric layer may include at least two piezoelectric structures 1131. Fig.11 The substrate 1110, the first piezoelectric layer 1120, the second piezoelectric layer and at least two interdigitated electrodes 1140 are respectively connected to Figure 1 The substrate 110, the first piezoelectric layer 120, the second piezoelectric layer and the at least two interdigital electrodes 140 have similar structures and functions, and for the sake of simplicity, they are not described again here.

[0110] The first temperature compensation layer 1150 is disposed on the top layer of the acoustic wave resonator 1100. The second temperature compensation layer 1160 is disposed between the substrate 1110 and the first piezoelectric layer 1120. The material of each temperature compensation layer may be silicon dioxide (SiO2).

[0111] According to the embodiments of the present disclosure, the first temperature compensation layer 1150 and the second temperature compensation layer 1160 can effectively eliminate the influence of temperature change on the acoustic wave resonator 1100 , thereby improving the stability and accuracy of the acoustic wave resonator 1100 .

[0112] According to the embodiments of the present disclosure, the acoustic wave resonator provided by the embodiments of the present disclosure has an electromechanical coupling coefficient of more than 20%, which is far higher than the traditional FBAR resonator and fully meets the performance requirements of the filter in the current 5G and 6G frequency bands.

[0113] Fig.12 A flowchart of a method for preparing an acoustic wave resonator according to an embodiment of the present disclosure is schematically shown. Fig.12 The acoustic wave resonator preparation method in the present disclosure is used to prepare each acoustic wave resonator provided in the embodiment of the present disclosure.

[0114] like Fig.12 As shown, the method for preparing an acoustic wave resonator may include operations S1210 to S1230.

[0115] In operation S1210, a first piezoelectric layer is formed on a substrate, wherein the first piezoelectric layer is not patterned.

[0116] In operation S1220, a second piezoelectric layer is formed on the first piezoelectric layer, wherein the second piezoelectric layer has been patterned and includes at least two piezoelectric structures.

[0117] In operation S1230, at least two interdigital electrodes are formed on the second piezoelectric layer to obtain an acoustic wave resonator, wherein the at least two interdigital electrodes correspond to the positions of the at least two piezoelectric structures in a one-to-one manner.

[0118] For example, a first piezoelectric film may be formed on the substrate first, and then the first piezoelectric layer may be formed. The first piezoelectric film may be formed by any one of ion implantation transfer, sputtering deposition, molecular beam epitaxial deposition, and vapor phase epitaxial growth deposition.

[0119] Then, a second piezoelectric film is formed on the first piezoelectric layer, and the second piezoelectric film is etched by inductively coupled plasma etching to pattern the second piezoelectric film to obtain a second piezoelectric layer, and the second piezoelectric layer includes at least two piezoelectric structures. The second piezoelectric film can be formed by any one of ion implantation transfer, sputtering deposition, molecular beam epitaxial deposition, and vapor phase epitaxial growth deposition.

[0120] Then, one or more layers of metal are deposited on the second piezoelectric layer by electron beam evaporation or magnetron sputtering, and at least two interdigital electrodes are formed by a lift-off process.

[0121] According to an embodiment of the present disclosure, in operation S1210, forming a first piezoelectric layer on a substrate may include: forming a second temperature compensation layer on the substrate, and forming the first piezoelectric layer on the second temperature compensation layer. The method for preparing an acoustic wave resonator may also include, before operation S1220, forming a groove on the substrate, or, in operation S1220, forming a first piezoelectric layer on the substrate, the first piezoelectric layer including a groove. Forming at least two interdigital electrodes on the second piezoelectric layer to obtain an acoustic wave resonator includes: forming at least two interdigital electrodes on the second piezoelectric layer; forming a first temperature compensation layer on the top layer to obtain an acoustic wave resonator.

[0122] According to an embodiment of the present disclosure, when the substrate includes a groove, the substrate may be released by a dry release method or a wet release method before operation S1220 to form a groove between the substrate and the first piezoelectric layer, and the groove is used to realize a cavity.

[0123] It will be appreciated by those skilled in the art that the features described in the various embodiments and / or claims of the present disclosure may be combined and / or combined in a variety of ways, even if such combinations and / or combinations are not explicitly described in the present disclosure. In particular, the features described in the various embodiments and / or claims of the present disclosure may be combined and / or combined in a variety of ways without departing from the spirit and teachings of the present disclosure. All of these combinations and / or combinations fall within the scope of the present disclosure.

[0124] The embodiments of the present disclosure are described above. However, these embodiments are only for illustrative purposes and are not intended to limit the scope of the present disclosure. Although the embodiments are described above separately, this does not mean that the measures in the various embodiments cannot be used in combination to advantage. The scope of the present disclosure is defined by the attached claims and their equivalents. Without departing from the scope of the present disclosure, those skilled in the art may make a variety of substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. An acoustic wave resonator, comprising: substrate; A first piezoelectric layer, disposed on the substrate, for coupling a plurality of acoustic waves, wherein the first piezoelectric layer is not patterned; The second piezoelectric layer comprises: At least two piezoelectric structures, the at least two piezoelectric structures are arranged on the first piezoelectric layer, and the at least two piezoelectric structures are used to excite the multiple sound waves under the action of a longitudinal electric field, wherein the second piezoelectric layer is patterned; At least two interdigital electrodes are disposed on the second piezoelectric layer, and the at least two interdigital electrodes are used to form the longitudinal electric field, wherein the positions of the at least two interdigital electrodes and the at least two piezoelectric structures correspond one to one.

2. The acoustic wave resonator according to claim 1, wherein A chamfer formed between a side edge of the second piezoelectric layer and the first piezoelectric layer is greater than 0° and less than or equal to 90°.

3. The acoustic wave resonator according to claim 1 or 2, wherein: The thickness of the first piezoelectric layer is 1 nm - 2000 nm; The thickness of the second piezoelectric layer is 1 nm - 4000 nm.

4. The acoustic wave resonator according to claim 3, wherein: The line width of the interdigital electrodes is 10 nm - 100 um; The distance between two adjacent interdigital electrodes is 10 nm – 100 um; The number of the interdigital electrodes is 2-1000; The thickness of the interdigital electrodes is 1 nm - 10 um.

5. The acoustic wave resonator according to claim 1 or 2, wherein: The first piezoelectric layer is bonded to the substrate.

6. The acoustic wave resonator according to claim 1 or 2, wherein: There is a cavity between the first piezoelectric layer and the substrate.

7. The acoustic wave resonator according to claim 6, wherein: The substrate includes a groove or the first piezoelectric layer includes a groove, and the groove is used to realize the cavity.

8. The acoustic wave resonator according to claim 1 or 4, wherein: The material of the interdigital electrodes is gold, silver, copper, aluminum, molybdenum, chromium, nickel, platinum, titanium, titanium aluminum, chromium gold, chromium aluminum, or an alloy of titanium, titanium aluminum, titanium copper, chromium gold, chromium aluminum, and chromium copper; The material of each piezoelectric layer in the first piezoelectric layer and the second piezoelectric layer is lithium niobate, lithium tantalate, aluminum nitride, scandium aluminum nitride, or each piezoelectric layer is a composite layer formed by at least two layers of the lithium niobate layer, aluminum nitride layer, scandium-doped aluminum nitride layer, lithium tantalate layer and zinc oxide layer.

9. The acoustic wave resonator according to claim 8, wherein: The acoustic wave resonator comprises a first temperature compensation layer disposed on a top layer of the acoustic wave resonator; and / or The acoustic wave resonator includes a second temperature compensation layer disposed between the substrate and the first piezoelectric layer.

10. A method for preparing the acoustic wave resonator according to any one of claims 1 to 9, comprising: forming a first piezoelectric layer on a substrate, wherein the first piezoelectric layer is not patterned; forming a second piezoelectric layer on the first piezoelectric layer, wherein the second piezoelectric layer has been patterned and includes at least two piezoelectric structures; At least two interdigital electrodes are formed on the second piezoelectric layer to obtain an acoustic wave resonator, wherein the positions of the at least two interdigital electrodes correspond one-to-one to the positions of the at least two piezoelectric structures.

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