Edge structure and filter

Abstract

The present application relates to the field of bulk acoustic wave resonators, and specifically relates to an edge structure and a filter. The edge structure comprises an edge protrusion structure provided between a bottom electrode and a top electrode of the edge structure. The edge protrusion structure comprises a first protrusion layer and a second protrusion layer stacked in a direction away from a substrate. The first protrusion layer is formed of a material having a high dielectric constant, and the second protrusion layer is formed of a material having a high acoustic resistance. Accordingly, the first protrusion layer should be located on the side close to the bottom electrode, and the second protrusion layer should be located on the side close to the top electrode. In this way, due to the presence of a metal material having high acoustic impedance, a high acoustic impedance mismatch can be achieved, thereby improving Rp. Moreover, due to the presence of the first protrusion layer, the electric field intensity of a second functional region and a third functional region outside a primary resonance region can be reduced, and secondary resonance can be suppressed, enabling the curve below spurious to be smooth.

Description

Edge structure and filter TECHNICAL FIELD

[0001] The present application relates to the field of bulk acoustic wave resonators, and in particular to an edge structure and filter. BACKGROUND

[0002] The edge structure refers to the structure corresponding to the edge part. In some semiconductor devices, the edge structure usually includes an edge protruding structure. The edge protruding structure OB is usually made of a metal material similar to the material of the upper and lower electrodes. This structure can improve the parallel impedance Rp of the resonator. However, this structure will cause the electric field intensity of the edge to be high, resulting in a large spurious resonance outside the main resonance, and ultimately leading to a bulge in the spurious below impedance curve. SUMMARY

[0003] Therefore, embodiments of the present application aim to provide an edge structure and filter to solve the problem of the bulge in the spurious below impedance curve.

[0004] The present application provides an edge structure, comprising: an edge protruding structure arranged between a bottom electrode and a top electrode of the edge structure;

[0005] The edge protruding structure comprises a first protruding layer and a second protruding layer arranged in a stacking manner away from the substrate;

[0006] The material of the first protruding layer is a high dielectric constant material; and the material of the second protruding layer is a high acoustic resistance material.

[0007] In some embodiments, the material of the first protruding layer is a non-metallic material.

[0008] In some embodiments, the material of the second protruding layer is a metallic material.

[0009] In some embodiments, the edge structure comprises a substrate, a bottom electrode, a piezoelectric layer, a top electrode, and a top electrode surface protection layer arranged in a stacking manner.

[0010] The edge structure further comprises an acoustic mirror.

[0011] In some embodiments, the top electrode surface protection layer is provided with an edge recess structure.

[0012] In some embodiments, the bottom electrode comprises a first bottom electrode layer and a second bottom electrode layer arranged in a stacking manner.

[0013] The acoustic mirror is arranged between the first bottom electrode layer and the second bottom electrode layer.

[0014] In some embodiments, further comprising: a top electrode thickening layer disposed on a side of the top electrode layer away from the substrate.

[0015] In some embodiments, further comprising: a top electrode thickening layer surface protection layer disposed on a side of the top electrode thickening layer away from the substrate.

[0016] In some embodiments, the first and second protruding layers of the edge protruding structure present a stepped structure layering.

[0017] In some embodiments, the first protruding layer and the upper surface structure wrap the second protruding layer, or the second protruding layer and the lower surface structure wrap the first protruding layer.

[0018] In some embodiments, the upper surface structure is a structure in the edge structure that is in close contact with the edge protruding structure and is further away from the substrate than the edge protruding structure.

[0019] In some embodiments, the lower surface structure is a structure in the edge structure that is in close contact with the edge protruding structure and is closer to the substrate than the edge protruding structure.

[0020] In some embodiments, the edge protruding structure is disposed between the piezoelectric layer and the top electrode.

[0021] In some embodiments, the edge protruding structure is disposed between the bottom electrode and the piezoelectric layer.

[0022] In some embodiments, the piezoelectric layer comprises a first piezoelectric layer and a second piezoelectric layer disposed in a layering manner.

[0023] In some embodiments, a sound wave reflecting structure is disposed in a region corresponding to the edge between the first piezoelectric layer and the second piezoelectric layer.

[0024] In some embodiments, the sound wave reflecting structure is a cavity.

[0025] In some embodiments, the sound wave reflecting structure material is a non-metallic material.

[0026] In some embodiments, the first protruding layer

[0027] is disposed between the first piezoelectric layer and the second piezoelectric layer; and the second protruding layer is disposed between the piezoelectric layer and the top electrode.

[0028] In some embodiments, the ratio of the thickness between the first protruding layer and the second protruding layer is 0.01-100.

[0029] In some embodiments, the ratio of the thickness between the first protruding layer and the second protruding layer is 0.5-20.

[0030] The edge structure provided by the present application comprises: an edge protruding structure is arranged between the bottom electrode and the top electrode of the edge structure; the edge protruding structure comprises a first protruding layer and a second protruding layer which are arranged in a direction away from the substrate; the material of the first protruding layer is a material with high dielectric constant; and the material of the second protruding layer is a material with high acoustic impedance. In this way, the first protruding layer of the material with high dielectric constant is arranged on the side close to the bottom electrode, and the second protruding layer of the material with high acoustic impedance is arranged on the side close to the top electrode. The high acoustic impedance can be realized due to the existence of the second protruding layer of the material with high acoustic impedance, and Rp is improved. At the same time, the existence of the first protruding layer of the material with high dielectric constant can suppress the sub-resonance, so that the spurious below curve is relatively smooth. BRIEF DESCRIPTION OF DRAWINGS

[0031] The above and other objects, features and advantages of the present application will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which:

[0032] FIG. 1 is a structural schematic diagram of a conventional edge structure.

[0033] FIG. 2 is an impedance curve of the conventional edge structure.

[0034] FIG. 3 is an impedance curve of another conventional edge structure.

[0035] FIG. 4 is a structural schematic diagram of an edge structure provided by an embodiment of the present application.

[0036] FIGS. 5-11 are preparation schematic diagrams of the edge structure provided by an embodiment of the present application.

[0037] FIG. 12 is a structural schematic diagram of an edge structure provided by another embodiment of the present application.

[0038] FIG. 13 is a structural schematic diagram of an edge structure provided by another embodiment of the present application.

[0039] FIG. 14 is a structural schematic diagram of an edge structure provided by another embodiment of the present application.

[0040] FIG. 15 is a structural schematic diagram of an edge structure provided by another embodiment of the present application.

[0041] FIG. 16 is a structural schematic diagram of an edge structure provided by another embodiment of the present application.

[0042] FIG. 17 is a structural schematic diagram of an edge structure provided by another embodiment of the present application.

[0043] Fig. 18 is a structural schematic diagram of an edge structure according to another embodiment of the present application.

[0044] Reference signs: 10, substrate; 20, acoustic mirror; 30, bottom electrode layer; 31, first bottom electrode layer; 32, second bottom electrode layer; 40, piezoelectric layer; 41, first piezoelectric layer; 42, second piezoelectric layer; 50, top electrode; 51, top electrode thickening layer; 60, top electrode surface protection layer; 61, top electrode thickening layer surface protection layer; 70, edge protruding structure; 71, first protruding layer; 72, second protruding layer; 80, release hole; 90, acoustic wave reflection structure; 91, edge recessed structure; 100, photoresist. DETAILED DESCRIPTION

[0045] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0046] SUMMARY

[0047] The edge structure refers to the structure corresponding to the edge part. In some semiconductor devices, the edge structure usually includes an edge protruding structure OB, which is usually made of a metal material similar to the material of the upper and lower electrodes. As shown in Fig. 1, the edge structure is divided into three regions: a first effective region 1, also called a main resonance region, a second functional region 2 and a third functional region 3 formed around the first effective region 1. This structure can improve the parallel impedance Rp of the resonator, as shown in Fig. 2, A1 corresponds to Rp. However, this structure will cause a high electric field intensity at the edge, causing a large secondary resonance outside the main resonance, ultimately leading to a bulge in the impedance curve below spurious, as shown in Fig. 2, B1 position corresponds to the bulge below spurious. The reason for this phenomenon is that the introduction of the OB structure of the metal material is equivalent to introducing an electrode thickening parasitic resonator in the original resonator. In this case, the vibration of the particles is intensified, ultimately leading to the formation of a bulge below spurious.

[0048] If the edge bump structure is simply changed to a non-metal material, the bulge of the curve can be suppressed, as shown in point B2 of FIG. 3, but the disadvantage is that Rp is reduced, corresponding to point A2, which is half the value of the Rp point of FIG. 2. This is because the edge bump structure composed of a non-metal material (i.e., the second functional area 2 and the third functional area 3) reduces the electric field at this point and suppresses the spurious, but the acoustic impedance of the non-metal material is low, and a high acoustic impedance mismatch cannot be achieved at the edge, resulting in easy leakage of the acoustic wave to the outside of the resonator, thereby reducing Rp. Therefore, it is difficult to achieve a high Rp while ensuring that the impedance curve below the spurious does not have a bulge by using a single edge bump structure.

[0049] The present application changes the traditional OB structure to a stack of a layer of non-metal material with low acoustic impedance and a layer of metal material with high acoustic impedance. At this time, the non-metal material should be located close to the piezoelectric layer, and the metal material should be located close to the electrode (as shown in the embodiment of FIG. 4, 71 should be a non-metal, and 72 should be a metal). In this way, a high acoustic impedance mismatch can be achieved due to the presence of the metal material with high acoustic impedance, thereby improving Rp. At the same time, the electric field intensity in the second functional area and the third functional area outside the main resonance area can be reduced due to the presence of the non-metal material, thereby suppressing the spurious, and the curve below the spurious is relatively smooth.

[0050] After introducing the basic principles of the present application, various non-limiting embodiments of the present application will be specifically introduced with reference to the accompanying drawings.

[0051] Exemplary edge structure

[0052] Referring to FIG. 4, the present application provides an edge structure, which comprises: an edge bump structure 70 arranged between the bottom electrode and the top electrode 50 of the edge structure; the edge bump structure 70 comprises a first bump layer 71 and a second bump layer 72 arranged in a stack in a direction away from the substrate 10; wherein the material of the first bump layer 71 is a material with high dielectric constant; and wherein the material of the second bump layer 72 is a material with high acoustic resistance.

[0053] Specifically, the material of the first bump layer 71 can be a non-metal material. The material of the second bump layer 72 can be a metal material.

[0054] In this way, the non-metal material should be located close to the bottom electrode (close to the piezoelectric layer 40 in FIG. 4), and the metal material should be located close to the top electrode 50. In this way, a high acoustic impedance mismatch can be achieved due to the presence of the metal material with high acoustic impedance, thereby improving Rp. At the same time, the electric field intensity in the second functional area and the third functional area outside the main resonance area can be reduced due to the presence of the non-metal material, thereby suppressing the spurious, and the curve below the spurious is relatively smooth.

[0055] In some embodiments, the edge structure includes a substrate 10, a bottom electrode, a piezoelectric layer 40, a top electrode 50, a top electrode surface protection layer 60 arranged in a stack; and the edge structure further includes an acoustic mirror 20.

[0056] Further, the top electrode surface protection layer 60 is provided with an edge recess structure.

[0057] Referring to FIGS. 5 to 11, the processing steps corresponding to the scheme provided by the present application are shown as follows:

[0058] First, referring to FIG. 5, the acoustic mirror 20 filling structure of the FBAR is prepared on the preset substrate 10.

[0059] Specifically, the acoustic mirror 20 filling structure of the FBAR (thin film bulk acoustic resonator) is a key part in the design of the resonator. The acoustic mirror 20 is usually used to reflect acoustic waves to enhance the resonance characteristics of the resonator. The following is the relevant information about the acoustic mirror 20 filling structure:

[0060] Acoustic mirror 20: can be a cavity, or can adopt Bragg reflection layer and other equivalent forms. The main function of the acoustic mirror 20 is to reflect acoustic waves to enhance the resonance frequency of the resonator.

[0061] Substrate 10: is the basis for building the acoustic mirror 20, and the optional materials include single crystal silicon, gallium nitride, gallium arsenide, sapphire, quartz, silicon carbide, diamond, etc.

[0062] The design of the acoustic mirror 20 needs to consider its ability to reflect acoustic waves, which is usually achieved by selecting appropriate materials and structure design. In the actual preparation process, the selection of materials, layer thickness, etching depth and other parameters need to be accurately controlled to ensure that the acoustic mirror 20 filling structure can meet the expected performance requirements.

[0063] Referring to FIG. 6, a bottom electrode is prepared and a piezoelectric layer 40 is deposited;

[0064] The bottom electrode is usually composed of metal materials such as molybdenum, gold or other conductive materials. The piezoelectric layer 40 is deposited on the bottom electrode, and the piezoelectric layer 40 is the core part of the FBAR, which can convert electrical signals into mechanical vibrations.

[0065] Referring to FIG. 7, an edge protrusion structure 70 is prepared, which is composed of a first protrusion layer 71 composed of a non-metal material with low acoustic impedance and a second protrusion layer 72 composed of a metal material with high acoustic impedance.

[0066] Specifically, a first bump layer 71 is prepared, which is made of a non-metal material with a low acoustic impedance, such as SiO2, PSG, AlN, SiN, etc. Then a second bump layer 72 is prepared, which is made of a metal material with a high acoustic impedance, such as molybdenum, gold or other high acoustic impedance metals. The first bump layer 71 and the second bump layer 72 are stacked to form the edge bump structure 70, which helps to increase the parallel impedance Rp of the resonator and reduce the secondary resonance.

[0067] Referring to FIG. 8, the top electrode 50 and the protective layer are prepared, and the top electrode 50 structure is etched.

[0068] That is, the top electrode 50 is prepared on the edge bump structure 70, and the top electrode 50 is usually also made of a metal material, which can be the same as or different from the bottom electrode material. The protective layer is prepared to protect the top electrode 50 from subsequent process steps.

[0069] Referring to FIG. 9, the release holes 80 are etched.

[0070] Specifically, the release holes 80 are etched in the acoustic mirror 20 structure, which will be used to release the sacrificial material in the acoustic mirror 20 in the subsequent steps.

[0071] Referring to FIG. 10, a photoresist pattern is made, which is covered by the photoresist 100 except for the release holes 80. The sacrificial material of the acoustic mirror 20 is released.

[0072] In practical applications, a photoresist pattern is made, which includes coating the photoresist 100 on different layers of the FBAR, and exposing and developing to form the required pattern. Except for the release holes 80, other parts are covered by the photoresist 100, which helps to protect the material in the subsequent etching step. The sacrificial material in the acoustic mirror 20 is removed by etching or other appropriate methods, which usually involves using chemical or physical methods to remove the material, thereby forming a cavity or reflective layer of the acoustic mirror 20.

[0073] Referring to FIG. 11, the photoresist 100 is removed to obtain the final resonator.

[0074] The specific way to remove all the remaining photoresist 100 can be achieved by chemical cleaning or plasma ashing, etc. After these steps are completed, the final resonator is obtained, which has an improved edge bump structure 70 and optimized acoustic performance.

[0075] In some embodiments, the top electrode surface protective layer 60 is provided with an edge recess structure 91. Specifically, referring to FIG. 12, the edge recess structure 91 can be provided between the first active area and the second functional area, and between the second functional area and the third functional area.

[0076] Edge notching structures can be used to reduce the parasitic capacitance and increase the resonant frequency of the resonator, and also to adjust the electrical and mechanical properties of the resonator, such as by changing the vibration mode of the resonator. The edge notching structures are provided on the top electrode surface protection layer 60 and can be formed by a specific photolithography and etching technique on the dielectric layer. The etching process needs to be precisely controlled to ensure that the size and shape of the notching structures meet the design requirements. The edge notching structures can reduce the parasitic effects of the resonator and improve the quality factor (Q value) of the resonator. They can also help suppress or reduce the subharmonic response of the resonator, thereby improving the passband performance of the filter.

[0077] Referring to FIG. 13, to reduce Rs (series resistance) and increase the bottom electrode thickness, the cavity is wrapped by the bottom electrode: that is, the bottom electrode includes: the first bottom electrode layer 31 and the second bottom electrode layer 32 are arranged in a stack; the acoustic mirror 20 is arranged between the first bottom electrode layer 31 and the second bottom electrode layer 32.

[0078] Referring to FIG. 14, to reduce Rs (series resistance) and increase the top electrode 50 thickness; in particular, it also includes: the top electrode thickening layer 51 arranged on the side of the top electrode 50 layer away from the substrate 10. The top electrode thickening layer 51 is in direct contact with the top electrode 50.

[0079] The top electrode thickening layer 51 is only arranged on the periphery of the first active area to form a third functional area; correspondingly, the top electrode surface protection layer 60 does not need to be arranged in the area where the top electrode thickening layer 51 is arranged. Correspondingly, in order to protect the top electrode thickening layer 51, the top electrode thickening layer surface protection layer 61 needs to be arranged on the side of the top electrode thickening layer 51 away from the substrate 10.

[0080] The top electrode thickening layer 51 can increase the mass and rigidity of the top electrode 50, thereby affecting the vibration mode and frequency characteristics of the resonator. It can also be used to adjust the electrical properties of the resonator, reduce Rs (series resistance) and parasitic impedance, and the material of the top electrode thickening layer 51 can be molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, or a composite or alloy of these metals, etc. These materials have good electrical conductivity and mechanical strength. The preparation of the top electrode thickening layer 51 usually involves an additional deposition process on the top electrode 50 layer to increase its thickness. The deposition technique can include physical vapor deposition (PVD), chemical vapor deposition (CVD), or other suitable thin film deposition techniques.

[0081] Referring to FIG. 15, the edge bump structure 70 formed by a layer of low acoustic impedance non-metallic material and a layer of high acoustic impedance metallic material can present a stepped shape, and does not necessarily have to be flush: in some embodiments, the edge bump structure 70 is a trapezoidal structure in a cross-section perpendicular to the substrate 10. The lower base of the edge bump structure 70 is close to the substrate 10. In the design of FBAR (Film Bulk Acoustic Resonator), the shape of the edge bump structure 70 has an important influence on its performance. Specifically, the first bump layer 71 and the upper surface structure wrap the second bump layer 72, or the second bump layer 72 and the lower surface structure wrap the first bump layer 71; wherein the upper surface structure is: the structure in the edge structure that is in close contact with the edge bump structure and is farther away from the substrate than the edge bump structure; the lower surface structure is: the structure in the edge structure that is in close contact with the edge bump structure and is closer to the substrate than the edge bump structure. The edge bump structure 70 can be designed to be stepped, which provides more flexibility to adjust the acoustic and electrical characteristics of the resonator. By adjusting the size and shape of the stepped or trapezoidal edge bump structure 70, the vibration mode of the resonator can be optimized, the parasitic effect can be reduced, and the quality factor (Q value) of the resonator can be improved. In some embodiments, the edge bump structure 70 can be designed to have different numbers of steps or trapezoidal sizes to adapt to different performance requirements and application scenarios.

[0082] Referring to FIG. 16, the edge bump structure 70 is disposed between the bottom electrode and the piezoelectric layer 40. Specifically, at this time, the edge bump structure 70 is located between the piezoelectric layer 40 and the lower electrode, and at this time, the metallic material is close to the lower electrode layer, and the non-metallic material is close to the piezoelectric layer 40 layer: in some embodiments, the edge bump structure 70 is disposed between the piezoelectric layer 40 and the top electrode 50.

[0083] Referring to FIG. 17, in order to further improve Rp, an edge structure is added between the piezoelectric layer 40: the piezoelectric layer 40 includes a first piezoelectric layer 41 and a second piezoelectric layer 42 arranged in layers. The area corresponding to the edge between the first piezoelectric layer 41 and the second piezoelectric layer 42 is provided with a sound wave reflection structure 90. The sound wave reflection structure 90 is a cavity. Further, the acoustic impedance of the material of the sound wave reflection structure 90 is less than or equal to the acoustic impedance of air. In some embodiments, the sound wave reflection structure 90 can correspond to the first effective area and the third functional area.

[0084] The piezoelectric layer 40 is composed of at least two layers, i.e. the first piezoelectric layer 41 and the second piezoelectric layer 42, which are the core part of the FBAR and responsible for converting electrical energy into mechanical vibration. Between the first piezoelectric layer 41 and the second piezoelectric layer 42, there is a region corresponding to the edge, and the acoustic wave reflection structure 90 is arranged in this region. This structure helps to enhance the reflection and propagation of acoustic waves inside the resonator. The acoustic wave reflection structure 90 is designed as a cavity, and this cavity structure can effectively reflect acoustic waves, thereby enhancing the resonance characteristics of the resonator. The material of the acoustic wave reflection structure 90 should have a lower acoustic impedance, less than or equal to the acoustic impedance of air, for example, it can be a non-metallic material, which helps the propagation and reflection of acoustic waves in the structure. The material with lower acoustic impedance can reduce the energy loss of acoustic waves when entering and leaving the reflection structure, thereby improving the Q value and Rp of the resonator.

[0085] In some embodiments, the first protruding layer 71 is arranged between the first piezoelectric layer 41 and the second piezoelectric layer 42; and the second protruding layer 72 is arranged between the piezoelectric layer 40 and the top electrode 50. The first protruding layer 71 is composed of a non-metallic material with lower acoustic impedance, and is arranged between the first piezoelectric layer 41 and the second piezoelectric layer 42. This arrangement helps to form a region with lower acoustic impedance between the two piezoelectric layers 40, which can help the propagation of acoustic waves between the piezoelectric layers 40, while reducing the reflection of acoustic waves between these layers. The second protruding layer 72 is composed of a metallic material with higher acoustic impedance, and is arranged between the piezoelectric layer 40 (including the first and second piezoelectric layers 42) and the top electrode 50. This configuration helps to form a region with higher acoustic impedance between the piezoelectric layer 40 and the top electrode 50, which can enhance the reflection of acoustic waves inside the resonator, thereby improving the resonance performance of the resonator.

[0086] In some embodiments, the ratio of the thickness between the first protruding layer 71 and the second protruding layer 72 is 0.01-100. Further, the ratio of the thickness between the first protruding layer 71 and the second protruding layer 72 is 0.5-20. In the design, the thickness ratio of the first protruding layer 71 and the second protruding layer 72 of the edge protruding structure 70 is a key parameter, which has a significant impact on the performance of the resonator. The thickness ratio of the first protruding layer 71 and the second protruding layer 72 affects the propagation and reflection of acoustic waves inside the resonator, and further affects the resonance frequency, quality factor (Q value) and parallel impedance (Rp) of the resonator. In some embodiments, the thickness of the first protruding layer 71 and the second protruding layer 72 can be adjusted based on actual needs.

[0087] Exemplary filter

[0088] The present application also provides a filter comprising the edge structure provided by any of the above embodiments.

[0089] Specifically, the materials of the various components in the filter are as follows:

[0090] The substrate 10 can be made of single crystal silicon, gallium nitride, gallium arsenide, sapphire, quartz, silicon carbide, diamond, etc.

[0091] The acoustic mirror 20 can be a cavity, or can be a Bragg reflector or other equivalent form.

[0092] The bottom electrode layer 30 can be made of molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, or a composite of the above metals or an alloy thereof.

[0093] The first bottom electrode layer 31 can be made of molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, or a composite of the above metals or an alloy thereof.

[0094] The second bottom electrode layer 32 can be made of molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, or a composite of the above metals or an alloy thereof.

[0095] The piezoelectric layer 40 can be made of single crystal piezoelectric material, which can be selected from single crystal aluminum nitride, single crystal gallium nitride, single crystal lithium niobate, single crystal lead zirconate titanate (PZT), single crystal potassium niobate, single crystal quartz film, single crystal lithium tantalate, etc. Alternatively, the piezoelectric layer 40 can be made of polycrystalline piezoelectric material, which can be selected from polycrystalline aluminum nitride, zinc oxide, PZT, etc. Alternatively, the piezoelectric layer 40 can be made of a rare earth element doped material containing the above-mentioned material in a certain atomic ratio, for example, doped aluminum nitride containing at least one rare earth element such as scandium (Sc), yttrium (Y), magnesium (Mg), titanium (Ti), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), etc.

[0096] The first piezoelectric layer 41 can be made of single crystal piezoelectric material, which can be selected from single crystal aluminum nitride, single crystal gallium nitride, single crystal lithium niobate, single crystal lead zirconate titanate (PZT), single crystal potassium niobate, single crystal quartz film, single crystal lithium tantalate, etc. Alternatively, the first piezoelectric layer 41 can be made of polycrystalline piezoelectric material, which can be selected from polycrystalline aluminum nitride, zinc oxide, PZT, etc. Alternatively, the first piezoelectric layer 41 can be made of a rare earth element doped material containing the above-mentioned material in a certain atomic ratio, for example, doped aluminum nitride containing at least one rare earth element such as scandium (Sc), yttrium (Y), magnesium (Mg), titanium (Ti), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), etc.

[0097] The second piezoelectric layer 42 can be a single-crystal piezoelectric material, which can be selected from single-crystal aluminum nitride, single-crystal gallium nitride, single-crystal lithium niobate, single-crystal lead zirconate titanate (PZT), single-crystal potassium niobate, single-crystal quartz thin film, single-crystal lithium tantalate, or the like, or a polycrystal piezoelectric material (non-single-crystal material), which can be selected from polycrystal aluminum nitride, zinc oxide, PZT, or the like, or a rare earth element doped material containing the above materials in a certain atomic ratio, such as doped aluminum nitride containing at least one rare earth element, such as scandium (Sc), yttrium (Y), magnesium (Mg), titanium (Ti), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu).

[0098] The top electrode 50 can be made of molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, or a composite of the above metals or an alloy thereof.

[0099] The top electrode thickening layer 51 can be made of molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, or a composite of the above metals or an alloy thereof.

[0100] The top electrode surface protection layer 60 can be made of AlN, SiN, SiO2, or Al2O3.

[0101] The top electrode thickening layer surface protection layer 61 can be made of AlN, SiN, SiO2, or Al2O3.

[0102] The edge protrusion structure 70 includes a layer of non-metallic material with a low acoustic impedance and a layer of metallic material with a high acoustic impedance.

[0103] The first protrusion layer 71 is made of a low-acoustic-impedance non-metallic material, such as SiO2, PSG, AlN, SiN, or the like.

[0104] The second protrusion layer 72 is made of a high-acoustic-impedance metallic material, such as molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, or a composite of the above metals or an alloy thereof.

[0105] The acoustic wave reflection structure 90 can be made of air or a functional material for reflecting acoustic waves, wherein the functional material has an acoustic impedance less than or equal to that of air.

[0106] The foregoing description has been presented for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of the application to the forms disclosed herein. Although various example aspects and embodiments have been discussed above, those of ordinary skill in the art will appreciate a variety of modifications, alternatives, permutations, additions, and sub-combinations, which fall within the scope of the application.

Claims

An edge structure characterized by The edge structure comprises a bottom electrode and a top electrode, and a edge protruding structure is arranged between the bottom electrode and the top electrode. The edge protruding structure comprises a first protruding layer and a second protruding layer arranged in a direction away from the substrate. The material of the first protruding layer is a high dielectric constant material. The material of the second protruding layer is a high acoustic resistance material. The edge structure according to claim 1, characterized in that The material of the first protruding layer is a non-metal material. The edge structure according to claim 1, characterized in that The material of the second protruding layer is a metal material. The edge structure according to claim 1, characterized in that The edge structure comprises a substrate, a bottom electrode, a piezoelectric layer, a top electrode, and a top electrode surface protection layer arranged in a direction away from the substrate. The edge structure further comprises an acoustic mirror. The edge structure according to claim 4, characterized in that An edge recess structure is arranged on the top electrode surface protection layer. The edge structure according to claim 4, characterized in that The bottom electrode comprises a first bottom electrode layer and a second bottom electrode layer arranged in a direction away from the substrate. The acoustic mirror is arranged between the first bottom electrode layer and the second bottom electrode layer. The edge structure according to claim 4, characterized in that Further comprising: A top electrode thickening layer arranged on a side of the top electrode layer away from the substrate. The edge structure according to claim 4, characterized in that Further comprising: A top electrode thickening layer surface protection layer arranged on a side of the top electrode thickening layer away from the substrate. The edge structure according to claim 4, characterized in that The first protruding layer and the second protruding layer of the edge protruding structure present a stepped structure. The edge structure according to claim 9, characterized in that The first protruding layer and the upper surface structure wrap the second protruding layer, or the second protruding layer and the lower surface structure wrap the first protruding layer. The upper surface structure is a structure in the edge structure that is in close contact with the edge protruding structure and is away from the substrate compared to the edge protruding structure. The lower surface structure is a structure in the edge structure that is in close contact with the edge protruding structure and is close to the substrate compared to the edge protruding structure. The edge structure according to claim 4, characterized in that The edge protruding structure is arranged between the piezoelectric layer and the top electrode. The edge structure according to claim 4, characterized in that The edge protruding structure is arranged between the bottom electrode and the piezoelectric layer. The edge structure according to claim 4, characterized in that The piezoelectric layer comprises a first piezoelectric layer and a second piezoelectric layer arranged in a direction away from the substrate. The edge structure according to claim 13, characterized in that An acoustic wave reflection structure is arranged between the first piezoelectric layer and the second piezoelectric layer corresponding to the edge. The edge structure according to claim 14, characterized in that The acoustic wave reflection structure is a cavity. The edge structure according to claim 14, characterized in that The material of the acoustic wave reflection structure is a non-metal material. The edge structure according to claim 14, characterized in that The first protruding layer is arranged between the first piezoelectric layer and the second piezoelectric layer, and the second protruding layer is arranged between the piezoelectric layer and the top electrode. The edge structure according to claim 14, characterized in that The ratio of the thickness between the first protruding layer and the second protruding layer is 0.01-100. The edge structure according to claim 14, characterized in that The ratio of the thickness between the first protruding layer and the second protruding layer is 0.5-20. A filter characterized by The edge structure as claimed in claims 1-19 is included.

Images