Surface acoustic wave resonator

Abstract

The invention discloses a surface acoustic wave resonator, which is characterized in that an interdigital electrode of the surface acoustic wave resonator is step-shaped, and the interdigital electrode has various heights on the surface of one side close to a substrate, or the interdigital electrode has various position differences in a first direction; the surfaces, close to one side of the substrate, of the first bus bar and the second bus bar have the same first height, and the height, on the surface, close to one side of the substrate, of a first step area, at least connected with the first bus bar or the second bus bar, of the interdigital electrode is equal to the first height. A height of another region not connected to the first bus bar or the second bus bar is less than or equal to the first height. According to the invention, by changing the acoustic impedance boundary condition of the resonance area, the pseudo mode of the resonator can be suppressed, the transverse leakage of sound waves near the anchor point can be reduced, the sound waves are only concentrated in the middle area, and a better quality factor improvement effect can be obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of resonators, and particularly to a surface acoustic wave resonator. Background Art

[0002] Surface acoustic wave resonators are widely used in radio frequency resonators and have been widely applied in fields such as wireless communication, sensors, and signal processing. At present, surface acoustic wave resonator technology still faces some deficiencies, especially in terms of spurious mode suppression and quality factor improvement.

[0003] Spurious modes refer to non-rational modes caused by factors such as device structure or material defects near the operating frequency of the surface acoustic wave resonator. These spurious modes usually lead to signal distortion and reduce the performance of the device. Current surface acoustic wave resonators have certain difficulties in suppressing spurious modes. Especially for high-frequency or narrow-band applications, the influence of spurious modes is particularly significant. However, in practical applications, completely suppressing spurious modes remains a challenge. Therefore, a more efficient spurious mode suppression strategy is needed to ensure the stability and frequency selectivity of the resonator.

[0004] The quality factor is an important parameter for measuring the performance of a resonator, which represents the degree of energy loss of the resonator. A high Q value means low energy loss and higher frequency selectivity, which are key requirements in many high-frequency applications. However, current technology faces some bottlenecks in improving the quality of surface acoustic wave resonators. Although the Q value can be improved to a certain extent by optimizing materials (low-loss piezoelectric materials), reducing electrode loss, and improving structural design, due to factors such as surface effects, mechanical mismatch, and interface loss between the electrode and the material, the improvement of the Q value is still limited. In addition, as the operating frequency increases, it becomes more difficult to improve the Q value because the device size and structural complexity in the high-frequency case also affect the performance of the loss. Summary of the Invention

[0005] The present invention provides a surface acoustic wave resonator that can suppress spurious modes and improve the quality factor.

[0006] An embodiment of the present invention provides a surface acoustic wave resonator, including: a substrate and an electrode layer located on one side of the substrate;

[0007] The electrode layer includes a first bus bar and a second bus bar arranged in parallel along a first direction, and a plurality of interdigital electrodes that are alternately arranged and connected to the first bus bar or the second bus bar and are arranged in parallel along a second direction;

[0008] The shape of the interdigital electrode is stepped, and the surface of the interdigital electrode on the side close to the substrate has multiple heights, or the interdigital electrode has multiple position differences in the first direction; wherein, the first direction and the second direction are perpendicular to each other; the first bus bar and the second bus bar have the same first height on the surface on the side close to the substrate, and the height of the first stepped area where the interdigital electrode is at least connected to the first bus bar or the second bus bar on the surface on the side close to the substrate is equal to the first height; the height of other areas of the interdigital electrode not connected to the first bus bar or the second bus bar is less than or equal to the first height.

[0009] Optionally, the interdigital electrode further includes m stepped areas connected in sequence along the second direction; wherein, m>2 and m is a positive integer;

[0010] On the surface on the side close to the substrate, the interdigital electrode has n height gradients, and there is at least one concave portion in the interdigital electrode; wherein, n≥2 and n is a positive integer.

[0011] Optionally, the interdigital electrode further includes a second stepped area, a third stepped area, a fourth stepped area, a fifth stepped area, a sixth stepped area, a seventh stepped area, an eighth stepped area, and a ninth stepped area connected in sequence along the second direction; the second stepped area is connected to the first stepped area;

[0012] On the surface on the side close to the substrate, the heights of the first stepped area and the ninth stepped area are both in the first height gradient, the heights of the second stepped area and the eighth stepped area are both in the second height gradient, the heights of the third stepped area and the seventh stepped area are both in the third height gradient, the heights of the fourth stepped area and the sixth stepped area are both in the fourth height gradient, and the height of the fifth stepped area is in the fifth height gradient;

[0013] The first height gradient is greater than the second height gradient, the second height gradient is greater than the third height gradient, the third height gradient is greater than the fourth height gradient, the fourth height gradient is greater than the fifth height gradient; the fifth height gradient is greater than 0; wherein the heights in the first height gradient are all equal to the first height.

[0014] Optionally, the interdigital electrode further includes a second stepped area, a third stepped area, a fourth stepped area, a fifth stepped area, a sixth stepped area, a seventh stepped area, an eighth stepped area, and a ninth stepped area connected in sequence along the second direction; the second stepped area is connected to the first stepped area;

[0015] On the surface closer to the substrate side, the heights of the first step region, the fifth step region, and the ninth step region are all at the sixth height gradient, the heights of the second step region, the fourth step region, the sixth step region, and the eighth step region are all at the seventh height gradient, and the heights of the third step region and the seventh step region are all at the eighth height gradient;

[0016] The sixth height gradient is greater than the seventh height gradient, and the seventh height gradient is greater than the eighth height gradient; the heights in the eighth height gradient are all greater than 0, and the heights in the sixth height gradient are all equal to the first height.

[0017] Optionally, the interdigital electrode further includes a second step region, a third step region, a fourth step region, a fifth step region, a sixth step region, a seventh step region, an eighth step region, and a ninth step region connected in sequence along the second direction; the second step region is connected to the first step region;

[0018] On the surface closer to the substrate side, the heights of the first step region, the third step region, the fifth step region, the seventh step region, and the ninth step region are all at the eighth height gradient, and the heights of the second step region, the fourth step region, the sixth step region, and the eighth step region are all at the ninth height gradient;

[0019] The eighth height gradient is greater than the ninth height gradient, the heights in the ninth height gradient are all greater than 0 and less than or equal to two-thirds of the first height, and the heights in the eighth height gradient are all equal to the first height.

[0020] Optionally, on the surface closer to the substrate side, the interdigital electrode includes multiple heights located within multiple height gradients and decreasing in sequence along the second direction.

[0021] Optionally, on the surface closer to the substrate side, the height of the interdigital electrode is equal to the first height; in the first direction, the interdigital electrode includes multiple step regions, and there is a positional difference between each step region.

[0022] Optionally, the electrode layer further includes dummy fingers having the same number as the interdigital electrodes;

[0023] The dummy fingers are disposed opposite to the interdigital electrodes, and there is a first distance between the side of the dummy fingers closer to the interdigital electrodes and the side of the interdigital electrodes closer to the dummy fingers;

[0024] The first distance is less than or equal to twice the wavelength of the acoustic wave of the surface acoustic wave resonator.

[0025] Optionally, the shape of the dummy finger is a stepped shape, and the dummy finger includes at least two stepped regions connected in sequence along the second direction;

[0026] The height of the stepped region connected to the first bus bar or the second bus bar is equal to the first height, and the heights of the remaining stepped regions not connected to the first bus bar or the second bus bar are all less than or equal to the first height.

[0027] Optionally, the surface of the interdigital electrode on the side close to the substrate has at least two heights.

[0028] An embodiment of the present invention provides a surface acoustic wave resonator, including: a substrate and an electrode layer located on one side of the substrate; the electrode layer includes a first bus bar and a second bus bar arranged in parallel along a first direction, and a plurality of interdigital electrodes alternately arranged and connected to the first bus bar or the second bus bar and arranged in parallel along a second direction; the shape of the interdigital electrode is a stepped shape, and the surface of the interdigital electrode on the side close to the substrate has multiple heights, or the interdigital electrode has multiple position differences in the first direction; wherein, the first direction and the second direction are perpendicular to each other; the first bus bar and the second bus bar have the same first height on the surface close to the substrate, and the second height of the first stepped region where the interdigital electrode is at least connected to the first bus bar or the second bus bar on the surface close to the substrate is equal to the first height. The present invention changes the acoustic impedance boundary conditions in the resonant region by preparing a stepped-shaped interdigital electrode and setting that the surface of the interdigital electrode on the side close to the substrate has multiple heights, or the interdigital electrode has multiple position differences in the first direction, so as to be able to suppress the pseudo-mode of the resonator, and at the same time can reduce the lateral leakage of the acoustic wave near the anchor point and only concentrate in the middle region, and a better quality factor improvement effect can be obtained.

[0029] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. Description of the Drawings

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0031] Figure 1 It is a partial structural schematic diagram of a surface acoustic wave resonator provided by an embodiment of the present invention;

[0032] Figure 2 is Figure 1Cross-sectional view of the surface acoustic wave resonator along AA';

[0033] Figure 3 Partial structural schematic diagram of another surface acoustic wave resonator provided by an embodiment of the present invention;

[0034] Figure 4 Top view of a surface acoustic wave resonator provided by an embodiment of the present invention;

[0035] Figure 5 Simulation schematic diagram of a surface acoustic wave resonator of the prior art provided by an embodiment of the present invention;

[0036] Figure 6 Simulation schematic diagram of a surface acoustic wave resonator provided by an embodiment of the present invention;

[0037] Figure 7 Partial sectional view of another surface acoustic wave resonator provided by an embodiment of the present invention;

[0038] Figure 8 Partial sectional view of another surface acoustic wave resonator provided by an embodiment of the present invention;

[0039] Figure 9 Partial sectional view of another surface acoustic wave resonator provided by an embodiment of the present invention;

[0040] Figure 10 Partial structural schematic diagram of another surface acoustic wave resonator provided by an embodiment of the present invention;

[0041] Figure 11 is Figure 10 Cross-sectional view of the surface acoustic wave resonator along BB';

[0042] Figure 12 Simulation quality factor improvement diagram provided by an embodiment of the present invention;

[0043] Figure 13 Partial structural schematic diagram of another surface acoustic wave resonator provided by an embodiment of the present invention;

[0044] Figure 14 is Figure 13 Cross-sectional view of the surface acoustic wave resonator along CC'. Detailed implementation manners

[0045] To enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

[0046] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily need to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0047] Figure 1 It is a partial structural schematic diagram of a surface acoustic wave resonator provided by an embodiment of the present invention. Figure 2 is Figure 1 a sectional view of the surface acoustic wave resonator in along AA'. Figure 3 It is a partial structural schematic diagram of another surface acoustic wave resonator provided by an embodiment of the present invention. Figure 4 It is a top view of a surface acoustic wave resonator provided by an embodiment of the present invention ( Figure 1 and Figure 3 the substrate is not shown), referring to Figure 1-4 , the surface acoustic wave resonator includes: a substrate 100 and an electrode layer 200 located on one side of the substrate. The electrode layer 200 includes a first bus bar 210 and a second bus bar 220 arranged in parallel along the first direction x, and a plurality of interdigital electrodes 230 alternately arranged and connected to the first bus bar 210 or the second bus bar 220 and arranged in parallel along the second direction y. The shape of the interdigital electrode 230 is a stepped shape, and the surface of the interdigital electrode 230 on the side close to the substrate 100 has multiple heights (refer to Figure 1 and Figure 2 ), or the interdigital electrode 230 has multiple position differences in the first direction x (refer to Figure 3 and Figure 4); wherein, the first direction x and the second direction y are perpendicular to each other; the first bus bar 210 and the second bus bar 220 have the same first height on the surface close to the substrate 100 side, and the height of the first step region 231 where the interdigital electrode 230 is at least connected to the first bus bar 210 or the second bus bar 220 on the surface close to the substrate 100 side is equal to the first height, and the height of other regions of the interdigital electrode 230 not connected to the first bus bar 210 or the second bus bar 220 is less than or equal to the first height.

[0048] It can be understood that the shape of the interdigital electrode 230 is stepped, and the interdigital electrode 230 has multiple heights on the surface close to the substrate 100 side, or the interdigital electrode 230 has multiple position differences in the first direction x, which can change the acoustic impedance boundary condition of the resonant region. The height of the first step region 231 where the interdigital electrode 230 is at least connected to the first bus bar 210 or the second bus bar 220 on the surface close to the substrate 100 side is equal to the first height, and the height of other regions of the interdigital electrode 230 not connected to the first bus bar 210 or the second bus bar 220 being less than or equal to the first height can make the height of the middle region of the interdigital electrode 230 less than or equal to the height of the edge region, so as to achieve the effect of reducing the anchor loss and improving the quality factor.

[0049] It should be noted that the quality factor is directly related to the loss of the acoustic wave signal excited by the device. In a resonant device, the loss mainly includes anchor loss and substrate loss. In view of the deficiencies of the prior art, the present invention prepares the shape of the interdigital electrode 230 as stepped, and the interdigital electrode 230 has multiple heights on the surface close to the substrate 100 side, or the interdigital electrode 230 has multiple position differences in the first direction x, which can change the acoustic impedance boundary condition of the resonant region and suppress the pseudo-mode of the resonator. The principle of the solution of the embodiment of the present invention is to set an acoustic impedance boundary on the acoustic wave propagation path, and improve the quality factor by reducing the anchor loss. By analogy, it is like setting a speed bump during the driving of a car. When multiple stepped acoustic impedance boundaries are set, it is equivalent to setting up layers of speed bumps, so that the lateral leakage of the acoustic wave near the anchor point is reduced and only concentrated in the middle region, so as to obtain a better effect of improving the quality factor.

[0050] Optionally, on the basis of the above embodiment, the interdigital electrode 230 further includes m step regions connected in sequence along the second direction y; wherein, m>2, and m is a positive integer; on the surface close to the substrate 100 side, the interdigital electrode 230 has n height gradients, and there is at least one concave of the interdigital electrode 230; wherein, n≥2, and n is a positive integer.

[0051] It should be noted that the number of step regions, the height gradient of the interdigital electrode 230, and the concavity of the interdigital electrode 230 can be arbitrarily set on the basis of meeting the limiting conditions and preparation conditions of the embodiments of the present invention.

[0052] Optionally, in one embodiment, continue to refer to Figure 1 and Figure 2 , the interdigital electrode 230 further includes a second step region 232, a third step region 233, a fourth step region 234, a fifth step region 235, a sixth step region 236, a seventh step region 237, an eighth step region 238, and a ninth step region 239 that are connected in sequence along the second direction y; the second step region 232 is connected to the first step region 231; on the surface closer to the substrate 100, the height h1 of the first step region 231 and the height h9 of the ninth step region 239 are both located in the first height gradient, the height h2 of the second step region 232 and the height h8 of the eighth step region 238 are both located in the second height gradient, the height h3 of the third step region 233 and the height h7 of the seventh step region 237 are both located in the third height gradient, the height h4 of the fourth step region 234 and the height h6 of the sixth step region 236 are both located in the fourth height gradient, and the height h5 of the fifth step region 235 is located in the fifth height gradient; the first height gradient is greater than the second height gradient, the second height gradient is greater than the third height gradient, the third height gradient is greater than the fourth height gradient, and the fourth height gradient is greater than the fifth height gradient; the fifth height gradient is greater than 0; wherein the heights in the first height gradient are all equal to the first height.

[0053] It should be noted that in the embodiments of the present invention, the heights in the first height gradient are all equal to the first height, and the heights of the step regions within the same height gradient are not necessarily the same, and the heights in each height gradient are greater than 0. The solution of the embodiments of the present invention makes the interdigital electrode have a concave.

[0054] Figure 5 is a simulation schematic diagram of a surface acoustic wave resonator of the prior art provided by the embodiments of the present invention, Figure 5 specifically, it is the simulation result that the interdigital electrode of the surface acoustic wave resonator of the prior art only has one height on the surface closer to the substrate. Figure 6 is a simulation schematic diagram of a surface acoustic wave resonator provided by the embodiments of the present invention, Figure 6 specifically, it is the simulation result of the interdigital electrode of the surface acoustic wave resonator provided by the embodiments of the present invention having five height gradients and two equal heights within the same gradient for simulation. Refer to Figure 5 and Figure 6 it can be seen that Figure 5 there are many pseudo-modes near the main mode of the surface impedance curve in , which will affect the device performance in actual applications. Figure 6The corresponding surface acoustic wave resonator can significantly suppress the pseudo-mode, ensuring a smooth resonance response. At the same time, this decreasing gradient distribution will increase the resonance frequency, which is beneficial for high-frequency applications.

[0055] Figure 7 This is a partial region cross-sectional view of another surface acoustic wave resonator provided by an embodiment of the present invention. Optionally, in one embodiment, referring to Figure 7 , the interdigital electrode 230 further includes a second step region 232, a third step region 233, a fourth step region 234, a fifth step region 235, a sixth step region 236, a seventh step region 237, an eighth step region 238, and a ninth step region 239 that are sequentially connected along the second direction y; the second step region 232 is connected to the first step region 231; on the surface closer to the substrate 100, the height h1 of the first step region 231, the height h5 of the fifth step region 235, and the height h9 of the ninth step region 239 are all located at the sixth height gradient, the height h2 of the second step region 232, the height h4 of the fourth step region 234, the height h6 of the sixth step region 236, and the height h8 of the eighth step region 238 are all located at the seventh height gradient, and the height h3 of the third step region 233 and the height h7 of the seventh step region 237 are both located at the eighth height gradient; the sixth height gradient is greater than the seventh height gradient, and the seventh height gradient is greater than the eighth height gradient; the heights in the eighth height gradient are all greater than 0, and the heights in the sixth height gradient are all equal to the first height.

[0056] It should be noted that in the embodiment of the present invention, the heights in the sixth height gradient are all equal to the first height, and the height sizes of the step regions within the same height gradient are not necessarily the same, and the heights in each height gradient are all greater than 0. The solution of the embodiment of the present invention makes the interdigital electrode have two depressions.

[0057] Figure 8 This is a partial region cross-sectional view of another surface acoustic wave resonator provided by an embodiment of the present invention. Optionally, in one embodiment, referring to Figure 8, the interdigital electrode 230 further includes a second stepped region 232, a third stepped region 233, a fourth stepped region 234, a fifth stepped region 235, a sixth stepped region 236, a seventh stepped region 237, an eighth stepped region 238, and a ninth stepped region 239 that are connected in sequence along the second direction y; the second stepped region 232 is connected to the first stepped region 231; on the surface closer to the substrate 100, the height h1 of the first stepped region 231, the height h3 of the third stepped region 233, the height h5 of the fifth stepped region 235, the height h7 of the seventh stepped region 237, and the height h9 of the ninth stepped region 239 are all located at the eighth height gradient, and the height h2 of the second stepped region 232, the height h4 of the fourth stepped region 234, the height h6 of the sixth stepped region 236, and the height h8 of the eighth stepped region 238 are all located at the ninth height gradient; the eighth height gradient is greater than the ninth height gradient, the heights in the ninth height gradient are all greater than 0 and less than or equal to two-thirds of the first height, and the heights in the eighth height gradient are all equal to the first height.

[0058] It should be noted that in the embodiment of the present invention, the heights of the eighth height gradient are all equal to the first height, and the heights of the stepped regions within the same height gradient are not necessarily the same, and the heights in each height gradient are all greater than 0. The solution of the embodiment of the present invention makes the interdigital electrode have four depressions.

[0059] Figure 9 It is a partial region cross-sectional view of another surface acoustic wave resonator provided by an embodiment of the present invention. Optionally, in one embodiment, refer to Figure 9 , on the surface closer to the substrate 100, the interdigital electrode 230 includes multiple heights located at multiple height gradients and decreasing in sequence along the second direction y.

[0060] It should be noted that considering the manufacturing process, the present invention does not set many thickness gradients. The solution of the embodiment of the present invention includes but is not limited to Figure 9 the nine heights shown decreasing in sequence.

[0061] Optionally, on the basis of the above embodiment, continue to refer to Figure 3 and Figure 4 , on the surface closer to the substrate 100, the height of the interdigital electrode 230 is equal to the first height; in the first direction x, the interdigital electrode 230 includes multiple stepped regions, and there is a position difference between each stepped region.

[0062] In the embodiment of the present invention, on the surface closer to the substrate 100, the height of the interdigital electrode 230 is equal to the first height. In the first direction x, the interdigital electrode 230 includes multiple stepped regions, and there is a position difference between each stepped region, which can simultaneously establish different acoustic impedance boundaries and acoustic reflection boundaries, and set multiple acoustic reflection boundaries in the acoustic wave transmission path, so as to achieve the effect of suppressing pseudo-modes and improving the quality factor.

[0063] Figure 10 Partial structural schematic diagram of another surface acoustic wave resonator provided by an embodiment of the present invention ( Figure 10 The substrate 100 is not shown in Figure 11 is Figure 10 Cross-sectional view of the surface acoustic wave resonator in along BB'. Optionally, on the basis of the above embodiment, refer to Figure 10 and Figure 11 , the electrode layer 200 further includes dummy fingers 240 having the same number as the interdigital electrodes 230; the dummy fingers 240 are disposed opposite to the interdigital electrodes 230, and there is a first distance between the side of the dummy fingers 240 close to the interdigital electrodes 230 and the side of the interdigital electrodes 230 close to the dummy fingers 240; the first distance is less than or equal to twice the wavelength of the acoustic wave of the surface acoustic wave resonator.

[0064] In the embodiment of the present invention, by adding the dummy fingers 240 on the basis of the above embodiment, the acoustic reflection boundary is increased, so that the acoustic wave is concentrated in the central resonance region, and the quality factor is improved. There is a first distance between the side of the dummy fingers 240 close to the interdigital electrodes 230 and the side of the interdigital electrodes 230 close to the dummy fingers 240; the first distance is less than or equal to twice the wavelength of the acoustic wave of the surface acoustic wave resonator, which can ensure the acoustic reflection boundary effect.

[0065] Figure 12 A simulation quality factor improvement diagram provided by an embodiment of the present invention. Refer to Figure 12 , the high point of curve L1 is the quality factor point of the structure with added dummy fingers, and the high point of curve L2 is the quality factor point of the structure without added dummy fingers. Therefore, adding the dummy finger structure can significantly improve the quality factor of the surface acoustic wave resonator, and the acoustic wave reflection effect is good.

[0066] Figure 13 Partial structural schematic diagram of another surface acoustic wave resonator provided by an embodiment of the present invention ( Figure 13 The substrate 100 is not shown in Figure 14 is Figure 13 Cross-sectional view of the surface acoustic wave resonator in along CC'. Optionally, in an embodiment, refer to Figure 13 and Figure 14 , the shape of the dummy finger 240 is stepped, and the dummy finger 240 includes at least two step regions connected in sequence along the second direction y ( Figure 13 and Figure 14 only two step regions are shown); the height of the step region connected to the first bus bar 210 or the second bus bar 220 is equal to the first height, and the heights of the remaining step regions not connected to the first bus bar 210 or the second bus bar 220 are all less than or equal to the first height.

[0067] Optionally, on the basis of the above embodiment, refer toFigure 13 and Figure 14 Moreover, the interdigital electrode 230 has at least two heights on the surface closer to the substrate 100 side.

[0068] In the embodiment of the present invention, a better quality factor improvement effect can be achieved by setting the stepped dummy fingers.

[0069] In summary, in the present invention, by fabricating the interdigital electrode 230 in a stepped shape and setting the surface of the interdigital electrode 230 closer to the substrate 100 side to have multiple heights, or the interdigital electrode 230 to have multiple position differences in the first direction x, the acoustic impedance boundary condition of the resonance region is changed, so that the pseudo-mode of the resonator can be suppressed, and at the same time, the lateral leakage of the acoustic wave near the anchor point can be reduced and only concentrated in the middle region, and a better quality factor improvement effect can be obtained. In addition, by adding the dummy fingers 240, the acoustic reflection boundary is increased, so that the acoustic wave is concentrated in the central resonance region, and the quality factor is improved. There is a first distance between the side of the dummy finger 240 close to the interdigital electrode 230 and the side of the interdigital electrode 230 close to the dummy finger 240; the first distance is less than or equal to twice the wavelength of the acoustic wave of the surface acoustic wave resonator, which can ensure the acoustic reflection boundary effect. A better quality factor improvement effect can be achieved by setting the stepped dummy fingers.

[0070] The above specific embodiments do not constitute a limitation to the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A surface acoustic wave resonator, characterized in that: include: A substrate and an electrode layer located on one side of the substrate; The electrode layer includes a first bus bar and a second bus bar arranged in parallel along a first direction, and a plurality of interdigital electrodes alternately connected to the first bus bar or the second bus bar and arranged in parallel along a second direction; The shape of the interdigitated electrodes is step-shaped, and the interdigitated electrodes have multiple heights on the surface close to the substrate side, or the interdigitated electrodes have multiple position differences in the first direction; wherein the first direction and the second direction are perpendicular to each other; the first bus bar and the second bus bar have the same first height on the surface close to the substrate side; the height of the first step area of ​​the interdigitated electrodes connected to at least the first bus bar or the second bus bar on the surface close to the substrate side is equal to the first height; the height of other areas of the interdigitated electrodes that are not connected to the first bus bar or the second bus bar is less than or equal to the first height.

2. The surface acoustic wave resonator according to claim 1, characterized in that: The interdigital electrode further includes m step regions sequentially connected along the second direction; wherein m>2, and m is a positive integer; On the surface close to the substrate, the interdigital electrodes have n height gradients, and the interdigital electrodes have at least one depression; wherein n≥2, and n is a positive integer.

3. The surface acoustic wave resonator according to claim 2, characterized in that: The interdigital electrode further includes a second step region, a third step region, a fourth step region, a fifth step region, a sixth step region, a seventh step region, an eighth step region and a ninth step region sequentially connected along the second direction; the second step region is connected to the first step region; On the surface close to the substrate, the heights of the first step region and the ninth step region are both located at a first height gradient, the heights of the second step region and the eighth step region are both located at a second height gradient, the heights of the third step region and the seventh step region are both located at a third height gradient, the heights of the fourth step region and the sixth step region are both located at a fourth height gradient, and the height of the fifth step region is located at a fifth height gradient; The first height gradient is greater than the second height gradient, the second height gradient is greater than the third height gradient, the third height gradient is greater than the fourth height gradient, the fourth height gradient is greater than the fifth height gradient; the fifth height gradient is greater than 0; wherein the heights in the first height gradient are all equal to the first height.

4. The surface acoustic wave resonator according to claim 2, characterized in that: The interdigital electrode further includes a second step region, a third step region, a fourth step region, a fifth step region, a sixth step region, a seventh step region, an eighth step region and a ninth step region sequentially connected along the second direction; the second step region is connected to the first step region; On the surface close to the substrate, the heights of the first step region, the fifth step region and the ninth step region are all located at a sixth height gradient, the heights of the second step region, the fourth step region, the sixth step region and the eighth step region are all located at a seventh height gradient, and the heights of the third step region and the seventh step region are all located at an eighth height gradient; The sixth height gradient is greater than the seventh height gradient, and the seventh height gradient is greater than the eighth height gradient; the heights in the eighth height gradient are all greater than 0, and the heights in the sixth height gradient are all equal to the first height.

5. The surface acoustic wave resonator according to claim 2, characterized in that: The interdigital electrode further includes a second step region, a third step region, a fourth step region, a fifth step region, a sixth step region, a seventh step region, an eighth step region and a ninth step region sequentially connected along the second direction; the second step region is connected to the first step region; On the surface close to the substrate, the heights of the first step region, the third step region, the fifth step region, the seventh step region and the ninth step region are all located at an eighth height gradient, and the heights of the second step region, the fourth step region, the sixth step region and the eighth step region are all located at a ninth height gradient; The eighth height gradient is greater than the ninth height gradient, the heights in the ninth height gradient are all greater than 0 and less than or equal to two-thirds of the first height, and the heights in the eighth height gradient are all equal to the first height.

6. The surface acoustic wave resonator according to claim 1, characterized in that: On the surface close to the substrate, the interdigitated electrodes include a plurality of heights located within a plurality of height gradients and decreasing in sequence along the second direction.

7. The surface acoustic wave resonator according to claim 1, characterized in that: On a surface close to the substrate, the height of the interdigitated electrode is equal to the first height; in the first direction, the interdigitated electrode includes a plurality of step regions, and there is a position difference between each of the step regions.

8. The surface acoustic wave resonator according to any one of claims 1 to 6, characterized in that: The electrode layer also includes pseudo fingers having the same number as the interdigitated electrodes; The fake finger is arranged opposite to the interdigital electrode, and there is a first distance between a side of the fake finger close to the interdigital electrode and a side of the interdigital electrode close to the fake finger; The first distance is less than or equal to twice the wavelength of the acoustic wave of the surface acoustic wave resonator.

9. The surface acoustic wave resonator according to claim 8, characterized in that: The shape of the fake finger is a step shape, and the fake finger includes at least two step areas connected in sequence along the second direction; The height of the step area connected to the first bus bar or the second bus bar is equal to the first height, and the heights of the remaining step areas not connected to the first bus bar or the second bus bar are less than or equal to the first height.

10. The surface acoustic wave resonator according to claim 9, characterized in that: The interdigital electrodes have at least two heights on a surface close to the substrate.

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