Bulk acoustic wave resonator, filter and electronic device having bridge insertion structure

Abstract

The present invention relates to a bulk acoustic wave resonator, comprising: a substrate; an acoustic mirror; a bottom electrode; a top electrode connected to an electrode connection portion, wherein the electrode connection portion forms a bridge portion; a piezoelectric layer, wherein: the area where the acoustic mirror, the bottom electrode, the piezoelectric layer, and the top electrode overlap in the thickness direction of the substrate is the effective area of ​​the resonator; the resonator also includes a bridge insertion structure, the bridge insertion structure includes a first insertion layer and a second insertion layer, the first insertion layer and the second insertion layer are made of different materials and at least partially overlap in a top view of the resonator; the inner end of the first insertion layer is located in the middle of the piezoelectric layer, the second insertion layer is arranged above the first insertion layer, and the inner end of the second insertion layer is connected to the first end surface of the portion of the piezoelectric layer located above the first insertion layer. The present invention also relates to filters and electronic devices.

Description

Technical Field

[0001] The embodiments of the present invention relate to the semiconductor field, and in particular to a bulk acoustic wave resonator, a filter, and an electronic device having one of the above components. Background Art

[0002] BAW filters have the advantages of low insertion loss, high rectangular coefficient, and high power capacity. Therefore, they are widely used in contemporary wireless communication systems and are important components that determine the quality of RF signals entering and leaving the communication system. The performance of BAW filters is determined by the BAW resonators that constitute them. For example, the resonant frequency of the BAW resonator determines the operating frequency of the filter, the effective electromechanical coupling coefficient determines the bandwidth of the filter, and the quality factor determines the insertion loss of the filter. When the filter structure is certain, its quality factor, especially the quality factor (or series-parallel impedance) at the series resonant frequency and parallel resonant frequency, will significantly affect the passband insertion loss. Therefore, how to improve the quality factor of the resonator is an important issue in the design of high-performance filters. The quality factor (Qs) or series impedance (Rs) of the BAW resonator at the series resonant frequency is usually determined by electrode loss and material loss, while the quality factor (Qp) or parallel impedance (Rp) of the BAW resonator at the parallel resonant frequency is usually affected by boundary acoustic wave leakage. Therefore, when the resonator material and stacking structure are determined, there is limited room for improving Qs (or Rs), but the boundary leakage of the sound wave can be effectively improved by changing the boundary structure of the resonator, thereby significantly improving the Qp (or Rp) of the resonator.

[0003] The cross-sectional structure diagram of a conventional thin film bulk acoustic wave resonator is shown in Fig.12 As shown, 100 is a substrate, 110 is an acoustic mirror, 120 is a bottom electrode, 130 is a piezoelectric layer, 140 is a top electrode, 15 is an annular protruding structure, 16 is a wing structure, h1 is the height of the gap, h2 is the thickness of the protruding structure 15, 17 is a bridge structure, and d11-d14 are various sizes.

[0004] exist Fig.12 In the example, the composite structure is located at the edge of the effective area on the upper surface of the resonator, which makes the acoustic impedance on both sides of the edge of the effective area mismatched, limiting the transmission of the lateral Lamb wave, enhancing the reflection and conversion ability of the Lamb wave, and improving Rp to a certain extent. On the connection side between the top electrode and the bottom electrode, the piezoelectric layer has poor quality due to the rough edge of the bottom electrode. The composite structure can make the resonant excitation caused by this part of the poor quality piezoelectric layer contribute less to the entire circuit, which can improve to a certain extent. And anti-static discharge ability.

[0005] However, the above structure has limited effect on improving the energy leakage problem at the edge of the effective area of ​​the resonator, and therefore the degree of improvement in Rp is also limited. Summary of the invention

[0006] The present invention is proposed to further improve the Rp value or Qp value of a BAW resonator.

[0007] According to one aspect of an embodiment of the present invention, a bulk acoustic wave resonator is proposed, in which, for example, a portion of the piezoelectric layer is etched away in the connecting edge region between the top electrode and the bottom electrode of the resonator to form an air (medium) insertion structure, which can effectively improve the Rp value of the resonator. Accordingly, the bulk acoustic wave resonator includes:

[0008] substrate;

[0009] Acoustic mirror;

[0010] bottom electrode;

[0011] a top electrode connected to the electrode connecting portion, wherein the electrode connecting portion forms a bridge portion;

[0012] Piezoelectric layer,

[0013] in:

[0014] The area where the acoustic mirror, bottom electrode, piezoelectric layer, and top electrode overlap in the thickness direction of the substrate is the effective area of ​​the resonator;

[0015] The resonator further includes a bridge insertion structure, the bridge insertion structure including a first insertion layer and a second insertion layer, the first insertion layer and the second insertion layer are made of different materials and at least partially overlap in a top view of the resonator;

[0016] The inner end of the first insertion layer is located in the middle of the piezoelectric layer, the second insertion layer is arranged above the first insertion layer, and the inner end of the second insertion layer is connected to the first end surface of the piezoelectric layer located above the first insertion layer.

[0017] Optionally, at least a portion of the lower side of the electrode connecting portion constitutes a boundary of the upper side of the second insertion layer.

[0018] Optionally, in a top view of the resonator, an inner end of the second insertion layer falls within the acoustic mirror, or at least a portion of an overlapping portion of the first insertion layer and the second insertion layer is located within the effective area.

[0019] Optionally, in a top view of the resonator, an outer end of the first insertion layer is outside an end of the bottom electrode.

[0020] Optionally, the bottom electrode is provided with a flat layer on the side where the electrode connecting portion is located, and the piezoelectric layer covers the bottom electrode and the flat layer in a flat layer manner; and the first insertion layer is a flat layer structure.

[0021] Optionally, in a top view of the resonator, the outer end of the first insertion layer is farther away from the center of the effective area in the radial direction than the outer end of the second insertion layer. Further optionally, the outer end of the first insertion layer is connected to the electrode connection portion so as to be located between the piezoelectric layer and the electrode connection portion in the thickness direction of the resonator.

[0022] Optionally, in a top view of the resonator, an outer end of the second insertion layer is farther from a center of the effective area in a radial direction than an outer end of the first insertion layer.

[0023] Optionally, in a top view of the resonator, a distance between an outer end of the first insertion layer and an end of the bottom electrode in a radial direction is in a range of 0-20 μm.

[0024] Optionally, the first insertion layer and the second insertion layer are at least partially arranged to be in contact with each other in a thickness direction of the resonator.

[0025] Optionally, in the thickness direction of the resonator, a layer of piezoelectric layer material is disposed at least partially between the first insertion layer and the second insertion layer.

[0026] Optionally, based on the inner end of the first insertion layer being disposed in the middle of the piezoelectric layer, a portion of the piezoelectric layer located above the first insertion layer and overlapping with the inner end of the first insertion layer in a top view of the resonator forms a piezoelectric layer step, and based on the piezoelectric layer step, an end of the top electrode forms a top electrode step. Further optionally, there is a gap between the upper side of the end of the piezoelectric layer step and the top side of the electrode connecting portion.

[0027] Optionally, the distance between the inner end of the first insertion layer and the inner end of the second insertion layer in the radial direction is in the range of 0-10 μm. Further optionally, the distance between the inner end of the first insertion layer and the corresponding edge of the acoustic mirror in the radial direction is in the range of 0-20 μm.

[0028] Optionally, the thickness of the first insertion layer is within the range.

[0029] Optionally, the first end surface is an inclined surface whose upper end is closer to the center of the effective area than the lower end in the top view of the resonator. Further optionally, the angle between the inclined surface and the plane where the lower end of the first end surface is located is in the range of 20-90 degrees.

[0030] Optionally, the electrode connecting portion has a protruding structure.

[0031] Optionally, the electrode connecting portion has a concave structure.

[0032] Optionally, the piezoelectric layer comprises a first piezoelectric layer and a second piezoelectric layer, the first piezoelectric layer and the second piezoelectric layer are made of different piezoelectric materials or have different doping concentrations; and the inner end of the first insertion layer is arranged between the first piezoelectric layer and the second piezoelectric layer in the thickness direction of the resonator. Further optionally, the first piezoelectric layer is aluminum nitride, and the second piezoelectric layer is doped aluminum nitride.

[0033] Optionally, the first insertion layer is a dielectric material or metal, and the second insertion layer is air or a dielectric material different from the material of the first insertion layer or a piezoelectric layer material having a doping concentration different from that of the piezoelectric layer.

[0034] Optionally, the dielectric material is one or more of the following materials: silicon dioxide, silicon nitride, silicon carbide, aluminum nitride, aluminum oxide, porous silicon, fluorinated amorphous carbon, fluoropolymer, polyparaxylene, polyarylether, hydrogen silsesquioxane, cross-linked polyphenyl polymer, bis(phenylcyclobutene), fluorinated silicon dioxide, carbon-doped oxide and diamond.

[0035] Optionally, the inner end of the first insertion layer is located between 1 / 3 and 2 / 3 of the thickness of the piezoelectric layer in the thickness direction of the piezoelectric layer.

[0036] According to yet another aspect of the embodiments of the present invention, a filter is provided, comprising the above-mentioned resonator.

[0037] According to another aspect of the embodiments of the present invention, an electronic device is provided, comprising the above-mentioned resonator or the above-mentioned filter. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The following description and accompanying drawings may better help understand these and other features and advantages of various embodiments disclosed by the present invention, in which the same reference numerals always represent the same components, wherein:

[0039] Figure 1 is a schematic top view of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention;

[0040] Figure 2 According to an exemplary embodiment of the present invention, Figure 1 A schematic partial cross-sectional view taken along the OI line in FIG.

[0041] Figure 3 According to an exemplary embodiment of the present invention, Figure 1 A schematic partial cross-sectional view taken along the OI line in FIG.

[0042] Figure 4According to an exemplary embodiment of the present invention, Figure 1 A schematic partial cross-sectional view taken along the OI line in FIG.

[0043] Figure 5 According to an exemplary embodiment of the present invention, Figure 1 A schematic partial cross-sectional view taken along the OI line in FIG.

[0044] Figure 6 According to an exemplary embodiment of the present invention, Figure 1 A schematic partial cross-sectional view taken along the OI line in FIG.

[0045] Figure 7 According to an exemplary embodiment of the present invention, Figure 1 A schematic partial cross-sectional view taken along the OI line in FIG.

[0046] Figure 8 According to an exemplary embodiment of the present invention, Figure 1 A schematic partial cross-sectional view taken along the OI line in FIG.

[0047] Fig. 9 According to an exemplary embodiment of the present invention, Figure 1 A schematic partial cross-sectional view taken along the OI line in FIG.

[0048] Fig.10 According to an exemplary embodiment of the present invention, Figure 1 A schematic partial cross-sectional view taken along the OI line in FIG.

[0049] Fig.11 According to an exemplary embodiment of the present invention, Figure 1 A schematic partial cross-sectional view taken along the OI line in FIG.

[0050] Fig.12 is a schematic cross-sectional view of a BAW resonator in the prior art. DETAILED DESCRIPTION

[0051] The technical solution of the present invention is further specifically described below by examples and in conjunction with the accompanying drawings. In the specification, the same or similar reference numerals indicate the same or similar components. The following description of the embodiments of the present invention with reference to the accompanying drawings is intended to explain the overall inventive concept of the present invention and should not be construed as a limitation of the present invention.

[0052] Figure 1 is a schematic top view of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention, Figure 2 According to an exemplary embodiment of the present invention, Figure 1Schematic partial cross-sectional view taken along line OI in FIG.

[0053] like Figure 1 As shown, the BAW resonator includes a bottom electrode, a piezoelectric layer, and a top electrode, and the letter O represents the center of the resonator.

[0054] Refer to the following Figure 2 The embodiment of the present invention illustrates the structure of the resonator. Figure 2 middle:

[0055] 10: Substrate. It is used to carry and seal the acoustic device. The material can usually be single crystal silicon, quartz, gallium arsenide or sapphire, etc.

[0056] 20: Acoustic mirror. The acoustic mirror is located on the upper surface of the substrate or embedded in the interior of the substrate. Figure 2 The acoustic mirror is formed by a cavity embedded in the substrate, but any other acoustic mirror structure such as a Bragg reflector is also suitable.

[0057] 30: Bottom electrode. The bottom electrode 120 is deposited on the upper surface of the acoustic mirror and covers the acoustic mirror. The edge of the bottom electrode 120 can be etched into a bevel, and the bevel is located outside the acoustic mirror. In addition, it can be stepped, vertical or other similar structures. The distance between the edge of the bottom electrode and the acoustic mirror is d13, and the range of d13 is 0-10um. The material can be: gold (Au), tungsten (W), molybdenum (Mo), platinum (Pt), ruthenium (Ru), iridium (Ir), titanium tungsten (TiW), aluminum (Al), titanium (Ti), osmium (Os), magnesium (Mg), gold (Au), tungsten (W), molybdenum (Mo), platinum (Pt), ruthenium (Ru), iridium (Ir), germanium (Ge), copper (Cu), aluminum (Al), chromium (Cr), arsenic doped gold and other similar metals.

[0058] 40: Piezoelectric layer. The piezoelectric layer material may be aluminum nitride (AlN), doped aluminum nitride (doped AlN) zinc oxide (ZnO), lead zirconate titanate (PZT), lithium niobate (LiNbO3), quartz (Quartz), potassium niobate (KNbO3) or lithium tantalate (LiTaO3) and the like, wherein the doped AlN contains 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) and the like.

[0059] 50: Top electrode. The material is the same as that of the bottom electrode 30. The top electrode may be covered with a passivation layer.

[0060] 60: First insertion layer. Insertion layer 60 has a first end (in the present invention, the first end is the end closer to the center of the effective area, corresponding to the inner end) and a second end (in the present invention, the second end is the end farther from the center of the effective area, corresponding to the outer end). The first end is located inside the effective area. The distance between the first end and the piezoelectric layer is d11, and the range of d11 is 0-10um. The distance between the first end and the acoustic mirror is d12, and the range of d12 is 0-20um. The second end extends out of the bottom electrode, and the distance extended is d14, and the range of d14 is 0-20um. The height of the insertion layer is h11, and the range of h11 is The material of the first insertion layer can be metal or dielectric. The material of the metal is the same as the bottom electrode 30. The horizontal center of the first insertion layer is located between 1 / 3 and 2 / 3 of the entire piezoelectric material. The dielectric material can be: silicon dioxide (SiO2), silicon nitride (Si3N4), silicon carbide (SiC), aluminum nitride (AlN), aluminum oxide (Al2O3), porous silicon, fluorinated amorphous carbon, fluoropolymer, polyparaxylene, polyarylether, hydrogen silsesquioxane, cross-linked polyphenyl polymer, bisphenylcyclobutene, fluorinated silicon dioxide, carbon-doped oxide and diamond, one or more or a combination thereof.

[0061] 70: Second insertion layer. The second insertion layer can be air or a dielectric (such as SiO2, Si3N4, AlN, doped AlN with a different doping concentration from that of the piezoelectric layer, etc.).

[0062] The overlapping area of ​​the substrate 10, the acoustic mirror 20, the bottom electrode 30, the piezoelectric layer 40, and the top electrode 50 is the effective area of ​​the resonator. Figure 2 As shown in area d15.

[0063] based on Figure 2 In the embodiment shown, on the one hand, the first insertion layer provided in the piezoelectric layer is located at the position where the stress of the piston mode of the resonator is the largest, so the impedance mismatch generated has a stronger sound wave reflection effect. On the other hand, the first insertion layer provided in the piezoelectric layer can extend to the ineffective area, thus enhancing the boundary impedance mismatch characteristics between the effective area and the ineffective area, thereby reflecting more sound waves back to the effective resonance area, which is manifested in improved Rp in terms of electrical performance. After the piezoelectric material is partially etched and filled with air, the effective area of ​​the resonator is fixed in the area shown in d15, and the effective area is also separated from the substrate at the edge of the acoustic mirror, thereby reducing the leakage of the transverse Lamb wave here, and at the same time reducing the transmission and leakage of the transverse Lamb wave in the piezoelectric material, which greatly improves the reduction of Rp due to energy leakage.

[0064] Figure 2 The selection of materials for each part in the embodiment is also applicable to other embodiments of the present invention.

[0065] Figure 3 According to an exemplary embodiment of the present invention 100 along Figure 1 A schematic partial cross-sectional view taken along the OI line in FIG. Figure 3 In the figure, 110 is a substrate, 120 is an acoustic mirror, 130 is a bottom electrode, 140 is a piezoelectric layer, 150 is a top electrode, 160 is a first insertion layer, 170 is a second insertion layer, and 180 is a protruding structure disposed at an electrode connection portion. Figure 3 The embodiment shown and Figure 1 Similarly, the difference is that the top electrode 150 has an upward protruding structure 180 near the first end of the piezoelectric layer 140. This structure is an echo reflection enhancement structure, which will cause the transverse Lamb wave propagating here to be further reflected back to the effective area, thereby increasing Rp.

[0066] Figure 4 According to an exemplary embodiment of the present invention 200 along Figure 1 A schematic partial cross-sectional view taken along the OI line in FIG. Figure 4 In the figure, 210 is a substrate, 220 is an acoustic mirror, 230 is a bottom electrode, 240 is a piezoelectric layer, 250 is a top electrode, 260 is a first insertion layer, 270 is a second insertion layer, and 280 is a descending structure disposed at an electrode connection portion. Figure 4 The embodiment shown and Figure 1 Similarly, the difference is that the top electrode 250 has a downward descending structure 280 (concave structure) near the first end of the piezoelectric layer 240. This structure is an echo reflection enhancement structure, which will cause the transverse Lamb wave propagating here to be further reflected back to the effective area, thereby increasing Rp.

[0067] Figure 5 According to an exemplary embodiment of the present invention 300 along Figure 1 A schematic partial cross-sectional view taken along the OI line in FIG. Figure 5 In the figure, 310 is a substrate, 320 is an acoustic mirror, 330 is a bottom electrode, 340 is a piezoelectric layer, 350 is a top electrode, 360 is a first insertion layer, 370 is a second insertion layer, and 380 is a first end surface of the piezoelectric layer. Figure 5 The embodiment shown and Figure 1 Similarly, the difference is that the first end of the piezoelectric layer 240 is not a vertical structure in the thickness direction, but an inclined structure, and the inclined angle is θ1, and the range of θ1 is 20-90°. Figure 5 In the embodiment shown, the first end surface is an inclined surface whose upper end is closer to the center of the effective area than the lower end in the top view of the resonator. This structure is an echo reflection enhancement structure, which will further reflect the transverse Lamb wave propagating here back to the effective area, thereby increasing Rp.

[0068] Figure 6According to an exemplary embodiment of the present invention 400 along Figure 1 A schematic partial cross-sectional view taken along the OI line in FIG. Figure 6 In the figure, 410 is a substrate, 420 is an acoustic mirror, 430 is a bottom electrode, 440 is a piezoelectric layer, 450 is a top electrode, 460 is a first insertion layer, and 470 is a second insertion layer. Figure 6 The embodiment shown and Figure 1 Similarly, the difference is that the second insertion layer 470 is filled with a dielectric, which may be SiO2, Si3N4, AlN, or doped AlN with a different doping concentration from that of the piezoelectric layer.

[0069] Figure 7 According to an exemplary embodiment of the present invention 500 along Figure 1 A schematic partial cross-sectional view taken along the OI line in FIG. Figure 7 In the figure, 510 is a substrate, 520 is an acoustic mirror, 530 is a bottom electrode, 540 is a piezoelectric layer, 550 is a top electrode, 560 is a first insertion layer, and 570 is a second insertion layer. Figure 7 The embodiment shown and Figure 1 Similarly, the difference is that the piezoelectric layer 540 is on the right side of the first end, and is not completely etched to the first insertion layer, but a portion of the piezoelectric material is retained, such as Figure 7 As shown, the height h51 is greater than the height h52. Figure 7 As shown, in the thickness direction of the resonator, a layer of piezoelectric layer material is disposed at least partially between the first insertion layer 560 and the second insertion layer 570 .

[0070] Figure 8 According to an exemplary embodiment of the present invention 600 along Figure 1 A schematic partial cross-sectional view taken along the OI line in FIG. Figure 8 In the figure, 610 is a substrate, 620 is an acoustic mirror, 630 is a bottom electrode, 640 is a piezoelectric layer, 650 is a top electrode, 660 is a first insertion layer, 670 is a second insertion layer, and 680 is a flat layer. Figure 8 The embodiment shown and Figure 1 Similarly, the difference is that the right side of the bottom electrode is filled with a flat layer 680. Figure 8 As shown, the bottom electrode 630 is provided with a flat layer 680 on the side where the electrode connection portion is located, and the piezoelectric layer covers the bottom electrode and the flat layer in a flat layer manner; and the first insertion layer 660 is a flat layer structure. Although not shown, the flat layer can also be provided in other embodiments.

[0071] Fig. 9 According to an exemplary embodiment of the present invention 800 along Figure 1 A schematic partial cross-sectional view taken along the OI line in FIG. Fig. 9In the figure, 810 is a substrate, 820 is an acoustic mirror, 830 is a bottom electrode, 840 is a piezoelectric layer, 850 is a top electrode, 860 is a first insertion layer, and 870 is a second insertion layer. Fig. 9 The embodiment shown and Figure 1 Similar, the difference is that the first insertion layer continues to extend to the right until it connects with the top electrode.

[0072] Fig.10 According to an exemplary embodiment of the present invention 900 along Figure 1 A schematic partial cross-sectional view taken along the OI line in FIG. Fig.10 In the figure, 910 is a substrate, 920 is an acoustic mirror, 930 is a bottom electrode, 940 is a piezoelectric layer, 950 is a top electrode, 960 is a first insertion layer, 970 is a second insertion layer, and 980 is a protruding structure. Fig.10 The embodiment shown and Fig. 9 Similarly, the difference is that the top electrode 950 has an upward protrusion structure 980 near the first end of the piezoelectric layer 940, and the first end 981 of the protrusion structure is located on the left side of the first end of the piezoelectric layer 940. Fig.10 As shown, there is a gap between the upper side of the end of the piezoelectric layer step and the top side of the electrode connecting portion. Fig.10 In the embodiment, the outer end of the first insertion layer 960 is connected to the electrode connection portion so as to be located between the piezoelectric layer 940 and the electrode connection portion in the thickness direction of the resonator. Fig. 9 In the embodiment, this structure avoids the influence of the roughness of the first end of the piezoelectric layer on the resonator, so that the resonance excitation caused by the poor quality piezoelectric material contributes the least to the overall circuit, which can improve the and anti-static discharge capability, increasing Rp.

[0073] Fig.11 According to an exemplary embodiment 1000 of the present invention, Figure 1 A schematic partial cross-sectional view taken along the OI line in FIG. Fig.11 In the figure, 1010 is a substrate, 1020 is an acoustic mirror, 1030 is a bottom electrode, 1040 is a first piezoelectric layer, 1041 is a second piezoelectric layer, 1050 is a top electrode, 1060 is a first insertion layer, and 1070 is a second insertion layer. Fig.11 The embodiment shown and Figure 2 The difference is that the piezoelectric layer is composed of two different piezoelectric materials, or composed of piezoelectric materials with different doping concentrations. Fig.11 In the illustrated embodiment, the first piezoelectric layer 1040 is AlN, and the second piezoelectric layer 1041 is doped AlN.

[0074] like Figure 9-10As shown, the outer end of the first insertion layer is farther from the center of the effective area in the radial direction than the outer end of the second insertion layer. Figure 2-8 as well as Fig.11 In the embodiment, the outer end of the second insertion layer is farther from the center of the effective area in the radial direction than the outer end of the first insertion layer.

[0075] like Figure 2-11 As shown, the outer end of the first insertion layer is outside the end of the bottom electrode. The present invention is not limited thereto, in the top view, the outer end of the first insertion layer may be flush with the end of the bottom electrode, or may be inside the end of the bottom electrode.

[0076] like Figure 2-6 And in 8-11, the first insertion layer and the second insertion layer are arranged at least partially in contact with each other in the thickness direction of the resonator.

[0077] like Figure 2-11 As shown, based on the inner end of the first insertion layer being arranged in the middle part of the piezoelectric layer, the part of the piezoelectric layer located above the first insertion layer and overlapping with the inner end of the first insertion layer in the top view of the resonator forms a piezoelectric layer step, and based on the piezoelectric layer step, the end of the top electrode forms a top electrode step. It should be pointed out that in the present invention, the middle part means that there is a distance between the top surface of the inner end of the first insertion layer and the top surface of the piezoelectric layer and there is a distance between the bottom surface of the inner end of the first insertion layer and the bottom surface of the piezoelectric layer. In a further embodiment, the inner end of the first insertion layer is located between 1 / 3 and 2 / 3 of the thickness of the piezoelectric layer in the thickness direction of the piezoelectric layer.

[0078] In the present invention, Figure 2 As shown, the distance d11 between the inner end of the first insertion layer and the inner end of the second insertion layer in the radial direction is in the range of 0-10 μm. The distance d12 between the inner end of the first insertion layer and the corresponding edge of the acoustic mirror in the radial direction is in the range of 0-20 μm. The thickness of the first insertion layer is The above numerical ranges may also be applicable to other embodiments of the present invention.

[0079] It should be specially pointed out that, in the present invention, for a numerical range, it can be not only the endpoint value of the given range, but also the mean value or the midpoint value of the numerical range.

[0080] Based on the above embodiments and the accompanying drawings, the present invention proposes the following technical solutions:

[0081] 1. A bulk acoustic wave resonator, comprising:

[0082] substrate;

[0083] Acoustic mirror;

[0084] bottom electrode;

[0085] a top electrode connected to the electrode connecting portion, wherein the electrode connecting portion forms a bridge portion;

[0086] Piezoelectric layer,

[0087] in:

[0088] The area where the acoustic mirror, bottom electrode, piezoelectric layer, and top electrode overlap in the thickness direction of the substrate is the effective area of ​​the resonator;

[0089] The resonator further includes a bridge insertion structure, the bridge insertion structure including a first insertion layer and a second insertion layer, the first insertion layer and the second insertion layer are made of different materials and at least partially overlap in a top view of the resonator;

[0090] The inner end of the first insertion layer is located in the middle of the piezoelectric layer, the second insertion layer is arranged above the first insertion layer, and the inner end of the second insertion layer is connected to the first end surface of the piezoelectric layer located above the first insertion layer.

[0091] It should be pointed out that the "materials are different from each other" in the statement that the first insertion layer and the second insertion layer are different from each other not only includes the difference in material selection of the two insertion layers, such as metal or dielectric, or dielectric and air, etc., but also includes that the two insertion layers may have different doping concentrations based on the same basic substance, all of which are within the protection scope of the present invention.

[0092] 2. A filter comprising the above-mentioned resonator.

[0093] 3. An electronic device, comprising the above-mentioned resonator or the above-mentioned filter. It should be noted that the electronic devices here include but are not limited to intermediate products such as RF front-ends and filter amplifier modules, as well as terminal products such as mobile phones, WIFI, and drones.

[0094] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes may be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A bulk acoustic wave resonator, comprising: substrate; Acoustic mirror; bottom electrode; a top electrode connected to the electrode connecting portion, wherein the electrode connecting portion forms a bridge portion; Piezoelectric layer, in: The area where the acoustic mirror, bottom electrode, piezoelectric layer, and top electrode overlap in the thickness direction of the substrate is the effective area of ​​the resonator; The resonator further includes a bridge insertion structure, the bridge insertion structure including a first insertion layer and a second insertion layer, the first insertion layer and the second insertion layer are made of different materials and at least partially overlap in a top view of the resonator; The inner end of the first insertion layer is located in the middle part of the piezoelectric layer, the second insertion layer is arranged above the first insertion layer, and the inner end of the second insertion layer is connected to the first end surface of the piezoelectric layer located above the first insertion layer, and the inner end of the second insertion layer covers the entire end surface of the first end surface.

2. The resonator according to claim 1, wherein: In a top view of the resonator, an inner end of the second insertion layer falls within the acoustic mirror, or at least a portion of an overlapping portion of the first insertion layer and the second insertion layer is located within the effective area.

3. The resonator of claim 1, wherein: At least a portion of the lower side of the electrode connecting portion constitutes a boundary of the upper side of the second insertion layer.

4. The resonator of claim 1, wherein: In a top view of the resonator, an outer end of the first insertion layer is outside an end of the bottom electrode.

5. The resonator of claim 4, wherein: The bottom electrode is provided with a flat layer on the side where the electrode connection portion is located, and the piezoelectric layer covers the bottom electrode and the flat layer in a flat layer manner; and The first insertion layer is a flat layer structure.

6. The resonator of claim 4, wherein: In a plan view of the resonator, an outer end of the first insertion layer is farther from a center of the effective area in a radial direction than an outer end of the second insertion layer.

7. The resonator of claim 6, wherein: An outer end of the first insertion layer is connected to the electrode connection portion so as to be located between the piezoelectric layer and the electrode connection portion in a thickness direction of the resonator.

8. The resonator of claim 4, wherein: In a plan view of the resonator, an outer end of the second insertion layer is farther from a center of the effective area in a radial direction than an outer end of the first insertion layer.

9. The resonator of claim 8, wherein: In a top view of the resonator, a distance between an outer end of the first insertion layer and an end of the bottom electrode in a radial direction is in a range of 0-20 μm.

10. The resonator of claim 1, wherein: The first insertion layer and the second insertion layer are disposed at least partially in contact with each other in a thickness direction of the resonator.

11. The resonator of claim 1 , wherein: In the thickness direction of the resonator, a layer of piezoelectric layer material is disposed at least partially between the first insertion layer and the second insertion layer.

12. The resonator of claim 1, wherein: Based on the inner end of the first insertion layer being arranged in the middle part of the piezoelectric layer, the portion of the piezoelectric layer located above the first insertion layer and overlapping with the inner end of the first insertion layer in the top view of the resonator forms a piezoelectric layer step, and based on the piezoelectric layer step, the end of the top electrode forms a top electrode step.

13. The resonator of claim 12, wherein: There is a gap between the upper side of the end of the piezoelectric layer step and the top side of the electrode connecting portion.

14. The resonator according to any one of claims 1 to 13, wherein: A distance between an inner end of the first insertion layer and an inner end of the second insertion layer in a radial direction is in a range of 0-10 μm.

15. The resonator of claim 14, wherein: The distance between the inner end of the first insertion layer and the corresponding edge of the acoustic mirror in the radial direction is in the range of 0-20 μm.

16. The resonator according to any one of claims 1 to 13, wherein: The thickness of the first insertion layer is within the range.

17. The resonator according to any one of claims 1 to 13, wherein: The first end surface is an inclined surface whose upper end is closer to the center of the effective area than the lower end in a plan view of the resonator.

18. The resonator of claim 17, wherein: The angle between the inclined surface and the plane where the lower end of the first end surface is located is in the range of 20-90 degrees.

19. The resonator according to any one of claims 1 to 13, wherein: The electrode connecting portion has a protruding structure.

20. The resonator according to any one of claims 1 to 13, wherein: The electrode connecting portion has a concave structure.

21. The resonator according to any one of claims 1 to 13, wherein: The piezoelectric layer comprises a first piezoelectric layer and a second piezoelectric layer, wherein the first piezoelectric layer and the second piezoelectric layer are made of different piezoelectric materials or have different doping concentrations; and The inner end of the first insertion layer is disposed between the piezoelectric first layer and the piezoelectric second layer in the thickness direction of the resonator.

22. The resonator of claim 21, wherein: The piezoelectric first layer is aluminum nitride, and the piezoelectric second layer is doped aluminum nitride.

23. A resonator according to any one of claims 1 to 13, wherein: The first insertion layer is a dielectric material or a metal, and the second insertion layer is air or a dielectric material different from the material of the first insertion layer or a piezoelectric layer material with a doping concentration different from that of the piezoelectric layer.

24. The resonator of claim 23, wherein: The dielectric material is one or more of the following materials: silicon dioxide, silicon nitride, silicon carbide, aluminum nitride, aluminum oxide, porous silicon, fluorinated amorphous carbon, fluoropolymer, polyparaxylene, polyarylene ether, hydrogen silsesquioxane, cross-linked polyphenyl polymer, bisphenylcyclobutene, fluorinated silicon dioxide, carbon-doped oxide and diamond.

25. The resonator of claim 1, wherein: The inner end of the first insertion layer is located between 1 / 3 and 2 / 3 of the thickness of the piezoelectric layer in the thickness direction of the piezoelectric layer.

26. A filter comprising: A bulk acoustic wave resonator according to any one of claims 1 to 25.

27. An electronic device comprising the BAW resonator according to any one of claims 1 to 25, or the filter according to claim 26.

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