Film surface acoustic wave resonator and filter

Abstract

The utility model discloses a film surface acoustic wave resonator and a film surface acoustic wave filter, and relates to the field of semiconductor devices, at least one intermediate layer is inserted into at least one dielectric layer of the film surface acoustic wave resonator, so that the physical strength of the dielectric layer inserted with the intermediate layer can be improved, and the relatively thin dielectric layer has a relatively good fracture prevention effect; and for the relatively thick dielectric layer, the middle layer can help to improve the flatness and the surface smoothness in the material growth or sputtering process, so that the relatively thick dielectric layer can avoid relatively large roughness in the forming process. And the thickness of each inserted middle layer is less than 0.2 lambda, so that the propagation of a main acoustic mode is not directly influenced, but for other miscellaneous modes, due to the difference of acoustic propagation paths, reflection is generated at the positions of the middle layers to a certain extent, so that the resonance condition of the miscellaneous modes is destroyed, and the energy dissipation is reduced. And the energy is further limited in the reflection region, so that the Q value of the resonator can be further improved.

Description

Technical Field

[0001] The present application relates to the technical field of semiconductor devices, and in particular to a thin film surface acoustic wave resonator and a filter. 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 radio frequency. Among them, surface acoustic wave is an elastic wave with energy concentrated near the surface.

[0003] In the current surface acoustic wave product design, TF-SAW resonator (thin film surface acoustic wave resonator) is a surface acoustic wave resonator design structure that has been widely used in recent years. A piezoelectric film layer is arranged on the substrate, and a cross-finger electrode is arranged on the side of the piezoelectric film layer away from the substrate. It should be noted that in addition to the above basic features, the TF-SAW resonator can also include any number of different dielectric layers such as insertion layer, protective layer, adjustment layer, temperature compensation layer, speed change layer, etc. below the piezoelectric film layer and above the substrate to form a stacked layer (Stack) structure, thereby achieving a variety of different technical effects.

[0004] For TF-SAW resonators, the processing technology and quality of the stacked layer structure above the substrate is a technical problem that needs to be solved. With the increase in the number of layers and the application of different materials, as well as the actual situation that each dielectric layer is relatively thin (usually the thickness of each dielectric layer is between tens of nanometers and hundreds of nanometers), indicators such as the film quality of each dielectric layer, the bonding strength between the stacked layer structures, and the mechanical strength of the substrate will have a great impact on the yield and reliability of the final product.

[0005] Therefore, how to optimize the structure of the thin film surface acoustic wave resonator to improve the process quality of the multi-layer substrate and optimize its device performance is a technical problem that needs to be solved urgently by those skilled in the art. Utility Model Content

[0006] In view of the above problems, the present application provides a thin film surface acoustic wave resonator and filter to achieve the purpose of improving the device yield, reliability and performance. The specific solution is as follows:

[0007] In a first aspect, the present application provides a thin film surface acoustic wave resonator, the thin film surface acoustic wave resonator comprising:

[0008] A substrate and a piezoelectric film layer are arranged opposite to each other in a first direction, wherein the first direction is perpendicular to a plane where the substrate is located;

[0009] An interdigitated electrode located on a side of the substrate facing away from the piezoelectric film layer;

[0010] At least one dielectric layer located between the substrate and the piezoelectric film layer, the at least one dielectric layer comprising N sub-dielectric layers stacked in the first direction, N ≥ 2, and N is a positive integer;

[0011] The intermediate layer is located between two adjacent sub-dielectric layers, and the thickness of the intermediate layer in the first direction is less than 0.2λ, where λ is the wavelength of the sound wave propagating in the thin film surface acoustic wave resonator.

[0012] In a possible implementation, the intermediate layer is an intermediate layer of silicon nitride, aluminum nitride or polysilicon.

[0013] In a possible implementation, the at least one dielectric layer includes a temperature compensation layer.

[0014] In a possible implementation, the at least one dielectric layer includes: a temperature compensation layer and a first reflective layer stacked in the first direction;

[0015] The temperature compensation layer is disposed adjacent to the piezoelectric film layer, and the first reflective layer is disposed adjacent to the substrate.

[0016] In a possible implementation, the intermediate layer is disposed in the temperature compensation layer and / or the intermediate layer is disposed in the first reflection layer.

[0017] In a possible implementation, the at least one dielectric layer includes: a temperature compensation layer, a first reflection layer, and a second reflection layer stacked in the first direction, and a sound propagation velocity in the first reflection layer is different from a sound propagation velocity in the second reflection layer;

[0018] The temperature compensation layer is disposed adjacent to the piezoelectric film layer, and the first reflective layer is located between the temperature compensation layer and the substrate;

[0019] The second reflective layer is located between the temperature compensation layer and the first reflective layer, or the second reflective layer is located between the first reflective layer and the substrate.

[0020] In a possible implementation, the intermediate layer is disposed in the temperature compensation layer and / or the intermediate layer is disposed in the first reflection layer and / or the intermediate layer is disposed in the second reflection layer.

[0021] In a possible implementation, when M dielectric layers are arranged between the substrate and the piezoelectric film layer, M≥2, and M is a positive integer, the number of intermediate layers arranged in the i-th dielectric layer is different from the number of intermediate layers arranged in the j-th dielectric layer, i≤M, j≤M, and i≠j.

[0022] In a possible implementation, the intermediate layer is also located between any two film layers between the substrate and the piezoelectric film layer.

[0023] In one possible implementation, the interdigitated electrode includes a bus bar, which includes a first bus bar and a second bus bar arranged relative to each other in a second direction, and a first electrode finger located on the first bus bar and a second electrode finger located on the second bus bar; the first bus bar and the second bus bar have the same length extension direction and both extend along a third direction, the second direction and the third direction are parallel to the plane where the substrate is located, and the second direction and the third direction intersect.

[0024] In a possible implementation, the interdigital electrode further includes:

[0025] A plurality of first dummy electrode fingers are located on the first bus bar, and a plurality of second dummy electrode fingers are located on the second bus bar, wherein the length extension direction of the dummy electrode fingers is parallel to the second direction.

[0026] In a possible implementation, the thin film surface acoustic wave resonator further includes:

[0027] A reflection grating is located at at least one end of the interdigital electrode along the propagation direction of the main acoustic mode.

[0028] A second aspect of the present application provides a filter, wherein the filter comprises the thin film surface acoustic wave resonator described in any one of the above items.

[0029] By means of the above technical solution, the thin film surface acoustic wave resonator and filter provided by the present application can improve the physical strength of the dielectric layer with the intermediate layer inserted by inserting at least one intermediate layer into at least one dielectric layer of the thin film surface acoustic wave resonator, and has a better effect of avoiding cracking for the thinner dielectric layer; and for the relatively thicker dielectric layer, the intermediate layer can help the material growth or sputtering process to improve the flatness and surface smoothness, so that the thicker dielectric layer can avoid greater roughness during formation. And the thickness of each inserted intermediate layer is less than 0.2λ, so it has no direct impact on the propagation of the main acoustic mode, but for other miscellaneous modes, due to the difference in the sound propagation path, reflection will occur at the intermediate layer position to a certain extent, so as to destroy its resonance condition to reduce the dissipation of energy, and further limit the energy to the reflection area, so that the Q value of the resonator can be further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The above and other features, advantages and aspects of the embodiments of the present disclosure will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. Throughout the accompanying drawings, the same or similar reference numerals represent the same or similar elements. It should be understood that the drawings are schematic and the originals and elements are not necessarily drawn to scale.

[0031] Figure 1 A schematic structural diagram of a thin film surface acoustic wave resonator provided in an embodiment of the utility model;

[0032] Figure 2 A schematic structural diagram of another thin film surface acoustic wave resonator provided by an embodiment of the utility model;

[0033] Figure 3 A schematic structural diagram of another thin film surface acoustic wave resonator provided in an embodiment of the utility model;

[0034] Figure 4 A schematic structural diagram of another thin film surface acoustic wave resonator provided in an embodiment of the utility model;

[0035] Figure 5 A schematic structural diagram of another thin film surface acoustic wave resonator provided in an embodiment of the utility model;

[0036] Figure 6 A schematic structural diagram of another thin film surface acoustic wave resonator provided in an embodiment of the utility model;

[0037] Figure 7 A schematic structural diagram of another thin film surface acoustic wave resonator provided in an embodiment of the utility model;

[0038] Figure 8 A schematic structural diagram of another thin film surface acoustic wave resonator provided in an embodiment of the utility model;

[0039] Fig. 9 A schematic structural diagram of another thin film surface acoustic wave resonator provided in an embodiment of the utility model;

[0040] Fig.10 A schematic structural diagram of another thin film surface acoustic wave resonator provided in an embodiment of the utility model;

[0041] Fig.11 A schematic structural diagram of another thin film surface acoustic wave resonator provided in an embodiment of the utility model;

[0042] Fig.12 A schematic structural diagram of another thin film surface acoustic wave resonator provided in an embodiment of the utility model;

[0043] Fig.13A schematic structural diagram of another thin film surface acoustic wave resonator provided in an embodiment of the utility model;

[0044] Fig.14 A schematic diagram of a top view of a thin film surface acoustic wave resonator provided in an embodiment of the utility model;

[0045] Fig.15 A schematic diagram of a top view of another thin film surface acoustic wave resonator provided in an embodiment of the utility model;

[0046] Fig.16 A schematic diagram of a top view of another thin film surface acoustic wave resonator provided in an embodiment of the utility model;

[0047] Fig.17 A schematic diagram of the effect of clutter suppression in a Y curve provided by an embodiment of the utility model;

[0048] Fig.18 A schematic diagram of the effect of improving the Q value in a Y curve provided by an embodiment of the utility model;

[0049] Fig.19 A schematic diagram of the effect of clutter suppression in another Y curve provided by an embodiment of the utility model;

[0050] Fig. 20 A schematic diagram of another effect of improving the Q value in a Y curve provided by an embodiment of the utility model;

[0051] Fig.21 A schematic diagram of the effect of clutter suppression in another Y curve provided by an embodiment of the utility model;

[0052] Fig. 22 This is a schematic diagram of the effect of improving the Q value in another Y curve provided by an embodiment of the utility model. DETAILED DESCRIPTION

[0053] The following describes the embodiments of the present application in conjunction with the drawings in the embodiments of the present application. The terms used in the implementation method section of the present application are only used to explain the specific embodiments of the present application, and are not intended to limit the present application.

[0054] The embodiments of the present application are described below in conjunction with the accompanying drawings. Those skilled in the art will appreciate that, with the development of technology and the emergence of new scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0055] Surface acoustic wave resonators and filters are acoustic devices widely used in the field of radio frequency. They combine low insertion loss and good suppression performance, and are relatively small in size. They are used to filter out interference from different frequency signals, attenuate some frequency components, and only allow specified frequency components. They are the technical basis for the application of wireless spectrum as a non-renewable scarce resource. The specific principle can be simply understood as based on the piezoelectric properties of piezoelectric materials, using input and output transducers such as interdigital transducers to convert electrical signals into mechanical energy, and then convert them into electrical signals after processing, so as to amplify the required signals, filter out noise signals and improve signal quality. They are widely used in various wireless communication equipment.

[0056] At present, filters are mainly divided into SAW filters and BAW (Bulk Acoustic Wave) filters. Surface acoustic waves are an elastic wave that is generated and propagated on the surface of a piezoelectric substrate with piezoelectric properties, and whose amplitude decreases rapidly as the depth of the piezoelectric substrate increases. For SAW filters, their manufacturing cost is much lower than that of BAW filters. They are used in low-frequency bands, have low insertion loss and good suppression, and are temperature sensitive.

[0057] At the same time, it should be noted that SAW filters also have corresponding limitations. One of them is that they are easily affected by temperature changes. When the temperature rises, the stiffness of the base material tends to decrease and the sound speed will also decrease. It can also be said that SAW filters have the defect of temperature drift, that is, the frequency will drift with the operating temperature. Therefore, based on the traditional SAW filter, the TC-SAW filter, that is, the temperature-compensated SAW filter, is produced accordingly. It mainly utilizes the temperature compensation layer (such as SiO2 layer) and the piezoelectric film layer. The opposite temperature elastic characteristics realize compensation for the temperature drift characteristics.

[0058] It should be further explained that SAW filters also have product designs such as TF-SAW filters (thin film surface acoustic wave filters), in which the design of the filters often uses resonators as basic units, which can form the corresponding topology and amplify the specified frequency component signal.

[0059] Among them, the TF-SAW resonator (thin film surface acoustic wave resonator) is a surface acoustic wave resonator design structure that has been widely used in recent years. A piezoelectric film layer is arranged on the substrate, and a cross-finger electrode is arranged on the side of the piezoelectric film layer away from the substrate. It should be noted that in addition to the above basic characteristics, the TF-SAW resonator can also include any number of different dielectric layers such as an insertion layer, a protective layer, an adjustment layer, a temperature compensation layer, a speed change layer, etc. below the piezoelectric film layer and above the substrate to form a stacked layer structure, thereby achieving a variety of different technical effects.

[0060] For TF-SAW resonators, the processing technology and quality of the stacked layer structure above the substrate is a technical problem that needs to be solved. With the increase in the number of layers and the application of different materials, as well as the actual situation that each dielectric layer is relatively thin (usually the thickness of each dielectric layer is between tens of nanometers and hundreds of nanometers), indicators such as the film quality of each dielectric layer, the bonding strength between the stacked layer structures, and the mechanical strength of the substrate will have a great impact on the yield and reliability of the final product. Therefore, how to optimize the structure of the thin film surface acoustic wave resonator to achieve the improvement of the process quality of the multi-layer substrate and improve its device performance is a technical problem that technical personnel in this field need to solve urgently.

[0061] Based on this, a thin film surface acoustic wave resonator and filter are provided in the embodiment of the utility model. By inserting at least one intermediate layer into at least one dielectric layer of the thin film surface acoustic wave resonator, the physical strength of each dielectric layer can be improved. For thinner dielectric layers, it has a better effect of avoiding cracking; and for relatively thicker dielectric layers, the intermediate layer can help the material growth or sputtering process to improve the flatness and surface smoothness, so that the thicker dielectric layer can avoid greater roughness during formation, thereby reducing the difficulty of trimming work, thereby comprehensively improving the yield and reliability of the final product. And the thickness of each inserted intermediate layer is less than 0.2λ, λ is the wavelength of the sound wave propagating in the thin film surface acoustic wave resonator, so it has no direct impact on the propagation of the main acoustic mode, but for other miscellaneous modes, due to the difference in the sound propagation path, it will be reflected at the intermediate layer position to a certain extent, thereby destroying its resonance condition to reduce the dissipation of energy, and further confining the energy in the reflection area, so that the Q value of the resonator can be further improved.

[0062] refer to Figure 1 , Figure 1 The schematic diagram of the structure of a thin film surface acoustic wave resonator provided by an embodiment of the utility model, the thin film surface acoustic wave resonator provided by an embodiment of the utility model comprises:

[0063] The substrate 11 and the piezoelectric film layer 12 are arranged relatively to each other in a first direction X, and the first direction X is perpendicular to the plane where the substrate 11 is located, or the first direction X is perpendicular to the plane where the piezoelectric film layer 12 is located, that is, under normal circumstances, the plane where the piezoelectric film layer 12 is located is parallel to the plane where the substrate 11 is located.

[0064] The interdigital electrodes 13 are located on a side of the substrate 11 away from the piezoelectric film layer 12 .

[0065] At least one dielectric layer 14 is located between the substrate 11 and the piezoelectric film layer 12, and the at least one dielectric layer 14 includes N sub-dielectric layers (sub-dielectric layer 141 and sub-dielectric layer 142 for illustration) stacked in the first direction X, N≥2, and N is a positive integer.

[0066] The intermediate layer 15 is located between two adjacent sub-dielectric layers, and the thickness of the intermediate layer 15 in the first direction X is less than 0.2λ, where λ is the wavelength of the acoustic wave propagating in the thin film surface acoustic wave resonator.

[0067] Specifically, in the embodiment of the utility model, the substrate 11 is used as a supporting structure, and its material can be selected from lithium tantalate material, lithium niobate material, aluminum nitride material, sapphire material, spinel material, silicon material, silicon carbide material or quartz material. The piezoelectric film layer 12 is made of piezoelectric material, and its material can be selected from lithium tantalate LT material or lithium niobate LN material. The interdigital electrode 13 is usually made of a metal material, and its material can be selected from a material with a low resistivity such as Cu material, Al material, Au material, Ti material, Cr material, Pt material, etc.

[0068] The at least one dielectric layer 14 between the substrate 11 and the piezoelectric film layer 12 may be any number of dielectric layers such as an insertion layer, a protective layer, an adjustment layer, a temperature compensation layer, a speed-changing layer, etc., forming a stack structure, thereby achieving a variety of different technical effects.

[0069] In the embodiment of the utility model, at least one intermediate layer 15 is inserted into at least one dielectric layer 14 of the thin film surface acoustic wave resonator, on the one hand, the physical strength of the dielectric layer 14 with the intermediate layer 15 inserted can be improved, thereby improving the film stability of the stacked layer structure; on the other hand, since most of the dielectric layers 14 are prepared by ion sputtering, in layman's terms, the dielectric layer is formed by ion sputtering on a plane, because the position of ion sputtering is random, the thicker the dielectric layer 14 is to be made, the higher the randomness will be, and the surface smoothness of the dielectric layer 14 finally made will be poor. Obviously, when at least one intermediate layer 15 is inserted in the middle of the dielectric layer 14, the flatness and surface smoothness of each sub-dielectric layer of the dielectric layer 14 can be increased, so that the thicker dielectric layer 14 can avoid greater roughness during formation, thereby reducing the difficulty of trimming work, and for the thinner dielectric layer 14, when at least one intermediate layer 15 is inserted in the middle of the dielectric layer 14, there is a better effect of avoiding cracking, thereby comprehensively improving the yield and reliability of the final product.

[0070] It should be noted that when the number of the intermediate layers 15 is greater than or equal to two, the thickness of any intermediate layer 15 in the first direction X is less than 0.2λ.

[0071] Furthermore, when the thickness of the intermediate layer 15 is less than 0.2λ, since the propagation direction of the main acoustic mode and the wave vibration direction are perpendicular to the plane where the intermediate layer 15 is located, the penetration thickness is less than 0.2λ, so the setting of the intermediate layer 15 will not affect the performance of the thin film surface acoustic wave resonator. As for other clutter, these clutter propagates in all directions. Because of the angle problem, the thickness of these clutter penetration is likely to be greater than 0.2λ. In this case, these clutter will be restricted and suppressed, thereby improving the Q value of the thin film surface acoustic wave resonator. In general, for other clutter, due to the difference in the sound propagation path, it will be reflected to a certain extent at the position of the intermediate layer 15, thereby destroying its resonance condition to reduce the dissipation of energy, and further limiting the energy in the reflection area, so that the Q value of the thin film surface acoustic wave resonator can be further improved.

[0072] In an optional embodiment of the present invention, the material of the intermediate layer 15 is silicon nitride material, aluminum nitride material or polysilicon material.

[0073] Specifically, in the embodiments of the present invention, since silicon nitride material, aluminum nitride material or polycrystalline silicon material is a material with relatively high strength and relatively stable performance, when silicon nitride material, aluminum nitride material or polycrystalline silicon material is selected to prepare the intermediate layer 15, it is obvious that when at least one intermediate layer 15 is inserted into at least one dielectric layer 14 of the thin film surface acoustic wave resonator, the physical strength of the dielectric layer 14 with the intermediate layer 15 inserted can be improved, thereby improving the film layer stability of the stacked layer structure.

[0074] It should be noted that the type and purity of the polysilicon material are not limited in the embodiments of the present invention, because it is not required to exert electrical performance characteristics, so various similar polysilicon materials are acceptable.

[0075] In an optional embodiment of the present invention, the dielectric layer 14 is described by taking a temperature compensation layer as an example.

[0076] Specifically, in the embodiment of the utility model, the material of the temperature compensation layer is preferably SiO2 material, which can compensate for the temperature drift effect of the metal material of the interdigital electrode 13 and reduce the impact of temperature changes on device performance, especially the resonant frequency and passband range.

[0077] refer to Figure 2 , Figure 2 The schematic diagram of the structure of another thin film surface acoustic wave resonator provided by an embodiment of the utility model, at least one dielectric layer 14 includes: a temperature compensation layer 16 and a first reflection layer 17 stacked in the first direction X.

[0078] Specifically, in the embodiment of the present utility model, the temperature compensation layer 16 is disposed adjacent to the piezoelectric film layer 12, and the first reflective layer 17 is disposed adjacent to the substrate 11, that is, in the direction from the substrate 11 to the piezoelectric film layer 12, Figure 2 The thin film surface acoustic wave resonator shown includes a substrate 11, a first reflection layer 17, a temperature compensation layer 16, a piezoelectric film layer 12 and interdigital electrodes 13. That is to say, the added first reflection layer 17 is generally located below the temperature compensation layer 16, and the first reflection layer 17 can be made of a material with a higher sound velocity, such as aluminum nitride material, aluminum oxide material, silicon nitride material, silicon oxynitride material, silicon carbide material or trap-rich silicon material (trap-rich Si), etc.

[0079] It should be noted that the sound propagation velocity in the first reflective layer 17 is higher than the sound propagation velocity in the piezoelectric film layer 12 .

[0080] like Figure 2 As shown, as a typical application example of the technical solution of the utility model, an intermediate layer 15 is added in the middle of the temperature compensation layer 16, and the thickness of the intermediate layer 15 in the first direction X is less than 0.2λ. At this time, the temperature compensation layer 16 including the intermediate layer 15 simultaneously assumes the functions of temperature compensation and low sound velocity layer.

[0081] refer to Figure 3 , Figure 3 A schematic diagram of the structure of another thin film surface acoustic wave resonator provided in an embodiment of the utility model, wherein at least one dielectric layer 14 includes: a temperature compensation layer 16, a first reflection layer 17 and a second reflection layer 18 stacked in the first direction X, and the sound propagation velocity in the first reflection layer 17 is different from the sound propagation velocity in the second reflection layer 18.

[0082] Specifically, in the embodiment of the present utility model Figure 2 A second reflection layer 18 can be further provided on the basis of the structure of the thin film surface acoustic wave resonator shown. The second reflection layer 18 can be located between the temperature compensation layer 16 and the first reflection layer 17, or between the first reflection layer 17 and the substrate 11. That is to say, the second reflection layer 18 can be located above or below the first reflection layer 17. In the embodiment of the utility model, the second reflection layer 18 is located between the temperature compensation layer 16 and the first reflection layer 17 as an example for explanation.

[0083] The second reflective layer 18 can be made of a material with a low acoustic velocity, such as silicon oxide, silicon oxynitride, tantalum oxide, or glass.

[0084] It should be noted that the sound propagation velocity in the second reflective layer 18 is lower than the sound propagation velocity in the piezoelectric film layer 12 .

[0085] Furthermore, it should be noted that when the positions of the first reflective layer 17 and the second reflective layer 18 can be interchanged, the number of layers can be further increased, but it is necessary to ensure that there is a difference in the sound velocity of the two adjacent reflective layers. The change in sound velocity can reflect the mechanical wave energy at the material interface, thereby reducing energy dissipation and suppressing clutter, so as to improve the Q value of the thin film surface acoustic wave resonator.

[0086] It should be further explained that, for the reflection layer located at the bottom or the reflection layer closest to the substrate 11, its thickness in the first direction X is at least greater than 1λ to achieve the effect of limiting the sound waves. Figure 2 As shown, only the first reflective layer 17 is included, which is disposed adjacent to the substrate 11, so Figure 2 The thickness of the first reflective layer 17 in the thin film surface acoustic wave resonator structure shown needs to be at least greater than 1λ; Figure 3 As shown, the first reflective layer 17 and the second reflective layer 18 are included, but the first reflective layer 17 is closer to the substrate 11 than the second reflective layer 18. Figure 3 The thickness of the first reflective layer 17 in the thin film surface acoustic wave resonator structure shown needs to be at least greater than 1λ. When the positions of the first reflective layer 17 and the second reflective layer 18 are interchanged, it is obvious that the thickness of the second reflective layer 18 needs to be at least greater than 1λ.

[0087] In an optional embodiment of the present invention, Figure 1-Figure 3 The thin film surface acoustic wave resonator shown in the figure is only an example in which an intermediate layer 15 is inserted into the temperature compensation layer 16. Figure 4 , Figure 4 A schematic diagram of the structure of another thin film surface acoustic wave resonator provided by the embodiment of the utility model, referring to Figure 5 , Figure 5 A schematic diagram of the structure of another thin film surface acoustic wave resonator provided by an embodiment of the utility model is shown in FIG. Figure 4 As shown, an intermediate layer 15 is inserted into the first reflective layer 17 to divide the first reflective layer 17 into two sub-reflective layers; Figure 5 As shown, an intermediate layer 15 is inserted into the second reflective layer 18 to divide the second reflective layer 18 into two sub-reflective layers.

[0088] In an optional embodiment of the present invention, Figure 2 As shown, when two dielectric layers, namely, a temperature compensation layer 16 and a first reflection layer 17, are disposed between the substrate 11 and the piezoelectric film layer 12, Figure 6 , Figure 6The schematic structural diagram of another thin film surface acoustic wave resonator provided for the embodiment of the utility model shows that the intermediate layer 15 can be inserted into the temperature compensation layer 16 at the same time, and the intermediate layer 15 can also be inserted into the first reflection layer 17 to further increase the technical effect of the technical solution of the utility model.

[0089] In an optional embodiment of the present invention, Figure 3 As shown, when three dielectric layers are arranged between the substrate 11 and the piezoelectric film layer 12, namely, the temperature compensation layer 16, the first reflection layer 17 and the second reflection layer 18, Figure 7 , Figure 7 A structural schematic diagram of another thin film surface acoustic wave resonator provided for an embodiment of the utility model shows that an intermediate layer 15 can be inserted into the temperature compensation layer 16, an intermediate layer 15 can also be inserted into the first reflection layer 17, and an intermediate layer 15 can also be inserted into the second reflection layer 18, so as to further increase the technical effect of the technical solution of the utility model.

[0090] In an optional embodiment of the present invention, Figure 1-Figure 7 In the thin film surface acoustic wave resonator shown in FIG. 1 , whether the intermediate layer 15 is inserted into one dielectric layer 14 or the intermediate layer 15 is inserted into two or three dielectric layers 14 at the same time, the number of the inserted intermediate layers 15 is described by taking one layer as an example. Obviously, multiple intermediate layers 15 can also be inserted into the same dielectric layer 14. Figure 8 , Figure 8 A schematic diagram of the structure of another thin film surface acoustic wave resonator provided in an embodiment of the utility model, Figure 8 In the thin film surface acoustic wave resonator shown, two intermediate layers 15 are inserted into the temperature compensation layer 16, and the temperature compensation layer 16 is divided into three sub-membrane layers from top to bottom. This design can also further enhance the technical effect of the technical solution of the utility model.

[0091] In an optional embodiment of the present utility model, reference Fig. 9 , Fig. 9 A schematic diagram of the structure of another thin film surface acoustic wave resonator provided by the embodiment of the utility model, referring to Fig.10 , Fig.10 A schematic diagram of the structure of another thin film surface acoustic wave resonator provided by the embodiment of the utility model, referring to Fig.11 , Fig.11 A schematic diagram of the structure of another thin film surface acoustic wave resonator provided by an embodiment of the utility model, when the thin film surface acoustic wave resonator does not include a temperature compensation layer 16, and only includes a first reflection layer 17 and a second reflection layer 18, an intermediate layer 15 is inserted into at least one reflection layer, such as Fig. 9 As shown, the intermediate layer 15 is inserted into the first reflective layer 17, and the intermediate layer 15 is not inserted into the second reflective layer 18; Fig.10 As shown, the intermediate layer 15 is inserted into the second reflective layer 18, and the intermediate layer 15 is not inserted into the first reflective layer 17; Fig.11 As shown, the intermediate layer 15 is inserted into both the first reflective layer 17 and the second reflective layer 18 .

[0092] It should be noted that Figure 9-11 The number of the intermediate layers 15 inserted into the thin film surface acoustic wave resonator shown is not limited, and it is obvious that multiple intermediate layers 15 can be inserted into the same reflective layer.

[0093] When the intermediate layer 15 is provided in at least one reflective layer (a high sound velocity layer or a low sound velocity layer), the following advantages can be brought about (at this time, more materials can be additionally selected, as long as there is a significant difference in sound velocity with the material of the reflective layer). Since the thickness of the intermediate layer 15 is less than 0.2λ, it has no direct impact on the propagation of the main acoustic mode. However, for other heterogeneous modes, due to the difference in the sound propagation path, reflection will occur at the intermediate layer position to a certain extent, thereby destroying its resonance condition to reduce energy dissipation, and further confining the energy within the reflection area, thereby further improving the Q value of the resonator.

[0094] In an optional embodiment of the utility model, when M dielectric layers 14 are arranged between the substrate 11 and the piezoelectric film layer 12, M≥2, and M is a positive integer, the number of intermediate layers 15 inserted in the i-th dielectric layer is different from the number of intermediate layers 15 inserted in the j-th dielectric layer, i≤M, j≤M, and i≠j.

[0095] Exemplary, reference Fig.12 , Fig.12 A schematic structural diagram of another thin film surface acoustic wave resonator provided for an embodiment of the present invention, wherein two dielectric layers are arranged between the substrate 11 and the piezoelectric film layer 23, namely a first dielectric layer 14A and a second dielectric layer 14B, wherein an intermediate layer 15 is inserted in the first dielectric layer 14A, and two intermediate layers 15 are inserted in the second dielectric layer 14B. Taking into account the particularities of the dielectric layers 14 with different functions, a variety of different structural designs are used in the embodiment of the present invention to further increase the technical effect of the technical solution of the present invention.

[0096] In an optional embodiment of the present invention, the intermediate layer 15 is also provided between any two film layers between the substrate 11 and the piezoelectric film layer 12. Fig.13 , Fig.13 A schematic structural diagram of another thin film surface acoustic wave resonator provided in an embodiment of the utility model comprises: a substrate 11 , a first reflection layer 17 , a second reflection layer 18 , an intermediate layer 15 , a temperature compensation layer 16 and a piezoelectric film layer 12 .

[0097] An intermediate layer 15 is inserted into the temperature compensation layer 16 .

[0098] Specifically, in the embodiment of the utility model, the intermediate layer 15 located between the second reflective layer 18 and the temperature compensation layer 16 serves as a bonding auxiliary layer to help improve the bonding strength between the second reflective layer 18 and the temperature compensation layer 16, thereby reducing the difficulty of the bonding process. Therefore, for the selection of multi-layer POI substrate materials with certain bonding difficulties, the setting of the intermediate layer 15 can be used to improve the effect of the bonding process.

[0099] Obviously, an intermediate layer 15 may be disposed between the substrate 11 and the first reflective layer 17 , and an intermediate layer 15 may be disposed between the first reflective layer 17 and the second reflective layer 18 , which will not be described one by one here.

[0100] It should be noted that the present technical solution can further add different functional layers formed by various materials on the basis of the above, and the principles are the same, so they will not be described in detail.

[0101] In an optional embodiment of the present utility model, reference Fig.14 , Fig.14 A schematic diagram of a top view of a thin film surface acoustic wave resonator provided in an embodiment of the utility model, wherein the interdigitated electrode 13 includes a bus bar, the bus bar includes a first bus bar 131 and a second bus bar 132 arranged opposite to each other in a second direction Y, and a first electrode finger 133 located on the first bus bar 131 and a second electrode finger 134 located on the second bus bar 132; the first bus bar 131 and the second bus bar 132 have the same length extension direction, both extending along a third direction Z, the second direction Y and the third direction Z are parallel to the plane where the substrate 11 is located, and the second direction Z and the third direction Y intersect; Fig.14 The description is made by taking the example that the second direction Y is perpendicular to the third direction Z.

[0102] refer to Fig.15 , Fig.15 This is a schematic diagram of a top view of another thin film surface acoustic wave resonator provided by an embodiment of the utility model. The interdigitated electrode 13 provided by the embodiment of the utility model further includes:

[0103] A plurality of first dummy electrode fingers 135 are located on the first bus bar 131, and a plurality of second dummy electrode fingers 136 are located on the second bus bar 132, wherein the length extension direction of the dummy electrode fingers is parallel to the second direction Y, the plurality of first dummy electrode fingers 135 and the plurality of first electrode fingers 133 on the first bus bar 131 are arranged in sequence and spaced apart in the third direction Z, the plurality of second dummy electrode fingers 136 and the plurality of second electrode fingers 134 on the second bus bar 132 are arranged in sequence and spaced apart in the third direction Z, and in the second direction Y, the first electrode fingers 133 on the first bus bar 131 and the second dummy electrode fingers 136 on the second bus bar 132 are arranged opposite to each other, and there is a gap between them, and the first dummy electrode fingers 135 on the first bus bar 131 and the second electrode fingers 134 on the second bus bar 132 are arranged opposite to each other, and there is also a gap between them.

[0104] That is to say, in the embodiment of the present utility model, the interdigital electrode 13 can be an interdigital electrode without dummy electrode fingers, or can be an interdigital electrode without dummy electrode fingers. Fig.15 The interdigitated electrodes with dummy electrode fingers shown in the figure, when the interdigitated electrodes 13 are provided with dummy electrode fingers, the provision of the dummy electrode fingers can also play the effect of suppressing clutter and improving the quality factor of the surface acoustic wave resonator.

[0105] refer to Fig.16 , Fig.16 A schematic diagram of a top view of another thin film surface acoustic wave resonator provided in an embodiment of the utility model. The thin film surface acoustic wave resonator provided in an embodiment of the utility model further includes:

[0106] The reflection grating 19 located at at least one end of the interdigital electrode 13 along the third direction Z. It should be noted that in the embodiment of the utility model, the reflection grating 19 is provided at both ends of the interdigital electrode 13 along the third direction Z. The third direction Z can also be understood as the propagation direction of the main acoustic mode of the thin film surface acoustic wave resonator.

[0107] Specifically, in the embodiment of the utility model, a reflection grating 19 can be set at at least one end of the interdigitated electrode 13 along the third direction Z to reflect the sound waves back to the resonance area, allowing the sound waves to continue to resonate in the resonance area, thereby forming a better resonance effect and mode, and improving the transmission performance of the surface acoustic wave resonator.

[0108] In an optional embodiment of the present utility model, based on Figure 1-Figure 16 As for the thin film surface acoustic wave resonator shown, the thin film surface acoustic wave resonator also includes:

[0109] The passivation layer is located on the side of the interdigital electrode 13 away from the substrate 11. The orthographic projection of the passivation layer on the substrate 11 at least completely covers the orthographic projection of the interdigital electrode 13 on the substrate 11. The passivation layer mainly provides a protective function. The material of the passivation layer can be SiO2 material, Si3N4 material or AlN material.

[0110] It should be noted that the improved solution in the technical solution of the utility model is applicable to any of the above-mentioned thin film surface acoustic wave resonators.

[0111] Based on the above embodiments of the utility model, the effect of suppressing clutter and improving the Q value of the technical solution is demonstrated based on simulation results.

[0112] refer to Fig.17 , Fig.17 A schematic diagram of the effect of clutter suppression in a Y curve provided by an embodiment of the utility model, referring to Fig.18 , Fig.18 It is a schematic diagram of the effect of improving the Q value in a Y curve provided in an embodiment of the utility model, wherein curve 1 represents the curve of the comparative example, and curve 2 represents the curve of the embodiment.

[0113] The comparative example is as follows: a 750nm LT layer (piezoelectric film layer 12) and a 625nm SiO2 layer (temperature compensation layer 16) are provided.

[0114] The embodiment is as follows: a 750nm LT layer (piezoelectric film layer 12), a 315nm SiO2 layer, a 10nm Si3N4 layer and a 300nm SiO2 layer are provided, wherein the 315nm SiO2 layer and the 300nm SiO2 layer are the temperature compensation layer 16, and a 10nm intermediate layer 15 of Si3N4 material is inserted in the middle of the temperature compensation layer 16.

[0115] For LB (low band), such as Fig.17 and Fig.18 As shown, within the range of about 800-850MHz, based on curve 1 and curve 2, it can be seen that the structure corresponding to the embodiment has more significant clutter suppression effect and Q value improvement effect.

[0116] refer to Fig.19 , Fig.19 Another schematic diagram of the effect of clutter suppression in a Y curve provided by an embodiment of the utility model, referring to Fig. 20 , Fig. 20 It is a schematic diagram of the effect of improving the Q value in another Y curve provided in an embodiment of the utility model, wherein curve 3 represents the curve of the comparative example, and curve 4 represents the curve of the embodiment.

[0117] The comparative example is as follows: a 600nm LT layer (piezoelectric film layer 12) and a 500nm SiO2 layer (temperature compensation layer 16) are provided.

[0118] The embodiment is as follows: a 600nm LT layer (piezoelectric film layer 12), a 250nm SiO2 layer, a 10nm Si3N4 layer and a 240nm SiO2 layer are provided, wherein the 250nm SiO2 layer and the 240nm SiO2 layer are the temperature compensation layer 16, and a 10nm intermediate layer 15 of Si3N4 material is inserted in the middle of the temperature compensation layer 16.

[0119] For MB (mid-band), such as Fig.19 and Fig. 20 As shown, within the range of about 1.9-2.02 GHz, based on curve 3 and curve 4, it can be seen that the structure corresponding to the embodiment has more significant clutter suppression effect and Q value improvement effect.

[0120] refer to Fig.21 , Fig.21 A schematic diagram of the effect of clutter suppression in another Y curve provided by the embodiment of the utility model, referring to Fig. 22 , Fig. 22 A schematic diagram of the effect of improving the Q value in another Y curve provided in an embodiment of the utility model, wherein curve 5 represents the curve of the comparative example, and curve 6 represents the curve of the embodiment.

[0121] The comparative example is as follows: a 270nm LT layer (piezoelectric film layer 12) and a 300nm SiO2 layer (temperature compensation layer 16) are provided.

[0122] The embodiment is as follows: a 270nm LT layer (piezoelectric film layer 12), a 150nm SiO2 layer, a 10nm Si3N4 layer and a 140nm SiO2 layer are provided, wherein the 150nm SiO2 layer and the 140nm SiO2 layer are the temperature compensation layer 16, and a 10nm intermediate layer 15 of Si3N4 material is inserted in the middle of the temperature compensation layer 16.

[0123] For HB (mid-band), if Fig.21 and Fig. 22 As shown, within the range of about 2.47-2.62 GHz, based on curve 5 and curve 6, it can be seen that the structure corresponding to the embodiment has more significant clutter suppression effect and Q value improvement effect.

[0124] Based on the above embodiments of the present invention, a filter is provided in another embodiment of the present invention. The filter includes the thin film surface acoustic wave resonator described in the above embodiments.

[0125] The filter has the same technical effect as the thin film surface acoustic wave resonator described in the above embodiment, and will not be described in detail here.

[0126] The above is a detailed introduction to a thin film surface acoustic wave resonator and filter provided by the utility model. This article uses specific examples to illustrate the principles and implementation methods of the utility model. The description of the above embodiments is only used to help understand the method and core idea of ​​the utility model. At the same time, for general technicians in this field, according to the idea of ​​the utility model, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the utility model.

[0127] It should be noted that each embodiment in this specification is described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description.

[0128] It should also be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device that includes a series of elements is inherent to the elements, or also includes elements inherent to these processes, methods, articles or devices. In the absence of further restrictions, the elements defined by the sentence "including a..." do not exclude the presence of other identical elements in the process, method, article or device that includes the elements.

[0129] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A thin film surface acoustic wave resonator, characterized in that: The thin film surface acoustic wave resonator comprises: A substrate and a piezoelectric film layer are arranged opposite to each other in a first direction, wherein the first direction is perpendicular to a plane where the substrate is located; An interdigitated electrode located on a side of the substrate facing away from the piezoelectric film layer; At least one dielectric layer located between the substrate and the piezoelectric film layer, the at least one dielectric layer comprising N sub-dielectric layers stacked in the first direction, N ≥ 2, and N is a positive integer; The intermediate layer is located between two adjacent sub-dielectric layers, and the thickness of the intermediate layer in the first direction is less than 0.2λ, where λ is the wavelength of the sound wave propagating in the thin film surface acoustic wave resonator.

2. The thin film surface acoustic wave resonator according to claim 1, characterized in that: The intermediate layer is an intermediate layer of silicon nitride, aluminum nitride or polysilicon.

3. The thin film surface acoustic wave resonator according to claim 1, characterized in that: The at least one dielectric layer includes a temperature compensation layer.

4. The thin film surface acoustic wave resonator according to claim 1, characterized in that: The at least one dielectric layer comprises: a temperature compensation layer and a first reflective layer stacked in the first direction; The temperature compensation layer is disposed adjacent to the piezoelectric film layer, and the first reflective layer is disposed adjacent to the substrate.

5. The thin film surface acoustic wave resonator according to claim 4, characterized in that: The intermediate layer is arranged in the temperature compensation layer and / or the intermediate layer is arranged in the first reflection layer.

6. The thin film surface acoustic wave resonator according to claim 1, characterized in that: The at least one dielectric layer comprises: a temperature compensation layer, a first reflection layer, and a second reflection layer stacked in the first direction, wherein the sound propagation velocity in the first reflection layer is different from the sound propagation velocity in the second reflection layer; The temperature compensation layer is disposed adjacent to the piezoelectric film layer, and the first reflective layer is located between the temperature compensation layer and the substrate; The second reflective layer is located between the temperature compensation layer and the first reflective layer, or the second reflective layer is located between the first reflective layer and the substrate.

7. The thin film surface acoustic wave resonator according to claim 6, characterized in that: The intermediate layer is arranged in the temperature compensation layer and / or the intermediate layer is arranged in the first reflection layer and / or the intermediate layer is arranged in the second reflection layer.

8. The thin film surface acoustic wave resonator according to any one of claims 1 to 2 and 4 to 6, characterized in that: When M dielectric layers are arranged between the substrate and the piezoelectric film layer, M≥2, and M is a positive integer, the number of intermediate layers arranged in the i-th dielectric layer is different from the number of intermediate layers arranged in the j-th dielectric layer, i≤M, j≤M, and i≠j.

9. The thin film surface acoustic wave resonator according to claim 1, characterized in that: The intermediate layer is also located between any two film layers between the substrate and the piezoelectric film layer.

10. The thin film surface acoustic wave resonator according to claim 1, characterized in that: The interdigitated electrode includes a bus bar, which includes a first bus bar and a second bus bar arranged opposite to each other in a second direction, and a first electrode finger located on the first bus bar and a second electrode finger located on the second bus bar; the first bus bar and the second bus bar have the same length extension direction and both extend along a third direction, the second direction and the third direction are parallel to the plane where the substrate is located, and the second direction and the third direction intersect.

11. The thin film surface acoustic wave resonator according to claim 10, characterized in that: The interdigitated electrodes further include: A plurality of first dummy electrode fingers are located on the first bus bar, and a plurality of second dummy electrode fingers are located on the second bus bar, wherein the length extension direction of the dummy electrode fingers is parallel to the second direction.

12. The thin film surface acoustic wave resonator according to claim 1, characterized in that: The thin film surface acoustic wave resonator further comprises: A reflection grating is located at at least one end of the interdigital electrode along the propagation direction of the main acoustic mode.

13. A filter, characterized in that: The filter comprises the thin film surface acoustic wave resonator according to any one of claims 1 to 12.

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