Surface acoustic wave resonator element and electronic device including the same

Abstract

A SAW resonator element (1) comprises conductive elements (2, 3) and an active region (4) arranged between the conductive elements (2, 3) and separated from each conductive element (2, 3) by an interface region (5, 6). An electrode (9, 10) extends from each conductive element (2, 3) across one interface region (5, 6) and the active region (4) towards the other conductive element (2, 3). A dummy finger (7, 8) extends from each conductive element (2, 3) towards the active region (4). The prosthetic fingers (7, 8) and the electrodes (9, 10) are separated along the longitudinal axis (A1) by a gap (12). The artificial fingers (7, 8) and / or the electrodes (9, 10) comprise a first segment (17) having a first width (W1) and a second segment (15) having a second width (W2), the second width (W2) being greater than the first width (W1). Each second section (15) is arranged at least partially within one of the interface regions (5, 6).

Description

[0001] This application claims priority to international patent application No. PCT / EP2022 / 066189 filed on June 14, 2022, entitled “SURFACE ACOUSTIC WAVE RESONATOR ELEMENT AND ELECTRONIC APPARATUS COMPRISING SAID SURFACE ACOUSTIC WAVE RESONATOREMENT”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present invention relates to a surface acoustic wave resonator element, which comprises a conductive element, a plurality of electrodes and a plurality of pseudo fingers. The present invention also relates to an electronic device comprising the surface acoustic wave resonator element. Background Art

[0003] Surface acoustic wave (SAW) devices are devices that use the propagation of elastic waves on the surface of a material or the interface between several materials. They are often used in micromechanical resonators and filters. SAW devices use interdigitated transducers (IDTs) to convert radio-frequency (RF) signals into acoustic waves or convert acoustic waves into RF signals.

[0004] SAW devices typically include two IDTs that are spaced apart and aligned on the substrate surface so that surface acoustic waves propagate between them. The IDTs include electrode fingers that are arranged side by side with each other in the longitudinal direction (i.e., in the direction of acoustic wave propagation). These electrode fingers are typically connected alternately to a first bus bar and a second bus bar. The acoustic track refers to the substrate area through which the surface acoustic wave propagates during device operation.

[0005] One problem associated with SAW devices is the generation of transverse acoustic modes due to the lower elastic wave velocity in the IDT region than in the busbar region. Transverse modes interfere with the transmission characteristics of the device and constitute a loss mechanism.

[0006] Therefore, there is a need for a solution that can suppress unwanted acoustic waves in SAW devices to improve the performance of SAW devices. Summary of the invention

[0007] The object of the present invention is to provide an improved SAW device. The above and other objects are achieved by the features of the independent claims. Other implementations are apparent from the dependent claims, the description and the drawings.

[0008] According to a first aspect, a surface acoustic wave resonator element is provided, comprising: two conductive elements; an active region arranged between the conductive elements, the active region being separated from each conductive element by an interface region; a plurality of electrodes, wherein each electrode extends from one of the conductive elements across one of the interface regions and across the active region to another of the conductive elements; a plurality of dummy fingers, wherein the plurality of dummy fingers extend from each conductive element to the active region, each dummy finger shares a longitudinal axis with an electrode, such that an end of the dummy finger is separated from an end of the electrode by a gap, the dummy fingers and / or the electrode respectively comprising a first segment having a first width and a second segment having a second width, the second width being greater than the first width, and each second segment being at least partially arranged in one of the interface regions.

[0009] By providing wider segments, a lower velocity region is established that matches the interface region to the active region. This helps to achieve a piston-like operation mode by properly tuning the in-plane SAW dispersion in different regions. The piston operation mode is a prerequisite for the successful suppression of parasitic transverse modes of multilayer SAW resonator elements. The piston mode is achieved by matching the interface region to the active region using wider segments. The wider segments improve the waveguiding effect and thus improve the energy confinement, i.e. reduce the energy losses.

[0010] In a possible implementation manner of the first aspect, the second segment is arranged at the end of the dummy finger and / or the end of the electrode, so that the dummy finger can be matched with the electrode.

[0011] In another possible implementation of the first aspect, the first portion of the second segment is arranged on one of the dummy fingers, the second portion of the second segment is arranged on one of the electrodes, and the first portion and the second portion are separated by the gap. This can ensure that the dummy fingers do not have a negative impact on suppressing parasitic lateral modes.

[0012] In another possible implementation of the first aspect, the second segment is arranged on the electrode in a region extending in one of the interface regions. This helps to achieve another configuration for matching the pseudo finger with the electrode.

[0013] In another possible implementation of the first aspect, the surface acoustic wave resonator element includes: a first conductive element and a second conductive element;

[0014] a first interface region and a second interface region, wherein the first interface region extends between the first conductive element and the active region, and the second interface region extends between the second conductive element and the active region; a plurality of first electrodes and a plurality of second electrodes, wherein the plurality of first electrodes extend from the first conductive element across the first interface region and the active region, and the plurality of second electrodes extend from the second conductive element across the second interface region and the active region;

[0015] The first interface region includes a plurality of first pseudo fingers extending from the first conductive element toward the active region, wherein each first pseudo finger shares a longitudinal axis with one of the second electrodes, and the second interface region includes a plurality of second pseudo fingers extending from the second conductive element toward the active region, wherein each second pseudo finger shares a longitudinal axis with one of the first electrodes, which helps to realize an interdigital transducer.

[0016] In another possible implementation manner of the first aspect, the first width and the second width are measured along a transverse axis extending in a direction perpendicular to the longitudinal axis.

[0017] In another possible implementation of the first aspect, the length of the second section measured along the longitudinal axis is between 0.5×the length of the first section and 3×the length of the first section. This helps to achieve a piston operating mode, which is necessary for successfully suppressing parasitic lateral modes.

[0018] In another possible implementation of the first aspect, the length of the second section is equal to the length of the first section, which provides an optimal condition for realizing the piston working mode.

[0019] In another possible implementation of the first aspect, the dummy finger and the electrode both have a uniform thickness, and the thickness is measured in a direction perpendicular to the transverse axis and the longitudinal axis, which facilitates the manufacture of the surface acoustic wave resonator element.

[0020] In another possible implementation of the first aspect, the first segment of each dummy finger has a first thickness, the second segment of each dummy finger has a second thickness, each electrode has the second thickness in the active area, the first segment of each electrode has the first thickness, the second segment of each electrode has the second thickness in the first interface area and the second interface area, and the first thickness is less than the second thickness. Thinner segments can improve the waveguide effect, thereby improving energy confinement, that is, reducing energy loss.

[0021] In another possible implementation of the first aspect, the first electrode can be arranged alternately with the second electrode in a common plane, the first electrode is separated from the adjacent second electrode and the adjacent first pseudo finger by a longitudinal extension space, and the second electrode is separated from the adjacent first electrode and the adjacent second pseudo finger by a longitudinal extension space, each space extending from the first interface area to the second interface area, so that the common IDT structure can be used as a starting point.

[0022] In another possible implementation of the first aspect, the first electrode, the second electrode, the first dummy finger, and the second dummy finger extend in the common plane, and the first thickness and the second thickness are measured in a direction perpendicular to the common plane and the longitudinal axis. In this way, there is no need to use an electrode slope, which can reduce related loss effects.

[0023] In another possible implementation of the first aspect, the second segments arranged in the first interface region have the same length and position along the longitudinal axis, and the second segments arranged in the second interface region have the same length and position along the longitudinal axis. This helps to achieve a piston working mode, which is necessary for successfully suppressing parasitic transverse modes.

[0024] In another possible implementation of the first aspect, the one or more second segments include a substance deposited on the one or more second segments. By adding the substance, a lower speed region is established that matches the interface region with the active region, which in turn helps to achieve the piston mode.

[0025] In another possible implementation of the first aspect, the surface acoustic wave resonator element includes at least one dielectric layer extending along the transverse axis, wherein the dielectric layer partially overlaps with the active region and with one of the interface regions. This can suppress undesirable transverse modal effects. In addition, the resonance Q factor is improved.

[0026] In another possible implementation manner of the first aspect, the dielectric layer is a continuous layer covering the second segment and the gap, which can suppress the undesirable lateral modal effect.

[0027] In another possible implementation of the first aspect, the continuous dielectric layer fills any portion of the space extending between a dummy finger and one or more adjacent electrodes and any portion of the space extending between one or more adjacent electrodes, which can improve the performance of the surface acoustic wave resonator element.

[0028] According to a second aspect, an electronic device is provided, the electronic device comprising a surface acoustic wave resonator element according to any one of the above claims. This allows the electronic device comprising the surface acoustic wave resonator element to successfully suppress parasitic lateral modes.

[0029] These and other aspects will be apparent from and elucidated with reference to the embodiments described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In the following detailed description of the present invention, various aspects, embodiments and implementations are explained in more detail with reference to exemplary embodiments shown in the accompanying drawings, in which:

[0031] Figure 1 A schematic top view of a surface acoustic wave resonator element provided by an example of an embodiment of the present invention is shown;

[0032] Figure 2 Schematic and partial cross-sectional views of a device including a surface acoustic wave resonator element provided by an example of an embodiment of the present invention are shown;

[0033] Figures 3 to 6 A schematic top view of a surface acoustic wave resonator element provided by an example of an embodiment of the present invention is shown;

[0034] Figures 7 to 10 A schematic top view of a surface acoustic wave resonator element provided by another example of an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0035] The present invention relates to an electronic device, which includes at least one surface acoustic wave resonator element 1. The surface acoustic wave resonator element 1 will be described in more detail below. The electronic device can be any type of electronic device such as a tablet computer, a smart phone, etc.

[0036] The surface acoustic wave resonator element 1 may be arranged on a piezoelectric substrate structure comprising at least two layers stacked on top of each other, such as Figure 2 As shown in the shaded area in the middle. The two layers may include a piezoelectric layer and a substrate layer, the piezoelectric layer extending adjacent to the surface acoustic wave resonator element 1 and including a LiTaO3 or LiNbO3 piezoelectric material, and the substrate layer including one of Si, sapphire, SiC, quartz and YAG. For example, for LiTaO3, the Euler angle may be (0, –70 to –25,0), and for LiNbO3, the Euler angle may be (0, –75 to +40,0). The surface acoustic wave resonator element 1 may also include at least one functional layer, which is arranged between the piezoelectric layer and the substrate layer, and the functional layer includes at least one of SiO2, Si3N3, AlN and Al2O3. In other words, the functional layer may be a composite of different materials.

[0037] The surface acoustic wave resonator element 1 comprises two conductive elements 2, 3, which are also referred to as first conductive element 2 and second conductive element 3. The conductive elements 2, 3 may each be a bus bar.

[0038] like Figure 1 As shown, the active region 4 is arranged between the electrically conductive elements 2 , 3 .

[0039] The active region 4 is separated from each of the conductive elements 2, 3 by an interface region 5, 6. The first interface region 5 may extend between the first conductive element 2 and the active region 4, and the second interface region 6 may extend between the second conductive element 2 and the active region 4. In other words, the active region 4 forms a central region of the surface acoustic wave resonator element 1, the conductive elements 2, 3 form opposite edge regions of the surface acoustic wave resonator element 1, and the interface regions 5, 6 form an intermediate region connecting the central region with the edge regions.

[0040] The plurality of electrodes are arranged such that each electrode (9, 10) extends from one of the conductive elements 2, 3 across one of the interface regions 5, 6 and across the active region 4 to the other of the conductive elements 2, 3. The plurality of first electrodes 9 may extend from the first conductive element 2 across the first interface region 5 and across the active region 4. Accordingly, the plurality of second electrodes 10 may extend from the second conductive element 3 across the second interface region 6 and across the active region 4. The plurality of first electrodes 9 and the plurality of second electrodes 10 are interlaced or form interdigitated fingers, which are also commonly referred to as "fingers". "Forming interdigitated fingers" means that the active region 4 includes two groups of fingers, which are arranged such that the fingers in the first group of fingers (i.e., the first electrodes 9) are alternately arranged with the fingers in the second group of fingers (i.e., the second electrodes 10), each first finger or electrode 9 is separated from an adjacent first finger or electrode 9 by a second finger or electrode 10, and accordingly, each second finger or electrode 10 is separated from an adjacent second finger or electrode 10 by a first finger or electrode 9.

[0041] A plurality of dummy fingers 7, 8 extend from each conductive element 2, 3 to the active area 4. Each dummy finger 7, 8 shares a longitudinal axis A1 with one electrode 9, 10, such that the ends 7a, 8a of the dummy fingers 7, 8 are separated from the ends 9a, 10a of the electrodes 9, 10 by gaps 12 (preferably air gaps). For example, the first interface area 5 may include a plurality of first dummy fingers 7 extending from the first conductive element 2 to the active area 4. Correspondingly, the second interface area 6 may include a plurality of second dummy fingers 8 extending from the second conductive element 3 to the active area 4. Each first dummy finger 7 shares a longitudinal axis A1 with one of the second electrodes 10, and each second dummy finger 8 shares a longitudinal axis A1 with one of the first electrodes 9. In other words, each gap 12 separates the first dummy finger 7 from the end area 10a of the second electrode 10, or separates the second dummy finger 8 from the end area 9a of the first electrode 9. The gaps 12 form discontinuities along the longitudinal axis A1.

[0042] like Figure 1 As shown, the first electrodes 9 can be alternately arranged with the second electrodes 10 in a common plane P1, the first electrodes 9 are separated from the adjacent second electrodes 10 and the adjacent first dummy fingers 7 by longitudinally extending spaces 13, and the second electrodes 10 are separated from the adjacent first electrodes 9 and the adjacent second dummy fingers 8 by longitudinally extending spaces 13, and each space 13 extends from the first interface region 5 to the second interface region 6. In other words, each first electrode 9 is separated from the adjacent second electrode 10 by a space 13, and correspondingly, each second electrode 10 is separated from the adjacent first electrode 9 by a space 13.

[0043] The length of the pseudo fingers 7, 8 along the longitudinal axis A1 may be between 1×electrode pitch and 6×electrode pitch, where the electrode pitch is the distance between the central axes of adjacent electrodes, such as Figure 1 As indicated by the double-headed arrow in .

[0044] The dummy finger 7, 8 and / or the electrode 9, 10 comprises a first section 17 having a first width W1 and a second section 15 having a second width W2. The second width W2>the first width W1, i.e. the second width W2 is greater than the first width W1. In other words, the second section 15 represents a local area that is wider than the rest of the dummy finger 7, 8 or the electrode 9, 10. The first width W1 and the second width W2 can be measured by a transverse axis A2 extending in a direction perpendicular to the longitudinal axis A1.

[0045] The length L2 of the second segment 15 measured along the longitudinal axis A1 may be between 0.5×the length L1 of the first segment 17 and 3×the length L1 of the first segment 17. In other words, the length of the second segment 15 is between half the length of the first segment 17 and three times the length of the first segment 17. The length L2 of the second segment 15 may be equal to the length L1 of the first segment 17.

[0046] All second segments 15 arranged in the first interface area 5 may have the same length L2 and position along the longitudinal axis A1. Correspondingly, all second segments 15 arranged in the second interface area 6 may have the same length L2 and position along the longitudinal axis A1. "Position" means that the second segments 15 start and end at the same coordinates along the longitudinal axis A1.

[0047] Each second section 15 is arranged at least partially in one of the interface regions 5 , 6 .

[0048] The second section 15 can be arranged at the end 7a, 8a of the false finger 7, 8, such as Figure 3 and Figure 7 The second section 15 can also be arranged at the ends 9a, 10a of the electrodes 9, 10, as shown. Figure 4 and Figure 8 as shown in the top portion of .

[0049] like Figure 6 and Fig.10 As shown in the top part of , the first part 15a of the second segment 15 can be arranged on one of the pseudo fingers 7, 8, and the second part 15b of the second segment 15 can be arranged on one of the electrodes 9, 10, and the first part 15a and the second part 15b are separated by the gap 12.

[0050] like Figure 4 , Figure 5 , Figure 8 and Fig. 9 As shown in the top part of , the second section 15 can be arranged on the electrodes 9 , 10 in a region extending within one of the interface regions 5 , 6 .

[0051] like Figure 4 , Figure 5 , Figure 8 and Fig. 9 As shown in the bottom part of , the second section 15 can be arranged on the electrodes 9 , 10 in a region extending in one of the interface regions 5 , 6 .

[0052] like Figure 3 , Figure 6 , Figure 7 and Fig.10 As shown in the bottom part of , further second segments 15 can be arranged on electrodes 9 , 10 located in the active area 4 .

[0053] like Figures 3 to 6 As shown, the pseudo fingers 7, 8 and the electrodes 9, 10 may have a uniform thickness measured in a direction D1 perpendicular to the transverse axis A2 and the longitudinal axis A1.

[0054] like Figure 2 and Figures 7 to 10 As shown by the shaded area, the first section 17 of each dummy finger 7, 8 may have a first thickness T1, and the second section 15 of each dummy finger 7, 8 may have a second thickness T2. Each electrode 9, 10 has a corresponding second thickness T2 in the active area, that is, each portion of the electrode 9, 10 extending in the active area 4 has a uniform topology with a thickness equal to the second thickness T2.

[0055] In addition, if Figures 7 to 10 As indicated by the shaded areas, the first section 17 of each electrode 9, 10 may have a first thickness T1 and the second section 15 of each electrode 9, 10 may have a second thickness T2 in the first interface region 5 and the second interface region 6. Each electrode 9, 10 has a second thickness T2 in the active region.

[0056] The first thickness T1<the second thickness T2, that is, the first thickness T1 is smaller than the second thickness T2.

[0057] The second segment 15 may include a substance (not shown) deposited on the second segment 15 .

[0058] The surface acoustic wave resonator element 1 may further include at least one dielectric layer 16 extending along the above-mentioned transverse axis A2, wherein the dielectric layer 16 partially overlaps the active region 4 and one of the interface regions 5 and 6, i.e., overlaps the first interface region 5 and the active region 4 or overlaps the second interface region 6 and the active region 4. In other words, the dielectric layer 16 covers the boundary region between the first interface region 5 and the active region 4 or the boundary region between the second interface region 6 and the active region 4.

[0059] The dielectric layer 16 may be a continuous layer covering the second section 15 and the gap 12. By "continuous" is meant that the dielectric layer 16 extends without interruption and forms one solid substance.

[0060] The continuous dielectric layer 16 may fill any portion of the space 13 extending between one dummy finger 7, 8 and one or more adjacent electrodes 9, 10, and any portion of the space 13 extending between adjacent electrodes 9, 10. In other words, the continuous dielectric layer 16 may extend coplanar with the electrodes 9, 10 and the dummy fingers 7, 8 in a common plane P1 to some extent, and coplanar with the electrodes 9, 10 and the dummy fingers 7, 8 on top of each other to some extent.

[0061] The length of the dielectric layer 16 measured along the longitudinal axis A1 may be at least 2×the length L2 of the second segment 15. This length may be equal to 2×the length L2 plus the length of the gap 12 along the longitudinal axis A1. In other words, the length of the dielectric layer 16 is at least twice the length L2 of the second segment 15.

[0062] The surface acoustic wave resonator element 1 can be manufactured by an electrode manufacturing method, which includes: forming a photoresist pattern on a layered substrate, depositing an Al / Cr / Al composite material or the like to form an etching stop thin conductive layer, stripping / removing the photoresist pattern, forming another photoresist pattern, etching the top Al layer, and stripping / removing another photoresist pattern. For example, the Cr layer can be Cu or Ag.

[0063] Another method of manufacturing the surface acoustic wave resonator element 1 includes: depositing an Al layer on a layered substrate, forming a photoresist pattern, depositing another Al layer, stripping / removing the photoresist pattern, forming another photoresist pattern, etching the top Al layer, and stripping / removing another photoresist pattern.

[0064] Various aspects and implementations have been described herein in conjunction with various embodiments. However, other variations of the disclosed embodiments can be understood and implemented by those skilled in the art in practicing the claimed subject matter by studying the drawings, the present invention, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and "a" or "an" does not exclude a plurality. The enumeration of certain measures in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0065] The reference numerals used in the claims should not be construed as limiting the scope. Unless otherwise indicated, the drawings (e.g., cross-hatching, arrangement of parts, proportions, degrees, etc.) should be read in conjunction with the specification and should be considered part of the entire written description of the invention. As used herein, the terms "horizontal," "vertical," "left," "right," "upper," and "lower," and their adjectival and adverbial derivatives (e.g., "horizontally," "to the right," "upward," etc.) refer only to the direction of the structure shown when a particular drawing is facing the reader. Similarly, the terms "inward" and "outward" generally refer to the direction of a surface relative to its axis of elongation or axis of rotation, as the case may be.

Claims

1. A surface acoustic wave resonator element (1), It is characterized in that include: two conductive elements (2, 3); an active region (4) arranged between the conductive elements (2, 3); The active region (4) is separated from each conductive element (2, 3) by an interface region (5, 6); a plurality of electrodes (9, 10), wherein each electrode (9, 10) extends from one of the conductive elements (2, 3) across one of the interface regions (5, 6) and across the active region (4) to the other of the conductive elements (2, 3); a plurality of dummy fingers (7, 8), wherein the plurality of dummy fingers (7, 8) extend from each conductive element (2, 3) toward the active region (4), each dummy finger (7, 8) sharing a longitudinal axis (A1) with an electrode (9, 10), such that an end (7a, 8a) of the dummy finger (7, 8) is separated from an end (9a, 10a) of the electrode (9, 10) by a gap (12); The dummy finger (7, 8) and / or the electrode (9, 10) respectively comprises a first segment (17) having a first width (W1) and a second segment (15) having a second width (W2), wherein the second width (W2) is greater than the first width (W1), Each second section (15) is arranged at least partially within one of the interface regions (5, 6).

2. The surface acoustic wave resonator element (1) according to claim 1, It is characterized in that The second section (15) is arranged at the end (7a, 8a) of the pseudo finger (7, 8) and / or at the end (9a, 10a) of the electrode (9, 10).

3. The surface acoustic wave resonator element (1) according to claim 2, It is characterized in that The first portion (15a) of the second segment (15) is arranged on one of the pseudo fingers (7, 8), and the second portion (15b) of the second segment (15) is arranged on one of the electrodes (9, 10), and the first portion (15a) and the second portion (15b) are separated by the gap (12).

4. A surface acoustic wave resonator element (1) according to any one of the preceding claims, It is characterized in that The second section (15) is arranged on the electrode (9, 10) in a region extending within one of the interface regions 5, 6.

5. The surface acoustic wave resonator element (1) according to any one of the preceding claims, It is characterized in that include: A first conductive element (2) and a second conductive element (3); a first interface region (5) and a second interface region (6), wherein the first interface region (5) extends between the first conductive element (2) and the active region (4), and the second interface region (6) extends between the second conductive element (2) and the active region (4); a plurality of first electrodes (9) and a plurality of second electrodes (10), wherein the plurality of first electrodes (9) extend from the first conductive element (2) across the first interface region (5) and the active region (4), and the plurality of second electrodes (10) extend from the second conductive element (3) across the second interface region (6) and the active region (4); The first interface region (5) comprises a plurality of first dummy fingers (7) extending from the first conductive element (2) toward the active region (4), wherein each first dummy finger (7) shares a longitudinal axis (A1) with one of the second electrodes (10), The second interface region (6) comprises a plurality of second dummy fingers (8) extending from the second conductive element (3) towards the active region (4), wherein each second dummy finger (8) shares a longitudinal axis (A1) with one of the first electrodes (9).

6. A surface acoustic wave resonator element (1) according to any one of the preceding claims, It is characterized in that The first width (W1) and the second width (W2) are measured from a transverse axis (A2) extending in a direction perpendicular to the longitudinal axis (A1).

7. A surface acoustic wave resonator element (1) according to any one of the preceding claims, It is characterized in that The length (L2) of the second section (15) measured along the longitudinal axis (A1) is between 0.5×the length (L1) of the first section (17) and 3×the length (L1) of the first section (17).

8. The surface acoustic wave resonator element (1) according to claim 7, It is characterized in that The length (L2) of the second section (15) is equal to the length (L1) of the first section (17).

9. A surface acoustic wave resonator element (1) according to any one of the preceding claims, It is characterized in that The pseudo fingers (7, 8) and the electrodes (9, 10) have a uniform thickness, which is measured in a direction perpendicular to the transverse axis (A2) and the longitudinal axis (A1).

10. The surface acoustic wave resonator element (1) according to any one of claims 1 to 8, It is characterized in that The first section (17) of each dummy finger (7, 8) has a first thickness (T1), the second section (15) of each dummy finger (7, 8) has a second thickness (T2), each electrode (9, 10) has the second thickness (T2) in the active area, the first section (17) of each electrode (9, 10) has the first thickness (T1), the second section (15) of each electrode (9, 10) has the second thickness (T2) in the first interface area (5) and the second interface area (6), and the first thickness (T1) is less than the second thickness (T2).

11. The surface acoustic wave resonator element (1) according to any one of the preceding claims, It is characterized in that It also includes at least one dielectric layer (16) extending along the transverse axis (A2), wherein the dielectric layer (16) partially overlaps the active area (4) and one of the interface areas (5, 6).

12. The surface acoustic wave resonator element (1) according to claim 11, It is characterized in that The dielectric layer (16) is a continuous layer covering the second segment (15) and the gap (12).

13. The surface acoustic wave resonator element (1) according to claim 12, It is characterized in that The continuous dielectric layer (16) fills any portion of the space (13) extending between a dummy finger (7, 8) and one or more adjacent electrodes (9, 10) and Any part of the space (13) extending between one or more adjacent electrodes (9, 10).

14. An electronic device, It is characterized in that The invention comprises a surface acoustic wave resonator element (1) according to any one of the preceding claims.

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