Resonator, filter and radio frequency front-end module

Abstract

The invention discloses a resonator, a filter and a radio frequency front end module, the resonator comprises a piezoelectric substrate, an interdigital transducer and a first dielectric layer, and the interdigital transducer is arranged on the piezoelectric substrate; the first dielectric layer at least covers a partial region of the interdigital transducer; the interdigital transducer comprises two bus bars and a plurality of electrode fingers connected to the two bus bars respectively, an active area and gap areas located at the two ends of the active area in the first direction are formed between the two bus bars, and the first direction intersects with the second direction; the first dielectric layer is provided with a strip-shaped groove, the groove is filled with a high-sound-velocity material to form a dielectric strip, the extension direction of the dielectric strip intersects with the second direction, the dielectric strip and the electrode fingers are arranged in a staggered mode in the second direction, the active area at least comprises a central area, and the projection of the dielectric strip in the second direction at least covers the projection of the central area in the second direction. And the dispersion curve is adjusted to be smoother, so that the suppression of the transverse mode is realized.

Description

Technical Field

[0001] The present application relates to the field of radio frequency filtering technology, and in particular to a resonator, a filter and a radio frequency front-end module. Background Art

[0002] SAW (Surface Acoustic Wave) resonator is the abbreviation of surface acoustic wave resonator. It is a special filtering device made by using its piezoelectric effect and the physical characteristics of surface acoustic wave propagation. It is widely used in various fields, such as the radio frequency field. Among them, the surface acoustic wave is an elastic wave with energy concentrated near the surface. During the operation of the surface acoustic wave resonator, in addition to generating the required main mode, it also generates transverse modes. The existence of transverse modes will cause the performance of the surface acoustic wave resonator to deteriorate.

[0003] Therefore, how to suppress the transverse mode becomes an urgent problem to be solved. Summary of the invention

[0004] In view of this, the present application proposes a resonator, a filter and a radio frequency front-end module.

[0005] A first aspect of the present application provides a resonator, comprising:

[0006] A piezoelectric substrate having a first surface;

[0007] an interdigital transducer, the interdigital transducer being disposed on the first surface of the piezoelectric substrate; and

[0008] a first dielectric layer, wherein the first dielectric layer covers at least a partial area of ​​the interdigital transducer;

[0009] The interdigital transducer comprises:

[0010] two bus bars disposed on the piezoelectric substrate opposite to each other along a first direction; and

[0011] A plurality of electrode fingers respectively connected to the two bus bars, wherein the electrode fingers connected to the two bus bars are arranged alternately and spaced in sequence in the second direction, and a gap is provided between the electrode fingers connected to each bus bar and another bus bar, so as to form an active area between the two bus bars and a gap area located at both ends of the active area in the first direction, wherein the active area is an area where projections of the electrode fingers along the second direction overlap, the first direction intersects with the second direction, and the second direction is a propagation direction of the sound wave;

[0012] Among them, the first dielectric layer is provided with a strip groove, the groove is filled with a high acoustic velocity material to form a dielectric strip, the extension direction of the dielectric strip intersects with the second direction, the dielectric strip and the electrode finger are staggered in the second direction, the active area at least includes a central area, and the projection of the dielectric strip along the second direction at least covers the projection of the central area along the second direction.

[0013] A second aspect of the present application provides a filter, comprising the above-mentioned resonator.

[0014] A third aspect of the present application provides a radio frequency front-end module, comprising the above-mentioned filter.

[0015] The resonator proposed in the present application fills a high-sound-velocity material in the groove to adjust the acoustic field relationship between the aperture direction and the propagation direction of the sound wave, so as to adjust the dispersion curve to make the dispersion curve smooth, so that the slope of the dispersion curve near the wave number equal to 0 in the aperture direction is closer to 0, that is, the dispersion curve is flatter and less concave and convex, thereby achieving the suppression of the transverse mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained like these drawings without paying any creative work.

[0017] Figure 1a is a schematic diagram of a structure of a resonator from a top view according to an embodiment of the present application;

[0018] Figure 1b is another schematic diagram of the structure of the resonator proposed in the embodiment of the present application from a top view angle;

[0019] Figure 1c is another schematic diagram of the structure of the resonator proposed in the embodiment of the present application from a top view angle;

[0020] Figure 2 is a schematic diagram of the structure from a top view of the deformation mode of the resonator proposed in the embodiment of the present application;

[0021] Figure 3 is a cross-sectional schematic diagram of a resonator proposed in an embodiment of the present application;

[0022] Figure 4 yes Figure 3 A schematic diagram of a local structure in the resonator shown;

[0023] Figure 5 is a cross-sectional schematic diagram of a deformation mode of a resonator proposed in an embodiment of the present application;

[0024] Figure 6 yes Figure 5 A schematic diagram of a local structure in the resonator shown;

[0025] Figure 7 is a cross-sectional schematic diagram of another deformation mode of the resonator proposed in the embodiment of the present application;

[0026] Figure 8 is a cross-sectional schematic diagram of another deformation mode of the resonator proposed in the embodiment of the present application;

[0027] Fig. 9 is a comparison diagram of the dispersion curve of the existing resonator and the dispersion curve of the resonator of the embodiment of the present application;

[0028] Fig.10 It is a comparison diagram of the real part of admittance and the admittance amplitude curve of the existing resonator and the real part of admittance and the admittance amplitude curve of the embodiment of the present application.

[0029] Description of reference numerals:

[0030] 100, resonator; 10, piezoelectric substrate; 10a, first surface; 20, interdigital transducer; 21, bus bar; 22, electrode finger; 23, piston structure; 30, first dielectric layer; 31, first sublayer; 32, second sublayer; 40, groove; 40a, dielectric strip; 41, first side; 42, second side; 43, third side; 50, second dielectric layer; 60, third dielectric layer; A1, active area; A11, central area; A12, edge area; B1, gap area. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0032] It should be understood that all directional indications in the embodiments of the present application (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0033] It should also be understood that when an element is referred to as being "fixed" or "disposed on" another element, it can be directly on the other element or there may be an intermediate element at the same time. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or it can be indirectly connected to the other element through an intermediate element.

[0034] The terms used in this specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. For example, the descriptions of "first", "second", etc. in the present application are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0035] It should be further understood that the term “and / or” used in the specification and appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0036] SAW (Surface Acoustic Wave) resonator is the abbreviation of surface acoustic wave resonator. It is a special filtering device made by using its piezoelectric effect and the physical characteristics of surface acoustic wave propagation. It is widely used in various fields, such as the radio frequency field. Among them, the surface acoustic wave is an elastic wave with energy concentrated near the surface.

[0037] The SAW resonator generally includes a piezoelectric substrate and an interdigital transducer (IDT) disposed on the piezoelectric substrate. When a voltage signal is applied to the piezoelectric substrate, the interdigital transducer 20 excites an acoustic wave in the piezoelectric material. Specifically, the interdigital transducer includes two bus bars and a plurality of electrode fingers respectively connected to the two bus bars and alternately arranged along the propagation direction of the acoustic wave. The overlapping length of the projections of the plurality of electrode fingers along the propagation direction of the acoustic wave is called the aperture of the IDT, and the extension direction of the electrode fingers is called the aperture direction.

[0038] In the process of operation, the surface acoustic wave resonator will generate transverse modes in addition to the main mode it needs. The principle of the generation of transverse modes is as follows: the sound wave in the IDT (Inter Digital Transducer) propagates along the propagation direction, but due to the limited aperture, there will be a component in the aperture direction during the propagation process. At this time, there will be sound wave energy in the aperture direction and resonate in the central area of ​​the IDT, forming the main mode of the transverse mode; the structure of the edge area of ​​the IDT is not completely symmetrical, so some high-order spurious modes may also be formed. The existence of transverse modes and spurious modes will cause the performance of the surface acoustic wave resonator to deteriorate.

[0039] Therefore, an embodiment of the present application proposes a resonator that can suppress the transverse mode.

[0040] See also Figures 1a to 3 The embodiment of the present application proposes a resonator 100, including a piezoelectric substrate 10, an IDT 20 and a first dielectric layer 30, wherein the piezoelectric substrate 10 has a first surface 10a; the IDT 20 is arranged on the first surface 10a of the piezoelectric substrate 10; the first dielectric layer 30 covers at least a partial area of ​​the IDT 20; it can be understood that the first dielectric layer 30 covers at least a partial area of ​​the IDT 20, and may completely cover the IDT 20, or may not completely cover the IDT 20, for example, only completely covers the area where the electrode fingers 22 of the IDT 20 are located, while the area where the bus bar 21 is located is not covered or partially covered.

[0041] The interdigital transducer 20 includes two bus bars 21 arranged on the piezoelectric substrate 10 relatively along a first direction and a plurality of electrode fingers 22 respectively connected to the two bus bars 21. The electrode fingers 22 connected to the two bus bars 21 are arranged alternately and spaced in sequence in the second direction, and there is a gap between the electrode finger 22 connected to each bus bar 21 and another bus bar 21, so as to form an active area A1 between the two bus bars 21 and a gap area B1 located at both ends of the active area A1 in the first direction. The active area A1 is an area where the projections of the electrode fingers 22 along the second direction overlap, the first direction intersects with the second direction, and the second direction is the propagation direction of the sound wave.

[0042] Among them, the first dielectric layer 30 is provided with a strip groove 40, and the groove 40 is filled with a high acoustic velocity material to form a dielectric strip 40a. The extension direction of the dielectric strip 40a intersects with the second direction. The dielectric strip 40a and the electrode finger 22 are staggered in the second direction. The active area A1 at least includes a central area A11, and the projection of the dielectric strip 40a along the second direction at least covers the projection of the central area A11 along the second direction.

[0043] The central area A11 is the core area of ​​the active area A1. In the central area A11, sound waves can propagate at a stable sound speed. The active area A1 may be partially the central area A11 or the entire area may be the central area A11.

[0044] As an implementation method, Figure 1a , Figure 1b , Figure 1c As shown, at the two edges of the active area A1 along the first direction, each electrode finger can be widened or thickened. Correspondingly, the area where the electrode finger is widened or thickened is called the edge area, and the area between the two edge areas is called the central area. In the central area, the width and metal thickness of the same electrode finger remain almost unchanged.

[0045] As an implementation method, Figure 2 As shown, in the entire active area A1, the width and metal thickness of the same electrode finger remain almost unchanged, so the entire active area A1 is the central area.

[0046] In the embodiment of the present application, the first dielectric layer 30 may be made of a temperature compensation material, so that the first dielectric layer 30 is a temperature compensation layer for adjusting the frequency temperature coefficient of the resonator 100 , improving the frequency-temperature characteristic, and thus enhancing the performance of the resonator 100 .

[0047] It can be understood that the dielectric strip 40 a and the electrode finger 22 are staggered in the second direction, which means that there is a gap between the dielectric strip 40 a and the electrode finger 22 but there is no direct contact.

[0048] The resonator 100 proposed in the embodiment of the present application opens a groove 40 in the first dielectric layer 30, and fills the groove 40 with a high sound velocity material to form a dielectric strip 40a whose extension direction intersects with the second direction, so that the projection of the dielectric strip 40a along the second direction at least covers the projection of the central area A11 along the second direction, thereby adjusting the acoustic field relationship between the aperture direction and the propagation direction of the sound wave, so as to adjust the dispersion curve so that the dispersion curve becomes smooth, so that the slope of the dispersion curve near the wave number equal to 0 in the aperture direction is closer to 0, that is, the dispersion curve is flatter and has a smaller unevenness, thereby achieving the suppression of the transverse mode.

[0049] It should be noted that the dispersion curve reflects the relationship between the acoustic wave number along the acoustic wave propagation direction and the acoustic wave number propagating laterally along the aperture direction. Generally speaking, when the transverse wave number is close to 0, the smaller the absolute value of the slope of the dispersion curve, the smaller the transverse mode. The present application can improve the dispersion curve by setting the groove 40 and the dielectric strip 40a, so that the frequency of the low-order transverse mode is as close as possible to the main mode, thereby making the transverse mode as small as possible to achieve the suppression of the transverse mode.

[0050] See also Fig. 9 , Fig. 9 1 is a comparison diagram of the dispersion curve of the existing resonator (ordinary structure) and the dispersion curve of the resonator 100 of the embodiment of the present application. The solid line in the figure is the dispersion curve of the embodiment of the present application, and the dotted line is the dispersion curve of the prior art (ordinary structure). The ordinary structure refers to an ordinary resonator without strip grooves and dielectric strips in the first dielectric layer. Fig. 9 It can be seen that the slope of the embodiment of the present application near the wave number equal to 0 in the aperture direction is smaller than the slope of the ordinary structure near the wave number equal to 0 in the aperture direction, that is, the dispersion curve of the resonator 100 of the embodiment of the present application is flatter than that of the prior art (ordinary structure).

[0051] See also Fig.10 , Fig.10 is a comparison diagram of the real part of admittance and the amplitude of admittance of the existing resonator (ordinary structure) and the real part of admittance and the amplitude of admittance of the structure of the embodiment of the present application, Fig.10 It can be seen that in the frequency band of 2.7 GHz-2.8 GHz, the peak of the admittance (Y11) curve of the resonator 100 according to the embodiment of the present application is smaller, and the transverse mode intensity is significantly smaller than the transverse mode intensity of the existing resonator (ordinary structure).

[0052] Therefore, the resonator 100 according to the embodiment of the present application can adjust the dispersion curve and the admittance curve by disposing the groove 40 and the dielectric strip 40 a, so that the dispersion curve and the admittance curve are flatter, thereby achieving the suppression of the transverse mode.

[0053] The resonator 100 of the present application is a surface acoustic wave (SAW) resonator 100, and the resonator 100 further includes two reflectors, which are arranged on both sides of the IDT 20 along the propagation direction of the acoustic wave. The reflectors are used to confine the surface acoustic wave within the IDT 20.

[0054] The piezoelectric substrate 10 may be made of piezoelectric materials such as lithium niobate, lithium tantalate or quartz, so as to have a piezoelectric effect, that is, charge distribution and mechanical deformation will be generated when an electric field or mechanical stress is applied.

[0055] As an important component of the resonator 100, the IDT 20 is used to complete the conversion of electrical energy and mechanical energy, that is, to generate and detect surface acoustic waves. The structure of the IDT 20 is usually manufactured on the piezoelectric layer using a photolithography-coating-stripping or coating-photolithography-etching process, and can also be manufactured by other process methods.

[0056] When a voltage signal is applied to the piezoelectric substrate 10, the interdigital transducer 20 excites acoustic waves in the piezoelectric material. The changing voltage causes the piezoelectric substrate 10 to deform, thereby exciting surface acoustic waves, which are generated and propagated on the surface of the piezoelectric substrate 10 using the piezoelectric effect, thereby realizing signal processing and transmission.

[0057] Specifically, the electrode fingers 22 of the IDT 20 are used to excite and detect surface acoustic waves on the surface of the piezoelectric substrate 10 to achieve mutual conversion between electrical signals and acoustic signals. The bus bar 21 of the IDT 20 is used to connect the electrode fingers 22 and transmit electrical signals. For example, when a plurality of IDTs 20 are provided in the resonator 100, different IDTs 20 can be electrically connected through the bus bar 21 and the wiring.

[0058] In an optional embodiment, the piezoelectric substrate 10 may be a single-layer piezoelectric structure, that is, the piezoelectric substrate 10 is composed of one piezoelectric material. Of course, in other embodiments, the piezoelectric substrate 10 may also be a multi-layer piezoelectric structure, composed of piezoelectric layers of different materials or the same material but with different properties, and these layers are stacked together in a specific manner to achieve the desired performance.

[0059] In some embodiments, the multilayer piezoelectric structure includes a piezoelectric film and a substrate, the interdigital transducer 20 is arranged on the piezoelectric film, and the substrate is arranged on the side of the piezoelectric film facing away from the interdigital transducer 20. The piezoelectric film is the core part of the piezoelectric substrate 10, and is made of piezoelectric material, such as a piezoelectric material with lithium niobate, lithium tantalate or quartz as the main component. The piezoelectric film has a good piezoelectric effect and can convert mechanical stress into electrical signals or convert electrical signals into mechanical stress. The substrate is the supporting layer of the piezoelectric film, and its main function is to provide mechanical support and protect the piezoelectric film, while ensuring that the piezoelectric film can be uniformly stressed when subjected to external force. In addition, the substrate can also form a specific acoustic structure together with the piezoelectric film to optimize the performance of the resonator 100.

[0060] In some embodiments, the piezoelectric film can be made of lithium niobate with a YX cut of 0°-50°, 110°-180°. Using the above-cut lithium niobate as the piezoelectric film can improve the kt of the resonator 100. 2 (electrical coupling coefficient), thereby improving bandwidth.

[0061] In some embodiments, the substrate may be an insulating substrate such as silicon material with high resistivity, sapphire, or spinel.

[0062] In some embodiments, the multilayer piezoelectric structure may further include a temperature compensation layer, which is disposed between the piezoelectric film and the substrate. The temperature compensation layer is used to compensate for the effect of temperature changes on the performance of the piezoelectric substrate 10 through its specific thermal expansion coefficient and mechanical properties. This helps to maintain the stability and reliability of the device under different temperature conditions.

[0063] It can be understood that the material or structure of the piezoelectric substrate 10 of the present application is not limited here, as long as it can achieve the required performance.

[0064] See also Figure 1a , Figure 1b , Figure 1cIn some embodiments, the active area A1 further includes edge areas A12 located at both ends of the central area A11 in the first direction, and the projection of the dielectric strip 40a in the second direction may also at least partially cover the projection of the edge area A12 along the second direction. It can be understood that the acoustic wave mainly propagates in the active area A1. When the portion of the electrode finger 22 in the active area A1 has a widening and / or thickening structure at both ends in the first direction, the area corresponding to the widening and / or thickening structure is the edge area A12, and the area corresponding to the middle portion of the electrode finger 22 without the widening and / or thickening structure is the central area A11.

[0065] For example, the projection of the dielectric strip 40a in the second direction may be as follows: Figure 1b As shown, only the projection of the central area A11 in the second direction is covered, and there is no overlap with the projection of the edge area A12 in the second direction; it can also be as shown in Figure 1a As shown, the projection of the central area A11 in the second direction is completely covered, and the projection of the edge area A12 in the second direction is also completely covered; it can also be as follows Figure 1c The illustrated portion completely covers the projection of the central area A11 in the second direction, and partially covers the projection of the edge area A12 in the second direction.

[0066] In some embodiments, the interdigital transducer 20 further includes a piston structure 23 (the electrode finger 22 is widened and / or thickened), and the piston structure 23 is disposed at the end of the electrode finger 22 located in the edge area A12. Thus, the mass load of the electrode finger 22 on the opposite sides in the first direction can be increased by the provision of the piston structure 23, so as to enhance the suppression of the transverse mode by the resonator 100. Specifically, the mass load of the corresponding area can be increased by the piston structure 23, and the sound velocity on the opposite sides of the active area A1 in the first direction is reduced, so that the edge area A12 forms a low sound velocity area with a lower sound velocity than the middle area, thereby forming a piston mode to change the reflection coefficient of the sound wave, play the role of a phase shifter, and help to further suppress the noise mode.

[0067] In some embodiments, the piston structure 23 is mainly composed of chromium, copper, titanium, silver, molybdenum or gold. Exemplarily, the material of the piston structure 23 can be a combination of one or more metal materials such as chromium, copper, titanium, silver, molybdenum or gold. It can be understood that the piston structure 23 of the present application can also be made of other metal materials, which are not limited here, as long as they can achieve the required performance.

[0068] In some embodiments, the busbar 21 is mainly composed of aluminum, molybdenum, copper, gold, platinum, silver, nickel, chromium or tungsten. Exemplarily, the material of the busbar 21 can be a combination of one or more metal materials such as aluminum, molybdenum, copper, gold, platinum, silver, nickel, chromium or tungsten. It can be understood that the busbar 21 of the present application can also be made of other metal materials, which can be a single metal, an alloy, or a structure formed by stacking multiple metals. It is not limited here, as long as it can achieve the required performance.

[0069] In some embodiments, the electrode fingers 22 and the bus bar 21 may be made of the same or different metal materials. Exemplarily, the material of the electrode fingers 22 may be a combination of one or more metal materials such as aluminum, molybdenum, copper, gold, platinum, silver, nickel, chromium or tungsten. It is understandable that the electrode fingers 22 of the present application may also be made of other metal materials, which may be a single metal, an alloy, or a structure formed by stacking multiple metals. This is not limited here, as long as the required performance can be achieved.

[0070] In some embodiments, the thickness of at least a portion of the electrode finger 22 is the same as the thickness of the bus bar 21. Exemplarily, the main body of the electrode finger 22 can be integrally formed with the bus bar 21, that is, formed in the same process.

[0071] In some embodiments, the metallization rate of the electrode finger 22 is 0.3-0.6, thereby improving the performance of the resonator 100, wherein the metallization rate is the ratio of the width of a single electrode finger 22 to half the electrode finger period. One electrode finger period is the distance between the center lines of two adjacent electrode fingers connected to the same bus bar, and half the electrode finger period is the distance between the center lines of two adjacent electrode fingers 22 connected to two bus bars respectively.

[0072] In some embodiments, the sound speed of the central area A11 is V1, the sound speed of the edge area A12 is V2, and the sound speed of the gap area B1 is V3; wherein, V3>V1>V2, forming a piston mode. The above setting can effectively suppress transverse mode fluctuations and thus effectively close elastic waves.

[0073] Of course, in other embodiments, the active area A1 may not be divided into two areas, such as Figure 2 As shown, the entire active area A1 is regarded as the same area, that is, there is only one central area A11 , and in this case, the ends of the electrode fingers 22 may not be provided with a widening structure and / or a thickening structure.

[0074] In some embodiments, the projection of the dielectric strip 40a along the second direction covers the projection of the active area A1 along the second direction. Exemplarily, the projection of the dielectric strip 40a along the second direction can completely cover the projection of the active area A1 along the second direction and extend to a portion of the projection of the gap area B1 along the second direction, or can completely cover both the projection of the active area A1 along the second direction and the projection of the gap area B1 along the second direction. Of course, when the first dielectric layer 30 also covers the bus bar 21, the projection of the dielectric strip 40a on the interdigital transducer 20 can also extend to connect with the bus bar 21, or extend to the area where the bus bar 21 is located, so as to facilitate the formation of the groove 40 and the filling of the dielectric strip 40a.

[0075] In some embodiments, the projection of the dielectric strip 40 a on the IDT 20 extends from one bus bar 21 to another bus bar 21 to facilitate the processing of the groove 40 and reduce the processing cost.

[0076] In some embodiments, the dielectric strip 40a and the electrode finger 22 both extend along the first direction. Thus, the dielectric strip 40a and the electrode finger 22 are arranged in parallel, so that the dielectric strip 40a and the electrode finger 22 are arranged in a staggered manner, and the distance between the projection of the dielectric strip 40a and the same electrode finger 22 is kept uniform. Of course, in other embodiments, the dielectric strip 40a can also be inclined by 1°-3° relative to the electrode finger 22, and there is no contact between the dielectric strip 40a and the electrode finger 22.

[0077] In some embodiments, the first direction is perpendicular to the second direction. The first direction is the extension direction of the electrode fingers 22, and the second direction is the propagation direction of the sound wave, which is also the extension direction of the bus bar 21. The above layout helps to enhance the mechanical stability and electrical stability of the interdigital transducer 20 and improve the performance of the resonator 100.

[0078] See also Figures 3 to 6 In some embodiments, the groove 40 penetrates the first dielectric layer 30 along the third direction so that the dielectric strip 40a contacts the first surface 10a. The third direction is the thickness direction of the piezoelectric substrate 10, that is, the first direction, the second direction and the third direction are perpendicular to each other. Thus, the groove 40 penetrates the entire first dielectric layer 30, and the high acoustic velocity material is filled to adjust the dispersion curve, which is more convenient for processing. The groove 40 can be formed on the first dielectric layer 30 by etching, etc., which is simple to operate and reduces processing costs.

[0079] In some embodiments, the dielectric strip 40a has a first side surface 41 and a second side surface 42 that are arranged opposite to each other in the third direction, and the second side surface 42 faces the first surface 10a; wherein, in the second direction, the width of the first side surface 41 is greater than or equal to the width of the second side surface 42. When the width of the first side surface 41 is greater than the width of the second side surface 42, the dielectric strip 40a has an inverted trapezoidal structure (e.g., Figure 5 and Figure 6 When the width of the first side 41 is equal to the width of the second side 42, the dielectric strip 40a is a rectangular structure (such as Figure 3 and Figure 4 As shown), the formed resonator 100 has better performance.

[0080] In some embodiments, when the groove 40 runs through the entire first dielectric layer 30, in the second direction, the width of the first side surface 41 is 0.025λ-0.1λ, where λ is the wavelength of the sound wave. By limiting the width of the first side surface 41 of the dielectric strip 40a to the above range, the dispersion curve can be adjusted to make the dispersion curve flatter, thereby suppressing the transverse mode while avoiding affecting the performance of the resonator 100. Exemplarily, the width of the first side surface 41 can be 0.025λ, 0.03λ, 0.035λ, 0.04λ, 0.045λ, 0.05λ, 0.055λ, 0.06λ, 0.065λ, 0.07λ, 0.075λ, 0.08λ, 0.085λ, 0.09λ, 0.095λ or 0.1λ, etc.

[0081] In some embodiments, the width of the first side surface 41 can be further limited to 0.045λ-0.06λ, so as to better adjust the dispersion curve and make the dispersion curve flatter, thereby better suppressing the transverse mode. Exemplarily, the width of the first side surface 41 can be 0.045λ, 0.05λ, 0.055λ, 0.06λ, etc.

[0082] In some embodiments, the dielectric strip 40a has a first side surface 41 and a second side surface 42 that are arranged opposite to each other in a third direction, and a third side surface 43 that is connected to the first side surface 41 and the second side surface 42, the second side surface 42 faces the first surface 10a, and the third direction is the thickness direction of the piezoelectric substrate 10; wherein the first side surface 41 and the second side surface 42 both extend along the second direction, and the angle between the third side surface 43 and the first side surface 41 is 70°-90°. Specifically, when the angle between the third side surface 43 and the first side surface 41 is equal to 90°, in the cross section of the resonator 100 in the side view direction, the dielectric strip 40a has a rectangular structure (such as Figure 3 and Figure 4As shown), the performance of the formed resonator 100 is better. When the angle between the third side surface 43 and the first side surface 41 is less than 90°, the dielectric strip 40a has a trapezoidal structure (as shown in FIG. Figure 5 and Figure 6 It is easier to realize in processing.

[0083] Exemplarily, the angle between the third side surface 43 and the first side surface 41 may be 70°, 75°, 80°, 85°, 90°, etc.

[0084] In some embodiments, in the third direction, the thickness of the first dielectric layer 30 is greater than the thickness of the electrode fingers 22. Thus, the region where the electrode fingers 22 are located can be covered, and the first dielectric layer 30 has a sufficient thickness to realize the function of the first dielectric layer 30. For example, when the first dielectric layer 30 is made of temperature compensation material, a suitable thickness can improve the temperature frequency characteristics.

[0085] In some embodiments, when the groove 40 penetrates the first dielectric layer 30, the thickness of the first dielectric layer 30 in the third direction is 0.15λ-0.45λ. When the thickness of the first dielectric layer 30 is less than 0.15λ, the Q value (Quality Factor) of the resonator 100 is small, and the TCF (Temperature Coefficient of Frequency) is small, and the frequency-temperature characteristic is more obvious. If the thickness of the first dielectric layer 30 is greater than 0.45λ, kt 2 (electric coupling coefficient) is very small and the bandwidth is small. Therefore, the thickness of the first dielectric layer 30 is limited to the range of 0.15λ-0.45λ in the embodiment of the present application, which can balance the Q value and kt of the resonator 100. 2 , compensating the temperature coefficient of the resonator 100 to a suitable size.

[0086] By way of example, the thickness of the first dielectric layer 30 may be 0.15λ, 0.2λ, 0.25λ, 0.3λ, 0.35λ, 0.4λ, 0.45λ, or the like.

[0087] It should be noted that the groove 40 is not limited to being disposed throughout the entire first dielectric layer 30. For example, in other embodiments, the first dielectric layer 30 may be divided into multiple sub-layers, and the multiple sub-layers may be separated by other dielectric layers, so that the groove 40 is disposed in one of the sub-layers.

[0088] See also Figures 7 and 8In some embodiments, the resonator 100 further includes a second dielectric layer 50, the first dielectric layer 30 includes a first sublayer 31 and a second sublayer 32, the first sublayer 31 covers at least a portion of the IDT 20, the second dielectric layer 50 covers the first sublayer 31, and the second sublayer 32 covers the second dielectric layer 50; wherein the first sublayer 31 or the second sublayer 32 is provided with a groove 40 filled with a dielectric strip 40a. Thus, the first sublayer 31 is separated from the second sublayer 32 by the second dielectric layer 50, so that the groove 40 can be provided in the first sublayer 31 or the second sublayer 32 according to the requirements of different resonators 100.

[0089] In some embodiments, the groove 40 penetrates the first sub-layer 31 or the second sub-layer 32 along a third direction, and the third direction is the thickness direction of the piezoelectric substrate 10. Figure 8 As shown in FIG. 1 , the first sublayer 31 can be covered on the IDT 20, and then a groove 40 penetrating the entire first sublayer 31 can be formed on the first sublayer 31 by etching or other methods, and a high-acoustic-velocity material can be filled in the groove 40 to form a dielectric strip 40a for adjusting the dispersion curve, and then the second dielectric layer 50 is covered on the first sublayer 31, and finally the second sublayer 32 is covered on the second dielectric layer 50. When the groove 40 is provided in the second sublayer 32 (as shown in FIG. Figure 7 As shown in the figure, the first sub-layer 31 can be first covered on the interdigital transducer 20, and then the second dielectric layer 50 can be covered on the first sub-layer 31, and finally the second sub-layer 32 can be covered on the second dielectric layer 50, and a groove 40 that runs through the entire second sub-layer 32 can be formed on the second sub-layer 32 by etching or the like, and a high acoustic velocity material can be filled to form a dielectric strip 40a for adjusting the dispersion curve.

[0090] In some embodiments, the first dielectric layer 30 and the second dielectric layer 50 are made of different materials. Thus, the first sublayer 31 and the second sublayer 32 are separated by the second dielectric layer 50 made of different materials from the first dielectric layer 30, thereby preventing corrosion to other areas when the groove 40 is formed by etching.

[0091] In some embodiments, the first dielectric layer 30 is mainly composed of silicon oxide, silicon nitride or silicon oxynitride. Exemplarily, the material of the first dielectric layer 30 can be a combination of one or more materials such as silicon oxide, silicon nitride or silicon oxynitride. It can be understood that the first dielectric layer 30 of the present application can also be made of other materials, which are not limited here, as long as they can achieve the required performance.

[0092] In some embodiments, the second dielectric layer 50 is a temperature compensation material or a high sound velocity material. Exemplarily, when the second dielectric layer 50 is a temperature compensation material, the temperature frequency characteristics of the resonator 100 can be improved. The second dielectric layer 50 can be a combination of one or more materials such as silicon oxide, silicon nitride or silicon oxynitride, which can be different from the specific material of the first dielectric layer 30. When the second dielectric layer 50 is a high sound velocity material, the sound velocity of the overall device can be moderately improved. The second dielectric layer 50 can be a high sound velocity material such as silicon nitride and aluminum nitride. It can be understood that the second dielectric layer 50 of the present application can also be made of other materials, which are not limited here, as long as the required performance can be achieved.

[0093] In some embodiments, the dielectric strip 40a has a first side surface 41 and a second side surface 42 that are arranged opposite to each other in the third direction, and the second side surface 42 faces the first surface 10a; wherein, in the second direction, the width of the first side surface 41 is greater than or equal to the width of the second side surface 42. When the width of the first side surface 41 is greater than the width of the second side surface 42, the dielectric strip 40a has a trapezoidal structure in the cross section of the resonator 100 in the side view direction, which is easier to realize in processing; when the width of the first side surface 41 is equal to the width of the second side surface 42, the dielectric strip 40a has a rectangular structure in the cross section of the resonator 100 in the side view direction, so that the formed resonator 100 has better performance.

[0094] In some embodiments, when the groove 40 passes through the first sublayer 31 or the second sublayer 32, in the second direction, the width of the first side surface 41 is 0.04λ-0.13λ, where λ is the wavelength of the sound wave. By limiting the width of the first side surface 41 of the dielectric strip 40a to the above range, it is possible to adjust the dispersion curve and make the dispersion curve flatter, thereby suppressing the transverse mode while avoiding affecting the performance of the resonator 100. Exemplarily, the width of the first side surface 41 can be 0.04λ, 0.045λ, 0.05λ, 0.055λ, 0.06λ, 0.065λ, 0.07λ, 0.075λ, 0.08λ, 0.085λ, 0.09λ, 0.095λ, 0.1λ, 0.11λ, 0.12λ, or 0.13λ, etc.

[0095] In some embodiments, the width of the first side surface 41 can be further limited to 0.05λ-0.1λ, so as to better adjust the dispersion curve and make the dispersion curve flatter, so as to better suppress the transverse mode. For example, the width of the first side surface 41 can be 0.05λ, 0.055λ, 0.06λ, 0.065λ, 0.07λ, 0.075λ, 0.08λ, 0.085λ, 0.09λ, 0.095λ or 0.1λ, etc.

[0096] In some embodiments, in the third direction, the thickness of the first sublayer 31 is greater than the thickness of the electrode finger 22. Thus, the region where the electrode finger 22 is located can be covered, and the first sublayer 31 has a sufficient thickness to realize the function of the first sublayer 31. For example, when the first sublayer 31 is made of temperature compensation material, a suitable thickness can improve the temperature frequency characteristics.

[0097] In some embodiments, when the groove 40 penetrates the first sublayer 31 or the second sublayer 32, the thickness of the first sublayer 31 in the third direction is 0.1λ-0.2λ. Limiting the thickness of the first sublayer 31 to the range of 0.1λ-0.2λ can balance the Q value and kt of the resonator 100. 2 , compensating the temperature coefficient of the resonator 100 to a suitable size.

[0098] For example, the thickness of the first sublayer 31 may be 0.1λ, 0.11λ, 0.12λ, 0.13λ, 0.14λ, 0.15λ, 0.16λ, 0.17λ, 0.18λ, 0.19λ or 0.2λ, etc.

[0099] In some embodiments, when the groove 40 penetrates the first sublayer 31 or the second sublayer 32, the thickness of the second sublayer 32 in the third direction is 0.1λ-0.3λ. Limiting the thickness of the second sublayer 32 to the range of 0.1λ-0.3λ can balance the Q value and kt of the resonator 100. 2 , compensating the temperature coefficient of the resonator 100 to a suitable size.

[0100] Exemplarily, the thickness of the second sublayer 32 may be 0.1λ, 0.11λ, 0.12λ, 0.13λ, 0.14λ, 0.15λ, 0.16λ, 0.17λ, 0.18λ, 0.19λ, 0.2λ, 0.21λ, 0.22λ, 0.23λ, 0.24λ, 0.25λ, 0.26λ, 0.27λ, 0.28λ, 0.29λ or 0.3λ, etc.

[0101] In some embodiments, the thickness of the second dielectric layer 50 is 50 nm-100 nm. If the second dielectric layer 50 is too thick, the performance of the resonator 100 will be affected, and if it is too thin, it may have an adverse effect on the positioning function of isolating the first sublayer 31 and the second sublayer 32. Therefore, the thickness of the second dielectric layer 50 is limited to the range of 50 nm-100 nm, which can separate the first sublayer 31 and the second sublayer 32 while avoiding affecting the performance of the resonator 100.

[0102] By way of example, the thickness of the second dielectric layer 50 may be 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, or 100 nm.

[0103] In some embodiments, the dielectric strip 40a is mainly composed of silicon nitride, aluminum nitride, and aluminum oxide. Exemplarily, the material of the dielectric strip 40a can be a combination of one or more materials such as silicon nitride, aluminum nitride, and aluminum oxide. It can be understood that the dielectric strip 40a of the present application can also be made of other high-sound-velocity materials, which are not limited here, as long as they can achieve the required performance.

[0104] In some embodiments, there are multiple dielectric strips 40a, and the multiple dielectric strips 40a and the multiple electrode fingers 22 are arranged in a staggered manner in the second direction. Therefore, the above arrangement can better adjust the dispersion curve and make the dispersion curve flatter, thereby achieving better suppression of the transverse mode and improving the performance of the resonator 100.

[0105] See also Figure 1a , Figure 1b , Figure 1c In some embodiments, in the second direction, the dielectric strip 40a between two electrode fingers 22 is equal to the distance between two adjacent electrode fingers 22. Therefore, by arranging the dielectric strip 40a in the center of the two electrode fingers 22, the overall asymmetry of the resonator 100 can be reduced, the formation of nonlinearity and additional heterogeneous modes can be reduced, and the performance of the resonator 100 can be improved.

[0106] See also Figures 3 to 8 In some embodiments, the resonator 100 further includes a third dielectric layer 60, and the third dielectric layer 60 covers the first dielectric layer 30. Exemplarily, the third dielectric layer 60 can be a frequency modulation layer, and the frequency modulation layer can be a single layer or a multi-layer, and different materials can be used between the multiple layers. The frequency modulation layer can be used to adjust the resonant frequency of the resonator 100. The frequency modulation layer can also play a passivation role to protect the interdigital transducer 20, which helps to prevent the interdigital transducer 20 from being damaged or corroded.

[0107] In some embodiments, the third dielectric layer 60 is mainly composed of silicon nitride, aluminum oxide or silicon oxynitride. Exemplarily, the material of the third dielectric layer 60 can be a combination of one or more materials such as silicon nitride, aluminum oxide or silicon oxynitride. It can be understood that the third dielectric layer 60 of the present application can also be made of other materials, which are not limited here, as long as they can achieve the required performance.

[0108] The present application also provides a filter, which includes the resonator 100 in any of the above embodiments. Since the resonator 100 can adjust the dispersion curve through the arrangement of the groove 40 and the dielectric strip 40a, the dispersion curve is flatter, thereby achieving better suppression of the transverse mode and improving the performance of the resonator 100.

[0109] In some embodiments, the number of resonators 100 may be multiple, and the multiple resonators 100 may be arranged as required, and the multiple resonators 100 may be two, three, four, and so on.

[0110] In some embodiments, the filter may be a ladder structure filter, which may include a plurality of series arm resonators 100 and a plurality of parallel arm resonators 100, wherein at least one of the plurality of series arm resonators 100 and the plurality of parallel arm resonators 100 is the resonator 100 in the above-mentioned embodiment.

[0111] In some other embodiments, the filter may also be other types of filters.

[0112] In addition, since the filter includes the resonator 100 , the filter has all the beneficial effects of the resonator 100 , which will not be described in detail here.

[0113] The embodiment of the present application also provides a radio frequency front-end module, which includes the filter in the above embodiment. Since the resonator 100 in the filter can adjust the dispersion curve through the arrangement of the groove 40 and the dielectric strip 40a, the dispersion curve is flatter, thereby achieving better suppression of the transverse mode and improving the performance of the resonator 100.

[0114] In some embodiments, the RF front-end module can be applied to electronic devices, which may include but are not limited to tablet computers, laptop computers, desktop computers, navigators, mobile phones, electronic watches and other electronic devices or components with wireless communication functions, which are not limited in this application.

[0115] In some embodiments, the RF front-end module may include multiple filters, and the multiple filters may be two, three, etc.

[0116] In some implementations, the RF front-end module may further include a low noise amplifier, a RF switch, a power amplifier, etc. The specific connection method thereof may refer to the prior art and will not be described in detail here.

[0117] In addition, since the RF front-end module includes the above-mentioned filter, and the filter includes the above-mentioned resonator 100, the RF front-end module has all the beneficial effects of the filter and the resonator 100, which will not be repeated here.

[0118] Those skilled in the art may combine and associate different embodiments or examples and features of different embodiments or examples described in this specification without mutual contradiction.

[0119] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed in the present application, and these modifications or replacements should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A resonator, characterized in that: include: A piezoelectric substrate having a first surface; an interdigital transducer, wherein the interdigital transducer is disposed on the first surface of the piezoelectric substrate; as well as a first dielectric layer, wherein the first dielectric layer at least covers a portion of the interdigital transducer; The interdigital transducer comprises: two bus bars disposed on the piezoelectric substrate opposite to each other along a first direction; and A plurality of electrode fingers respectively connected to the two bus bars, wherein the electrode fingers connected to the two bus bars are arranged alternately and spaced in sequence in the second direction, and a gap is provided between the electrode fingers connected to each bus bar and another bus bar, so as to form an active area between the two bus bars and a gap area located at both ends of the active area in the first direction, wherein the active area is an area where projections of the electrode fingers along the second direction overlap, the first direction intersects with the second direction, and the second direction is a propagation direction of the sound wave; Among them, the first dielectric layer is provided with a strip groove, the groove is filled with a high acoustic velocity material to form a dielectric strip, the extension direction of the dielectric strip intersects with the second direction, the dielectric strip and the electrode finger are staggered in the second direction, the active area at least includes a central area, and the projection of the dielectric strip along the second direction at least covers the projection of the central area along the second direction.

2. The resonator according to claim 1, characterized in that The active area further includes edge areas located at both ends of the central area in the first direction, and the projection of the dielectric strip in the second direction at least partially covers the projection of the edge area along the second direction.

3. The resonator according to claim 2, characterized in that The projection of the dielectric strip along the second direction covers the projection of the active area along the second direction.

4. The resonator according to claim 1, characterized in that A projection of the dielectric strip on the IDT extends from one of the bus bars to another of the bus bars.

5. The resonator according to claim 1, characterized in that The dielectric strips and the electrode fingers both extend along the first direction; and / or, The first direction is perpendicular to the second direction.

6. The resonator according to claim 1, characterized in that The groove penetrates the first dielectric layer along a third direction so that the dielectric strip contacts the first surface. The third direction is a thickness direction of the piezoelectric substrate.

7. The resonator according to claim 6, characterized in that The dielectric strip has a first side surface and a second side surface arranged opposite to each other in the third direction, and the second side surface faces the first side surface; Wherein, in the second direction, the width of the first side surface is greater than or equal to the width of the second side surface.

8. The resonator according to claim 7, characterized in that In the second direction, the width of the first side surface is 0.025λ-0.1λ or 0.045λ-0.06λ, wherein λ is the wavelength of the sound wave.

9. The resonator according to claim 6, characterized in that In the third direction, the thickness of the first dielectric layer is greater than the thickness of the electrode finger; and / or, In the third direction, the thickness of the first dielectric layer is 0.15λ-0.45λ, wherein λ is the wavelength of the sound wave.

10. The resonator according to claim 1, characterized in that The resonator further comprises a second dielectric layer, the first dielectric layer comprises a first sublayer and a second sublayer, the first sublayer at least covers a portion of the interdigital transducer, the second dielectric layer covers the first sublayer, and the second sublayer covers the second dielectric layer; The first sublayer or the second sublayer is provided with the groove filled with the dielectric strip.

11. The resonator according to claim 10, characterized in that The groove penetrates the first sub-layer or the second sub-layer along a third direction, and the third direction is a thickness direction of the piezoelectric substrate.

12. The resonator according to claim 11, characterized in that The dielectric strip has a first side surface and a second side surface arranged opposite to each other in the third direction, and the second side surface faces the first side surface; Wherein, in the second direction, the width of the first side surface is greater than or equal to the width of the second side surface.

13. The resonator according to claim 12, characterized in that In the second direction, the width of the first side surface is 0.04λ-0.13λ or 0.05λ-0.1λ, wherein λ is the wavelength of the sound wave.

14. The resonator according to claim 13, characterized in that In the third direction, the thickness of the first sublayer is greater than the thickness of the electrode finger; and / or, In the third direction, the thickness of the first sublayer is 0.1λ-0.2λ, wherein λ is the wavelength of the sound wave; and / or, In the third direction, the thickness of the second sublayer is 0.1λ-0.3λ, wherein λ is the wavelength of the sound wave.

15. The resonator according to claim 10, characterized in that The thickness of the second dielectric layer is 50nm-100nm.

16. The resonator according to claim 10, characterized in that The second dielectric layer is a temperature compensation material or a high sound velocity material; and / or, The first dielectric layer and the second dielectric layer are made of different materials.

17. The resonator according to any one of claims 1 to 16, characterized in that: The dielectric strip has a first side surface and a second side surface which are arranged opposite to each other in a third direction, and a third side surface connected to the first side surface and the second side surface, the second side surface faces the first side surface, and the third direction is a thickness direction of the piezoelectric substrate; The first side surface and the second side surface both extend along the second direction, and an angle between the third side surface and the first side surface is 70°-90°.

18. The resonator according to any one of claims 1 to 16, characterized in that: The dielectric strips are mainly composed of silicon nitride, aluminum nitride and aluminum oxide.

19. The resonator according to any one of claims 1 to 16, characterized in that: There are multiple dielectric strips, and the multiple dielectric strips and the multiple electrode fingers are sequentially arranged in an alternating manner in the second direction.

20. The resonator according to claim 19, characterized in that In the second direction, the dielectric strip between two of the electrode fingers is equal to the distance between two adjacent electrode fingers.

21. The resonator according to claim 2, characterized in that The sound velocity of the central area is V1, the sound velocity of the edge area is V2, and the sound velocity of the gap area is V3; Among them, V3>V1>V2.

22. The resonator according to any one of claims 1 to 16, characterized in that The first dielectric layer is a temperature compensation layer, which is used to adjust the frequency temperature coefficient of the resonator; and / or, The first dielectric layer is mainly composed of silicon oxide, silicon nitride or silicon oxynitride; and / or, The interdigital transducer further comprises a piston structure, and the piston structure is arranged at the end of the electrode finger located in the edge area.

23. The resonator according to any one of claims 1 to 16, characterized in that The resonator further includes a third dielectric layer, and the third dielectric layer covers the first dielectric layer.

24. The resonator according to claim 23, characterized in that The third dielectric layer is mainly composed of silicon nitride, aluminum oxide or silicon oxynitride.

25. A filter, characterized in that: Comprising a resonator as claimed in any one of claims 1-24.

26. A radio frequency front-end module, characterized in that: Comprising a filter as claimed in claim 25.

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