A surface acoustic wave resonator and radio frequency filter

Abstract

The embodiment of the present invention provides a surface acoustic wave resonator and a radio frequency filter, the surface acoustic wave resonator comprising: a substrate; a piezoelectric layer located on the substrate; an electrode layer, the electrode layer being located on a side of the piezoelectric layer away from the substrate; the electrode layer comprising an interdigital transducer, the interdigital transducer comprising: a first bus bar and a first electrode finger and a first dummy electrode finger alternately connected to the first bus bar; a second bus bar and a second electrode finger and a second dummy electrode finger alternately connected to the second bus bar; the first electrode finger and the second dummy electrode finger are arranged oppositely, with a first gap between the first electrode finger and the second dummy electrode, and the second electrode finger and the first dummy electrode are arranged oppositely, with a second gap between the second electrode finger and the first dummy electrode. The surface acoustic wave resonator and the radio frequency filter provided by the embodiment of the present invention can effectively suppress the transverse mode ripples.

Description

Technical Field

[0001] The invention relates to the field of communications, and in particular to a surface acoustic wave resonator and a radio frequency filter. Background Art

[0002] As communication technology develops from 2G to 5G, the number of communication frequency bands has gradually increased (from 4 frequency bands in 2G to more than 50 frequency bands in 5G). In order to improve the compatibility of smartphones with different communication standards, the amount of filters required for 5G smartphones will increase significantly, driving large-scale growth in the filter market. The RF filter currently widely used in wireless communication terminals is the surface acoustic wave filter, which is responsible for receiving and transmitting RF signals in the channel and outputting signals of specific frequencies from the input multiple RF signals. At the same time, with the continuous development of mobile communication technology and the modularization of RF front-ends, the market demand for filters tends to be more complex, high-end, and miniaturized.

[0003] Surface acoustic wave devices based on single-crystal piezoelectric lithium tantalate substrates have been widely used in RF filters. However, due to the limitations of the Q value and high-frequency temperature coefficient of single-crystal piezoelectric materials, they are difficult to meet the requirements of RF front-end chips.

[0004] In actual applications, surface acoustic wave resonators and RF filters that still use traditional designs will have strong transverse mode ripples and serious passband noise, leading to the deterioration of overall device performance. Summary of the invention

[0005] The surface acoustic wave resonator and radio frequency filter provided by the embodiments of the present invention can effectively suppress transverse mode ripples.

[0006] In a first aspect, an embodiment of the present invention provides a surface acoustic wave resonator, the surface acoustic wave resonator comprising: a substrate;

[0007] a piezoelectric layer located on the substrate;

[0008] an electrode layer, the electrode layer being located on a side of the piezoelectric layer away from the substrate;

[0009] The electrode layer includes an interdigital transducer, and the interdigital transducer includes: a first bus bar and first electrode fingers and first dummy electrode fingers alternately connected to the first bus bar; a second bus bar and second electrode fingers and second dummy electrode fingers alternately connected to the second bus bar; the first electrode finger and the second dummy electrode finger are arranged opposite to each other, and a first gap is formed between the first electrode finger and the second dummy electrode, and the second electrode finger and the first dummy electrode are arranged opposite to each other, and a second gap is formed between the second electrode finger and the first dummy electrode;

[0010] The first bus bar includes a first sub-bus bar and a second sub-bus bar, and the first sub-bus bar and the second sub-bus bar are connected;

[0011] The second bus bar includes a third sub-bus bar and a fourth sub-bus bar, and the third sub-bus bar is connected to the fourth sub-bus bar; the first gap includes a first sub-gap and a second sub-gap, and the second gap includes a third sub-gap and a fourth sub-gap, the first sub-gap and the third sub-gap are located between the first sub-bus bar and the third sub-bus bar, and the second sub-gap and the fourth sub-gap are located between the second sub-bus bar and the fourth sub-bus bar;

[0012] Wherein, each of the first sub-gaps is arranged along the first direction, each of the third sub-gaps is arranged along the first direction, each of the second sub-gaps is arranged along the second direction, and each of the fourth sub-gaps is arranged along the second direction;

[0013] The angle between the first direction and the third direction is in the range of 2° to 15°, the angle between the second direction and the third direction is in the range of 2° to 15°, and in the direction parallel to the plane of the piezoelectric layer, the third direction is perpendicular to the length direction of the first electrode finger.

[0014] Optionally, the first sub-bus bar is parallel to the third sub-bus bar, the length direction of the first sub-bus bar is parallel to the first direction, the second sub-bus bar is parallel to the fourth sub-bus bar, and the length direction of the second sub-bus bar is parallel to the second direction.

[0015] Optionally, a first electrode finger is disposed between adjacent first gaps, and a second electrode finger is disposed between adjacent second gaps.

[0016] Optionally, the first electrode finger and the second electrode finger each include a main body and a terminal integrally connected to the main body, the terminal of the first electrode finger is located on a side of the main body of the first electrode finger away from the first bus bar, and the terminal of the second electrode finger is located on a side of the main body of the second electrode finger away from the second bus bar;

[0017] The first dummy electrode finger and the second dummy electrode finger each include a main body and a terminal integrally connected to the main body, the terminal of the first dummy electrode finger is located on a side of the main body of the first dummy electrode finger away from the first bus bar, and the terminal of the second dummy electrode finger is located on a side of the main body of the second dummy electrode finger away from the second bus bar;

[0018] In the third direction, the width of the end head is greater than the width of the main body.

[0019] Optionally, in the third direction, the width of the end is 1.2 to 1.8 times the width of the main body.

[0020] Optionally, the end of the first electrode finger is arranged opposite to the end of the second dummy electrode finger;

[0021] The end of the second electrode finger is arranged opposite to the end of the first dummy electrode finger.

[0022] Optionally, the electrode layer further includes a reflective grid structure;

[0023] The reflective grid structure includes a third bus bar, a fourth bus bar and a reflective grid; the third bus bar is arranged in parallel with the fourth bus bar;

[0024] The first end of the reflective grid is connected to the third bus bar, and the second end of the reflective grid is connected to the fourth bus bar;

[0025] A reflective grating structure is provided on a side of the first sub-bus bar away from the second sub-bus bar, and a reflective grating structure is provided on a side of the second sub-bus bar away from the first sub-bus bar;

[0026] Wherein, the third bus bar is perpendicular to the reflector and the angle between the third bus bar and the first direction is in the range of 2 to 15°;

[0027] Or the angle between the third bus bar and the reflective grid is in the range of 75° to 88° and the length direction of the third bus bar in the reflective grid structure located on the side of the first sub-bus bar away from the second sub-bus bar is parallel to the first direction, and the length direction of the third bus bar in the reflective grid structure located on the side of the second sub-bus bar away from the first sub-bus bar is parallel to the second direction.

[0028] Optionally, the piezoelectric material of the piezoelectric layer includes a positioning edge, and the positioning edge of the piezoelectric material is parallel to the first electrode finger, the second electrode finger, the first dummy electrode finger, and the second dummy electrode finger.

[0029] Optionally, the surface acoustic wave resonator provided by the embodiment of the present invention further includes an energy trap layer, wherein the energy trap layer is located between the substrate and the piezoelectric layer;

[0030] A first dielectric layer, wherein the first dielectric layer is located between the energy trap layer and the piezoelectric layer;

[0031] A second dielectric layer is located on a side of the electrode layer away from the piezoelectric layer and covers the electrode layer.

[0032] In a second aspect, an embodiment of the present invention provides a radio frequency filter, which includes the surface acoustic wave resonator provided by any embodiment of the present invention.

[0033] The surface acoustic wave resonator provided by the embodiment of the present invention suppresses the transverse mode ripples of the surface acoustic wave resonator by changing the angle between the first direction and the third direction and the angle between the second direction and the third direction. When the angle between the first direction and the third direction is in the range of 2° to 15° and the angle between the second direction and the third direction is in the range of 2° to 15°, the transverse mode ripples can be effectively suppressed. The surface acoustic wave resonator provided by the embodiment of the present invention can effectively suppress the transverse mode ripples. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A schematic structural diagram of a surface acoustic wave resonator provided by an embodiment of the present invention;

[0035] Figure 2 A schematic structural diagram of an interdigital transducer provided in an embodiment of the present invention;

[0036] Figure 3 A schematic structural diagram of another interdigital transducer provided in an embodiment of the present invention;

[0037] Figure 4 A schematic structural diagram of another interdigital transducer provided in an embodiment of the present invention;

[0038] Figure 5 A schematic structural diagram of another interdigital transducer provided in an embodiment of the present invention;

[0039] Figure 6 A schematic structural diagram of another interdigital transducer provided in an embodiment of the present invention;

[0040] Figure 7 A schematic diagram of the admittance measurement results of a surface acoustic wave resonator in the prior art and a surface acoustic wave resonator provided by an embodiment of the present invention;

[0041] Figure 8 A schematic diagram of measured results of the real part of the admittance of a surface acoustic wave resonator provided by an embodiment of the present invention when the angles between the first direction and the third direction are different;

[0042] Fig. 9 A schematic diagram of measured results of the admittance amplitude of the surface acoustic wave resonator provided by an embodiment of the present invention when the angles between the first direction and the third direction are different;

[0043] Fig.10 A schematic structural diagram of another interdigital transducer provided in an embodiment of the present invention;

[0044] Fig.11A schematic diagram of a top view structure of an electrode layer provided in an embodiment of the present invention;

[0045] Fig.12 A schematic diagram of a top view structure of another electrode layer provided in an embodiment of the present invention;

[0046] Fig.13 A schematic diagram of a top view structure of another electrode layer provided in an embodiment of the present invention;

[0047] Fig.14 A schematic diagram of a top view structure of another electrode layer provided in an embodiment of the present invention;

[0048] Fig.15 A schematic diagram of a top view structure of another electrode layer provided in an embodiment of the present invention;

[0049] Fig.16 A schematic diagram of a top view of a surface acoustic wave resonator provided by an embodiment of the present invention;

[0050] Fig.17 The figure is a schematic diagram of the measured results of the insertion loss of the radio frequency filter in the prior art and the radio frequency filter provided by the embodiment of the present invention. DETAILED DESCRIPTION

[0051] The embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the embodiments of the present invention, rather than to limit the embodiments of the present invention. It is also necessary to explain that, for ease of description, only parts related to the embodiments of the present invention are shown in the accompanying drawings, rather than all structures.

[0052] Figure 1 A schematic diagram of the structure of a surface acoustic wave resonator provided by an embodiment of the present invention, Figure 2 A schematic diagram of the structure of an interdigital transducer provided in an embodiment of the present invention, referring to Figure 1 and Figure 2The surface acoustic wave resonator provided by the embodiment of the present invention comprises: a substrate 110; a piezoelectric layer 120 located on the substrate 110; an electrode layer 130, wherein the electrode layer 130 is located on a side of the piezoelectric layer 120 away from the substrate 110; the electrode layer 130 comprises an interdigital transducer 131, wherein the interdigital transducer 131 comprises: a first bus bar 10 and first electrode fingers 20 and first dummy electrode fingers 30 alternately connected to the first bus bar 10; a second bus bar 40 and first dummy electrode fingers alternately connected to the second bus bar 40; The first electrode finger 20 and the second dummy electrode finger 60 are arranged opposite to each other, and a first gap 70 is formed between the first electrode finger 20 and the second dummy electrode finger 60; the second electrode finger 50 and the first dummy electrode finger 30 are arranged opposite to each other, and a second gap 80 is formed between the second electrode finger 50 and the first dummy electrode 30; the first bus bar 10 includes a first sub-bus bar 11 and a second sub-bus bar 12, and the first sub-bus bar 11 and the second sub-bus bar 12 are connected The second bus bar 40 includes a third sub-bus bar 41 and a fourth sub-bus bar 42, and the third sub-bus bar 41 is connected to the fourth sub-bus bar 42; the first gap 70 includes a first sub-gap 71 and a second sub-gap 72, and the second gap 80 includes a third sub-gap 81 and a fourth sub-gap 82, and the first sub-gap 71 and the third sub-gap 81 are located between the first sub-bus bar 11 and the third sub-bus bar 41, and the second sub-gap 72 and the fourth sub-gap 82 are located between the second sub-bus bar 12 and the fourth sub-bus bar between the flow bars 42; wherein, each first sub-gap 71 is arranged along the first direction x, each third sub-gap 81 is arranged along the first direction x, each second sub-gap 72 is arranged along the second direction y, and each fourth sub-gap 82 is arranged along the second direction y; the angle β between the first direction x and the third direction z is in the range of 2° to 15°, the angle θ between the second direction y and the third direction z is in the range of 2° to 15°, and in the direction parallel to the plane of the piezoelectric layer, the third direction z is perpendicular to the length direction of the first electrode finger 20.

[0053] Specifically, the material of the substrate 110 may be high-resistance silicon, which may be P-type high-resistance silicon or N-type high-resistance silicon, and the resistivity of the high-resistance silicon is greater than 2000Ω·cm. Preferably, the resistivity of the high-resistance silicon is greater than 10000Ω·cm. The material of the piezoelectric layer 120 may be lithium tantalate and lithium niobate, wherein the cut angle of the lithium tantalate may be 30° to 50°, and the thickness of the piezoelectric layer 120 may be in the range of 300 to 1000nm. A metal film is deposited on the surface of the piezoelectric layer 120 by electron beam evaporation, plasma, magnetron sputtering, etc. to form the electrode layer 130, wherein the material of the deposited metal film may be titanium, chromium, copper, silver, aluminum, etc., or a combination thereof. The number of first electrode fingers 20, first dummy electrode fingers 30, second electrode fingers 50, and second dummy electrode fingers 60 are all equal, the first electrode fingers 20 and the first dummy electrode fingers 30 are alternately connected on the first sub-bus 11, the first electrode fingers 20 and the first dummy electrode fingers 30 are alternately connected on the second sub-bus 12, the second electrode fingers 50 and the second dummy electrode fingers 60 are alternately connected on the third sub-bus 41, and the second electrode fingers 50 and the second dummy electrode fingers 60 are alternately connected on the fourth sub-bus 42. The first sub-gap 71 is located between the first dummy electrode finger 30 connected to the first sub-bus 11 and the second electrode finger 50 connected to the third sub-bus 41, the third sub-gap 81 is located between the first electrode finger 20 connected to the first sub-bus 11 and the second dummy electrode finger 60 connected to the third sub-bus 41, the second sub-gap 72 is located between the first dummy electrode finger 30 connected to the second sub-bus 12 and the second electrode finger 50 connected to the fourth sub-bus 42, and the fourth sub-gap 82 is located between the first electrode finger 20 connected to the second sub-bus 12 and the second dummy electrode finger 60 connected to the fourth sub-bus 42. The arrangement direction of the first sub-gap 71 is parallel to the arrangement direction of the third sub-gap 81, the first sub-gap 71 is arranged along the first direction x, the angle β between the first direction x and the third direction z is greater than 2° and less than 15°, the arrangement direction of the second sub-gap 72 is parallel to the arrangement direction of the fourth sub-gap 82, the second sub-gap 72 is arranged along the second direction y, and the angle θ between the second direction y and the third direction z is greater than 2° and less than 15°. Figure 3 A schematic diagram of another interdigital transducer provided in an embodiment of the present invention, referring to Figure 3 , the arrangement direction of the first sub-gap 71 and the arrangement direction of the third sub-gap 81 may be parallel to the second direction y, and the arrangement direction of the second sub-gap 72 and the arrangement direction of the fourth sub-gap 82 may be parallel to the first direction x. The number of first electrode fingers 20 connected to the first sub-bus bar 11 and the number of first electrode fingers 20 connected to the second sub-bus bar 12 may be equal or unequal, Figure 4 A schematic diagram of another interdigital transducer provided in an embodiment of the present invention, referring to Figure 4, the number of first electrode fingers 20 connected to the first sub-bus bar 11 is greater than the number of first electrode fingers 20 connected to the second sub-bus bar 12, Figure 5 A schematic diagram of another interdigital transducer provided in an embodiment of the present invention, referring to Figure 5 The number of first electrode fingers 20 connected to the first sub-bus bar 11 is less than the number of first electrode fingers 20 connected to the second sub-bus bar 12. The angle β between the first direction x and the third direction z and the angle θ between the second direction y and the third direction z may be equal or unequal. Figure 6 A schematic diagram of another interdigital transducer provided in an embodiment of the present invention, referring to Figure 6 An included angle β between the first direction x and the third direction z is smaller than an included angle θ between the second direction y and the third direction z. Figure 7 Schematic diagram of the admittance measurement results of the surface acoustic wave resonator in the prior art and the surface acoustic wave resonator provided by the embodiment of the present invention, refer to Figure 7 , Figure 7 The dotted line 21 in FIG. 1 is a schematic diagram showing the relationship between the admittance amplitude and the frequency of the surface acoustic wave resonator in the prior art. Figure 7 The dotted line 22 in FIG. 1 is a schematic diagram showing the relationship between the real part of the admittance of the surface acoustic resonator and the frequency in the prior art. Figure 7 The solid line 23 in FIG. 2 is a schematic diagram showing the relationship between the admittance amplitude and the frequency of the surface acoustic wave resonator provided by the embodiment of the present invention. Figure 7 The solid line 24 in FIG. 2 is a schematic diagram showing the relationship between the real part of the admittance and the frequency of the surface acoustic resonator provided by the embodiment of the present invention. Figure 7 It can be clearly seen that the transverse mode ripples appear in the relationship curve between the real part of the admittance and the frequency of the surface acoustic wave resonator in the prior art, wherein the transverse mode ripples include ripples a1-a6. In practical applications, the generation of more transverse mode ripples is not suitable for the generation of radio frequency filters. Figure 7 The solid line 24 does not appear Figure 7 From the transverse mode ripples a1 - a6 shown by the dotted line 22 , it can be seen that the surface acoustic wave resonator provided by the embodiment of the present invention can effectively suppress the transverse ripples. Figure 8 A schematic diagram of the measured results of the real part of the admittance of the surface acoustic wave resonator provided by the embodiment of the present invention when the angles between the first direction and the third direction are different, Fig. 9 Schematic diagram of the measured results of the admittance amplitude of the surface acoustic wave resonator provided in the embodiment of the present invention when the angles between the first direction and the third direction are different, refer to Figure 8 and Fig. 9, a certain dB value is added to the ordinate to make the diagram of the measured results look more intuitive. When the angle between the first direction and the third direction is 0°, and the angle between the second direction and the third direction is equal to the angle between the first direction and the third direction, the surface acoustic wave resonator has serious transverse mode ripples. When the angle between the first direction and the third direction is 3°, 5°, 7° and 11° respectively, and the angle between the second direction and the third direction is equal to the angle between the first direction and the third direction, the transverse mode ripples can be effectively suppressed. Preferably, the angle between the first direction and the third direction is above 3°, and the suppression effect of the transverse mode ripples is more obvious. It should be noted that when the angle between the first direction and the third direction changes, and the angle between the second direction and the third direction changes, the length, width and direction of the first electrode finger, the second electrode finger, the first dummy electrode finger and the second dummy electrode finger remain unchanged.

[0054] The surface acoustic wave resonator provided by the embodiment of the present invention suppresses the transverse mode ripples of the surface acoustic wave resonator by changing the angle between the first direction and the third direction and the angle between the second direction and the third direction. When the angle between the first direction and the third direction is in the range of 2° to 15° and the angle between the second direction and the third direction is in the range of 2° to 15°, the transverse mode ripples can be effectively suppressed. The surface acoustic wave resonator provided by the embodiment of the present invention can effectively suppress the transverse mode ripples.

[0055] Optional, continue to refer to Figure 2 The first sub-bus bar 11 is parallel to the third sub-bus bar 41 , the length direction of the first sub-bus bar 11 is parallel to the first direction x, the second sub-bus bar 12 is parallel to the fourth sub-bus bar 42 , and the length direction of the second sub-bus bar 12 is parallel to the second direction y.

[0056] Specifically, the arrangement direction of the first sub-gap 71 is parallel to the length direction of the first sub-bus bar 11, the third sub-gap 81 is parallel to the length direction of the third sub-bus bar 41, the arrangement direction of the second sub-gap 72 is parallel to the length direction of the second sub-bus bar 12, and the arrangement direction of the fourth sub-gap 82 is parallel to the length direction of the fourth sub-bus bar 42. It should be noted that the direction of the line connecting the aperture center points of the first electrode fingers 20 connected to the first sub-bus bar 11 is parallel to the first direction x, the direction of the line connecting the aperture center points of the second electrode fingers 50 connected to the third sub-bus bar 41 is parallel to the first direction x, the direction of the line connecting the aperture center points of the first electrode fingers 20 connected to the second sub-bus bar 12 is parallel to the second direction y, and the direction of the line connecting the aperture center points of the second electrode fingers 50 connected to the fourth sub-bus bar 42 is parallel to the second direction y.

[0057] Optional, continue to refer to Figure 2A first electrode finger 20 is disposed between adjacent first gaps 70 , and a second electrode finger 50 is disposed between adjacent second gaps 80 .

[0058] Specifically, the first gap 70 includes a first sub-gap 71 and a second sub-gap 72. A first electrode finger 20 is disposed between the first gap 70. A first electrode finger 20 may be disposed between the first sub-gap 71 and the first sub-gap 71, or between the second sub-gap 72 and the second sub-gap 72, or between the first sub-gap 71 and the second sub-gap 72. The second gap 80 includes a third sub-gap 81 and a fourth sub-gap 82. A second electrode finger 50 is disposed between the second gap 80. A second electrode finger 50 may be disposed between the third sub-gap 81 and the third sub-gap 81, or between the fourth sub-gap 82 and the fourth sub-gap 82, or between the third sub-gap 81 and the fourth sub-gap 82.

[0059] Optional, Fig.10 A schematic diagram of the structure of another interdigital transducer provided in an embodiment of the present invention, referring to Fig.10 The first electrode finger 20 and the second electrode finger 50 both include a main body 11 and a terminal 12 integrally connected to the main body 11, the terminal 12 of the first electrode finger 20 is located on a side of the main body 11 of the first electrode finger 20 away from the first bus bar 10, and the terminal 12 of the second electrode finger 50 is located on a side of the main body 11 of the second electrode finger 50 away from the second bus bar 40; the first dummy electrode finger 30 and the second dummy electrode finger 60 both include a main body 11 and a terminal 12 integrally connected to the main body 11, the terminal 12 of the first dummy electrode finger 30 is located on a side of the main body 11 of the first dummy electrode finger 30 away from the first bus bar 10, and the terminal 12 of the second dummy electrode finger 60 is located on a side of the main body 11 of the second dummy electrode finger 60 away from the second bus bar 40; in the third direction z, the width of the terminal 12 is greater than the width of the main body 11.

[0060] Specifically, the propagation direction of the surface acoustic wave is parallel to the third direction z, and setting the width of the end 12 to be greater than the width of the main body 11 can enable the end 12 to block the lateral energy leakage in the surface acoustic wave, suppress the clutter in the surface acoustic wave, and improve the Q value of the surface acoustic wave resonator. It should be noted that Fig.10 The shape of the end head 12 is shown as a rectangle for exemplary purposes only. The shape of the end head 12 may also be a triangle or a polygon.

[0061] Optionally, in the third direction, the width of the end is 1.2 to 1.8 times the width of the main body.

[0062] Specifically, the width of the end is set to 1.2 to 1.8 times the width of the main body, and the length of the end along the length direction of the first electrode finger is set to 0.3 to 0.7 times the wavelength of the interdigital transducer. This can further enable the end to block lateral energy leakage in the surface acoustic wave, better suppress clutter in the surface acoustic wave, and further improve the Q value of the surface acoustic wave resonator.

[0063] Optional, continue to refer to Fig.10 The terminal 12 on the first electrode finger 20 is arranged opposite to the terminal 12 on the second dummy electrode finger 60 ; the terminal 12 on the second electrode finger 50 is arranged opposite to the terminal 12 on the first dummy electrode finger 30 .

[0064] Specifically, the terminal 12 on the first electrode finger 20 is arranged opposite to the terminal 12 on the second dummy electrode finger 60, and the terminal 12 on the second electrode finger 50 is arranged opposite to the terminal 12 on the first dummy electrode finger 30, so that the terminal 12 can further block the lateral energy leakage in the surface acoustic wave, better suppress the clutter in the surface acoustic wave, and further improve the Q value of the surface acoustic wave resonator.

[0065] Optionally, along the length direction of the first electrode finger, the length of the first dummy electrode finger is 0.5 to 1.5 times the wavelength of the interdigital transducer; and the aperture of the interdigital transducer is 9 to 40 times the wavelength of the interdigital transducer.

[0066] Specifically, setting the length of the first dummy electrode finger to 0.5 to 1.5 times the wavelength of the interdigital transducer and setting the aperture of the interdigital transducer to 9 to 40 times the wavelength of the interdigital transducer can further significantly improve the Q value of the surface acoustic wave resonator.

[0067] Optional, Fig.11 A schematic diagram of a top view structure of an electrode layer provided in an embodiment of the present invention, Fig.12 A schematic diagram of a top view of another electrode layer provided in an embodiment of the present invention, referring to Fig.11 and 12, the electrode layer further includes a reflective grid structure 132; the reflective grid structure 132 includes a third bus bar 90, a fourth bus bar 91 and a reflective grid 92; the third bus bar 90 is arranged in parallel with the fourth bus bar 91; the first end of the reflective grid 92 is connected to the third bus bar 90, and the second end of the reflective grid 92 is connected to the fourth bus bar 91; a reflective grid structure 132 is arranged on the side of the first sub-bus bar 11 away from the second sub-bus bar 12, and a reflective grid structure 132 is arranged on the side of the second sub-bus bar 12 away from the first sub-bus bar 11; wherein, The third bus bar 90 is perpendicular to the reflective grid 92 and the angle between the third bus bar 90 and the first direction x is in the range of 2 to 15°; or the angle between the third bus bar 90 and the reflective grid 92 is in the range of 75° to 88° and the length direction of the third bus bar 90 in the reflective grid structure 132 located on the side of the first sub-bus bar 11 away from the second sub-bus bar 12 is parallel to the first direction x, and the length direction of the third bus bar 90 in the reflective grid structure 132 located on the side of the second sub-bus bar 12 away from the first sub-bus bar 11 is parallel to the second direction y.

[0068] Specifically, Fig.11 The reflective grid 92 in the middle reflective grid structure 132 is perpendicular to the third bus bar 90. Fig.12 The angle between the reflective grid 92 in the reflective grid structure 132 and the third bus bar 90 is in the range of 75° to 88°. Fig.11 , when the angle between the first direction x and the third direction z is β, the angle between the third bus bar 90 and the first direction x is also β. Fig.12 When the angle between the first direction x and the third direction z is β, the third bus bar 90 is parallel to the first direction x, and the angle between the reflective grid 92 and the third bus bar 90 is 90°-β. Fig.13 A schematic diagram of a top view of another electrode layer provided in an embodiment of the present invention, referring to Fig.13 When the angle between the second direction y and the third direction z is θ, the angle between the third bus bar 90 and the second direction y is also θ. Fig.14 A schematic diagram of a top view of another electrode layer provided in an embodiment of the present invention, referring to Fig.14 The length direction of the third bus bar 90 in the reflection grid structure 132 located on the side of the first sub-bus bar 11 away from the second sub-bus bar 12 is parallel to the second direction y, and the length direction of the third bus bar 90 in the reflection grid structure 132 located on the side of the second sub-bus bar 12 away from the first sub-bus bar 11 is parallel to the first direction x. Fig.15 A schematic diagram of a top view of another electrode layer provided in an embodiment of the present invention, referring to Fig.15, the interdigital transducer 131 in the electrode layer provided in the embodiment of the present invention can be a plurality of interdigital transducers 131 connected in series, and the reflection grating structure 132 is located on both sides of the interdigital transducers 131 connected in series. The reflection grating structure 132 can reflect the energy of the surface acoustic wave and concentrate the energy in the interdigital transducer. In the embodiment of the present invention, the reflection grating 92 is always arranged in parallel with the first electrode finger, the second electrode finger, the first dummy electrode finger and the second dummy electrode finger, so as to further ensure that the reflection grating structure 132 concentrates the energy of the reflected surface acoustic wave into the interdigital transducer, and further improve the Q value of the surface acoustic wave resonator. Among them, the number of reflection gratings 92 in each reflection grating structure 132 is 15 to 30. It should be noted that the interdigital transducer in the schematic diagram of the top view structure of the electrode layer provided in the embodiment of the present invention includes an end connected integrally with the main body, and the interdigital transducer in the electrode layer may not include an end connected integrally with the main body. Optionally, Fig.16 A schematic diagram of a top view of a surface acoustic wave resonator provided in an embodiment of the present invention, referring to Fig.16 The piezoelectric material of the piezoelectric layer 120 includes a positioning edge 121, and the positioning edge 121 of the piezoelectric material is parallel to the first electrode finger, the second electrode finger, the first dummy electrode finger, and the second dummy electrode finger.

[0069] Specifically, a positioning edge 121 is set in the piezoelectric material, and the first electrode finger, the second electrode finger, the first dummy electrode finger and the second dummy electrode finger in each interdigital transducer are parallel to the positioning edge 121, so that each interdigital transducer in the electrode layer can be arranged parallel to each other. Since the propagation direction of the surface acoustic wave is perpendicular to the positioning edge 121, each first electrode finger, the second electrode finger, the first dummy electrode finger and the second dummy electrode finger in the interdigital transducer can block the lateral energy leakage in the surface acoustic wave, better suppress the clutter in the surface acoustic wave, and further improve the Q value of the surface acoustic wave resonator.

[0070] Optional, continue to refer to Figure 1 The surface acoustic wave resonator provided by the embodiment of the present invention also includes an energy trap layer 140, which is located between the substrate 110 and the piezoelectric layer 120; a first dielectric layer 150, which is located between the energy trap layer 140 and the piezoelectric layer 120; and a second dielectric layer 160, which is located on a side of the electrode layer 130 away from the piezoelectric layer 120 and covers the electrode layer 130.

[0071] Specifically, an energy trap layer 140 is prepared on the substrate 110. The material of the energy trap layer 140 can be polysilicon. The setting of the energy trap layer 140 can reduce the accumulation of charges and further improve the Q value of the surface acoustic wave resonator. A layer of low-sound-velocity silicon dioxide is grown on the side of the energy trap layer 140 away from the substrate 110 by plasma-enhanced chemical vapor deposition or thermal oxidation of silicon to form a first dielectric layer 150. Chemical mechanical planarization is used to finally control the thickness of the first dielectric layer 150 within the range of 300 to 800 nm. The first dielectric layer 150 can further improve the temperature drift coefficient. The second dielectric layer 160 serves as a passivation layer and a frequency modulation layer of the surface acoustic wave resonator. The material of the second dielectric layer 160 can be silicon dioxide or silicon nitride. The second dielectric layer 160 covers the electrode layer 130. The substrate 110, the energy trap layer 140 and the first dielectric layer 150 constitute a composite multilayer substrate. The composite multilayer substrate in the embodiment of the present invention can enable the surface acoustic wave resonator and the radio frequency filter to achieve low insertion loss, passband smoothness, high Q value and excellent low frequency temperature and other characteristics.

[0072] An embodiment of the present invention provides a radio frequency filter, which includes the surface acoustic wave resonator provided by any embodiment of the present invention.

[0073] Specifically, Fig.17 Schematic diagram of the measured insertion loss of the radio frequency filter in the prior art and the radio frequency filter provided by the embodiment of the present invention, refer to Fig.17 , Fig.17 The dotted line in FIG. 1 is a schematic diagram showing the relationship between the insertion loss and the frequency of the radio frequency filter in the prior art. Fig.17 The solid line in FIG. 1 is a schematic diagram showing the relationship between the insertion loss and the frequency of the radio frequency filter provided by the embodiment of the present invention. Fig.17 It can be seen that the insertion loss of the RF filter in the prior art is unstable and the passband noise is serious. The serious passband noise will lead to the deterioration of the overall device performance. However, there is no noise in the passband of the RF filter provided in the embodiment of the present invention. It can be seen that the RF filter provided in the embodiment of the present invention can make the passband smoother.

[0074] The radio frequency filter provided in the embodiment of the present invention has corresponding beneficial effects as the surface acoustic wave resonator provided in any embodiment of the present invention. The technical details not detailed in this embodiment are detailed in the surface acoustic wave resonator provided in any embodiment of the present invention.

[0075] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the embodiments of the present invention are not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the protection scope of the embodiments of the present invention. Therefore, although the embodiments of the present invention are described in more detail through the above embodiments, the embodiments of the present invention are not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the embodiments of the present invention, and the scope of the embodiments of the present invention is determined by the scope of the appended claims.

Claims

1. A surface acoustic wave resonator, characterized in that: include: Substrate; wherein the material of the substrate includes high-resistance silicon; a piezoelectric layer located on the substrate; an electrode layer, the electrode layer being located on a side of the piezoelectric layer away from the substrate; The electrode layer includes an interdigital transducer, and the interdigital transducer includes: a first bus bar and first electrode fingers and first dummy electrode fingers alternately connected to the first bus bar; a second bus bar and second electrode fingers and second dummy electrode fingers alternately connected to the second bus bar; the first electrode finger and the second dummy electrode finger are arranged opposite to each other, and a first gap is formed between the first electrode finger and the second dummy electrode, and the second electrode finger and the first dummy electrode are arranged opposite to each other, and a second gap is formed between the second electrode finger and the first dummy electrode; The first bus bar includes a first sub-bus bar and a second sub-bus bar, and the first sub-bus bar and the second sub-bus bar are connected; The second bus bar includes a third sub-bus bar and a fourth sub-bus bar, and the third sub-bus bar is connected to the fourth sub-bus bar; the first gap includes a first sub-gap and a second sub-gap, and the second gap includes a third sub-gap and a fourth sub-gap, the first sub-gap and the third sub-gap are located between the first sub-bus bar and the third sub-bus bar, and the second sub-gap and the fourth sub-gap are located between the second sub-bus bar and the fourth sub-bus bar; Wherein, each of the first sub-gaps is arranged along the first direction, each of the third sub-gaps is arranged along the first direction, each of the second sub-gaps is arranged along the second direction, and each of the fourth sub-gaps is arranged along the second direction; The angle between the first direction and the third direction is in the range of 2° to 15°, the angle between the second direction and the third direction is in the range of 2° to 15°, and in the direction parallel to the plane of the piezoelectric layer, the third direction is perpendicular to the length direction of the first electrode finger.

2. The surface acoustic wave resonator according to claim 1, characterized in that: The first sub-bus bar is parallel to the third sub-bus bar, and the length direction of the first sub-bus bar is parallel to the first direction. The second sub-bus bar is parallel to the fourth sub-bus bar, and the length direction of the second sub-bus bar is parallel to the second direction.

3. The surface acoustic wave resonator according to claim 1, characterized in that: A first electrode finger is disposed between adjacent first gaps, and a second electrode finger is disposed between adjacent second gaps.

4. The surface acoustic wave resonator according to claim 1, characterized in that: The first electrode finger and the second electrode finger each include a main body and a terminal integrally connected to the main body, the terminal of the first electrode finger is located on a side of the main body of the first electrode finger away from the first bus bar, and the terminal of the second electrode finger is located on a side of the main body of the second electrode finger away from the second bus bar; The first dummy electrode finger and the second dummy electrode finger each include a main body and a terminal integrally connected to the main body, the terminal of the first dummy electrode finger is located on a side of the main body of the first dummy electrode finger away from the first bus bar, and the terminal of the second dummy electrode finger is located on a side of the main body of the second dummy electrode finger away from the second bus bar; In the third direction, the width of the end head is greater than the width of the main body.

5. The surface acoustic wave resonator according to claim 2, characterized in that: In the third direction, the width of the end is 1.2 to 1.8 times the width of the main body.

6. The resonator according to claim 2, characterized in that The end of the first electrode finger is arranged opposite to the end of the second dummy electrode finger; The end of the second electrode finger is arranged opposite to the end of the first dummy electrode finger.

7. The surface acoustic wave resonator according to claim 1, characterized in that: The electrode layer also includes a reflective grid structure; The reflective grid structure includes a third bus bar, a fourth bus bar and a reflective grid; the third bus bar is arranged in parallel with the fourth bus bar; The first end of the reflective grid is connected to the third bus bar, and the second end of the reflective grid is connected to the fourth bus bar; A reflective grating structure is provided on a side of the first sub-bus bar away from the second sub-bus bar, and a reflective grating structure is provided on a side of the second sub-bus bar away from the first sub-bus bar; Wherein, the third bus bar is perpendicular to the reflector and the angle between the third bus bar and the first direction is in the range of 2 to 15°; Or the angle between the third bus bar and the reflective grid is in the range of 75° to 88° and the length direction of the third bus bar in the reflective grid structure located on the side of the first sub-bus bar away from the second sub-bus bar is parallel to the first direction, and the length direction of the third bus bar in the reflective grid structure located on the side of the second sub-bus bar away from the first sub-bus bar is parallel to the second direction.

8. The surface acoustic wave resonator according to claim 1, characterized in that: The piezoelectric material of the piezoelectric layer includes a positioning edge, and the positioning edge of the piezoelectric material is parallel to the first electrode finger, the second electrode finger, the first dummy electrode finger, and the second dummy electrode finger.

9. The surface acoustic wave resonator according to claim 1, characterized in that: Also included is an energy trap layer, the energy trap layer being located between the substrate and the piezoelectric layer; A first dielectric layer, wherein the first dielectric layer is located between the energy trap layer and the piezoelectric layer; A second dielectric layer is located on a side of the electrode layer away from the piezoelectric layer and covers the electrode layer.

10. A radio frequency filter, characterized in that: The surface acoustic wave resonator comprises the surface acoustic wave resonator according to any one of claims 1 to 9.

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