Surface acoustic wave resonance device and filtering device

Abstract

The utility model provides a surface acoustic wave resonance device and a filtering device. The surface acoustic wave resonance device comprises a substrate; an intermediate layer on the substrate; the piezoelectric layer is located on the middle layer, the material of the piezoelectric layer comprises Y-X cut lithium niobate, the cut angle ranges from 20 degrees to 45 degrees, the thickness range of the piezoelectric layer ranges from 0.08 to 0.35, and the wave length of the piezoelectric layer is the wave length of surface acoustic waves; the interdigital transducer is positioned on the piezoelectric layer; the influence of clutters on the performance of the surface acoustic wave resonance device can be obviously inhibited, the electromechanical coupling coefficient and the wave velocity are improved, and the application range is wide.

Description

Technical Field

[0001] This utility model relates to the field of acoustic resonance device technology, and in particular to a surface acoustic wave resonator and a filtering device. Background Technology

[0002] Radio frequency (RF) front-end chips in wireless communication devices include power amplifiers, antenna switches, RF filters, multiplexers, and low-noise amplifiers. Among these, RF filters include surface acoustic wave (SAW) filters, bulk acoustic wave (BAW) filters, micro-electro-mechanical system (MEMS) filters, and integrated passive device (IPD) filters.

[0003] Surface acoustic wave (SAW) resonators have a high quality factor (Q value). SAW resonators are used to manufacture radio frequency (RF) filters with low insertion loss and high out-of-band rejection. These SAW resonators are the mainstream RF filters used in mobile phones, base stations, and other wireless communication devices.

[0004] However, the performance of existing surface acoustic wave resonators still needs improvement. Utility Model Content

[0005] The technical problem solved by this utility model is to provide a surface acoustic wave resonator and a filter device, which can improve the electromechanical coupling coefficient and wave velocity, and has a wide range of applications.

[0006] To address the aforementioned problems, this invention provides a surface acoustic wave (SAW) resonator, comprising a substrate; an intermediate layer on the substrate; and a piezoelectric layer on the intermediate layer. The piezoelectric layer is made of YX-cut lithium niobate with a cut angle ranging from 20° to 45°, and the thickness of the piezoelectric layer ranges from 0.08 mm. Up to 0.35 , The wavelength of the surface acoustic wave; the interdigital transducer located on the piezoelectric layer.

[0007] Optionally, the thickness of the piezoelectric layer is in the range of 0.2 mm. Up to 0.3 .

[0008] Optionally, the thickness of the intermediate layer is greater than 0.66. .

[0009] Optionally, the interdigital transducer may be made of one or more of aluminum, molybdenum, copper, platinum, gold, and tungsten.

[0010] Optionally, the material of the intermediate layer includes silicon dioxide, silicon oxynitride, silicon oxycarbide, or silicon oxyfluoride.

[0011] Optionally, the substrate material includes silicon, silicon carbide, or diamond.

[0012] Accordingly, the present invention also provides a filtering device, including: the surface acoustic wave resonator device described in any of the above claims.

[0013] Compared with the prior art, the technical solution of this utility model has the following advantages:

[0014] In the technical solution of the surface acoustic wave resonator of this utility model, the piezoelectric layer material includes YX-cut lithium niobate with a cut angle ranging from 20° to 45°, resulting in a larger electromechanical coupling coefficient and wave velocity; furthermore, the thickness of the piezoelectric layer ranges from 0.08 mm. Up to 0.35 , The wavelength of surface acoustic waves is given. By controlling the thickness of the piezoelectric layer, the influence of clutter on the performance of surface acoustic wave resonators can be significantly suppressed, and it has a wide range of applications.

[0015] Furthermore, the thickness of the piezoelectric layer ranges from 0.2 mm. Up to 0.3 This can further suppress the influence of clutter on the performance of surface acoustic wave resonators, while having little impact on the electromechanical coupling coefficient and wave velocity. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a surface acoustic wave resonator in one embodiment;

[0017] Figure 2 This is a schematic diagram of the structure of a surface acoustic wave resonator in one embodiment of the present invention;

[0018] Figure 3 This diagram shows the relationship between the electromechanical coupling coefficient (Kt), wave velocity, and piezoelectric layer chamfer angle in this invention.

[0019] Figure 4 This is an admittance diagram corresponding to different piezoelectric layer chamfer angles in this invention;

[0020] Figure 5 This is a diagram showing the relationship between the electromechanical coupling coefficient, wave velocity, and the thickness of the piezoelectric layer in one embodiment of this utility model.

[0021] Figure 6This is an admittance diagram corresponding to different piezoelectric layer thicknesses in one embodiment of this utility model;

[0022] Figure 7 This is an admittance diagram corresponding to the thickness of different intermediate layers in Embodiment 2 of this utility model;

[0023] Figure 8 This is an admittance diagram corresponding to the thicknesses of two different intermediate layers in Embodiment 2 of this utility model. Detailed Implementation

[0024] As mentioned in the background section, the performance of surface acoustic wave resonators still faces many challenges.

[0025] Please refer to Figure 1 A surface acoustic wave resonator includes: a piezoelectric layer 100, an interdigitated electrode structure 101 on the piezoelectric layer 100, the material of the piezoelectric layer 100 being lithium niobate (LiNbO3, LN) or lithium tantalate (LiTaO3, LT); and a temperature compensation layer 102 on the piezoelectric layer 100, the temperature compensation layer 102 covering the interdigitated electrode structure 101.

[0026] The inventors discovered that surface acoustic wave resonator devices based on lithium niobate (LiNbO3, LN) or lithium tantalate (LiTaO3, LT) monomer bulk materials are limited by material properties, and have disadvantages such as low operating frequency (<2.5GHz), small electromechanical coupling coefficient (less than 8%), high temperature frequency coefficient (TCF), and poor power handling characteristics.

[0027] The inventors discovered through research that by including YX-cut lithium niobate as the piezoelectric layer material in the surface acoustic wave resonator, with a cut angle ranging from 20° to 45°, a larger electromechanical coupling coefficient and wave velocity can be obtained; furthermore, the thickness of the piezoelectric layer ranges from 0.08 mm. Up to 0.35 , The wavelength of surface acoustic waves is given. By controlling the thickness of the piezoelectric layer, the influence of clutter on the performance of surface acoustic wave resonators can be significantly suppressed, and it has a wide range of applications.

[0028] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings.

[0029] First, please refer to Figure 2 A surface acoustic wave resonator 200 includes: a substrate 201; an intermediate layer 202 located on the substrate 201; and a piezoelectric layer 203 located on the intermediate layer 202. The piezoelectric layer 203 is made of YX-cut lithium niobate with a cut angle ranging from 20° to 45°, and the thickness of the piezoelectric layer 203 ranges from 0.08 mm. Up to 0.35 , The wavelength of the surface acoustic wave is denoted as λ; the interdigital transducer 204 is located on the piezoelectric layer 203.

[0030] In this embodiment, lithium niobate, as a piezoelectric material, exhibits anisotropy, and its acoustic properties are affected by different tangential and propagation directions. By optimizing the tangential direction and film thickness, its electromechanical coupling coefficient can be enhanced, making it suitable for high-frequency (such as 5G) communication system applications.

[0031] Please refer to Figure 3 , Figure 3 The graph shows the relationship between the electromechanical coupling coefficient (Kt) and wave velocity for different chamfer angles of the piezoelectric layer (YX-LN) 203.

[0032] from Figure 3 It can be seen that the chamfer of the piezoelectric layer (LN) 203 ranges from 20° to 45°, corresponding to a wave velocity range of 3900-4000 m / s, and the electromechanical coupling coefficient of the resonator is relatively large.

[0033] In this embodiment, the main resonant mode of the surface acoustic wave resonator 200 is a horizontal shear wave (SH).

[0034] In this embodiment, by selecting the appropriate chamfer angle, the dispersion of sound wave energy can be suppressed. Please refer to... Figure 4 , Figure 4 For admittance diagrams corresponding to different piezoelectric layer chamfer angles, from Figure 4 It can be seen that when the chamfer of the piezoelectric layer (LN) 203 is in the range of 20° to 45°, the main resonant mode is SH wave, the admittance ratio corresponding to the clutter mode is significantly reduced, and the clutter suppression effect is obvious.

[0035] The thickness of the piezoelectric layer 203 ranges from 0.08 mm. Up to 0.35 It can significantly suppress the influence of clutter on the performance of surface acoustic wave resonators.

[0036] Preferably, the thickness of the piezoelectric layer 203 is in the range of 0.2 mm. Up to 0.3 This can further suppress the influence of clutter on the performance of the surface acoustic wave resonator 200, while having little impact on the electromechanical coupling coefficient and wave velocity.

[0037] In this embodiment, the substrate 201 is made of a high-velocity material, including silicon, silicon carbide, or diamond.

[0038] The intermediate layer 202 has a positive temperature drift coefficient and has the opposite temperature frequency shift characteristics to the piezoelectric layer 203. This helps to reduce the temperature coefficient of frequency (TCF) of the surface acoustic wave resonator 200, thereby achieving higher frequency-temperature stability and preventing the operating frequency of the surface acoustic wave resonator 200 from drifting with the operating temperature.

[0039] In this embodiment, the thickness of the intermediate layer 202 is greater than 0.66 mm. It can significantly suppress the influence of clutter on the performance of surface acoustic wave resonators, while having a relatively small impact on the electromechanical coupling coefficient.

[0040] In this embodiment, the material of the intermediate layer 202 includes silicon dioxide, silicon oxynitride, silicon oxycarbonate, or silicon oxyfluoride.

[0041] In some embodiments, the intermediate layer 202 is a silicon dioxide thin film grown by plasma-enhanced chemical vapor deposition (PECVD). PECVD is a low-temperature process that can perform large-area deposition, resulting in a more uniform thickness of the silicon dioxide thin film.

[0042] The thickness of the piezoelectric layer 203 ranges from 0.08 mm. Up to 0.35 When the thickness of the piezoelectric layer 203 is less than 0.08... When the thickness of the piezoelectric layer 203 is greater than 0.35 mm, it will lead to a smaller bandwidth, and clutter will have a significant impact on the performance of the surface acoustic wave resonator 200; when the thickness of the piezoelectric layer 203 is greater than 0.35 mm... This can lead to a decrease in bandwidth, and clutter can significantly impact the performance of the surface acoustic wave resonator 200. The thickness of the intermediate layer 202 is greater than 0.66 mm. When the thickness of the intermediate layer 202 is less than 0.66 At that time, clutter has a significant impact on the performance of surface acoustic wave resonators.

[0043] In this embodiment, the interdigital transducer 204 is made of one or more of aluminum, molybdenum, copper, platinum, gold and tungsten.

[0044] In this embodiment, the interdigital transducer 204 has a single-layer structure.

[0045] In some embodiments, the interdigital transducer 204 may also be a stacked structure.

[0046] The present invention will now be described in detail with reference to the embodiments and accompanying drawings.

[0047] Example 1

[0048] A surface acoustic wave resonator 200, please refer to the following reference. Figure 2It includes: a substrate 201; an intermediate layer 202 located on the substrate 201; and a piezoelectric layer 203 located on the intermediate layer 202. The piezoelectric layer 203 is made of YX-cut lithium niobate with a cut angle of 41° and a thickness ranging from 0.08 mm. Up to 0.35 Interdigital transducers 204 located on the piezoelectric layer 203.

[0049] Figure 5 To implement a graph showing the relationship between electromechanical coupling coefficient, wave velocity, and piezoelectric layer thickness, Figure 6 To implement admittance plots for different piezoelectric layer thicknesses, Figure 6 The percentages corresponding to each curve represent the ratio of the piezoelectric layer thickness to the wavelength of the surface acoustic wave.

[0050] Please refer to Figure 6 The thickness of the piezoelectric layer 203 ranges from 0.08 mm. Up to 0.35 This achieves significant suppression of high-frequency clutter modes.

[0051] Preferably, the thickness of the piezoelectric layer 203 is in the range of 0.2 mm. Up to 0.3 .

[0052] Please refer to Figure 5 The thickness of the piezoelectric layer 203 ranges from 0.2 mm. Up to 0.3 This can further suppress the influence of clutter on the performance of the surface acoustic wave resonator 200, while having little impact on the electromechanical coupling coefficient and wave velocity.

[0053] Example 2

[0054] A surface acoustic wave resonator 200, please refer to the following reference. Figure 2 The device includes: a substrate 201; an intermediate layer 202 located on the substrate 201; a piezoelectric layer 203 located on the intermediate layer 202, the material of the piezoelectric layer 203 including YX-cut lithium niobate with a cut angle of 41°; an interdigital transducer 204 located on the piezoelectric layer 203, and the intermediate layer 202 being silicon dioxide.

[0055] The normalized thickness range of the intermediate layer 202 is preferably greater than 0.66 mm. By introducing an intermediate layer 202 with a positive temperature drift coefficient, the temperature coefficient of the surface acoustic wave resonator can be compensated, and the intermediate layer 202 can keep clutter away from the main resonance peak.

[0056] Figure 7 To implement admittance plots corresponding to the different thicknesses of the two intermediate layers, Figure 7 The percentages corresponding to each curve represent the ratio of the thickness of the intermediate layer to the wavelength of the surface acoustic wave. Figure 7 It can be seen that the thickness of the intermediate layer 202 is greater than 0.66. At this time, it can keep low-frequency noise away from the main resonance peak and significantly suppress the influence of low-frequency noise on the performance of surface acoustic wave resonators.

[0057] This embodiment includes Sample1 and Sample2. The difference between Sample1 and Sample2 is that the thickness of the intermediate layer is different.

[0058] Sample 1: A surface acoustic wave resonator 200, please refer to the reference. Figure 2 The device includes: a substrate 201; an intermediate layer 202 located on the substrate 201, the intermediate layer 202 being made of silicon dioxide and having a thickness of 280 nm; a piezoelectric layer 203 located on the intermediate layer 202, the piezoelectric layer 203 being made of 41°YX-LN and having a thickness of 280 nm; and an interdigital transducer 204 located on the piezoelectric layer 203, the interdigital transducer 204 being made of aluminum and having a thickness of 80 nm.

[0059] Sample 2: A surface acoustic wave resonator 200, please refer to the reference. Figure 2 The device includes: a substrate 201; an intermediate layer 202 located on the substrate 201, the intermediate layer 202 being made of silicon dioxide and having a thickness of 600 nm; a piezoelectric layer 203 located on the intermediate layer 202, the piezoelectric layer 203 being made of 41°YX-LN and having a thickness of 280 nm; and an interdigital transducer 204 located on the piezoelectric layer 203, the interdigital transducer 204 being made of aluminum and having a thickness of 80 nm.

[0060] Figure 8 For the admittance diagrams corresponding to Sample1 and Sample2, from Figure 8 It can be seen that when the thickness of the intermediate layer 202 is 600nm (Sample2), low-frequency clutter is significantly suppressed. Increasing the thickness of the intermediate layer 202 film can significantly reduce the influence of clutter and improve the Q value of the surface acoustic wave resonator.

[0061] Accordingly, this utility model also provides a filtering device, including: the surface acoustic wave resonator device described in any of the above embodiments, wherein the piezoelectric layer material in the surface acoustic wave resonator device includes YX-cut lithium niobate with a cut angle ranging from 20° to 45°, thereby obtaining a larger electromechanical coupling coefficient and wave velocity; furthermore, the thickness of the piezoelectric layer ranges from 0.08 mm. Up to 0.35 , The wavelength of surface acoustic waves is given. By controlling the thickness of the piezoelectric layer, the influence of clutter on the performance of surface acoustic wave resonators can be significantly suppressed, and it has a wide range of applications.

[0062] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A surface acoustic wave resonator device, characterized by, Comprising: a substrate; an intermediate layer on the substrate; a piezoelectric layer on the intermediate layer, the material of the piezoelectric layer comprising Y-X cut lithium niobate, the cut angle ranging from 20° to 45°, the thickness of the piezoelectric layer ranging from 0.08 to 0.35 , is the wavelength of the surface acoustic wave; an interdigital transducer on the piezoelectric layer.

2. The SAW resonator device of claim 1, wherein, The thickness of the piezoelectric layer ranges from 0.2 to 0.3 .

3. The SAW resonator device of claim 1, wherein, the thickness of the intermediate layer is greater than 0.66 .

4. The SAW resonator device of claim 1, wherein, The material of the interdigital transducer comprises one of aluminum, molybdenum, copper, platinum, gold and tungsten.

5. The SAW resonator device of claim 1, wherein, The material of the intermediate layer comprises silicon dioxide, silicon oxynitride, silicon oxycarbide or silicon oxyfluoride.

6. The SAW resonator device of claim 1, wherein, The material of the substrate comprises silicon, silicon carbide or diamond.

7. A filtering device, characterized in that Comprising: a surface acoustic wave resonator device as claimed in any one of claims 1 to 6.

Images