Surface acoustic wave resonator and surface acoustic wave filter

Abstract

The utility model belongs to the technical field of resonators, and discloses a surface acoustic wave resonator and a surface acoustic wave filter, the surface acoustic wave resonator comprises an interdigital transduction layer, the interdigital transduction layer comprises a first bus bar and a second bus bar, the first bus bar comprises a first interdigital electrode, the second bus bar comprises a second interdigital electrode, and the interdigital transduction layer comprises a second interdigital electrode. An intersection region of the first interdigital electrode and the second interdigital electrode forms a main excitation region; the interdigital transduction layer further comprises a third bus bar and a fourth bus bar, the third bus bar comprises a third interdigital electrode, and the fourth bus bar comprises a fourth interdigital electrode; a fifth interdigital electrode and a sixth interdigital electrode are respectively arranged on the first interdigital electrode and the second interdigital electrode in an extending manner, a first excitation region is formed in an intersection region of the third interdigital electrode and the fifth interdigital electrode, and a second excitation region is formed in an intersection region of the fourth interdigital electrode and the sixth interdigital electrode. According to the surface acoustic wave resonator, the secondary excitation area is arranged, so that the quality factor value of the surface acoustic wave resonator is improved.

Description

Technical Field

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

[0002] A surface acoustic wave (SAW) resonator is an electronic component based on the piezoelectric effect. Its basic structure achieves efficient conversion between electrical signals and SAW waves by fabricating periodic interdigitated electrodes on the surface of a piezoelectric material. This device boasts advantages such as a high quality factor, low loss, small size, and ease of mass production, making it widely used not only in radio frequency communications but also in sensor applications such as temperature sensors, biosensors, and stress sensors. However, during operation, the SAW waves excited by the interdigitated electrodes on the piezoelectric material surface not only generate the dominant wave mode but also inevitably produce unwanted transverse modes. These transverse modes generate stray responses, thereby reducing the quality factor of the SAW resonator.

[0003] Therefore, how to suppress the transverse waves generated when the surface acoustic wave resonator is working in order to improve its quality factor is a technical problem that urgently needs to be solved. Utility Model Content

[0004] This invention provides a surface acoustic wave resonator and a surface acoustic wave filter to solve the technical problem that existing surface acoustic wave resonators generate transverse waves during operation.

[0005] In a first aspect, this utility model provides a surface acoustic wave resonator, comprising:

[0006] piezoelectric substrate;

[0007] An interdigitated transducer layer is disposed above the piezoelectric substrate. The interdigitated transducer layer includes a first bus bar and a second bus bar disposed opposite to each other along a first direction. The first bus bar includes a first interdigitated electrode disposed along the first direction. The second bus bar includes a second interdigitated electrode disposed parallel to the first interdigitated electrode. The intersection region of the first interdigitated electrode and the second interdigitated electrode forms the main excitation region.

[0008] The interdigitated transducer layer further includes a third busbar and a fourth busbar, which are respectively intersected with the first busbar and the second busbar. The third busbar includes a third interdigitated electrode, and the fourth busbar includes a fourth interdigitated electrode arranged parallel to the third interdigitated electrode. A fifth interdigitated electrode and a sixth interdigitated electrode are respectively extended along a first direction on the first interdigitated electrode and the second interdigitated electrode. The intersection region of the third interdigitated electrode and the fifth interdigitated electrode forms a first excitation region, and the intersection region of the fourth interdigitated electrode and the sixth interdigitated electrode forms a second excitation region.

[0009] Furthermore, the surface acoustic wave resonator also includes a reflection structure, which includes a first reflection strip disposed between the first interdigital electrode and the fifth interdigital electrode, and a second reflection strip disposed between the second interdigital electrode and the sixth interdigital electrode; and the first reflection strip and the second reflection strip are symmetrically arranged along the center line of the first interdigital electrode and the second interdigital electrode in a second direction.

[0010] Furthermore, the reflective structure also includes a third reflective strip and a fourth reflective strip respectively disposed on the third interdigital electrode and the fourth interdigital electrode. The third reflective strip is disposed at the end away from the first interdigital electrode, and the fourth reflective strip is disposed at the end away from the second interdigital electrode. The third reflective strip and the fourth reflective strip are symmetrically disposed along the center line of the first interdigital electrode and the second interdigital electrode in the second direction.

[0011] Furthermore, the first busbar and the second busbar are apodization weighted structures, and the lengths of each finger of the first interdigital electrode and the second interdigital electrode are not equal.

[0012] Furthermore, the length of each finger strip of the first interdigital electrode and the second interdigital electrode decreases from the center to both sides.

[0013] Furthermore, the first and second reflective strips have the same width, and the third and fourth reflective strips have the same width.

[0014] Furthermore, the reflective structure is disposed on the upper surface of the interdigitated transducer layer; or,

[0015] The upper surface of the piezoelectric substrate is etched with grooves, and the reflective structure is deposited in the grooves of the piezoelectric substrate.

[0016] Furthermore, the surface acoustic wave resonator also includes a reflective grating located on both sides of the interdigital transducer layer, the reflective grating comprising a plurality of periodically arranged fifth reflective strips.

[0017] Furthermore, the thickness of the piezoelectric substrate is 0.3mm-0.7mm, the thickness of the interdigital transducer layer is 50nm-300nm, and the thickness of the reflective structure is 100nm-1000nm.

[0018] In a second aspect, the present invention provides a surface acoustic wave filter, the surface acoustic wave filter comprising a surface acoustic wave resonator as described in any one of the first aspects.

[0019] Compared with the prior art, the surface acoustic wave resonator provided by this utility model effectively limits the propagation range of surface acoustic waves and suppresses the scattering phenomenon of surface acoustic waves by setting a reflection structure on the interdigital electrodes of the busbar. Furthermore, the secondary excitation region set on the interdigital transducer layer enhances the excitation intensity of surface acoustic waves, improves the excitation energy of the resonator, and further improves the quality factor of the surface acoustic wave resonator. Attached Figure Description

[0020] Figure 1 A schematic diagram of the structure of a surface acoustic wave resonator provided in an embodiment of this utility model;

[0021] Figure 2 Another structural schematic diagram of a surface acoustic wave resonator provided in an embodiment of this utility model;

[0022] Figure 3 A cross-sectional schematic diagram of a reflective structure provided in an embodiment of this utility model;

[0023] Figure 4 A cross-sectional schematic diagram of another reflective structure provided in an embodiment of this utility model;

[0024] Figure 5 This is a schematic diagram of the shape of another reflective structure provided in an embodiment of the present invention.

[0025] In this structure, 10 is a piezoelectric substrate, 20 is an interdigital transducer layer, 21 is a first busbar, 211 is a first interdigital electrode, 212 is a fifth interdigital electrode, 22 is a second busbar, 221 is a second interdigital electrode, 222 is a sixth interdigital electrode, 23 is a third busbar, 231 is a third interdigital electrode, 24 is a fourth busbar, 241 is a fourth interdigital electrode, 25 is the main excitation region, 26 is the first excitation region, 27 is the second excitation region, 30 is a reflection structure, 31 is a first reflection bar, 32 is a second reflection bar, 33 is a third reflection bar, 34 is a fourth reflection bar, 40 is a reflection grating, and 41 is a fifth reflection bar. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the scope of the present utility model.

[0027] To make the description of this disclosure more detailed and complete, illustrative descriptions of the embodiments and specific examples of this utility model are provided below; however, this is not the only form of implementing or using the specific embodiments of this utility model. The embodiments cover the features of multiple specific embodiments and the methods, steps, and their order for constructing and operating these specific embodiments. However, other specific embodiments can also be used to achieve the same or equivalent functions and step sequences. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0028] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this utility model are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this utility model described herein can be implemented in sequences other than those illustrated or described herein.

[0029] In the description of the embodiments of this utility model, unless otherwise stated, " / " means "or". For example, A / B can mean A or B. The word "and / or" in the text is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone. In addition, in the description of the embodiments of this application, "multiple" means two or more. Other quantifiers should be understood similarly. The preferred embodiments described herein are only used to illustrate and explain this utility model and are not intended to limit this utility model. Furthermore, the embodiments and features in the embodiments of this application can be combined with each other without conflict.

[0030] To address the technical problem of existing surface acoustic wave (SAW) resonators generating transverse waves during operation, this invention provides a SAW resonator. Please refer to [reference needed]. Figure 1 , Figure 1This is a schematic diagram of a surface acoustic wave (SAW) resonator provided in an embodiment of the present invention. The SAW resonator includes a piezoelectric substrate 10; an interdigital transducer layer 20 is disposed above the piezoelectric substrate 10, the interdigital transducer layer 20 includes a first busbar 21 and a second busbar 22 disposed opposite to each other along a first direction, the first busbar 21 includes a first interdigital electrode 211 disposed along the first direction, and the second busbar 22 includes a second interdigital electrode 221 disposed parallel to the first interdigital electrode 211, the intersection region of the first interdigital electrode 211 and the second interdigital electrode 221 forms a main excitation region 25; the interdigital transducer layer 20 also includes components respectively disposed with respect to the first interdigital electrode 211 and the second interdigital electrode 221. A third busbar 23 and a fourth busbar 24 are intersected by busbar 21 and the second busbar 22. The third busbar 23 includes a third interdigital electrode 231, and the fourth busbar 24 includes a fourth interdigital electrode 241 arranged parallel to the third interdigital electrode 231. A fifth interdigital electrode 212 and a sixth interdigital electrode 222 are respectively extended along a first direction on the first interdigital electrode 211 and the second interdigital electrode 221. The intersection region of the third interdigital electrode 231 and the fifth interdigital electrode 212 forms a first excitation region 26, and the intersection region of the fourth interdigital electrode 241 and the sixth interdigital electrode 222 forms a second excitation region 27. Specifically, in this embodiment of the invention, by setting the first excitation region 26 and the second excitation region 27 in the interdigital transducer layer, the excitation intensity of the surface acoustic wave is effectively enhanced, the excitation energy of the surface acoustic wave resonator is improved, and the quality factor of the surface acoustic wave resonator is further improved.

[0031] As a further preferred option, please refer to Figure 2 , Figure 2 This is another schematic diagram of a surface acoustic wave (SAW) resonator provided in an embodiment of the present invention. The SAW resonator further includes a reflection structure 30, which includes a first reflection strip 31 disposed between the first interdigital electrode 211 and the fifth interdigital electrode 212, and a second reflection strip 32 disposed between the second interdigital electrode 221 and the sixth interdigital electrode 222. The first reflection strip 31 and the second reflection strip 32 are symmetrically arranged along the centerline of the first interdigital electrode 211 and the second interdigital electrode 221 in a second direction. Specifically, in this embodiment of the present invention, by providing the first reflection strip 31 and the second reflection strip 32 in the SAW resonator, the propagating acoustic wave energy can be effectively reflected back to the main excitation region, effectively improving the utilization rate of SAW energy, reducing energy loss, and thus improving the overall performance of the SAW resonator. Furthermore, symmetrically arranging the first reflection strip 31 and the second reflection strip 32 along the centerline of the first interdigital electrode 211 and the second interdigital electrode 221 in a second direction ensures a uniform distribution of SAW waves, thereby effectively improving the selectivity and stability of the resonator frequency.

[0032] As a further preferred option, please refer to Figure 2 The reflection structure 30 further includes a third reflection strip 33 and a fourth reflection strip 34 respectively disposed on the third interdigital electrode 231 and the fourth interdigital electrode 241. The third reflection strip 33 is disposed at the end away from the first interdigital electrode 211, and the fourth reflection strip 34 is disposed at the end away from the second interdigital electrode 221. The third reflection strip 33 and the fourth reflection strip 34 are symmetrically arranged along the center line of the first interdigital electrode 211 and the second interdigital electrode 221 in the second direction. Specifically, in this embodiment of the invention, by providing the third reflection strip 33 and the fourth reflection strip 34 in the surface acoustic wave resonator and disposing of them on the third interdigital electrode 231 and the fourth interdigital electrode 241 respectively, the propagating acoustic wave energy can be effectively reflected back to the first excitation region 26 and the second excitation region 27, further reducing the energy loss of the surface acoustic wave.

[0033] As a further preferred option, please refer to Figure 1 The first busbar 21 and the second busbar 22 are apodization weighted structures, and the lengths of the fingers of the first interdigital electrode 211 and the second interdigital electrode 221 are not equal. Specifically, in this embodiment of the invention, the first busbar 21 and the second busbar 22 can be configured as apodization weighted structures. The specific apodization weighting function is not further limited and can be a cosine function, a Gaussian function, or other apodization weighting functions, depending on actual needs. The lengths of the fingers of the first interdigital electrode 211 and the second interdigital electrode 221 are not equal. By setting the first interdigital electrode 211 and the second interdigital electrode 221 to unequal lengths, the interdigital electrodes of unequal lengths have different corresponding characteristics for surface acoustic waves of different frequencies, effectively widening the operating bandwidth of the surface acoustic wave resonator. Furthermore, the third bus bar 23 and the fourth bus bar 24 are also apodization weighted structures, the lengths of each finger bar of the third interdigital electrode 231 and the fourth interdigital electrode 241 are not equal, and the lengths of each finger bar of the fifth interdigital electrode 212 and the sixth interdigital electrode 222 are not equal.

[0034] As a further preferred option, please refer to Figure 1 The lengths of the fingers of the first interdigital electrode 211 and the second interdigital electrode 221 decrease from the center to both sides. Specifically, in this embodiment of the invention, by designing the first interdigital electrode 211 and the second interdigital electrode 221 to be of unequal length, the electrodes can have different response characteristics to surface acoustic waves of different frequencies.

[0035] As a further preferred option, please refer to Figure 2The first reflective strip 31 and the second reflective strip 32 have the same width, and the third reflective strip 33 and the fourth reflective strip 34 have the same width. Specifically, in this embodiment of the invention, by setting the first reflective strip 31 and the second reflective strip 32 to have the same width, and setting the third reflective strip 33 and the fourth reflective strip 34 to have the same width, the consistency and symmetry of surface acoustic wave reflection are improved.

[0036] As a further preferred option, please refer to Figures 3-4 , Figure 3 This is a cross-sectional schematic diagram of a reflective structure provided in an embodiment of the present invention. Figure 4 This is a cross-sectional schematic diagram of another reflective structure provided in an embodiment of the present invention. The reflective structure 30 is disposed on the upper surface of the interdigital transducer layer 20; or, a groove 11 is etched on the upper surface of the piezoelectric substrate 10, and the reflective structure 30 is deposited in the groove 11 of the piezoelectric substrate 10. Specifically, in this embodiment of the present invention, the reflective structure 30 is disposed on the upper or lower surface of the interdigital transducer layer 20, which can be flexibly selected according to the application scenario and process requirements. When disposed on the upper surface of the interdigital transducer layer 20, please refer to... Figure 3 A reflective structure 30 can be disposed on the upper surface of the interdigital transducer layer 20; when disposed on the lower surface of the interdigital transducer layer 20, please refer to... Figure 4 A groove 11 can be etched on the upper surface of the piezoelectric substrate 10, and a reflective structure 30 is deposited in the groove 11 of the piezoelectric substrate 10.

[0037] As a further preferred option, please refer to Figure 2 and Figure 5 , Figure 5 This is a schematic diagram of another reflective structure provided in an embodiment of the present invention. In this embodiment, the specific shape of the reflective structure 30 is not further limited, and can be a straight line, a broken line, or a curve, etc. Figure 2 In the middle, the specific shape of the first reflective strip 31 and the second reflective strip 32 is a broken line, such as... Figure 5 In the middle, the specific shapes of the first reflective strip 31 and the second reflective strip 32 are straight lines, which can be set according to actual needs.

[0038] As a further preferred option, please refer to Figure 1 The surface acoustic wave resonator further includes a reflective grating 40, which is located on both sides of the interdigital transducer layer 20. The reflective grating 40 includes a plurality of periodically arranged fifth reflective strips 41. Specifically, in this embodiment of the invention, the reflective grating 40 effectively limits the propagation range of the surface acoustic wave, reduces the energy leakage of the surface acoustic wave, and improves the energy concentration of the dominant mode of the surface acoustic wave.

[0039] As a further preferred embodiment, the thickness of the piezoelectric substrate 10 is 0.3mm-0.7mm. Specifically, in this embodiment of the present invention, a thinner piezoelectric substrate can improve the speed and efficiency of surface acoustic waves, while a thicker substrate enhances the overall stability of the surface acoustic wave resonator. Setting the thickness of the piezoelectric substrate 10 to 0.3mm-0.7mm ensures that the piezoelectric substrate 10 can provide sufficient mechanical strength to support the entire device, effectively propagate surface acoustic waves, and reduce energy loss.

[0040] As a further preferred embodiment, the thickness of the interdigital transducer layer 20 is 50nm-300nm. This thickness range ensures that the interdigital transducer layer 20 can efficiently convert electrical signals into surface acoustic waves, while also avoiding energy loss caused by excessive thickness and manufacturing difficulties caused by excessive thinness.

[0041] As a further preferred embodiment, the thickness of the reflective structure 30 is 100nm-1000nm. This thickness range enables the reflective structure to effectively reflect surface acoustic waves while maintaining good matching with the interdigital transducer layer 20, thereby improving reflection efficiency and reducing energy loss.

[0042] As a further preferred option, the material in the interdigitated transducer layer 20 is selected from one or more of Al, Au, Pt, Cu, Ag, W, Ti, Cr, Mo, In, Zn, Zr or Pd.

[0043] As a further preferred option, the material of the reflective structure is an alloy composed of Al, Au, Pt, Cu, Ag, W, Ti, Cr, Mo, In, Zn, Zr or Pd, or a dielectric material such as SiO2, SiN, AlN, Al2O3.

[0044] Secondly, this utility model also provides a surface acoustic wave filter, which includes a surface acoustic wave resonator as described in the first aspect above.

[0045] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0046] The above embodiments only illustrate preferred implementations of this utility model, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A surface acoustic wave resonator, characterized in that, include: piezoelectric substrate; An interdigitated transducer layer is disposed above the piezoelectric substrate. The interdigitated transducer layer includes a first bus bar and a second bus bar disposed opposite to each other along a first direction. The first bus bar includes a first interdigitated electrode disposed along the first direction. The second bus bar includes a second interdigitated electrode disposed parallel to the first interdigitated electrode. The intersection region of the first interdigitated electrode and the second interdigitated electrode forms the main excitation region. The interdigitated transducer layer further includes a third busbar and a fourth busbar, which are respectively intersected with the first busbar and the second busbar. The third busbar includes a third interdigitated electrode, and the fourth busbar includes a fourth interdigitated electrode arranged parallel to the third interdigitated electrode. A fifth interdigitated electrode and a sixth interdigitated electrode are respectively extended along a first direction on the first interdigitated electrode and the second interdigitated electrode. The intersection region of the third interdigitated electrode and the fifth interdigitated electrode forms a first excitation region, and the intersection region of the fourth interdigitated electrode and the sixth interdigitated electrode forms a second excitation region.

2. The surface acoustic wave resonator according to claim 1, characterized in that, The surface acoustic wave resonator further includes a reflection structure, which includes a first reflection strip disposed between the first interdigital electrode and the fifth interdigital electrode, and a second reflection strip disposed between the second interdigital electrode and the sixth interdigital electrode; and the first reflection strip and the second reflection strip are symmetrically arranged along the center line of the first interdigital electrode and the second interdigital electrode in a second direction.

3. The surface acoustic wave resonator according to claim 2, characterized in that, The reflective structure further includes a third reflective strip and a fourth reflective strip respectively disposed on the third interdigital electrode and the fourth interdigital electrode. The third reflective strip is disposed at the end away from the first interdigital electrode, and the fourth reflective strip is disposed at the end away from the second interdigital electrode. The third reflective strip and the fourth reflective strip are symmetrically disposed along the center line of the first interdigital electrode and the second interdigital electrode in the second direction.

4. The surface acoustic wave resonator according to claim 1, characterized in that, The first busbar and the second busbar are apodization weighted structures, and the lengths of each finger of the first interdigital electrode and the second interdigital electrode are not equal.

5. The surface acoustic wave resonator according to claim 4, characterized in that, The length of each finger strip of the first and second interdigital electrodes decreases from the center to both sides.

6. The surface acoustic wave resonator according to claim 3, characterized in that, The first and second reflective strips have the same width, and the third and fourth reflective strips have the same width.

7. The surface acoustic wave resonator according to claim 2, characterized in that, The reflective structure is disposed on the upper surface of the interdigitated transducer layer; or, The upper surface of the piezoelectric substrate is etched with grooves, and the reflective structure is deposited in the grooves of the piezoelectric substrate.

8. The surface acoustic wave resonator according to claim 1, characterized in that, The surface acoustic wave resonator also includes a reflective grating located on both sides of the interdigital transducer layer, the reflective grating comprising a plurality of periodically arranged fifth reflective strips.

9. The surface acoustic wave resonator according to claim 2, characterized in that, The thickness of the piezoelectric substrate is 0.3mm-0.7mm, the thickness of the interdigital transducer layer is 50nm-300nm, and the thickness of the reflective structure is 100nm-1000nm.

10. A surface acoustic wave filter, characterized in that, The surface acoustic wave filter includes a surface acoustic wave resonator as described in any one of claims 1-9.

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