Acoustic wave resonator, method for preparing acoustic wave resonator, and electronic device

Abstract

The present application discloses an acoustic wave resonator, a method for preparing an acoustic wave resonator, and an electronic device. The acoustic wave resonator includes: a substrate, a piezoelectric layer, and at least two interdigital electrodes; the piezoelectric layer is arranged on the surface of the substrate, and a plurality of grooves are arranged on the side where the piezoelectric layer contacts the substrate or on the side away from the substrate, the depths of the plurality of grooves are all less than the thickness of the piezoelectric layer, the number of the grooves is the same as the number of the interdigital electrodes, and a interdigital electrode is arranged in each of the plurality of grooves. In this way, the interdigital electrodes penetrate deeper into the interior of the piezoelectric layer, so that the vibration mode of the excited acoustic wave can be closer to the body wave, that is, propagating inside the entire medium. Therefore, in the process of increasing the frequency, there is no need to change the size of the interdigital electrodes, so that the resistance of the interdigital electrodes is not increased, thereby avoiding the reduction of the quality factor of the acoustic wave resonator and realizing a high-quality acoustic wave resonator.

Description

Technical Field

[0001] The present application relates to the technical field of resonators, and in particular to an acoustic wave resonator, a method for preparing an acoustic wave resonator, and an electronic device. Background Art

[0002] At present, acoustic wave resonators are widely used in the communications industry due to their small size, large bandwidth and high quality factor (Q value). However, with the development of communication technology, the frequency bands currently used are becoming more and more crowded, and it is necessary to further explore higher frequency wireless communication technologies. Therefore, research on higher frequency acoustic wave resonators is also crucial.

[0003] Taking the interdigital acoustic wave resonator as an example, in actual applications, as the frequency of the interdigital acoustic wave resonator continues to increase, the interdigital electrodes will shrink accordingly, causing the resistance of the interdigital electrodes to increase. The larger resistance will seriously reduce the quality factor, resulting in a decrease in the quality of the acoustic wave resonator. Summary of the invention

[0004] The embodiments of the present application provide an acoustic wave resonator, a method for preparing the acoustic wave resonator, and an electronic device, so as to avoid a decrease in the quality factor during the process of increasing the frequency of the interdigital acoustic wave resonator.

[0005] In a first aspect, an embodiment of the present application provides an acoustic wave resonator, comprising: a substrate, a piezoelectric layer, and at least two interdigital electrodes;

[0006] The piezoelectric layer is arranged on the surface of the substrate, and a plurality of grooves are arranged on the side where the piezoelectric layer contacts the substrate or on the side away from the substrate. The depths of the plurality of grooves are all less than the thickness of the piezoelectric layer. The number of the grooves is the same as the number of the interdigitated electrodes, and an interdigitated electrode is arranged in each of the plurality of grooves.

[0007] Optionally, a ratio of a depth of each of the plurality of grooves to a thickness of each interdigital electrode is 1:1, 2:1, 3:1 or 9:8.

[0008] Optionally, when the ratio of the depth of each groove to the thickness of each interdigital electrode is 1:1, the acoustic wave resonator is configured to operate at a frequency of 5.3 GHz;

[0009] When the ratio of the depth of each groove to the thickness of each interdigital electrode is 2:1, the acoustic wave resonator is configured to operate at a frequency of 6.6 GHz;

[0010] When the ratio of the depth of each groove to the thickness of each interdigital electrode is 3:1, the acoustic wave resonator is used to operate at a frequency of 8.3 GHz;

[0011] When the ratio of the depth of each groove to the thickness of each interdigital electrode is 9:8, the acoustic wave resonator is configured to operate at a frequency of 14.5 GHz.

[0012] Optionally, the depth of each groove is 10 nanometers to 10,000 nanometers, the thickness of each interdigitated electrode is 10 nanometers to 10,500 nanometers, and the thickness of the piezoelectric layer is 10 nanometers to 10,000 nanometers.

[0013] Optionally, in the case where a plurality of grooves are provided on a side of the piezoelectric layer facing away from the substrate, a silicon dioxide layer is covered on a side of the at least two interdigitated electrodes facing away from the substrate, and a thickness of the silicon dioxide layer is 1 to 300 nanometers.

[0014] Optionally, the piezoelectric layer is a lithium niobate layer, and the Euler angle of the lithium niobate layer is -90° to 90°.

[0015] Optionally, each interdigital electrode has an electrical conductivity greater than 5×10 6 Siemens per meter of metal.

[0016] Optionally, the substrate includes at least one of silicon, aluminum oxide, silicon oxide, glass, aluminum nitride, scandium aluminum nitride, quartz or silicon carbide.

[0017] In a second aspect, an embodiment of the present application provides a method for preparing an acoustic wave resonator, comprising:

[0018] providing a substrate;

[0019] forming a piezoelectric layer on a surface of the substrate;

[0020] Etching a plurality of grooves on a side of the piezoelectric layer contacting the substrate or on a side away from the substrate, wherein the depths of the plurality of grooves are all less than the thickness of the piezoelectric layer;

[0021] An interdigital electrode is formed in each of the plurality of grooves.

[0022] In a third aspect, an embodiment of the present application provides an electronic device, comprising any implementation of the above-mentioned acoustic wave resonator.

[0023] It can be seen from the above technical solutions that the embodiments of the present application have the following advantages:

[0024] In an embodiment of the present application, an acoustic wave resonator including a substrate, a piezoelectric layer and at least two interdigitated electrodes may be provided. The piezoelectric layer is arranged on the surface of the substrate, and a plurality of grooves are arranged on the side where the piezoelectric layer contacts the substrate or on the side away from the substrate, the depths of the plurality of grooves are all less than the thickness of the piezoelectric layer, the number of the grooves is the same as the number of the interdigitated electrodes, and a interdigitated electrode is arranged in each of the plurality of grooves. In this way, the interdigitated electrodes can penetrate deeper into the interior of the piezoelectric layer by being embedded in the grooves of the piezoelectric layer, so that the vibration mode of the excited acoustic wave can be closer to the body wave, that is, propagated throughout the medium. Therefore, even in the process of increasing the frequency, there is no need to change the size of the interdigitated electrodes, so that the resistance of the interdigitated electrodes is not increased, thereby avoiding the reduction of the quality factor of the acoustic wave resonator and realizing a high-quality acoustic wave resonator. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic cross-sectional view of an acoustic wave resonator provided in an embodiment of the present application;

[0026] Figure 2 A schematic cross-sectional view of another acoustic wave resonator provided in an embodiment of the present application;

[0027] Figure 3 A schematic cross-sectional view of another acoustic wave resonator provided in an embodiment of the present application;

[0028] Figure 4 A schematic cross-sectional view of another acoustic wave resonator provided in an embodiment of the present application;

[0029] Figure 5 A schematic diagram of Euler angle rotation provided in an embodiment of the present application;

[0030] Figure 6 A schematic cross-sectional view of an acoustic wave resonator for operating at a frequency of 5.3 GHz provided in an embodiment of the present application;

[0031] Figure 7 A simulated admittance curve of an acoustic wave resonator operating at a frequency of 5.3 GHz provided in an embodiment of the present application;

[0032] Figure 8 A schematic cross-sectional view of an acoustic wave resonator for operating at a frequency of 6.6 GHz provided in an embodiment of the present application;

[0033] Fig. 9 A simulated admittance curve of an acoustic wave resonator operating at a frequency of 6.6 GHz provided in an embodiment of the present application;

[0034] Fig.10A schematic cross-sectional view of an acoustic wave resonator for operating at a frequency of 8.3 GHz provided in an embodiment of the present application;

[0035] Fig.11 A simulated admittance curve of an acoustic wave resonator operating at a frequency of 8.3 GHz provided in an embodiment of the present application;

[0036] Fig.12 A simulated admittance curve of an acoustic wave resonator operating at a frequency of 14.5 GHz provided in an embodiment of the present application;

[0037] Fig.13 A schematic cross-sectional view of an acoustic wave resonator provided in an embodiment of the present application, wherein a silicon dioxide layer is covered on a side of at least two interdigitated electrodes facing away from a substrate;

[0038] Fig.14 A schematic cross-sectional view of another acoustic wave resonator provided in an embodiment of the present application, wherein a silicon dioxide layer is covered on a side of at least two interdigitated electrodes facing away from a substrate;

[0039] Fig.15 A schematic cross-sectional view of another acoustic wave resonator provided in an embodiment of the present application, wherein a silicon dioxide layer is covered on a side of at least two interdigitated electrodes facing away from a substrate;

[0040] Fig.16 A top view of the internal structure of an acoustic wave resonator provided in the present application;

[0041] Fig.17 A flow chart of a method for preparing an acoustic wave resonator provided in an embodiment of the present application. DETAILED DESCRIPTION

[0042] As mentioned above, with the continuous development of communication technology, the functions of communication systems are becoming increasingly complex. Especially with the rise of the fifth generation of mobile communication technology, communication systems not only need to support multiple modes such as Global System for Mobile Communications (GSM), Wideband Code Division Multiple Access (WCDMA), Long Term Evolution (LTE), New Radio (NR), Wi-Fi and Bluetooth, but also need to cover multiple frequency bands. In order to effectively suppress the mutual interference between adjacent frequency bands, the communication system needs to have high isolation characteristics. In addition, compared with LTE, the uplink and downlink throughput of the NR mode has been greatly improved, which requires the RF front-end system to have ultra-low signal delay, ultra-large data transmission, and ultra-low bit error rate performance. In addition, the bandwidth of the NR band is much higher than that of LTE. For example, the relative bandwidth of the n77 band is as high as 24%. Therefore, the RF front-end filter needs to have indicators such as low insertion loss, high out-of-band suppression, high rectangularity, high roll-off and large bandwidth to meet the high performance requirements of the 5G NR system.

[0043] Based on the above requirements, since the quality factor of the acoustic wave resonator is closely related to the low loss and high suppression of the filter, the low phase noise of the oscillator and the high sensitivity of the sensor, it is very important to design an acoustic wave resonator with a higher quality factor.

[0044] In the process of increasing the frequency of the traditional interdigital acoustic wave resonator, the interdigital electrodes will shrink, which will increase the resistance of the interdigital electrodes. The larger resistance will seriously deteriorate the quality factor, resulting in a decrease in the quality of the acoustic wave resonator. Therefore, how to improve the quality factor of the acoustic wave resonator in the process of increasing the frequency is an urgent problem that technicians in this field need to solve.

[0045] Based on this, in order to solve the above problems, an embodiment of the present application provides an acoustic wave resonator, which may include a substrate, a piezoelectric layer and at least two interdigital electrodes. Among them, the piezoelectric layer is arranged on the surface of the substrate, and a plurality of grooves are arranged on the side where the piezoelectric layer contacts the substrate or on the side away from the substrate, the depths of the plurality of grooves are all less than the thickness of the piezoelectric layer, the number of the grooves is the same as the number of the interdigital electrodes, and an interdigital electrode is arranged in each of the plurality of grooves.

[0046] In this way, the interdigitated electrodes can be embedded in the grooves of the piezoelectric layer and can go deeper into the interior of the piezoelectric layer, so that the vibration mode of the excited sound wave can be closer to the body wave, that is, propagating inside the entire medium. Therefore, even in the process of increasing the frequency, there is no need to change the size of the interdigitated electrodes, so that the resistance of the interdigitated electrodes is not increased, thereby avoiding the reduction of the quality factor of the acoustic wave resonator and realizing a high-quality acoustic wave resonator. In addition, since the interdigitated electrodes are arranged in the grooves of the piezoelectric layer, the interdigitated electrodes are closer to the center of the piezoelectric layer, and the thickness of the interdigitated electrodes can be increased in the grooves to increase the cross-section of the interdigitated electrodes, thereby reducing the resistance of the interdigitated electrodes and further improving the quality factor of the acoustic wave resonator.

[0047] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0048] Figure 1 A schematic cross-sectional view of an acoustic wave resonator provided in an embodiment of the present application; Figure 2 A schematic cross-sectional view of another acoustic wave resonator provided in an embodiment of the present application; Figure 3 A schematic cross-sectional view of another acoustic wave resonator provided in an embodiment of the present application; Figure 4 A cross-sectional schematic diagram of another acoustic wave resonator provided in an embodiment of the present application. Figures 1 to 4 As shown, the acoustic wave resonator provided in the embodiment of the present application may include: a substrate 1, a piezoelectric layer 2 and at least two interdigital electrodes 3.

[0049] Among them, the piezoelectric layer 2 is arranged on the surface of the substrate 1, and a plurality of grooves are arranged on the side where the piezoelectric layer 2 contacts the substrate 1 or on the side away from the substrate 1. The depths of the plurality of grooves are all less than the thickness of the piezoelectric layer 2. The number of grooves is the same as the number of interdigitated electrodes 3. A interdigitated electrode 3 is arranged in each of the plurality of grooves.

[0050] Optionally, in the embodiment of the present application, the substrate 1 may include at least one of silicon, aluminum oxide, silicon oxide, glass, aluminum nitride, scandium aluminum nitride, quartz or silicon carbide.

[0051] The number of the plurality of grooves may be 2 to 500, for example, the number of the plurality of grooves may be 2, 100, 200, 250, 380 or 500. The depth of each groove may be 10 nanometers to 10000 nanometers, for example, the depth of each groove may be 10 nanometers, 100 nanometers, 2900 nanometers, 5000 nanometers, 8900 nanometers or 10000 nanometers, etc. The width of each groove may be 0.001 micrometer to 5 micrometers, for example, the width of each groove may be 0.001 micrometer, 1 micrometer, 2.6 micrometers, 4.1 micrometers or 5 micrometers. The length of each groove may be 1 micrometer to 500 micrometers, for example, the length of each groove may be 1 micrometer, 80 micrometers, 250 micrometers, 360 micrometers, 499 micrometers or 500 micrometers.

[0052] The interdigital electrode 3 may have a conductivity greater than 5×10 6 Siemens per meter of metal. For example, the interdigital electrodes 3 can be gold, silver, copper, aluminum, molybdenum, chromium, nickel, platinum, or an alloy composed of titanium gold, titanium aluminum, chromium gold and chromium aluminum.

[0053] In practical applications, the interdigital electrodes can be arranged in pairs. Accordingly, since the number of grooves is the same as the number of interdigital electrodes 3, the number of interdigital electrodes and the above-mentioned grooves is an even number. Based on this, the number of interdigital electrodes 3 can be 2 to 500, for example, the number of interdigital electrodes 3 can be 2, 100, 200, 250, 380 or 500. The thickness of each interdigital electrode 3 can be 10 nanometers to 10500 nanometers, for example, the thickness of each interdigital electrode 3 can be 10 nanometers, 100 nanometers, 2900 nanometers, 5000 nanometers, 8900 nanometers, 10000 nanometers or 10500 nanometers. The width of each interdigital electrode 3 can be 0.001 micrometer to 10 micrometers, for example, the width of each interdigital electrode 3 can be 0.001 micrometer, 1 micrometer, 2.6 micrometers, 4.1 micrometers, 7 micrometers, 9.6 micrometers or 10 micrometers. The length of each interdigital electrode 3 may be 1 micrometer to 500 micrometers. For example, the length of each interdigital electrode 3 may be 1 micrometer, 80 micrometers, 250 micrometers, 360 micrometers, 499 micrometers or 500 micrometers.

[0054] In addition, since the interdigital electrodes are arranged in the grooves of the piezoelectric layer, the interdigital electrodes are closer to the center of the piezoelectric layer, and the thickness of the interdigital electrodes can be increased in the grooves to increase the cross-section of the interdigital electrodes, thereby reducing the resistance of the interdigital electrodes and further improving the quality factor of the acoustic wave resonator. Based on this, in the embodiment of the present application, the thickness of the interdigital electrodes and the depth of the grooves are adaptively increased within the corresponding value range.

[0055] As an example, combining Figure 1As shown, a plurality of grooves may be provided on the side of the piezoelectric layer 2 facing away from the substrate 1. The plurality of grooves may be etched into a rectangular shape. For each groove, the thickness of the interdigital electrode 3 provided in the groove is less than the depth of the groove.

[0056] As another example, combining Figure 2 As shown, a plurality of grooves may be provided on the side of the piezoelectric layer 2 facing away from the substrate 1. The plurality of grooves may be etched into a rectangular shape. For each groove, the thickness of the interdigital electrode 3 provided in the groove may be greater than the depth of the groove.

[0057] As another example, combining Figure 3 As shown, a plurality of grooves may be provided on the side where the piezoelectric layer 2 contacts the substrate 1. The plurality of grooves may be etched into a rectangular shape. For each groove, the thickness of the interdigital electrode 3 provided in the groove may be equal to the depth of the groove.

[0058] As another example, combining Figure 4 As shown, a plurality of grooves may be provided on the side of the piezoelectric layer 2 facing away from the substrate 1. The plurality of grooves may be etched into a trapezoidal shape. For each groove, the interdigitated electrode 3 in the groove may be arranged in a conformal manner along the shape of the groove and extend out of the groove to cover the upper surface of the piezoelectric layer 2.

[0059] It should be noted that in the embodiment of the present application, the shapes of the grooves and the interdigital electrodes 3 are not specifically limited, and may be, for example, rectangular, trapezoidal, triangular, elliptical or circular, etc. The above is merely an exemplary description through a variety of possible implementations.

[0060] The thickness of the piezoelectric layer 2 is 10 nanometers to 10000 nanometers. For example, the thickness of the piezoelectric layer 2 can be 10 nanometers, 100 nanometers, 2900 nanometers, 5000 nanometers, 8900 nanometers or 10000 nanometers.

[0061] Accordingly, the piezoelectric layer 2 may be a lithium niobate layer. Further, Figure 5 A schematic diagram of Euler angle rotation provided in an embodiment of the present application. Figure 5 As shown, in the embodiment of the present application, the angle formed by the horizontal electric field direction +y' formed by the interdigital electrodes 3 and the y-axis direction in the coordinate system of the piezoelectric layer 2 can be taken as the Euler angle α. Accordingly, the Euler angle α of the lithium niobate layer is -90° to 90°.

[0062] Optionally, in order to further improve the electromechanical coupling coefficient of the acoustic wave resonator, the embodiment of the present application can set the value range of the Euler angle α of the above-mentioned lithium niobate layer to -20°~20° or -80°~40°.

[0063] Further, in the embodiment of the present application, the ratio of the depth of each groove in the plurality of grooves to the thickness of each interdigital electrode 3 is in the range of 0.5 to 10, for example, the ratio of the depth of each groove to the thickness of each interdigital electrode 3 is 1:1, 2:1, 3:1 or 9:8, etc. For ease of understanding, the implementation methods corresponding to the above ratios are exemplarily described below in conjunction with the embodiments and drawings.

[0064] As a possible implementation, Figure 6 A schematic cross-sectional view of an acoustic wave resonator for operating at a frequency of 5.3 GHz provided in an embodiment of the present application. Figure 6 As shown, the depth d of each groove and the thickness t of each interdigital electrode 3 are e When the ratio is 1:1, the depth d of each groove is 90 nanometers, and the thickness of each interdigital electrode 3 is t e is 90 nanometers, and the interdigital electrode 3 in each groove is completely embedded in the groove. A plurality of grooves are arranged on the side where the piezoelectric layer 2 contacts the substrate 1, and the surface of the groove after the interdigital electrode 3 is embedded is in the same plane as the side where the piezoelectric layer 2 contacts the substrate 1. In the case where a plurality of grooves are arranged on the side of the piezoelectric layer 2 facing away from the substrate 1, the surface of the groove after the interdigital electrode 3 is embedded is in the same plane as the side where the piezoelectric layer 2 faces away from the substrate 1. The duty cycle of each interdigital electrode 3 (that is, the ratio of the width and spacing of the electrode fingers included in each interdigital electrode 3) is 50%. The piezoelectric layer 2 can be cut into X-cut lithium niobate, and the Euler angle of the piezoelectric layer 2 is -5°. In addition, the sum of twice the width of the interdigital electrode 3 and twice the spacing between adjacent interdigital electrodes 3 is taken as the horizontal wavelength λ, and the horizontal wavelength λ is 900 nanometers. The horizontal wavelength λ is proportional to the thickness t of the piezoelectric layer 2. LN The ratio is 3: 1. Based on the above design, the acoustic wave resonator can be used to operate at a frequency of 5.3 GHz.

[0065] Figure 7 A simulated admittance curve of an acoustic wave resonator operating at a frequency of 5.3 GHz provided in an embodiment of the present application. Figure 7 As shown in the simulation admittance curve, the horizontal axis represents frequency (Frequency / GHZ) and the vertical axis represents admittance (Admittance / dB). When the acoustic wave resonator operates at a frequency of 5.3 GHz, the electromechanical coupling coefficient is about 40%. The electromechanical coupling coefficient can be calculated by the following formula (1):

[0066] (1)

[0067] Among them, k 2 is the electromechanical coupling coefficient, f s The frequency of the highest admittance point in the true admittance curve, f pThe frequency of the lowest point of admittance in the simulated admittance curve.

[0068] As another possible implementation, Figure 8 A schematic cross-sectional view of an acoustic wave resonator for operating at a frequency of 6.6 GHz provided in an embodiment of the present application. Figure 8 As shown, the depth d of each groove and the thickness t of each interdigital electrode 3 are e When the ratio is 2:1, the depth d of each groove is 180 nanometers, and the thickness of each interdigital electrode 3 is t e The cross-finger electrode 3 in each groove is completely embedded in the groove. The duty cycle of each cross-finger electrode 3 is 50%. The piezoelectric layer 2 can be cut in the direction of X-cut lithium niobate, and the Euler angle of the piezoelectric layer 2 is -5°. In addition, the sum of twice the width of the cross-finger electrode 3 and twice the spacing between adjacent cross-finger electrodes 3 is taken as the horizontal wavelength λ, and the horizontal wavelength λ is 900 nanometers. The horizontal wavelength λ is proportional to the thickness t of the piezoelectric layer 2. LN The ratio is 3: 1. Based on the above design, the acoustic wave resonator can be used to operate at a frequency of 6.6 GHz.

[0069] Fig. 9 A simulated admittance curve of an acoustic wave resonator operating at a frequency of 6.6 GHz provided in an embodiment of the present application. Fig. 9 As shown in the simulation admittance curve, the horizontal axis represents frequency (Frequency / GHZ) and the vertical axis represents admittance (Admittance / dB). When the acoustic wave resonator operates at a frequency of 6.6 GHz, the electromechanical coupling coefficient is greater than 26%. The electromechanical coupling coefficient can be calculated using the above formula (1).

[0070] As another possible implementation, Fig.10 A cross-sectional schematic diagram of an acoustic wave resonator for operating at a frequency of 8.3 GHz provided in an embodiment of the present application. Fig.10 As shown, the depth d of each groove and the thickness t of each interdigital electrode 3 are e When the ratio is 3:1, the depth d of each groove is 270 nanometers, and the thickness of each interdigital electrode 3 is t e The cross-finger electrode 3 in each groove is completely embedded in the groove. The duty cycle of each cross-finger electrode 3 is 50%. The piezoelectric layer 2 can be cut in the direction of X-cut lithium niobate, and the Euler angle of the piezoelectric layer 2 is -5°. In addition, the sum of twice the width of the cross-finger electrode 3 and twice the spacing between adjacent cross-finger electrodes 3 is taken as the horizontal wavelength λ, and the horizontal wavelength λ is 900 nanometers. The horizontal wavelength λ is proportional to the thickness t of the piezoelectric layer 2. LN The ratio is 3: 1. Based on the above design, the acoustic wave resonator can be used to operate at a frequency of 8.3 GHz.

[0071] Fig.11 A simulated admittance curve of an acoustic wave resonator operating at a frequency of 8.3 GHz provided in an embodiment of the present application. Fig.11 As shown in the simulation admittance curve, the horizontal axis represents frequency (Frequency / GHZ) and the vertical axis represents admittance (Admittance / dB). When the acoustic wave resonator operates at a frequency of 8.3 GHz, the electromechanical coupling coefficient is greater than 9%. The electromechanical coupling coefficient can be calculated using the above formula (1).

[0072] As another possible implementation, the depth d of each groove and the thickness t of each interdigital electrode 3 are e When the ratio is 9:8, the depth d of each groove is 90 nanometers, and the thickness of each interdigital electrode 3 is t e The cross-finger electrode 3 in each groove is completely embedded in the groove. The duty cycle of each cross-finger electrode 3 is 50%. The piezoelectric layer 2 can be cut in the direction of X-cut lithium niobate, and the Euler angle of the piezoelectric layer 2 is -5°. In addition, the sum of twice the width of the cross-finger electrode 3 and twice the spacing between adjacent cross-finger electrodes 3 is taken as the horizontal wavelength λ, and the horizontal wavelength λ is 900 nanometers. The horizontal wavelength λ is proportional to the thickness t of the piezoelectric layer 2. LN The ratio is 9: 1. Based on the above design, the acoustic wave resonator can be used to operate at a frequency of 14.5 GHz.

[0073] Fig.12 A simulated admittance curve of an acoustic wave resonator operating at a frequency of 14.5 GHz provided in an embodiment of the present application. Fig.12 As shown in the simulation admittance curve, the horizontal axis represents frequency (Frequency / GHZ) and the vertical axis represents admittance (Admittance / dB). When the acoustic wave resonator operates at a frequency of 14.5 GHz, the electromechanical coupling coefficient is about 79%. The electromechanical coupling coefficient can be calculated by the above formula (1).

[0074] Based on the above implementation, it can be known that in the embodiment of the present application, by designing the groove depth of the piezoelectric layer, the thickness of the forked electrode and the duty cycle, the forked electrode is embedded in the groove of the piezoelectric layer and goes deeper into the interior of the piezoelectric layer, so that the vibration mode of the excited sound wave is closer to the body wave, that is, it propagates inside the entire medium. Therefore, even in the process of increasing the frequency, there is no need to change the size of the forked electrode, so that the resistance of the forked electrode is not increased, thereby avoiding the reduction of the quality factor of the acoustic wave resonator and realizing a high-quality acoustic wave resonator. In addition, when the ratio of the horizontal wavelength to the thickness of the piezoelectric layer remains unchanged, the operating frequency of the acoustic wave resonator can be from more than ten MHz to more than ten GHz, and a large quality factor is maintained, which can well meet the current frequency band's high frequency and high quality performance requirements for the filter.

[0075] Furthermore, in order to further improve the frequency temperature coefficient of the acoustic wave resonator, in the embodiment of the present application, when a plurality of grooves are provided on the side of the piezoelectric layer 2 facing away from the substrate 1, a silicon dioxide layer may be further covered on the side of at least two interdigitated electrodes 3 facing away from the substrate 1. The thickness of the silicon dioxide layer is 1 to 300 nanometers, for example, the thickness of the silicon dioxide layer may be 1 nanometer, 99 nanometers, 250 nanometers or 300 nanometers. For ease of understanding, the following is an explanation in conjunction with the accompanying drawings and various possible implementations.

[0076] As a possible implementation, Fig.13 A schematic cross-sectional view of an acoustic wave resonator provided in an embodiment of the present application, wherein a silicon dioxide layer is covered on the side of at least two interdigitated electrodes 3 facing away from the substrate 1. Fig.13 As shown, when the interdigital electrode 3 in each groove is completely embedded in the groove and there is still an unfilled part in the groove, the silicon dioxide layer (shown as SiO2 in the figure) can be covered only on the side of at least two interdigital electrodes 3 facing away from the substrate 1.

[0077] As another possible implementation, Fig.14 A cross-sectional schematic diagram of another acoustic wave resonator provided in an embodiment of the present application, wherein a silicon dioxide layer is covered on the side of at least two interdigitated electrodes 3 facing away from the substrate 1. Fig.14 As shown, when the interdigitated electrode 3 in each groove is completely embedded in the groove and there is still an unfilled part in the groove, a silicon dioxide layer (shown as SiO2 in the figure) can be covered on the side of at least two interdigitated electrodes 3 facing away from the substrate 1, and a silicon dioxide layer can be covered on the side of the piezoelectric layer 2 facing away from the substrate 1.

[0078] As another possible implementation, Fig.15 A schematic cross-sectional view of another acoustic wave resonator provided in an embodiment of the present application, wherein a silicon dioxide layer is covered on the side of at least two interdigitated electrodes 3 facing away from the substrate 1. Fig.15As shown, in the case where the interdigitated electrode 3 in each groove is not completely embedded in the groove and there is a portion extending beyond the groove, the side of the interdigitated electrode 3 extending beyond the groove can be covered with a silicon dioxide layer (shown as SiO2 in the figure), and the side of the piezoelectric layer 2 facing away from the substrate 1 can be covered with a silicon dioxide layer.

[0079] Further, Fig.16 A top view of the internal structure of an acoustic wave resonator provided in the present application. Fig.16 As shown, the acoustic wave resonator provided in the embodiment of the present application may include a substrate (not shown in the figure), a piezoelectric layer 2, interdigital electrodes 3 and a reflection grating 4.

[0080] Among them, Fig.16 In the embodiment, the interdigital electrodes 3 include two groups, the two groups of interdigital electrodes 3 are staggered and distributed in a periodic manner, and each group of interdigital electrodes 3 is connected to a bus bar.

[0081] The reflection grid 4 also includes two groups, and the two groups of reflection grids 4 are respectively arranged on both sides of the interdigital electrode 3, and the positions are as follows: Fig.16 As shown. Each reflective grid 4 includes multiple pairs of metal bars, and the number of pairs of metal bars can be 10 to 60, such as 10, 15, 30, 45 or 60. The thickness of each metal bar can be 10 nanometers to 10500 nanometers, for example, the thickness of each metal bar can be 10 nanometers, 100 nanometers, 2900 nanometers, 5000 nanometers, 8900 nanometers, 10000 nanometers or 10500 nanometers. The width of each metal bar can be 0.001 micrometer to 10 micrometers, for example, the width of each metal bar can be 0.001 micrometer, 1 micrometer, 2.6 micrometers, 4.1 micrometers, 7 micrometers, 9.6 micrometers or 10 micrometers. The length of each metal bar can be 1 micrometer to 500 micrometers, for example, the length of each metal bar can be 1 micrometer, 80 micrometers, 250 micrometers, 360 micrometers, 499 micrometers or 500 micrometers.

[0082] In addition, the material of the metal bars of the reflective grid 4 is the same as that of the interdigital electrodes 3, and both have an electrical conductivity greater than 5×10 6 Siemens per meter of metal.

[0083] It should be noted that, in practical applications, the interdigital electrodes can be designed into various shapes, and it is only necessary to ensure that the two groups of interdigital electrodes are staggered and distributed in a periodic manner. Fig.16 This is only an exemplary description and does not limit the specific shape of the interdigital electrodes in the embodiments of the present application.

[0084] Based on the above description of the acoustic wave resonator, it can be known that in an embodiment of the present application, an acoustic wave resonator including a substrate, a piezoelectric layer and at least two interdigitated electrodes can be provided. Wherein, the piezoelectric layer is arranged on the surface of the substrate, and a plurality of grooves are arranged on the side where the piezoelectric layer contacts the substrate or on the side away from the substrate, the depths of the plurality of grooves are all less than the thickness of the piezoelectric layer, the number of the grooves is the same as the number of interdigitated electrodes, and a interdigitated electrode is arranged in each of the plurality of grooves. In this way, the interdigitated electrodes can penetrate deeper into the interior of the piezoelectric layer by being embedded in the grooves of the piezoelectric layer, so that the vibration mode of the excited acoustic wave can be closer to the body wave, that is, propagated throughout the medium. Therefore, even in the process of increasing the frequency, there is no need to change the size of the interdigitated electrodes, so that the resistance of the interdigitated electrodes is not increased, thereby avoiding the reduction of the quality factor of the acoustic wave resonator and realizing a high-quality acoustic wave resonator. Since the interdigitated electrodes are arranged in the grooves of the piezoelectric layer, the interdigitated electrodes are closer to the center of the piezoelectric layer. In addition, the thickness of the interdigitated electrodes can be increased in the grooves so as to increase the cross-section of the interdigitated electrodes, thereby reducing the resistance of the interdigitated electrodes and further improving the quality factor of the acoustic wave resonator.

[0085] Furthermore, based on the acoustic wave resonator provided in the above embodiment, the embodiment of the present application can also provide a method for preparing the acoustic wave resonator. The method for preparing the acoustic wave resonator is described below in combination with the embodiments and the accompanying drawings.

[0086] Fig.17 A flowchart of a method for preparing an acoustic wave resonator provided in an embodiment of the present application. Fig.17 As shown, the method for preparing the acoustic wave resonator provided in the embodiment of the present application may include:

[0087] S1701: Provide a substrate.

[0088] S1702: forming a piezoelectric layer on the surface of the substrate.

[0089] S1703: etching a plurality of grooves on a side where the piezoelectric layer contacts the substrate or a side away from the substrate, wherein the depths of the plurality of grooves are all less than the thickness of the piezoelectric layer.

[0090] S1704: forming an interdigital electrode in each of the plurality of grooves.

[0091] Optionally, a ratio of a depth of each of the plurality of grooves to a thickness of each interdigital electrode is 1:1, 2:1, 3:1 or 9:8.

[0092] Optionally, when the ratio of the depth of each groove to the thickness of each interdigital electrode is 1:1, the acoustic wave resonator is configured to operate at a frequency of 5.3 GHz;

[0093] When the ratio of the depth of each groove to the thickness of each interdigital electrode is 2:1, the acoustic wave resonator is configured to operate at a frequency of 6.6 GHz;

[0094] When the ratio of the depth of each groove to the thickness of each interdigital electrode is 3:1, the acoustic wave resonator is used to operate at a frequency of 8.3 GHz;

[0095] When the ratio of the depth of each groove to the thickness of each interdigital electrode is 9:8, the acoustic wave resonator is configured to operate at a frequency of 14.5 GHz.

[0096] Optionally, the depth of each groove is 10 nanometers to 10,000 nanometers, the thickness of each interdigitated electrode is 10 nanometers to 10,500 nanometers, and the thickness of the piezoelectric layer is 10 nanometers to 10,000 nanometers.

[0097] Optionally, in the case where a plurality of grooves are provided on a side of the piezoelectric layer facing away from the substrate, a silicon dioxide layer is covered on a side of the at least two interdigitated electrodes facing away from the substrate, and a thickness of the silicon dioxide layer is 1 to 300 nanometers.

[0098] Optionally, the piezoelectric layer is a lithium niobate layer, and the Euler angle of the lithium niobate layer is -90° to 90°.

[0099] Optionally, each interdigital electrode has an electrical conductivity greater than 5×10 6 Siemens per meter of metal.

[0100] Optionally, the substrate includes at least one of silicon, aluminum oxide, silicon oxide, glass, aluminum nitride, scandium aluminum nitride, quartz or silicon carbide.

[0101] Furthermore, based on the acoustic wave resonator provided in the above embodiment, the embodiment of the present application can also provide an electronic device. The electronic device includes the acoustic wave resonator provided in any of the above embodiments.

[0102] It should be noted that the various embodiments in this specification are described in a progressive, parallel, or progressive and parallel manner, and each embodiment focuses on the differences from other embodiments, and the same or similar parts between the various embodiments can be referred to each other. For the preparation method disclosed in the embodiment, since it corresponds to the acoustic wave resonator disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the description of the acoustic wave resonator part.

[0103] It should also be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0104] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An acoustic wave resonator, characterized in that: include: a substrate, a piezoelectric layer, and at least two interdigitated electrodes; The piezoelectric layer is arranged on the surface of the substrate, and a plurality of grooves are arranged on the side of the piezoelectric layer contacting the substrate or on the side away from the substrate, the depths of the plurality of grooves are all less than the thickness of the piezoelectric layer, the number of the grooves is the same as the number of the interdigital electrodes, and an interdigital electrode is arranged in each of the plurality of grooves; The ratio of the depth of each groove in the plurality of grooves to the thickness of each interdigital electrode is in the range of 0.5 to 10; Wherein, when the ratio of the depth of each groove to the thickness of each interdigital electrode is 1:1, the acoustic wave resonator is used to operate at a frequency of 5.3 GHz; When the ratio of the depth of each groove to the thickness of each interdigital electrode is 2:1, the acoustic wave resonator is configured to operate at a frequency of 6.6 GHz; When the ratio of the depth of each groove to the thickness of each interdigital electrode is 3:1, the acoustic wave resonator is used to operate at a frequency of 8.3 GHz; When the ratio of the depth of each groove to the thickness of each interdigital electrode is 9:8, the acoustic wave resonator is configured to operate at a frequency of 14.5 GHz.

2. The acoustic wave resonator according to claim 1, characterized in that The depth of each groove is 10 nanometers to 10,000 nanometers, the thickness of each interdigital electrode is 10 nanometers to 10,500 nanometers, and the thickness of the piezoelectric layer is 10 nanometers to 10,000 nanometers.

3. The acoustic wave resonator according to claim 1, characterized in that In the case where a plurality of grooves are provided on a side of the piezoelectric layer facing away from the substrate, a silicon dioxide layer is covered on a side of the at least two interdigitated electrodes facing away from the substrate, and a thickness of the silicon dioxide layer is 1 to 300 nanometers.

4. The acoustic wave resonator according to claim 1, characterized in that The piezoelectric layer is a lithium niobate layer, and the Euler angle of the lithium niobate layer is -90° to 90°.

5. The acoustic wave resonator according to claim 1, characterized in that Each interdigital electrode has a conductivity greater than 5×10 6 Siemens per meter of metal.

6. The acoustic wave resonator according to claim 1, characterized in that The substrate includes at least one of silicon, aluminum oxide, silicon oxide, glass, aluminum nitride, scandium aluminum nitride, quartz or silicon carbide.

7. A method for preparing an acoustic wave resonator, characterized in that: include: providing a substrate; forming a piezoelectric layer on a surface of the substrate; Etching a plurality of grooves on a side of the piezoelectric layer contacting the substrate or on a side away from the substrate, wherein the depths of the plurality of grooves are all less than the thickness of the piezoelectric layer; forming an interdigitated electrode in each of the plurality of grooves; The ratio of the depth of each groove in the plurality of grooves to the thickness of each interdigital electrode is in the range of 0.5 to 10; Wherein, when the ratio of the depth of each groove to the thickness of each interdigital electrode is 1:1, the acoustic wave resonator is used to operate at a frequency of 5.3 GHz; When the ratio of the depth of each groove to the thickness of each interdigital electrode is 2:1, the acoustic wave resonator is configured to operate at a frequency of 6.6 GHz; When the ratio of the depth of each groove to the thickness of each interdigital electrode is 3:1, the acoustic wave resonator is used to operate at a frequency of 8.3 GHz; When the ratio of the depth of each groove to the thickness of each interdigital electrode is 9:8, the acoustic wave resonator is configured to operate at a frequency of 14.5 GHz.

8. An electronic device, characterized in that: Comprising the acoustic wave resonator according to any one of claims 1 to 6.

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