Acoustic wave resonator and electronic device

Abstract

Disclosed in the present application are an acoustic wave resonator and an electronic device. The acoustic wave resonator comprises: a substrate, which has a first surface and a second surface arranged opposite each other; a piezoelectric layer, which is arranged on the first surface, wherein the piezoelectric layer comprises a first lithium niobate layer, the tangential direction of the first lithium niobate layer is perpendicular to the direction X of a first crystal axis, and a YZ plane is arranged opposite the first surface; and an interdigital electrode, which is arranged on a surface of the side of the piezoelectric layer facing away from the substrate, and which has a plurality of strip electrodes sequentially arranged, wherein the strip electrodes extend in a first direction, a second direction is perpendicular to the first direction and is parallel to the YZ plane, there is an Euler angle of -90° to -20° between the second direction and the direction Y of a second crystal axis, and the ratio of the periodic wavelength of the interdigital electrode of the acoustic wave resonator to the thickness of the piezoelectric layer of the acoustic wave resonator is not less than 0.2 and not greater than 4, such that an electric field formed by the interdigital electrode can excite the piezoelectric layer to form a coupled acoustic wave mode by means of the combined action of at least two piezoelectric coefficients.

Description

Acoustic wave resonator and electronic device

[0001] This application claims priority to the Chinese patent application No. 2024104466574, filed on April 12, 2024, and entitled "Acoustic wave resonator and electronic device", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the technical field of acoustic wave resonators, and more particularly, to an acoustic wave resonator and an electronic device. BACKGROUND

[0003] In the development process of 2G, 3G and 4G communication technologies, people have allocated spectrum resources that are easy to deploy and achieve wide coverage for communication networks. According to the provisions of the 3GPP 38.101 protocol, 5G NR mainly uses two frequency bands: FR1 and FR2. The frequency range of FR1 is 450MHz-6GHz, also known as the Sub-6GHz frequency band; the frequency range of FR2 is 24.25GHz-52.6GHz, which is usually referred to as the millimeter wave frequency band. Due to the advantages of the frequency band below 6GHz in wide area coverage, this part of the spectrum resource is widely used, and there are even some spectrum conflicts.

[0004] In order to better build 5G network communication and meet the demand of 5G for large bandwidth spectrum resources and high data transmission rate, major manufacturers have set their sights on the millimeter wave frequency band. Since the radio frequency filter is an indispensable component in the radio frequency front-end architecture, it not only needs to adapt to the higher working frequency of the millimeter wave frequency band, but also needs to provide a larger bandwidth to enhance the processing efficiency and capacity of the entire system to signals.

[0005] In the field of radio frequency filtering, acoustic wave filters are widely welcomed due to their small size, high frequency, low insertion loss and large bandwidth. With the continuous increase of frequency, when entering the millimeter wave frequency band, the demand for bandwidth of the system is also increasing. For example, in the n257 frequency band (26.5GHz-29.5GHz) of the FR2 frequency band, the required relative bandwidth FBW has exceeded 10%, which puts higher requirements on the electromechanical coupling coefficient of the acoustic wave resonator used to build the acoustic wave filter. In the face of this challenge, the filter based on the traditional acoustic wave resonator (such as a thin film bulk acoustic wave resonator) has encountered technical bottlenecks in expanding the relative bandwidth. Therefore, how to improve the performance of the acoustic wave resonator working in the millimeter wave frequency band is a difficult problem that needs to be solved by those skilled in the art.

[0006] SUMMARY

[0007] Therefore, the present application provides an acoustic wave resonator and an electronic device, as follows:

[0008] An acoustic wave resonator, comprising:

[0009] a substrate having a first surface and a second surface arranged oppositely;

[0010] a piezoelectric layer arranged on the first surface; the piezoelectric layer comprises a first lithium niobate layer, the piezoelectric layer has a first crystal axis X, a second crystal axis Y and a third crystal axis Z perpendicular to each other; a cut direction of the first lithium niobate layer is perpendicular to the first crystal axis X; a YZ plane is arranged oppositely to the first surface;

[0011] an interdigital electrode arranged on a side surface of the piezoelectric layer away from the substrate; the interdigital electrode has a plurality of strip electrodes arranged sequentially; the strip electrodes extend along a first direction; a second direction is perpendicular to the first direction and parallel to the YZ plane;

[0012] wherein the second direction and the second crystal axis Y have an Euler angle of -90° to -20°, and a ratio of a periodic wavelength of the interdigital electrode of the acoustic wave resonator to a thickness of the piezoelectric layer is not less than 0.2 and not more than 4, so that an electric field formed by the interdigital electrode can excite a coupled acoustic wave mode formed by at least two piezoelectric coefficients in the piezoelectric layer, the at least two piezoelectric coefficients comprising at least one longitudinal piezoelectric coefficient and at least one shear piezoelectric coefficient.

[0013] Optionally, in the acoustic wave resonator, the first surface has a functional structure for adjusting a resonance performance of an acoustic wave in the piezoelectric layer.

[0014] Optionally, in the acoustic wave resonator, the thickness of the piezoelectric layer is in a range of 10 nm to 5000 nm.

[0015] Optionally, in the acoustic wave resonator, the piezoelectric layer is a single-layer first lithium niobate layer, the Euler angle is -50°, the periodic wavelength of the interdigital electrode is 500 nm, the thickness of the piezoelectric layer is 400 nm, and the ratio is 1.25.

[0016] Or, the piezoelectric layer is a single-layer first lithium niobate layer, the Euler angle is -45°, the periodic wavelength of the interdigital electrode is 500 nm, the thickness of the piezoelectric layer is 400 nm, and the ratio is 1.25.

[0017] Or, the piezoelectric layer is a single-layer first lithium niobate layer, the Euler angle is -55°, the periodic wavelength of the interdigital electrode is 140 nm, the thickness of the piezoelectric layer is 400 nm, and the ratio is 0.35.

[0018] Optionally, in the acoustic wave resonator, at least one resonance auxiliary layer is arranged between the first lithium niobate layer and the substrate, and / or at least one resonance auxiliary layer is arranged between the first lithium niobate layer and the interdigital electrode, the resonance auxiliary layer is used to adjust the resonance performance of the acoustic wave in the piezoelectric layer.

[0019] Optionally, in the above acoustic wave resonator, the resonant auxiliary layer is any one of a second lithium niobate layer, a lithium tantalate layer, an aluminum nitride layer, a scandium-doped aluminum nitride layer, and a zinc oxide layer.

[0020] The second lithium niobate layer and the first lithium niobate layer have different tangential directions.

[0021] Optionally, in the above acoustic wave resonator, the material of the interdigital electrode is one or an alloy formed by multiple of tungsten, platinum, gold, silver, copper, aluminum, molybdenum, chromium, nickel, and titanium.

[0022] Optionally, in the above acoustic wave resonator, the substrate is any one of a silicon carbide substrate, a sapphire substrate, a gallium nitride substrate, and a silicon substrate.

[0023] Optionally, in the above acoustic wave resonator, the number of the strip electrodes in the interdigital electrode is 2-500.

[0024] The thickness of the strip electrode is 5-500 nm.

[0025] The width of the strip electrode is 0.001-5 μm.

[0026] The length of the strip electrode is 1-500 μm.

[0027] The application further provides an electronic device comprising the above acoustic wave resonator.

[0028] As described above, the technical scheme of the application sets the piezoelectric layer in the acoustic wave resonator to comprise a first lithium niobate layer, the tangential direction of the first lithium niobate layer is perpendicular to the first crystal axis X, i.e., the first lithium niobate layer is X-cut lithium niobate (or X-cut lithium niobate), the vertical direction (second direction) of the extension direction of the strip electrode has an Euler angle of -90°- -20° with the second crystal axis Y, and the ratio of the periodic wavelength of the interdigital electrode of the acoustic wave resonator to the thickness of the piezoelectric layer is not less than 0.2 and not greater than 4. In this way, the electric field formed by the interdigital electrode can excite the piezoelectric layer to form a coupled acoustic wave mode acted on by at least two piezoelectric coefficients, including at least one longitudinal piezoelectric coefficient and at least one shear piezoelectric coefficient, so that the working frequency of the resonator is 3-30 GHz or above 30 GHz, and the electromechanical coupling coefficient is greater than 6%, and the performance of the acoustic wave resonator working in the millimeter wave frequency band can be improved.

[0029] Further, the working frequency and the electromechanical coupling coefficient of the acoustic wave resonator can be adjusted by adjusting the Euler angle and / or the ratio of the periodic wavelength of the interdigital electrode to the thickness of the piezoelectric layer, so as to optimize the working frequency and the electromechanical coupling coefficient of the acoustic wave resonator, and better meet the high frequency and large bandwidth requirements of the filter in the millimeter wave communication frequency band. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are merely embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without any creative work.

[0031] The structures, proportions, sizes, etc. depicted in the drawings of this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with this technology. They are not intended to limit the conditions under which this application can be implemented, and therefore have no substantive technical significance. Any structural modifications, changes in proportional relationships, or adjustments in size, without affecting the efficacy and objectives that can be achieved by this application, should still fall within the scope of the technical contents disclosed in this application.

[0032] FIG1 is a top view of an acoustic wave resonator provided in an embodiment of the present application;

[0033] FIG2 is a cross-sectional view of the acoustic wave resonator shown in FIG1 ;

[0034] FIG3 is a three-dimensional schematic diagram of the rotation of the Euler angle α of an acoustic wave resonator provided in an embodiment of the present application;

[0035] FIG4 is a cross-sectional view of an ultra-high frequency, wide bandwidth acoustic wave resonator having a ratio of the periodic wavelength of the interdigital electrodes to the thickness of the piezoelectric layer of 1.25, provided in an embodiment of the present application;

[0036] FIG5 is a schematic diagram of the cross-sectional polarization displacement of an ultra-high frequency, wide bandwidth acoustic wave resonator in which a shear piezoelectric coefficient and a longitudinal piezoelectric coefficient act together when the ratio of the periodic wavelength of the interdigitated electrode to the thickness of the piezoelectric layer is 1.25, provided in an embodiment of the present application;

[0037] FIG6 is a simulated admittance curve of an ultra-high frequency, wide bandwidth acoustic wave resonator operating at 10 GHz, in which a shear piezoelectric coefficient and a longitudinal piezoelectric coefficient act together, provided in an embodiment of the present application, when the ratio of the periodic wavelength of the interdigital electrode to the thickness of the piezoelectric layer is 1.25 and the Euler angle is -50°;

[0038] FIG7 is a simulated admittance curve of an ultra-high frequency, wide bandwidth acoustic wave resonator operating at 10 GHz, in which a shear piezoelectric coefficient and a longitudinal piezoelectric coefficient act together, when the ratio of the periodic wavelength of the interdigital electrode to the thickness of the piezoelectric layer is 1.25 and the Euler angle is -45°, provided in an embodiment of the present application;

[0039] FIG. 8 is a simulation admittance curve diagram of an ultrahigh frequency large bandwidth acoustic wave resonator with a shear piezoelectric coefficient and a longitudinal piezoelectric coefficient acting together at 30 GHz, according to an embodiment of the present application, when the ratio of the interdigital electrode periodic wavelength to the piezoelectric layer thickness is 0.35 and the Euler angle is -55°. DETAILED DESCRIPTION

[0040] The embodiments in the present application will be described below in detail with reference to the drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort belong to the scope of protection of the present application.

[0041] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0042] Referring to FIGS. 1-3, FIG. 1 is a top view of an acoustic wave resonator according to an embodiment of the present application, FIG. 2 is a sectional view of the acoustic wave resonator shown in FIG. 1, and FIG. 3 is a three-dimensional schematic diagram of Euler angle a rotation of an acoustic wave resonator according to an embodiment of the present application. FIG. 2 is a sectional view of FIG. 1 along the straight dotted line.

[0043] As shown in FIGS. 1 and 2, the acoustic wave resonator comprises:

[0044] a substrate 1, the substrate 1 having a first surface (the upper surface of the substrate 1 in FIG. 2) and a second surface (the lower surface of the substrate 1 in FIG. 2) arranged opposite to each other;

[0045] a piezoelectric layer 2, the piezoelectric layer 2 being arranged on the first surface; the piezoelectric layer 2 comprising a first lithium niobate layer, the piezoelectric layer 2 having a first crystal axis direction X, a second crystal axis direction Y and a third crystal axis direction Z perpendicular to each other; the cutting direction of the first lithium niobate layer being perpendicular to the first crystal axis direction X, and a YZ plane being arranged opposite to the first surface; a three-dimensional crystal rectangular coordinate system XYZ formed by the first lithium niobate layer, the crystal axis directions representing the positive directions of the corresponding coordinate axes;

[0046] an interdigital electrode 30, the interdigital electrode 30 being arranged on the side surface of the piezoelectric layer 2 away from the substrate 1; the interdigital electrode 30 having a plurality of strip electrodes 3 arranged in sequence; the strip electrodes 3 extending along a first direction z; a second direction y being perpendicular to the first direction z and parallel to the YZ plane; it is known that the first direction z is also parallel to the YZ plane;

[0047] The tangential direction of the first lithium niobate layer is perpendicular to the first crystal axis X, that is, the first lithium niobate layer is X-cut lithium niobate. The X-cut lithium niobate has three crystal axes, which are perpendicular to each other, and the three crystal axes form a three-dimensional crystal orthogonal coordinate system XYZ.

[0048] In combination with the coordinate system shown in FIGS. 1-3, the second direction y and the second crystal axis Y have an Euler angle of -90° to -20°, and the ratio of the periodicity wavelength of the interdigital electrode to the thickness of the piezoelectric layer 2 is not less than 0.2 and not greater than 4, so that the electric field formed by the interdigital electrode 30 can excite the piezoelectric layer 2 to form a coupled acoustic wave mode acted on by at least two piezoelectric coefficients, including at least one longitudinal piezoelectric coefficient and at least one shear piezoelectric coefficient. Let the Euler angle be a, and the value of a satisfies: -90°≤a≤-20° (1)

[0049] In the above formula (1), the Euler angle a is negative, indicating that the second direction y is counterclockwise rotated in the YZ plane relative to the second crystal axis Y within an angle range of -90° to -20°.

[0050] Let the periodicity wavelength of the interdigital electrode be λ, and the thickness of the piezoelectric layer 2 be h, then the ratio of the two satisfies:

[0051] In the interdigital electrode 30, adjacent two strip electrodes 3 input different voltages, so that the adjacent strip electrodes 3 form an electric field having a first component (horizontal direction in FIG. 2) and a second direction component (vertical direction in FIG. 2). The first component is parallel to the first surface, and the second component is parallel to the first crystal axis X.

[0052] In the acoustic wave resonator provided by the embodiments of the present application, the above formula (1) and the above formula (2) are simultaneously satisfied, so that the electric field formed by the interdigital electrode 30 can excite the piezoelectric layer 2 to form a coupled acoustic wave mode acted on by at least two piezoelectric coefficients, including at least one longitudinal piezoelectric coefficient and at least one shear piezoelectric coefficient, thereby enabling the resonator to operate at a frequency of 3 GHz to 30 GHz or above, and enabling the electromechanical coupling coefficient to be greater than 6%, thereby improving the performance of the acoustic wave resonator operating in the millimeter wave frequency band.

[0053] In the above formula (3), let the electromechanical coupling coefficient be k 2 , then k 2 satisfies: k 2 ≥6% (3)

[0054] The piezoelectric material has a piezoelectric coefficient matrix e formed by 18 piezoelectric coefficients, which satisfies:

[0055] In the above formula (4), each element in the piezoelectric coefficient matrix represents a piezoelectric coefficient, and the 18 elements in the piezoelectric coefficient matrix are arranged in 3x6. In the piezoelectric material, the piezoelectric coefficient matrix e shown in the above formula (4) is provided, and the values of the elements are different in different piezoelectric materials. Among them, the first three columns of elements in the piezoelectric coefficient matrix e are longitudinal piezoelectric coefficients, and the last three columns of elements are shear piezoelectric coefficients.

[0056] In the embodiments of the present application, since the acoustic wave resonator satisfies the above formula (1) and the above formula (2), the electric field formed by the interdigital electrode 30 can excite at least two piezoelectric coefficients in the piezoelectric material to jointly form the above-mentioned coupled acoustic wave mode.

[0057] If the piezoelectric layer 2 is a single layer of piezoelectric material, at least two piezoelectric coefficients in the piezoelectric material jointly form the above-mentioned coupled acoustic wave mode.

[0058] If the piezoelectric layer 2 includes a plurality of layers of piezoelectric materials stacked in sequence, at least two piezoelectric coefficients in each layer of piezoelectric material jointly form the above-mentioned coupled acoustic wave mode.

[0059] As shown in FIG. 1, the interdigital electrode 30 includes a first electrode group 31 and a second electrode group 32, and the first electrode group 31 and the second electrode group 32 each include a plurality of strip-shaped electrodes 3. The strip-shaped electrodes 3 in the first electrode group 31 and the strip-shaped electrodes 3 in the second electrode group 32 are alternately arranged in the second direction y, thereby forming the interdigital electrode 30 with the structure shown in FIG. 1. The plurality of strip-shaped electrodes 3 in the first electrode group 31 can simultaneously input the same voltage, the plurality of strip-shaped electrodes 3 in the second electrode group 32 can simultaneously input the same voltage, and the strip-shaped electrodes 3 in the first electrode group 31 and the strip-shaped electrodes 3 in the second electrode group 32 input different voltages. In this way, an electric field with a first component and a second direction component can be formed between two adjacent strip-shaped electrodes 3.

[0060] In the acoustic wave resonator provided in the embodiments of the present application, the ratio of the Euler angle a and / or the periodic wavelength λ of the interdigital electrode to the thickness h of the piezoelectric layer 2 can be adjusted to realize the adjustment of the working frequency and the electromechanical coupling coefficient k 2 of the acoustic wave resonator, thereby meeting the high frequency and large bandwidth requirements of the filter in the millimeter wave communication frequency band.

[0061] Optionally, the first surface can be provided with a functional structure for adjusting the resonance performance of the acoustic wave in the piezoelectric layer 2. By providing the functional structure on the surface of the substrate 1, the resonance performance of the acoustic wave in the piezoelectric layer 2 can be adjusted. Based on the adjustment of the shape and structure size of the functional structure, the working frequency and the electromechanical coupling coefficient k 2 of the acoustic wave resonator can be optimized and designed.

[0062] The functional structure can include a cavity arranged in the first surface, and the piezoelectric layer 2 is fixed on the first surface around the cavity opening.

[0063] Alternatively, the functional structure can include a three-dimensional micro-pattern structure in the first surface, which can be a micro-rectangular groove, or a micro-blind hole, or an inverted trapezoidal groove, etc. The piezoelectric layer 2 is fixed on the first surface with the three-dimensional micro-pattern structure.

[0064] The functional structure of the surface of the substrate 1 can adjust the transmission path and the reflection times of the acoustic wave in the piezoelectric layer 2, so as to adjust the resonance performance of the acoustic wave in the piezoelectric layer 2, and thus the working frequency and the electromechanical coupling coefficient k 2 of the acoustic wave resonator can be adjusted through the functional structure.

[0065] In the embodiments of the present application, the thickness h of the piezoelectric layer 2 can be set to a range of 10 nm to 5000 nm. When the Euler angle a is in the range of -90° to -20°, the thickness h of the piezoelectric layer 2 is set to a range of 10 nm to 5000 nm, and the thickness h of the piezoelectric layer 2 is set to a value based on the ratio of the periodic wavelength λ of the interdigital electrode to the thickness h of the piezoelectric layer 2 satisfying the above formula (2), so that the working frequency of the resonator is 3 GHz to 30 GHz or more than 30 GHz, and the electromechanical coupling coefficient k 2 is greater than 6%.

[0066] In one embodiment, the piezoelectric layer 2 can be set as a single-layer first lithium niobate layer, i.e., the piezoelectric layer 2 is a single-layer X-cut lithium niobate, the Euler angle a is -50°, the periodic wavelength λ of the interdigital electrode is 500 nm, the thickness h of the piezoelectric layer 2 is 400 nm, and the ratio of the periodic wavelength λ of the interdigital electrode to the thickness h of the piezoelectric layer is 1.25. In this embodiment, the working frequency can be 10 GHz, and the electromechanical coupling coefficient k 2 is 28% of an ultrahigh frequency large bandwidth acoustic wave resonator.

[0067] In another embodiment, the piezoelectric layer 2 can also be set as a single-layer first lithium niobate layer, the Euler angle a is -45°, the periodic wavelength λ of the interdigital electrode is 500 nm, the thickness h of the piezoelectric layer 2 is 400 nm, and the ratio of the periodic wavelength λ of the interdigital electrode to the thickness h of the piezoelectric layer is 1.25. In this embodiment, the working frequency can be 10 GHz, and the electromechanical coupling coefficient k 2 is 26.4% of an ultrahigh frequency large bandwidth acoustic wave resonator.

[0068] In another embodiment, the piezoelectric layer 2 is also a single layer of the first lithium niobate layer, the Euler angle a is -55°, the interdigital electrode periodic wavelength λ is 140 nm, the thickness h of the piezoelectric layer 2 is 400 nm, and the ratio of the interdigital electrode periodic wavelength λ to the thickness h of the piezoelectric layer is 0.35. In this embodiment, the working frequency of the ultrahigh frequency large-bandwidth acoustic wave resonator can be 30 GHz, and the electromechanical coupling coefficient k 2 is 11.7%.

[0069] In the embodiments of the present application, at least one resonance auxiliary layer is arranged between the first lithium niobate layer and the substrate 1, and / or at least one resonance auxiliary layer is arranged between the first lithium niobate layer and the interdigital electrode 30, and the resonance auxiliary layer is used to adjust the resonance performance of the acoustic wave in the piezoelectric layer 2.

[0070] By increasing the auxiliary resonance layer, the resonance performance of the acoustic wave in the piezoelectric layer 2 can be adjusted, and thus the resonance performance of the acoustic wave resonator can be adjusted. The auxiliary resonance layer and the first lithium niobate layer are sequentially stacked in the thickness direction of the piezoelectric layer 2.

[0071] Optionally, the resonance auxiliary layer is any one of a second lithium niobate layer, a lithium tantalate layer, an aluminum nitride layer, a scandium-doped aluminum nitride layer, and a zinc oxide layer; and the second lithium niobate layer has a different cut direction from the first lithium niobate layer. By adjusting any one of the design parameters of the material, the number of layers, the thickness, and the position of the auxiliary layer relative to the first lithium niobate layer, the resonance performance of the acoustic wave resonator can be optimized, and thus the working frequency and the electromechanical coupling coefficient k 2 of the acoustic wave resonator can be optimized.

[0072] In the embodiments of the present application, the material of the interdigital electrode 30 is one or an alloy formed by multiple of tungsten, platinum, gold, silver, copper, aluminum, molybdenum, chromium, nickel, and titanium. The interdigital electrode 30 made of the above-mentioned materials can better adapt to the piezoelectric material, has good compatibility with the piezoelectric material, and has good electrical conductivity, which can effectively improve the electromechanical coupling coefficient k 2 .

[0073] In the embodiments of the present application, the substrate 1 is any one of a silicon carbide (SiC) substrate, a sapphire (Al2O3) substrate, a gallium nitride (GaN) substrate, and a silicon (Si) substrate. The substrate 1 made of the above-mentioned materials has good acoustic wave reflection capability, based on which the acoustic wave can be better confined in the piezoelectric layer 2 to prevent acoustic wave leakage and thus reduce energy loss; has good mechanical support performance to ensure that the acoustic wave generated by the piezoelectric layer 2 can propagate along the second direction y when the interdigital electrode 30 applies voltage; has good electromagnetic compatibility with the piezoelectric material, which can effectively improve the electromechanical coupling coefficient k 2 ; has good thermal stability, which can better reduce the influence of temperature on the performance of the acoustic wave resonator.

[0074] Optionally, the number of the strip electrodes 3 in the interdigital electrode 30 is 2-500; the thickness of the strip electrode 3 is 5 nm-500 nm; the width of the strip electrode 3 is 0.001 μm-5 μm; and the length of the strip electrode 3 is 1-500 μm. The strip electrode 3 with the design parameters provided in the embodiment can better excite the piezoelectric layer 2 to form a coupled acoustic wave mode acted by at least two piezoelectric coefficients.

[0075] As shown in FIG. 4, FIG. 4 is a sectional view of an ultrahigh frequency large bandwidth acoustic resonator with a ratio of the interdigital electrode periodic wavelength to the piezoelectric layer thickness of 1.25 according to an embodiment of the present application. The electric field between the two adjacent strip electrodes 3 can excite an acoustic wave with an interdigital electrode periodic wavelength of λ.

[0076] The interdigital electrode 30 has a plurality of strip electrodes 3 arranged in the second direction y in sequence, and the repeat period dimension of the strip electrode satisfies the same condition as the interdigital electrode periodic wavelength λ. That is, in the second direction y, the piezoelectric layer 2 is sequentially divided into a plurality of regions, each region is provided with two adjacent strip electrodes 2, and the width of a region in the second direction y satisfies the same condition as the repeat period dimension. The repeat period dimension is determined, and the interdigital electrode periodic wavelength λ that can be excited is determined. The two parameters satisfying the same condition means that the two parameters are the same or approximately the same.

[0077] As shown in FIG. 5, FIG. 5 is a schematic diagram of the sectional polarized displacement of an ultrahigh frequency large bandwidth acoustic resonator with a ratio of the interdigital electrode periodic wavelength to the piezoelectric layer thickness of 1.25, in which a shear piezoelectric coefficient and a longitudinal piezoelectric coefficient jointly act according to an embodiment of the present application. In FIG. 5, the direction of the polarized displacement is indicated by a one-way arrow. The shear piezoelectric coefficient makes the polarized displacement direction of the acoustic wave be the thickness direction of the piezoelectric layer 2, and the longitudinal piezoelectric coefficient makes the polarized displacement direction of the acoustic wave be the first component direction of the electric field. As can be seen from FIG. 5, a coupled acoustic wave mode acted by at least two piezoelectric coefficients can be formed in the acoustic resonator.

[0078] As shown in FIG. 6, FIG. 6 is a simulation admittance curve of an ultrahigh frequency large bandwidth acoustic resonator with a ratio of the interdigital electrode periodic wavelength to the piezoelectric layer thickness of 1.25 and Euler angles of -50°, in which a shear piezoelectric coefficient and a longitudinal piezoelectric coefficient jointly act according to an embodiment of the present application. As can be seen from the curve shown in FIG. 6, the corresponding electromechanical coupling coefficient k 2 is 28%. The calculation formula of the electromechanical coupling coefficient k 2 is as follows:

[0079] In the above formula (5), f s is the series resonance frequency of the acoustic resonator, and fp is a parallel resonant frequency of the acoustic wave resonator.

[0080] As shown in FIG. 7, FIG. 7 is a simulation admittance curve diagram of an ultrahigh-frequency large-bandwidth acoustic wave resonator with a ratio of a periodic interdigital electrode wavelength to a piezoelectric layer thickness of 1.25 and Euler angles of -45°, in which one shear piezoelectric coefficient and one longitudinal piezoelectric coefficient jointly act at 10 GHz. Based on the curve shown in FIG. 7, the corresponding electromechanical coupling coefficient k 2 is 26.4% according to the calculation of the above formula (5).

[0081] The simulation setting conditions of the simulation admittance curves shown in FIG. 6 and FIG. 7 are the same except that the Euler angles a are different. It can be found by comparing the two simulation results that, although the admittance curve when the Euler angles a is -45° is smoother than the admittance curve when the Euler angles a is -50°, that is, the relative number of spurious modes is relatively small, but it is at the cost of the reduction of the electromechanical coupling coefficient k 2 from 28% to 26.4%. Therefore, in a specific application scenario, the ratio of the periodic interdigital electrode wavelength λ to the thickness h of the piezoelectric layer 2 and the Euler angles a can be comprehensively considered and weighed according to actual needs.

[0082] As shown in FIG. 8, FIG. 8 is a simulation admittance curve diagram of an ultrahigh-frequency large-bandwidth acoustic wave resonator with a ratio of a periodic interdigital electrode wavelength to a piezoelectric layer thickness of 0.35 and Euler angles of -55°, in which one shear piezoelectric coefficient and one longitudinal piezoelectric coefficient jointly act at 30 GHz. Based on the curve shown in FIG. 8, the corresponding electromechanical coupling coefficient k 2 is 11.7% according to the calculation of the above formula (5).

[0083] It can be known from the above description that, when -90°≤a≤-20° is set and , the working frequency of the acoustic wave resonator can be 3 GHz-30 GHz or more than 30 GHz, and the electromechanical coupling coefficient k 2 can be greater than 6%. Moreover, when varies in the above range and a is adjusted in the YZ plane rotation in the above range, the working frequency and the electromechanical coupling coefficient k 2 of the acoustic wave resonator can be optimized and adjusted. Therefore, the acoustic wave resonator is an ultrahigh-frequency large-bandwidth acoustic wave resonator, the working frequency range of which covers many frequency bands of millimeter wave communication applications, and can be well applied to the millimeter wave communication field to meet the high use demand of high frequency and wide bandwidth in the millimeter wave communication field.

[0084] Based on the acoustic resonator provided in the above embodiments, another embodiment of the present application further provides an electronic device, which comprises the acoustic resonator provided in any one of the above embodiments. The electronic device can be any one of a wireless communication device, a display device, a satellite positioning device, and a micro-electromechanical device.

[0085] If the electronic device is a wireless communication device, the acoustic resonator can be used to filter unnecessary signals and noises, thereby improving reception quality. If the electronic device is a display device, the acoustic resonator can be used to process signals, thereby improving image and sound quality. If the electronic device is a satellite positioning device, the acoustic resonator can be used to improve positioning accuracy and reliability. If the electronic device is a micro-electromechanical device, the acoustic resonator is used to convert electrical energy into mechanical acoustic energy, thereby generating reliable oscillation for high-frequency clock output.

[0086] In the description of the present application, each embodiment is described in a progressive, or parallel, or a combination of progressive and parallel manner, and each embodiment focuses on the difference from other embodiments. The same or similar parts of each embodiment can be referred to each other. The embodiments provided by the embodiments of the present application can be combined with each other without contradiction.

[0087] It should be noted that in the description of the present application, it should be understood that the drawings and the description of the embodiments are illustrative rather than limiting. The same reference numerals in the embodiments throughout the specification indicate the same structure. In addition, for the purpose of understanding and ease of description, the thickness of some layers, films, panels, regions, etc. may be exaggerated in the drawings. It can be understood that when an element such as a layer, film, region or substrate is referred to as "on" another element, the element can be directly on the other element or there can be an intervening element. In addition, "on" means positioning an element on another element or below another element, but not essentially positioning on the upper side of another element according to the direction of gravity.

[0088] The terms "upper", "lower", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. When a component is considered to be "connected" to another component, it can be directly connected to the other component or there can be a component disposed therebetween.

[0089] It is also noted that the relational terms herein, such as first and second, and the like, are used solely to distinguish one from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a vesicle or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such vesicle or apparatus. An element proceeded by "comprises a... " does not, without more constraints, preclude the existence of additional identical elements in the vesicle or apparatus that comprises the recited element.

[0090] The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An acoustic wave resonator, characterized in that include: A substrate having a first surface and a second surface opposite to each other; a piezoelectric layer disposed on the first surface; the piezoelectric layer comprising a first lithium niobate layer, the piezoelectric layer having a first crystal axis X, a second crystal axis Y, and a third crystal axis Z that are perpendicular to each other; a tangential direction of the first lithium niobate layer being perpendicular to the first crystal axis X; and a YZ plane being disposed opposite the first surface; An interdigitated electrode is provided on a surface of the piezoelectric layer facing away from the substrate; the interdigitated electrode comprises a plurality of strip electrodes arranged in sequence; the strip electrodes extend along a first direction; a second direction is perpendicular to the first direction and parallel to the YZ plane; In which, there is an Euler angle of -90° to -20° between the second direction and the second crystal axis Y, and the ratio of the periodic wavelength of the interdigital electrodes of the acoustic wave resonator to the thickness of the piezoelectric layer is not less than 0.2 and not greater than 4, so that the electric field formed by the interdigital electrodes can excite the piezoelectric layer to form a coupled acoustic wave mode acted upon by at least two piezoelectric coefficients, and the at least two piezoelectric coefficients include: at least one longitudinal piezoelectric coefficient and at least one shear piezoelectric coefficient.

2. The acoustic wave resonator according to claim 1, characterized in that The first surface has a functional structure for adjusting the resonance performance of the acoustic wave in the piezoelectric layer.

3. The acoustic wave resonator according to claim 1, wherein The thickness of the piezoelectric layer ranges from 10 nm to 5000 nm.

4. The acoustic wave resonator according to claim 1, wherein The piezoelectric layer is a single-layer lithium niobate layer, the Euler angle is -50°, the periodic wavelength of the interdigitated electrode is 500 nm, the thickness of the piezoelectric layer is 400 nm, and the ratio is 1.25; Or, the piezoelectric layer is a single-layered first lithium niobate layer, the Euler angle is -45°, the periodic wavelength of the interdigitated electrode is 500 nm, the thickness of the piezoelectric layer is 400 nm, and the ratio is 1.25; Alternatively, the piezoelectric layer is a single-layer first lithium niobate layer, the Euler angle is -55°, the periodic wavelength of the interdigitated electrodes is 140 nm, the thickness of the piezoelectric layer is 400 nm, and the ratio is 0.

35.

5. The acoustic wave resonator according to claim 1, wherein There is at least one resonance auxiliary layer between the first lithium niobate layer and the substrate, and / or there is at least one resonance auxiliary layer between the first lithium niobate layer and the interdigitated electrode, and the resonance auxiliary layer is used to adjust the resonance performance of the sound wave in the piezoelectric layer.

6. The acoustic wave resonator according to claim 5, characterized in that The resonance auxiliary layer is any one of a second lithium niobate layer, a lithium tantalate layer, an aluminum nitride layer, a scandium-doped aluminum nitride layer, and a zinc oxide layer; The second lithium niobate layer and the first lithium niobate layer have different tangent directions.

7. The acoustic wave resonator according to claim 1, characterized in that The material of the interdigital electrodes is one of tungsten, platinum, gold, silver, copper, aluminum, molybdenum, chromium, nickel and titanium, or an alloy formed by multiple thereof.

8. The acoustic wave resonator according to claim 1, wherein The substrate is any one of a silicon carbide substrate, a sapphire substrate, a gallium nitride substrate and a silicon substrate.

9. The acoustic wave resonator according to claim 1, characterized in that The number of strip electrodes in the interdigitated electrodes is 2 to 500; The thickness of the strip electrode is 5nm to 500nm; The width of the strip electrodes is 0.001 μm to 5 μm; The length of the strip electrodes is 1-500 μm.

10. An electronic device, characterized in that: include: The acoustic wave resonator according to any one of claims 1 to 9.

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