CN118138004A

CN118138004A - Surface acoustic wave resonator, preparation method thereof and filter

Info

Publication number: CN118138004A
Application number: CN202311366431.5A
Authority: CN
Inventors: 高安明; 路晓明; 姜伟
Original assignee: Zhejiang Xingyao Semiconductor Co ltd
Current assignee: Zhejiang Xingyao Semiconductor Co ltd
Priority date: 2023-10-20
Filing date: 2023-10-20
Publication date: 2024-06-04

Abstract

The invention provides a surface acoustic wave resonator, a preparation method thereof and a filter, wherein at least two piston structures are formed in the tail end area of an electrode finger, and a larger sound velocity difference is realized by changing the sound velocity of the tail end area of the electrode finger, so that transverse modes reflect in different directions to avoid energy dissipation caused by resonance, compared with the scheme of a single piston structure in the prior art, the at least two piston structures are not simple superposition of the inhibition effect of the single piston structure, more adjustable parameters are introduced, the application range of the surface acoustic wave resonator can be enlarged, the process difficulty of the single piston structure is overcome, and the area of the surface acoustic wave resonator can be reduced through deformation fit.

Description

Surface acoustic wave resonator, preparation method thereof and filter

Technical Field

The invention relates to the technical field of semiconductor structures, in particular to a surface acoustic wave resonator, a preparation method thereof and a filter.

Background

The SAW (Surface Acoustic Wave ) resonator is a short term of surface acoustic wave resonator, is a special filter device made by utilizing the piezoelectric effect and the physical characteristics of surface acoustic wave propagation, and is widely applied to various fields, such as the radio frequency field. Wherein a surface acoustic wave is an elastic wave in which energy is concentrated near a surface.

In the current surface acoustic wave product design, a transverse resonant mode of the surface acoustic wave resonator, namely clutter in and near the passband, occurs due to the sound waves transversely propagated by the surface acoustic wave resonator, and the clutter can increase the loss of the surface acoustic wave resonator, so that the Q value is greatly fluctuated, and the performance of the surface acoustic wave resonator is reduced.

How to suppress the interference of the hybrid mode and increase the Q value, thereby improving the performance of the surface acoustic wave resonator is a serious problem in the design of the present resonator.

Disclosure of Invention

In view of the above, the present invention provides a surface acoustic wave resonator, a method for manufacturing the same, and a filter, wherein the method comprises the following steps:

a surface acoustic wave resonator, the surface acoustic wave resonator comprising:

a piezoelectric substrate;

An interdigital electrode positioned on one side of the piezoelectric substrate; the interdigital electrode includes a bus bar including a first bus bar and a second bus bar disposed opposite to each other in a first direction, and an electrode finger on the first bus bar and the second bus bar; the bus bars extend along a second direction, the length extension directions of the electrode finger bars are parallel to the first direction, the first direction and the second direction are parallel to the plane of the piezoelectric substrate, and the first direction and the second direction are vertical;

The electrode finger strip comprises a first piston structure, a second piston structure and a third piston structure which are sequentially arranged in the first direction, wherein N is more than or equal to 2, N is a positive integer, and the first piston structure is positioned at one end, away from the bus bar, where the electrode finger strip is correspondingly connected;

the electrode finger strip further comprises a first matching structure to an N-th matching structure which are sequentially arranged in the first direction, an i-th piston structure and an i-th matching structure are oppositely arranged in the second direction, i is more than 1 and less than or equal to N, i is a positive integer, and the orthographic projection pattern of the i-th piston structure on the piezoelectric substrate is the same as the orthographic projection pattern of the i-th matching structure on the piezoelectric substrate;

Wherein the maximum width of the piston structure in the second direction is greater than the width of the electrode finger in the second direction.

Preferably, in the surface acoustic wave resonator, the interdigital electrode further includes:

And a plurality of dummy electrode fingers on the bus bar, wherein a length extending direction of the dummy electrode fingers is parallel to the first direction.

Preferably, in the surface acoustic wave resonator, the dummy electrode finger includes first to M-th additional piston structures sequentially arranged in the first direction, M is greater than or equal to 1, and M is a positive integer, and the first additional piston structure is located at one end of the dummy electrode finger away from the bus bar to which the dummy electrode finger is correspondingly connected;

The electrode finger strip further comprises first to M additional matching structures which are sequentially arranged in the first direction, the j additional piston structures and the j additional matching structures are oppositely arranged in the second direction, j is more than or equal to 1 and less than or equal to M, j is a positive integer, and the orthographic projection pattern of the j additional piston structures on the piezoelectric substrate is the same as the orthographic projection pattern of the j additional matching structures on the piezoelectric substrate.

Preferably, in the above surface acoustic wave resonator, the surface acoustic wave resonator further includes:

and the reflecting grating is positioned at least one end of the interdigital electrode along the second direction.

And a reflective grating piston structure positioned on the reflective grating.

Preferably, in the surface acoustic wave resonator, when N > 2, a spacing between two adjacent piston structures in the first direction is different.

Preferably, in the surface acoustic wave resonator, an orthographic projection pattern of the piston structure on the piezoelectric substrate is polygonal, circular or elliptical.

Preferably, in the surface acoustic wave resonator, when N orthographic projection patterns of the piston structures on the piezoelectric substrate are the same, orthographic projection areas of at least two piston structures on the piezoelectric substrate are different.

Preferably, in the surface acoustic wave resonator, orthographic projection patterns of at least two piston structures on the piezoelectric substrate are different.

Preferably, in the surface acoustic wave resonator, the first bus bar includes a first bus bar and a first second bus bar that are disposed opposite to each other in the first direction, and the first bus bar and the first second bus bar have the same length extension direction and are parallel to the second direction;

The second bus bar comprises a second first bus bar and a second bus bar which are oppositely arranged in the first direction, and the length extension directions of the second first bus bar and the second bus bar are the same and are parallel to the second direction;

wherein the first and second ethylene bus bars are located between the first and second first bus bars.

Preferably, in the surface acoustic wave resonator, the orthographic projection patterns of the first and second bus bars on the piezoelectric substrate are a straight line pattern, a broken line pattern or a curved line pattern.

Preferably, in the surface acoustic wave resonator, the orthographic projection patterns of the first and second b bus bars on the piezoelectric substrate are different.

Preferably, in the surface acoustic wave resonator, when n=2, a length of the first piston structure in the first direction is a, a length of the second piston structure in the first direction is B, and a distance between the first piston structure and the second piston structure in the first direction is C;

Wherein A: c: b=0.4-1: 0.5:0.4-1, and the duty cycle of the piston structure is 0.69-0.72.

The application also provides a preparation method of the surface acoustic wave resonator, which comprises the following steps:

Providing a piezoelectric substrate;

Forming interdigital electrodes on one side of the piezoelectric substrate; wherein the interdigital electrode comprises a bus bar comprising a first bus bar and a second bus bar which are oppositely arranged in a first direction, and an electrode finger bar positioned on the first bus bar and the second bus bar; the length extension directions of the first bus bar and the second bus bar are the same, the first bus bar and the second bus bar extend along a second direction, the first direction and the second direction are parallel to the plane of the piezoelectric substrate, and the first direction and the second direction are vertical; the electrode finger strip comprises a first piston structure, a second piston structure and a third piston structure which are sequentially arranged in the first direction, wherein N is more than or equal to 2, N is a positive integer, and the first piston structure is positioned at one end, away from the bus bar, where the electrode finger strip is correspondingly connected; the electrode finger strip further comprises a first matching structure to an N-th matching structure which are sequentially arranged in the first direction, an i-th piston structure and the i-th matching structure are oppositely arranged in the second direction, i is more than or equal to 1 and less than or equal to N, i is a positive integer, and the orthographic projection pattern of the i-th piston structure on the piezoelectric substrate is the same as the orthographic projection pattern of the i-th matching structure on the piezoelectric substrate; wherein the maximum width of the piston structure in the second direction is greater than the width of the electrode finger in the second direction.

The application also provides a filter comprising the surface acoustic wave resonator according to any one of the above.

Compared with the prior art, the invention has the following beneficial effects:

According to the surface acoustic wave resonator, the preparation method and the filter thereof, the at least two piston structures are formed in the tail end area of the electrode finger strip, and the larger sound velocity difference is realized by changing the sound velocity of the tail end area of the electrode finger strip, so that the transverse mode is reflected in different directions to avoid energy dissipation caused by resonance, compared with the scheme of a single piston structure in the prior art, the at least two piston structures are not simple superposition of the inhibition effect of the single piston structure, more adjustable parameters are introduced, the application range of the surface acoustic wave resonator can be enlarged, the process difficulty of the single piston structure is overcome, and the area of the surface acoustic wave resonator can be reduced through deformation fit.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only embodiments of the present invention, and that other drawings can be obtained according to the provided drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic top view of a surface acoustic wave resonator according to an embodiment of the present invention;

fig. 2 is a schematic top view of another surface acoustic wave resonator according to an embodiment of the present invention;

Fig. 3 is a schematic top view of a surface acoustic wave resonator according to an embodiment of the present invention;

Fig. 4 is a schematic top view of a surface acoustic wave resonator according to an embodiment of the present invention;

fig. 5 is a schematic top view of a surface acoustic wave resonator according to an embodiment of the present invention;

Fig. 6 is a schematic top view of a surface acoustic wave resonator according to an embodiment of the present invention;

fig. 7 is a schematic top view of a surface acoustic wave resonator according to an embodiment of the present invention;

fig. 8 is a schematic top view of a surface acoustic wave resonator according to an embodiment of the present invention;

fig. 9 is a schematic top view of a surface acoustic wave resonator according to another embodiment of the present invention;

fig. 10 is a schematic top view of a surface acoustic wave resonator according to another embodiment of the present invention;

fig. 11 is a schematic top view of a surface acoustic wave resonator according to an embodiment of the present invention;

fig. 12 is a schematic top view of a surface acoustic wave resonator according to an embodiment of the present invention;

fig. 13 is a schematic top view of a surface acoustic wave resonator according to another embodiment of the present invention;

fig. 14 is a schematic top view of a surface acoustic wave resonator according to another embodiment of the present invention;

fig. 15 is a schematic top view of a surface acoustic wave resonator according to another embodiment of the present invention;

fig. 16 is a schematic top view of a surface acoustic wave resonator according to an embodiment of the present invention;

fig. 17 is a schematic top view of a surface acoustic wave resonator according to another embodiment of the present invention;

fig. 18 is a schematic top view of a surface acoustic wave resonator according to an embodiment of the present invention;

FIG. 19 is a schematic diagram of a prior art surface wave resonator with a single piston structure;

FIG. 20 is a schematic diagram of a performance curve of a surface wave resonator of another single piston structure according to the prior art;

FIG. 21 is a schematic diagram of a performance curve of a SAW resonator with a dual-piston structure according to an embodiment of the present invention;

FIG. 22 is a schematic diagram of a performance curve of a SAW resonator with another dual-piston structure according to an embodiment of the present invention;

FIG. 23 is a schematic diagram of a performance curve of a SAW resonator with a dual piston structure according to an embodiment of the present invention;

FIG. 24 is a schematic diagram of a performance curve of a SAW resonator with a dual piston structure in accordance with an embodiment of the present invention;

FIG. 25 is a schematic diagram showing a comparison of admittance versus frequency curves of FIGS. 22-24;

FIG. 26 is a schematic diagram showing a comparison of the conductance-frequency curves of FIGS. 22-24;

FIG. 27 is a schematic diagram of a performance curve of a surface wave resonator of yet another prior art single piston structure;

FIG. 28 is a schematic diagram of a surface wave resonator of yet another prior art single piston structure;

fig. 29 is a schematic diagram of a performance curve of a surface acoustic wave resonator with a dual-piston structure according to an embodiment of the present invention;

FIG. 30 is a schematic diagram of a performance curve of a SAW resonator with a dual piston structure according to an embodiment of the present invention;

Fig. 31 is a schematic flow chart of a method for manufacturing a surface acoustic wave resonator according to an embodiment of the present invention.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

The surface acoustic wave resonator and the filter are acoustic devices widely applied to the radio frequency field, integrate low insertion loss and good inhibition performance, have smaller volume, are used for filtering interference of different-frequency signals, attenuate partial frequency components, only allow specified frequency components to pass through, and are the technical foundation for applying a wireless frequency spectrum as a non-renewable scarce resource. The specific principle can be simply understood as that based on the piezoelectric characteristics of piezoelectric materials, the input and output transducer devices such as interdigital transducers are utilized to convert electric signals into mechanical energy, and the mechanical energy is converted into electric signals after being processed, so that the effects of amplifying required signals, filtering out impurity signals and improving signal quality are achieved, and the piezoelectric transducer is widely applied to various wireless communication equipment.

Currently, filters are largely classified into SAW filters and BAW (Bulk Acoustic Wave ) filters, in which a surface acoustic wave is an elastic wave that is generated and propagates on the surface of a piezoelectric substrate having piezoelectric characteristics, and whose amplitude rapidly decreases with increasing depth into the piezoelectric substrate. For the SAW filter, the manufacturing cost is much lower than that of the BAW filter, and the SAW filter is applied to a low frequency band, has low insertion loss, good inhibition and temperature sensitivity.

Meanwhile, it should be noted that, the SAW filter has a corresponding limitation in that it is susceptible to temperature change, when the temperature increases, the rigidity of the substrate material tends to decrease, and the sound velocity also decreases, which is also known as a defect that the SAW filter has temperature drift, i.e. the frequency drift along with the working temperature, so that, based on the conventional SAW filter, a TC-SAW filter, i.e. a temperature compensation type SAW filter, is correspondingly generated, and the compensation of the temperature drift characteristic is realized mainly by using the temperature elastic characteristic of the SiO ₂ layer opposite to the piezoelectric layer. Further, SAW filters and products such as TF thin film SAW filters are also designed.

In which the filter is designed by using resonators as basic units, a corresponding topology can be constructed and the signal of the specified frequency component can be amplified.

For a TC-SAW resonator or a common SAW resonator or a TF-SAW resonator, a transverse resonant mode of the SAW resonator, namely clutter in and near a passband, occurs in the SAW resonator due to the sound waves transversely propagated by the SAW resonator, and the clutter can increase the loss of the SAW resonator, so that the Q value is greatly fluctuated, and the performance of the SAW resonator is reduced.

In the prior art, a single Piston structure (Piston) is added at the tail end of the electrode finger, namely a sound velocity change structure is adopted, namely, a larger sound velocity difference is realized by changing the sound velocity in the region, so that the transverse mode is reflected in different directions to avoid energy dissipation caused by resonance. However, the adjustable range of a single piston structure is greatly limited by the process, such as the duty ratio, so that the difference of the inhibition effect is larger in different application scenes, and the application range is greatly limited; meanwhile, the single piston structure has limited inhibiting effect on the high-order transverse mode.

The embodiment of the invention provides the surface acoustic wave resonator, the preparation method thereof and the filter, solves the technical problems in the prior art, and at least two piston structures arranged in the tail end area of the electrode finger strip bring the effects of breaking through the single piston structure parameter adjustment limit and the process limit, has a larger performance adjustment range and higher adjustment sensitivity, and can improve the high-order transverse mode suppression effect and reduce the area of the surface acoustic wave resonator by being matched with other schemes.

It should be noted that the SAW resonator provided by the embodiment of the present invention includes, but is not limited to, a common SAW resonator, a TC-SAW resonator, or a TF-SAW resonator, that is, the technical solution provided by the embodiment of the present invention may be applied to a common SAW resonator, a TC-SAW resonator, or a TF-SAW resonator.

In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.

Referring to fig. 1, fig. 1 is a schematic top view of a surface acoustic wave resonator according to an embodiment of the present invention, referring to fig. 2, fig. 2 is a schematic top view of another surface acoustic wave resonator according to an embodiment of the present invention, where the surface acoustic wave resonator according to the embodiment of the present invention includes:

A piezoelectric substrate 11, the piezoelectric substrate 11 having piezoelectric characteristics.

An interdigital electrode 12 located on one side of the piezoelectric substrate 11; wherein the interdigital electrode 12 includes a bus bar including a first bus bar 121 and a second bus bar 122 disposed opposite in a first direction X, and an electrode finger 123 on the first bus bar 121 and the second bus bar 122; the first bus bar 121 and the second bus bar 122 have the same length extending direction and extend along the second direction Y, and the first direction X and the second direction Y are parallel to the plane of the piezoelectric substrate 11 and are described as being perpendicular to the first direction X.

The length extending direction of the electrode finger strips 123 is parallel to the first direction X, the electrode finger strips 123 on the first bus bar 121 are arranged at intervals in the second direction Y, the electrode finger strips 123 on the second bus bar 122 are arranged at intervals in the second direction Y, the electrode finger strips 123 on the first bus bar 121 and the electrode finger strips 123 on the second bus bar 122 are arranged in a crossed manner in sequence in the second direction Y, and spaces are reserved between the electrode finger strips 123 on the first bus bar 121 and the second bus bar 122, spaces are reserved between the electrode finger strips 123 on the second bus bar 122 and the first bus bar 121, and at this time, the bus bars and the electrode finger strips 123 are distributed in a similar finger crossing manner to form a so-called interdigital electrode 12. When the first bus bar 121 and the electrode finger 123 thereon are used as the transmitting end, the second bus bar 122 and the electrode finger 123 thereon are used as the receiving end, whereas when the first bus bar 121 and the electrode finger 123 thereon are used as the receiving end, the second bus bar 122 and the electrode finger 123 thereon are used as the transmitting end. The transmitting end part is used for converting the electric signal into sound waves, the sound waves mainly propagate on the surface of the piezoelectric substrate, and the receiving end part is used for converting the received sound waves into electric signal output, so that filtering is realized.

The electrode finger 123 includes first to nth piston structures 13 to 13 sequentially arranged in the first direction X, N is greater than or equal to 2, N is a positive integer, the first piston structure 13 is located at one end of the electrode finger 123 away from the bus bar to which the electrode finger 123 is correspondingly connected, it may also be understood that the first piston structure 13 is located at the end of the electrode finger 123, as shown in fig. 1, and the electrode finger 123 includes first and second piston structures 13 and 14 sequentially arranged in the first direction X, as shown in fig. 2, and the electrode finger 123 includes first, second and third piston structures 13, 14 and 17 sequentially arranged in the first direction X.

The electrode finger 123 further includes first to nth matching structures 15 to 15 sequentially arranged in the first direction X, the ith piston structure is disposed opposite to the ith matching structure in the second direction Y, 1 < i is equal to N, and i is a positive integer, an orthographic projection pattern of the ith piston structure on the piezoelectric substrate 11 is identical to an orthographic projection pattern of the ith matching structure on the piezoelectric substrate 11, as illustrated in fig. 1, the electrode finger 123 further includes first and second matching structures 15 and 16 sequentially arranged in the first direction X, as illustrated in fig. 2, and the electrode finger 123 further includes first, second and third matching structures 15, 16 and 18 sequentially arranged in the first direction X. The first piston structure 13 and the first matching structure 15 are arranged opposite each other in the second direction Y, the second piston structure 14 and the second matching structure 16 are arranged opposite each other in the second direction Y, and the third piston structure 17 and the third matching structure 18 are arranged opposite each other in the second direction Y.

In fig. 1, n=2 is taken as an example, in fig. 2, n=3 is taken as an example, and the determination of the N value may be determined according to practical situations, and in the embodiment of the present invention, the determination is not limited, and N is only required to be ensured to be greater than or equal to 2, and N is a positive integer.

Wherein the maximum width of the piston structure in the second direction Y is greater than the width of the electrode finger 123 in the second direction Y.

Specifically, in the embodiment of the present invention, at least two piston structures are formed in the end area of the electrode finger 123, and a larger sound velocity difference is achieved by changing the sound velocity of the end area of the electrode finger 123, so that the transverse mode reflects in different directions to avoid energy dissipation caused by resonance, and compared with the scheme of a single piston structure set in the prior art, the at least two piston structures set in the embodiment of the present invention are not simple superposition of the suppression effect of the single piston structure, but introduce more adjustable parameters, so that the application range of the surface acoustic wave resonator can be enlarged, the process difficulty of the single piston structure is overcome, and the area of the surface acoustic wave resonator can be reduced through deformation fit.

That is, the at least two piston structures provided in the embodiment of the invention bring the effect of breaking through the single piston structure parameter adjustment limit and the process limit, have a larger performance adjustment range and higher adjustment sensitivity, and can improve the higher-order transverse mode suppression effect and reduce the area of the surface acoustic wave resonator by being matched with other schemes.

Optionally, in another embodiment of the present invention, referring to fig. 3, fig. 3 is a schematic top view structure of another surface acoustic wave resonator provided in the embodiment of the present invention, and the interdigital electrode 12 in the surface acoustic wave resonator provided in the embodiment of the present invention may further include:

The plurality of dummy electrode fingers 124, wherein the length extension direction of the dummy electrode fingers 124 is parallel to the first direction X, the plurality of dummy electrode fingers 124 are disposed on the first bus bar 121, the plurality of dummy electrode fingers 124 are disposed on the second bus bar 122, the plurality of dummy electrode fingers 124 and the plurality of electrode fingers 123 on the first bus bar 121 are sequentially and alternately arranged in the second direction Y, the plurality of dummy electrode fingers 124 and the plurality of electrode fingers 123 on the second bus bar 123 are sequentially and alternately arranged in the second direction Y, the electrode fingers 123 on the first bus bar 121 are disposed opposite to the dummy electrode fingers 124 on the second bus bar 122 with a space therebetween, the dummy electrode fingers 124 on the first bus bar 121 are disposed opposite to the electrode fingers 123 on the second bus bar 122 with a space therebetween.

That is, the interdigital electrode 12 may be adopted as the interdigital electrode 12 without the dummy electrode finger 124 shown in fig. 1 and 2, or the interdigital electrode 12 with the dummy electrode finger 124 shown in fig. 3.

When the interdigital electrode 12 is provided with the dummy electrode finger 124, the dummy electrode finger 124 is also provided to suppress noise and improve the quality factor of the surface acoustic wave resonator.

Optionally, in another embodiment of the present invention, referring to fig. 4, fig. 4 is a schematic top view structure of another saw resonator provided in the embodiment of the present invention, where the interdigital electrode 12 includes a dummy electrode finger 124, the dummy electrode finger 124 includes first to mth additional piston structures 19 to M additional piston structures sequentially arranged in the first direction X, M is greater than or equal to 1, and M is a positive integer, the first additional piston structure 19 is located at an end of the dummy electrode finger 124 away from a bus bar to which the dummy electrode finger 124 is correspondingly connected, which may also be understood that the first additional piston structure 19 is located at an end of the dummy electrode finger 124, as shown in fig. 4 by way of example, the dummy electrode finger 124 includes the first additional piston structure 19.

The electrode finger 123 further includes first to M-th additional matching structures 20 to M-th additional matching structures sequentially arranged in the first direction X, and j-th additional piston structures are disposed opposite to the j-th additional matching structures in the second direction Y, where j is a positive integer, and an orthographic projection pattern of the j-th additional piston structures on the piezoelectric substrate 11 is the same as an orthographic projection pattern of the j-th additional matching structures on the piezoelectric substrate 11, and as illustrated in fig. 4, the electrode finger 123 further includes first additional matching structures 20, and the first additional matching structures 20 and the first additional piston structures 19 are disposed opposite to each other in the second direction Y.

Specifically, in the embodiment of the present invention, at least one additional piston structure is formed in the end region of the dummy electrode finger 124, thereby forming an additional sound velocity change region, thereby further enhancing the suppression effect.

Optionally, in another embodiment of the present invention, referring to fig. 5, fig. 5 is a schematic top view structure of another surface acoustic wave resonator provided in an embodiment of the present invention, where the surface acoustic wave resonator provided in the embodiment of the present invention further includes:

The reflective grating 21 located at least one end of the interdigital electrode 12 along the second direction Y is described by taking the reflective grating 21 provided at both ends of the interdigital electrode 12 along the second direction Y as an example in the embodiment of the present invention.

Specifically, in the embodiment of the present invention, a reflective grating 21 may be further disposed at least one end of the interdigital electrode 12 along the second direction Y, so as to reflect the sound wave back to the resonance area, so that the sound wave continues to form resonance in the resonance area, thereby forming better resonance effect and mode, and improving the transmission performance of the surface acoustic wave resonator.

Optionally, in another embodiment of the present invention, referring to fig. 6, fig. 6 is a schematic top view structure of another surface acoustic wave resonator provided in an embodiment of the present invention, where the surface acoustic wave resonator provided in the embodiment of the present invention further includes:

A reflective grating piston structure 22 located on said reflective grating 21.

Specifically, the suppression effect is further enhanced in the embodiment of the present invention by adding some reflective grating piston structures 22 at corresponding positions of the reflective grating 21.

It is obvious that in some alternative embodiments, the technical solution of the reflective grating 21 and the technical solution of the dummy electrode finger 124 may be flexibly combined and used, referring to fig. 7, fig. 7 is a schematic top view structure of yet another surface acoustic wave resonator provided by the embodiment of the present invention, where the surface acoustic wave resonator includes the dummy electrode finger 124 and the reflective grating 21, no additional piston structure is disposed on the dummy electrode finger 124, and no reflective grating piston structure 22 is disposed on the reflective grating 21; referring to fig. 8, fig. 8 is a schematic top view of a surface acoustic wave resonator according to an embodiment of the present invention, where the surface acoustic wave resonator includes a dummy electrode finger 124 and a reflective grating 21, the dummy electrode finger 124 is provided with a first additional piston structure 19, and the reflective grating 21 is not provided with a reflective grating piston structure 22; referring to fig. 9, fig. 9 is a schematic top view of a surface acoustic wave resonator according to an embodiment of the present invention, where the surface acoustic wave resonator includes a dummy electrode finger 124 and a reflection grating 21, no additional piston structure is disposed on the dummy electrode finger 124, and a reflection grating piston structure 22 is disposed on the reflection grating 21; referring to fig. 10, fig. 10 is a schematic top view of another surface acoustic wave resonator according to an embodiment of the present invention, where the surface acoustic wave resonator includes a dummy electrode finger 124 and a reflection grating 21, the dummy electrode finger 124 is provided with a first additional piston structure 19, and the reflection grating 21 is provided with a reflection grating piston structure 22.

Optionally, in another embodiment of the present invention, referring to fig. 11, fig. 11 is a schematic top view structure of another surface acoustic wave resonator according to an embodiment of the present invention, where when N > 2, the spacing between two adjacent piston structures in the first direction X is different.

Specifically, as shown in fig. 11, in an exemplary embodiment of the present invention, the electrode finger 123 includes a first piston structure 13, a second piston structure 14, and a third piston structure 17 sequentially arranged in a first direction X, where a distance between the first piston structure 13 and the second piston structure 14 is L1, and a distance between the second piston structure 14 and the third piston structure 17 is L2, l1+' l2, so that the suppression effect can be further enhanced while introducing more acoustic impedance discontinuities.

Optionally, in another embodiment of the present invention, referring to fig. 12, fig. 12 is a schematic top view structure of another surface acoustic wave resonator provided in an embodiment of the present invention, referring to fig. 13, fig. 13 is a schematic top view structure of another surface acoustic wave resonator provided in an embodiment of the present invention, in which an orthographic projection pattern of a piston structure on a piezoelectric substrate is polygonal, circular or elliptical, as shown in fig. 12, an orthographic projection pattern of the piston structure and a matching structure on the piezoelectric substrate 11 is trapezoidal in the polygon, as shown in fig. 13, and an orthographic projection pattern of the piston structure and the matching structure on the piezoelectric substrate is elliptical.

Specifically, in the embodiment of the present invention, the orthographic projection pattern of the piston structure on the piezoelectric substrate 11 may not be rectangular, but may be a plurality of orthographic projection patterns including polygons, circles or ellipses, and when the piston structure uses a more complex orthographic projection pattern, more adjustable parameters may be introduced.

Optionally, in another embodiment of the present invention, referring to fig. 14, fig. 14 is a schematic top view structure of another saw resonator according to an embodiment of the present invention, where when N front projection patterns of piston structures on a piezoelectric substrate 11 are the same, front projection areas of at least two piston structures on the piezoelectric substrate 11 are different.

Specifically, as shown in fig. 14, in the embodiment of the present invention, the structure includes a first piston structure 13 and a second piston structure 14, and the orthographic projection patterns of the first piston structure 13 and the second piston structure 14 on the piezoelectric substrate 11 are all rectangles in a polygon, but orthographic projection areas of the first piston structure 13 and the second piston structure 14 on the piezoelectric substrate 11 are different, and this design introduces more acoustic impedance discontinuity, so that a better suppression effect can be achieved through debugging simulation.

Optionally, in another embodiment of the present invention, referring to fig. 15, fig. 15 is a schematic top view structure of another surface acoustic wave resonator according to an embodiment of the present invention, where orthographic projection patterns of at least two piston structures on a piezoelectric substrate 11 are different.

Specifically, as shown in fig. 15, the embodiment of the present invention includes a first piston structure 13 and a second piston structure 14, where the orthographic projection pattern of the first piston structure 13 on the piezoelectric substrate 11 is a trapezoid in a polygon, and the orthographic projection pattern of the second piston structure 14 on the piezoelectric substrate 11 is a rectangle in the polygon, and this design also introduces more acoustic impedance discontinuity, so that a better suppression effect can be achieved by debugging simulation.

Alternatively, in another embodiment of the present invention, referring to fig. 16, fig. 16 is a schematic top view of another surface acoustic wave resonator according to an embodiment of the present invention, where the first bus bar 121 in the interdigital electrode 12 provided in the embodiment of the present invention includes a first bus bar 121a and a first second bus bar 121b that are oppositely disposed in the first direction X, and the length extension directions of the first bus bar 121a and the first second bus bar 121b are the same and all parallel to the second direction Y.

The second bus bar 122 includes a second first bus bar 122a and a second bus bar 122b disposed opposite each other in the first direction X, and the length extension directions of the second first bus bar 122a and the second bus bar 122b are the same and are both parallel to the second direction Y.

Wherein a first ethylene bus bar 121b and a second ethylene bus bar 122b are located between the first and second first bus bars 121a and 122 a.

Specifically, as shown in fig. 16, in the embodiment of the present invention, the interdigital electrode 12 adopts a structure with double bus bars, and this design can improve the reflection and suppression effects of the hybrid mode, and compared with the technical scheme in which the dummy electrode finger 124 is provided, the combination of 1+1 and 2 can be formed, and the occupied area of the saw resonator can be reduced accordingly, and the integration level of the saw device can be improved.

It should be noted that the double bus bar solution as shown in fig. 16 cannot be combined with the solution provided with the dummy electrode finger 124, but can be flexibly combined with the solution provided with the reflective grid 21.

Optionally, in another embodiment of the present invention, referring to fig. 17, fig. 17 is a schematic top view of a surface acoustic wave resonator according to an embodiment of the present invention, referring to fig. 18, and fig. 18 is a schematic top view of a surface acoustic wave resonator according to an embodiment of the present invention; the orthographic projection patterns of the first b bus bar 121b and the second b bus bar 122b on the piezoelectric substrate 11 are straight line patterns, broken line patterns or curve patterns or other shapes or free combinations thereof, so that the suppression effect of the surface acoustic wave resonator is further improved, and adjustable parameters can be increased, so that the technical scheme of the invention can obtain a larger application range.

As shown in fig. 16, the orthographic projection pattern of the first and second b bus bars 121b and 122b on the piezoelectric substrate 11 is a straight line pattern; as shown in fig. 17, the orthographic projection pattern of the first b bus bar 121b and the second b bus bar 122b on the piezoelectric substrate 11 is a broken line pattern; as shown in fig. 18, the orthographic projection pattern of the first and second b bus bars 121b and 122b on the piezoelectric substrate 11 is a curved pattern.

It should be noted that, in some alternative embodiments, the front projection patterns of the first b bus bar 121b and the second b bus bar 122b on the piezoelectric substrate 11 may also be different, for example, the front projection pattern of the first b bus bar 121b on the piezoelectric substrate 11 is a broken line pattern, and the front projection pattern of the second b bus bar 122b on the piezoelectric substrate 11 is a curved line pattern.

The technical effects of the technical scheme of the application are described below in four aspects:

The method comprises the following steps: the design of the double-piston structure or the multi-piston structure introduces additional adjustment parameters such as parameters of distance, length ratio, width ratio with electrode finger strips and the like outside the single-piston structure, so that the optional parameter range of the piston structure for simulation and adjustment is further increased, and finally the application range of the surface acoustic wave resonator is improved.

And two,: the adjustment of the single piston is limited by a process, such as a duty cycle, so that the adjustment range is limited, and the length and width adjustment of at least two piston structures can realize a larger adjustment range under the condition of meeting the duty cycle limit.

And thirdly,: the at least two piston structures can more effectively inhibit the high-order transverse mode by adjusting the length-width ratio and the distance of the at least two piston structures.

Fourth, it is: the design of at least two piston structures is suitable for such as double bus bar structures, and the false finger electrode finger bars are not required, so that the area of the SAW resonator is further reduced.

Referring to fig. 19, fig. 19 is a schematic diagram of a performance curve of a surface wave resonator of a single-piston structure in the prior art, referring to fig. 20, and fig. 20 is a schematic diagram of a performance curve of a surface wave resonator of another single-piston structure in the prior art.

As shown in fig. 19, in the prior art, when the design of a certain surface acoustic wave resonator is simulated, a single piston structure can achieve better transmission performance. However, in the design simulation of another saw resonator as shown in fig. 20, because the process limit of the duty ratio is touched, no further adjustment effect can be achieved by the single piston structure, resulting in a problem that the transmission performance is not ideal.

In an alternative embodiment of the present invention, when n=2, the length of the first piston structure 13 in the first direction X is a, the length of the second piston structure 14 in the first direction X is B, and the distance between the first piston structure 13 and the second piston structure 14 in the first direction X is C.

Referring to fig. 21, fig. 21 is a schematic diagram of a performance curve of a surface acoustic wave resonator with a dual-piston structure according to an embodiment of the present invention, where the length of the first piston structure 13 is as follows: spacing between piston structures: length of the second piston structure 14 = 0.5:0.25:0.5, wherein the spacing between the piston structures refers to the spacing between the first piston structure 13 and the second piston structure 14, namely a: c: b=0.5: 0.25:0.5, the duty cycle of the piston structure is 0.69.

Referring to fig. 22, fig. 22 is a schematic diagram of a performance curve of a surface acoustic wave resonator with another dual-piston structure according to an embodiment of the present invention, where the length of the first piston structure 13 is as follows: spacing between piston structures: length of the second piston structure 14 = 0.5:0.25:0.5, wherein the spacing between the piston structures refers to the spacing between the first piston structure 13 and the second piston structure 14, namely a: c: b=0.5: 0.25:0.5, the duty cycle of the piston structure is 0.72.

Referring to fig. 23, fig. 23 is a schematic diagram of a performance curve of a surface acoustic wave resonator with a dual-piston structure according to an embodiment of the present invention, wherein the length of the first piston structure 13 is as follows: spacing between piston structures: length of the second piston structure 14 = 0.2:0.25:0.2, wherein the spacing between the piston structures refers to the spacing between the first piston structure 13 and the second piston structure 14, namely a: c: b=0.2: 0.25:0.2, the duty cycle of the piston structure is 0.69.

Referring to fig. 24, fig. 24 is a schematic diagram of a performance curve of a surface acoustic wave resonator with a dual-piston structure according to another embodiment of the present invention, where the length of the first piston structure 13 is as follows: spacing between piston structures: length of the second piston structure 14 = 0.5:0.25:0.25, wherein the spacing between the piston structures refers to the spacing between the first piston structure 13 and the second piston structure 14, namely a: c: b=0.5: 0.25:0.25, the duty cycle of the piston structure is 0.69.

In fig. 19, 20, 21, 22, 23, and 24, the horizontal axis is MHz, the vertical axis is dB, and curve 1 is the Y parameter (i.e., admittance-frequency curve), and curve 2 is the real part of the Y parameter (i.e., conductance-frequency curve).

Referring to fig. 25, fig. 25 is a schematic diagram showing a comparison of admittance versus frequency curves in fig. 22-24, and referring to fig. 26, fig. 26 is a schematic diagram showing a comparison of conductance versus frequency curves in fig. 22-24.

The comparison of the four sets of data using the double-piston structure as the simulation result is given above, and it can be known from fig. 21-25 that by changing parameters such as the length ratio of the piston structure, the width ratio of the electrode finger, the distance between the two, etc., the performance of the saw resonator can be very effectively adjusted, wherein when the parameters are adjusted in a smaller range, a sharper resonance peak, a smooth transmission curve, etc. can be realized, which indicates that the adjusting effect is better; meanwhile, compared with the scheme that a single piston structure cannot be effectively regulated due to process limitation, the technical scheme obviously can realize better hybrid mode inhibition effect, reduces energy dissipation and the like caused by a high-order transverse mode, and therefore, the technical scheme has larger and more sensitive parameter adjustment space for the simulation design work of the surface acoustic wave resonator with process size limitation, and further realizes better performance.

Referring to fig. 27, fig. 27 is a schematic diagram showing a performance curve of a surface wave resonator of still another single piston structure in the prior art, wherein the duty cycle of the single piston structure is 0.7.

Referring to fig. 28, fig. 28 is a schematic diagram of a performance curve of a surface wave resonator of yet another single-piston structure in the prior art, wherein the duty cycle of the single-piston structure is 0.71.

Referring to fig. 29, fig. 29 is a schematic diagram of a performance curve of a surface acoustic wave resonator with a dual-piston structure according to an embodiment of the present invention, where the duty cycle of the piston structure is 0.65.

Referring to fig. 30, fig. 30 is a schematic diagram of a performance curve of a surface acoustic wave resonator with a dual-piston structure according to an embodiment of the present invention, where the duty cycle of the piston structure is 0.72.

In fig. 27, 28, 29 and 30, the horizontal axis is MHz, the vertical axis is dB, where curve 1 is the Y parameter (i.e., admittance-frequency curve), and curve 2 is the real part of the Y parameter (i.e., conductance-frequency curve).

As can be seen from fig. 27 to fig. 30, the dual-piston structure adopted in the present technical solution is not a simple superposition of the suppression effect of the single-piston structure, but can make the duty ratio have a larger effective adjustment range (from the experimental data, between 0.64 and 0.78, and under the condition that other conditions are unchanged, the effective range of the single-piston structure is small, where the duty ratio=width/pitch, pitch is half λ), and the single-piston structure is very easy to bring about the problem of forming a double peak at the resonance frequency in the range (for example, the duty ratio of about 0.7 brings about a great influence, and the dual-piston structure obviously has a larger effective duty ratio adjustment range), thereby greatly affecting the resonance performance of the surface acoustic wave resonator.

Optionally, based on the foregoing embodiment of the present invention, in another embodiment of the present invention, a method for manufacturing a surface acoustic wave resonator is further provided, and referring to fig. 31, fig. 31 is a schematic flow chart of a method for manufacturing a surface acoustic wave resonator according to an embodiment of the present invention, where the method for manufacturing a surface acoustic wave resonator according to an embodiment of the present invention includes:

s101: a piezoelectric substrate 11 is provided, the piezoelectric substrate 11 having piezoelectric characteristics.

S102: forming an interdigital electrode 12 on one side of the piezoelectric substrate 11; wherein the interdigital electrode 12 includes a bus bar including a first bus bar 121 and a second bus bar 122 disposed opposite in a first direction X, and an electrode finger 123 on the first bus bar 121 and the second bus bar 122; the length extension directions of the first bus bar 121 and the second bus bar 122 are the same, and both extend along the second direction Y, the first direction X and the second direction Y are parallel to the plane of the piezoelectric substrate 11, and the first direction X and the second direction Y are perpendicular. The electrode finger 123 comprises a first piston structure 13 to an Nth piston structure which are sequentially arranged in a first direction X, N is more than or equal to 2, N is a positive integer, and the first piston structure 13 is positioned at one end of the electrode finger 123 far away from a bus bar correspondingly connected with the electrode finger 123; the electrode finger 123 further includes first to nth matching structures 15 to 15 sequentially arranged in the first direction X, and an ith piston structure is disposed opposite to the ith matching structure in the second direction Y, where i is 1.ltoreq.i.ltoreq.n, and i is a positive integer, and an orthographic pattern of the ith piston structure on the piezoelectric substrate 11 is the same as an orthographic pattern of the ith matching structure on the piezoelectric substrate 11. Wherein the maximum width of the piston structure in the second direction Y is greater than the width of the electrode finger 123 in the second direction Y.

Optionally, based on the foregoing embodiment of the present invention, in another embodiment of the present invention, there is further provided a method for designing a surface acoustic wave resonator, where the method for designing a surface acoustic wave resonator includes:

First, a simulation design model is established.

And secondly, sequentially carrying out multiple rounds of simulation according to the number of the piston structures.

Specifically, when the number of the piston structures is equal to one, determining the minimum length step length alpha, and determining different simulation results corresponding to a plurality of groups of piston structures with different lengths according to a mode that the base length value L of the piston structure in the first direction X is designed in advance and the minimum length step length alpha is sequentially increased and decreased, for example, simulating the piston structure with the length value of L+alpha, the piston structure with the length value of L-alpha, the piston structure with the length value of L+2alpha, the piston structure with the length value of L+5alpha, the piston structure with the length value of L-3alpha and the like respectively so as to determine the simulation results corresponding to different lengths.

When the number of the piston structures is equal to two, in addition to the simulation design of the piston structures with different lengths according to the method, the minimum step length beta of the distance between the two piston structures in the first direction X needs to be determined, and different simulation results corresponding to multiple groups of piston structures with different distances are determined according to a mode of sequentially adding and subtracting multiple groups of minimum step length beta of the basic distance value H between the two piston structures in the first direction X, for example, simulation is performed on the two piston structures with the distance value h+beta, the two piston structures with the distance value h+2beta, the two piston structures with the distance value h+5beta, the two piston structures with the distance value H-3beta and the like, so as to determine the simulation results corresponding to different distances.

It should be noted that when the number of the piston structures is equal to two, the lengths of the two piston structures in the first direction X may be unequal, so that the length differences of the two piston structures in the plurality of groups need to be simulated respectively to determine simulation results corresponding to the different length differences.

When the number of the piston structures is greater than two, the intervals between the two adjacent piston structures in the first direction X may be unequal, so that simulation is required to be performed on the interval differences between the two adjacent piston structures in multiple groups in order to determine simulation results corresponding to the different interval differences, in addition to the simulation design of the piston structures with different lengths, different intervals and different length differences according to the method.

And then, in the simulation result, according to the normalized length dimension, selecting a dimension value which simultaneously contains the optimal sharp resonance peak and the optimal smooth transmission curve and is used as the optimal design dimension of the piston structure.

That is, in the embodiment of the present invention, the performance of the saw resonator may be affected by fine tuning, individually and jointly, a plurality of parameters related to at least two piston structures, such as a length value, a pitch value, a length difference, a pitch difference, a length ratio, a width ratio of electrode fingers, a projected area ratio, and the like, so as to implement at least one of the following preferred performance parameters: higher Q value (quality factor), smoother transmission curve (reduced interference), fine tuning of antiresonant frequency point, electromechanical coupling coefficient (higher/lower), curve fluctuation between resonance point and antiresonant point, etc., that is, a method of performing simulation debugging by setting parameters associated with a plurality of piston structures (parameters not possessed by a conventional single piston structure) respectively, thereby realizing better surface acoustic wave resonator performance.

Optionally, according to the foregoing embodiment of the present invention, in another embodiment of the present invention, there is further provided a filter, which includes the surface acoustic wave resonator described in the foregoing embodiment.

The filter has the same effect as the surface acoustic wave resonator in the above embodiment.

The above description of the surface acoustic wave resonator, the preparation method thereof and the filter provided by the invention applies specific examples to illustrate the principle and the implementation of the invention, and the above examples are only used for helping to understand the method and the core idea of the invention; meanwhile, as those skilled in the art will have variations in the specific embodiments and application scope in accordance with the ideas of the present invention, the present description should not be construed as limiting the present invention in view of the above.

It should be noted that, in the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described as different from other embodiments, and identical and similar parts between the embodiments are all enough to be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant points refer to the description of the method section.

It is further noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include, or is intended to include, elements inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A surface acoustic wave resonator, characterized in that the surface acoustic wave resonator comprises:

a piezoelectric substrate;

2. The surface acoustic wave resonator according to claim 1, characterized in that the interdigital electrode further comprises:

3. The surface acoustic wave resonator according to claim 2, wherein the dummy electrode finger includes first to M-th additional piston structures sequentially arranged in the first direction, M being equal to or greater than 1, and M being a positive integer, the first additional piston structure being located at an end of the dummy electrode finger away from a bus bar to which the dummy electrode finger is correspondingly connected;

4. A surface acoustic wave resonator according to any of claims 1-3, characterized in that the surface acoustic wave resonator further comprises:

5. The surface acoustic wave resonator according to claim 4, characterized in that it further comprises:

And a reflective grating piston structure positioned on the reflective grating.

6. The surface acoustic wave resonator according to claim 1, characterized in that when N > 2, the spacing between two adjacent piston structures in the first direction is different.

7. The saw resonator of claim 1, wherein the orthographic projection pattern of the piston structure on the piezoelectric substrate is polygonal, circular or elliptical.

8. The surface acoustic wave resonator according to claim 1, characterized in that when N of the piston structures have the same orthographic projection pattern on the piezoelectric substrate, orthographic projection areas of at least two of the piston structures on the piezoelectric substrate are different.

9. The saw resonator of claim 1, wherein the orthographic projection patterns of at least two of the piston structures on the piezoelectric substrate are different.

10. The surface acoustic wave resonator according to claim 1, wherein the first bus bar includes a first a bus bar and a first b bus bar that are disposed opposite to each other in the first direction, and the first a bus bar and the first b bus bar have the same length extending direction and are both parallel to the second direction;

11. The surface acoustic wave resonator according to claim 10, characterized in that the orthographic projection pattern of the first and second b bus bars on the piezoelectric substrate is a straight line pattern, a broken line pattern, or a curved line pattern.

12. The surface acoustic wave resonator according to claim 10 or 11, characterized in that the orthographic projection patterns of the first and second b bus bars on the piezoelectric substrate are different.

13. The surface acoustic wave resonator according to claim 1, characterized in that when N = 2, the length of the first piston structure in the first direction is a, the length of the second piston structure in the first direction is B, and the spacing between the first piston structure and the second piston structure in the first direction is C;

14. The preparation method of the surface acoustic wave resonator is characterized by comprising the following steps of:

Providing a piezoelectric substrate;

15. A filter comprising the surface acoustic wave resonator of any one of claims 1 to 13.