Bulk acoustic wave resonator, method of manufacturing bulk acoustic wave resonator, filter, and electronic device

Abstract

The present application relates to a bulk acoustic wave resonator and a manufacturing method thereof, the resonator comprising: a substrate; an acoustic mirror; a bottom electrode; a top electrode; and a piezoelectric layer arranged between the bottom electrode and the top electrode, wherein: the piezoelectric layer is a flat piezoelectric layer; a support layer is arranged between the substrate and the piezoelectric layer, the piezoelectric layer is a flat piezoelectric layer, the piezoelectric layer and the substrate are arranged apart from each other and substantially parallel to each other in a thickness direction of the resonator, and a high linearity material layer is arranged outside the non-electrode connecting end of the bottom electrode in a horizontal direction. The present application also relates to a filter and an electronic device.

Description

Technical Field

[0001] Embodiments of the present invention relate to the semiconductor field, and more particularly to a bulk acoustic wave resonator and a method for manufacturing the same, a filter having the resonator, and an electronic device. Background Technology

[0002] Electronic components, as fundamental elements of electronic devices, are widely used in mobile phones, automobiles, and home appliances. Furthermore, future world-changing technologies such as artificial intelligence, the Internet of Things, and 5G communications still rely on electronic components as their foundation.

[0003] Film Bulk Acoustic Resonators (FBARs, also known as BAWs) are playing a vital role in the communications field as an important member of piezoelectric devices. In particular, FBAR filters are gaining an increasingly larger market share in the radio frequency (RF) filter sector. FBARs possess excellent characteristics such as small size, high resonant frequency, high quality factor, large power capacity, and good roll-off effect. Their filters are gradually replacing traditional surface acoustic wave (SAW) filters and ceramic filters, playing a significant role in the RF field of wireless communications. Their high sensitivity advantage can also be applied to sensing fields such as biology, physics, and medicine.

[0004] The main structure of a thin-film bulk acoustic resonator (FBAR) is a "sandwich" structure consisting of a bottom electrode and a piezoelectric thin film or a piezoelectric layer and a top electrode, i.e., a piezoelectric material sandwiched between two metal electrode layers. By inputting a sinusoidal signal between the two electrodes, the FBAR uses the inverse piezoelectric effect to convert the input electrical signal into mechanical resonance, and then uses the piezoelectric effect to convert the mechanical resonance back into an electrical signal output.

[0005] In a bulk acoustic resonator with a known structure, an edge parasitic electric field is generated between the non-electrode connection of the bottom electrode and the top electrode at the edge of the effective region of the resonator. This edge parasitic electric field generates an unwanted nonlinear current, thereby reducing the linearity of the resonator.

[0006] For filters that include bulk acoustic resonators, there is also a need to improve the linearity of the filter. Summary of the Invention

[0007] The present invention is proposed to alleviate or solve at least one of the above-mentioned problems in the prior art.

[0008] According to one aspect of an embodiment of the present invention, a bulk acoustic resonator is provided, comprising:

[0009] Base;

[0010] Acoustic mirror;

[0011] Bottom electrode;

[0012] Top electrode; and

[0013] A piezoelectric layer is disposed between the bottom electrode and the top electrode.

[0014] in:

[0015] The piezoelectric layer is a flat piezoelectric layer, and a support layer is provided between the substrate and the piezoelectric layer. The piezoelectric layer and the substrate are spaced apart from each other in the thickness direction of the resonator and are generally parallel to each other.

[0016] The non-electrode connection end of the bottom electrode is provided with a high linearity material layer on its outer side in the horizontal direction.

[0017] The present invention relates to a method for manufacturing a bulk acoustic wave resonator, the bulk acoustic wave resonator comprising a substrate, an acoustic mirror, a bottom electrode, a top electrode, and a piezoelectric layer, wherein the piezoelectric layer is disposed between the bottom electrode and the top electrode and is a flat piezoelectric layer, the method comprising the steps of:

[0018] A support layer is provided between the substrate and the piezoelectric layer, such that the piezoelectric layer and the substrate are spaced apart from each other and are generally parallel to each other in the thickness direction of the resonator.

[0019] A high linearity material layer is disposed on the outer side of the non-electrode connection end of the bottom electrode in the horizontal direction.

[0020] Embodiments of the present invention also relate to a filter, including the aforementioned bulk acoustic resonator.

[0021] Embodiments of the present invention also relate to an electronic device, including the filter or the resonator described above. Attached Figure Description

[0022] The following description and accompanying drawings will better aid in understanding these and other features and advantages of the various embodiments disclosed herein, wherein the same reference numerals in the drawings always denote the same parts, wherein:

[0023] Figure 1 A schematic cross-sectional view of a bulk acoustic resonator according to an exemplary embodiment of the present invention;

[0024] Figure 1A for Figure 1 An enlarged schematic diagram of part A in the diagram;

[0025] Figure 2 A schematic cross-sectional view of a bulk acoustic resonator according to another exemplary embodiment of the present invention;

[0026] Figure 3 A schematic cross-sectional view of a bulk acoustic resonator according to yet another exemplary embodiment of the present invention;

[0027] Figure 4A A schematic cross-sectional view of a bulk acoustic resonator according to another exemplary embodiment of the present invention;

[0028] Figure 4B A schematic cross-sectional view of a bulk acoustic resonator according to yet another exemplary embodiment of the present invention;

[0029] Figure 5 A schematic cross-sectional view of a bulk acoustic resonator according to another exemplary embodiment of the present invention;

[0030] Figures 6A-6K For example Figure 1 The diagram shows a cross-sectional view of the fabrication process of a bulk acoustic resonator. Detailed Implementation

[0031] The technical solution of the present invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings. In this specification, the same or similar reference numerals indicate the same or similar components. The following description of the embodiments of the present invention with reference to the accompanying drawings is intended to explain the overall inventive concept of the present invention and should not be construed as a limitation thereof. These are only some embodiments of the invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0032] In this invention, the reference numerals are explained as follows:

[0033] 101: Substrate, with optional materials including single-crystal silicon, gallium nitride, gallium arsenide, sapphire, quartz, silicon carbide, diamond, etc.

[0034] 102: Auxiliary substrate, with optional materials including single-crystal silicon, gallium nitride, gallium arsenide, sapphire, quartz, silicon carbide, diamond, etc.

[0035] 103: Acoustic mirror, which can be a cavity, or it can be a Bragg reflector layer or other equivalent forms. The embodiment shown in this invention uses a cavity.

[0036] 104: Sacrificial material layer, which can be silicon dioxide, doped silicon dioxide, polycrystalline silicon, amorphous silicon, etc.

[0037] 105: Support layer, made of highly linear materials, including but not limited to NEBSG, SiO2, doped SiO2, ALN or doped ALN, GaAS, GaN, SiC, SiN, etc.

[0038] 107: Bottom electrode. The bottom electrode material can be: gold (Au), tungsten (W), molybdenum (Mo), platinum (Pt), ruthenium (Ru), iridium (Ir), titanium tungsten (TiW), aluminum (Al), titanium (Ti), osmium (Os), magnesium (Mg), gold (Au), tungsten (W), molybdenum (Mo), platinum (Pt), ruthenium (Ru), iridium (Ir), germanium (Ge), copper (Cu), aluminum (Al), chromium (Cr), arsenic-doped gold, and similar metals, as well as composites or alloys of the above metals.

[0039] 109: The piezoelectric layer can be a single-crystal piezoelectric material, such as single-crystal aluminum nitride, single-crystal gallium nitride, single-crystal lithium niobate, single-crystal potassium niobate, single-crystal quartz film, or single-crystal lithium tantalate, etc. It can also be a polycrystalline piezoelectric material (as opposed to single-crystal, a non-single-crystal material), such as polycrystalline aluminum nitride, zinc oxide, PZT, etc. It can also be a rare-earth element doped material containing a certain atomic ratio of the above materials, for example... It can be doped aluminum nitride, which contains at least one rare earth element, such as scandium (Sc), yttrium (Y), magnesium (Mg), titanium (Ti), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), etc.

[0040] 111: Top electrode, which can be: gold (Au), tungsten (W), molybdenum (Mo), platinum (Pt), ruthenium (Ru), iridium (Ir), titanium-tungsten (TiW), aluminum (Al), titanium (Ti), osmium (Os), magnesium (Mg), gold (Au), tungsten (W), molybdenum (Mo), platinum (Pt), ruthenium (Ru), iridium (Ir), germanium (Ge), copper (Cu), aluminum (Al), chromium (Cr), arsenic-doped gold, and similar metals, as well as composites or alloys of the above metals. The top electrode and bottom electrode materials are generally the same, but they can also be different.

[0041] 112: A connection hole passes through the piezoelectric layer, and the bottom electrode lead-out portion 113 is electrically connected to the bottom electrode via this connection hole.

[0042] 113: Bottom electrode lead-out section, which can be fabricated simultaneously with the top electrode. The material can be molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or a composite of the above metals or their alloys.

[0043] 115: Bridge structure, which defines the gap.

[0044] Figure 1 This is a schematic cross-sectional view of a bulk acoustic resonator according to an exemplary embodiment of the present invention. Figure 1A for Figure 1 An enlarged schematic diagram of part A in the image. Figure 1In the illustrated embodiment, the right edge of the bottom electrode 107 (i.e., the non-electrode connection end of the bottom electrode) is covered by the support layer 105, such as... Figure 1 As shown, the non-electrode connection end of the bottom electrode 107 is disposed between the piezoelectric layer 109 and the support layer 105 in the thickness direction of the resonator, and the outer edge of the support layer 105 is located outside the non-electrode connection end of the bottom electrode 107 in the horizontal direction.

[0045] like Figure 1 As shown, the piezoelectric layer 109 is a flat piezoelectric layer, meaning that the piezoelectric layer does not have any steps or bends. As mentioned earlier, the piezoelectric layer 109 can be a monocrystalline piezoelectric layer or a flat polycrystalline piezoelectric layer.

[0046] See also Figure 1 As can be seen, the support layer 105 is disposed between the piezoelectric layer 109 and the substrate 101. The piezoelectric layer 109 and the substrate 101 are spaced apart from each other in the thickness direction of the resonator and are generally parallel to each other.

[0047] like Figure 1 The acoustic mirror 103 of the bulk acoustic resonator shown is an acoustic mirror cavity. It can be seen that... Figure 1 In the middle, the support layer 105 serves as the boundary of the acoustic mirror cavity in the lateral direction.

[0048] As those skilled in the art will understand, acoustic mirrors may not be in the form of cavities; for example, they may be Bragg reflectors. In this case, the Bragg reflector may also be positioned as follows: Figure 1 The location within the cavity is shown.

[0049] exist Figure 1 In the illustrated embodiment, the upper boundary of the acoustic mirror cavity is the lower surface of the bottom electrode (in this invention, the lower surface of the bottom electrode includes the region corresponding to the acoustic mirror cavity, and the lower surface of the bottom electrode is covered by both other layers and no other layers), while the lower boundary is the upper surface of the substrate (in this invention, the upper surface of the substrate includes the region corresponding to the acoustic mirror cavity, and the upper surface of the substrate is covered by both other layers and no other layers). However, the invention is not limited thereto; see also the following references. Figure 5 As can be seen, the acoustic mirror cavity is a cavity recessed into the support layer. In other words, the lower side or lower boundary of the acoustic mirror cavity is defined by the support layer 105.

[0050] exist Figure 1 In the middle, the electrode connection terminal of the bottom electrode 107 ( Figure 1 The left side of the resonator is covered by the support layer 105 and is located between the piezoelectric layer 109 and the support layer 105 in the thickness direction of the resonator, and the outer edge of the support layer 105 ( Figure 1The left side of the piezoelectric layer 109 is located outside the electrode connection end of the bottom electrode 107 in the horizontal direction. A through-hole 112 is provided in the piezoelectric layer 109 (see [reference]). Figure 6I See also Figure 1 The resonator also includes an electrode lead-out portion 113 that is electrically connected to the electrode connection end of the bottom electrode 107 via a through hole. A portion of the electrode lead-out portion 113 is located on the upper surface of the piezoelectric layer 109 and is arranged in the same layer as the top electrode 111.

[0051] It should be noted that, in one embodiment of the present invention, the electrode connection end of the bottom electrode may not be covered by the support layer 105 (i.e., the electrode connection end of the bottom electrode may be located inside the boundary of the support layer, in which case power can be supplied to the bottom electrode 107 via the electrode lead-out portion 113); in another embodiment of the present invention, the electrode connection end of the bottom electrode 107 may be covered by the support layer, however, the electrode connection end may extend beyond the outer boundary of the support layer or be flush with the outer boundary. These are all within the scope of protection of the present invention.

[0052] exist Figure 1 In the middle, the two ends of the bottom electrode 107 are placed inside the support layer 105. The edge parasitic electric field between the right edge of the bottom electrode 107 (i.e., the non-electrode connection end of the bottom electrode) and the right end of the top electrode 111 will pass through the support layer 105 (see Figure 1A The bottom electrode 107 is embedded in the support layer 105. If the material of the support layer 105 is not chosen appropriately, and its linearity is low (e.g., silicon), the nonlinearity of the resonator and the filter using the resonator will be high. If a high-linearity material is chosen for the support layer 105, the nonlinearity of the resonator and the filter can be reduced. It is important to emphasize that since most of the edge parasitic electric field is concentrated on the right edge of the bottom electrode 107, and the edge parasitic electric field intensity is high, and the right edge of the bottom electrode is completely wrapped by the support layer, the linearity of the support layer material that plays this role is very critical.

[0053] exist Figure 1 In the example shown, the support layer is made of a highly linear material, such as NEBSG (non-etchable borosilicate glass), SiO2, doped SiO2, ALN or doped ALN, GaAs, GaN, SiC, SiN, etc. In this invention, a highly linear material refers to a material with linearity higher than that of silicon. When an electric field passes through a material, the material will produce an electrical response (such as current). If the frequency of the material's electrical response is the same as the frequency of the applied electric field, then the material is linear. Given a fixed energy at the applied electric field frequency, the higher the energy of the material's electrical response at other frequencies, the lower the linearity of the material. Compared to silicon, the aforementioned materials exhibit lower energy in their electrical responses at other frequencies given a fixed energy at the applied electric field frequency, thus qualifying as highly linear materials.

[0054] Figure 1A The diagram shows the electric field lines of the main edge parasitic electric field of the bottom electrode. If... Figure 1 The support layer is made of a highly linear material, which can significantly reduce the nonlinear current from the non-electrode connection of the bottom electrode to the top electrode, reduce the intensity of the edge parasitic electric field, and thus improve... Figure 1 The linearity of the resonator in the circuit.

[0055] exist Figure 1 In the resonator shown, the top electrode does not have a bridge structure. However, the invention is not limited to this, and the top electrode may also have a bridge structure. Figure 2 This is a schematic cross-sectional view of a bulk acoustic resonator according to another exemplary embodiment of the present invention. Figure 2 The structure shown is the same as Figure 1 The difference in the structure shown is that, Figure 2 The top electrode is equipped with a bridge structure 115.

[0056] Because of the bridge structure 115, there is a cavity or non-conductive dielectric cavity defined by the bridge structure, which further reduces the intensity of the edge parasitic electric field, thereby further reducing the nonlinearity of the resonator.

[0057] exist Figure 2 In the structure shown, the inner edge of the bridge structure (i.e., the inner edge of the cavity it defines) is located inside the non-electrode connection end of the bottom electrode in the horizontal direction. Figure 2 In the structure shown, the inner edge of the bridge structure is outside the edge of the acoustic mirror; alternatively, the inner edge of the bridge structure can also be inside the edge of the acoustic mirror. See also Figure 2 The outer edge of the bridge structure (i.e., the outer edge of the cavity it defines) is located outside the non-electrode connection end of the bottom electrode in the horizontal direction. In one embodiment of the invention, the cavity defined by the bridge structure needs to span the end of the non-electrode connection end of the bottom electrode.

[0058] exist Figure 2 In the middle, the non-electrode connection end of the bottom electrode is located between the inner and outer edges of the bridge structure in the horizontal direction. Compared with other positional relationships between the non-electrode connection end of the bottom electrode and the inner and outer edges of the bridge structure, this is more conducive to reducing the intensity of the parasitic electric field at the edge, thereby further reducing the nonlinearity of the resonator.

[0059] exist Figure 1 and Figure 2 In the embodiment shown, the non-electrode connection end of the bottom electrode is covered or wrapped by the support layer 105. In this case, it is required that the material of the support layer wrapping the non-electrode connection end of the bottom electrode is a high linear material, but the present invention is not limited thereto.

[0060] Figure 3 This is a schematic cross-sectional view of a bulk acoustic resonator according to yet another exemplary embodiment of the present invention. Figure 3 The structure shown is Figure 1 The difference in the structure shown is that, Figure 3 In the middle, the non-electrode connection terminal of the bottom electrode 107 (i.e. Figure 3 The right end of the middle section is not covered or wrapped by the support layer 105, but is spaced apart from the support layer 105 by a distance d in the horizontal direction. Therefore, in Figure 3 In the example shown, a gap layer with a width d exists horizontally between the non-electrode connection end of the bottom electrode and the support layer. As can be understood, in Figure 3 In this context, the gap layer can be an air gap layer (or void layer) or a vacuum gap layer. Although not shown, as those skilled in the art will understand, the gap layer can also be other non-conductive dielectric layers.

[0061] In one embodiment of the present invention, if the gap layer is an air gap layer or a vacuum gap layer, then the width d is not less than 10 μm.

[0062] exist Figure 3 In the present invention, the top electrode 111 does not have a bridge structure. However, the present invention is not limited thereto, and the top electrode may also have a bridge structure. Figure 4A and Figure 4B This is a schematic cross-sectional view of a bulk acoustic resonator according to another exemplary embodiment of the present invention. Figure 4A and Figure 4B The structure shown is the same as Figure 3 The difference in the structure shown is that, Figure 4A and Figure 4B The top electrode is equipped with a bridge structure 115.

[0063] Because of the bridge structure 115, there is a cavity or non-conductive dielectric cavity defined by the bridge structure, which further reduces the intensity of the edge parasitic electric field, thereby further reducing the nonlinearity of the resonator.

[0064] exist Figure 4A and Figure 4B In the illustrated structure, the inner edge of the bridge structure (i.e., the inner edge of the cavity it defines) is located inside the non-electrode connection end of the bottom electrode in the horizontal direction. As those skilled in the art will understand, the inner edge of the bridge structure can also be outside the non-electrode connection end of the bottom electrode. See also... Figure 4A and Figure 4B The outer edge of the bridge structure (i.e., the outer edge of the cavity it defines) is located outside the non-electrode connection end of the bottom electrode in the horizontal direction. As those skilled in the art will understand, the outer edge of the bridge structure may also be inside the non-electrode connection end of the bottom electrode.

[0065] exist Figure 4A and Figure 4BIn the middle, the non-electrode connection end of the bottom electrode is located between the inner and outer edges of the bridge structure in the horizontal direction. Compared with other positional relationships between the non-electrode connection end of the bottom electrode and the inner and outer edges of the bridge structure, this is more conducive to reducing the intensity of the parasitic electric field at the edge, thereby further reducing the nonlinearity of the resonator.

[0066] Figure 4A and Figure 4B The difference in the structures shown lies in the shape of the acoustic mirror cavity, which is determined by the manufacturing process. Figure 4A In the middle, the boundary of the acoustic mirror cavity forms an obtuse angle with the upper surface of the substrate 101. Figure 6A-6K The fabrication process for forming an acoustic mirror cavity with an acute angle is shown in the diagram. Figure 4B In the middle, the boundary of the acoustic mirror cavity forms an acute angle with the upper surface of the substrate 101.

[0067] Figure 5 This is a cross-sectional schematic diagram of a bulk acoustic resonator according to another exemplary embodiment of the present invention. Figure 5 The structure shown is Figure 4A The difference is that, in Figure 5 As mentioned earlier, the acoustic mirror cavity is a cavity recessed into the support layer. In other words, the lower side or lower boundary of the acoustic mirror cavity is defined by the support layer 105.

[0068] exist Figure 5 In the middle, the top electrode is equipped with a bridge structure, however, Figure 5 The top electrode in the process may not require a bridge structure. Figure 5 In the middle, the non-electrode connection end of the bottom electrode is not wrapped by the support layer 105, however, Figure 5 The non-electrode connection terminal of the middle bottom electrode can also be used Figure 1 and Figure 2 The arrangement shown is within the scope of protection of this invention.

[0069] The following is a reference to the appendix. Figure 6A-6K Exemplary Description Figure 1 The fabrication process of the bulk acoustic resonator is shown.

[0070] like Figure 6A As shown, a piezoelectric thin film layer 109, such as single-crystal aluminum nitride (AlN) or gallium nitride (GaN), is grown on the surface of an auxiliary substrate 102 (such as silicon or silicon carbide). The deposition process used includes, but is not limited to, MOCVD (metal-organic chemical vapor deposition), MBE (molecular beam epitaxy), CBE (chemical molecular beam epitaxy), LPE (liquid phase epitaxy), etc.; or a boundary layer is formed on the surface of the auxiliary substrate 102 (such as lithium niobate or lithium tantalate substrate) by ion implantation, and a piezoelectric layer 109 is formed above the boundary layer. In this case, the material of the piezoelectric layer 109 is the same as the material of the auxiliary substrate 102.

[0071] like Figure 6B As shown, a metal layer is deposited on the surface of the piezoelectric layer 109 and the metal layer is patterned into a bottom electrode 107.

[0072] like Figure 6C As shown, in Figure 6B A sacrificial material layer, which may be silicon dioxide, is deposited on the surface of the piezoelectric layer 109 and the bottom electrode 107 of the obtained structure. The sacrificial material layer is then patterned to obtain the sacrificial material layer 104.

[0073] like Figure 6D As shown, in Figure 6C The resulting structure has a piezoelectric layer 109, a sacrificial material layer 104, and a bottom electrode 107 with a surface-deposited support material layer (denoted as 105). The material of the support material layer is, for example, doped aluminum nitride.

[0074] like Figure 6E As shown, the support material layer is ground smooth using CMP (chemical mechanical polishing) until the sacrificial material layer 104 is exposed, and the support material layer becomes the support layer 105. Figure 6E As shown, the support layer 105 wraps around the end of the bottom electrode (in Figure 6E (In the middle, including the left and right ends).

[0075] like Figure 6F As shown, the substrate 101 is bonded to one side of the support layer 105 and the sacrificial material layer 104. Optionally, the surface of the substrate 101 may also have an auxiliary bonding layer (not shown in the figure), such as silicon dioxide, silicon nitride, or other materials.

[0076] like Figure 6G As shown, Figure 6F The structure is flipped, and the auxiliary substrate 102 is removed by grinding, etching or ion implantation to expose the upper surface of the piezoelectric layer 109. Optionally, the separation interface is subjected to CMP treatment to make its surface smooth and have low roughness.

[0077] like Figure 6H As shown, an electrode material layer for the top electrode 111 is deposited, and then the electrode material layer is patterned to obtain the top electrode 111.

[0078] like Figure 6I As shown, a via 112 is etched in the piezoelectric layer 109 by photolithography and etching processes. At the same time, a sacrificial layer release hole (not shown in the figure) is etched on the piezoelectric layer 109. The via directly connects to the electrode connection end of the bottom electrode, or the via directly connects to the acoustic mirror cavity or directly connects to the sacrificial material layer located in the acoustic mirror cavity.

[0079] like Figure 6J As shown, conductive material is deposited at the through-hole 112 to form the bottom electrode lead-out portion 113.

[0080] like Figure 6K As shown, an etchant is introduced through a release hole to release the sacrificial material layer 104 within the acoustic mirror cavity 103, in order to obtain a corresponding... Figure 1 The structure.

[0081] In the above manufacturing process, the sacrificial material layer 104 is fabricated first, followed by the support layer 105. This results in an obtuse angle between the boundary of the support layer and the surface of the substrate 101. Figure 1 or Figure 4A or Figure 6K As shown. Depending on the manufacturing process, for example, in the above manufacturing process, if the support layer 105 is manufactured first, and then the sacrificial material layer 104 is manufactured, the angle between the boundary of the support layer and the surface of the substrate 101 can be an acute angle, such as... Figure 4B As shown.

[0082] In the above fabrication process, if the material of the bottom electrode lead-out portion 113 is the same as the material of the top electrode 111, a through-hole 112 can be formed on the piezoelectric layer 109 first, and then an electrode material layer can be deposited and patterned on the piezoelectric layer to simultaneously form the bottom electrode lead-out portion 113 and the top electrode 111. However, if the piezoelectric layer also has a release hole communicating with the acoustic mirror cavity, an electrode material layer will also be deposited in the release hole during the formation of the top electrode 111. Therefore, there is a subsequent step of etching away the electrode material in the release hole.

[0083] Based on the above, the present invention also proposes a method for manufacturing a bulk acoustic resonator, comprising the steps of: providing a support layer between a substrate and a piezoelectric layer, such that the piezoelectric layer and the substrate are spaced apart from each other in the thickness direction of the resonator and are arranged substantially parallel to each other; and providing a high linearity material layer on the outer side of the non-electrode connection end of the bottom electrode in the horizontal direction. (Referring to the above...) Figure 6A-6K In the described process, the high linearity material layer is a support layer. However, as mentioned earlier, the high linearity material layer can also be, for example, a void layer or an insulating dielectric layer.

[0084] It should be noted that, in this invention, each numerical range, except where explicitly stated not to include endpoint values, can be either an endpoint value or the median of each numerical range, and all of these are within the protection scope of this invention.

[0085] In this invention, "upper" and "lower" are relative to the bottom surface of the resonator's base. For a component, the side closer to the bottom surface is the lower side, and the side farther from the bottom surface is the upper side.

[0086] In this invention, "inner" and "outer" are relative to the center (i.e., the center of the effective region) of the resonator (the overlapping area of ​​the piezoelectric layer, top electrode, bottom electrode, and acoustic mirror in the thickness direction of the resonator constitutes the effective region) in the lateral or radial direction. A component's side or end closer to the center of the effective region is called the inner side or inner end, while the side or end of the component farther from the center of the effective region is called the outer side or outer end. For a reference position, being inside the position means being between that position and the center of the effective region in the lateral or radial direction, while being outside the position means being farther from the center of the effective region in the lateral or radial direction than that position.

[0087] As will be understood by those skilled in the art, the bulk acoustic resonator according to the present invention can be used to form filters or electronic devices.

[0088] Based on the above, the present invention proposes the following technical solution:

[0089] 1. A bulk acoustic resonator, comprising:

[0090] Base;

[0091] Acoustic mirror;

[0092] Bottom electrode;

[0093] Top electrode; and

[0094] A piezoelectric layer is disposed between the bottom electrode and the top electrode.

[0095] in:

[0096] The piezoelectric layer is a flat piezoelectric layer, and a support layer is provided between the substrate and the piezoelectric layer. The piezoelectric layer and the substrate are spaced apart from each other in the thickness direction of the resonator and are arranged generally parallel to each other.

[0097] The non-electrode connection end of the bottom electrode is provided with a high linearity material layer on its outer side in the horizontal direction.

[0098] 2. The resonator according to 1, wherein:

[0099] The non-electrode connection end of the bottom electrode is covered by the support layer and is located between the piezoelectric layer and the support layer in the thickness direction of the resonator, and the outer edge of the support layer is located outside the non-electrode connection end of the bottom electrode in the horizontal direction; and

[0100] The support layer is a high linearity material support layer, and the support layer on the outer side of the non-electrode connection end of the bottom electrode in the horizontal direction constitutes the high linearity material layer.

[0101] 3. The resonator according to 1, wherein:

[0102] The non-electrode connection end of the bottom electrode has a gap layer between it and the support layer in the horizontal direction. The gap layer is an air gap layer, a vacuum gap layer, or a solid insulating dielectric layer. When the gap layer is an air gap layer or a vacuum gap layer, the width of the gap layer is not less than 10 μm.

[0103] 4. The resonator according to 3, wherein:

[0104] The support layer is a high linearity material support layer.

[0105] 5. The resonator according to claim 1, wherein:

[0106] The area corresponding to the non-electrode connection end of the bottom electrode of the top electrode is flat.

[0107] 6. The resonator according to claim 1, wherein:

[0108] The top electrode includes a bridge structure in the region corresponding to the non-electrode connection end of the bottom electrode.

[0109] 7. The resonator according to 6, wherein:

[0110] The inner edge of the bridge structure is located inside the outer edge of the non-electrode connection end of the bottom electrode in the horizontal direction.

[0111] 8. The resonator according to 7, wherein:

[0112] At the electrode connection end of the top electrode, the outer edge of the bridge structure is located outside the inner edge of the support layer in the horizontal direction; or

[0113] The outer edge of the bridge structure is located outside the outer edge of the non-electrode connection end of the bottom electrode in the horizontal direction.

[0114] 9. The resonator according to claim 1, wherein:

[0115] The support layer is made of one of the following materials: non-etchable borosilicate glass (NEBSG), silicon dioxide, doped silicon dioxide, aluminum nitride, doped aluminum nitride, gallium arsenide, gallium nitride, silicon carbide, or silicon nitride.

[0116] 10. The resonator according to claim 1, wherein:

[0117] The acoustic mirror is an acoustic mirror cavity; and

[0118] The support layer defines the boundaries of the acoustic mirror in the horizontal direction.

[0119] 11. The resonator according to 10, wherein:

[0120] The boundary of the cavity forms an obtuse angle with the upper surface of the substrate.

[0121] 12. The resonator according to 10, wherein:

[0122] The boundary of the cavity forms an acute angle with the upper surface of the substrate.

[0123] 13. The resonator according to 10, wherein:

[0124] The lower boundary of the acoustic mirror cavity is defined by the upper surface of the substrate.

[0125] 14. The resonator according to 10, wherein:

[0126] The acoustic mirror cavity is recessed into the support layer, and the lower boundary of the acoustic mirror cavity is defined by the support layer.

[0127] 15. The resonator according to any one of 1-14, wherein:

[0128] The electrode connection end of the bottom electrode is covered by the support layer and is located between the piezoelectric layer and the support layer in the thickness direction of the resonator.

[0129] 16. The resonator according to 15, wherein:

[0130] The outer edge of the support layer is located outside the electrode connection end of the bottom electrode in the horizontal direction; and the piezoelectric layer is provided with a through hole. The resonator also includes an electrode lead-out portion electrically connected to the electrode connection end of the bottom electrode through the through hole. A portion of the electrode lead-out portion is located on the upper surface of the piezoelectric layer and arranged in the same layer as the top electrode.

[0131] 17. The resonator according to any one of 1-14, wherein:

[0132] The piezoelectric layer is a single-crystal piezoelectric layer.

[0133] 18. The resonator according to 17, wherein:

[0134] The piezoelectric layer is made of single-crystal aluminum nitride, single-crystal gallium nitride, single-crystal lithium niobate, single-crystal potassium niobate, single-crystal quartz film, or single-crystal lithium tantalate.

[0135] 19. A method for manufacturing a bulk acoustic resonator, the bulk acoustic resonator comprising a substrate, an acoustic mirror, a bottom electrode, a top electrode, and a piezoelectric layer, wherein the piezoelectric layer is disposed between the bottom electrode and the top electrode and is a flat piezoelectric layer.

[0136] The method includes the following steps:

[0137] A support layer is provided between the substrate and the piezoelectric layer, such that the piezoelectric layer and the substrate are spaced apart from each other and are generally parallel to each other in the thickness direction of the resonator.

[0138] A high linearity material layer is disposed on the outer side of the non-electrode connection end of the bottom electrode in the horizontal direction.

[0139] 20. According to the method described in 19, wherein:

[0140] The steps for setting the support layer include forming the support layer using a highly linear material;

[0141] The step of “setting a high linearity material layer on the outer side of the non-electrode connection end of the bottom electrode in the horizontal direction” includes: such that the support layer covers the non-electrode connection end of the bottom electrode, and the outer edge of the support layer is located on the outer side of the non-electrode connection end of the bottom electrode in the horizontal direction.

[0142] 21. According to the method described in 19, wherein:

[0143] The step of “setting a high linearity material layer on the outer side of the non-electrode connection end of the bottom electrode in the horizontal direction” includes: creating a gap layer in the horizontal direction between the non-electrode connection end of the bottom electrode and the support layer, wherein the gap layer is an air gap layer, a vacuum gap layer, or a solid insulating dielectric layer, and the width of the gap layer is not less than 10 μm when the gap layer is an air gap layer or a vacuum gap layer.

[0144] 22. According to the method described in 19, wherein:

[0145] The piezoelectric layer is a single-crystal piezoelectric layer.

[0146] 23. According to the method described in 22, wherein:

[0147] The piezoelectric layer is made of single-crystal aluminum nitride, single-crystal gallium nitride, single-crystal lithium niobate, single-crystal potassium niobate, single-crystal quartz film, or single-crystal lithium tantalate.

[0148] 24. A filter comprising a bulk acoustic resonator according to any one of 1-18.

[0149] 25. An electronic device comprising the filter according to claim 24, or the bulk acoustic resonator according to any one of claims 1-18.

[0150] The electronic devices mentioned here include, but are not limited to, intermediate products such as radio frequency front-ends and filtering and amplification modules, as well as terminal products such as mobile phones, WIFI, and drones.

[0151] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that variations may be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A bulk acoustic resonator, comprising: Base; Acoustic mirror; Bottom electrode; Top electrode; and A piezoelectric layer is disposed between the bottom electrode and the top electrode. in: The piezoelectric layer is a flat piezoelectric layer, and a support layer is provided between the substrate and the piezoelectric layer. The piezoelectric layer and the substrate are spaced apart from each other in the thickness direction of the resonator and are arranged generally parallel to each other. The non-electrode connection end of the bottom electrode is provided with a high linearity material layer on the outer side in the horizontal direction; The top electrode includes a bridge structure in the corresponding region of the non-electrode connection end of the bottom electrode; A cavity is defined between the bridge structure and the piezoelectric layer, and the cavity and the highly linear material layer work together to reduce the intensity of the edge parasitic electric field at the non-electrode connection end of the bottom electrode.

2. The resonator according to claim 1, wherein: The non-electrode connection end of the bottom electrode is covered by the support layer and is located between the piezoelectric layer and the support layer in the thickness direction of the resonator, and the outer edge of the support layer is located outside the non-electrode connection end of the bottom electrode in the horizontal direction; and The support layer is a high linearity material support layer, and the support layer on the outer side of the non-electrode connection end of the bottom electrode in the horizontal direction constitutes the high linearity material layer.

3. The resonator according to claim 1, wherein: The non-electrode connection end of the bottom electrode has a gap layer between it and the support layer in the horizontal direction. The gap layer is an air gap layer, a vacuum gap layer, or a solid insulating dielectric layer. When the gap layer is an air gap layer or a vacuum gap layer, the width of the gap layer is not less than 10 μm.

4. The resonator according to claim 3, wherein: The support layer is a high linearity material support layer.

5. The resonator according to claim 1, wherein: The inner edge of the bridge structure is located inside the outer edge of the non-electrode connection end of the bottom electrode in the horizontal direction.

6. The resonator according to claim 5, wherein: At the electrode connection end of the top electrode, the outer edge of the bridge structure is located outside the inner edge of the support layer in the horizontal direction; or The outer edge of the bridge structure is located outside the outer edge of the non-electrode connection end of the bottom electrode in the horizontal direction.

7. The resonator according to claim 1, wherein: The support layer is made of one of the following materials: non-etchable borosilicate glass (NEBSG), silicon dioxide, doped silicon dioxide, aluminum nitride, doped aluminum nitride, gallium arsenide, gallium nitride, silicon carbide, or silicon nitride.

8. The resonator according to claim 1, wherein: The acoustic mirror is an acoustic mirror cavity; and The support layer defines the boundaries of the acoustic mirror in the horizontal direction.

9. The resonator according to claim 8, wherein: The boundary of the cavity forms an obtuse angle with the upper surface of the substrate.

10. The resonator according to claim 8, wherein: The boundary of the cavity forms an acute angle with the upper surface of the substrate.

11. The resonator according to claim 8, wherein: The lower boundary of the acoustic mirror cavity is defined by the upper surface of the substrate.

12. The resonator according to claim 8, wherein: The acoustic mirror cavity is recessed into the support layer, and the lower boundary of the acoustic mirror cavity is defined by the support layer.

13. The resonator according to any one of claims 1-12, wherein: The electrode connection end of the bottom electrode is covered by the support layer and is located between the piezoelectric layer and the support layer in the thickness direction of the resonator.

14. The resonator according to claim 13, wherein: The outer edge of the support layer is located outside the electrode connection end of the bottom electrode in the horizontal direction; and the piezoelectric layer is provided with a through hole. The resonator also includes an electrode lead-out portion electrically connected to the electrode connection end of the bottom electrode through the through hole. A portion of the electrode lead-out portion is located on the upper surface of the piezoelectric layer and arranged in the same layer as the top electrode.

15. The resonator according to any one of claims 1-12, wherein: The piezoelectric layer is a single-crystal piezoelectric layer.

16. The resonator according to claim 15, wherein: The piezoelectric layer is made of single-crystal aluminum nitride, single-crystal gallium nitride, single-crystal lithium niobate, single-crystal potassium niobate, single-crystal quartz film, or single-crystal lithium tantalate.

17. A method for manufacturing a bulk acoustic resonator, the bulk acoustic resonator comprising a substrate, an acoustic mirror, a bottom electrode, a top electrode, and a piezoelectric layer, wherein the piezoelectric layer is disposed between the bottom electrode and the top electrode and is a flat piezoelectric layer. The method includes the following steps: A support layer is provided between the substrate and the piezoelectric layer, such that the piezoelectric layer and the substrate are spaced apart from each other and are generally parallel to each other in the thickness direction of the resonator. A high linearity material layer is disposed on the outer side of the non-electrode connection end of the bottom electrode in the horizontal direction; The top electrode includes a bridge structure in the corresponding region of the non-electrode connection end of the bottom electrode; A cavity is defined between the bridge structure and the piezoelectric layer, and the cavity and the highly linear material layer work together to reduce the intensity of the edge parasitic electric field at the non-electrode connection end of the bottom electrode.

18. The method of claim 17, wherein: The steps for setting the support layer include forming the support layer using a highly linear material; The step of "providing a high linearity material layer on the outer side of the non-electrode connection end of the bottom electrode in the horizontal direction" includes: such that the support layer covers the non-electrode connection end of the bottom electrode, and the outer edge of the support layer is located on the outer side of the non-electrode connection end of the bottom electrode in the horizontal direction.

19. The method of claim 17, wherein: The step of "setting a high linearity material layer on the outer side of the non-electrode connection end of the bottom electrode in the horizontal direction" includes: creating a gap layer in the horizontal direction between the non-electrode connection end of the bottom electrode and the support layer, wherein the gap layer is an air gap layer, a vacuum gap layer, or a solid insulating dielectric layer, and the width of the gap layer is not less than 10 μm when the gap layer is an air gap layer or a vacuum gap layer.

20. The method of claim 17, wherein: The piezoelectric layer is a single-crystal piezoelectric layer.

21. The method of claim 20, wherein: The piezoelectric layer is made of single-crystal aluminum nitride, single-crystal gallium nitride, single-crystal lithium niobate, single-crystal potassium niobate, single-crystal quartz film, or single-crystal lithium tantalate.

22. A filter comprising a bulk acoustic resonator according to any one of claims 1-16.

23. An electronic device comprising the filter of claim 22, or the bulk acoustic resonator of any one of claims 1-16.

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