Filter and surface acoustic wave resonator

Abstract

The invention provides a filter and a surface acoustic wave resonator, the surface acoustic wave resonator comprises a substrate, a first reflecting grating, a second reflecting grating and a transducer, the substrate comprises a piezoelectric layer; the first and second reflecting gratings are positioned on the upper surface of the piezoelectric layer; the transducer is located on the upper surface of the piezoelectric layer between the first reflecting grating and the second reflecting grating and comprises a first electrode part and a second electrode part, the first electrode part comprises a first finger strip and a first bus bar, the second electrode part comprises a second finger strip and a second bus bar, and the second finger strip, the first bus bar and the second finger strip are arranged in a spaced and crossed mode; the overlapped parts of the adjacent first and second finger strips are used as first apertures, the overlapped parts of all the first and second finger strips in the electrode area are used as second apertures, and two adjacent second apertures and two adjacent first apertures in the electrode area differ by a second preset proportion and a first preset proportion respectively. By improving the structure of the transducer, the difference between the adjacent first apertures and the adjacent second apertures is the first preset proportion and the second preset proportion respectively, and the transverse wave suppression effect of the resonator is improved.

Description

Technical Field

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

[0002] With the development of 5G mobile communication technology, the number of communication frequency bands has increased dramatically, and the frequency spacing between adjacent channels has become increasingly smaller. In mobile communication terminals, to achieve higher-speed signal transmission, more and more filters are being used in the RF front-end. To prevent interference between adjacent frequency bands, filters must have steeper transition bands, lower temperature drift coefficients, and higher quality factors (Q values).

[0003] Compared with traditional surface acoustic wave filters, surface acoustic wave filters based on POI (piezoelectric-on-insulator, also known as piezoelectric single crystal film on insulator) substrates have higher energy utilization efficiency, larger electromechanical coupling coefficient, higher quality factor and lower temperature drift coefficient. Therefore, it is widely used in the field of radio frequency communications. However, while POI substrate technology improves the quality factor of SAW (Surface Acoustic Wave, also known as surface acoustic wave) resonators, it also has problems such as excited transverse modes of acoustic waves, transverse energy leakage and beam deflection. Unlike traditional SAW filters, these transverse wave modes will seriously deteriorate the flatness of the filter passband, reduce the power capacity of the filter, deteriorate the rectangular coefficient of the filter, and at the same time bring about spurious resonance frequencies and reduce the quality factor of the resonator.

[0004] At present, when suppressing the transverse mode, most of the time, a layer of metal is added to the end of the finger of the resonator to reduce the sound speed in this area. Although this method can suppress the transverse mode, it is sensitive to the size and weight of the mass load, and has high requirements for the processing technology, which increases the process cost. Weighting the overlapping area of the interdigital transducer (IDT) fingers can also suppress the transverse wave mode. For example, step weighting is used for the overlapping area of the electrodes, such as Figure 1 The figure shows the top surface structure of the resonator, which includes a first reflector 01, a second reflector 02, an IDT 03, a first finger 031, a first bus bar 032, a first dummy finger 033, a second finger 034, a second bus bar 035, and a second dummy finger 036. However, this method increases the device size and poorly suppresses the shear wave mode, which also reduces the Q value of the resonator. Furthermore, designing the IDT electrodes into an inclined structure can also suppress the shear wave mode, but this increases the area of the transducer electrodes, which is not conducive to reducing the cost and size of the filter.

[0005] Therefore, there is an urgent need to find a surface acoustic wave resonator that can improve the shear wave suppression effect and Q value of the resonator without increasing the device size and process difficulty. Summary of the Invention

[0006] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a filter and a surface acoustic wave resonator for solving the problems of poor Q value and shear wave suppression effect of the resonator in the prior art.

[0007] To achieve the above and other related objectives, the present invention provides a surface acoustic wave resonator, comprising:

[0008] a substrate comprising at least one piezoelectric layer;

[0009] A first reflection grating and a second reflection grating are arranged at intervals along the X direction and are both located on the upper surface of the piezoelectric layer;

[0010] At least one transducer is located on the upper surface of the piezoelectric layer between the first and second reflective gratings, the transducer comprising a first electrode portion and a second electrode portion spaced apart along the Y direction, the first electrode portion comprising a plurality of first fingers spaced apart along the X direction and a first bus bar connected to the first fingers, the second electrode portion comprising a plurality of second fingers spaced apart along the X direction and a second bus bar connected to the second fingers, the first fingers and the second fingers spaced apart and intersecting along the X direction, the transducer being divided into at least three electrode regions adjacent in the X direction, the number of first fingers and second fingers in each electrode region being no less than three, the overlapping portion of the first fingers and second fingers adjacent in the X direction serving as a first aperture, the average of the dimensions of all the first apertures in any electrode region in the Y direction serving as a second aperture for that electrode region, the dimensions of two adjacent first apertures in at least one electrode region differing in the Y direction by a first preset ratio, and the dimensions of the second apertures in two adjacent electrode regions differing in the Y direction by a second preset ratio, the X and Y directions being perpendicular to each other.

[0011] Optionally, a change trend of the size of at least three second apertures arranged in sequence along the X direction in the Y direction is consistent with a change trend of the size of the first aperture in each of the electrode regions in the Y direction.

[0012] Optionally, the size of the first apertures arranged along the X direction in each of the electrode areas in the Y direction tends to first increase and then decrease, and the size of the second apertures in the Y direction tends to first increase and then decrease; or, the size of the first apertures arranged along the X direction in each of the electrode areas in the Y direction tends to first decrease and then increase, and the size of the second apertures in the Y direction tends to first decrease and then increase.

[0013] Optionally, the transducer further comprises at least one electrode region in which the first bus bar and the second bus bar are in corresponding cut-shaped structures.

[0014] Optionally, the transducer further includes at least one electrode region in which the first bus bar and the second bus bar are in a corresponding stepped structure.

[0015] Optionally, the first apertures in the electrode region along the X direction are symmetrical about a center line of the electrode region perpendicular to the X direction.

[0016] Optionally, the magnitude of the change in the size of the first apertures on both sides of at least one first aperture in the same electrode region in the Y direction is different.

[0017] Optionally, among the plurality of second apertures arranged along the X direction, the second apertures on both sides of at least one second aperture have different magnitudes of change in the Y direction.

[0018] Optionally, the first preset ratio ranges from 0.2% to 20%, and the second preset ratio ranges from 0.2% to 20%.

[0019] Optionally, the surface acoustic wave resonator is further provided with a protective layer covering the exposed surface of the transducer, and the upper surface of the protective layer is higher than the upper surface of the transducer by a preset distance.

[0020] The present invention also provides a filter, which includes at least one surface acoustic wave resonator as described above.

[0021] As described above, the filter and surface acoustic wave resonator of the present invention improve the structure of the transducer in the resonator, dividing the transducer into a plurality of electrode areas, wherein the electrode area includes a plurality of first apertures formed by overlapping portions of adjacent first fingers and second fingers, the average value of the sizes of all the first apertures in the Y direction in any electrode area is used as the second aperture of the electrode area, and the sizes of the second apertures in the Y direction of two adjacent electrode areas differ by the second preset ratio, and the sizes of the two adjacent first apertures in the Y direction in each electrode area differ by the first preset ratio, so that the resonator is excited under different electrode areas. The transverse waves produced are smaller, thereby reducing the vector superposition of transverse waves in the resonator, improving the transverse wave suppression effect near the resonant frequency of the resonator, and not increasing the difficulty and cost of the manufacturing process of the resonator, while not changing the size of the resonator and improving the Q value of the resonator; by arranging the cut structure in the transducer of the resonator, the transverse wave suppression effect near the resonant frequency of the resonator can be further improved, and the performance of the resonator can be improved; in addition, by applying the resonator to the filter, the flatness of the passband of the filter and the power capacity of the filter can be improved, and the rectangular coefficient of the filter can be improved, which has high industrial utilization value. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the top surface structure of a surface acoustic wave resonator showing a weighted structure.

[0023] Figure 2 A schematic cross-sectional structure diagram shows a partial structure of a surface acoustic wave resonator of the present invention.

[0024] Figure 3 Another schematic cross-sectional view showing a partial structure of the surface acoustic wave resonator of the present invention

[0025] Figure 4 It shows a schematic diagram of the top surface structure of the surface acoustic wave resonator of the present invention.

[0026] Figure 5 Display as Figure 1 The resonator and Figure 4 Admittance curve of the resonator in Figure 2.

[0027] Figure 6 Display as Figure 1 The resonator and Figure 4 Phase change curve of the resonator.

[0028] Figure 7 It is a schematic diagram showing another top surface structure of the surface acoustic wave resonator of the present invention.

[0029] Figure 8 It is a schematic diagram showing a third top surface structure of the surface acoustic wave resonator of the present invention.

[0030] Figure 9 It is a schematic diagram showing a fourth top surface structure of the surface acoustic wave resonator of the present invention.

[0031] Figure 10 It is a schematic diagram showing a fifth top surface structure of the surface acoustic wave resonator of the present invention.

[0032] Figure 11 It is a schematic diagram showing a sixth top surface structure of the surface acoustic wave resonator of the present invention.

[0033] Figure 12 It is a schematic diagram showing a seventh top surface structure of the surface acoustic wave resonator of the present invention.

[0034] Figure 13-Figure 20 Schematic diagrams showing eight arrangements of the electrode region and the first aperture of the surface acoustic wave resonator of the present invention.

[0035] Figure 21 The diagram shows the arrangement of first fingers and second fingers in a partial area of an interdigital transducer of a surface acoustic wave resonator according to the present invention.

[0036] Explanation of Figure Numbers

[0037] 01 First Reflector

[0038] 02 Second reflector

[0039] 03 Interdigital Transducer

[0040] 031 First Finger

[0041] 032 First Busbar

[0042] 033 First Fake Finger

[0043] 034 Second Finger

[0044] 035 Second bus

[0045] 036 Second Fake Finger

[0046] 1 substrate

[0047] 11 Piezoelectric layer

[0048] 12 Insulation layer

[0049] 13 base

[0050] 2 First reflector

[0051] 3 Second reflector

[0052] 4 Transducers

[0053] 41 first electrode portion

[0054] 411 First Finger

[0055] 412 First Bus

[0056] 413 First Fake Finger

[0057] 42 second electrode portion

[0058] 421 Second Finger

[0059] 422 Second bus

[0060] 423 Second false finger

[0061] 43 electrode area

[0062] 5 Compensation layer

[0063] 51 silicon nitride layer DETAILED DESCRIPTION

[0064] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0065] See also Figures 2 to 21 It should be noted that the diagrams provided in this embodiment are merely schematic illustrations of the basic concept of the present invention. Therefore, the diagrams only show components related to the present invention and are not drawn according to the number, shape, and size of components in actual implementation. In actual implementation, the type, quantity, and proportion of each component may be changed arbitrarily, and the component layout may also be more complex.

[0066] Example 1

[0067] This embodiment provides a surface acoustic wave resonator, such as Figure 2 and Figure 3The figures are respectively a schematic diagram of a cross-sectional structure of the surface acoustic wave resonator and a schematic diagram of another cross-sectional structure of the surface acoustic wave resonator, comprising a substrate 1, a first reflection grating 2, a second reflection grating 3 and a transducer 4, wherein the substrate 1 comprises at least one piezoelectric layer 11; the first reflection grating 2 and the second reflection grating 3 are spaced apart along the X direction, and the first reflection grating 2 and the second reflection grating 3 are both located on the upper surface of the piezoelectric layer 11; at least one transducer 4 is located on the upper surface of the piezoelectric layer 11 between the first reflection grating 2 and the second reflection grating 2, and the transducer 4 comprises a first electrode portion 41 and a second electrode portion 42 spaced apart along the Y direction, the first electrode portion 41 comprises a plurality of first fingers 411 spaced apart along the X direction and a first bus bar 412 connected to the first fingers 411, and the second electrode portion 42 comprises a plurality of first fingers 411 spaced apart along the X direction and a first bus bar 412 connected to the first fingers 411, and the second electrode portion 42 comprises a plurality of first fingers 411 spaced apart along the X direction. A second finger 421 and a second bus bar 422 connected to the second finger 421 are provided, the first finger 411 and the second finger 421 are arranged in an intersecting manner along the X direction, the transducer 4 is divided into at least three electrode areas 43 adjacent to each other in the X direction, the number of the first finger 411 and the second finger 421 in each electrode area 43 is no less than three, the overlapping portion of the first finger 411 and the second finger 421 adjacent to each other in the X direction serves as the first aperture, the average value of the sizes of all the first apertures in any electrode area 43 in the Y direction serves as the second aperture of the electrode area 43, the sizes of two adjacent first apertures in the Y direction in at least one electrode area 43 differ by a first preset ratio, and the sizes of the second apertures in two adjacent electrode areas 43 in the Y direction differ by a second preset ratio, and the X direction and the Y direction are perpendicular to each other.

[0068] Specifically, such as Figure 21 As shown, it is a schematic diagram of the arrangement of the first fingers 411 and the second fingers 421 in a partial area of the interdigital transducer 4, and the first aperture is the overlapping area of the adjacent first fingers 411 and the second fingers 421 in the figure (the dotted areas in the figure). In order to make the various parts of the device clearly illustrated, they are no longer shown one by one in each device figure.

[0069] Specifically, the substrate 1 includes a piezoelectric single crystal film on insulator (POI), a piezoelectric substrate or other suitable substrates.

[0070] Specifically, when the substrate 1 is a piezoelectric single crystal thin film on an insulator, the substrate 1 includes a base 13 , an insulating layer 12 , and the piezoelectric layer 11 stacked in sequence.

[0071] Specifically, while ensuring device performance, the thickness, size and shape of the substrate 1 can be selected according to actual conditions and are not limited here; the thickness, size and shape of the piezoelectric layer 11 can be selected according to actual conditions and are not limited here.

[0072] Specifically, the material of the piezoelectric layer 11 includes lithium tantalate (LiTaO 3 ), lithium niobate (LiNbO 3 ) or other suitable piezoelectric materials.

[0073] Specifically, the first reflection grating 2 and the second reflection grating 3 are used to reflect the surface acoustic wave generated by the transducer 4. After the surface acoustic wave excited by the transducer 4 is incident on the first reflection grating 2 and the second reflection grating 3, the incident wave and the reflected wave are superimposed on each other and propagate in the resonant cavity in the form of a standing wave, concentrating the acoustic wave energy at the center frequency to achieve a cumulative effect, so as to facilitate the output of the transducer 4.

[0074] Specifically, while ensuring device performance, the size, number of fingers, and the size between fingers of the first reflective grating 2 can be selected according to actual conditions and are not restricted here; the size, number of fingers, and the size between fingers of the second reflective grating 3 can be selected according to actual conditions and are not restricted here.

[0075] Specifically, the distance between the first reflection grating 2 and the second reflection grating 3 is an integer multiple of half a wavelength, so that a standing wave is formed between the first reflection grating 2 and the second reflection grating 3 .

[0076] Specifically, the material of the first reflector 2 includes Ti, Cr, Ag, Cu, Mo, Pt, W, Al or other suitable materials; the material of the second reflector 3 includes Ti, Cr, Ag, Cu, Mo, Pt, W, Al or other suitable materials.

[0077] Specifically, the first electrode portion 41 and the second electrode portion 42 have the same size in the X direction, the first fingers 411 in the first electrode portion 41 have the same size in the X direction, the second fingers 421 in the second electrode portion 42 have the same size in the X direction, and the first fingers 411 in the first electrode portion 41 and the second fingers 421 in the second electrode portion 42 have the same size in the X direction.

[0078] Specifically, each of the first fingers 411 and each of the second fingers 421 in the transducer 4 is located on the crest of the standing wave formed between the first reflective grating 2 and the second reflective grating 3, so as to obtain a stronger electrical signal, that is, the distance between the first reflective grating 2 and the transducer 4 is an integer multiple of half the excitation wavelength, and the distance between the second reflective grating 3 and the transducer 4 is an integer multiple of half the excitation wavelength.

[0079] Specifically, the size of the first electrode portion 41 and the second electrode portion 42 in the X direction is the same as the size of the transducer 4. While ensuring the performance of the device, the size and thickness of the transducer 4 can be selected according to actual conditions and are not limited here.

[0080] Specifically, the material of the transducer 4 includes Ti, Cr, Ag, Cu, Mo, Pt, W, Al or other suitable materials.

[0081] Specifically, while ensuring device performance, the width of the first fingers can be selected based on actual conditions and is not limited here. The length of each first finger can be selected based on actual conditions and is not limited here. The width here refers to the dimension in the X direction, and the length here refers to the dimension in the Y direction.

[0082] Specifically, the first bus bar and the second bus bar are used for input or output signals of the resonator.

[0083] As an example, Figure 4 、 Figure 7 and Figure 8 As shown, they are respectively a schematic diagram of the top surface structure of the resonator, another schematic diagram of the top surface structure of the resonator, and a schematic diagram of the third top surface structure of the resonator. The first bus bar 412 is in the shape of a straight bar extending along the X direction, and the second bus bar 422 is in the shape of a straight bar extending along the X direction.

[0084] Specifically, while ensuring the performance of the resonator, the first bus bar 412 in the transducer 4 can also be partially straight and partially non-straight, and the second bus bar 422 and the first bus bar 412 are symmetrical about the midline of the transducer 4 perpendicular to the Y direction.

[0085] As an example, Figure 9 、 Figure 10 and Figure 11As shown, there are respectively a schematic diagram of the fourth top surface structure of the resonator, a schematic diagram of the fifth top surface structure of the resonator, and a schematic diagram of the sixth top surface structure of the resonator. The transducer 4 further includes at least one electrode region 43 in which the first bus bar 412 and the second bus bar 422 have corresponding cut-out structures. The cut-out structure here means that the surface where the first bus bar 412 (the second bus bar 422) is electrically connected to the first finger 411 (the second finger 421) is not parallel to the plane opposite to the plane and is inclined. The bus bars in the electrode region 43 are trapezoidal in a view perpendicular to the XY plane. The cut-out structures in the first bus bar 412 and the second bus bar 422 are symmetrical about the midline between the first bus bar 412 and the second bus bar 422 (i.e., the midline parallel to the X direction).

[0086] Specifically, while ensuring the performance of the resonator, the position and size of the cut structure in the X direction can be selected according to actual conditions and are not limited here.

[0087] As an example, Figure 12 FIG. 4 shows a schematic diagram of a seventh top surface structure of the resonator. The transducer 4 further includes at least one electrode region 43 in which the first bus bar 412 and the second bus bar 422 have corresponding stepped structures. The stepped structure herein refers to a stepped undulation on a surface where the first bus bar 412 (the second bus bar 422) is electrically connected to the first finger 411 (the second finger 421). This portion of the bus bars in the electrode region 43 has a stepped shape when viewed perpendicular to the XY plane. The stepped structures of the first bus bar 412 and the second bus bar 422 are symmetrical about the midline between the first bus bar 412 and the second bus bar 422 (i.e., the midline parallel to the X direction).

[0088] Specifically, while ensuring the performance of the resonator, the position and size of the stepped structure can be selected according to actual conditions and are not limited here.

[0089] As an example, the first electrode portion 41 further includes a first dummy finger 413 connected to the first bus bar 412, and the second electrode portion 42 further includes a second dummy finger 423 connected to the second bus bar 422. The first dummy finger 413 is located between two adjacent first fingers 411 and is spaced apart from the first fingers 411 on both sides of the X direction by a preset distance. The first dummy finger 413 corresponds one-to-one with the second fingers 421 and is spaced apart from the second fingers 421 in the Y direction by a preset distance. The second dummy finger 423 is located between two adjacent second fingers 421 and is spaced apart from the second fingers 421 on both sides of the X direction by a preset distance. The second dummy finger 423 corresponds one-to-one with the first fingers 411 and is spaced apart from the first fingers 411 in the Y direction by a preset distance.

[0090] Specifically, while ensuring resonator performance, the dimensions of the first dummy finger 413 in the Y and X directions can be selected based on actual conditions and are not limited here. The dimensions of the second dummy finger 423 in the Y and X directions can be selected based on actual conditions and are not limited here. In this embodiment, the dimensions of the first dummy finger 413 and the second dummy finger 423 in the X direction are the same as the dimensions of the second finger 421 and the first finger 411 in the X direction, respectively.

[0091] Specifically, the first dummy finger 413 is made of Ti, Cr, Ag, Cu, Mo, Pt, W, Al, or other suitable materials; the second dummy finger 423 is made of Ti, Cr, Ag, Cu, Mo, Pt, W, Al, or other suitable materials. In this embodiment, the first dummy finger 413 is made of the same material as the first finger 411 and the first bus bar 412, and the second dummy finger 423 is made of the same material as the second finger 421 and the second bus bar 422.

[0092] Specifically, such as Figure 13-20 As shown, there are 8 different arrangement diagrams of the electrode area 43 and the first aperture 411. Under the premise of ensuring the resonator performance and the number of the electrode areas 43 being no less than 3, the number of the electrode areas 43 divided in the transducer 4 can be selected according to actual conditions and is no longer restricted here.

[0093] Specifically, the number of the first apertures in the electrode area 43 is the same as the number of the first fingers 411 and the second fingers 421. While ensuring the resonator performance and the number of the first apertures in the electrode area 43 being no less than 3, the number of the first apertures in the electrode area 43 can be selected according to actual conditions and is no longer restricted here.

[0094] As an example, each of the first apertures in the electrode region 43 along the X direction is symmetrical about a center line of the electrode region 43 perpendicular to the X direction. That is, when a plurality of first apertures are provided in the electrode region 43, the first apertures in the electrode region 43 are symmetrical about a center line of the electrode region 43 perpendicular to the X direction.

[0095] As an example, the magnitude of the change in the size of at least one first aperture in the same electrode area 43 on both sides of the first aperture along the X direction is different. For example, there are three first apertures arranged in sequence along the X direction in the electrode area 43, and the size of the first first aperture in the Y direction is 5% larger than that of the second first aperture (5% of the size of the second first aperture in the Y direction), and the size of the third first aperture in the Y direction can be 1% larger than that of the second first aperture (1% of the size of the second first aperture in the Y direction).

[0096] As an example, the change trend of the size of the first apertures arranged along the X direction in the same electrode area 43 in the Y direction is the same, that is, the sizes of the multiple first apertures arranged in sequence along the X direction in the electrode area 43 in the Y direction can increase or decrease in sequence by the first preset ratio.

[0097] As an example, the size change trend of the first apertures arranged along the X direction in the Y direction in at least two adjacent electrode areas 43 is the same, that is, in the transducer, the size of the first apertures arranged along the X direction in the Y direction in at least two adjacent electrode areas 43 changes synchronously (synchronously increases, synchronously decreases) in sequence.

[0098] As an example, the second apertures arranged along the X direction are symmetrical about the midline of the transducer 4 perpendicular to the X direction, that is, the transducer 4 composed of the plurality of electrode areas 43 arranged along the X direction, and the second apertures arranged along the X direction are symmetrical about the midline of the transducer 4 perpendicular to the X direction.

[0099] As an example, among the multiple second apertures arranged along the X direction, the second apertures on both sides of at least one second aperture have the same trend of change in size in the Y direction, that is, the three second apertures in the transducer 4 are arranged successively in sequence along the X direction, and the sizes of the three second apertures in the Y direction show an increasing or decreasing trend. For example, the size of the first second aperture in the Y direction is increased by the second preset proportion relative to the size of the second second aperture, and the size of the third second aperture in the Y direction is also increased by the second preset proportion relative to the size of the second second aperture.

[0100] As an example, among the multiple second apertures arranged along the X direction, the magnitude of the change in the size of the second apertures on both sides of at least one second aperture in the Y direction is different. For example, the magnitude of the change here refers to the ratio of increase or decrease. For example, among the three electrode areas 43 arranged sequentially along the X direction, the second aperture of the second electrode area 43 is 5% larger in the Y direction than the second aperture of the first electrode area 43 (the size of the second aperture of the second electrode area 43 in the Y direction is increased by 5%), and the second aperture of the third electrode area 43 is 2% larger in the Y direction than the second aperture of the second electrode area 43 (the size of the second aperture of the second electrode area 43 in the Y direction is increased by 2%).

[0101] As an example, a change trend of the size of at least three second apertures arranged in sequence along the X direction in the Y direction is consistent with a change trend of the size of the first aperture in each electrode area 43 in the Y direction.

[0102] As an example, the change trend of the size of at least three second apertures arranged in sequence along the X direction in the Y direction is consistent with the change trend of the size of the first aperture in each electrode area 43 in the Y direction, which can be understood as:

[0103] The size of the first apertures arranged along the X direction in each electrode region in the Y direction tends to increase first and then decrease, and the size of the second apertures in the Y direction tends to increase first and then decrease, such as Figure 13 、 Figure 14 、 Figure 17 and Figure 20 As shown, Figure 13 and Figure 14 The size of the first aperture in each electrode region 41 in the Y direction shows a trend of first increasing and then decreasing, and the size of the second aperture in the entire IDT 4 in the Y direction also shows a trend of first increasing and then decreasing. Figure 17 and Figure 20 The size of the first hole in each of the electrode areas 41 in the Y direction tends to first increase and then decrease. In the entire interdigital transducer 4, the size of the second aperture in the Y direction changes periodically, and the size of the second aperture in the Y direction in each period tends to first increase and then decrease.

[0104] As an example, the change trend of the size of at least three second apertures arranged in sequence along the X direction in the Y direction is consistent with the change trend of the size of the first aperture in each electrode area 43 in the Y direction, which can also be understood as:

[0105] The size of the first apertures arranged along the X direction in each electrode region in the Y direction shows a trend of first decreasing and then increasing, and the size of the second apertures in the Y direction shows a trend of first decreasing and then increasing, such as Figure 15 、 Figure 16 、 Figure 18 and Figure 19 As shown, Figure 15 and Figure 16 The size of the first aperture in each electrode region 41 in the Y direction shows a trend of first decreasing and then increasing, and the size of the second aperture in the entire IDT 4 in the Y direction also shows a trend of first decreasing and then increasing. Figure 18 and Figure 19 The size of the first aperture in each electrode area 41 in the Y direction tends to first increase and then decrease. In the entire interdigital transducer 4, the size of the second aperture in the Y direction changes periodically, and the size of the second aperture in the Y direction in each period tends to first decrease and then increase.

[0106] As an example, three electrode areas are sequentially arranged along the X direction, and the size of the second aperture in the Y direction shows a trend of first increasing and then decreasing. If this is defined as a variation interval, then when there are multiple electrode areas 43, the multiple electrode areas 43 can include multiple variation intervals, such as Figure 17 、 Figure 18 、 Figure 19 shown.

[0107] As an example, the first preset ratio ranges from 0.2% to 20%, and the second preset ratio ranges from 0.2% to 20%.

[0108] Specifically, the values of the first preset ratio of the difference in the Y direction between any two adjacent first apertures in each electrode area 43 may be the same or different; and the values of the second preset ratio of the difference in the Y direction between any two adjacent second apertures in all the second apertures may be the same or different.

[0109] As an example, the surface acoustic wave resonator is further provided with a protective layer 5 covering the exposed surface of the transducer, and the upper surface of the protective layer 5 is higher than the upper surface of the transducer by a preset distance.

[0110] Specifically, while ensuring the performance of the resonator, the thickness of the protective layer 5 can be selected according to actual conditions and is not limited here.

[0111] Specifically, the protective layer 5 can reduce the temperature coefficient of the resonator and improve the temperature characteristics of the device. The material of the protective layer 5 includes silicon oxide or other materials suitable for reducing the temperature coefficient of the resonator.

[0112] Specifically, silicon oxide is used as the protective layer 5 , and a silicon nitride layer 51 with a preset thickness may be formed on the upper surface of the protective layer 5 to further protect the resonator.

[0113] Specifically, such as Figure 5 and Figure 6 As shown, they are Figure 1 The resonator and Figure 4 Admittance curve of the resonator and Figure 1 The resonator and Figure 4 Phase change curve of the resonator in FIG, wherein the width of the first finger and the second finger, the distance between the first finger and the second finger, and the number of the first finger and the second finger in the two resonators are the same, and the structure of the resonator and the partition of the transducer are also the same, Figure 5 The solid line is Figure 4 The admittance curve of the resonator in the figure is shown in the dashed line. Figure 1 The admittance curve of the resonator, Figure 6 The solid line is Figure 4 The phase change curve of the resonator in the dotted line is Figure 1 From the phase change curve of the resonator in the admittance and phase change diagram, it can be seen that the transducer 4 is divided into three electrode areas 43, and the sizes of the adjacent first apertures in the Y direction in each electrode area 43 differ (increase or decrease) by the first preset ratio. On the right side of the resonant frequency near the resonator, the burr of the solid line is significantly smaller and weaker than the burr of the dotted line, indicating that the shear wave near the resonant frequency of the resonator is suppressed.

[0114] Specifically, by dividing the transducer 4 into at least three electrode areas 43, and the electrode area 43 includes at least three first apertures, the sizes of two adjacent first apertures in the Y direction differ by the first preset ratio, the sizes of two adjacent second apertures in the Y direction differ by the second preset ratio, the size of the first aperture in the Y direction is greater than zero, the size of the second aperture in the Y direction is greater than zero, and the acoustic aperture value of the transducer is not zero, so that the shear waves excited by the resonator in different electrode areas 43 are smaller, and at the same time, the vector superposition of the shear wave mode can be reduced, so that the shear wave suppression effect near the resonant frequency of the resonator is improved.

[0115] Specifically, by adding and changing the structures of the first bus bar 412 and the second bus bar 422 in the transducer 43 and adding a cut-type structure or a stepped structure to the transducer 4, the shear waves near the resonant frequency of the resonator can be further suppressed.

[0116] Specifically, due to the different sizes of the first apertures in the electrode region 43 in the Y direction, the transverse modes excited by the first aperture step fractal have less superposition of the same transverse wave amplitude compared to the uniformly weighted mode, thereby achieving the effect of reducing the transverse wave amplitude. Ultimately, the resonator response exhibits a smoother passband response.

[0117] Specifically, by improving the weighting method of the first aperture in the electrode area 43 in the transducer 4, the transverse mode suppression effect of the resonator and the Q value of the resonator are improved. At the same time, there is no need to change the shape and width of the first finger 411 and the second finger 421, which improves the performance of the resonator without affecting the size of the resonator. In addition, since only the weighting method of the first aperture is changed, the difficulty and cost of manufacturing the resonator will not increase.

[0118] The surface acoustic wave resonator of this embodiment improves the structure of the transducer 4, divides the transducer 4 into a plurality of adjacent electrode areas 43 with different second apertures, and the size difference in the Y direction between two adjacent first apertures in the electrode area 43 is the first preset ratio, and the size difference in the Y direction between two adjacent second apertures is the second preset ratio, so that the shear wave excited by the transducer 4 in the resonator is smaller, the vector superposition of the shear wave is reduced, and the shear wave suppression effect near the resonant frequency of the resonator is improved. At the same time, it does not affect the difficulty and cost of manufacturing the resonator, and improves the Q value of the resonator. By adding the cut structure or the stepped structure to the transducer, the shear wave suppression effect near the resonant frequency of the resonator can be further improved.

[0119] Example 2

[0120] This embodiment provides a filter, which includes at least one surface acoustic wave resonator as described in the first embodiment.

[0121] Specifically, the surface acoustic wave resonator in the filter improves the flatness of the filter passband and the power capacity of the filter, improves the squareness coefficient of the filter, and enhances the Q value of the filter by adopting the surface acoustic wave resonator described in Example 1.

[0122] Specifically, the surface acoustic wave resonator in the filter adopts the surface acoustic wave resonator described in Example 1, which improves the performance of the device without increasing the difficulty of the device manufacturing process and the increase in manufacturing cost, and does not affect the size of the device.

[0123] The filter of this embodiment improves the flatness of the filter passband and the power capacity of the filter by adopting the surface acoustic wave resonator described in Example 1, improves the rectangular coefficient of the filter, and increases the Q value of the filter, while not increasing the difficulty and cost of manufacturing the device and not affecting the size of the device.

[0124] In summary, the filter and surface acoustic wave resonator of the present invention improve the structure of the surface acoustic wave resonator, divide the transducer in the resonator into multiple electrode areas with different second aperture sizes in the Y direction, the sizes of adjacent second apertures in the Y direction differ by a second preset ratio, the overlapping parts of adjacent first fingers and second fingers in the electrode area serve as the first aperture, the electrode area includes multiple first apertures, the sizes of adjacent first apertures in the Y direction differ by a first preset ratio, so that the shear waves excited by the resonator under different electrode areas are smaller, thereby reducing the vector superposition of shear waves and improving the shear wave suppression effect near the resonant frequency of the resonator, while not increasing the difficulty and cost of manufacturing the resonator, improving the Q value of the resonator, and not affecting the size of the device; setting a cut structure or a stepped structure in the transducer of the resonator can further suppress the shear waves near the resonant frequency of the resonator and improve the Q value of the resonator; in addition, applying the surface acoustic wave resonator to the filter can improve the flatness of the filter passband and the power capacity of the filter, and improve the rectangular coefficient of the filter. Therefore, the present invention effectively overcomes the various shortcomings of the prior art and has high industrial utilization value.

[0125] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A surface acoustic wave resonator, characterized in that: include: a substrate comprising at least one piezoelectric layer; A first reflection grating and a second reflection grating are arranged at intervals along the X direction and are both located on the upper surface of the piezoelectric layer; At least one transducer is located on the upper surface of the piezoelectric layer between the first and second reflective gratings, the transducer comprising a first electrode portion and a second electrode portion spaced apart along the Y direction, the first electrode portion comprising a plurality of first fingers spaced apart along the X direction and a first bus bar connected to the first fingers, the second electrode portion comprising a plurality of second fingers spaced apart along the X direction and a second bus bar connected to the second fingers, the first fingers and the second fingers spaced apart and intersecting along the X direction, the transducer being divided into at least three electrode regions adjacent in the X direction, the number of first fingers and second fingers in each electrode region being no less than three, the overlapping portion of the first fingers and second fingers adjacent in the X direction serving as a first aperture, the average of the dimensions of all the first apertures in any electrode region in the Y direction serving as a second aperture for that electrode region, the dimensions of two adjacent first apertures in at least one electrode region differing in the Y direction by a first preset ratio, and the dimensions of the second apertures in two adjacent electrode regions differing in the Y direction by a second preset ratio, the X and Y directions being perpendicular to each other.

2. The surface acoustic wave resonator according to claim 1, wherein: A change trend of the sizes of at least three second apertures arranged in sequence along the X direction in the Y direction is consistent with a change trend of the size of the first aperture in each of the electrode regions in the Y direction.

3. The surface acoustic wave resonator according to claim 2, wherein: The size of the first apertures arranged along the X direction in each of the electrode regions in the Y direction tends to first increase and then decrease, and the size of the second apertures in the Y direction tends to first increase and then decrease; or the size of the first apertures arranged along the X direction in each of the electrode regions in the Y direction tends to first decrease and then increase, and the size of the second apertures in the Y direction tends to first decrease and then increase.

4. The surface acoustic wave resonator according to claim 1, wherein: The transducer further includes at least one electrode region in which the first bus bar and the second bus bar are in corresponding cut-shaped structures.

5. The surface acoustic wave resonator according to claim 1, wherein: The transducer further includes at least one electrode region wherein the first bus bar and the second bus bar are in corresponding stepped structures.

6. The surface acoustic wave resonator according to claim 1 or 2, characterized in that: The first apertures in the electrode region along the X direction are symmetrical about a center line of the electrode region perpendicular to the X direction.

7. The surface acoustic wave resonator according to claim 1 or 2, characterized in that: The change amplitudes of at least one first aperture on two sides along the X direction of the same electrode region are different.

8. The surface acoustic wave resonator according to claim 1 or 2, characterized in that: Among the plurality of second apertures arranged along the X direction, the variation ranges of the second apertures on both sides of at least one second aperture are different.

9. The surface acoustic wave resonator according to claim 1, wherein: The first preset ratio ranges from 0.2% to 20%, and the second preset ratio ranges from 0.2% to 20%.

10. The surface acoustic wave resonator according to claim 1, wherein: The surface acoustic wave resonator is further provided with a protective layer covering the exposed surface of the transducer, and the upper surface of the protective layer is higher than the upper surface of the transducer by a preset distance.

11. A filter, characterized in that: The filter comprises at least one surface acoustic wave resonator according to any one of claims 1 to 10.

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