Bulk acoustic wave resonator structure and manufacturing method thereof, and acoustic wave device

Abstract

An embodiment of the present invention provides a bulk acoustic wave resonator structure, a manufacturing method thereof, and an acoustic wave device, the bulk acoustic wave resonator structure comprising: a substrate; a reflecting structure, a first electrode, a piezoelectric layer, and a second electrode sequentially arranged on the substrate, the reflecting structure, the first electrode, the piezoelectric layer, and the second electrode, the effective area of ​​a resonator region being a first overlapping region; and a first surrounding structure surrounding the first overlapping region, the first surrounding structure including a first protruding structure and a first discontinuous structure arranged at intervals, the first protruding structure being arranged between the piezoelectric layer and the first electrode and / or between the piezoelectric layer and the second electrode, and one end of each of the first protruding structures adjacent to the first overlapping region being covered by the first electrode and / or the second electrode.

Description

[Technical field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application is based on a U.S. provisional patent application, serial number 63 / 262,586, filed on October 15, 2021, and claims priority to that U.S. provisional patent application, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to the field of semiconductor technology, and in particular to a bulk acoustic wave resonator structure and a method for fabricating the same, and an acoustic wave device. [Background technology]

[0003] Widely used communication devices such as mobile phones usually include filters that use acoustic wave devices that use acoustic waves. Examples of acoustic wave devices include devices that use surface acoustic waves (SAW) or devices that use bulk acoustic waves (BAW). The performance of the acoustic wave device affects the communication effect of the communication device.

[0004] With the development of communication technology, the issue of how to improve the performance of acoustic wave devices in accordance with the progress in integration and miniaturization of communication equipment has become an issue to be resolved. Summary of the Invention

[0005] According to a first aspect, an embodiment of the present invention provides a bulk acoustic wave resonator structure, the structure comprising: A substrate; A reflection structure, a first electrode, a piezoelectric layer, and a second electrode sequentially arranged on a substrate, the reflection structure, the first electrode, the piezoelectric layer, and the second electrode, the effective area of ​​the resonance region being a first overlapping area; a first surrounding structure surrounding the first overlap region, the first surrounding structure including a first protruding structure and a first discontinuous structure arranged in a spaced apart relationship; The first protruding structures are disposed between the piezoelectric layer and the first electrode and / or between the piezoelectric layer and the second electrode, and one end of each first protruding structure adjacent to the first overlapping region is covered by the first electrode and / or the second electrode.

[0006] According to a second aspect, an embodiment of the present invention provides an acoustic wave device comprising a bulk acoustic wave resonator structure according to any of the above embodiments.

[0007] According to a third aspect, an embodiment of the present invention provides a method for manufacturing a bulk acoustic wave resonator structure, the method comprising: Providing a substrate and forming a sacrificial layer on a surface of the substrate; forming a first electrode and a piezoelectric layer overlying a sacrificial layer; forming a protruding layer of material on a side of the piezoelectric layer relatively remote from the substrate; forming a second electrode covering the protruding material layer, where the active area of ​​the resonance region is the first overlapping region; Etching the second electrode and the protruding material layer at edges of the first overlapping region to form spaced apart first protruding structures and first discontinuous structures, the first protruding structures and the first discontinuous structures forming a first surrounding structure surrounding the first overlapping region, one end of each first protruding structure adjacent to the first overlapping region being covered by the second electrode; forming at least one etching hole and removing the sacrificial layer through the etching hole to form a reflective structure.

[0008] According to a fourth aspect, an embodiment of the present invention provides a method for manufacturing a bulk acoustic wave resonator structure, the method comprising: Providing a substrate and forming a sacrificial layer on a surface of the substrate; forming a first electrode overlying the sacrificial layer; forming a protruding material layer on the first electrode; forming a piezoelectric layer overlying the protruding material layer and the first electrode; forming a second electrode covering the piezoelectric layer, the effective area of ​​the resonance region being the first overlapping area; Etching the second electrode, the piezoelectric layer and the protruding material layer at an edge of the first overlapping region to form spaced apart first protruding structures and first discontinuous structures, the first protruding structures and the first discontinuous structures forming a first surrounding structure surrounding the first overlapping region, and one end of each first protruding structure adjacent to the first overlapping region being covered by the first electrode; forming at least one etching hole and removing the sacrificial layer through the etching hole to form a reflective structure.

[0009] According to a fifth aspect, an embodiment of the present invention provides a method for manufacturing a bulk acoustic wave resonator structure, the method comprising: Providing a substrate and forming a sacrificial layer on a surface of the substrate; forming a first electrode and a piezoelectric layer overlying a sacrificial layer; forming a spaced apart sacrificial material structure and a first discontinuous structure on a side of the piezoelectric layer relatively away from the substrate; forming a second electrode covering the sacrificial material structure and the first discontinuous structure, where an active area of ​​the resonance region is a first overlap region; forming at least one etching hole, and removing the sacrificial material structure and the sacrificial layer through the etching hole to form a first protruding structure and a reflective structure, respectively, wherein the first protruding structure and the first discontinuous structure form a first surrounding structure surrounding the first overlapping region, and one end of each first protruding structure adjacent to the first overlapping region is covered by the second electrode. [Brief description of the drawings]

[0010] [Figure 1] 1 illustrates an exemplary top view of a bulk acoustic wave resonator structure in accordance with an embodiment of the present invention. [Diagram 2] 1 shows a first schematic diagram of a cross-section of a bulk acoustic wave resonator structure according to an embodiment of the present invention; [Diagram 3] 2 shows a second schematic diagram of a cross-section of a bulk acoustic wave resonator structure according to an embodiment of the present invention. [Figure 4] 2 illustrates an exemplary top view of another bulk acoustic wave resonator structure in accordance with an embodiment of the present invention. [Diagram 5] 3 shows a third schematic diagram of a cross-section of a bulk acoustic wave resonator structure according to an embodiment of the present invention. [Figure 6] 4 shows a fourth schematic diagram of a cross-section of a bulk acoustic wave resonator structure according to an embodiment of the present invention. [Figure 7] 2 illustrates an exemplary top view of yet another bulk acoustic wave resonator structure in accordance with an embodiment of the present invention. [Figure 8] FIG. 5 shows a fifth schematic diagram of a cross-section of a bulk acoustic wave resonator structure according to an embodiment of the present invention. [Figure 9] FIG. 6 shows a sixth schematic diagram of a cross section of a bulk acoustic wave resonator structure according to an embodiment of the present invention. [Figure 10] FIG. 7 shows a seventh schematic diagram of a cross section of a bulk acoustic wave resonator structure according to an embodiment of the present invention. [Figure 11] FIG. 8 shows a schematic diagram of a cross section of a bulk acoustic wave resonator structure according to an embodiment of the present invention. [Figure 12] FIG. 9 shows a ninth schematic diagram of a cross section of a bulk acoustic wave resonator structure according to an embodiment of the present invention. [Figure 13] FIG. 10 shows a tenth schematic diagram of a cross section of a bulk acoustic wave resonator structure according to an embodiment of the present invention. [Figure 14] FIG. 11 shows an eleventh schematic diagram of a cross section of a bulk acoustic wave resonator structure according to an embodiment of the present invention. [Figure 15] FIG. 12 shows a twelfth schematic diagram of a cross section of a bulk acoustic wave resonator structure according to an embodiment of the present invention. [Figure 16] FIG. 13 shows a schematic diagram of a cross section of a bulk acoustic wave resonator structure according to an embodiment of the present invention. [Figure 17] FIG. 14 shows a fourteenth schematic diagram of a cross section of a bulk acoustic wave resonator structure according to an embodiment of the present invention. [Figure 18] FIG. 15 shows a schematic diagram of a cross section of a bulk acoustic wave resonator structure according to an embodiment of the present invention. [Figure 19] FIG. 16 shows a schematic diagram of a cross section of a bulk acoustic wave resonator structure according to an embodiment of the present invention. [Figure 20] FIG. 17 shows a schematic diagram of a cross section of a bulk acoustic wave resonator structure according to an embodiment of the present invention. [Figure 21]2 illustrates an exemplary flow chart of a method for manufacturing a bulk acoustic wave resonator structure in accordance with an embodiment of the present invention. [Figure 22a] 1A-1D show first schematic diagrams of cross sections corresponding to a process of a method for manufacturing a bulk acoustic wave resonator structure according to an embodiment of the present invention. [Figure 22b] 1A-1D show first schematic diagrams of cross sections corresponding to a process of a method for manufacturing a bulk acoustic wave resonator structure according to an embodiment of the present invention. [Figure 22c] 1A-1D show first schematic diagrams of cross sections corresponding to a process of a method for manufacturing a bulk acoustic wave resonator structure according to an embodiment of the present invention. [Fig. 22d] 1A-1D show first schematic diagrams of cross sections corresponding to a process of a method for manufacturing a bulk acoustic wave resonator structure according to an embodiment of the present invention. [Figure 23a] 3A-3D show second schematic diagrams of cross sections corresponding to the process of a method for manufacturing a bulk acoustic wave resonator structure according to an embodiment of the present invention. [Figure 23b] 3A-3D show second schematic diagrams of cross sections corresponding to the process of a method for manufacturing a bulk acoustic wave resonator structure according to an embodiment of the present invention. [Figure 23c] 3A-3D show second schematic diagrams of cross sections corresponding to the process of a method for manufacturing a bulk acoustic wave resonator structure according to an embodiment of the present invention. [Figure 23d] 3A-3D show second schematic diagrams of cross sections corresponding to the process of a method for manufacturing a bulk acoustic wave resonator structure according to an embodiment of the present invention. [Figure 24] 1 shows a schematic diagram of a Smith chart test result of a bulk acoustic wave resonator structure according to an embodiment of the present invention. [Diagram 25] 4 shows a schematic diagram of another Smith chart test result of a bulk acoustic wave resonator structure according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] In the drawings, unless otherwise specified, the same reference numbers in multiple drawings indicate the same or similar parts or elements. The drawings are not necessarily drawn to scale. It should be understood that the drawings depict only some embodiments according to the present application and should not be construed as limiting the scope of the present application.

[0012] The technical solutions of the present invention are described in further detail below with reference to the accompanying drawings and specific embodiments.

[0013] In the embodiments of the present invention, the terms "first", "second", etc. are used to distinguish between similar objects and are not used to describe a particular order or chronology.

[0014] In the embodiments of the present invention, the term "A contacts B" includes the case where A contacts B directly, and the case where A and B contact each other indirectly with another part interposed between them.

[0015] In the present embodiment, the term "layer" refers to a portion of material that includes a region having a thickness. A layer may extend throughout an entire lower or upper structure, or may have an extent that is less than the extent of the lower or upper structure. Furthermore, a layer may be a homogeneous or heterogeneous region of a continuous structure that has a thickness that is less than the thickness of the continuous structure. For example, a layer may be disposed between a top surface and a bottom surface of a continuous structure, or a layer may be disposed between any horizontal plane of a top surface and a bottom surface of a continuous structure. A layer may extend along horizontal, vertical and / or inclined planes. A layer may also include multiple sub-layers.

[0016] As will be appreciated, the meaning of "on", "on" and "above" in this invention should be interpreted in the broadest possible way, and "on" not only includes being "on" something with no intermediate features or layers (i.e., directly on top of something), but also being "on" something with intermediate features or layers between them.

[0017] The resonators include dielectric resonators, surface acoustic wave resonators and bulk acoustic wave resonators. Dielectric resonators have the advantage of large power capacity, but their large volume makes them difficult to keep up with the progress of chip miniaturization and integration. In addition, in the current mobile communication field, as the frequency difference between different frequency bands becomes smaller and smaller, the requirements for the signal selectivity of filters are increasing, so the devices need to have a higher quality factor (Q value).

[0018] Surface acoustic wave resonators are widely used in commercial products due to their high operating frequency, low phase noise, high Q factor, low insertion loss, and simple manufacturing process in the 2 GHz frequency band and below. However, with the development of 5G communication, the size limitation of the interdigital electrode limits the application of surface acoustic wave resonators in the high-frequency communication field.

[0019] The resonant frequency of a bulk acoustic wave resonator depends on various factors such as the piezoelectric material, the influence of different manufacturing methods and manufacturing processes, especially the material thickness of the piezoelectric material. Bulk acoustic wave resonators can achieve much higher operating frequencies than surface acoustic wave resonators, and their size also becomes smaller as the frequency increases, so they have the advantage of small volume, and play an important role in the field of communications. Among them, the thin film bulk acoustic wave resonator (FBAR), a type of bulk acoustic wave resonator, has been greatly improved with the development of communication technology, and related filters, duplexers, etc. have been commercially applied on a large scale in the field of high-frequency communications.

[0020] There are many parameters to measure the performance of thin film bulk acoustic wave resonators, the main one includes the quality factor (Q value). When electrical energy is applied to the top and bottom electrodes of a bulk acoustic wave resonator, the piezoelectric layer located on the top and bottom electrodes generates elastic waves due to the piezoelectric effect. In addition to longitudinal waves, transverse shear waves (transverse shear waves are also called transverse waves or shear waves) are also generated in the piezoelectric layer. The existence of transverse shear waves affects the energy of the main longitudinal wave, and the transverse shear waves cause energy loss and deteriorate the Q value of the bulk acoustic wave resonator.

[0021] For example, in a mobile terminal, multiple frequency bands may be used simultaneously, so a filter or duplexer in the mobile terminal needs to have a steep skirt and smaller insertion loss. The performance of the filter is determined by the resonators that make up the filter, and a steep skirt and small insertion loss can be achieved by increasing the Q value of the resonators. In addition, excessive parasitic resonance of the resonators also adversely affects the performance of the filter or duplexer.

[0022] In view of this, how to reduce the parasitic resonance of a bulk acoustic wave resonator and increase the Q value of the bulk acoustic wave resonator has become an issue to be resolved.

[0023] Fig. 1 shows an exemplary top view of a bulk acoustic wave resonator structure 100 according to an embodiment of the present invention, and Fig. 2 shows a schematic cross-sectional view of the bulk acoustic wave resonator structure 100 along the A-A' direction shown in Fig. 1. Referring to Fig. 2, the bulk acoustic wave resonator structure 100 includes: A substrate 101; A reflecting structure 102, a first electrode 103, a piezoelectric layer 104 and a second electrode 105 arranged in this order on a substrate 101, the reflecting structure 102, the first electrode 103, the piezoelectric layer 104 and the second electrode 105 having an effective resonance region as a first overlap region 106; a first surrounding structure (107) surrounding the first overlap region (106), the first surrounding structure (107) including a first protruding structure (171) and a first discontinuous structure (172) arranged at intervals; The first protruding structures 171 are arranged between the piezoelectric layer 104 and the first electrode 103 and / or between the piezoelectric layer 104 and the second electrode 105, and one end of each first protruding structure 171 adjacent to the first overlap region 106 is covered by the first electrode 103 and / or the second electrode 105.

[0024] In order to intuitively explain the position of each part of the first surrounding structure 107, the bulk acoustic wave resonator 100 shown in FIG. 2 is a schematic diagram of a partial cross section with the first surrounding structure 107 highlighted. The bulk acoustic wave resonator shown in FIG. 2 is merely an example of an embodiment of the present invention, and is not intended to limit the features of the bulk acoustic wave resonator in the embodiment of the present invention, and other examples of the bulk acoustic wave resonator in the embodiment of the present invention are also shown in the subsequent embodiments. FIG. 2 shows an example in which the first protruding structure 171 is disposed between the piezoelectric layer 104 and the second electrode 105.

[0025] In practical applications, the constituent material of the substrate 101 may include silicon (Si), germanium (Ge), and so on.

[0026] Exemplarily, the first electrode 103 is also called a bottom electrode, and the second electrode 105 is also called a top electrode, and electrical energy can be applied to the bulk acoustic wave resonator structure 100 through the top and bottom electrodes. The first electrode 103 and the second electrode 105 may be made of the same material, which may include a conductive material such as aluminum (Al), molybdenum (Mo), ruthenium (Ru), iridium (Ir), chromium (Cr) or platinum (Pt) or an alloy of the above conductive metals. Exemplarily, the first electrode 103 and the second electrode 105 are both made of molybdenum (Mo).

[0027] In practical applications, the piezoelectric layer 104 can be used to generate vibrations according to the inverse piezoelectric characteristic, convert the electrical signal applied to the first electrode 103 and the second electrode 105 into an elastic wave signal, and realize the conversion from electrical energy to mechanical energy.

[0028] Exemplarily, the constituent material of the piezoelectric layer 104 includes a material having piezoelectric properties, such as aluminum nitride, zinc oxide, lithium tantalate, lead zirconate titanate, barium titanate, etc. The constituent material of the piezoelectric layer 104 may include a material having piezoelectric properties due to doping, which may be a transition metal or a rare metal, such as scandium-doped aluminum nitride.

[0029] Here, the reflecting structure 102 is configured to reflect an elastic wave signal. When the elastic wave signal generated by the piezoelectric layer 104 propagates toward the reflecting structure 102, the elastic wave signal is totally reflected at the interface where the first electrode 103 and the reflecting structure 102 contact each other, so that the elastic wave signal can be reflected to the piezoelectric layer 104. In this way, the energy of the elastic wave signal generated by the piezoelectric layer 104 can be localized within the piezoelectric layer 104, which can reduce the energy loss of the elastic wave signal and increase the elastic wave energy of the main resonant mode of the bulk acoustic wave resonant structure.

[0030] 2 is merely one example of the present invention, and in practical applications, the bulk acoustic wave resonator structure can be specifically classified into a first type cavity-type FBAR, a second type cavity-type FBAR, an SMR (Solid Mounted Resonator) type resonator structure, etc. according to the different forms of the reflecting structure 102. The solution according to the embodiment of the present invention can be applied to the above different types of bulk acoustic wave resonator structures.

[0031] Exemplarily, when the bulk acoustic wave resonator structure 100 includes a first type of cavity-type FBAR, the reflecting structure 102 includes a first cavity formed between the upward protrusion of the first electrode 103 and the surface of the substrate 101. When the bulk acoustic wave resonator structure 100 includes a second type of cavity-type FBAR, the reflecting structure 102 includes a second cavity formed between the downward recess of the surface of the substrate 101 and the first electrode 103. Here, it is taken as an example that the bulk acoustic wave resonator structure 100 includes the first type of cavity-type FBAR.

[0032] 2, in practical application, the resonance region is a superposition region of four orthogonal projections, namely, the orthogonal projection of the reflecting structure 102 on the substrate 101, the orthogonal projection of the first electrode 103 on the substrate 101, the orthogonal projection of the piezoelectric layer 104 on the substrate 101, and the orthogonal projection of the second electrode 105 on the substrate. Here, the effective region (or main resonance region) of the resonance region is the first overlap region 106, and the main resonance mode of the bulk acoustic wave resonating structure is generated within the first overlap region 106.

[0033] 1, the first surrounding structure 107 includes a first protruding structure 171 and a first discontinuous structure 172 arranged at intervals, and the first protruding structure 171 in FIG. 1 is covered by the second electrode 105 and is not shown in perspective. As shown in FIG. 1, the first protruding structure 171 is provided intermittently near the edge of the first overlapping region 106, and the first protruding structure 171 surrounds the first overlapping region 106.

[0034] 2, the first protruding structures 171 are disposed between the piezoelectric layer 104 and the second electrode 105, and one end of each of the first protruding structures 171 adjacent to the first overlapping region 106 is covered by the second electrode 105. By providing the first protruding structures 171, the distance from the second electrode 105 to the first electrode 103 in the direction perpendicular to the substrate 101 is increased within the orthogonal projection range of the first protruding structures 171, and thus the electric field lines from the second electrode 105 to the first electrode 103 are lengthened, and the electric field intensity near the edge of the first overlapping region 106 is reduced. As the electric field strength decreases, the electrical displacement decreases and the effect of piezoelectric resonance becomes smaller, thereby reducing parasitic resonance near the edge of the first overlap region 106 (i.e., which may be located inside the first overlap region 106 or outside the first overlap region 106) and reducing the propagation of parasitic resonance to the first overlap region, thereby increasing the Q value of the bulk acoustic wave resonator structure.

[0035] 3 is a schematic diagram of a partial cross section along the B-B' direction of the bulk acoustic wave resonator structure 100 shown in FIG. 1. Exemplarily, as shown in FIG. 3, the first discontinuous structure 172 may be a groove penetrating the second electrode 105, the first protruding structure 171, the piezoelectric layer 104 and the first electrode 103. By providing the first discontinuous structure 172 surrounding the first overlapping region 106, the transverse shear wave in the first overlapping region 106 can be reflected, and the energy can be concentrated in the longitudinal wave in the first overlapping region 106, thereby achieving the effect of suppressing the transverse parasitic mode (i.e., suppressing the parasitic resonance) and increasing the quality factor (Q value).

[0036] It should be noted that in some embodiments, the first protruding structure 171 of the bulk acoustic wave resonator structure may be present only on the oblique surface of the piezoelectric layer 104 (not shown).

[0037] In this embodiment, by providing a first surrounding structure 107 including a first protruding structure 171 and a first discontinuous structure 172 arranged at intervals and surrounding the first overlapping region 106, the distance between the first electrode 103 and the second electrode 105 at the edge of the first overlapping region 106 can be increased, thereby reducing the electric field strength at the edge of the first overlapping region 106. The reduced electric field strength reduces the electrical displacement and the effect of the piezoelectric resonance, thereby reducing the parasitic resonance at the edge of the first overlapping region 106 and the propagation of the parasitic resonance to the first overlapping region 106, thereby increasing the Q value of the bulk acoustic wave resonator structure. Furthermore, by providing a first discontinuous structure 172 surrounding the first overlap region 106, transverse shear waves in the first overlap region 106 can be reflected and energy can be concentrated into longitudinal waves in the first overlap region 106, thereby achieving the effect of suppressing transverse parasitic modes (i.e., suppressing parasitic resonance) and increasing the quality factor (Q value).

[0038] In some embodiments, referring to FIG. 4 , when the first protruding structure 171 is disposed only between the piezoelectric layer 104 and the second electrode 105, the bulk acoustic wave resonator structure further comprises a second surrounding structure 108 surrounding the first surrounding structure 107, The second enclosing structure 108 partially covers a sidewall of the piezoelectric layer 104 relatively remote from the reflecting structure 102 .

[0039] 4, the first surrounding structure 107 includes a first protruding structure 171 and a first discontinuous structure 172 arranged at intervals, and the first protruding structure 171 in FIG. 4 is covered by the second electrode 105 and is not shown in perspective. As shown in FIG. 4, the first protruding structure 171 is intermittently provided near the edge of the first overlapping region 106, and the first protruding structure 171 surrounds the first overlapping region 106. The second surrounding structure 108 surrounds the first surrounding structure 107.

[0040] Exemplarily, FIG. 5 is a schematic diagram of a partial cross section along the A-A' direction of the bulk acoustic wave resonator structure shown in FIG. 4. As shown in FIG. 5, the first protruding structure 171 is disposed between the piezoelectric layer 104 and the second electrode 105, and one end of each of the first protruding structures 171 adjacent to the first overlapping region 106 is covered by the second electrode 105. The second surrounding structure 108 is connected to the first protruding structure 171, and the second surrounding structure 108 has an inclination angle with respect to the surface of the substrate 101. Exemplarily, the inclination angle of the second surrounding structure 108 includes 10° to 80°. The inclination angle can also be improved according to the design size of the bulk acoustic wave resonator structure. The second surrounding structure 108 and the first protruding structure 171 form a protruding structure adjacent to the first overlapping region 106. By providing the second surrounding structure 108 and the first protruding structure 171, the distance from the second electrode 105 to the first electrode 103 in the direction perpendicular to the substrate 101 becomes longer within the orthogonal projection range of the second surrounding structure 108 and the first protruding structure 171, and as a result, the electric field lines from the second electrode 105 to the first electrode 103 become longer, and the electric field intensity in the vicinity of the first overlapping region 106 becomes smaller. When the electric field intensity becomes smaller, the electric displacement decreases and the effect of the piezoelectric resonance becomes smaller, so that the parasitic resonance in the vicinity of the edge of the first overlapping region 106 (i.e., it may be located inside or outside the first overlapping region) is reduced, and the propagation of the parasitic resonance to the first overlapping region is reduced, thereby increasing the Q value of the bulk acoustic wave resonator structure.

[0041] In one embodiment, the second surrounding structure 108 and the first protruding structure 171 are made of the same material, for example, the second surrounding structure 108 and the first protruding structure 171 are made of silicon dioxide (SiO2). In another embodiment, the second surrounding structure 108 and the first protruding structure 171 are made of different materials, for example, the second surrounding structure 108 is made of silicon dioxide (SiO2) and the first protruding structure 171 is made of silicon carbide (SiC).

[0042] Fig. 6 is a schematic diagram of a partial cross section along the B-B' direction of the bulk acoustic wave resonator structure shown in Fig. 4. Exemplarily, as shown in Fig. 6, the first discontinuous structure 172 may be a groove penetrating the second electrode 105, the first protruding structure 171, the piezoelectric layer 104 and the first electrode 103. By providing the first discontinuous structure 172 surrounding the first overlapping region 106, the transverse shear wave in the first overlapping region 106 can be reflected, and the energy can be concentrated in the longitudinal wave in the first overlapping region 106, thereby suppressing the transverse parasitic mode (i.e., suppressing the parasitic resonance) and achieving the effect of increasing the quality factor (Q value).

[0043] In this embodiment, by providing a first surrounding structure 107 and a second surrounding structure 108 surrounding the first overlap region 106, the distance between the first electrode 103 and the second electrode 105 at the edge of the first overlap region 106 is further increased, and the parasitic resonance at the edge of the first overlap region 106 is reduced, thereby reducing the propagation of the parasitic resonance to the first overlap region 106 and increasing the Q value of the bulk acoustic wave resonator structure.

[0044] In some embodiments, referring to FIG. 5, the second surrounding structure 108 and the first protruding structure 171 are made of the same material, and the second surrounding structure 108 and the first protruding structure 171 are connected to form an integrated structure.

[0045] Exemplarily, the constituent materials of the second surrounding structure 108 and the first protruding structure 171 are the same, for example, the constituent materials of the second surrounding structure 108 and the first protruding structure 171 include silicon dioxide (SiO2), or the constituent materials of the second surrounding structure 108 and the first protruding structure 171 include silicon carbide (SiC) or aluminum nitride (AlN). The present invention is not limited thereto.

[0046] In addition, the second surrounding structure 108 and the first protruding structure 171 are connected to form an integrated structure, and this integrated structure is a protruding structure close to the first overlapping region 106. As shown in FIG. 5, the first protruding structure 171 of this protruding structure is covered by the second electrode 105, and the second surrounding structure 108 of this protruding structure is disposed on the inclined surface of the piezoelectric layer 104 and is not covered by the second electrode 105.

[0047] In some embodiments, referring to FIG. 7 , the second surrounding structure 108 includes a second protruding structure 181 and a second discontinuous structure 182 arranged at a distance from each other, the first discontinuous structure 172 and the second discontinuous structure 182 are gaps, the second protruding structure 181 and the first protruding structure 171 are made of the same material, and the second protruding structure 181 and the first protruding structure 171 are connected to form an integrated structure.

[0048] 7, the first protruding structure 171 and the first discontinuous structure 172 (not shown) are covered by the second electrode 105, and the second electrode 105 is shown in a see-through manner. The first protruding structure 171 and the first discontinuous structure 172 are arranged at intervals near the edge of the first overlapping region 106. The second surrounding structure 108 surrounds the first surrounding structure 107 (not shown), and the first surrounding structure 107 in FIG. 7 is covered by the second electrode 105. The second surrounding structure 108 includes a second protruding structure 181 and a second discontinuous structure 182 arranged at intervals.

[0049] As shown in FIG. 7, the first discontinuous structure 172 and the second discontinuous structure 182 are gaps. By providing a gap surrounding the first overlapping region 106, the transverse shear waves in the first overlapping region 106 can be reflected and the energy can be concentrated into the longitudinal waves in the first overlapping region 106, thereby suppressing the transverse parasitic mode (i.e., suppressing the parasitic resonance) and achieving the effect of increasing the Q value.

[0050] FIG. 8 is a schematic diagram of a partial cross section along the A-A' direction of the bulk acoustic wave resonator structure shown in FIG. 7. As shown in FIG. 8, the first protruding structure 171 is disposed between the piezoelectric layer 104 and the second electrode 105, the first protruding structure 171 is covered by the second electrode 105, and the second protruding structure 181 is covered by an upper electrode lead connected to the second electrode 105. The second protruding structure 181 is connected to the first protruding structure 171, and the second protruding structure 181 has an inclination angle with respect to the surface of the substrate 101. Exemplarily, the inclination angle of the second protruding structure 181 includes 10° to 80°. The inclination angle can also be improved according to the design size of the bulk acoustic wave resonator structure.

[0051] 8, the second protruding structure 181 and the first protruding structure 171 are made of the same material, and are connected to each other to form an integrated structure. Exemplarily, the material of the second protruding structure 181 and the first protruding structure 171 includes silicon dioxide (SiO2). The second protruding structure 181 and the first protruding structure 171 form a protruding structure adjacent to the first overlapping region 106, and by providing the second protruding structure 181 and the first protruding structure 171, the distance from the second electrode 105 to the first electrode 103 in the direction perpendicular to the substrate 101 is increased within the orthogonal projection range of the second protruding structure 181 and the first protruding structure 171, and thus the electric field line from the second electrode 105 to the first electrode 103 is lengthened, and the electric field intensity in the vicinity of the first overlapping region 106 is reduced. As the electric field strength decreases, the electrical displacement decreases and the effect of piezoelectric resonance becomes smaller, thereby reducing parasitic resonance near the edge of the first overlap region 106 (i.e., which may be located inside the first overlap region or outside the first overlap region) and reducing the propagation of parasitic resonance into the first overlap region, thereby increasing the Q value of the bulk acoustic wave resonator structure.

[0052] Fig. 9 is a schematic diagram of a partial cross section along the B-B' direction of the bulk acoustic wave resonator structure shown in Fig. 7. Exemplarily, as shown in Fig. 9, the first protruding structures 171 are disposed between the piezoelectric layer 104 and the second electrode 105, and one end of each of the first protruding structures 171 adjacent to the first overlapping region 106 is covered by the second electrode 105. A portion of the second protruding structure 181 is covered by the upper electrode lead connected to the second electrode 105, and a portion of the second protruding structure 181 is covered by the second electrode 105.

[0053] Compared with the bulk acoustic wave resonator structure shown in FIG. 4, in this embodiment, the bulk acoustic wave resonator structure shown in FIG. 7 includes an intermittent protrusion structure and does not require forming a groove by etching, so that the etching process is eliminated in the manufacturing process, thereby saving costs.

[0054] In some embodiments, referring to FIG. 2 , when the first protruding structures 171 are disposed only between the piezoelectric layer 104 and the second electrode 105, one end of each first protruding structure 171 adjacent to the first overlapping region 106 and the other end remote from the first overlapping region 106 are both covered by the second electrode 105; Each first protruding structure 171 includes a top and a bottom opposing along a direction perpendicular to the substrate 101 , with the top in direct contact with the second electrode 105 and the bottom in direct contact with the piezoelectric layer 104 .

[0055] 2, one end of each first protruding structure 171 adjacent to the first overlapping region 106 and the other end remote from the first overlapping region 106 are both covered by the second electrode 105. Since the first protruding structure 171 is disposed on a side of the piezoelectric layer 104 relatively remote from the substrate 101 and protrudes in a direction away from the substrate 101, the second electrode 105 covering the first protruding structure 171 protrudes in a direction away from the substrate 101 in a direction perpendicular to the substrate 101, and by providing the first protruding structure 171, the distance from the second electrode 105 to the first electrode 103 in the direction perpendicular to the substrate 101 becomes longer within the orthogonal projection range of the first protruding structure 171.

[0056] In this embodiment, the electric field lines from the second electrode 105 to the first electrode 103 become longer, and the electric field strength in the vicinity of the first overlap region 106 becomes smaller. When the electric field strength becomes smaller, the electric displacement decreases and the effect of the piezoelectric resonance becomes smaller, so that the parasitic resonance in the vicinity of the edge of the first overlap region 106 (i.e., it may be located inside the first overlap region or outside the first overlap region) is reduced, and the propagation of the parasitic resonance to the first overlap region is reduced, thereby increasing the Q value of the bulk acoustic wave resonator structure.

[0057] In some embodiments, referring to FIG. 10 , when the first protruding structures 171 are disposed only between the piezoelectric layer 104 and the first electrode 103, one end of each first protruding structure 171 adjacent to the first overlapping region 106 and the other end remote from the first overlapping region 106 are both covered by the first electrode 103; Each first protruding structure 171 includes a top and a bottom opposing along a direction perpendicular to the substrate 101 , with the top in direct contact with the piezoelectric layer 104 and the bottom in direct contact with the first electrode 103 .

[0058] 10, one end of each first protruding structure 171 adjacent to the first overlapping region 106 and the other end remote from the first overlapping region 106 are both covered by the first electrode 103. Since the first protruding structure 171 is disposed on a side of the piezoelectric layer 104 relatively close to the substrate 101 and protrudes toward the substrate 101, the first electrode 103 covering the first protruding structure 171 protrudes toward the substrate 101 along a direction perpendicular to the substrate 101, and the provision of the first protruding structure 171 increases the distance from the second electrode 105 to the first electrode 103 in the direction perpendicular to the substrate 101 within the orthogonal projection range of the first protruding structure 171.

[0059] In this embodiment, the electric field lines from the second electrode 105 to the first electrode 103 become longer, and the electric field strength in the vicinity of the first overlap region 106 becomes smaller. When the electric field strength becomes smaller, the electric displacement decreases and the effect of the piezoelectric resonance becomes smaller, so that the parasitic resonance in the vicinity of the edge of the first overlap region 106 (i.e., it may be located inside the first overlap region or outside the first overlap region) is reduced, and the propagation of the parasitic resonance to the first overlap region is reduced, thereby increasing the Q value of the bulk acoustic wave resonator structure.

[0060] In some embodiments, referring to FIG. 11 , the first protruding structure 171 includes a first sub-structure 1711 and a second sub-structure 1712, The first substructures 1711 are disposed only between the piezoelectric layer 104 and the second electrode 105, and one end of each of the first substructures 1711 adjacent to the first overlapping region 106 and the other end remote from the first overlapping region 106 are both covered by the second electrode 105; The second substructures 1712 are disposed only between the piezoelectric layer 104 and the first electrode 103, and one end of each second substructure 1712 adjacent to the first overlapping region 106 and the other end remote from the first overlapping region 106 are both covered by the first electrode 103; Here, the orthogonal projection of the first substructure 1711 on the substrate 101 at least partially overlaps with the orthogonal projection of the second substructure 1712 on the substrate 101 .

[0061] 11, a plurality of first substructures 1711 are disposed between the piezoelectric layer 104 and the second electrode 105, and a plurality of second substructures 1712 are disposed between the piezoelectric layer 104 and the first electrode 103. This embodiment will be described using an example in which the orthogonal projection of the first substructure 1711 on the substrate 101 overlaps with the orthogonal projection of the second substructure 1712 on the substrate 101 in FIG. 11. Note that the positions of the first substructure 1711 and the second substructure 1712 may be changed, and the present invention is not limited thereto.

[0062] For example, one end of each of the first substructures 1711 adjacent to the first overlapping region 106 and the other end remote from the first overlapping region 106 are both covered by the second electrode 105. Since the first substructure 1711 is disposed on a side of the piezoelectric layer 104 relatively far from the substrate 101 and protrudes in a direction away from the substrate 101, the second electrode 105 covering the first substructure 1711 protrudes in a direction away from the substrate 101 along a direction perpendicular to the substrate 101, and by providing the first substructure 1711, the distance from the second electrode 105 to the first electrode 103 in the direction perpendicular to the substrate 101 is increased within the orthogonal projection range of the first substructure 1711. One end of each of the second substructures 1712 adjacent to the first overlapping region 106 and the other end remote from the first overlapping region 106 are both covered by the first electrode 103. Since the second substructure 1712 is arranged on the side of the piezoelectric layer 104 relatively closer to the substrate 101 and protrudes toward the substrate 101, the first electrode 103 covering the second substructure 1712 protrudes toward the substrate 101 along a direction perpendicular to the substrate 101, and by providing the second substructure 1712, the distance from the second electrode 105 to the first electrode 103 in the direction perpendicular to the substrate 101 is increased within the orthogonal projection range of the second substructure 1712.

[0063] In this embodiment, by providing the first substructure 1711 and the second substructure 1712, the length of the electric field lines from the second electrode 105 to the first electrode 103 is further increased, and the electric field strength in the vicinity of the first overlap region 106 is reduced. When the electric field strength is reduced, the electric displacement is reduced and the effect of the piezoelectric resonance is reduced, so that the parasitic resonance in the vicinity of the edge of the first overlap region 106 (i.e., it may be located inside or outside the first overlap region) is reduced, and the propagation of the parasitic resonance to the first overlap region is reduced, thereby increasing the Q value of the bulk acoustic wave resonator structure.

[0064] In some embodiments, the distance in a first direction between one end of the first protruding structure 171 adjacent to the first overlap region 106 and the edge of the first overlap region 106 is 0 to 10 μm, where the first direction is the direction from the edge of the first overlap region 106 toward the center of the first overlap region 106.

[0065] In one example, one end of the first protruding structure 171 adjacent to the first overlapping region 106 is flush with the edge of the first overlapping region 106, that is, the distance in the first direction between the one end of the first protruding structure 171 adjacent to the first overlapping region 106 and the edge of the first overlapping region 106 is 0. In another example, as shown in FIG. 2, the distance in the first direction between the one end of the first protruding structure 171 adjacent to the first overlapping region 106 and the edge of the first overlapping region 106 may be 5 μm. Preferably, the distance in the first direction between the one end of the first protruding structure 171 adjacent to the first overlapping region 106 and the edge of the first overlapping region 106 is 0 μm.

[0066] In addition, depending on the design size of the bulk acoustic wave resonator structure, the distance in the first direction between one end of the first protruding structure 171 adjacent to the first overlapping region 106 and the edge of the first overlapping region 106 may be improved, and the present invention is not limited thereto.

[0067] In some embodiments, referring to FIG. 1 , the bulk acoustic wave resonator structure further comprises a first electrode lead 1031 and a second electrode lead 1051, the first electrode lead 1031 being connected to the first electrode 103 and the second electrode lead 1051 being connected to the second electrode 105; The orthogonal projections of the first electrode lead 1031 and the second electrode lead 1051 on the substrate 101 are located in a region other than the first overlap region 106, The orthogonal projection of the first discontinuous structure 172 on the substrate 101 falls in an area other than the orthogonal projections of the first electrode lead 1031 and the second electrode lead 1051 on the substrate 101 .

[0068] In practical applications, the bulk acoustic wave resonator further includes a first electrode lead 1031 and a second electrode lead 1051. The first electrode lead 1031 is also called a lower electrode lead, and the second electrode lead 1051 is also called an upper electrode lead. The first electrode lead 1031 (lower electrode lead) and the first electrode 103 (lower electrode) are disposed in the same layer, and the first electrode lead 1031 is connected to the first electrode 103. The second electrode lead 1051 (upper electrode lead) and the second electrode 105 (upper electrode) are disposed in the same layer, and the second electrode lead 1051 is connected to the second electrode 105.

[0069] As shown in FIG. 1 or FIG. 4, the orthogonal projection of the first discontinuous structure 172 on the substrate 101 falls in an area other than the orthogonal projections of the first electrode lead 1031 and the second electrode lead 1051 on the substrate 101 .

[0070] In some embodiments, the bulk acoustic wave resonator structure further comprises a frequency modulation layer 109, the frequency modulation layer 109 being disposed on the second electrode 105; The first enclosing structure 107 is disposed between the frequency modulation layer 109 and the second electrode 105 .

[0071] In practical applications, the bulk acoustic wave resonating structure further comprises a frequency modulation layer 109, which is also called a tuning layer. The frequency modulation layer 109 can be used to tune the frequency of the bulk acoustic wave resonating structure.

[0072] The first surrounding structure 107 includes a first protruding structure 171 and a first discontinuous structure 172 arranged in a spaced apart relationship. In one example, the frequency modulation layer 109 covers the second electrode 105, and the first protruding structure 171 is disposed between the piezoelectric layer 104 and the second electrode 105, as shown in Figure 12. In another example, the frequency modulation layer 109 covers the second electrode 105, and the first protruding structure 171 is disposed between the frequency modulation layer 109 and the second electrode 105 (not shown).

[0073] Fig. 13 is a schematic diagram of a partial cross section along the first discontinuous structure direction of the bulk acoustic wave resonator structure shown in Fig. 12. Exemplarily, as shown in Fig. 13, the first discontinuous structure 172 may be a groove penetrating the frequency modulation layer 109, the second electrode 105, the first protruding structure 171, the piezoelectric layer 104 and the first electrode 103. By providing the first discontinuous structure 172 surrounding the first overlapping region 106, the transverse shear wave in the first overlapping region 106 can be reflected, and the energy can be concentrated in the longitudinal wave in the first overlapping region 106, thereby suppressing the transverse parasitic mode (i.e., suppressing the parasitic resonance) and achieving the effect of increasing the Q value.

[0074] For example, as shown in FIG. 14 , the frequency modulation layer 109 covers a portion of the second electrode 105, the orthogonal projection of the frequency modulation layer 109 on the substrate 101 falls within the first overlap region 106, and the first protruding structure 171 is disposed between the piezoelectric layer 104 and the second electrode 105.

[0075] It should be noted that the position of the frequency modulation layer 109 may be improved depending on the design size of the bulk acoustic wave resonator structure, and the present invention is not limited thereto.

[0076] In some embodiments, the bulk acoustic wave resonator structure further comprises a seed layer 110, the seed layer 110 being disposed between the first electrode 103 and the substrate 101; The first surrounding structure 107 is disposed between the seed layer 110 and the first electrode 103 .

[0077] In practical application, the bulk acoustic wave resonator structure further includes a seed layer 110, which is disposed between the first electrode 103 and the substrate 101. As shown in FIG. 14, before depositing the first electrode 103, a single seed layer 110 is first deposited to improve the crystal axis orientation of the lower electrode material, so that the crystal lattice is close to the piezoelectric layer 104 and the lattice defects of the subsequently deposited piezoelectric layer 104 can be reduced, while the seed layer 110 can also function as an etching stop layer for the first electrode 103. The constituent material of the seed layer 110 is the same as that of the piezoelectric layer 104.

[0078] 14, the seed layer 110 is disposed between the first electrode 103 and the substrate 101, and the first protruding structure 171 is disposed between the piezoelectric layer 104 and the second electrode 105. In another example, the seed layer 110 is disposed between the first electrode 103 and the substrate 101, and the first protruding structure 171 is disposed between the seed layer 110 and the first electrode 103 (not shown).

[0079] In some embodiments, the first discontinuous structure 172 is a groove. The groove penetrates at least one of the second electrode 105 , the first protruding structure 171 , the piezoelectric layer 104 and the first electrode 103 along a direction perpendicular to the substrate 101 .

[0080] 3, the first discontinuous structure 172 may be a groove penetrating the second electrode 105, the first protruding structure 171, the piezoelectric layer 104, and the first electrode 103. By providing a groove surrounding the first overlapping region 106, the transverse shear wave in the first overlapping region 106 can be reflected, and the energy can be concentrated into the longitudinal wave in the first overlapping region 106, thereby suppressing the transverse parasitic mode (i.e., suppressing the parasitic resonance) and increasing the Q value. Note that, when the groove penetrates the second electrode 105, the piezoelectric layer 104, and the first electrode 103 and contacts the sacrificial layer, the groove can be used as an etching hole to etch the sacrificial layer to form a cavity-type reflection structure 102.

[0081] In one embodiment, as shown in FIG. 15, a part of the first protruding structure 171 is covered by the second electrode 105 and the second electrode lead. One end of a part of the first protruding structure 171 remote from the first overlapping region 106 is flush with the edge of the second electrode 105. FIG. 16 is a schematic diagram of a partial cross section along the direction of the first discontinuous structure of the bulk acoustic wave resonator structure shown in FIG. 15. Exemplarily, as shown in FIG. 16, the first discontinuous structure 172 penetrates the second electrode 105, the first protruding structure 171, and a part of the piezoelectric layer 104. FIG. 17 is a schematic diagram of a partial cross section along the direction of the first discontinuous structure of the bulk acoustic wave resonator structure shown in FIG. 15. Exemplarily, as shown in FIG. 17, the first discontinuous structure 172 penetrates the second electrode 105, the first protruding structure 171, the piezoelectric layer 104, and the first electrode 103.

[0082] It should be noted that, when the first discontinuous structure 172 is a groove, the groove at least penetrates the first protruding structure 171. The groove surrounding the first overlapping region 106 can reflect the transverse shear wave in the first overlapping region 106 and concentrate the energy into the longitudinal wave in the first overlapping region 106, thereby achieving the effect of suppressing the transverse parasitic mode (i.e., suppressing the parasitic resonance) and increasing the quality factor (Q value).

[0083] In some embodiments, the bulk acoustic wave resonator structure further comprises a stripe structure 111, the stripe structure 111 being disposed on and connected to the second electrode 105; Orthogonal projections of the stripe structures 111 on the substrate 101 fall on an area other than the first overlapping area 106, and the stripe structures 111 are arranged surrounding the first overlapping area 106 at intervals.

[0084] In one example, referring to FIG. 18, the bulk acoustic wave resonator structure includes a striped structure 111 (Frame), which is disposed on and connected to the second electrode 105. Illustratively, the striped structure 111 and the second electrode 105 are made of the same material. The striped structure 111 forms a mass load structure. When a shear wave propagates to an overlapping region between the striped structure 111 and the second electrode 105, the transverse shear wave propagated to the overlapping region can be reflected, the leakage of the transverse shear wave can be suppressed, and the Q value of the bulk acoustic wave resonator structure can be increased.

[0085] In another example, referring to Fig. 19, a bulk acoustic wave resonator structure includes a first protruding structure 171 and a stripe structure 111 (Frame), and the first protruding structure 171 is omitted in Fig. 19. The first protruding structure 171 is disposed between the piezoelectric layer 104 and the second electrode 105, and one end of each first protruding structure 171 adjacent to the first overlapping region 106 is covered by the second electrode 105. The stripe structure 111 is disposed on the second electrode 105 and connected to the second electrode 105, and the orthogonal projection of the stripe structure 111 on the substrate 101 at least partially overlaps with the orthogonal projection of the first protruding structure 171 on the substrate 101. By providing the first protruding structure 171 and the striped structure 111, the distance from the second electrode 105 to the first electrode 103 in the direction perpendicular to the substrate 101 becomes longer within the orthogonal projection range of the first protruding structure 171 and the striped structure 111, and as a result, the electric field lines from the second electrode 105 to the first electrode 103 become longer, and the electric field intensity in the vicinity of the edge of the first overlapping region 106 becomes smaller. When the electric field intensity becomes smaller, the electric displacement decreases and the effect of the piezoelectric resonance becomes smaller, so that the parasitic resonance in the vicinity of the edge of the first overlapping region 106 (i.e., it may be located inside the first overlapping region 106 or may be located outside the first overlapping region 106) is reduced, and the propagation of the parasitic resonance to the first overlapping region is reduced, thereby increasing the Q value of the bulk acoustic wave resonator structure.

[0086] In another example, referring to FIG. 20, the bulk acoustic wave resonator structure includes a first surrounding structure 107 and a striped structure 111 (Frame), and the first surrounding structure 107 includes a first protruding structure 171 and a first discontinuous structure 172 arranged at intervals, and the first protruding structure 171 is omitted in FIG. 20. Exemplarily, as shown in FIG. 20, the first discontinuous structure 172 may be a groove penetrating the striped structure 111, the second electrode 105, the first protruding structure 171, the piezoelectric layer 104, and the first electrode 103. By providing the first discontinuous structure 172 surrounding the first overlapping region 106, the transverse shear wave in the first overlapping region 106 can be reflected, and the energy can be concentrated in the longitudinal wave in the first overlapping region 106, thereby suppressing the transverse parasitic mode (i.e., suppressing the parasitic resonance) and achieving the effect of increasing the Q value.

[0087] An embodiment of the present invention provides an acoustic wave device comprising the bulk acoustic wave resonator structure according to the above embodiment, including but not limited to a filter, a duplexer, a multiplexer, etc.

[0088] In the embodiments of the present invention, for a specific description of the bulk acoustic wave resonator structure in the acoustic wave device, reference can be made to the bulk acoustic wave resonator structure in the above-mentioned embodiments, and the description will not be repeated here.

[0089] 21 shows an exemplary flow chart of a method for manufacturing a bulk acoustic wave resonator structure according to an embodiment of the present invention. Based on the above bulk acoustic wave resonator structure, an embodiment of the present invention provides a method for manufacturing a bulk acoustic wave resonator structure, the method includes the following steps:

[0090] In S10, a substrate is provided and a sacrificial layer is formed on a surface of the substrate.

[0091] In S20, a first electrode and a piezoelectric layer are formed overlying the sacrificial layer.

[0092] In S30, a protruding material layer is formed on a side of the piezoelectric layer relatively away from the substrate.

[0093] In S40, a second electrode is formed covering the protruding material layer, and the effective area of ​​the resonance region is the first overlapping region.

[0094] In S50, the second electrode and the protruding material layer at the edge of the first overlap region are etched to form spaced apart first protruding structures and first discontinuous structures, the first protruding structures and the first discontinuous structures forming a first surrounding structure surrounding the first overlap region, and one end of each first protruding structure adjacent to the first overlap region is covered by the second electrode.

[0095] In S60, at least one etching hole is formed, and the sacrificial layer is removed through the etching hole to form a reflective structure.

[0096] For the constituent materials of the substrate, the first electrode, the piezoelectric layer, the second electrode, and the reflecting structure, reference can be made to the relevant descriptions of the above embodiments of the bulk acoustic wave resonator structure, and the description will not be repeated here.

[0097] 22a to 22d show schematic cross-sectional views corresponding to the process of the method for manufacturing a bulk acoustic wave resonator structure according to one exemplary embodiment. Referring to FIG. 22a, step S10 is performed. In some embodiments, a sacrificial material is deposited on the substrate 101, and the sacrificial material is etched to form a sacrificial layer 102a. Exemplarily, the material of the sacrificial layer 102a includes, but is not limited to, phosphorus silicate glass (PSG) or silicon dioxide. As an example, the material of the sacrificial layer 102a is silicon dioxide, and the sacrificial layer 102a can be formed on the first surface of the substrate 101 by a chemical vapor deposition process using silane (SiH4) and oxygen (O2) as reactive gases.

[0098] As shown in Fig. 22a, a sacrificial layer 102a can be formed on a substrate 101, and the sacrificial layer 102a protrudes from an upper surface of the substrate 101. The sacrificial layer 102a can be removed in a subsequent process to form a protruding cavity-type reflective structure 102 (see Fig. 22d).

[0099] Referring to Fig. 22b, step S20 is performed. A first electrode material is formed to cover the sacrificial layer 102a and the substrate 101, and the first electrode material is patterned to form a first electrode 103. As shown in Fig. 22b, a piezoelectric layer 104 is formed to cover the first electrode 103.

[0100] Before depositing the first electrode 103, a seed layer may be deposited to improve the crystal axis orientation of the material of the lower electrode, so that the crystal lattice is closer to the piezoelectric layer and the lattice defects of the subsequently deposited piezoelectric layer can be reduced, while the seed layer can also function as an etching stop layer for the first electrode 103. Exemplarily, the constituent material of the seed layer is the same as the constituent material of the piezoelectric layer 104.

[0101] Referring to FIG. 22c, steps S30 to S40 are performed. A sacrificial material is deposited on the side of the piezoelectric layer 104 that is relatively far from the substrate 101 to form a protruding material layer 107a. A second electrode material is formed to cover the protruding material layer 107a and the piezoelectric layer 104, and the second electrode material is patterned to form a second electrode 105. Exemplarily, the constituent material of the protruding material layer 107a is the same as the constituent material of the sacrificial layer 102a. Note that, in one example, the protruding material layer 107a can be removed in a subsequent process to form an air-type first protruding structure 171. In another example, the protruding material layer 107a can be formed without being removed in a subsequent process to form the first protruding structure 171 (see FIG. 22d).

[0102] Referring to Fig. 22d, step S50 is performed. In practical application, the effective area of ​​the resonance region is the first overlapping region 106. Note that in Fig. 22d, the first discontinuous structure 172 is not shown. Referring to Fig. 1 and Fig. 3, the second electrode 105 and the protruding material layer 107a at the edge of the first overlapping region 106 are etched to form the first protruding structures 171 and the first discontinuous structures 172 arranged at intervals, where the first protruding structures 171 and the first discontinuous structures 172 form the first surrounding structure 107 surrounding the first overlapping region 106, and one end of each first protruding structure 171 adjacent to the first overlapping region 106 is covered by the second electrode 105.

[0103] Referring to Fig. 22d, step S60 is performed. At least one etching hole is formed, and the sacrificial layer 102a is removed through the etching hole to form the reflecting structure 102. In one embodiment, the etching hole is used to release an etchant to remove the sacrificial layer 102a. Here, the etching hole can penetrate the piezoelectric layer 104 and the sacrificial layer 102a until the surface of the substrate 101 is exposed. In another embodiment, the etching hole can only penetrate the piezoelectric layer 104 until the surface of the sacrificial layer 102a is exposed, that is, the etching hole does not need to penetrate the sacrificial layer 102a.

[0104] For example, the sacrificial layer 102a can be removed by selecting an appropriate etching agent and injecting the etching agent into the etching holes so that the etching agent comes into contact with the exposed sacrificial layer 102a and chemically reacts to generate gaseous products.

[0105] Specifically, when the sacrificial layer 102a is made of silicon dioxide, a dry etching process can be adopted to remove the sacrificial layer 102a by selecting hydrogen fluoride (HF) as an etchant. When hydrogen fluoride reacts with the sacrificial layer 102a exposed through the etching holes, gaseous silicon fluoride (SiF4) and gaseous water are generated.

[0106] In some embodiments, the method further comprises thinning the second electrode 105. The thinning can provide additional frequency modulation for the bulk acoustic wave resonant structure.

[0107] In the embodiment of the present invention, the first protruding structure 171 surrounding the first overlapping region 106 can increase the distance between the first electrode 103 and the second electrode 105 at the edge of the first overlapping region 106, thereby reducing the electric field intensity at the edge of the first overlapping region 106. The reduced electric field intensity reduces the electric displacement and the effect of the piezoelectric resonance, thereby reducing the parasitic resonance at the edge of the first overlapping region 106, and the propagation of the parasitic resonance to the first overlapping region 106 can be reduced, thereby increasing the quality factor (Q value) of the bulk acoustic wave resonator structure. Furthermore, the first discontinuous structure 172 surrounding the first overlapping region 106 can reflect the transverse shear wave in the first overlapping region 106 and concentrate the energy into the longitudinal wave in the first overlapping region 106, thereby achieving the effect of suppressing the transverse parasitic mode (i.e., suppressing the parasitic resonance) and increasing the Q value.

[0108] Based on the above bulk acoustic wave resonator structure, an embodiment of the present invention provides another method for manufacturing a bulk acoustic wave resonator structure, the method includes the following steps.

[0109] In step 1, a substrate is provided and a sacrificial layer is formed on a surface of the substrate.

[0110] In step 2, a first electrode is formed covering the sacrificial layer.

[0111] In step 3, a protruding material layer is formed on the first electrode.

[0112] In step 4, a piezoelectric layer is formed covering the protruding material layer and the first electrode.

[0113] In step 5, a second electrode is formed to cover the piezoelectric layer, and the effective area of ​​the resonance region is the first overlapping area.

[0114] In step 6, the second electrode, the piezoelectric layer and the protruding material layer at the edge of the first overlapping region are etched to form spaced apart first protruding structures and first discontinuous structures, the first protruding structures and the first discontinuous structures forming a first surrounding structure surrounding the first overlapping region, and one end of each first protruding structure adjacent to the first overlapping region is covered by the first electrode.

[0115] In step 7, at least one etching hole is formed, and the sacrificial layer is removed through the etching hole to form a reflective structure.

[0116] In addition, for specific processes for forming the substrate 101, the reflecting structure 102, the first electrode 103, the piezoelectric layer 104 and the second electrode 105 in steps 1 to 7, reference can be made to the explanation in the illustrative flowchart of steps S10 to S60 above.

[0117] 23a-23d show schematic cross-sectional views corresponding to the process of the method for manufacturing a bulk acoustic wave resonator structure according to an embodiment of the present invention. Referring to FIG. 23a, step 1 is carried out. In some embodiments, a sacrificial material is deposited on a substrate 101, the sacrificial material is etched to form a sacrificial layer 102a, and a first groove H1 is formed in the sacrificial layer 102a by etching. As shown in FIG. 23a, the sacrificial layer 102a can be formed on the substrate 101, and the sacrificial layer 102a protrudes from the upper surface of the substrate 101. The sacrificial layer 102a can be removed in a subsequent process to form a protruding cavity-type reflecting structure 102 (see FIG. 23d).

[0118] Referring to FIG. 23b, step 2 is performed. A first electrode material is deposited, and the first electrode material is patterned to form the first electrode 103. A second groove H2 is formed in the first electrode 103 by etching. The etching method includes, but is not limited to, dry etching and wet etching. As shown in FIG. 23b, in one example, the second groove H2 is formed in the first electrode 103 by etching. In another example, due to the morphological characteristics of the first groove H1 in the sacrificial layer 102a, the second groove H2 is formed simultaneously with forming the first electrode 103 by deposition.

[0119] Referring to FIG. 23c, step 3 is performed. A sacrificial material is deposited in the second groove H2, and the sacrificial material is etched to form a protruding material layer 107a. Exemplarily, the constituent material of the protruding material layer 107a is the same as the constituent material of the sacrificial layer 102a. In one example, the protruding material layer 107a can be removed in a subsequent process to form a first protruding structure 171 (not shown) made of air. In another example, the protruding material layer 107a can be not removed in a subsequent process to form a first protruding structure 171 made of a sacrificial material (e.g., silicon dioxide) (see FIG. 23d).

[0120] 23c, steps 4 and 5 are performed. A piezoelectric layer 104 is formed to cover the protruding material layer 107a and the first electrode 103. A second electrode material is formed to cover the piezoelectric layer 104, and the second electrode material is patterned to form a second electrode 105.

[0121] Referring to Fig. 23d, step 6 is carried out. In practical application, the effective area of ​​the resonance region is the first overlapping region 106. Note that in Fig. 23d, the first discontinuous structure 172 is not shown, and referring to Fig. 1 and Fig. 10, the second electrode 105, the piezoelectric layer 104 and the protruding material layer 107a at the edge of the first overlapping region 106 are etched to form the first protruding structures 171 and the first discontinuous structures 172 arranged at intervals, where the first protruding structures 171 and the first discontinuous structures 172 form the first surrounding structure 107 surrounding the first overlapping region 106, and one end of each first protruding structure 171 adjacent to the first overlapping region 106 is covered by the first electrode 103.

[0122] Referring to Fig. 23d, step 7 is performed. At least one etching hole is formed, and the sacrificial layer 102a is removed through the etching hole to form the reflecting structure 102. The specific process of step 7 can refer to the description of step S60 in the exemplary flow chart shown in Fig. 21, and will not be described again here.

[0123] In the embodiment of the present invention, the first protruding structure 171 surrounding the first overlapping region 106 can increase the distance between the first electrode 103 and the second electrode 105 at the edge of the first overlapping region 106, thereby reducing the electric field intensity at the edge of the first overlapping region 106. The reduced electric field intensity reduces the electric displacement and the effect of the piezoelectric resonance, thereby reducing the parasitic resonance at the edge of the first overlapping region 106, and the propagation of the parasitic resonance to the first overlapping region 106 can be reduced, thereby increasing the quality factor (Q value) of the bulk acoustic wave resonator structure. Furthermore, the first discontinuous structure 172 surrounding the first overlapping region 106 can reflect the transverse shear wave in the first overlapping region 106 and concentrate the energy into the longitudinal wave in the first overlapping region 106, thereby achieving the effect of suppressing the transverse parasitic mode (i.e., suppressing the parasitic resonance) and increasing the Q value.

[0124] Based on the above bulk acoustic wave resonator structure, an embodiment of the present invention provides yet another method for manufacturing a bulk acoustic wave resonator structure, the method including the following steps.

[0125] In step 1, a substrate is provided and a sacrificial layer is formed on a surface of the substrate.

[0126] In step 2, a first electrode and a piezoelectric layer are formed overlying a sacrificial layer.

[0127] In step 3, a spaced apart sacrificial material structure and a first discontinuous structure are formed on a side of the piezoelectric layer relatively remote from the substrate.

[0128] In step 4, a second electrode is formed covering the sacrificial material structure and the first discontinuous structure, and the active area of ​​the resonance region is the first overlapping region.

[0129] In step 5, at least one etching hole is formed, and the sacrificial material structure and the sacrificial layer are removed through the etching hole to form a first protruding structure and a reflective structure, respectively, wherein the first protruding structure and the first discontinuous structure form a first surrounding structure surrounding the first overlapping region, and one end of each first protruding structure adjacent to the first overlapping region is covered by the second electrode.

[0130] In addition, in steps 1 to 5, for the specific process of forming the substrate 101, the reflecting structure 102, the first electrode 103, the piezoelectric layer 104 and the second electrode 105, reference can be made to the explanation in the exemplary flowchart of steps S10 to S60 above.

[0131] Referring to Fig. 22a, step 1 is performed. In some embodiments, a sacrificial material is deposited on a substrate 101, and the sacrificial material is etched to form a sacrificial layer 102a. As shown in Fig. 22a, the sacrificial layer 102a can be formed on the substrate 101, and the sacrificial layer 102a protrudes from the top surface of the substrate 101. The sacrificial layer 102a can be removed in a subsequent process to form a protruding cavity-type reflective structure 102.

[0132] 22b, step 2 is performed: depositing a first electrode material and patterning the first electrode material to form a first electrode 103; forming a piezoelectric layer 104 covering the first electrode 103;

[0133] Step 3 is performed. A sacrificial material structure and a first discontinuous structure 172 arranged at intervals are formed on the side of the piezoelectric layer 104 relatively away from the substrate 101 (see FIG. 7). In one example, the sacrificial material structure can be removed in a subsequent process to form an air-type first protruding structure 171. In another example, the protruding material layer 107a can be formed without being removed in a subsequent process to form the first protruding structure 171 (see FIG. 7). By forming the intermittent first protruding structure 171, an etching process for forming the first discontinuous structure 172 can be eliminated. The material of the intermittent first protruding structure 171 may be air, the protrusions are air, and the upper part of the first discontinuous structure 172 is the material of the upper electrode (second electrode 105).

[0134] Step 4 is performed: forming a second electrode material covering the sacrificial material structure and the first discontinuous structure 172, and patterning the second electrode material to form the second electrode 105. In practical application, the effective area of ​​the resonance region is the first overlapping region 106.

[0135] Step 5 is carried out. At least one etching hole is formed, and the sacrificial material structure and the sacrificial layer 102a are removed through the etching hole to form a first protruding structure 171 and a reflective structure 102, respectively, the first protruding structure 171 and the first discontinuous structure 172 form a first surrounding structure 107 surrounding the first overlapping region 106, and one end of each first protruding structure 171 adjacent to the first overlapping region 106 is covered by the second electrode 105. The specific process of removal through the etching hole in step 5 can refer to the description of step S60 in the exemplary flowchart shown in FIG. 21, and will not be described again here.

[0136] In the embodiment of the present invention, the first protruding structure 171 surrounding the first overlapping region 106 can increase the distance between the first electrode 103 and the second electrode 105 at the edge of the first overlapping region 106, reduce the parasitic resonance at the edge of the first overlapping region 106, and reduce the propagation of the parasitic resonance to the first overlapping region 106, thereby improving the quality factor (Q value) of the bulk acoustic wave resonator structure. The first discontinuous structure 172 surrounding the first overlapping region 106 can reflect the transverse shear wave in the first overlapping region 106, thereby suppressing the transverse parasitic mode (i.e., suppressing the parasitic resonance) and achieving the effect of improving the Q value. In addition, by forming the intermittent first protruding structure 171, the etching process for forming the first discontinuous structure 172 can be eliminated, thereby reducing the process steps, simplifying the manufacturing process, and saving costs.

[0137] According to a simulation test, Fig. 24 shows the Smith chart test results of the bulk acoustic wave resonator structure shown in Fig. 1 and the bulk acoustic wave resonator structure with a normal cantilever structure. As shown in Fig. 24, the Smith circle of the bulk acoustic wave resonator structure shown in Fig. 1 is smoother, so that the embodiment of the present invention, for example, the bulk acoustic wave resonator structure shown in Fig. 1, has better device performance than the bulk acoustic wave resonator structure with a normal cantilever structure.

[0138] According to a simulation test, FIG. 25 shows the Smith chart test results of the bulk acoustic wave resonator structure shown in FIG. 20 and the normal bulk acoustic wave resonator structure, respectively. The normal bulk acoustic wave resonator structure means a bulk acoustic wave resonator structure without a cantilever structure, a frame structure and a groove. As shown in FIG. 25, the Smith circle of the bulk acoustic wave resonator structure shown in FIG. 20 is smoother, so compared with the normal bulk acoustic wave resonator structure, the embodiment of the present invention, for example, the bulk acoustic wave resonator structure shown in FIG. 20, has better device performance.

[0139] It should be understood that "one embodiment" or "some embodiments" referred to throughout this specification means that a particular feature, structure or characteristic associated with an embodiment is included in at least one embodiment of the present invention. Thus, "in one embodiment" or "in some embodiments" in this specification do not necessarily refer to the same embodiment. Moreover, these particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments. It should be understood that in each embodiment of the present invention, the numbers of each process described above do not mean the order of execution, and the execution order of each process should be determined by its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiment of the present invention. The above numbers of the embodiments of the present invention are merely for convenience of explanation, and do not represent the superiority or inferiority of the embodiments.

[0140] The above content is only a specific embodiment of the present invention, and the protection scope of the present invention is not limited thereto. Any modifications or replacements that can be easily thought of by those skilled in the art within the technical scope disclosed in the present invention should be included in the protection scope of the present invention.

Claims

1. 1. A bulk acoustic wave resonator structure, comprising: A substrate; a reflection structure, a first electrode, a piezoelectric layer, and a second electrode sequentially arranged on the substrate, the reflection structure, the first electrode, the piezoelectric layer, and the second electrode, the effective area of ​​the resonance region being a first overlap area; a first surrounding structure surrounding the first overlap region, the first surrounding structure including a first protruding structure and a first discontinuous structure arranged at a distance from each other; The bulk acoustic wave resonator structure, wherein the first protruding structure is arranged between the piezoelectric layer and the first electrode and / or between the piezoelectric layer and the second electrode, and one end of each of the first protruding structures adjacent to the first overlap region is covered by the first electrode and / or the second electrode.

2. When the first protruding structure is disposed only between the piezoelectric layer and the second electrode, the bulk acoustic wave resonator structure further comprises a second surrounding structure surrounding the first surrounding structure; the second surrounding structure partially covers a sidewall of the piezoelectric layer relatively remote from the reflecting structure; 2. The bulk acoustic wave resonator structure of claim 1.

3. The second surrounding structure and the first protruding structure are made of the same material, and the second surrounding structure and the first protruding structure are connected to each other to form an integrated structure.

3. A bulk acoustic wave resonator structure as claimed in claim 2.

4. the second surrounding structure includes a second protruding structure and a second discontinuous structure arranged at an interval, the first discontinuous structure and the second discontinuous structure are gaps, the second protruding structure and the first protruding structure are made of the same material, and the second protruding structure and the first protruding structure are connected to form an integrated structure; 3. A bulk acoustic wave resonator structure as claimed in claim 2.

5. When the first protruding structures are disposed only between the piezoelectric layer and the second electrode, one end of each of the first protruding structures adjacent to the first overlapping region and the other end remote from the first overlapping region are both covered by the second electrode; each of the first protruding structures includes a top portion and a bottom portion opposed along a direction perpendicular to the substrate, the top portion being in direct contact with the second electrode, and the bottom portion being in direct contact with the piezoelectric layer; 2. The bulk acoustic wave resonator structure of claim 1.

6. When the first protruding structures are disposed only between the piezoelectric layer and the first electrode, one end of each of the first protruding structures adjacent to the first overlapping region and the other end remote from the first overlapping region are both covered by the first electrode; each of the first protruding structures includes a top portion and a bottom portion opposed along a direction perpendicular to the substrate, the top portion being in direct contact with the piezoelectric layer, and the bottom portion being in direct contact with the first electrode; 2. The bulk acoustic wave resonator structure of claim 1.

7. the first protruding structure includes a first sub-structure and a second sub-structure; the first substructures are disposed only between the piezoelectric layer and the second electrode, and one end of each of the first substructures adjacent to the first overlapping region and the other end remote from the first overlapping region are both covered by the second electrode; the second substructures are disposed only between the piezoelectric layer and the first electrode, and one end of each of the second substructures adjacent to the first overlapping region and the other end remote from the first overlapping region are both covered by the first electrode; an orthogonal projection of the first substructure on the substrate at least partially overlaps with an orthogonal projection of the second substructure on the substrate; 2. The bulk acoustic wave resonator structure of claim 1.

8. a distance in a first direction between one end of the first protruding structure adjacent to the first overlapping region and an edge of the first overlapping region is 0 to 10 μm, and the first direction is a direction from the edge of the first overlapping region toward the center of the first overlapping region; 2. The bulk acoustic wave resonator structure of claim 1.

9. the bulk acoustic wave resonator structure further comprises a first electrode lead and a second electrode lead, the first electrode lead being connected to the first electrode and the second electrode lead being connected to the second electrode; orthogonal projections of the first electrode lead and the second electrode lead on the substrate are located in a region other than the first overlap region; an orthogonal projection of the first discontinuous structure on the substrate falls in an area other than an orthogonal projection of the first electrode lead and the second electrode lead on the substrate; 2. The bulk acoustic wave resonator structure of claim 1.

10. The bulk acoustic wave resonator structure further comprises a frequency modulation layer, the frequency modulation layer being disposed on the second electrode; the first surrounding structure is disposed between the frequency modulation layer and the second electrode.

2. The bulk acoustic wave resonator structure of claim 1.

11. the bulk acoustic wave resonator structure further comprises a seed layer, the seed layer being disposed between the first electrode and the substrate; the first surrounding structure is disposed between the seed layer and the first electrode.

2. The bulk acoustic wave resonator structure of claim 1.

12. the first discontinuous structure is a groove; the groove penetrates at least one of the second electrode, the first protruding structure, the piezoelectric layer, and the first electrode along a direction perpendicular to the substrate; 2. The bulk acoustic wave resonator structure of claim 1.

13. the bulk acoustic wave resonator structure further comprises a stripe structure disposed on and connected to the second electrode; An orthogonal projection of the stripe structure on the substrate falls in an area other than the first overlapping area, and the stripe structure is arranged at intervals surrounding the first overlapping area.

2. The bulk acoustic wave resonator structure of claim 1.

14. An acoustic wave device comprising a bulk acoustic wave resonator structure according to any one of claims 1 to 13.

15. 1. A method for manufacturing a bulk acoustic wave resonator structure, comprising: Providing a substrate and forming a sacrificial layer on a surface of the substrate; forming a first electrode and a piezoelectric layer overlying the sacrificial layer; forming a protruding material layer on a side of the piezoelectric layer relatively remote from the substrate; forming a second electrode covering the protruding material layer, where an effective area of ​​a resonance region is a first overlapping region; Etching the second electrode and the protruding material layer at edges of the first overlapping region to form spaced apart first protruding structures and first discontinuous structures, the first protruding structures and the first discontinuous structures forming a first surrounding structure surrounding the first overlapping region, and one end of each of the first protruding structures adjacent to the first overlapping region being covered by the second electrode; forming at least one etching hole and removing the sacrificial layer through the etching hole to form a reflecting structure.

16. 1. A method for manufacturing a bulk acoustic wave resonator structure, comprising: Providing a substrate and forming a sacrificial layer on a surface of the substrate; forming a first electrode overlying the sacrificial layer; forming a protruding material layer on the first electrode; forming a piezoelectric layer overlying the protruding material layer and the first electrode; forming a second electrode covering the piezoelectric layer, the effective area of ​​the resonance region being a first overlapping area; etching the second electrode, the piezoelectric layer and the protruding material layer at edges of the first overlapping region to form spaced apart first protruding structures and first discontinuous structures, the first protruding structures and the first discontinuous structures forming a first surrounding structure surrounding the first overlapping region, and one end of each of the first protruding structures adjacent to the first overlapping region being covered by the first electrode; forming at least one etching hole and removing the sacrificial layer through the etching hole to form a reflecting structure.

17. 1. A method for manufacturing a bulk acoustic wave resonator structure, comprising: Providing a substrate and forming a sacrificial layer on a surface of the substrate; forming a first electrode and a piezoelectric layer overlying the sacrificial layer; forming a spaced apart sacrificial material structure and a first discontinuity structure on a side of the piezoelectric layer relatively remote from the substrate; forming a second electrode covering the sacrificial material structure and the first discontinuous structure, wherein an active area of ​​a resonance region is a first overlap region; forming at least one etching hole; and removing a sacrificial material structure and the sacrificial layer through the etching hole to form a first protruding structure and a reflecting structure, respectively, wherein the first protruding structure and the first discontinuous structure form a first surrounding structure surrounding the first overlapping region, and one end of each of the first protruding structures adjacent to the first overlapping region is covered by the second electrode.

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