Bulk acoustic wave resonator and assembly, filter, electronic device

Abstract

The present application relates to a bulk acoustic wave resonator, comprising: a substrate; an acoustic mirror; a bottom electrode; a piezoelectric layer; and a top electrode, wherein: the piezoelectric layer comprises a first layer and a second layer, the second layer is above the first layer in a thickness direction of the resonator; the resonator further comprises a connecting-end acoustic resistance layer provided at an electrode connecting end of the top electrode, an inner edge of the connecting-end acoustic resistance layer is inside an acoustic mirror boundary in a horizontal direction; an outer end edge of the first layer and / or the second layer is inside an outer edge of the connecting-end acoustic resistance layer in the horizontal direction. The present application also relates to a bulk acoustic wave resonator assembly, a filter and an electronic device.

Description

TECHNICAL FIELD

[0001] Embodiments of the present application relate to the field of semiconductor, and in particular, to a bulk acoustic wave resonator and an assembly thereof, a filter and an electronic device. BACKGROUND

[0002] With the development of 5G communication technology, the requirement for data transmission rate is higher and higher. Corresponding to the data transmission rate is the high utilization of frequency spectrum resources and the complication of frequency spectrum. The complication of communication protocol puts strict requirements on various performances of radio frequency system. In the radio frequency front-end module, the radio frequency filter plays a crucial role, which can filter out the out-of-band interference and noise to meet the requirements of signal-to-noise ratio of radio frequency system and communication protocol.

[0003] The traditional radio frequency filter cannot meet the requirements of high frequency communication due to the limitations of structure and performance. As a new type of MEMS device, the thin film bulk acoustic resonator (FBAR) has the advantages of small size, light weight, low insertion loss, wide frequency band and high quality factor, which well adapts to the upgrading of wireless communication system, making the FBAR technology become one of the research hotspots in the field of communication.

[0004] However, with the advent of the 5G era, there is a need to further improve the performance of FBAR in the prior art. SUMMARY

[0005] To alleviate or solve at least one aspect of the above problems in the prior art, the present application is proposed.

[0006] According to an aspect of an embodiment of the present application, a bulk acoustic wave resonator is provided, comprising:

[0007] a substrate;

[0008] an acoustic mirror;

[0009] a bottom electrode;

[0010] a piezoelectric layer; and

[0011] a top electrode,

[0012] wherein:

[0013] the piezoelectric layer comprises a first layer and a second layer, the second layer is above the first layer in the thickness direction of the resonator;

[0014] the resonator further comprises a connection-end acoustic resistance layer arranged at an electrode connection end of the top electrode, an inner edge of the connection-end acoustic resistance layer is inside the acoustic mirror boundary in the horizontal direction;

[0015] an outer edge of the first layer and / or the second layer is inside an outer edge of the connection-end acoustic resistance layer in the horizontal direction.

[0016] Embodiments of the present application also relate to a filter comprising the resonator or the assembly described above.

[0017] Embodiments of the present application also relate to an electronic device comprising the filter described above or the resonator described above or the assembly described above. BRIEF DESCRIPTION OF DRAWINGS

[0018] The following description and drawings can better help understand these and other features and advantages of various embodiments disclosed by the present application, in which like reference numerals refer to like parts throughout the several views of the drawings, in which:

[0019] Figure 1 is a top view schematic of a bulk acoustic wave resonator according to an exemplary embodiment of the present application;

[0020] Figure 2 is a cross-sectional view along the OM line in Figure 1 ;

[0021] Figure 3 exemplary shows a graph of the relationship between the width of the AW structure and the parallel resonant impedance of the bulk acoustic wave resonator in the case where the AW structure is disposed in a piezoelectric layer, in the case where the upper piezoelectric layer of the AW structure is etched, and in the case where the upper piezoelectric layer of the AW structure is not etched;

[0022] Figure 4 is a cross-sectional view of a bulk acoustic wave resonator similar to that along the OM line in Figure 1 ;

[0023] Figure 5 is a cross-sectional view of a bulk acoustic wave resonator similar to that along the OM line in Figure 1 ;

[0024] Figure 6 is a cross-sectional view of a bulk acoustic wave resonator similar to that along the OM line in Figure 1 ;

[0025] Figure 7 is a cross-sectional view of a bulk acoustic wave resonator similar to that along the OM line in Figure 1 ;

[0026] Figure 8 is a cross-sectional view of a bulk acoustic wave resonator similar to that along the OM line in Figure 1 ;

[0027] Figure 9This is a top view schematic diagram of a bulk acoustic resonator according to an exemplary embodiment of the present invention;

[0028] Figure 10 For an exemplary embodiment of the present invention, along Figure 9 A schematic diagram of the cross-section of the bulk acoustic resonator of the MOM' line in the diagram;

[0029] Figures 11A-11G An example is shown Figure 10 A cross-sectional schematic diagram of the fabrication process of a bulk acoustic resonator;

[0030] Figure 12 A bulk acoustic resonator similar to the one described in another exemplary embodiment of the invention. Figure 1 A schematic diagram of the cross-section of the OM line in the diagram;

[0031] Figure 13 A bulk acoustic resonator according to yet another exemplary embodiment of the present invention is similar to that along... Figure 1 A schematic diagram of the cross-section of the OM line in the diagram;

[0032] Figure 14 For similar to along Figure 1 A cross-sectional schematic diagram of a bulk acoustic resonator of a comparative embodiment of the MOM' line. Detailed Implementation

[0033] The technical solution of the present invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings. In this 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 thereof. These are only some embodiments of the invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0034] First, the reference numerals in the accompanying drawings of this invention are explained as follows:

[0035] 10: Substrate, with optional materials including single-crystal silicon, gallium nitride, gallium arsenide, sapphire, quartz, silicon carbide, diamond, etc.

[0036] 20: Acoustic mirror, which can be a cavity, or it can be a Bragg reflector layer or other equivalent forms. In the embodiments of the present invention, a cavity form is used.

[0037] 20A: Release channel, connecting the release port 90 to the acoustic mirror cavity.

[0038] 21: Sacrifice layer, in the case of acoustic mirror in the form of a cavity, provided in the cavity during the process of making the resonator, released in the later process to form the acoustic mirror cavity, the material of the sacrifice layer 21 can be selected from silicon dioxide, doped silicon dioxide, polysilicon, amorphous silicon, etc.

[0039] 30: Bottom electrode (including bottom electrode pin), the material can be selected from molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, or a composite of the above metals or an alloy thereof, etc.

[0040] 41: First piezoelectric layer, which can be a single crystal piezoelectric material, which can be selected from, for example, 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, or single crystal lithium tantalate, etc. It can also be a polycrystalline piezoelectric material (corresponding to single crystal, non-single crystal material), which can be selected from, for example, polycrystalline aluminum nitride, zinc oxide, PZT, etc. It can also be a rare earth element doped material containing a certain atomic ratio of the above materials, for example, doped aluminum nitride, which 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), and lutetium (Lu).

[0041] 42: Second piezoelectric layer, which can have the same or different material as the first piezoelectric layer, which can be a single crystal piezoelectric material, which can be selected from, for example, 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, or single crystal lithium tantalate, etc. It can also be a polycrystalline piezoelectric material (corresponding to single crystal, non-single crystal material), which can be selected from, for example, polycrystalline aluminum nitride, zinc oxide, PZT, etc. It can also be a rare earth element doped material containing a certain atomic ratio of the above materials, for example, doped aluminum nitride, which 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), and lutetium (Lu).

[0042] 50: Top electrode (including top electrode pin), the material can be selected from molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, or a composite of the above metals or an alloy thereof, etc.

[0043] 70: Passivation layer or process layer, which can be aluminum nitride, silicon nitride, or silicon dioxide, etc.

[0044] 80: an acoustic resistance layer, which has an acoustic resistance different from that of the first piezoelectric layer 41 and the second piezoelectric layer 42. In the illustrated embodiment of the present application, it is in the form of an air gap (i.e., AW), but it can also be in the form of a solid-state dielectric layer, such as silicon dioxide or a dopant thereof, or silicon nitride or a dopant thereof. As can be understood, the acoustic resistance of the acoustic resistance layer can be less than or greater than that of the first piezoelectric layer and the second piezoelectric layer.

[0045] 81: a sacrificial layer, which is disposed at a position corresponding to the air gap in the process of manufacturing the resonator in the case where the acoustic resistance layer is an air gap, and is released in a subsequent process to form the air gap. The sacrificial layer 81 can be selected from materials such as silicon dioxide, doped silicon dioxide, polysilicon, amorphous silicon, and the like.

[0046] 90: a release hole.

[0047] Figure 1 is a top view schematic diagram of a bulk acoustic wave resonator according to an exemplary embodiment of the present application, Figure 2 is a cross-sectional schematic diagram along the OM line in Figure 1 .

[0048] In Figures 1-2 , the bulk acoustic wave resonator includes a substrate 10, an acoustic mirror cavity 20 disposed in the substrate 10, a bottom electrode 30, a top electrode 50, and a piezoelectric layer including a first piezoelectric layer 41 and a second piezoelectric layer 42. An acoustic resistance layer 80 is disposed between the first piezoelectric layer and the second piezoelectric layer, and is in the form of an air gap. Figures 1-2 In , the passivation layer 70 is also shown.

[0049] Figures 1-2 In , the top electrode has an electrode connection end, and the acoustic resistance layer 80 is disposed above the second piezoelectric layer 42 in the effective area of the resonator.

[0050] Figure 3 Exemplary diagrams respectively show the relationship between the width of the AW structure (i.e., the acoustic resistance layer 80) and the parallel resonance impedance of the bulk acoustic wave resonator in three cases: the second piezoelectric layer 42 on the upper side of the AW structure is etched by a portion (corresponding to, for example, Figure 2 ), the first piezoelectric layer 41 on the lower side of the AW structure is etched by a portion (corresponding to, for example, Figure 7 ), and the piezoelectric layer on the upper and lower sides of the AW structure is not etched (corresponding to Figure 14 ). Figure 3 In Figure 3In the diagram, solid lines indicate that the piezoelectric layers on the top and bottom sides of the AW structure are not etched, thin dashed lines indicate that the second piezoelectric layer 42 on the top side of the AW structure is partially etched, and thick dashed lines indicate that the first piezoelectric layer 41 on the bottom side of the AW structure is partially etched. For example... Figure 3 As shown, when a portion of the second piezoelectric layer 42 on the upper side or the first piezoelectric layer 41 on the lower side of the AW structure is etched, the value of the parallel resonant impedance is significantly higher than the value of the parallel resonant impedance when the piezoelectric layers on the upper and lower sides of the AW structure are not etched. At the top electrode connection end, as... Figure 2 When the inner edge of the acoustic resist layer 80 and the end edge of the second piezoelectric layer 42 are positioned, they can be relative to... Figure 14 The structure in the middle reflects more transverse Lamb waves, so the Q value will be higher.

[0051] It can be seen that by etching the upper second piezoelectric layer 42 or the lower first piezoelectric layer 41 of the AW structure, while not etching either the first or second piezoelectric layer, the performance of the resonator can be further improved.

[0052] The above performance comparison can also be applied similarly to... Figures 4-5 The embodiment shown. It should be noted that it is also possible to etch only a portion of the first piezoelectric layer 41 (see, for example, the embodiment described later). Figures 6-8 Alternatively, etching both the first and second piezoelectric layers simultaneously can achieve the desired result. Figure 3 A similar effect to that shown.

[0053] Figure 4 For another exemplary embodiment of the invention, similar to along Figure 1 A schematic diagram of the cross-section of the bulk acoustic resonator with the OM line. Figure 5 For yet another exemplary embodiment of the invention, similar to along Figure 1 A schematic diagram of the cross-section of the bulk acoustic resonator with the OM line. Figure 4 and Figure 5 The structure shown is Figure 2 The structures shown differ in that, among the three, the outer edge of the acoustic resist layer 80 is positioned differently in the horizontal direction at the electrode connection end of the top electrode. Figure 2 In this configuration, the outer edge of the second piezoelectric layer 42 lies horizontally between the boundary of the acoustic mirror 20 and the edge of the non-electrode connection end of the bottom electrode 30. Figure 4 In the middle, the outer edge of the second piezoelectric layer 42 is located inside the boundary of the acoustic mirror 20 in the horizontal direction; in Figure 4 In the resonator, at the electrode connection end of the top electrode, within the effective region of the resonator, the upper surface of the acoustic resist layer 80 is the second piezoelectric layer 42 and the top electrode 50. Figure 5In the middle, the outer edge of the second piezoelectric layer 42 is located horizontally between the edge of the non-electrode connection end of the bottom electrode 30 and the outer edge of the acoustic resist layer 80; in Figure 5 In the middle, at the electrode connection end of the top electrode, within the effective region of the resonator, the upper surface of the acoustic resist layer 80 is the second piezoelectric layer 42.

[0054] exist Figures 1-5 In the illustrated embodiment, at the electrode connection end of the top electrode, the acoustic resist layer 80 is located between the first piezoelectric layer 41 and the second piezoelectric layer 42, and the outer edge of the second piezoelectric layer 42 is located inside the outer edge of the acoustic resist layer 80 in the horizontal direction, or only covers a portion of the acoustic resist layer 80. However, the present invention is not limited to this. In optional embodiments, when the acoustic resist layer 80 at the electrode connection end of the top electrode is located between the first piezoelectric layer 41 and the second piezoelectric layer 42, the outer edge of the first piezoelectric layer 41 may also be located inside the outer edge of the acoustic resist layer 80 in the horizontal direction, or only cover a portion of the acoustic resist layer 80.

[0055] Figure 6 For yet another exemplary embodiment of the invention, similar to along Figure 1 A schematic diagram of the cross-section of a bulk acoustic resonator with an OM line. (See diagram below.) Figure 6 As shown, at the electrode connection end of the top electrode, the acoustic resist layer 80 is located between the first piezoelectric layer 41 and the second piezoelectric layer 42. The outer edge of the first piezoelectric layer 41 is horizontally located between the edge of the non-electrode connection end of the bottom electrode 30 and the outer edge of the acoustic resist layer 80. Figure 6 In the middle, at the electrode connection end of the top electrode, in the effective region of the resonator, the lower surface of the acoustic resist layer 80 is the first piezoelectric layer 41, and on the outer side of the outer edge of the first piezoelectric layer 41, the lower surface of the acoustic resist layer 80 can also contact the upper surface of the substrate 10.

[0056] Figure 7 To provide an exemplary embodiment of the invention, similar to that along Figure 1 A schematic diagram of the cross-section of a bulk acoustic resonator with an OM line. (See diagram below.) Figure 7 As shown, at the electrode connection end of the top electrode, the acoustic resist layer 80 is located between the first piezoelectric layer 41 and the second piezoelectric layer 42. The outer edge of the first piezoelectric layer 41 is located horizontally between the boundary of the acoustic mirror 20 and the edge of the non-electrode connection end of the bottom electrode 30. Figure 7 In the middle, at the electrode connection end of the top electrode, in the effective region of the resonator, the lower surface of the acoustic resist layer 80 is the first piezoelectric layer 41, and on the outer side of the outer edge of the first piezoelectric layer 41, the lower surface of the acoustic resist layer 80 is in contact with the upper surface of the bottom electrode 30.

[0057] Figure 8 To provide an exemplary embodiment of the invention, similar to that along Figure 1A schematic diagram of the cross-section of a bulk acoustic resonator with an OM line. (See diagram below.) Figure 8 As shown, the outer edge of the first piezoelectric layer 41 is located inside the boundary of the acoustic mirror 20 in the horizontal direction. Figure 8 In the resonator, at the electrode connection end of the top electrode, within the effective region of the resonator, the lower surface of the acoustic resist layer 80 contains the first piezoelectric layer 41 and the bottom electrode 30. Outside the boundary of the acoustic mirror 20, the lower surface of the acoustic resist layer 80 can also contact the upper surface of the bottom electrode 30, or simultaneously contact both the upper surface of the bottom electrode 30 and the upper surface of the substrate 10. Figure 8 In the middle, a part of the acoustic resist layer 80 is located above the bottom electrode and covers the bottom electrode, and another part is located above the first piezoelectric layer 41 and covers the first piezoelectric layer. In the horizontal direction, the outer edge of the first piezoelectric layer is outside the inner edge of the acoustic resist layer 80.

[0058] exist Figures 6-8 In the embodiment shown, the first piezoelectric layer 41 is below the acoustic resist layer 80 and contacts the lower surface of the acoustic resist layer 80, thus covering a portion of the lower surface of the acoustic resist layer 80.

[0059] In the above embodiments, the first piezoelectric layer 41 or the second piezoelectric layer 42 only covers a portion of the acoustic resist layer 80. However, the present invention is not limited to this. It can also be made so that at the electrode connection end of the top electrode, the outer edges of the piezoelectric layers on the upper and lower sides of the acoustic resist layer 80 are both inside the outer boundary of the acoustic resist layer 80 in the horizontal direction.

[0060] Although not shown, in an exemplary embodiment of the present invention, the outer edges of the first piezoelectric layer 41 and the second piezoelectric layer 42 may both be located inside the outer boundary of the acoustic resist layer 80 in the horizontal direction.

[0061] As will be understood, in this invention, the covering, based on different embodiments, may include covering from above and / or covering from below.

[0062] As mentioned above, a portion of the piezoelectric layer can be removed by etching, so that the outer edge of the corresponding piezoelectric layer is inside the outer boundary of the acoustic resist layer 80.

[0063] In the above embodiments, the acoustic resist layer 80 is provided only at the electrode connection end of the top electrode. However, the present invention is not limited to this, and acoustic resist layers can also be provided at both the electrode connection end and the non-electrode connection end of the top electrode. Figures 9-10 Such an embodiment is shown. Figure 9 This is a top view schematic diagram of a bulk acoustic resonator according to an exemplary embodiment of the present invention. Figure 10 For an exemplary embodiment of the present invention, along Figure 9a cross-sectional view of a bulk acoustic wave resonator of the MOM' line in FIG. 8. Specifically, the acoustic resistance layer at the electrode connecting end is the connecting end acoustic resistance layer, and the acoustic resistance layer at the electrode non-connecting end is the non-connecting end acoustic resistance layer. As shown in FIG. 8, the non-connecting end acoustic resistance layer 80' is disposed between the first piezoelectric layer 41 and the second piezoelectric layer 42 at the non-electrode connecting end of the top electrode, and the inner edge of the non-connecting end acoustic resistance layer 80' is on the inner side of the acoustic mirror boundary in the horizontal direction, and the acoustic resistance of the non-connecting end acoustic resistance layer is different from the acoustic resistance of the first piezoelectric layer 41 and the second piezoelectric layer 42. Figure 10

[0064] As shown in FIG. 8, the second piezoelectric layer, the top electrode and the dielectric layer above the AW structure at the non-connecting side or the non-electrode connecting end of the resonator are etched together when etching the top electrode, so that the second piezoelectric layer 42, the top electrode 50 and the passivation layer 70 form the same etching surface (see FIG. 8). Figure 10 Figure 11G The first piezoelectric layer 41 below the AW structure is not etched at the non-active area of the resonator, and the second piezoelectric layer 42 is etched, so that at the non-connecting side of the resonator, the non-active area of the resonator has no second piezoelectric layer. In this case, the AW structure, the second piezoelectric layer, the top electrode and the dielectric layer at the non-connecting side form the same etching surface. At the connecting side or the electrode connecting end of the resonator, the second piezoelectric layer 42 above the AW structure is partially etched, i.e., a part above the AW structure is the second piezoelectric layer 42 and a part is the top electrode, and in the active area of the resonator, the part above the AW structure is the second piezoelectric layer 42.

[0065] The fabrication process of the bulk acoustic wave resonator in FIG. 8 will be described below with reference to the flowchart shown in FIG. 9. Figures 11A-11G Figure 10 The fabrication process of the bulk acoustic wave resonator in FIG. 8 will be described below with reference to the flowchart shown in FIG. 9.

[0066] First, as shown in FIG. 10, a cavity as an acoustic mirror 20 is formed on the upper surface of the substrate 10, and then a sacrificial material is disposed on the upper surface of the substrate 10, which fills the cavity. Then, the sacrificial material on the upper surface of the substrate 10 is removed by a CMP (chemical mechanical polishing) process, and the upper surface of the sacrificial material in the cavity is made flush with the upper surface of the substrate 10, thereby forming a sacrificial layer 21. Figure 11A Second, as shown in FIG. 11, an electrode material layer is deposited and patterned on the structure in FIG. 10 to form a bottom electrode 30.

[0067] Figure 11B Third, as shown in FIG. 12, a first piezoelectric layer 41 is deposited on the structure in FIG. 11, which can be an undoped piezoelectric layer, for example. Figure 11A Fourth, as shown in FIG. 13, a second piezoelectric layer 42 is deposited on the structure in FIG. 12.

[0068] Figure 11C Fifth, as shown in FIG. 14, a top electrode 50 is deposited on the structure in FIG. 13. Figure 11B Sixth, as shown in FIG. 15, a passivation layer 70 is deposited on the structure in FIG. 14.

[0069] Figure 11D ​​​​​​As shown, in Figure 11C A sacrificial material is deposited and patterned on the upper surface of the first piezoelectric layer 41 to form a sacrificial layer 81. This sacrificial layer 81 will be released later to form AW structures 80 and 80'.

[0070] Fifth, such as Figure 11E As shown, in Figure 11D A second piezoelectric layer 42 is deposited on the upper surface of the structure, which may be, for example, a doped piezoelectric layer.

[0071] Sixth, such as Figure 11F As shown, the second piezoelectric layer 42 is etched to expose the sacrificial layer 81 at the non-electrode connection end and the electrode connection end of the top electrode.

[0072] Seventh, such as Figure 11G As shown, in Figure 11F A top electrode 50 and a protective or passivation layer 70 are fabricated on the upper surface of the structure, and then sacrificial layers 21 and 81 are released to form the acoustic mirror 20 and AW structures 80 and 80', respectively. Figure 11G As shown.

[0073] In the above embodiments, the acoustic resist layer is disposed between the first piezoelectric layer and the second piezoelectric layer in the thickness direction of the resonator; however, the present invention is not limited thereto. Figures 12-13 Different embodiments are illustrated by way of example.

[0074] Figure 12 A bulk acoustic resonator similar to the one described in another exemplary embodiment of the invention. Figure 1 A schematic diagram of the cross-section of the OM line. (See diagram below.) Figure 12 As shown, at the electrode connection end of the top electrode, the acoustic resist layer 80 is located above and covers the first piezoelectric layer 41, and in the horizontal direction, the outer edge of the second piezoelectric layer 42 is located inside the inner edge of the acoustic resist layer 80 and is spaced apart.

[0075] Furthermore, in Figure 12 In the structure shown, the top electrode 50 may include a portion located in the horizontal direction between the outer edge of the second piezoelectric layer 42 and the inner edge of the acoustic resistive layer 80. Figure 12 In the middle, the top electrode 50 includes a portion that is in contact with the upper surface of the first piezoelectric layer 41.

[0076] Although Figure 12 In this embodiment, the outer edge of the second piezoelectric layer 42 and the inner edge of the acoustic resistive layer 80 are spaced apart in the horizontal direction, but the invention is not limited thereto. Although not shown, in one embodiment of the invention, the outer edge of the second piezoelectric layer 42 and the inner edge of the acoustic resistive layer 80 may be adjacent to each other in the horizontal direction.

[0077] Figure 13A cross-sectional view of the OM line in the body acoustic wave resonator according to another exemplary embodiment of the present application is similar to that along the OM line in Figure 1 Fig. 1. Figure 13 As shown in Fig. 1, at the electrode connecting end of the top electrode, the acoustic resistance layer 80 is located above and covers the bottom electrode 30, and in the horizontal direction, the outer end edge of the first piezoelectric layer 41 is inside and spaced apart from the inner edge of the acoustic resistance layer 80.

[0078] Further, in the structure shown in Fig. 1, the second piezoelectric layer 42 includes a portion in the horizontal direction between the outer end edge of the first piezoelectric layer 41 and the inner edge of the acoustic resistance layer 80. Figure 13 In Fig. 1, the second piezoelectric layer 42 includes a portion in contact with the upper surface of the bottom electrode 30. Figure 13

[0079] Although in Fig. 1, the outer end edge of the first piezoelectric layer 41 and the inner edge of the acoustic resistance layer 80 are spaced apart in the horizontal direction, the present application is not limited thereto. Although not shown, in one embodiment of the present application, the outer end edge of the first piezoelectric layer 41 and the inner edge of the acoustic resistance layer 80 can be adjacent to each other in the horizontal direction. Although not shown, the outer edge of the acoustic resistance layer 80 can also be outside the outer end edge of the bottom electrode in the horizontal direction. All the above are within the scope of protection of the present application. Figure 13 In the above-illustrated embodiment, the outer end edge of the first piezoelectric layer 41 and / or the second piezoelectric layer 42 is inside the outer edge of the acoustic resistance layer 80 at the electrode connecting end in the horizontal direction.

[0080] In the present application, the outer end surface of the etched first piezoelectric layer or the second piezoelectric layer can be a vertical surface, and the inclined surface can have an inclination angle a in the range of 10-80 degrees.

[0081] In an embodiment of the present application, the distance between the boundary of the acoustic mirror 20 and the inner edge of the connecting end acoustic resistance layer in the horizontal direction is in the range of 0.25-10 μm.

[0082] In the present application, the AW structure or the acoustic resistance layer or the air gap is provided at the non-electrode connecting end of the top electrode, and in the case where the effective area of the resonator is a polygon, it can include the case where it is provided at only one side or multiple sides of the non-electrode connecting end, and it can also include the case where it is provided at all sides of the non-electrode connecting end. In the present application, the AW structure or the acoustic resistance layer or the air gap is provided at the electrode connecting end of the top electrode, and in the case where the effective area of the resonator is a polygon, it means that the AW structure or the acoustic resistance layer or the air gap is provided at the side where the electrode connecting end of the top electrode is located. The AW structure or the acoustic resistance layer or the air gap can also be provided around the entire effective area of the resonator.

[0083]

[0084] ​​By providing the acoustic resistance layer 80 between the first piezoelectric layer 41 and the second piezoelectric layer 42, the value of the electromechanical coupling coefficient of the resonator can also be adjusted. Since the first piezoelectric layer 41 and the second piezoelectric layer 42 are prepared separately, the two piezoelectric layers can be prepared of different materials, and the electromechanical coupling coefficient of the resonator can thus be freely adjusted. For example, the first piezoelectric layer 41 is a piezoelectric layer of a certain material (e.g., a piezoelectric layer of one of aluminum nitride, zinc oxide, lead zirconate titanate, lithium niobate, quartz, potassium niobate, lithium tantalate), and the second piezoelectric layer 42 is a doped layer of the same material as the first piezoelectric layer 41 doped with at least one of the rare earth elements mentioned above. In one specific embodiment, the first piezoelectric layer 41 and the second piezoelectric layer 42 are both piezoelectric materials based on aluminum nitride, but one of the piezoelectric layers is a piezoelectric material without any doping, and the other is a piezoelectric material doped with the element scandium. In another example, the first piezoelectric layer and the second piezoelectric layer are both doped layers of the same material, but the doping concentration of the first piezoelectric layer is different from the doping concentration of the second piezoelectric layer. In one specific embodiment, the first piezoelectric layer 41 and the second piezoelectric layer 42 are both piezoelectric materials based on aluminum nitride doped with the rare earth element scandium, but the doping concentrations of the first piezoelectric layer and the second piezoelectric layer are different. In yet another example, the material of the first piezoelectric layer 41 is one of aluminum nitride, zinc oxide, lead zirconate titanate, lithium niobate, quartz, potassium niobate, lithium tantalate, and the material of the second piezoelectric layer 42 is a different material from the material of the first piezoelectric layer. In one specific embodiment, the first piezoelectric layer is aluminum nitride, and the second piezoelectric layer is zinc oxide.

[0085] When the thickness of the piezoelectric layer is constant, when the same piezoelectric material is used on both sides of the AW structure, the electromechanical coupling coefficient of the resonator is a certain value under the same conditions, regardless of the position of the AW structure in the piezoelectric layer. However, when different piezoelectric materials are used on both sides of the AW structure, the design freedom of the electromechanical coupling coefficient of the resonator can be increased. For example, the first piezoelectric layer 41 is an undoped aluminum nitride material, and the second piezoelectric layer 42 is a scandium-doped aluminum nitride material. When the thickness of the piezoelectric layer is constant, for example, the electromechanical coupling coefficient of the piezoelectric layer using only an undoped aluminum nitride piezoelectric layer is 6%, and the electromechanical coupling coefficient of the piezoelectric layer using only a doped aluminum nitride piezoelectric layer is 10%. Therefore, when the thickness of the piezoelectric layer is constant, the electromechanical coupling coefficient of the resonator can be freely changed between 6% and 10% by controlling the doping concentrations of the first piezoelectric layer 41 and the second piezoelectric layer 42. When the thicknesses of the two piezoelectric layers are determined, the electromechanical coupling coefficients of different resonators in the filter can then be fine-tuned by controlling the width of the AW structure, so this scheme can maximize the design freedom of the electromechanical coupling coefficients of the resonators in the filter.

[0086] In the present application, the electromechanical coupling coefficient of the resonator can be adjusted by selecting the materials of the first piezoelectric layer and the second piezoelectric layer, and the difference between the electromechanical coupling coefficients of the two resonators can be changed in the above-mentioned manner.

[0087] In the above embodiment, the position of the AW structure sandwiched between the first piezoelectric layer 41 and the second piezoelectric layer 42 is not fixed. In one embodiment of the present application, the distance between the lower surface of the AW structure and the lower surface of the first piezoelectric layer 41 is greater than The distance between the upper surface of the AW structure and the second piezoelectric layer 42 is also greater than The thickness of the AW structure can be in the range of

[0088] It should be noted that in the present application, each numerical range, in addition to explicitly indicating that it does not include the end point value, can also be the median value of each numerical range, which is within the protection scope of the present application.

[0089] In the present application, up and down are relative to the bottom surface of the substrate, and the side of a component close to the bottom surface is the lower side, and the side away from the bottom surface is the upper side.

[0090] In the present application, inner and outer are relative to the center of the effective area of the resonator (the overlapping area of the piezoelectric layer, the top electrode, the bottom electrode and the acoustic mirror in the thickness direction of the resonator constitutes the effective area) in the lateral direction or the radial direction, and the side or one end of a component close to the center of the effective area is the inner side or the inner end, and the side or one end of the component away from the center of the effective area is the outer side or the outer end. For a reference position, the inner side of the position means between the position and the center of the effective area in the lateral direction or the radial direction, and the outer side of the position means farther away from the center of the effective area than the position in the lateral direction or the radial direction.

[0091] As those skilled in the art can understand, the bulk acoustic wave resonator can be used to form a filter or other semiconductor device.

[0092] Based on the above, the present application proposes the following technical solutions:

[0093] 1. A bulk acoustic wave resonator, comprising:

[0094] a substrate;

[0095] an acoustic mirror;

[0096] a bottom electrode;

[0097] a piezoelectric layer; and

[0098] a top electrode,

[0099] wherein:

[0100] the piezoelectric layer includes a first layer and a second layer, the second layer being above the first layer in a thickness direction of the resonator;

[0101] the resonator further includes a connecting-end acoustic resistance layer provided at an electrode connecting end of the top electrode, an inner edge of the connecting-end acoustic resistance layer being inside an acoustic mirror boundary in a horizontal direction;

[0102] an outer edge of the first layer and / or the second layer is inside an outer edge of the connecting-end acoustic resistance layer in the horizontal direction.

[0103] 2. The resonator according to 1, wherein:

[0104] the connecting-end acoustic resistance layer is provided between the first layer and the second layer in a thickness direction of the resonator; and

[0105] the first layer and / or the second layer covers only a part of the connecting-end acoustic resistance layer.

[0106] 3. The resonator according to 2, wherein:

[0107] an outer edge of the second layer is inside an outer edge of the connecting-end acoustic resistance layer in the horizontal direction, or covers only a part of the connecting-end acoustic resistance layer.

[0108] 4. The resonator according to 3, wherein:

[0109] the outer edge of the second layer is inside a boundary of the acoustic mirror in the horizontal direction.

[0110] 5. The resonator according to 3, wherein:

[0111] the outer edge of the second layer is between the boundary of the acoustic mirror and an edge of a non-electrode connecting end of the bottom electrode in the horizontal direction.

[0112] 6. The resonator according to 3, wherein:

[0113] the outer edge of the second layer is between an edge of a non-electrode connecting end of the bottom electrode and an outer edge of the connecting-end acoustic resistance layer in the horizontal direction.

[0114] 7. The resonator according to 2, wherein:

[0115] an outer edge of the first layer is inside an outer edge of the connecting-end acoustic resistance layer in the horizontal direction, or covers only a part of the connecting-end acoustic resistance layer.

[0116] 8. The resonator according to 7, wherein:

[0117] The outer end edge of the first layer is inside the boundary of the acoustic mirror in the horizontal direction.

[0118] 9. The resonator according to 7, wherein:

[0119] The outer end edge of the first layer is between the end edge of the non-electrode-connection end of the bottom electrode and the outer edge of the connection-end acoustic resistance layer in the horizontal direction.

[0120] 10. The resonator according to 7, wherein:

[0121] The outer end edge of the first layer is between the end edge of the non-electrode-connection end of the bottom electrode and the outer edge of the connection-end acoustic resistance layer in the horizontal direction.

[0122] 11. The resonator according to any one of 2 to 10, wherein:

[0123] The outer end edge of only one of the first layer and the second layer is inside the outer edge of the connection-end acoustic resistance layer in the horizontal direction, or only one of the first layer and the second layer covers only a part of the connection-end acoustic resistance layer.

[0124] 12. The resonator according to 1, wherein:

[0125] The connection-end acoustic resistance layer is located above and covers the first layer.

[0126] The outer end edge of the second layer is inside the inner edge of the connection-end acoustic resistance layer in the horizontal direction and is spaced apart, or the outer end edge of the second layer and the inner edge of the connection-end acoustic resistance layer are adjacent to each other in the horizontal direction.

[0127] 13. The resonator according to 12, wherein:

[0128] The top electrode includes a portion that is between the outer end edge of the second layer and the inner edge of the connection-end acoustic resistance layer in the horizontal direction.

[0129] 14. The resonator according to 1, wherein:

[0130] At least a part of the connection-end acoustic resistance layer is located above and covers the bottom electrode.

[0131] The outer end edge of the first layer is inside the inner edge of the connection-end acoustic resistance layer in the horizontal direction and is spaced apart, or the outer end edge of the first layer and the inner edge of the connection-end acoustic resistance layer are adjacent to each other in the horizontal direction.

[0132] 15. The resonator according to 14, wherein:

[0133] The second layer includes a portion that is between the outer end edge of the first layer and the inner edge of the connection-end acoustic resistance layer in the horizontal direction.

[0134] 16. The resonator according to any one of claims 1 to 15, wherein:

[0135] the resonator further comprises a non-connecting-end acoustic resistance layer disposed between the first layer and the second layer at a non-electrode connecting end of the top electrode, an inner edge of the non-connecting-end acoustic resistance layer is located inside the acoustic mirror boundary in the horizontal direction, and an acoustic resistance of the non-connecting-end acoustic resistance layer is different from the acoustic resistance of the piezoelectric layer.

[0136] 17. The resonator according to any one of claims 1 to 15, wherein:

[0137] an outer end surface of the one layer is a bevel, and an angle of the bevel is in a range of 10 to 80 degrees.

[0138] 18. The resonator according to any one of claims 1 to 15, wherein:

[0139] in the horizontal direction, a distance from the boundary of the acoustic mirror to the inner edge of the connecting-end acoustic resistance layer is in a range of 0.25 to 10 μm.

[0140] 19. The resonator according to any one of claims 1 to 18, wherein:

[0141] the acoustic resistance of the connecting-end acoustic resistance layer is different from the acoustic resistance of the piezoelectric layer.

[0142] 20. The resonator according to claim 19, wherein:

[0143] one of the first layer and the second layer is a doped layer of the other layer; or

[0144] the first layer and the second layer are both doped layers of the same material, and a doping concentration of the first layer is different from a doping concentration of the second layer; or

[0145] a material of the first layer is one of aluminum nitride, zinc oxide, lead zirconate titanate, lithium niobate, quartz, potassium niobate, and lithium tantalate, and a material of the second layer is a material different from the material of the first layer among aluminum nitride, zinc oxide, lead zirconate titanate, lithium niobate, quartz, potassium niobate, and lithium tantalate.

[0146] 21. A bulk acoustic wave resonator assembly comprising:

[0147] at least two bulk acoustic wave resonators, wherein at least one of the bulk acoustic wave resonators is the resonator according to any one of claims 1 to 20.

[0148] 22. A filter comprising the bulk acoustic wave resonator according to any one of claims 1 to 20, or the bulk acoustic wave resonator assembly according to claim 21.

[0149] 23. An electronic device comprising the filter of claim 22, or the bulk acoustic resonator of any one of claims 1-20, or the bulk acoustic resonator assembly of claim 22.

[0150] The electronic device herein includes, but is not limited to, intermediate products such as radio frequency front end, filter amplification module, and terminal products such as mobile phone, WIFI, and unmanned aerial vehicle.

[0151] Although embodiments of the present application have been shown and described, it would be appreciated by those skilled in the art that changes can be made to these embodiments without departing from the principles and spirit of the application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A bulk acoustic resonator, comprising: Base; Acoustic mirror; Bottom electrode; piezoelectric layer; and Top electrode, in: The piezoelectric layer includes a first layer and a second layer, with the second layer above the first layer in the thickness direction of the resonator. The resonator also includes a connection end acoustic resist layer disposed at the electrode connection end of the top electrode, wherein the inner edge of the connection end acoustic resist layer is located inside the boundary of the acoustic mirror in the horizontal direction. The outer edges of the first and / or second layers are located inside the outer edge of the acoustic resistive layer at the connection end in the horizontal direction.

2. The resonator according to claim 1, wherein: The acoustic resistive layer at the connection end is disposed between the first layer and the second layer in the thickness direction of the resonator; and The first and / or second layers cover only a portion of the acoustic resistive layer at the connection end.

3. The resonator according to claim 2, wherein: The outer edge of the second layer is located inside the outer edge of the acoustic resistive layer at the connection end in the horizontal direction, or only covers a portion of the acoustic resistive layer at the connection end.

4. The resonator according to claim 3, wherein: The outer edge of the second layer is located inside the boundary of the acoustic mirror in the horizontal direction.

5. The resonator according to claim 3, wherein: The outer edge of the second layer is located in the horizontal direction between the boundary of the acoustic mirror and the edge of the non-electrode connection end of the bottom electrode.

6. The resonator according to claim 3, wherein: The outer edge of the second layer is located in the horizontal direction between the edge of the non-electrode connection end of the bottom electrode and the outer edge of the acoustic resist layer of the connection end.

7. The resonator according to claim 2, wherein: The outer edge of the first layer is located inside the outer edge of the acoustic resistive layer at the connection end in the horizontal direction, or only covers a portion of the acoustic resistive layer at the connection end.

8. The resonator according to claim 7, wherein: The outer edge of the first layer is located inside the boundary of the acoustic mirror in the horizontal direction.

9. The resonator according to claim 7, wherein: The outer edge of the first layer is located in the horizontal direction between the boundary of the acoustic mirror and the edge of the non-electrode connection end of the bottom electrode.

10. The resonator according to claim 7, wherein: The outer edge of the first layer is located in the horizontal direction between the edge of the non-electrode connection end of the bottom electrode and the outer edge of the acoustic resist layer of the connection end.

11. The resonator according to any one of claims 2-10, wherein: The outer edge of only one of the first and second layers is located inside the outer edge of the acoustic resistive layer at the connection end in the horizontal direction, or only one of the first and second layers covers only a part of the acoustic resistive layer at the connection end.

12. The resonator according to claim 1, wherein: The acoustic resistive layer at the connection end is located above the first layer and covers the first layer; In the horizontal direction, the outer edge of the second layer is located inside the inner edge of the acoustic resistive layer at the connection end and is spaced apart; or in the horizontal direction, the outer edge of the second layer and the inner edge of the acoustic resistive layer at the connection end are adjacent to each other.

13. The resonator according to claim 12, wherein: The top electrode includes a portion located in the horizontal direction between the outer edge of the second layer and the inner edge of the connecting acoustic resistive layer.

14. The resonator according to claim 1, wherein: At least a portion of the acoustic resistive layer at the connection end is located above and covers the bottom electrode; In the horizontal direction, the outer edge of the first layer is located inside the inner edge of the acoustic resistive layer at the connection end and is spaced apart; or in the horizontal direction, the outer edge of the first layer and the inner edge of the acoustic resistive layer at the connection end are adjacent to each other.

15. The resonator according to claim 14, wherein: The second layer includes a portion located in the horizontal direction between the outer edge of the first layer and the inner edge of the connecting end acoustic resistive layer.

16. The resonator according to any one of claims 1-10 and 12-15, wherein: The resonator also includes a non-connection end acoustic resistive layer, which is disposed between the first layer and the second layer at the non-electrode connection end of the top electrode. The inner edge of the non-connection end acoustic resistive layer is located inside the boundary of the acoustic mirror in the horizontal direction. The acoustic resistance of the non-connection end acoustic resistive layer is different from that of the piezoelectric layer.

17. The resonator according to any one of claims 1-10 and 12-15, wherein: The outer end face of the first layer is a slope, and the slope angle of the slope is in the range of 10-80 degrees.

18. The resonator according to any one of claims 1-10, 12-15, wherein: In the horizontal direction, the distance between the boundary of the acoustic mirror and the inner edge of the acoustic resist layer at the connection end is in the range of 0.25-10 μm.

19. The resonator according to any one of claims 1-10 and 12-15, wherein: The acoustic resistance of the acoustic resistive layer at the connection end is different from that of the piezoelectric layer.

20. The resonator according to claim 19, wherein: One of the first and second layers is a doped layer of the other; or Both the first and second layers are doped layers of the same material, but the doping concentration of the first layer differs from that of the second layer; or The first layer is made of one of the following materials: aluminum nitride, zinc oxide, lead zirconate titanate, lithium niobate, quartz, potassium niobate, and lithium tantalate. The second layer is made of a different material from the first layer among aluminum nitride, zinc oxide, lead zirconate titanate, lithium niobate, quartz, potassium niobate, and lithium tantalate.

21. A bulk acoustic resonator assembly, comprising: At least two bulk acoustic resonators, wherein at least one bulk acoustic resonator is a resonator according to any one of claims 1-20.

22. A filter comprising a bulk acoustic resonator according to any one of claims 1-20, or a bulk acoustic resonator assembly according to claim 21.

23. An electronic device comprising the filter of claim 22, or the bulk acoustic resonator of any one of claims 1-20, or the bulk acoustic resonator assembly of claim 22.

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