Bulk acoustic wave resonator structure and manufacturing method therefor

Abstract

A bulk acoustic wave resonator structure and a manufacturing method therefor. The bulk acoustic wave resonator structure comprises: a substrate (101); a reflection structure (102), a first electrode layer (103), a piezoelectric layer (104) and a second electrode layer (105), which are stacked in sequence on the substrate (101); and a suspended protruding block (106), which is located on the piezoelectric layer (104) outside of an edge area, and which at least surrounds a first area (A1) and has a gap structure located between same and the piezoelectric layer (104) within the first area (A1) and between same and the second electrode layer (105), the top surface of the suspended protruding block (106) being higher than the top surface of the second electrode layer (105). The first area (A1) comprises part of a non-resonant region adjacent to a resonant region.

Description

Bulk acoustic wave resonant structure and manufacturing method thereof Technical Field

[0001] The embodiments of the present application relate to, but are not limited to, a bulk acoustic wave resonance structure and a manufacturing method thereof. Background Art

[0002] Film Bulk Acoustic Wave Resonator (FBAR) (also known as "bulk acoustic wave resonator") has the advantages of small size and high quality factor (Q value), and is widely used in mobile communication technology, such as filters or duplexers in mobile terminals.

[0003] On the one hand, recent research trends in BAW resonators indicate that their development has entered a large-scale commercialization phase both domestically and internationally, with theoretical and process research reaching maturity. On the other hand, the increasing number of transceiver signal formats will require more RF front-end modules to be incorporated into systems, significantly increasing the concentration and isolation requirements for filters and duplexers. In this context, only by continuously improving filter performance can the rapidly evolving demands of communications technology be met.

[0004] Summary of the Invention

[0005] An embodiment of the present application provides a bulk acoustic wave resonance structure, comprising: a substrate; a reflective structure, a first electrode layer, a piezoelectric layer, and a second electrode layer stacked in sequence on the substrate; a suspended bump located on the piezoelectric layer outside an edge region, at least surrounding the edge region and having a gap structure between the piezoelectric layer in the edge region and the second electrode layer; the top surface of the suspended bump is higher than the top surface of the second electrode layer; wherein the edge region includes a partial non-resonant region adjacent to the resonant region.

[0006] An embodiment of the present application also provides a method for manufacturing a bulk acoustic wave resonant structure, comprising: providing a substrate; forming a reflective structure, a first electrode layer, a piezoelectric layer, and a second electrode layer stacked in sequence on the substrate; forming a suspended bump on the piezoelectric layer outside the edge area, at least surrounding the edge area and having a gap structure between the piezoelectric layer in the edge area and the second electrode layer; the top surface of the suspended bump is higher than the top surface of the second electrode layer; wherein the edge area includes a partial non-resonant area adjacent to the resonant area. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG1 is a cross-sectional schematic diagram of a first bulk acoustic wave resonance structure provided in an embodiment of the present application;

[0008] FIG2 is a cross-sectional schematic diagram of a second bulk acoustic wave resonance structure provided in an embodiment of the present application;

[0009] FIG3 is a cross-sectional schematic diagram of a third bulk acoustic wave resonance structure provided in an embodiment of the present application;

[0010] FIG4 is a cross-sectional schematic diagram of a fourth bulk acoustic wave resonance structure provided in an embodiment of the present application;

[0011] FIG5 is a cross-sectional schematic diagram of a fifth bulk acoustic wave resonance structure provided in an embodiment of the present application;

[0012] FIG6 is a partial cross-sectional schematic diagram of a sixth bulk acoustic wave resonance structure provided in an embodiment of the present application;

[0013] FIG7 is a partial cross-sectional schematic diagram of a seventh bulk acoustic wave resonance structure provided in an embodiment of the present application;

[0014] FIG8 is a partial cross-sectional schematic diagram of an eighth bulk acoustic wave resonance structure provided in an embodiment of the present application;

[0015] FIG9 is a cross-sectional schematic diagram of a ninth bulk acoustic wave resonance structure provided in an embodiment of the present application;

[0016] FIG10 is a cross-sectional schematic diagram of a tenth bulk acoustic wave resonance structure provided in an embodiment of the present application;

[0017] FIG11 is a schematic diagram of a flow chart of a method for manufacturing a bulk acoustic wave resonance structure according to an embodiment of the present application;

[0018] 12 to 15 are schematic cross-sectional views of a process of manufacturing a first bulk acoustic wave resonator structure according to an embodiment of the present application;

[0019] 16 to 18 are schematic cross-sectional views of a process for manufacturing a second bulk acoustic wave resonator structure according to an embodiment of the present application;

[0020] 19 to 21 are schematic cross-sectional views of a process for manufacturing a third bulk acoustic wave resonator structure according to an embodiment of the present application;

[0021] 22A and 22B are schematic diagrams showing test results of an original structure of a bulk acoustic wave resonance structure (without a suspended bump);

[0022] 23A and 23B are schematic diagrams showing test results of a parameter comparison group of a bulk acoustic wave resonator structure (with suspended bumps);

[0023] FIG24A is a schematic diagram of the working mechanism of an original structure of a bulk acoustic wave resonance structure (without a suspended bump);

[0024] FIG24B is a schematic diagram showing the working mechanism of a suspended bump in a bulk acoustic wave resonance structure. DETAILED DESCRIPTION

[0025] The technical solution of the present application is further described in detail below with reference to the accompanying drawings and examples. Although the accompanying drawings illustrate exemplary implementation methods of the present application, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments described herein. Rather, these embodiments are provided to enable a more thorough understanding of the present application and to fully convey the scope of the present application to those skilled in the art.

[0026] The following paragraphs describe the present application in more detail by way of example with reference to the accompanying drawings. The advantages and features of the present application will become more apparent from the following description. It should be noted that the drawings are in a very simplified form and are not to exact scale, and are only used to facilitate and clearly illustrate the embodiments of the present application.

[0027] In the embodiments of the present application, the terms "first", "second", etc. are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0028] It should be noted that the technical solutions described in the embodiments of the present application can be combined arbitrarily without conflict.

[0029] The main parameters of BAW resonator include electromechanical coupling coefficient (Kt 2 ), quality factor (Q value), etc. Maintain the Kt of the resonator 2 In larger cases, the Q value of the resonator is also improved, which is crucial in filter design. The higher the global quality factor Q value (affecting the Qs value of series connection and the Qp value of parallel connection) of multiple resonators in the acoustic wave device, the less energy loss of the acoustic wave device and the better device performance. Selecting the appropriate Qs value (affecting series connection) and Qp value (affecting parallel connection) is crucial in the design of acoustic wave devices. For acoustic wave devices with multiple series resonators, a high Qs value is required, and for acoustic wave devices with multiple parallel resonators, a high Qp value is required.

[0030] It is of practical significance to set appropriate parameters of the resonator structure according to the connection mode of multiple resonator circuits in the acoustic wave device so that the global quality factor Q value (affecting the Qs value of series connection and the Qp value of parallel connection) of multiple resonators in the acoustic wave device is higher.

[0031] In the related art, when electric energy is applied to the upper and lower electrodes of the bulk acoustic wave resonator, the piezoelectric layer located in the upper and lower electrodes generates acoustic waves due to the piezoelectric effect. In addition to longitudinal waves, transverse shear waves (transverse shear waves can also be called lateral waves or shear waves) are also generated in the piezoelectric layer. The presence of transverse shear waves will affect the energy of the main longitudinal waves. Transverse shear waves will cause energy loss and deteriorate the Q value of the bulk acoustic wave resonator. Based on this, a method to improve the Q value of the bulk acoustic wave resonator is to suppress the transverse shear waves to prevent the transverse shear waves from propagating from the resonance area to the external area, thereby reducing energy leakage.

[0032] In some embodiments, providing a suspended bump at the edge of the resonance region on the piezoelectric layer of the bulk acoustic wave resonator can suppress the propagation of lateral shear waves to the external area, limit the energy within the resonance region, reduce parasitic resonance and improve the Q value; at the same time, according to the connection method of multiple resonator circuits in the acoustic wave device, the bump is set at an appropriate position in the resonator structure to further improve the global quality factor Q value of multiple resonators in the acoustic wave device (affecting the Qs value of the series and the Qp value of the parallel).

[0033] Based on this, in order to solve one or more of the above problems, according to a first aspect of various embodiments of the present application, a bulk acoustic wave resonance structure is provided.

[0034] Figure 1 is a cross-sectional schematic diagram of the first bulk acoustic wave resonance structure provided in an embodiment of the present application; Figure 2 is a cross-sectional schematic diagram of the second bulk acoustic wave resonance structure provided in an embodiment of the present application; Figure 3 is a cross-sectional schematic diagram of the third bulk acoustic wave resonance structure provided in an embodiment of the present application; Figure 4 is a cross-sectional schematic diagram of the fourth bulk acoustic wave resonance structure provided in an embodiment of the present application; and Figure 5 is a cross-sectional schematic diagram of the fifth bulk acoustic wave resonance structure provided in an embodiment of the present application.

[0035] 1 , 2 , 3 , 4 , and 5 , an embodiment of the present application provides a bulk acoustic wave resonance structure, comprising: a substrate 101; a reflective structure 102, a first electrode layer 103, a piezoelectric layer 104, and a second electrode layer 105 sequentially stacked on the substrate 101; a suspended bump 106, located on the piezoelectric layer 104 outside the edge region, at least surrounding the edge region and having a gap structure between the piezoelectric layer 104 in the edge region and the second electrode layer 105; the top surface of the suspended bump 106 is higher than the top surface of the second electrode layer 105; wherein the edge region includes a partial non-resonant region adjacent to the resonant region.

[0036] It should be noted that the suspended bump can be a continuous solid structure surrounding all or part of the edge area, and the suspended bump can continuously surround all or part of the edge area; the suspended bump can be a discontinuous structure surrounding all or part of the edge area, and the suspended bump can discontinuously surround all or part of the edge area.

[0037] It should be noted that the BAW resonant structure shown in Figures 1, 2, 3, 4, and 5 is merely an example of an embodiment of the present application and is not intended to limit the features of the BAW resonant structure in the embodiments of the present application. Other examples of BAW resonant structures in the embodiments of the present application are also shown in subsequent embodiments. The BAW resonant structures in Figures 1, 2, 3, 4, and 5 have different configurations of the suspended bumps. The BAW resonant structures in Figures 1, 2, and 3 differ from those in Figures 4 and 5 in that the BAW resonant structures in Figures 4 and 5 include a frequency modulation layer 112 located on the second electrode layer 105.

[0038] In some embodiments, the suspended bumps in the bulk acoustic wave resonant structure of Figures 4 and 5 can be replaced by the suspended bumps in the bulk acoustic wave resonant structure of Figures 1, 2 and 3 for understanding; or, the suspended bumps in the bulk acoustic wave resonant structure of Figures 1, 2 and 3 can be replaced by the suspended bumps in the bulk acoustic wave resonant structure of Figures 4 and 5 for understanding.

[0039] In practical applications, the constituent material of the substrate 101 may include silicon (Si), germanium (Ge), etc.

[0040] The first electrode layer 103 can be referred to as a lower electrode, and the second electrode layer 105 can be referred to as an upper electrode. Electrical energy can be applied to the BAW resonator via the upper and lower electrodes. The first and second electrode layers 103 and 105 can be made of the same material, specifically molybdenum (Mo), silver (Ag), aluminum (Al), ruthenium (Ru), iridium (Ir), or platinum (Pt).

[0041] The piezoelectric layer 104 can generate vibrations based on its inverse piezoelectric properties, converting the electrical signal applied to the first electrode layer 103 and the second electrode layer 105 into an acoustic signal, thereby converting electrical energy into mechanical energy. In practical applications, the piezoelectric layer 104 can be composed of materials with piezoelectric properties, such as aluminum nitride (AlN), zinc oxide (ZnO), and lithium tantalate (LiTaO3); or doped piezoelectric materials, such as scandium (Sc).

[0042] When the acoustic signal generated by the piezoelectric layer 104 propagates toward the reflective structure 102 , the acoustic signal is totally reflected at the interface between the first electrode layer 103 and the reflective structure 102 , causing the acoustic signal to be reflected back into the piezoelectric layer 104 .

[0043] In practical applications, the reflective structure 102 can be categorized into the following types: first-type cavity-type film bulk acoustic wave resonator (FBAR), second-type cavity-type FBAR, and solid-mounted resonator (SMR) resonant structure, depending on the form of the reflective structure 102. The solution provided in the present application is applicable to the above-mentioned different types of BAW resonator structures.

[0044] In some embodiments, when the BAW resonator structure includes a first type cavity-type FBAR, the reflective structure 102 includes a first electrode layer 103 protruding upwards, and a first cavity is formed between the first electrode layer 103 and the surface of the substrate 101 .

[0045] In some embodiments, when the BAW resonator structure includes a second-type cavity-type FBAR, the reflective structure 102 includes a second cavity formed between a surface depression of the substrate and the first electrode layer 103 .

[0046] In some embodiments, when the bulk acoustic wave resonant structure includes an SMR resonant structure, the reflective structure 102 includes a plurality of first dielectric layers and second dielectric layers having different acoustic impedances and alternately stacked.

[0047] It should be noted that the reflective structure 102 can be a cavity or a solid structure. When the reflective structure 102 is a cavity, it includes a first cavity or a second cavity. When the reflective structure 102 is a solid structure, it includes a plurality of alternating first and second dielectric layers. For example, here and below, the reflective structure 102 includes a first cavity formed between the upwardly protruding first electrode layer 103 and the surface of the substrate 101.

[0048] Here and below, the resonance zone (or active zone) includes the area where the reflective structure 102, the first electrode layer 103, the piezoelectric layer 104 and the second electrode layer 105 overlap along the third direction (such as the resonance zone shown in Figures 1, 2 and 3); the non-resonance zone is adjacent to the resonance zone, including the area outside the resonance zone in the bulk acoustic wave resonance structure. The resonance zone includes an effective zone and an area adjacent to the effective zone and outside the effective zone in the resonance zone. The third direction is a direction perpendicular to the surface of the substrate 101. It can be understood that the third direction can also be understood as the direction in which the first electrode layer 103, the reflective structure 102, the piezoelectric layer 104 and the second electrode layer 105 are stacked on the substrate 101.

[0049] The suspended bump 106 is located on the piezoelectric layer 104 outside the edge area, and at least surrounds the edge area and has a gap structure between the piezoelectric layer 104 in the edge area and the second electrode layer 105; the top surface of the suspended bump 106 is higher than the top surface of the second electrode layer 105; wherein the edge area includes a partial non-resonant area adjacent to the resonant area.

[0050] In some embodiments, the material of the suspended bump includes a metal material, a dielectric material, and a piezoelectric material. For example, the material of the suspended bump can be a high acoustic impedance metal material such as Mo, Ag, Al, etc., a dielectric material such as silicon oxide (SiO2) or silicon nitride (Si3N4), or a piezoelectric material such as AlN.

[0051] In some embodiments, the material of the gap structure includes an air gap and / or a low acoustic impedance material. Exemplarily, the material of the gap structure includes an air gap, or the material of the gap structure includes an air gap and a low acoustic impedance material.

[0052] In some embodiments, the gap structure comprises an air gap and a low-acoustic-impedance material. The air gap can be located between the suspended bump 106 and the piezoelectric layer 104 in the edge region, between the suspended bump 106 and the sidewall of the second electrode layer 105 in the edge region, or between the suspended bump 106 and the top surface of the second electrode layer 105 in the edge region. In other words, the air gap can be located anywhere within the edge region. Alternatively, the air gap can comprise multiple air gaps separated by the gap structure's material.

[0053] It should be noted that the gap structure including the air gap in the bulk acoustic wave resonance structure shown in Figures 1, 2, 3, 4 and 5 is only an example of an embodiment of the present application and is not used to limit the characteristics of the bulk acoustic wave resonance structure in the embodiment of the present application. Other examples of the bulk acoustic wave resonance structure in the embodiment of the present application are also shown in the following embodiments.

[0054] In some embodiments, the material of the suspended bump includes a conductive material, and the material of the gap structure includes an air gap and / or a low acoustic impedance material. For example, the material of the suspended bump can be Mo, a high acoustic impedance metal material, and the material of the gap structure includes an air gap and / or Si3N4, which can reduce lateral acoustic wave loss and thus improve the Q value.

[0055] In some embodiments, when the mass of the suspended bump is larger and the force-bearing area is smaller, the acoustic impedance is larger, the second width L1 of the bump column is smaller, and the Q value is higher. The theoretical explanation is shown in the following equations (1) to (3):

[0056] Acoustic impedance Z of bulk acoustic wave resonant structure 声 for:

[0057] Where, T represents the stress exerted by the suspended bump on the piezoelectric layer, υ 声 Indicates the speed of sound waves, F=T×A=Z 声 ×υ 声 ×A=mα (2)

[0058] Wherein, F represents the resultant force on the suspended bump, A represents the force area of ​​the suspended bump on the piezoelectric layer, m represents the mass of the suspended bump, and α represents the acceleration due to gravity;

[0059] From equations (1) and (2), we can know that the acoustic impedance Z of the BAW resonant structure is 声 for:

[0060] From formula (3), it can be seen that when the mass of the suspended bump is larger (which can be represented by the first width W1 and the first thickness H1 of the suspended bump), the force area A is smaller, and the acoustic impedance Z is 声 The larger the value, the smaller the second width L1 of the suspended bump is, the greater the impedance difference of the impedance adaptation interface during the lateral transmission of the acoustic wave is, which reduces the acoustic wave leakage, so the Q value is higher.

[0061] Figure 24A is a schematic diagram of the working mechanism of an original structure of a BAW resonator structure (without suspended bumps). Figure 24B is a schematic diagram of the working mechanism of a BAW resonator structure with suspended bumps.

[0062] 24A and 24B , the electrical impedance Z of an ideal BAW structure is explained as follows:

[0063] Among them, Kt 2 represents the electromechanical coupling coefficient of the BAW resonant structure, i represents the imaginary unit, ω represents the angular frequency, θ represents the phase difference between current and voltage, and C0 represents the static capacitance of the BAW resonant structure; the impedance is maximum at parallel resonance, and the impedance of the parallel resonance point is Z P for:

[0064] Where C0 is the static capacitance of the BAW resonant structure, and the proportional relationship between C0, the relative area S, and the distance d between electrodes is:

[0065] From the above equations (5) and (6), it can be seen that the impedance Z of the parallel resonance point is P It is directly proportional to the relative area S and inversely proportional to the distance d between electrodes.

[0066] The suspended bump transforms the overlapping portion of the inner edge of the second electrode layer into an equipotential body (zero potential region), changing the capacitance of the inner edge region and, consequently, the longitudinal impedance Z1 of that region. The suspended bump creates a cavity at the outer edge of the second electrode layer, changing the longitudinal impedance Z2 of that region. Shear waves encounter two impedance-mismatched interfaces during lateral transmission, further reducing acoustic losses caused by acoustic leakage and improving the Q value. S0 is the remaining area after excluding the zero potential region from the relative area S; this represents the longitudinal impedance Z0 of that region.

[0067] According to theoretical explanation, the first width W1 of the suspended bump can be regarded as the relative area S, and the Q value theoretically increases with the increase of the first width W1; the first distance D1 between the suspended bump and the bulk acoustic wave resonant structure and the first thickness H1 of the suspended bump can be regarded as the increased distance between the electrodes (the difference between the distance d0 between the suspended bump and the first electrode layer and the distance d between the electrodes (between the first electrode layer and the second electrode layer)), and the Q value theoretically increases with the increase of the first distance D1.

[0068] 1 and 2 , in some embodiments, the resonance region includes an effective region and a second region A2 located between the effective region and the non-resonance region; a portion of the non-resonance region adjacent to the second region A2 is the first region A1;

[0069] The suspended bump 106 surrounds the first area A1 or surrounds the first area A1 and the second area A2 , and has a gap structure between the sidewalls of the piezoelectric layer 104 in the first area A1 and the second electrode layer 105 in the second area A2 .

[0070] As shown in FIG. 1 , the first area A1 constitutes an edge area. The suspended bump 106 surrounds the first area A1 and has a gap structure between the sidewalls of the piezoelectric layer 104 and the second electrode layer 105 of the first area A1 .

[0071] As shown in FIG2 , the first area A1 and the second area A2 constitute an edge area. The suspended bump 106 surrounds the first area A1 and the second area A2 , and a gap structure is formed between the suspended bump 106 and the sidewalls of the piezoelectric layer 104 of the first area A1 and the second electrode layer 105 of the second area A2 .

[0072] In this way, a gap structure (including a cavity) surrounding the outer edge of the second electrode layer is manufactured by a suspended bump, which changes the longitudinal impedance of the gap structure area and improves the global quality factor Q value of the acoustic wave device.

[0073] 3 , in some embodiments, the resonant region includes an effective region and a second region A2 located between the effective region and the non-resonant region; the third region A3 includes a portion of the effective region adjacent to the second region; the first region A1, the second region A2, and the third region A3 constitute an edge region;

[0074] The suspended bump 106 surrounds the edge region, and a gap structure is formed between the suspended bump 106 and the piezoelectric layer 104 , the sidewall of the second electrode layer 105 , and the top surface of the second electrode layer 105 in the edge region.

[0075] In this way, a gap structure (including a cavity) is created around the outer edge of the second electrode layer by using suspended bumps, changing the longitudinal impedance of the gap structure area. The suspended bumps on the inner edge of the second electrode layer are directly introduced into the resonance region, turning the inner edge of the second electrode layer into an equipotential body, changing the capacitance of the inner edge region, and thus changing the longitudinal impedance of the inner edge region. This structure allows acoustic waves to encounter two impedance mismatch interfaces during lateral transmission, further reducing acoustic losses caused by acoustic wave leakage and improving the global quality factor (Q) of the acoustic wave device.

[0076] Referring to Figures 4 and 5, in some embodiments, the suspended bump 106 also includes an extension portion; the extension portion surrounds the fourth area A4, and has a gap structure between the piezoelectric layer 104 of the fourth area A4 and the lead 1051 of the second electrode layer 105 of the fourth area A4; the fourth area A4 includes a partial non-resonant area located outside the contact area between the suspended bump 106 and the piezoelectric layer 104.

[0077] In some embodiments, the extension portion extends along a width and a height direction of the suspended bump, and / or the extension portion extends along a top surface of the piezoelectric layer.

[0078] As shown in FIG4 , the extension portion of the suspended bump 106 surrounds the fourth area A4 and has a gap structure between the piezoelectric layer 104 of the fourth area A4 and the second electrode layer 105 of the fourth area A4. Meanwhile, the extension portion of the suspended bump 106 extends along the width and height directions of the suspended bump 106 .

[0079] As shown in Figure 5, the extended portion of the suspended bump 106 surrounds the fourth area A4, and has a gap structure between the piezoelectric layer 104 of the fourth area A4 and the second electrode layer 105 lead of the fourth area A4. At the same time, the extended portion of the suspended bump 106 extends along the top surface of the piezoelectric layer 104.

[0080] In this way, on the one hand, on the piezoelectric layer in the non-resonant area, a gap structure (including a cavity) around the outer edge of the second electrode layer is manufactured through a suspended bump at the outer edge of the second electrode layer, thereby changing the longitudinal impedance of the gap structure area; on the other hand, the suspended bump includes an extension portion, so that the greater the mass of the suspended bump, the greater the longitudinal acoustic impedance due to the mass load effect, further reducing the acoustic loss caused by acoustic wave leakage, and improving the global quality factor Q value of the acoustic wave device.

[0081] FIG6 is a partial cross-sectional schematic diagram of a sixth bulk acoustic wave resonance structure provided in an embodiment of the present application.

[0082] It should be noted that FIG6 can also be understood as a partial cross-sectional schematic diagram of any of the BAW resonator structures in FIG1, FIG2, FIG3, FIG4, and FIG5. The BAW resonator structure in FIG6 differs from the BAW resonator structures in FIG1, FIG2, and FIG3 in that the BAW resonator structure in FIG6 includes a frequency modulation layer 112 located on the second electrode layer 105. The arrangement of the suspended bumps in the BAW resonator structure in FIG6 is different from that in the BAW resonator structures in FIG4 and FIG5.

[0083] Referring to FIG6 , in some embodiments, the ratio of the thickness of the suspended bump 106 located in the third area A3 (first thickness H1) to the thickness of the second electrode layer 105 (second thickness H2) ranges from 1 to 50. It should be noted that, herein and below, when a frequency modulation layer 112 is present on the second electrode layer 105, the second thickness H2 can be understood as the sum of the thicknesses of the second electrode layer 105 and the frequency modulation layer 112. When no frequency modulation layer is present on the second electrode layer 105, the second thickness H2 can be understood as the thickness of the second electrode layer 105 (refer to FIG3 for understanding).

[0084] In some embodiments, the suspended bump 106 located in the third area A3 has a first thickness H1 and a first width W1 ; the first thickness H1 and the first width W1 are in the range of 0.5 μm to 5 μm and 1 μm to 10 μm, respectively.

[0085] In some embodiments, a first distance D1 is located between the suspended bump 106 in the third area A3 and the top surface of the resonant region structure; and a ratio of the first distance D1 to the thickness of the second electrode layer (second thickness H2) ranges from 1 to 15.

[0086] In some embodiments, there is a first distance between the suspended bump 106 located in the third area A3 and the edge of the resonance region; the first distance ranges from 0.5 μm to 1.5 μm.

[0087] FIG7 is a partial cross-sectional schematic diagram of a seventh bulk acoustic wave resonance structure provided in an embodiment of the present application.

[0088] The difference between the BAW resonant structure of FIG. 7 and the BAW resonant structure of FIG. 6 is that the width of the contact portion between the suspended bump 106 and the piezoelectric layer 104 in the BAW resonant structure of FIG. 7 is smaller than the width of the non-contact portion between the suspended bump 106 and the piezoelectric layer 104 .

[0089] 7 , in some embodiments, the width of the portion where the suspended bump 106 contacts the piezoelectric layer 104 is smaller than the width of the portion where the suspended bump 106 does not contact the piezoelectric layer 104 .

[0090] 7 and 1 , when the first area A1 constitutes an edge area, the width of the contact portion between the suspended bump 106 and the piezoelectric layer 104 has a second width L1, and the width of the non-contact portion between the suspended bump 106 and the piezoelectric layer 104 has a third distance L3, and the second width L1 is smaller than the third distance L3.

[0091] 7 and 2 , when the first area A1 and the second area A2 constitute an edge area, the width of the contact portion of the suspended bump 106 and the piezoelectric layer 104 has a second width L1, and the width of the non-contact portion of the suspended bump 106 and the piezoelectric layer 104 has a second distance L2, and the second width L1 is smaller than the second distance L2.

[0092] Referring to Figures 7 and 3 , when the first area A1, the second area A2, and the third area A3 constitute an edge area, the width of the contact portion between the suspended bump 106 and the piezoelectric layer 104 has a second width L1, and the width of the non-contact portion between the suspended bump 106 and the piezoelectric layer 104 is the sum of the second distance L2 and the first width W1. The second width L1 is smaller than the sum of the second distance L2 and the first width W1, that is, L1 < (L2 + W1).

[0093] Thus, the smaller the second width L1 of the suspended bump is, the lower the acoustic impedance Z is. 声 The larger the value, the higher the Q value. For detailed analysis, please refer to the description of the above formulas (1) to (3).

[0094] FIG8 is a partial cross-sectional schematic diagram of an eighth bulk acoustic wave resonance structure provided in an embodiment of the present application.

[0095] The difference between the BAW resonant structure of FIG8 and the BAW resonant structure of FIG6 is that the material of the contact portion between the suspended bump 106 and the piezoelectric layer 104 of the BAW resonant structure of FIG8 is different from the material of the contact portion between the suspended bump 106 and the piezoelectric layer 104 of the BAW resonant structure of FIG6 .

[0096] In some embodiments,

[0097] 6 , the suspended bump 106 includes a first bump column 1062 extending onto a portion of the piezoelectric layer 104 outside the edge region; the first bump column 1062 is made of a conductive material and / or an insulating material.

[0098] or,

[0099] Referring to Figure 8, the suspended bump includes a second bump column 1065 extending onto the pad; wherein the pad 1063 is located on a portion of the piezoelectric layer outside the edge area; the second bump column 1065 is electrically isolated from the piezoelectric layer 104 by the pad 1063; the material of the second bump column 1065 includes a conductive material; the material of the pad 1063 includes a low acoustic impedance material and / or an insulating material.

[0100] As shown in FIG6 , the suspended bump 106 includes a first bump column 1062 located outside the first area A1 and in contact with a portion of the piezoelectric layer 104, and a spacer 1061 located in the first area A1, the second area A2, and the third area A3 and spaced from a portion of the piezoelectric layer 104. The material of the first bump column 1062 and the spacer 1061 includes a conductive material and / or an insulating material. Exemplarily, the material of the first bump column is a metallic conductive material, such as Mo, Ag, Al, etc.

[0101] As shown in FIG8 , the suspended bump 106 includes a first bump column 1062 located outside the first region A1 and contacting a portion of the piezoelectric layer 104 via a spacer 1063, and a spacer 1061 located in the first region A1, the second region A2, and the third region A3 and spaced from a portion of the piezoelectric layer 104. The first bump column 1062 is electrically isolated from the piezoelectric layer 104. Exemplarily, the first bump column 1062 and the spacer 1061 are made of a conductive metal, such as Mo, Ag, or Al; the spacer is made of an insulating material, such as SiO2 or Si3N4.

[0102] In this way, through this structure, the acoustic loss caused by acoustic wave leakage can be reduced and the global quality factor Q value of the acoustic wave device can be improved.

[0103] In some embodiments, the first bump pillar 1062 or the spacer 1063 has a second width L1 ; the second width L1 ranges from 1 μm to 3 μm.

[0104] In some embodiments, a second distance L2 is formed between the first bump column 1062 or the spacer 1063 and the edge of the resonance region; and the second distance L2 ranges from 1 μm to 3 μm.

[0105] FIG9 is a schematic cross-sectional view of a ninth BAW resonant structure provided in an embodiment of the present application; FIG10 is a schematic cross-sectional view of a tenth BAW resonant structure provided in an embodiment of the present application. The BAW resonant structures of FIG9 and FIG10 differ from the BAW resonant structure of FIG3 in that the BAW resonant structures of FIG9 and FIG10 include a frequency modulation layer 112 located on the second electrode layer 105. It should be noted that FIG6 can also be understood as a schematic cross-sectional view of a portion of either BAW resonant structure of FIG9 or FIG10.

[0106] In some embodiments, the suspended bump 106 is in contact with or not in contact with the lead 1051 of the second electrode layer 105 .

[0107] Exemplarily, referring to FIG. 9 and FIG. 10 , the suspended bump 106 is in contact with the lead 1051 of the second electrode layer 105 .

[0108] 9 and 10 , in some embodiments, the suspended bump 106 includes a connecting portion 1064 extending beyond the edge region of the lead 1051 of the second electrode layer 105 ; the connecting portion 1064 contacts and is electrically connected to the lead 1051 of the second electrode layer.

[0109] Here, the suspended bump 106 is in contact and electrically connected to the lead 1051 of the second electrode layer through the connecting portion 1064 , which introduces a capacitor in the effective area. The capacitance introduced in the effective area is in phase with the electrical properties of the resonator, so no additional parasitic resonance is introduced.

[0110] In some embodiments, the resonant structure further includes a frequency modulation layer 112; the suspended bump 106 includes a connecting portion 1064 on the lead 1051 of the second electrode layer 105 extending beyond the edge region;

[0111] 9 , the frequency modulation layer 112 covers the second electrode layer 105, and the connecting portion 1064 contacts and is electrically connected to the lead 1051 of the second electrode layer; at this time, the frequency modulation layer 112 partially covers (ie, does not completely cover) or does not cover the second electrode layer lead 1051. Alternatively,

[0112] 10 , the frequency modulation layer 112 covers the second electrode layer 105 and the lead 1051 of the second electrode layer, and the connection portion 1064 penetrates the frequency modulation layer 112 and contacts and electrically connects to the lead 1051 of the second electrode layer.

[0113] 9 and 6 , in some embodiments, the suspended bump 106 in the resonance region has a first thickness H1 ; a ratio of the first thickness H1 to the sum of the thickness of the second electrode layer 105 and the thickness of the frequency modulation layer 112 (second thickness H2 ) is in the range of 0.5 to 5.

[0114] In some embodiments, the sum of the thickness of the second electrode layer 105 and the thickness of the frequency modulation layer 112 (the second thickness H2 ) is less than or equal to 1 μm.

[0115] 9 and 10 , in some embodiments, the second electrode layer 105 has inclined side surfaces.

[0116] FIG23A and FIG23B , and Tables 1 to 4 will illustrate in detail the experimental results of the original structure, the parameter control group, and the optimized parameter group of the specific BAW resonator structure.

[0117] It should be noted that the BAW resonant structure of Figures 23A and 23B can be understood with reference to Figure 8. The preferred parameters of the suspended bumps in Figures 23A and 23B, as well as in Tables 2 to 4, are different. The BAW resonant structure of Figures 22A and 22B can be understood with reference to the BAW resonant structure after the suspended bumps are removed, as shown in Figures 23A and 23B.

[0118] FIG22A shows the test results of the frequency quality factor (Q value) and impedance (Ω) of a bulk acoustic wave resonator structure (without the suspended bumps). FIG22B shows a Smith chart of the original bulk acoustic wave resonator structure (without the suspended bumps). The frequency is in megahertz (MHz).

[0119] FIG23A shows the test results of the frequency quality factor (Q value) and impedance (Ω) of a parameter comparison group of a BAW resonator structure (with suspended bumps). FIG23B shows a Smith chart of a parameter comparison group of a BAW resonator structure (with suspended bumps). The frequency is in megahertz (MHz).

[0120] Table 1 shows the comparison of Q values ​​between the original structure and the parameter control group.

[0121] Here and below, the fixed resonant area of ​​a BAW structure of the original structure and the parameter comparison group is 20000μm 2 The first width W1 of the overhanging bump of the parameter comparison group is 1 μm, the first thickness H1 is 1.5 μm, and the first distance D1 is 0.5 μm. The Qs and Qp values ​​of the original structure can be used as the control group in the following embodiments.

[0122] As shown in Figures 22A and 22B, Figures 23A and 23B, and Table 1, the Qs and Qp values ​​of the original structure are 2176 and 2045, respectively, while the Qs and Qp values ​​of the parameter control group are 2180 and 2267, respectively. It can be seen that the introduction of the suspended bump can effectively improve the Q value (Qp) of the parallel resonance point. Based on this, it is preferred that the introduction of the suspended bump in the BAW resonator structure can effectively improve the Q value.

[0123] Table 1

[0124] Table 2 compares the Q values ​​of the original structure, the parameter control group, and the first preferred parameter group (including 6 first preferred parameters), and studies the effects of the first width W1, first thickness H1, and first distance D1 of the suspended bump on the performance of a bulk acoustic wave resonant structure.

[0125] As shown in Table 2, a larger first width W1 of the suspended bump increases the Q value, with no significant loss degradation. When the distance D between the suspended bump and the resonator is small, the relationship between the first distance D1 and the Q value is not linear; the smaller the first distance D1, the greater the loss. A larger first thickness H1 of the suspended bump increases the Q value, with no significant loss degradation. Based on this, a preferred setting of a first width W1 of 5μm, a first thickness H1 of 3μm, and a first distance D1 of 2μm effectively improves the Q value.

[0126] Table 2

[0127] Table 3 compares the Q values ​​of the original structure, a control group (W1 = 5μm, H1 = 3μm, D1 = 2μm), and a second preferred parameter group (including three second preferred parameters). Here, the optimal values ​​of the parameters in the first preferred parameter group in Table 2 serve as the control group for the second preferred parameter group. Specifically, the control group for the second preferred parameter group is composed of the first width W1 = 5μm, the first thickness H1 = 3μm, and the first distance D1 = 2μm of the suspended bump. The effects of the first width W1, first thickness H1, and first distance D1 of the suspended bump on the performance of a bulk acoustic wave resonator structure are investigated.

[0128] As shown in Table 3, a larger width W1 of the suspended bump increases the Q value, with no significant degradation in loss. When the distance D between the suspended bump and the resonator is larger, a larger distance D1 increases the Q value, with no significant degradation in loss. A larger thickness H1 of the suspended bump increases the Q value, with no significant degradation in loss. Compared to the experimental results of the first preferred parameter group, the experimental results of the second preferred parameter group show a further improvement in Q value.

[0129] Table 3

[0130] Table 4 is a comparison of the Q values ​​of the original structure, the parameter control group (L1=1 μm, L2=1 μm) and the third preferred parameter group (including 6 third preferred parameters).

[0131] Here and below, the first width W1 = 5μm, the first thickness H1 = 3μm, and the first distance D1 = 2μm of the suspended bump of a bulk acoustic wave resonant structure of the original structure and the parameter comparison group are used. The second width L1 = 1μm and the second distance L2 = 1μm of the suspended bump are used as the parameter control group of the third preferred parameter group to study the influence of the second width L1 of the suspended bump and the second distance L2 of the suspended bump from the resonator (or the effective resonant area) on the performance of a bulk acoustic wave resonant structure.

[0132] As shown in Table 4: the larger the second distance L2 between the suspended bump column and the resonator (or effective resonant area), the lower the Q value and the smaller the loss; the larger the second width L1 of the suspended bump, the lower the Q value and the greater the loss.

[0133] Table 4

[0134] Based on the above theoretical explanation and test results, the effectiveness of the suspended bump and the influence of parameter changes on performance are proposed. The preferred parameters of the suspended bump are exemplified as follows:

[0135] The first thickness H1 of the suspended bump is in the range of 0.5 μm to 5 μm, the first width W1 of the suspended bump is in the range of 1 μm to 10 μm, the first distance D1 of the suspended bump is in the range of 0.5 μm to 1.5 μm, the second width L1 of the suspended bump is in the range of 1 μm to 3 μm, and the second distance L2 of the suspended bump is in the range of 1 μm to 3 μm.

[0136] In each embodiment of the present application, a suitable resonator structure is set according to the connection method of multiple resonator circuits in the acoustic wave device. On the one hand, on the piezoelectric layer in the non-resonant region, a gap structure (including a cavity) around the outer edge of the second electrode layer is created by a suspended bump at the outer edge of the second electrode layer, thereby changing the longitudinal impedance of the gap structure area. On the other hand, the greater the mass of the suspended bump, the smaller the area of ​​the overlap with the piezoelectric layer in the non-resonant region, and the mass loading effect makes the longitudinal acoustic impedance greater. Through this structure, the acoustic wave can encounter two impedance mismatch interfaces during the lateral transmission process, further reducing the acoustic loss caused by acoustic wave leakage, and improving the global quality factor Q value of the acoustic wave device.

[0137] FIG11 is a schematic diagram of a manufacturing process of a bulk acoustic wave resonant structure provided by an embodiment of the present application. Referring to FIG11 , a second aspect of an embodiment of the present application provides a manufacturing method of a bulk acoustic wave resonant structure, comprising the following steps:

[0138] S111, providing a substrate;

[0139] S112, forming a reflective structure, a first electrode layer, a piezoelectric layer, and a second electrode layer stacked sequentially on the substrate;

[0140] S113. Form a suspended bump on the piezoelectric layer outside the edge area, which surrounds at least the first area and has a gap structure between the piezoelectric layer of the first area and the second electrode layer; the top surface of the suspended bump is higher than the top surface of the second electrode layer; wherein the first area includes a partial non-resonant area adjacent to the resonant area.

[0141] 12 , the reflective structure 102 includes a first electrode layer 103 protruding upwards and forming a first cavity between the first electrode layer 103 and the surface of the substrate 101 . Here and below, the cavity-type reflective structure 102 is used as an example for description.

[0142] Execute steps S111 to S112. Referring to FIG12 , the manufacturing methods for substrate 101, reflective structure 102, first electrode layer 103, piezoelectric layer 104, and second electrode layer 105 are relatively mature in related technologies and are only briefly described here, with a focus on the formation of suspended bumps 106 on the piezoelectric layer. The constituent materials of substrate 101, reflective structure 102, first electrode layer 103, piezoelectric layer 104, and second electrode layer 105 can be found in the descriptions of FIG1 to FIG5 above and are not further elaborated here.

[0143] Figures 12 to 15 are schematic cross-sectional views of the process of the first method for manufacturing a bulk acoustic wave resonant structure provided in an embodiment of the present application. Figures 16 to 18 are schematic cross-sectional views of the process of the second method for manufacturing a bulk acoustic wave resonant structure provided in an embodiment of the present application. Figures 19 to 21 are schematic cross-sectional views of the process of the third method for manufacturing a bulk acoustic wave resonant structure provided in an embodiment of the present application. The process of the manufacturing method shown in Figures 16 to 18 can be understood as being carried out on the basis of the structure shown in Figure 12. The process of the manufacturing method shown in Figures 19 to 21 can also be understood as being carried out on the basis of the structure shown in Figure 12.

[0144] 12 to 15 , or 16 to 18 , or 19 to 21 , in some embodiments, the resonant region includes an effective region and a second region A2 located between the effective region and the non-resonant region; the third region A3 includes a portion of the effective region adjacent to the second region A2; the first region A1, the second region A2, and the third region A3 constitute an edge region;

[0145] Forming the suspended bump 106 includes:

[0146] A suspended bump 106 is formed on the piezoelectric layer 104 outside the edge area, and surrounds the edge area; a gap structure exists between the suspended bump 106 and the piezoelectric layer 104 in the first area A1, the side wall of the second electrode layer 105 in the second area A2, and the top surface of the second electrode layer 105 in the third area A3.

[0147] 12 to 15 , step S113 is performed. In some embodiments, the gap structure includes an air gap space. Forming the suspended bump 106 around the edge region includes:

[0148] 13 , a first dielectric layer 202 is formed to cover the edge region; the material of the first dielectric layer 202 includes a low acoustic impedance material;

[0149] 14 , a suspended bump 106 is formed to cover the first dielectric layer 202 and the top surface of a portion of the piezoelectric layer 104 outside the edge region;

[0150] 15 , at least a portion of the first dielectric 202 is removed to obtain an air gap space;

[0151] The suspended bump 106 is at least partially separated from the second electrode layer 105 and the piezoelectric layer 104 in the edge region by an air gap; the suspended bump 106 contacts a portion of the piezoelectric layer 104 outside the edge region.

[0152] Here, the material of the suspended bump 106 can be the same as or different from the material of the second electrode layer 105. The material of the suspended bump 106 can be high acoustic impedance metal materials such as Mo, Ag, and Al. The material of the second dielectric layer 204 is low acoustic impedance material. The material of the first dielectric layer 202 can specifically include but is not limited to SiO2.

[0153] Exemplarily, the gap structure obtained by removing all the first dielectric 202 is an air gap, and the suspended bump 106 is separated from the top surface of the piezoelectric layer 104 outside the edge area and the sidewall and top surface of the second electrode layer 105 in the edge area by the air gap.

[0154] Here, from the top surface of the second electrode layer 105 in the edge area, toward the side wall of the second electrode layer 105 in the edge area, and then toward the top surface of the piezoelectric layer 104 outside the edge area, at least a portion of the first medium 202 is removed to obtain an air gap space, and the obtained gap structure includes an air gap and a portion of the first medium 202.

[0155] Exemplarily, the gap structure obtained by removing at least part of the first dielectric 202 on the top surface of the second electrode layer 105 located in the edge area is composed of an air gap and part of the first dielectric 202, and the first dielectric 202 separates the suspended bump 106 from the top surface of the part of the piezoelectric layer 104 outside the edge area and the side wall of the second electrode layer 105 in the edge area. The suspended bump 106 and the top surface of the second electrode layer 105 in the edge area are at least partially separated by an air gap.

[0156] 16 to 18 , step S113 is performed. In some embodiments, the gap structure includes an air gap space; forming a suspended bump 106 around the edge region includes:

[0157] 16 , a second dielectric layer 204 is formed to cover the edge region and a portion of the piezoelectric layer 104 outside the edge region; the material of the second dielectric layer 204 includes a low acoustic impedance material;

[0158] 17 , a suspended bump 106 is formed covering the second dielectric layer 204 ;

[0159] 18 , at least a portion of the second dielectric layer 204 is removed to obtain an air gap space;

[0160] The suspended bump 106 is at least partially separated from the second electrode layer 105 and the piezoelectric layer 104 in the edge region by an air gap. The suspended bump 106 is separated from the piezoelectric layer 104 outside the edge region by the unremoved portion of the second dielectric layer 204 .

[0161] Here, the material of the suspended bump 106 can be the same as or different from the material of the second electrode layer 105. The material of the suspended bump 106 can be high acoustic impedance metal materials such as Mo, Ag, and Al. The material of the second dielectric layer 204 can be low acoustic impedance material, including but not limited to Si3N4.

[0162] Here, from the top surface of the second electrode layer 105 in the edge area, toward the side wall of the second electrode layer 105 in the edge area, and then toward the top surface of the piezoelectric layer 104 outside the edge area, at least a portion of the first medium 202 is removed to obtain an air gap space, and the obtained gap structure includes an air gap and a portion of the first medium 202.

[0163] Exemplarily, the gap structure obtained by removing at least part of the second dielectric 204 on the top surface of the second electrode layer 105 located in the edge area is composed of an air gap and part of the second dielectric 204, and the second dielectric 204 separates the suspended bump 106 from the top surface of the part of the piezoelectric layer 104 outside the edge area and the side wall of the second electrode layer 105 in the edge area. The suspended bump 106 and the top surface of the second electrode layer 105 in the edge area are at least partially separated by an air gap.

[0164] In this way, the structural stability of the suspended bump 106 can be enhanced, and the edge of the second electrode layer 105 can be protected in subsequent processes.

[0165] 19 to 21 , step S113 is performed. In some embodiments, the gap structure includes an air gap space; forming a suspended bump 106 around the edge region includes:

[0166] 19 , a first sacrificial layer 206 is formed to cover the edge region; the material of the first sacrificial layer 206 includes a low acoustic impedance material;

[0167] 19 , a third dielectric layer 208 is formed covering a portion of the top surface of the piezoelectric layer 104 outside the edge region and adjacent to the first sacrificial layer 206 ; the material of the third dielectric layer 208 includes a low acoustic impedance material; the material of the first sacrificial layer 206 is different from the material of the third dielectric layer 208 ;

[0168] 20 , a suspended bump is formed covering the top surfaces of the first sacrificial layer 206 and the third dielectric layer 208 ;

[0169] 21 , at least a portion of the first sacrificial layer 206 is removed to obtain an air gap space;

[0170] The suspended bump 106 is at least partially separated from the second electrode layer 105 and the piezoelectric layer 104 in the edge region by an air gap. The suspended bump 106 is electrically isolated from the portion of the piezoelectric layer 104 outside the edge region by the third dielectric layer 208 .

[0171] Here, the material of the suspended bump 106 can be the same as or different from the material of the second electrode layer 105. The material of the suspended bump 106 can be a high-acoustic-impedance metal material such as Mo, Ag, or Al. The material of the first sacrificial layer 206 includes a low-acoustic-impedance material, and the material of the first dielectric layer 202 can specifically include, but is not limited to, SiO2. The material of the third dielectric layer 208 includes a low-acoustic-impedance material, and the material of the third dielectric layer 208 can specifically include, but is not limited to, Si3N4.

[0172] Exemplarily, the gap structure formed by removing all of the first sacrificial layer 206 is an air gap, separating the suspended bump 106 from the top surface of the portion of the piezoelectric layer 104 outside the edge region and the sidewalls and top surface of the second electrode layer 105 in the edge region. The remaining third dielectric layer 208 can be understood as the aforementioned spacer 1063.

[0173] Here, from the top surface of the second electrode layer 105 in the edge area, toward the side wall of the second electrode layer 105 in the edge area, and then toward the top surface of the piezoelectric layer 104 outside the edge area, at least a portion of the first sacrificial layer 206 is removed to obtain an air gap space, and the obtained gap structure includes an air gap and a portion of the first sacrificial layer 206.

[0174] Exemplarily, the gap structure obtained by removing at least part of the first sacrificial layer 206 on the top surface of the second electrode layer 105 located in the edge area is composed of an air gap and part of the first sacrificial layer 206, and the first medium 202 separates the suspended bump 106 from the top surface of the part of the piezoelectric layer 104 outside the edge area and the side wall of the second electrode layer 105 in the edge area, and the suspended bump 106 and the top surface of the second electrode layer 105 in the edge area are at least partially separated by an air gap.

[0175] The bulk acoustic wave resonant structure obtained by the manufacturing method of the above-mentioned bulk acoustic wave resonant structure, with reference to Figure 15, or Figure 18, or Figure 21, in which the gap structure including the air gap in the bulk acoustic wave resonant structure is only an example of an embodiment of the present application, and is not used to limit the characteristics of the bulk acoustic wave resonant structure in the embodiment of the present application. Other examples of the bulk acoustic wave resonant structure in the embodiment of the present application are also shown in the following embodiments.

[0176] 15, 18, or 21, in some embodiments, the gap structure comprises an air gap and / or a low acoustic impedance material. For example, the gap structure comprises an air gap, or the gap structure comprises an air gap and a low acoustic impedance material.

[0177] 12 to 15 , or 16 to 18 , or 19 to 21 , in some embodiments, forming the suspended bump 106 further includes:

[0178] A suspended bump 106 is formed to cover the top surface of the lead 1051 of the portion of the second electrode layer 105 outside the edge region; the suspended bump 106 contacts and is electrically connected to the lead 1051 of the portion of the second electrode layer outside the edge region.

[0179] Here, the suspended bump 106 is in contact with and electrically connected to the lead 1051 of the second electrode layer. The capacitance introduced in the active region is in phase with the electrical characteristics of the resonator, so no additional parasitic resonance is introduced.

[0180] For other parts not mentioned in the method for manufacturing the BAW resonant structure in the embodiment of the present application, reference can be made to the description in the aforementioned embodiment of the BAW resonant structure, and no further details will be given here.

[0181] It should be noted that this application proposes the effectiveness of suspended bumps and the influence of parameter changes on performance based on theoretical explanations and experimental results, but the actual optimal parameters need to be selected according to the actual process.

[0182] Those skilled in the art will appreciate that the above-described embodiments are specific examples of implementing the present application. In actual applications, various modifications may be made to the embodiments in form and detail without departing from the spirit and scope of the present application. Any modifications or substitutions that can be readily conceived by those skilled in the art within the technical scope disclosed in the present application shall be included within the scope of protection of the present application. Industrial Applicability

[0183] The present invention provides a bulk acoustic wave resonant structure and a method for manufacturing the same. The bulk acoustic wave resonant structure allows acoustic waves to encounter two impedance-mismatched interfaces during lateral transmission, further reducing acoustic losses caused by acoustic wave leakage and improving the global quality factor (Q) of acoustic wave devices.

Claims

1. A bulk acoustic wave resonance structure, comprising: substrate; A reflective structure, a first electrode layer, a piezoelectric layer, and a second electrode layer sequentially stacked on the substrate; A suspended bump is located on the piezoelectric layer outside the edge area, and at least surrounds the edge area and has a gap structure between the piezoelectric layer in the edge area and the second electrode layer; the top surface of the suspended bump is higher than the top surface of the second electrode layer; wherein the edge area includes a partial non-resonant area adjacent to the resonant area.

2. The resonant structure according to claim 1, wherein: A width of a portion where the suspended bump contacts the piezoelectric layer is smaller than a width of a portion where the suspended bump contacts the piezoelectric layer.

3. The resonant structure according to claim 1, wherein: The resonance region includes an effective region and a second region located between the effective region and the non-resonance region; a portion of the non-resonance region adjacent to the second region is the first region; The suspended bump surrounds the first region or surrounds the first region and the second region, and has a gap structure between the suspended bump and the side walls of the piezoelectric layer of the first region and the second electrode layer of the second region.

4. The resonant structure according to claim 1, wherein: The resonance region includes an effective region and a second region located between the effective region and the non-resonance region; the third region includes a portion of the effective region adjacent to the second region; the first region, the second region and the third region constitute the edge region; The suspended bump surrounds the edge region, and has a gap structure between the piezoelectric layer of the edge region, the side wall of the second electrode layer, and the top surface of the second electrode layer.

5. The resonant structure according to claim 4, wherein: The suspended bump also includes an extension portion; the extension portion surrounds the fourth region and has a gap structure between the piezoelectric layer of the fourth region and the second electrode layer lead of the fourth region; the fourth region includes a partial non-resonant area located outside the contact area between the suspended bump and the piezoelectric layer.

6. The resonant structure according to claim 5, wherein: The extension portion extends along the width and height directions of the suspended bump, and / or the extension portion extends along the top surface of the piezoelectric layer.

7. The resonant structure according to any one of claims 4 to 6, wherein: The ratio of the thickness of the suspended bump located in the third region to the thickness of the second electrode layer is in a range of 1-50.

8. The resonant structure according to any one of claims 4 to 6, wherein: The suspended bump located in the third region has a first thickness and a first width; the first thickness and the first width are in the range of 0.5 μm to 5 μm and 1 μm to 10 μm, respectively.

9. The resonant structure according to any one of claims 4 to 6, wherein: There is a first distance between the suspended bump located in the third region and the top surface of the resonance region structure; and a ratio of the first distance to the thickness of the second electrode layer is in a range of 1-15.

10. The resonant structure according to any one of claims 4 to 6, wherein: There is a first distance between the suspended bump located in the third region and the edge of the resonance region; the first distance ranges from 0.5 μm to 1.5 μm.

11. The resonant structure according to any one of claims 1 to 6, wherein: The suspended bump includes a first bump column extending to a portion of the piezoelectric layer outside the edge region; the material of the first bump column includes a conductive material and / or an insulating material; or, The suspended bump includes a second bump column extending onto the pad; wherein the pad is located on a portion of the piezoelectric layer outside the edge area; the second bump column is electrically isolated from the piezoelectric layer by the pad; the material of the second bump column includes a conductive material; the material of the pad includes a low acoustic impedance material and / or an insulating material.

12. The resonant structure according to claim 10, wherein: The first bump column or the spacer has a second width; the second width ranges from 1 μm to 3 μm.

13. The resonant structure according to claim 10, wherein: There is a second distance between the first bump column or the pad and the edge of the resonance region; the second distance ranges from 1 μm to 3 μm.

14. The resonant structure according to any one of claims 1 to 6, wherein: The material of the suspended bump includes a conductive material; the material of the gap structure includes an air gap and / or a low acoustic impedance material.

15. The resonant structure according to any one of claims 1 to 6, wherein: The suspended bump is in contact with or not in contact with the lead of the second electrode layer.

16. The resonant structure according to claim 15, wherein: The suspended bump includes a connecting portion on the lead of the second electrode layer extending outside the edge region; the connecting portion is in contact with and electrically connected to the lead of the second electrode layer.

17. The resonant structure according to claim 16, wherein: The resonant structure further includes a frequency modulation layer; the suspended bump includes a connecting portion on a lead extending to the second electrode layer outside the edge region; The frequency modulation layer covers the second electrode layer, and the connecting portion is in contact with and electrically connected to the lead of the second electrode layer; or, The frequency modulation layer covers the second electrode layer and the lead of the second electrode layer, and the connecting portion penetrates the frequency modulation layer and contacts and is electrically connected to the lead of the second electrode layer.

18. The resonant structure according to claim 17, wherein: The suspended bump located in the resonance region has a first thickness; the ratio of the first thickness to the sum of the thickness of the second electrode layer and the thickness of the frequency modulation layer is in the range of 0.5-5.

19. The resonant structure according to claim 17, wherein: The sum of the thickness of the second electrode layer and the thickness of the frequency modulation layer is less than or equal to 1 μm.

20. The resonant structure according to any one of claims 1 to 6, wherein: The second electrode layer has an inclined side surface.

21. A method for manufacturing a bulk acoustic wave resonance structure, comprising: providing a substrate; forming a reflective structure, a first electrode layer, a piezoelectric layer, and a second electrode layer stacked sequentially on the substrate; A suspended bump is formed on the piezoelectric layer outside the edge area, at least surrounding the edge area and having a gap structure between the piezoelectric layer in the edge area and the second electrode layer; the top surface of the suspended bump is higher than the top surface of the second electrode layer; wherein the edge area includes a partial non-resonant area adjacent to the resonant area.

22. The method according to claim 21, wherein: The resonance region includes an effective region and a second region located between the effective region and the non-resonance region; the first region includes a portion of the non-resonance region adjacent to the second region; and the third region includes a portion of the effective region adjacent to the second region. The first area, the second area and the third area constitute the edge area; The method of forming the suspended bump includes: forming a suspended bump on the piezoelectric layer outside the edge region, and surrounding the edge region; A gap structure is formed between the suspended bump and the piezoelectric layer in the edge region, the side wall of the second electrode layer in the second region, and the top surface of the second electrode layer in the third region.

23. The method according to claim 22, wherein: The gap structure includes an air gap space; forming a suspended bump around the edge area, including: forming a first dielectric layer covering the edge region; the material of the first dielectric layer comprises a low acoustic impedance material; forming the suspended bump covering the first dielectric layer and the top surface of a portion of the piezoelectric layer outside the edge region; At least a portion of the first dielectric layer is removed to obtain the air gap space; The suspended bump is at least partially separated from the second electrode layer and the piezoelectric layer in the edge region by the air gap space; and the suspended bump is in contact with a portion of the piezoelectric layer outside the edge region.

24. The method according to claim 22, wherein: The gap structure includes an air gap space; forming a suspended bump around the edge area, including: forming a second dielectric layer covering the edge region and a portion of the piezoelectric layer outside the edge region; the material of the second dielectric layer includes a low acoustic impedance material; forming the suspended bump covering the second dielectric layer; Removing at least a portion of the second dielectric layer to obtain the air gap space; The suspended bump is at least partially separated from the second electrode layer and the piezoelectric layer in the edge region by the air gap space; the suspended bump is separated from the piezoelectric layer outside the edge region by the unremoved portion of the second dielectric layer.

25. The method of claim 22, wherein: The gap structure includes an air gap space; forming a suspended bump around the edge area, including: forming a first sacrificial layer covering the edge region; the material of the first sacrificial layer comprises a low acoustic impedance material; forming a third dielectric layer covering the top surface of a portion of the piezoelectric layer outside the edge region and adjacent to the first sacrificial layer; the material of the third dielectric layer comprises a low acoustic impedance material; the material of the first sacrificial layer is different from the material of the third dielectric layer; forming the suspended bump covering the top surfaces of the first sacrificial layer and the third dielectric layer; removing at least a portion of the first sacrificial layer to obtain the air gap space; The suspended bump is at least partially separated from the second electrode layer and the piezoelectric layer in the edge region by the air gap space; the suspended bump is electrically isolated from a portion of the piezoelectric layer outside the edge region by the third dielectric layer.

26. The method according to any one of claims 23 to 25, wherein: The method further comprises: forming the suspended bump; The suspended bump is formed to cover the top surface of the lead of the portion of the second electrode layer outside the edge area; the suspended bump is in contact with and electrically connected to the lead of the portion of the second electrode layer outside the edge area.

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