Surface acoustic wave resonance device and filtering device

Abstract

The utility model provides a surface acoustic wave resonance device and a filtering device wherein the surface acoustic wave resonance device comprises a substrate; the middle layer is positioned 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 range is 140 degrees to 170 degrees, the thickness range of the piezoelectric layer is 0.27 lambda to 0.5 lambda, and lambda is the wavelength of surface acoustic waves; the interdigital transducer is positioned on the piezoelectric layer; the temperature compensation layer is located on the piezoelectric layer, and the temperature compensation layer covers the interdigital transducer; the large electromechanical coupling coefficient (Kt) is obtained by selecting the corner cut of the piezoelectric layer, the electromechanical coupling coefficient and the wave velocity can be further improved by controlling the thickness of the piezoelectric layer, 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 filter 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 filtering 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 utility model provides a surface acoustic wave (SAW) resonator, comprising: a substrate; an intermediate layer on the substrate; a piezoelectric layer on the intermediate layer, wherein the piezoelectric layer is made of YX-cut lithium niobate with a cut angle ranging from 140° to 170° and a thickness ranging from 0.27λ to 0.5λ, where λ is the wavelength of the SAW; an interdigital transducer on the piezoelectric layer; and a temperature compensation layer on the piezoelectric layer, the temperature compensation layer covering the interdigital transducer.

[0007] Optionally, the thickness of the piezoelectric layer ranges from 0.37λ to 0.4λ.

[0008] Optionally, the thickness of the temperature compensation layer ranges from 0.208λ to 0.58λ.

[0009] Optionally, the thickness of the temperature compensation layer ranges from 0.25λ to 0.46λ.

[0010] Optionally, the interdigital transducer may be made of one or more of aluminum, molybdenum, copper, platinum, gold, and tungsten.

[0011] Optionally, the interdigital transducer includes a first metal layer on the piezoelectric layer and a second metal layer on the first metal layer, wherein the material of the first metal layer includes molybdenum and the material of the second metal layer includes aluminum or an aluminum alloy.

[0012] Optionally, the thickness of the first metal layer ranges from 0.083λ to 0.33λ.

[0013] Optionally, the thickness of the first metal layer ranges from 0.125λ to 0.167λ.

[0014] Optionally, the thickness of the second metal layer ranges from 0.033λ to 0.16λ.

[0015] Optionally, the material of the temperature compensation layer includes silicon dioxide, silicon oxynitride, silicon oxycarbonate, or silicon oxyfluoride.

[0016] Optionally, the substrate material may include silicon, silicon carbide, or diamond.

[0017] Optionally, the material of the intermediate layer includes silicon dioxide, silicon oxynitride, silicon oxycarbide, or silicon oxyfluoride.

[0018] Accordingly, the present invention also provides a filtering device, including: the surface acoustic wave resonator device described in any of the above claims.

[0019] Compared with the prior art, the technical solution of this utility model has the following advantages:

[0020] 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 cutting angle ranging from 140° to 170° to obtain a large electromechanical coupling coefficient (Kt); in addition, the thickness of the piezoelectric layer ranges from 0.27λ to 0.5λ, where λ is the wavelength of the surface acoustic wave. By controlling the thickness of the piezoelectric layer, the electromechanical coupling coefficient and wave velocity can be further improved, and it has a wider range of applications.

[0021] Furthermore, the thickness of the piezoelectric layer ranges from 0.37λ to 0.4λ, which can significantly suppress the influence of clutter on the performance of the surface acoustic wave resonator. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of a surface acoustic wave resonator in one embodiment;

[0023] Figure 2 This is a schematic diagram of the structure of a surface acoustic wave resonator in one embodiment of the present invention;

[0024] Figure 3 This is a graph showing the relationship between the electromechanical coupling coefficient (Kt), wave velocity, and the thickness of the piezoelectric layer in one embodiment of this utility model.

[0025] Figure 4 This is an admittance diagram corresponding to different piezoelectric layer thicknesses in one embodiment of this utility model;

[0026] Figure 5 This is a graph showing the relationship between the electromechanical coupling coefficient (Kt), wave velocity, and the thickness of the temperature compensation layer in Embodiment 2 of this utility model.

[0027] Figure 6 The admittance diagrams are shown for the thicknesses of the temperature compensation layers in Embodiment 2 of this utility model.

[0028] Figure 7 This is a graph showing the relationship between the electromechanical coupling coefficient (Kt), wave velocity, and the thickness of the first metal layer in Embodiment 3 of this utility model.

[0029] Figure 8 This is an admittance diagram corresponding to different thicknesses of the first metal layer in Embodiment 3 of this utility model. Detailed Implementation

[0030] As described in the background section, surface acoustic wave resonator devices still have many problems. These will be explained in detail below with reference to the accompanying drawings.

[0031] Figure 1 This is a schematic diagram of the structure of a surface acoustic wave resonator.

[0032] 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.

[0033] 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 (Kt) (less than 8%), high temperature frequency coefficient (TCF), and poor power handling characteristics.

[0034] Through research, the inventors discovered that using YX-cut lithium niobate as the material for the piezoelectric layer in the surface acoustic wave resonator, with a cutting angle ranging from 140° to 170°, can achieve a larger electromechanical coupling coefficient (Kt) than that of YX-cut lithium niobate with a cutting angle of 127° to 129°. Furthermore, the thickness of the piezoelectric layer ranges from 0.27λ to 0.5λ, where λ is the wavelength of the surface acoustic wave. By controlling the thickness of the piezoelectric layer, the electromechanical coupling coefficient and wave velocity can be further improved, resulting in a wider range of applications.

[0035] 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.

[0036] First, please refer to Figure 2 A surface acoustic wave (SAW) resonator includes a substrate 200, an intermediate layer 201 on the substrate 200, a piezoelectric layer 202 on the intermediate layer 201, the piezoelectric layer 202 being made of YX-cut lithium niobate with a cut angle ranging from 140° to 170° and a thickness ranging from 0.27λ to 0.5λ, where λ is the wavelength of the SAW, an interdigital transducer 203 on the piezoelectric layer 202, and a temperature compensation layer 204 on the piezoelectric layer 202, the temperature compensation layer 204 covering the interdigital transducer 203.

[0037] 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.

[0038] The piezoelectric layer material includes YX-cut lithium niobate with a cut angle ranging from 140° to 170°, which can obtain a larger electromechanical coupling coefficient (Kt) than that of YX-cut lithium niobate with a cut angle of 127° to 129°; the thickness of the piezoelectric layer ranges from 0.27λ to 0.5λ, which can further improve the electromechanical coupling coefficient and wave velocity.

[0039] Preferably, the thickness of the piezoelectric layer 202 is in the range of 0.37λ to 0.4λ, which can significantly suppress the influence of clutter on the performance of the surface acoustic wave resonator.

[0040] In this embodiment, the substrate 200 is made of silicon, silicon carbide, or diamond.

[0041] In this embodiment, the material of the intermediate layer 201 includes silicon dioxide, silicon oxynitride, silicon oxycarbonate, or silicon oxyfluoride.

[0042] The temperature compensation layer 204 has temperature frequency shift characteristics opposite to those of the piezoelectric layer 202, which helps to reduce the temperature coefficient of frequency (TCF) of the surface acoustic wave resonator, thereby achieving higher frequency-temperature stability and preventing the operating frequency of the surface acoustic wave resonator from drifting with the operating temperature.

[0043] In this embodiment, the thickness of the temperature compensation layer 204 ranges from 0.208λ to 0.58λ. Under the optimized film thickness conditions, the temperature compensation effect of the temperature compensation layer 204 is quite obvious.

[0044] Preferably, the thickness of the temperature compensation layer 204 ranges from 0.25λ to 0.46λ. This can significantly suppress the influence of clutter on the performance of the surface acoustic wave resonator, while having a relatively small impact on the electromechanical coupling coefficient.

[0045] In this embodiment, the temperature compensation layer 204 is made of silicon dioxide, silicon oxynitride, silicon oxycarbonate, or silicon oxyfluoride.

[0046] In some embodiments, the temperature compensation layer 204 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.

[0047] The thickness of the piezoelectric layer 202 ranges from 0.27λ to 0.5λ. When the thickness of the piezoelectric layer 202 is too low, the bandwidth will be smaller, and clutter will have a greater impact on the performance of the surface acoustic wave resonator. When the thickness of the piezoelectric layer 202 is too high, clutter will also have a greater impact on the performance of the surface acoustic wave resonator. The thickness of the temperature compensation layer 204 ranges from 0.208λ to 0.58λ. When the thickness of the temperature compensation layer 204 is too low, clutter will have a greater impact on the performance of the surface acoustic wave resonator. When the thickness of the temperature compensation layer 204 is too high, the bandwidth will be smaller, and clutter will also have a greater impact on the performance of the surface acoustic wave resonator.

[0048] In this embodiment, the interdigital transducer 203 is made of one or more of aluminum, molybdenum, copper, platinum, gold and tungsten.

[0049] In this embodiment, the interdigital transducer 203 includes a first metal layer 203a located on the piezoelectric layer 202 and a second metal layer 203b located on the first metal layer 203a.

[0050] The material of the first metal layer 203a includes molybdenum, and the thickness of the first metal layer 203a ranges from 0.083λ to 0.33λ.

[0051] Preferably, the thickness of the first metal layer 203a ranges from 0.125λ to 0.167λ. This can significantly suppress the influence of clutter on the performance of the surface acoustic wave resonator, while having a relatively small impact on the electromechanical coupling coefficient and wave velocity.

[0052] In this embodiment, the material of the second metal layer 203b includes aluminum or aluminum alloy, and the thickness of the second metal layer 203b ranges from 0.033λ to 0.16λ.

[0053] The present invention will now be described in detail with reference to the embodiments and accompanying drawings.

[0054] Example 1

[0055] A surface acoustic wave resonator, please refer to the reference. Figure 2 The system includes a substrate 200, an intermediate layer 201 on the substrate 200, a piezoelectric layer (LN) 202 on the intermediate layer 201, the material of the piezoelectric layer (LN) 202 including YX-cut lithium niobate with a cut angle ranging from 140° to 170° and a thickness ranging from 0.27λ to 0.5λ, where λ is the wavelength of the surface acoustic wave, an interdigital transducer 203 on the piezoelectric layer (LN) 202, and a piezoelectric layer (LN) 203 on the intermediate layer 201. A temperature compensation layer 204 is placed on layer (LN) 202, covering the interdigital transducer 203; wherein, λ is 1.225um, the chamfer is 170°YX, the thickness of substrate 200 is 1um, the thickness of intermediate layer 201 is 0.41λ, the thickness of temperature compensation layer 204 is 0.33λ, the thickness of first metal layer 203a is 0.125λ, and the thickness of second metal layer 203b is 0.081λ.

[0056] Figure 3 The graph shows the relationship between the electromechanical coupling coefficient (Kt), wave velocity, and the thickness of the piezoelectric layer (LN) 202 when the thickness ranges from 0.27λ to 0.5λ.

[0057] from Figure 3 It can be seen that when the thickness of the piezoelectric layer (LN)202 is in the range of 0.27λ to 0.5λ, it has a large wave velocity, and when the thickness of the piezoelectric layer (LN)202 is greater than 0.3λ, Kt tends to be stable.

[0058] Please refer to Figure 4 To obtain the admittance plots for different thicknesses of the piezoelectric layer (LN) 202 within the thickness range of 0.27λ to 0.5λ, from... Figure 4 It can be seen that the thickness of the piezoelectric layer (LN)202 is between 0.37λ and 0.4λ, and the clutter suppression effect is obvious.

[0059] Example 2

[0060] A surface acoustic wave resonator, please refer to the reference. Figure 2 The system includes a substrate 200, an intermediate layer 201 on the substrate 200, a piezoelectric layer (LN) 202 on the intermediate layer 201, the material of the piezoelectric layer (LN) 202 including YX-cut lithium niobate with a cut angle ranging from 140° to 170°, an interdigital transducer 203 on the piezoelectric layer (LN) 202, and a temperature compensation layer (TC-SiO2) 204 on the piezoelectric layer (LN) 202, the temperature compensation layer (TC-SiO2) 204 covering the interdigital transducer 203; wherein, λ is 1.225um, the cut angle is 170°YX, the thickness of the substrate 200 is 1um, the thickness of the intermediate layer 201 is 0.41λ, the thickness of the piezoelectric layer (LN) 202 is 0.4λ, the thickness of the first metal layer 203a is 0.125λ, and the thickness of the second metal layer 203b is 0.081λ.

[0061] Figure 5 The graph shows the relationship between the electromechanical coupling coefficient (Kt), wave velocity, and the thickness of the temperature compensation layer (TC-SiO2)204 when the thickness ranges from 0.208λ to 0.58λ.

[0062] from Figure 5 It can be seen that when the thickness of the temperature compensation layer (TC-SiO2)2O4 is in the range of 0.25λ to 0.46λ, the effect on Kt and wave velocity is relatively small.

[0063] Please refer to Figure 6 The admittance plots are presented for different thicknesses of the temperature compensation layer (TC-SiO2)204 within the thickness range of 0.208λ to 0.58λ. Figure 6 It can be seen that the thickness of the temperature compensation layer (TC-SiO2)204 ranges from 0.25λ to 0.46λ, and the clutter suppression effect is obvious with no obvious clutter.

[0064] Example 3

[0065] A surface acoustic wave resonator, please refer to the reference. Figure 2The system includes a substrate 200, an intermediate layer 201 on the substrate 200, a piezoelectric layer (LN) 202 on the intermediate layer 201, the material of the piezoelectric layer (LN) 202 including YX-cut lithium niobate with a cut angle ranging from 140° to 170°, an interdigital transducer 203 on the piezoelectric layer (LN) 202, and a temperature compensation layer (TC-SiO2) 204 on the piezoelectric layer (LN) 202, the temperature compensation layer (TC-SiO2) 204 covering the interdigital transducer 203; wherein, λ is 1.225um, the cut angle is 170°YX, the thickness of the substrate 200 is 1um, the thickness of the intermediate layer 201 is 0.41λ, the thickness of the piezoelectric layer (LN) 202 is 0.4λ, and the thickness of the temperature compensation layer (TC-SiO2) 204 is 0.33λ.

[0066] Figure 7 The graph shows the relationship between the electromechanical coupling coefficient (Kt), wave velocity, and the thickness of the first metal layer (Mo) 203a when the thickness ranges from 0.083λ to 0.33λ.

[0067] from Figure 7 It can be seen that when the thickness of the first metal layer (Mo)₂O₃a is in the range of 0.125λ to 0.167λ, the effect on Kt and wave velocity is relatively small.

[0068] Please refer to Figure 8 For admittance plots corresponding to different thicknesses of the first metal layer 203a within the thickness range of 0.083λ to 0.33λ, from... Figure 8 It can be seen that the thickness of the first metal layer 203a ranges from 0.125λ to 0.167λ, with minimal clutter influence and a significant clutter suppression effect.

[0069] The thickness of the second metal layer 203b ranges from 0.033λ to 0.16λ.

[0070] Accordingly, this utility model also provides a filtering device, including: the surface acoustic wave resonator device described in any of the above embodiments. Since the material of the piezoelectric layer (LN) 202 in the surface acoustic wave resonator device includes YX-cut lithium niobate with a cut angle range of 140° to 170°, a large electromechanical coupling coefficient (Kt) is obtained. In addition, the thickness of the piezoelectric layer (LN) 202 ranges from 0.27λ to 0.5λ, where λ is the wavelength of the surface acoustic wave. By controlling the thickness of the piezoelectric layer (LN) 202, the electromechanical coupling coefficient and wave velocity can be further improved, and it has a wider range of applications.

[0071] 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 140° to 170°, the thickness of the piezoelectric layer ranging from 0.27λ to 0.5λ, λ being the wavelength of the surface acoustic wave; an interdigital transducer on the piezoelectric layer; a temperature compensation layer on the piezoelectric layer, the temperature compensation layer covering the interdigital transducer.

2. The SAW resonator device of claim 1, wherein, The thickness of the piezoelectric layer ranges from 0.37λ to 0.4λ.

3. The SAW resonator device of claim 1, wherein, The thickness of the temperature compensation layer ranges from 0.208λ to 0.58λ.

4. The SAW resonator device of claim 3, wherein, The thickness of the temperature compensation layer ranges from 0.25λ to 0.46λ.

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

6. The SAW resonator device of claim 1, wherein, The interdigital transducer comprises a first metal layer on the piezoelectric layer and a second metal layer on the first metal layer, the material of the first metal layer comprising molybdenum, the material of the second metal layer comprising aluminum or an aluminum alloy.

7. The SAW resonator device of claim 6, wherein, The thickness of the first metal layer ranges from 0.083λ to 0.33λ.

8. The SAW resonator device of claim 7, wherein, The thickness of the first metal layer ranges from 0.125λ to 0.167λ.

9. The SAW resonator device of claim 6, wherein, The thickness of the second metal layer ranges from 0.033λ to 0.16λ.

10. The SAW resonator device as claimed in claim 1, wherein, The material of the temperature compensation layer comprises silicon dioxide, silicon oxynitride, silicon oxycarbide or silicon oxyfluoride.

11. The SAW resonator device as claimed in claim 1, wherein, The material of the substrate comprises silicon, silicon carbide or diamond.

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

13. A filtering device, characterized by Comprising: the surface acoustic wave resonator device of any one of claims 1 to 12.

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