Resonator and manufacturing method thereof

Abstract

The embodiment of the invention provides a resonator and a manufacturing method thereof. The resonator comprises a substrate and a resonance function structure arranged on one side of the substrate, wherein the resonance function structure comprises a first electrode layer, a second electrode layer, a piezoelectric layer and a third electrode layer which are sequentially stacked; wherein the distance between the first electrode layer and the substrate is smaller than that between the third electrode layer and the substrate, the material of the first electrode layer is different from that of the second electrode layer, and the lattice matching degree between the piezoelectric layer and the second electrode layer is larger than that between the piezoelectric layer and the first electrode layer.

Description

Technical Field

[0001] The embodiments of the present disclosure relate to the field of semiconductor technology, including but not limited to a resonator and a method for manufacturing the same. Background Art

[0002] Filters are core devices for frequency selection and control in mobile communications and the Internet of Things, and usually include dielectric filters and acoustic wave filters. Dielectric filters are filters formed by coupling multiple dielectric resonators, while acoustic wave filters are based on the principle of sound waves, and use the piezoelectric effect of the piezoelectric layer to achieve mutual conversion and transmission of acoustic resonance to electrical frequency. Among them, the piezoelectric layer, as an important component of the acoustic wave filter, has an important influence on its performance. However, in the current acoustic wave filter, the performance of the piezoelectric layer cannot meet the use requirements of the acoustic wave filter. Summary of the invention

[0003] In view of this, an embodiment of the present disclosure provides a resonator and a method for manufacturing the same.

[0004] In a first aspect, an embodiment of the present disclosure provides a resonator, comprising: a substrate and a resonant functional structure arranged on one side of the substrate, the resonant functional structure comprising a first electrode layer, a second electrode layer, a piezoelectric layer and a third electrode layer stacked in sequence; wherein the distance between the first electrode layer and the substrate is smaller than the distance between the third electrode layer and the substrate, the material of the first electrode layer is different from the material of the second electrode layer, and the lattice matching degree between the piezoelectric layer and the second electrode layer is greater than the lattice matching degree between the piezoelectric layer and the first electrode layer.

[0005] In some embodiments, the crystal structure of the piezoelectric layer is the same as the crystal structure of the second electrode layer; the absolute value of the ratio of the difference between the lattice constant of the piezoelectric layer and the lattice constant of the second electrode layer to the lattice constant of the piezoelectric layer is less than 5%; and / or the absolute value of the ratio of the difference between the lattice constant of the piezoelectric layer and the lattice constant of the second electrode layer is less than 5%.

[0006] In some embodiments, the piezoelectric layer is a single crystal structure; and the half-peak width of a rocking curve of the piezoelectric layer in X-ray diffraction is less than 0.5 degrees.

[0007] In some embodiments, the conductivity of the first electrode layer is greater than the conductivity of the second electrode layer.

[0008] In some embodiments, a size of the first electrode layer along the stacking direction is greater than a size of the second electrode layer along the stacking direction; a size of the first electrode layer along the stacking direction ranges from 50nm to 200nm, and a size of the second electrode layer along the stacking direction ranges from 10nm to 100nm.

[0009] In some embodiments, the resonator further includes: a first cavity disposed between the substrate and the resonant functional structure, the first cavity exposing at least a portion of a surface of the first electrode layer away from the second electrode layer; or, a second cavity disposed in the substrate, the second cavity exposing at least a portion of a surface of the first electrode layer away from the second electrode layer; or, a Bragg structure disposed between the substrate and the resonant functional structure.

[0010] In some embodiments, the material of the piezoelectric layer includes at least one of aluminum nitride, gallium nitride, scandium nitride, aluminum scandium nitride, gallium scandium nitride, indium scandium nitride, aluminum gallium scandium nitride and aluminum gallium scandium indium nitride, wherein the content of scandium element in aluminum scandium nitride, gallium scandium nitride, indium scandium nitride, aluminum gallium scandium nitride and aluminum gallium scandium indium nitride is greater than or equal to 1at%; the material of the first electrode layer includes a metal, and the metal includes at least one of molybdenum, platinum, ruthenium, rhodium, gold, iridium, aluminum, titanium, tungsten, palladium, tantalum, chromium and nickel; the material of the second electrode layer includes a metal nitride, and the metal nitride includes at least one of niobium nitride, tantalum nitride, hafnium nitride and zirconium nitride.

[0011] In some embodiments, the resonator further includes: a buffer layer disposed between the substrate and the resonant functional structure, the buffer layer being used to alleviate the lattice mismatch and thermal mismatch between the substrate and the resonant functional structure; the material of the buffer layer includes at least one of aluminum nitride, gallium nitride, indium nitride, indium gallium nitride and aluminum gallium nitride.

[0012] In a second aspect, an embodiment of the present disclosure provides a method for manufacturing a resonator, the method comprising: providing a substrate; forming a resonant functional structure on one side of the substrate, the resonant functional structure comprising a first electrode layer, a second electrode layer, a piezoelectric layer and a third electrode layer stacked in sequence; wherein the distance between the first electrode layer and the substrate is smaller than the distance between the third electrode layer and the substrate, the material of the first electrode layer is different from the material of the second electrode layer, and the lattice matching degree between the piezoelectric layer and the second electrode layer is greater than the lattice matching degree between the piezoelectric layer and the first electrode layer.

[0013] In some embodiments, the piezoelectric layer is formed using a chemical vapor deposition process; the deposition pressure range of the piezoelectric layer is 50 torr to 500 torr, and the deposition temperature range is 600° C. to 1200° C.

[0014] The embodiment of the present disclosure provides a resonator and a method for manufacturing the same. The resonator includes: a substrate and a resonant functional structure arranged on one side of the substrate, the resonant functional structure includes a first electrode layer, a second electrode layer, a piezoelectric layer and a third electrode layer stacked in sequence; wherein the distance between the first electrode layer and the substrate is smaller than the distance between the third electrode layer and the substrate, the material of the first electrode layer is different from the material of the second electrode layer, and the lattice matching degree between the piezoelectric layer and the second electrode layer is greater than the lattice matching degree between the piezoelectric layer and the first electrode layer. Compared with forming a piezoelectric layer on the first electrode layer, the piezoelectric layer and the first electrode layer are in contact, in the embodiment of the present disclosure, the second electrode layer is formed on the first electrode layer, and the piezoelectric layer is formed on the second electrode layer, and the piezoelectric layer and the second electrode layer are in contact. Since the lattice matching degree between the piezoelectric layer and the second electrode layer is greater than the lattice matching degree between the piezoelectric layer and the first electrode layer, the film quality of the piezoelectric layer can be improved, thereby improving the performance of the resonator. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A cross-sectional schematic diagram of a resonator provided in an embodiment of the present disclosure;

[0016] Figure 2 A block diagram of an acoustic wave device provided for an embodiment of the present disclosure;

[0017] Figure 3 A schematic diagram of a process for manufacturing a resonator provided in an embodiment of the present disclosure;

[0018] Figure 4 X-ray diffraction rocking curves of the piezoelectric layers provided for the examples and comparative examples.

[0019] The figure includes: 100, resonator; 102, substrate; 104, resonant functional structure; 106, first electrode layer; 108, second electrode layer; 110, piezoelectric layer; 112, third electrode layer; 114, buffer layer; 200, acoustic wave device. DETAILED DESCRIPTION

[0020] The following will be combined with the embodiments of the present disclosure and the accompanying drawings to clearly and completely describe the technical solutions in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0021] In the following description, a large number of specific details are given to provide a more thorough understanding of the present disclosure. However, it is obvious to those skilled in the art that the present disclosure can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present disclosure, some technical features known in the art are not described; that is, all features of actual embodiments are not described here, and well-known functions and structures are not described in detail.

[0022] In the drawings, the sizes of layers, regions, elements and their relative sizes may be exaggerated for clarity. Like reference numerals denote like elements throughout.

[0023] It should be understood that when an element or layer is referred to as "on ...", "adjacent to ...", "connected to" or "coupled to" other elements or layers, it can be directly on, adjacent to, connected to or coupled to other elements or layers, or there can be intervening elements or layers. On the contrary, when an element is referred to as "directly on ...", "directly adjacent to ...", "directly connected to" or "directly coupled to" other elements or layers, there is no intervening element or layer. It should be understood that although the terms first, second, third, etc. can be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present disclosure, the first element, component, region, layer or part discussed below can be represented as the second element, component, region, layer or part. And when the second element, component, region, layer or part is discussed, it does not indicate that the present disclosure necessarily has the first element, component, region, layer or part.

[0024] Spatially relative terms such as "under", "beneath", "below", "under", "above", "above", etc., may be used here for convenience of description to describe the relationship between an element or feature shown in the figure and other elements or features. It should be understood that in addition to the orientation shown in the figure, the spatial relationship terms are intended to also include different orientations of the device in use and operation. For example, if the device in the accompanying drawings is turned over, then the elements or features described as "under other elements" or "under it" or "under it" will be oriented as "on" other elements or features. Therefore, the exemplary terms "under" and "under" may include both upper and lower orientations. The device can be oriented otherwise (rotated 90 degrees or other orientations) and the spatial descriptors used herein are interpreted accordingly.

[0025] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be a limitation of the present disclosure. When used herein, the singular forms "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0026] In order to thoroughly understand the present disclosure, detailed steps and detailed structures will be presented in the following description to illustrate the technical solution of the present disclosure. The preferred embodiments of the present disclosure are described in detail below, but in addition to these detailed descriptions, the present disclosure may also have other implementations.

[0027] Since the 4G era, the mainstream mode of mobile phone filters has become acoustic wave filters, which include surface acoustic wave (SAW) filters and body acoustic wave (BAW) filters. Among them, the performance of BAW filters is more suitable for medium and high frequency bands, and is considered to be the technology with the highest penetration rate in future RF front-ends and filters. Unlike SAW filters, acoustic waves propagate vertically in BAW filters. The basic structure of BAW filters includes a lower electrode layer, a piezoelectric layer and an upper electrode layer. When an alternating voltage with a certain frequency is applied to the upper electrode layer above the piezoelectric layer and the lower electrode layer below the piezoelectric layer, the piezoelectric layer undergoes mechanical deformation due to the inverse piezoelectric effect, thereby exciting elastic waves propagating along the thickness direction of the piezoelectric layer. The elastic waves will be reflected back at the interface between the upper and lower electrode layers and the outside world, and then reflect back and forth in the piezoelectric layer to form standing waves.

[0028] For BAW filters, the electromechanical coupling coefficient and quality factor are both very important performance parameters. In this article, the "electromechanical coupling coefficient" refers to the conversion efficiency between the applied electrical energy and the generated mechanical energy, which determines the bandwidth of the BAW filter; the "quality factor" in this article refers to the ratio of stored energy to lost energy per vibration cycle, which determines the insertion loss of the BAW filter. The material type and crystal quality of the piezoelectric layer are closely related to the above two performance parameters. Therefore, improving the crystal quality of the piezoelectric layer is of great significance to improving the performance of the BAW filter.

[0029] In view of this, an embodiment of the present disclosure provides a resonator and a method for manufacturing the same.

[0030] Before introducing the embodiments of the present disclosure, various directions that may be involved in the following are defined. A first direction (i.e., the X direction) and a second direction (i.e., the Y direction) that intersect are defined in the plane where the substrate is located, and a direction perpendicular to the substrate is defined as a third direction (i.e., the Z direction). In some embodiments, the X direction and the Y direction may not be perpendicular to each other. In other embodiments, the X direction and the Y direction are perpendicular to each other, so that any two of the X direction, the Y direction, and the Z direction are perpendicular to each other. In the following embodiments, the example in which any two of the X direction, the Y direction, and the Z direction are perpendicular to each other will be used for illustration.

[0031] refer to Figure 1 , Figure 1 Schematic diagram of a cross-section of a resonator provided in an embodiment of the present disclosure. Figure 1 As shown, an embodiment of the present disclosure provides a resonator, the resonator 100 comprising: a substrate 102 and a resonant functional structure 104 arranged on one side of the substrate 102 along the Z direction, the resonant functional structure 104 comprising a first electrode layer 106, a second electrode layer 108, a piezoelectric layer 110 and a third electrode layer 112 stacked in sequence along the Z direction; wherein the distance between the first electrode layer 106 and the substrate 102 is smaller than the distance between the third electrode layer 112 and the substrate 102, the material of the first electrode layer 106 is different from the material of the second electrode layer 108, and the lattice matching degree between the piezoelectric layer 110 and the second electrode layer 108 is greater than the lattice matching degree between the piezoelectric layer 110 and the first electrode layer 106.

[0032] Here, the substrate 102 is a growth and support substrate in the subsequent epitaxial growth process of each material layer. In the embodiment of the present disclosure, the substrate 102 can be a semiconductor substrate.

[0033] In some embodiments, the material of the substrate 102 may include, but is not limited to, at least one of sapphire, silicon carbide (SiC), silicon (Si), and gallium nitride (GaN).

[0034] Here, a resonant functional structure 104 is formed on a substrate 102, a first electrode layer 106 in the resonant functional structure 104 is close to the substrate 102, and a third electrode layer 112 in the resonant functional structure 104 is far away from the substrate 102. The first electrode layer 106 and the second electrode layer 108 can both be referred to as lower electrode layers, and the first electrode layer 106 and the second electrode layer 108 together form a composite lower electrode layer. Correspondingly, the third electrode layer 112 can be referred to as an upper electrode layer. Electric energy can be applied to the resonator through the composite lower electrode layer and the upper electrode layer. Among them, the first electrode layer 106, the second electrode layer 108, and the third electrode layer 112 can all be used for connecting electrical signals, and the second electrode layer 108 can also be used to alleviate the lattice mismatch between the piezoelectric layer 110 and the first electrode layer 106 during the growth process of the piezoelectric layer 110.

[0035] In this article, "lattice mismatch" refers to the mismatch phenomenon caused by the different lattice constants of the first electrode layer and the piezoelectric layer. If a piezoelectric layer is grown on the first electrode layer, due to the different lattice constants of the first electrode layer and the piezoelectric layer, stress will be generated near the growth interface, thereby generating crystal defects - mismatch dislocations.

[0036] In some embodiments, the conductivity of the first electrode layer 106 is greater than the conductivity of the second electrode layer 108. Here, the role of the first electrode layer 106 focuses on the connection of electrical signals, and the role of the second electrode layer 108 focuses on alleviating lattice mismatch. Therefore, the conductivity of the first electrode layer 106 is better than the conductivity of the second electrode layer 108. The conductivity can be characterized by conductivity or resistivity. Conductivity can be used to measure the ability of a material layer to conduct current, and resistivity can be used to measure the hindering effect of a material layer on current. In short, the greater the conductivity, the better the conductivity of the material layer; the smaller the resistivity, the better the conductivity of the material layer.

[0037] In some embodiments, the conductivity of the first electrode layer 106 is greater than the conductivity of the second electrode layer 108 .

[0038] In some embodiments, the resistivity of the first electrode layer 106 is less than the resistivity of the second electrode layer 108. For example, the resistivity of the second electrode layer 108 is ≤5×10 -5 Ω·m.

[0039] In some embodiments, the material of the first electrode layer 106 includes metal, and the material of the second electrode layer 108 includes metal nitride. Here, the first electrode layer 106 is made of a metal material with good electrical conductivity, which can better achieve the connection of electrical signals, and the second electrode layer 108 is made of a metal nitride material with good electrical conductivity and higher lattice matching with the piezoelectric layer 110, which can achieve electrical signal connection and alleviate the lattice mismatch between the first electrode layer 106 and the piezoelectric layer 110.

[0040] In some embodiments, the material of the first electrode layer 106 includes at least one of molybdenum (Mo), platinum (Pt), ruthenium (Ru), rhodium (Rh), gold (Au), iridium (Ir), aluminum (Al), titanium (Ti), tungsten (W), palladium (Pd), tantalum (Ta), chromium (Cr) and nickel (Ni); the material of the second electrode layer 108 includes at least one of niobium nitride (NbN), tantalum nitride (TaN), hafnium nitride (HfN) and zirconium nitride (ZrN).

[0041] In some embodiments, the size of the first electrode layer 106 along the Z direction is greater than the size of the second electrode layer 108 along the Z direction. Here, the size of the first electrode layer 106 along the Z direction is the thickness of the first electrode layer 106, and the size of the second electrode layer 108 along the Z direction is the thickness of the second electrode layer 108. Since the conductivity of the first electrode layer 106 is greater than the conductivity of the second electrode layer 108, when the thickness of the first electrode layer 106 is greater than the thickness of the second electrode layer 108, the second electrode layer 108 can be used to alleviate the lattice mismatch between the piezoelectric layer 110 and the first electrode layer 106 during the growth process of the piezoelectric layer 110, and the conductivity of the composite lower electrode layer (that is, the first electrode layer 106 and the second electrode layer 108) can also be improved.

[0042] In some embodiments, the size of the first electrode layer 106 along the Z direction ranges from 50nm to 200nm. Exemplarily, the thickness of the first electrode layer 106 may be 50nm, 60nm, 80nm, 100nm, 120nm, 140nm, 160nm, 180nm or 200nm; the size of the second electrode layer 108 along the Z direction ranges from 10nm to 100nm. Exemplarily, the thickness of the second electrode layer 108 may be 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm or 100nm.

[0043] Here, the measurement of "lattice matching" in this article needs to consider the crystal structure and lattice constant between two adjacent material layers. A piezoelectric layer is formed on the first electrode layer, and the piezoelectric layer and the first electrode layer are in contact. Since the first electrode layer is usually made of metal molybdenum, for example, and the piezoelectric layer is usually made of aluminum nitride, for example, an amorphous structure or a polycrystalline structure piezoelectric layer is usually grown on the first electrode layer. The piezoelectric coefficient of the amorphous structure or the polycrystalline structure piezoelectric layer is low, thereby affecting the performance of the resonator.

[0044] In the embodiment of the present disclosure, a second electrode layer 108 is formed on the first electrode layer 106, and the first electrode layer 106 and the second electrode layer 108 are in contact with each other; a piezoelectric layer 110 is formed on the second electrode layer 108, and the second electrode layer 108 and the piezoelectric layer 110 are in contact with each other; the lattice matching degree between the piezoelectric layer 110 and the second electrode layer 108 is higher, which is more conducive to the growth of a single crystal piezoelectric layer 110, and the film quality of the piezoelectric layer 110 can be improved, thereby improving the performance of the resonator 100.

[0045] In some embodiments, the crystal structure of the piezoelectric layer 110 is the same as the crystal structure of the second electrode layer 108; the absolute value of the ratio of the difference between the lattice constant of the piezoelectric layer 110 and the lattice constant of the second electrode layer 108 to the lattice constant of the piezoelectric layer 110 is less than 5%; and / or the absolute value of the ratio of the difference between the lattice constant of the piezoelectric layer 110 and the lattice constant of the second electrode layer 108 is less than 5%.

[0046] Here, the higher lattice matching between the piezoelectric layer 110 and the second electrode layer 108 is reflected in two aspects. First, the crystal structure of the piezoelectric layer 110 is the same as the crystal structure of the second electrode layer 108. Second, the lattice constant of the piezoelectric layer 110 is similar to the lattice constant of the second electrode layer 108, more specifically, -5% < (lattice constant of the piezoelectric layer 110 - lattice constant of the second electrode layer 108) / lattice constant of the piezoelectric layer 110 < 5%; and / or, -5% < (lattice constant of the piezoelectric layer 110 - lattice constant of the second electrode layer 108) / lattice constant of the second electrode layer 108 < 5%. Exemplarily, the ratio between the difference between the lattice constant of the piezoelectric layer 110 and the lattice constant of the second electrode layer 108 and the lattice constant of the piezoelectric layer 110 (or, the lattice constant of the second electrode layer 108) can be ±1%, ±2%, ±3% or ±4%.

[0047] In some embodiments, the crystal structure of the piezoelectric layer 110 and the crystal structure of the second electrode layer 108 are both hexagonal or cubic.

[0048] In some embodiments, the piezoelectric layer 110 is a single crystal structure; the half-peak width of a rocking curve of the piezoelectric layer 110 in X-ray diffraction (XRD) is less than 0.5 degrees.

[0049] Here, the rocking curve in XRD can be used to describe the size of the angular divergence of a specific crystal plane in the sample. The horizontal coordinate of the rocking curve is the angle between a specific crystal plane and the sample plane, ranging from -θ to +θ. The positive angle represents the angle between the specific crystal plane and the sample plane along the counterclockwise rotation, and the negative angle represents the angle between the specific crystal plane and the sample plane along the clockwise rotation. The vertical coordinate of the rocking curve represents the diffraction intensity of the specific crystal plane at a certain specific angle. The rocking curve can be used to characterize the crystal orientation of the piezoelectric layer 110. The full width at half maximum (FWHM) of the rocking curve of the piezoelectric layer 110 is less than 0.5 degrees, indicating that the crystal of the piezoelectric layer 110 is highly oriented and the crystal quality of the piezoelectric layer 110 is higher.

[0050] Here, 1 degree can be converted into 60 arc minutes, and 1 arc minute can be converted into 60 arc seconds. That is, the half-peak width of the rocking curve of the piezoelectric layer 110 is less than 1800 arc seconds.

[0051] In some embodiments, the material of the piezoelectric layer 110 includes at least one of aluminum nitride (AlN), gallium nitride (GaN), scandium nitride (ScN), aluminum scandium nitride (AlScN), gallium scandium nitride (GaScN), indium scandium nitride (InScN), aluminum gallium scandium nitride (AlGaScN) and aluminum gallium scandium indium nitride (AlGaScInN), wherein the content of scandium element in aluminum scandium nitride, gallium scandium nitride, indium scandium nitride, aluminum gallium scandium nitride and aluminum gallium scandium indium nitride is greater than or equal to 1at%.

[0052] Here, the third electrode layer 112 is used for connecting electrical signals. The third electrode layer 112 is formed on the piezoelectric layer 110, that is, the formation process of the piezoelectric layer 110 is before the formation process of the third electrode layer 112, that is, there is no need to consider the influence of the crystal structure of the third electrode layer 112 on the formation of the piezoelectric layer 110, therefore, the material of the third electrode layer 112 can have a wider range of choices.

[0053] In some embodiments, the material of the third electrode layer 112 includes at least one of molybdenum (Mo), platinum (Pt), ruthenium (Ru), rhodium (Rh), gold (Au), iridium (Ir), aluminum (Al), titanium (Ti), tungsten (W), palladium (Pd), tantalum (Ta), chromium (Cr), nickel (Ni), niobium nitride (NbN), tantalum nitride (TaN), hafnium nitride (HfN) and zirconium nitride (ZrN).

[0054] Here, the resonator may further include a reflection structure, which is disposed below the resonant functional structure. The reflection structure is used to reflect the acoustic wave signal. When the acoustic wave signal generated by the piezoelectric layer 110 propagates toward the reflection structure, the acoustic wave signal may be totally reflected at the contact interface between the first electrode layer 106 and the reflection structure, so that the acoustic wave signal is reflected back into the piezoelectric layer 110. In this way, the energy of the acoustic wave signal generated by the piezoelectric layer 110 can be confined in the piezoelectric layer 110, which can reduce the energy loss of the acoustic wave signal.

[0055] Here, the BAW resonator can be divided into a film bulk acoustic wave resonator (FBAR) and a solid mounted resonator (SMR) according to the different reflection structures.

[0056] In some embodiments, the resonator may be an FBAR, the reflective structure is a cavity, the cavity exposes at least a portion of the surface of the first electrode layer away from the second electrode layer, the third electrode layer in the FBAR is in contact with the outside air, and the first electrode layer is in contact with the cavity.

[0057] In other embodiments, the resonator may be an SMR, the reflective structure may be a Bragg structure, the Bragg structure may include alternately stacked layers of different acoustic impedance materials, and the Bragg structure may be disposed between the substrate and the first electrode layer in the resonant functional structure. Figure 1 No cavity or Bragg structure is shown.

[0058] In some embodiments, the resonator 100 further includes: a Bragg structure disposed between the substrate 102 and the resonant functional structure 104, in which case the resonator 100 is an SMR; or a cavity exposing at least a portion of the surface of the first electrode layer away from the second electrode layer, in which case the resonator 100 is an FBAR.

[0059] Here, according to different methods of forming the cavity, FBAR can be divided into air gap type and back etching type. In some embodiments, when the resonator is an air gap type resonator, a sacrificial layer can be formed on the substrate, a resonant functional structure can be formed on the sacrificial layer, a through hole exposing the sacrificial layer can be formed by etching, and an etching solution is injected through the through hole to remove the sacrificial layer, and a first cavity is formed between the substrate and the first electrode layer. At this time, the substrate and the first electrode layer surround to form a closed first cavity, and the first cavity exposes at least a portion of the surface of the first electrode layer away from the second electrode layer, and the first cavity also exposes a portion of the surface of the substrate close to the first electrode layer.

[0060] In other embodiments, when the resonator is a back-etched resonator, a resonant functional structure may be formed on the substrate, and the back of the substrate may be etched to form a second cavity exposing the resonant functional structure. In this case, the back etching penetrates the substrate along the Z direction, and the second cavity exposes at least a portion of the surface of the first electrode layer away from the second electrode layer, and the second cavity is an open cavity structure.

[0061] In the embodiment of the present disclosure, a first electrode layer 106, a second electrode layer 108, a piezoelectric layer 110 and a third electrode layer 112 are sequentially formed on a substrate 102; wherein the first electrode layer 106 has good electrical conductivity and can achieve good electrical signal connection; the second electrode layer 108 and the piezoelectric layer 110 have the same crystal structure and similar lattice constant, so that the grown piezoelectric layer 110 has a single crystal structure, thereby improving the performance of the resonator 100.

[0062] In some embodiments, the resonator 100 further includes: a buffer layer 114 disposed between the substrate 102 and the resonant functional structure 104 , wherein the buffer layer 114 is used to alleviate the lattice mismatch and thermal mismatch between the substrate 102 and the resonant functional structure 104 .

[0063] Here, "thermal mismatch" in this article refers to the fact that the thermal expansion coefficients of the substrate and the resonant functional structure are different, and the thermal expansion coefficients are quite different, which will cause lattice distortion. The role of the buffer layer is to alleviate the lattice mismatch and thermal mismatch between the substrate and the resonant functional structure, improve the film quality of the resonant functional structure, and thus improve the performance and life of the resonator.

[0064] In some embodiments, the material of the buffer layer 114 includes at least one of aluminum nitride (AlN), gallium nitride (GaN), indium nitride (InN), indium gallium nitride (InGaN), and aluminum gallium nitride (AlGaN).

[0065] refer to Figure 2 , Figure 2 A block diagram of an acoustic wave device provided in an embodiment of the present disclosure. Figure 2 As shown, an embodiment of the present disclosure provides an acoustic wave device, and the acoustic wave device 200 includes: at least one resonator 100 as in the above technical solution.

[0066] In some embodiments, the acoustic wave device 200 may include a filter, a duplexer, and a multiplexer.

[0067] Here, the filter may include at least one resonator, and the resonator may be coupled to the acoustic wave device in series or in parallel. The duplexer may include at least two filters, one filter as a transmitting filter, transmitting an acoustic wave signal, and the other filter as a receiving filter, receiving an acoustic wave signal. The multiplexer may include at least one duplexer and at least one filter.

[0068] The acoustic wave device 200 provided in the embodiment of the present disclosure can be used to process radio frequency signals, including but not limited to radio frequency communication systems such as mobile communications and the Internet of Things that require processing of radio frequency signals.

[0069] refer to Figure 3 , Figure 3 A schematic flow chart of a method for manufacturing a resonator provided in an embodiment of the present disclosure.

[0070] like Figure 3 As shown, an embodiment of the present disclosure provides a method for manufacturing a resonator, the method comprising:

[0071] Step S310: providing a substrate;

[0072] Step S320: forming a resonant functional structure on one side of the substrate, the resonant functional structure comprising a first electrode layer, a second electrode layer, a piezoelectric layer and a third electrode layer stacked in sequence; wherein the distance between the first electrode layer and the substrate is smaller than the distance between the third electrode layer and the substrate, the material of the first electrode layer is different from the material of the second electrode layer, and the lattice matching degree between the piezoelectric layer and the second electrode layer is greater than the lattice matching degree between the piezoelectric layer and the first electrode layer.

[0073] In the embodiment of the present disclosure, in step S310, a substrate is provided.

[0074] Here, before epitaxial growth, a semiconductor cleaning process needs to be performed on the substrate to remove impurities or contaminants on the surface of the substrate, so as to obtain a substrate that is ready for epitaxial growth (Epi-ready). For example, when the substrate material is sapphire, it can be obtained by cleaning with an organic solvent, deionized water, acid, etc.

[0075] In the disclosed embodiment, the material of the substrate includes at least one of sapphire, silicon carbide, silicon and gallium nitride. The resonator obtained by subsequent epitaxial growth based on the substrate has good performance.

[0076] In the embodiment of the present disclosure, before step S320, a buffer layer may be formed on the substrate.

[0077] In some embodiments, the material of the buffer layer includes at least one of aluminum nitride, gallium nitride, indium nitride, indium gallium nitride, and aluminum gallium nitride. Exemplarily, when the material of the buffer layer is indium gallium nitride, the ratio between the indium element and the gallium element can be 1:1, that is, the material of the buffer layer is In 0.5 Ga 0.5 N.

[0078] In the embodiment of the present disclosure, in step S320, a resonant functional structure is formed on one side of the substrate, and the resonant functional structure includes a first electrode layer, a second electrode layer, a piezoelectric layer and a third electrode layer stacked in sequence.

[0079] Here, a first electrode layer is formed on the substrate using a targeted epitaxial growth method, a second electrode layer is formed on the first electrode layer using a targeted epitaxial growth method, a piezoelectric layer is formed on the second electrode layer using a chemical vapor deposition (CVD) process, and a third electrode layer is formed on the piezoelectric layer using a targeted epitaxial growth method.

[0080] In some embodiments, the target epitaxial method includes at least one of the following: physical vapor deposition (PVD), CVD, atomic layer deposition (ALD) and molecular beam epitaxy (MBE).

[0081] In some embodiments, the buffer layer may be grown on the substrate using methods including but not limited to CVD, hydride vapor phase epitaxy (HVPE), ALD or MBE.

[0082] In some embodiments, a chemical vapor deposition process is used to form the piezoelectric layer; the deposition pressure range for forming the piezoelectric layer is 50 torr to 500 torr. Exemplarily, the deposition pressure for forming the piezoelectric layer can be 50 torr, 100 torr, 150 torr, 200 torr, 250 torr, 300 torr, 350 torr, 400 torr, 450 torr or 500 torr; the deposition temperature range is 600°C to 1200°C. Exemplarily, the deposition temperature for forming the piezoelectric layer can be 600°C, 700°C, 800°C, 900°C, 1000°C, 1100°C or 1200°C.

[0083] Compared with the related technical solutions, the piezoelectric layer is formed on the lower electrode layer using the PVD process, and the growth process and the large lattice mismatch problem lead to the piezoelectric layer having a large half-peak width of the rocking curve, poor crystal quality or crystal orientation of the piezoelectric layer, small piezoelectric coefficient of the piezoelectric layer, and poor performance of the resonator. Here, by limiting the use of the CVD process to form the piezoelectric layer, and further limiting the deposition pressure range and deposition temperature range for forming the piezoelectric layer, it is beneficial for the piezoelectric layer to form a single crystal structure, improve the film quality of the piezoelectric layer, and thus improve the performance of the resonator.

[0084] In some embodiments, the substrate and the buffer layer are etched until a portion of the surface of the first electrode layer is exposed, and a second cavity is formed in the substrate, wherein the second cavity exposes a portion of the surface of the first electrode layer away from the second electrode. The size of the second cavity along the Z direction is the sum of the size of the substrate along the Z direction and the size of the buffer layer along the Z direction.

[0085] Example

[0086] A first electrode layer is formed on a sapphire substrate using a targeted epitaxial method, and the material of the first electrode layer is metal molybdenum (Mo); a second electrode layer is formed on the first electrode layer using CVD, and the material of the second electrode layer is niobium nitride (NbN); a piezoelectric layer is formed on the second electrode layer using a CVD process, and the material of the piezoelectric layer is aluminum nitride (AlN); wherein the deposition pressure in the CVD process is 100 torr, and the deposition temperature is 1100°C; a third electrode layer is formed on the piezoelectric layer using a targeted epitaxial method, and the material of the third electrode layer is metal molybdenum (Mo).

[0087] Comparative Example

[0088] A first electrode layer is formed on a sapphire substrate using a targeted epitaxial method, and the material of the first electrode layer is metal molybdenum (Mo); a piezoelectric layer is formed on the first electrode layer using a PVD process, and the material of the piezoelectric layer is aluminum nitride (AlN); a third electrode layer is formed on the piezoelectric layer using a targeted epitaxial method, and the material of the third electrode layer is metal molybdenum (Mo).

[0089] XRD test

[0090] The piezoelectric layers provided in the embodiments and comparative examples were tested. Figure 4 As shown, the horizontal axis is angle (Omega), the unit is arc seconds (arcsec), and the vertical axis is intensity (Intensity), the unit is counts per second (cps). The half-height width of the rocking curve of the X-ray diffraction peak (002) crystal plane of the piezoelectric layer (AlN) provided in the embodiment is 470 arc seconds, and the half-height width of the rocking curve of the X-ray diffraction peak (002) crystal plane of the piezoelectric layer (AlN) provided in the comparative example is 2234 arc seconds. The film quality of the piezoelectric layer (AlN) provided in the embodiment is higher.

[0091] The embodiment of the present disclosure provides a resonator and a method for manufacturing the same. The resonator includes: a substrate and a resonant functional structure arranged on one side of the substrate, the resonant functional structure includes a first electrode layer, a second electrode layer, a piezoelectric layer and a third electrode layer stacked in sequence; wherein the distance between the first electrode layer and the substrate is smaller than the distance between the third electrode layer and the substrate, the material of the first electrode layer is different from the material of the second electrode layer, and the lattice matching degree between the piezoelectric layer and the second electrode layer is greater than the lattice matching degree between the piezoelectric layer and the first electrode layer. Compared with forming a piezoelectric layer on the first electrode layer, the piezoelectric layer and the first electrode layer are in contact, in the embodiment of the present disclosure, the second electrode layer is formed on the first electrode layer, and the piezoelectric layer is formed on the second electrode layer, and the piezoelectric layer and the second electrode layer are in contact. Since the lattice matching degree between the piezoelectric layer and the second electrode layer is greater than the lattice matching degree between the piezoelectric layer and the first electrode layer, the film quality of the piezoelectric layer can be improved, thereby improving the performance of the resonator.

[0092] It should be understood that "one embodiment" or "an embodiment" mentioned throughout the specification means that specific features, structures or characteristics related to the embodiment are included in at least one embodiment of the present disclosure. Therefore, "in one embodiment" or "in an embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. In addition, these specific features, structures or characteristics can be combined in one or more embodiments in any suitable manner. It should be understood that in the various embodiments of the present disclosure, the size of the serial number of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present disclosure. The serial numbers of the embodiments of the present disclosure are for description only and do not represent the advantages and disadvantages of the embodiments.

[0093] The above description is only a preferred embodiment of the present disclosure, and does not limit the patent scope of the present disclosure. All equivalent structural changes made by using the contents of the present disclosure and the drawings under the inventive concept of the present disclosure, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present disclosure.

Claims

1. A resonator, characterized in that: The resonator comprises: A substrate and a resonant functional structure arranged on one side of the substrate, the resonant functional structure comprising a first electrode layer, a second electrode layer, a piezoelectric layer and a third electrode layer stacked in sequence; wherein the distance between the first electrode layer and the substrate is smaller than the distance between the third electrode layer and the substrate, the material of the first electrode layer is different from the material of the second electrode layer, and the lattice matching degree between the piezoelectric layer and the second electrode layer is greater than the lattice matching degree between the piezoelectric layer and the first electrode layer.

2. The resonator according to claim 1, characterized in that The crystal structure of the piezoelectric layer is the same as the crystal structure of the second electrode layer; The absolute value of the ratio of the difference between the lattice constant of the piezoelectric layer and the lattice constant of the second electrode layer to the lattice constant of the piezoelectric layer is less than 5%; and / or the absolute value of the ratio of the difference between the lattice constant of the piezoelectric layer and the lattice constant of the second electrode layer is less than 5%.

3. The resonator according to claim 1, characterized in that The piezoelectric layer is a single crystal structure; the half-peak width of the rocking curve of the piezoelectric layer in X-ray diffraction is less than 0.5 degrees.

4. The resonator according to claim 1, characterized in that The conductivity of the first electrode layer is greater than that of the second electrode layer.

5. The resonator according to claim 1, characterized in that The size of the first electrode layer along the stacking direction is greater than the size of the second electrode layer along the stacking direction; The size of the first electrode layer along the stacking direction ranges from 50 nm to 200 nm, and the size of the second electrode layer along the stacking direction ranges from 10 nm to 100 nm.

6. The resonator according to claim 1, characterized in that The resonator further comprises: a first cavity provided between the substrate and the resonant functional structure, wherein the first cavity exposes at least a portion of a surface of the first electrode layer away from the second electrode layer; or a second cavity provided in the substrate, wherein the second cavity exposes at least a portion of a surface of the first electrode layer away from the second electrode layer; or, A Bragg structure is provided between the substrate and the resonant functional structure.

7. The resonator according to claim 1, characterized in that The material of the piezoelectric layer includes at least one of aluminum nitride, gallium nitride, scandium nitride, aluminum scandium nitride, gallium scandium nitride, indium scandium nitride, aluminum gallium scandium nitride and aluminum gallium scandium indium nitride, wherein the content of scandium in aluminum scandium nitride, gallium scandium nitride, indium scandium nitride, aluminum gallium scandium nitride and aluminum gallium scandium indium nitride is greater than or equal to 1 at%; The material of the first electrode layer includes metal, and the metal includes at least one of molybdenum, platinum, ruthenium, rhodium, gold, iridium, aluminum, titanium, tungsten, palladium, tantalum, chromium and nickel; The material of the second electrode layer includes metal nitride, and the metal nitride includes at least one of niobium nitride, tantalum nitride, hafnium nitride and zirconium nitride.

8. The resonator according to claim 1, characterized in that The resonator further comprises: A buffer layer provided between the substrate and the resonant functional structure, the buffer layer being used to alleviate lattice mismatch and thermal mismatch between the substrate and the resonant functional structure; The material of the buffer layer includes at least one of aluminum nitride, gallium nitride, indium nitride, indium gallium nitride and aluminum gallium nitride.

9. A method for manufacturing a resonator, characterized in that: The method comprises: providing a substrate; A resonant functional structure is formed on one side of the substrate, and the resonant functional structure includes a first electrode layer, a second electrode layer, a piezoelectric layer and a third electrode layer stacked in sequence; wherein the distance between the first electrode layer and the substrate is smaller than the distance between the third electrode layer and the substrate, the material of the first electrode layer is different from the material of the second electrode layer, and the lattice matching degree between the piezoelectric layer and the second electrode layer is greater than the lattice matching degree between the piezoelectric layer and the first electrode layer.

10. The manufacturing method according to claim 9, characterized in that: The piezoelectric layer is formed by using a chemical vapor deposition process; the deposition pressure range of the piezoelectric layer is 50 torr to 500 torr, and the deposition temperature range is 600° C. to 1200° C.

Images