Thin film bulk acoustic resonator and method of manufacturing the same

Abstract

The present application relates to a kind of film bulk acoustic resonator and its manufacturing method, wherein, film bulk acoustic resonator includes: first substrate and support layer being arranged on first substrate, first cavity is equipped in support layer;Piezoelectric laminated structure covers first cavity, piezoelectric laminated structure includes first electrode, piezoelectric layer and second electrode sequentially stacked;First groove is arranged on piezoelectric laminated structure, and it is passed through first electrode and piezoelectric layer, first groove is communicated with first cavity;Second groove is arranged on piezoelectric laminated structure, and it is passed through second electrode and piezoelectric layer;The area surrounded by first groove and second groove is effective resonance area of resonator;Dielectric layer is arranged in first groove and / or second groove.The present application is filled with dielectric layer in groove, to form support with the electrode of the area where groove is located, to strengthen the firmness of device structure, avoid resonator structure damage, in addition, also form acoustic impedance mismatch, to prevent acoustic wave leakage.

Description

Technical Field

[0001] This invention relates to the field of semiconductor device manufacturing, and in particular to a thin-film bulk acoustic resonator and its manufacturing method. Background Technology

[0002] Since the development of analog radio frequency (RF) communication technology in the early 1990s, RF front-end modules have gradually become core components of communication equipment. Among all RF front-end modules, filters have become the fastest-growing and most promising component. With the rapid development of wireless communication technology and the increasing maturity of 5G communication protocols, the market has also set more stringent standards for the performance of RF filters. The performance of a filter is determined by the resonator units that make up the filter. Among existing filters, thin-film bulk acoustic resonators (FBARs) have become one of the most suitable filters for 5G applications due to their small size, low insertion loss, high out-of-band rejection, high quality factor, high operating frequency, large power capacity, and good ESD resistance.

[0003] Typically, a thin-film bulk acoustic resonator includes two thin-film electrodes with a piezoelectric thin-film layer between them. Its working principle involves the piezoelectric thin-film layer vibrating under an alternating electric field. This vibration excites a bulk acoustic wave propagating along the thickness of the piezoelectric thin-film layer. This acoustic wave is reflected back at the interface between the upper and lower electrodes and the air, and then reflects back and forth within the thin film, creating oscillations. When the acoustic wave propagates within the piezoelectric thin-film layer for an odd multiple of half its wavelength, a standing wave oscillation is formed.

[0004] However, the currently fabricated thin-film bulk acoustic resonators rely entirely on a single piezoelectric film for support after the piezoelectric layer is grooved. This makes them highly susceptible to structural breakage during the manufacturing process, resulting in low yield and poor quality factor. Furthermore, their quality factor (Q) cannot be further improved, thus failing to meet the requirements of high-performance radio frequency systems. Summary of the Invention

[0005] The purpose of this invention is to provide a thin-film bulk acoustic resonator and its manufacturing method, which can enhance the robustness of the device structure, avoid damage to the resonator structure, and thus improve the device performance.

[0006] To achieve the above objectives, the present invention provides a thin-film bulk acoustic resonator, comprising:

[0007] A first substrate and a support layer disposed on the first substrate, wherein the support layer has a first cavity;

[0008] A piezoelectric stacked structure covers the first cavity. The piezoelectric stacked structure includes a first electrode, a piezoelectric layer, and a second electrode stacked sequentially.

[0009] A first trench is arranged on the piezoelectric layer structure and penetrates the first electrode and the piezoelectric layer, and the first trench is in communication with the first cavity;

[0010] A second trench is arranged on the piezoelectric layer structure and penetrates the second electrode and the piezoelectric layer;

[0011] The area surrounded by the first trench and the second trench is the effective resonant area of the resonator;

[0012] A dielectric layer is arranged in the first trench and / or the second trench.

[0013] The application further provides a manufacturing method of the film bulk acoustic resonator, comprising:

[0014] A temporary substrate is provided;

[0015] A second electrode layer, a piezoelectric layer and a first electrode layer are sequentially formed on the temporary substrate;

[0016] A first trench is formed and penetrates the first electrode layer and the piezoelectric layer;

[0017] A support layer is formed on the first electrode layer, and a first cavity is formed on the support layer to expose part of the first electrode layer;

[0018] The first substrate is bonded on the support layer, and the first substrate covers the first cavity;

[0019] The temporary substrate is removed;

[0020] A second trench is formed and penetrates the second electrode layer and the piezoelectric layer, and the area surrounded by the first trench and the second trench is the effective resonant area of the resonator;

[0021] Before the first substrate is bonded, a dielectric layer is formed in the first trench; and / or, after the second trench is formed, a dielectric layer is formed in the second trench.

[0022] The application has the following beneficial effects:

[0023] The film bulk acoustic resonator provided by the application forms the first trench and the second trench, and arranges the dielectric layer in the first trench and / or the second trench, so that the electrode in the area where the trench is located and the dielectric layer together form a support, thereby strengthening the firmness of the device structure, avoiding damage to the resonator structure, protecting the device structure, improving the device performance, and in addition, arranging the dielectric layer in the trench can also make the resonant area of the resonator and the area where the trench is located form an acoustic impedance mismatch, prevent acoustic wave leakage, and improve the quality factor.

[0024] Further, the outer periphery of the first dielectric layer is in contact with the sidewall of the first groove, and the outer periphery of the second dielectric layer is in contact with the sidewall of the second groove, so as to ensure the firmness of the structure, thereby improving the device performance; in addition, the lower surface of the first dielectric layer is flush with the lower surface of the first electrode, so that the first electrode and the first dielectric layer in the area where the first groove is located can form support, and the upper surface of the second dielectric layer is flush with the lower surface of the second electrode, so that the second electrode and the second dielectric layer in the area where the second groove is located can form support, thereby strengthening the firmness of the device structure and improving the device performance.

[0025] Further, by setting the acoustic impedance ratio of the dielectric layer material to the piezoelectric layer material, the dielectric layer and the piezoelectric layer have a large acoustic impedance ratio, thereby forming an acoustic impedance mismatch, and effectively suppressing the acoustic wave.

[0026] Further, by etching the air hole, the internal and external pressures of the first cavity can be balanced.

[0027] Further, by making the first electrode and the second electrode outside the effective resonance area have no overlapping area in the direction perpendicular to the piezoelectric layer, it is avoided that after the first electrode and the second electrode are connected to high-frequency signals, the first electrode or the second electrode generates a potential floating in the non-effective resonance area, thereby avoiding high-frequency coupling between the first electrode and the second electrode located thereon or between the second electrode and the first electrode located thereunder, and avoiding the generation of interference signals to affect the quality factor (Q) of the device, so as to improve the device performance.

[0028] The manufacturing method of the thin film bulk acoustic resonator provided by the application forms a dielectric layer in the first groove and / or the second groove to support the first electrode and / or the second electrode at the groove, thereby strengthening the firmness of the device structure and avoiding damage to the resonator structure; the first groove and the second groove are formed by a double-sided process, the piezoelectric layer can be smoothly formed, the integrity and flatness of the piezoelectric layer are ensured, the influence on the piezoelectric layer is reduced, thereby improving the performance of the resonator, and the method is compatible with the main process of the resonator, the process is simple, and the effective resonance area is effectively protected; the first groove and the second groove formed by the method enclose the effective resonance area to suppress the energy leakage of the acoustic wave.

[0029] Further, by forming a dielectric layer and then etching the dielectric layer, the first dielectric layer, the support layer and the first cavity are formed at the same time, thereby saving process steps and improving production efficiency.

[0030] Further, by setting the isolation layer, the first electrode and the first dielectric material layer are isolated, so as to avoid etching the first dielectric layer located in the first groove when forming the first cavity, thereby avoiding damaging the flatness of the surface of the first dielectric layer and the surface of the first electrode layer, and further improving the firmness of the device structure.

[0031] Further, by setting the etching stop layer, the second electrode and the second dielectric material layer can be isolated, so that the flatness of the surface of the second dielectric layer over the surface of the second electrode layer is avoided from being damaged when the second dielectric layer is formed by removing the excess second dielectric material layer, and the firmness of the device structure is further improved. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0033] Figure 1 for the cross-sectional structure along Figure 1A the A-A line;

[0034] Figure 1A a top view of a film bulk acoustic resonator provided by an embodiment of the present application;

[0035] Figure 2 a cross-sectional structure schematic diagram of a film bulk acoustic resonator provided by another example;

[0036] Figure 3 a flowchart of a manufacturing method of a film bulk acoustic resonator provided by an embodiment of the present application;

[0037] Figures 4-11 for the cross-sectional structure along Figure 1A the A-A line;

[0038] Explanation of reference signs:

[0039] 1, first substrate; 2, support layer; 21, first cavity; 3, piezoelectric laminated structure; 31, first electrode; 31', first electrode layer; 32, piezoelectric layer; 33, second electrode; 33', second electrode layer; 4, first trench; 5, second trench; 6, dielectric layer; 61, first dielectric layer; 62, second dielectric layer; 7, isolation layer; 8, air hole; 9, temporary substrate; 101, first pad; 102, second pad. DETAILED DESCRIPTION

[0040] At present, the cavity type film bulk acoustic resonator made has the problems of acoustic wave loss, insufficient structural strength, inability to further improve the quality factor (Q), low yield, and the like, and thus cannot meet the demand of high-performance radio frequency systems.

[0041] To solve the above problems, the application provides a film bulk acoustic resonator, which fills a medium layer in a groove to form a support together with an electrode in a region where the groove is located, thereby strengthening the firmness of the device structure, avoiding damage to the resonator structure, protecting the device structure, and improving the device performance.

[0042] The film bulk acoustic resonator and the manufacturing method thereof of the application will be further described in detail below in combination with the drawings and specific embodiments. According to the following description and drawings, the advantages and features of the application will be more apparent, however, it should be noted that the technical solutions of the application can be implemented in various different forms and are not limited to the specific embodiments described herein. The drawings all adopt a very simplified form and use non-precise proportions, which are only used to facilitate and clarify the purpose of assisting in the description of the embodiments of the application.

[0043] The terms "first", "second", and the like in the description and claims are used to distinguish between like elements, and are not necessarily used to describe a particular sequential or chronological order. It is to be understood that, where appropriate, the terms so used can be interchangeable, such that the embodiments of the application described herein can operate in other sequences than described or illustrated herein. Similarly, if a method is described herein as comprising a series of steps, the order in which such steps are presented is not necessarily the only order in which such steps can be performed, and some of the steps can be omitted and / or other steps can be added to the method. If components in a figure are the same as components in other figures, although these components can be easily recognized in all the figures, the description will not mark the same components with the same reference numerals in each figure in order to make the description of the figures clearer.

[0044] Figure 1A A top view of a film bulk acoustic resonator provided for an embodiment of the application, Figure 1 A top view of a film bulk acoustic resonator provided for an embodiment of the application, Figure 1A A cross-sectional structure schematic view of a film bulk acoustic resonator along A-A is shown in Figure 1A A cross-sectional structure schematic view of a film bulk acoustic resonator along A-A is shown in Figure 1 The film bulk acoustic resonator comprises:

[0045] A first substrate 1 and a support layer 2 arranged on the first substrate 1, wherein the support layer 2 is provided with a first cavity 21;

[0046] A piezoelectric layer structure 3 covering the first cavity 21, wherein the piezoelectric layer structure 3 comprises a first electrode 31, a piezoelectric layer 32, and a second electrode 33 which are sequentially stacked;

[0047] A first groove 4 arranged on the piezoelectric layer structure 3 and penetrating through the first electrode 31 and the piezoelectric layer 32, wherein the first groove 4 is in communication with the first cavity 21;

[0048] a second trench 5 provided on the piezoelectric layer structure 3 and extending through the second electrode 33 and the piezoelectric layer 32;

[0049] The area surrounded by the first trench 4 and the second trench 5 is the effective resonant area of the resonator.

[0050] a dielectric layer 6 provided in the first trench 4 and / or the second trench 5.

[0051] The first substrate 1 can be any suitable substrate known to those skilled in the art, for example, it can be at least one of the following materials: silicon (Si), germanium (Ge), silicon-germanium (SiGe), silicon-carbon (SiC), silicon-germanium-carbon (SiGeC), indium arsenide (InAs), gallium arsenide (GaAs), indium phosphide (InP) or other III / V compound semiconductors, including multi-layer structures formed by these semiconductors, etc., or silicon-on-insulator (SOI), silicon-on-silicon-on-insulator (SSOI), silicon-germanium-on-insulator (SiGeOI), and germanium-on-insulator (GeOI), or double side polished wafers (DSP), ceramic substrates such as aluminum oxide, quartz or glass substrates, etc. In the embodiment, the material of the first substrate 1 is a <100> crystal orientation P-type high resistance single crystal silicon wafer.

[0052] The support layer 2 is provided on the first substrate 1, and the first cavity 21 is provided in the support layer 2. It should be noted that the support layer 2 can be combined with the first substrate 1 by bonding or deposition. The deposition method can be chemical vapor deposition or physical vapor deposition. The bonding method includes thermal compression bonding or dry film bonding. The first substrate 1 and the support layer 2 can also be bonded by a bonding layer, and the material of the bonding layer includes silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride or ethyl silicate. In addition, the bonding layer can also use light-cured materials or heat-cured materials such as adhesives, for example, die attach film (DAF) or dry film. In other embodiments, the bonding method can also include covalent bonding, adhesive bonding or fusion bonding. The material of the support layer 2 can be the same as the material of the first substrate 1, or any suitable dielectric material, including but not limited to one of the following materials: silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, etc. In other embodiments, the first cavity 21 is not limited to being provided in the support layer 2, and the first cavity 21 can also be formed directly in the first substrate 1 without the support layer 2, and the piezoelectric layer structure 3 is directly provided on the first substrate.

[0053] In this embodiment, the cross section of the first cavity 21 is rectangular, but in other embodiments of the present application, the cross section of the first cavity 21 can also be circular, elliptical, or polygonal other than rectangular, such as pentagonal, hexagonal, etc. The first cavity 21 can be formed by etching the support layer.

[0054] The first cavity 21 is provided with a piezoelectric layer structure 3 above the first cavity 21, and an isolation layer 7 is provided between the piezoelectric layer structure 3 and the support layer 2. The first cavity 21 penetrates the support layer 2 and the isolation layer 7 to communicate with the first groove 4, or the first cavity 21 penetrates the support layer 2 to isolate the first cavity 21 from the first groove 4. When the first cavity 21 penetrates the support layer 2 and the isolation layer 7, the sound wave can be prevented from leaking from the isolation layer 7, thereby better suppressing the sound wave.

[0055] The material of the isolation layer 7 includes but is not limited to silicon oxide, silicon nitride, or silicon oxynitride. On the one hand, the isolation layer 7 can be used to increase the structural stability of the finally manufactured film bulk acoustic resonator, and on the other hand, the isolation layer 7 has a lower etching rate than the support layer 2, which can prevent over-etching during the etching of the support layer 2 to form the first cavity 21, thereby protecting the surface of the first electrode 31 below from damage, thereby improving the performance and reliability of the device. In addition, if the material of the dielectric layer 6 in the first groove 4 is the same as that of the support layer 2, the isolation layer 7 can also prevent etching damage to the dielectric layer 6 in the first groove 4. In other embodiments, the piezoelectric layer structure 3 is directly provided on the support layer 2 and covers the first cavity 21.

[0056] The piezoelectric layer structure 3 includes a first electrode 31, a piezoelectric layer 32, and a second electrode 33. The first electrode 31 is located on the support layer 2. The piezoelectric layer 32 is located on the first electrode 31, and the second electrode 33 is located on the piezoelectric layer 32. The first electrode 31 and the second electrode 33 respectively serve as receiving or providing electrical signals such as radio frequency (RF) signals. When the first electrode 31 and the second electrode 33 are connected to alternating current, the first electrode 31 and the second electrode 33 are in a dynamic change process. It should be noted that the first electrode 31 includes an edge region not covered by the piezoelectric layer 32 and the second electrode 33, so as to facilitate the subsequent input / output of electrical signals.

[0057] In this embodiment, the first electrode 31 located outside the first cavity 21 is provided on the isolation layer 7, so as to support the piezoelectric layer structure 3. It should be noted that the shapes of the second electrode 33 and the first electrode 31 can be the same or different.

[0058] The first electrode 31, the second electrode 33 and the piezoelectric layer 32 outside the effective resonance region do not overlap each other in the direction perpendicular to the surface of the piezoelectric layer 32, thereby avoiding the problem of high frequency coupling caused by potential floating, and facilitating the improvement of the Q value of the resonator.

[0059] Generally, the second electrode 33 and the first electrode 31 can use any suitable conductive material or semiconductor material known to those skilled in the art, wherein the conductive material can be a metal material having conductive properties, such as one made of molybdenum (Mo), aluminum (Al), copper (Cu), tungsten (W), tantalum (Ta), platinum (Pt), ruthenium (Ru), rhodium (Rh), iridium (Ir), chromium (Cr), titanium (Ti), gold (Au), osmium (Os), rhenium (Re), palladium (Pd) or a stack formed by the above-mentioned metals, and the semiconductor material is, for example, Si, Ge, SiGe, SiC, SiGeC, etc. The second electrode 33 and the first electrode 31 can be formed by physical vapor deposition such as magnetron sputtering, evaporation or chemical vapor deposition.

[0060] The material of the piezoelectric layer 32 can use a piezoelectric material having a wurtzite crystal structure such as aluminum nitride (AIN), zinc oxide (ZnO), lead zirconate titanate (PZT), lithium niobate (LiNbO3), quartz, potassium niobate (KNbO3) or lithium tantalate (LiTaO3), or a combination thereof. When the piezoelectric layer 32 includes aluminum nitride (AIN), the piezoelectric layer 32 can further include at least one of rare earth metals such as scandium (Sc), erbium (Er), yttrium (Y) and lanthanum (La). In addition, when the piezoelectric layer 32 includes aluminum nitride (AIN), the piezoelectric layer 32 can further include at least one of transition metals such as zirconium (Zr), titanium (Ti), manganese (Mn) and hafnium (Hf). The piezoelectric layer 32 can be deposited by any suitable method known to those skilled in the art such as chemical vapor deposition, physical vapor deposition or atomic layer deposition. In the present embodiment, the second electrode 33 and the first electrode 31 are made of metallic molybdenum (Mo), and the piezoelectric layer 32 is made of aluminum nitride (AIN).

[0061] The first trench 4 and the second trench 5, also called air trench, are arranged in the piezoelectric layer structure 3, the first trench 4 penetrates the first electrode 31 and the piezoelectric layer 32 and communicates with the first cavity 21, and the second trench 5 penetrates the second electrode 33 and the piezoelectric layer 32. In the embodiment, since the isolation layer 7 is arranged between the support layer 2 and the first electrode 31, the first trench 4 penetrates the piezoelectric layer 32, the first electrode 33 and the isolation layer 7. It should be noted that the first trench 4 exposes the part of the surface of the second electrode 33, the part of the side of the piezoelectric layer 32 and the part of the side of the first electrode 31 to the air, the material of the piezoelectric layer 2 and the material of the electrode have a large acoustic impedance mismatch with the air, the acoustic wave in the piezoelectric layer structure 3 is reflected at the air interface, and the energy leakage of the acoustic wave is prevented. Similarly, the second trench 5 also prevents the energy leakage of the acoustic wave.

[0062] The area surrounded by the first trench 4 and the second trench 5 is the effective resonance area of the resonator, and the effective resonance area is defined by the first trench 4 and the second trench 5, so that the area where the first trench 4 and the second trench 5 are located forms an acoustic impedance mismatch, thereby effectively suppressing the acoustic wave. The first trench 4 and / or the second trench 5 are at least partially located in the range of the first cavity 21, the first trench 4 communicates with the first cavity 21, so that the effective resonance area surrounded by the first trench 4 and the second trench 5 is located above the first cavity 21, so as to facilitate the longitudinal propagation of the acoustic wave in the effective resonance area to the first cavity 21 or the air above the second electrode 33, and due to the acoustic impedance mismatch between the air and the electrode material, the acoustic wave is reflected back to the effective resonance area, thereby improving the effective utilization rate of the acoustic wave. When the first trench 4 and the second trench 5 are all located in the range of the first cavity 21, the effective utilization rate of the acoustic wave in the effective resonance area is best.

[0063] The projection of the first trench 4 on the plane where the piezoelectric layer 32 is located is a semicircle or a polygon similar to a semicircle; and / or, the projection of the second trench 5 on the plane where the piezoelectric layer 32 is located is a semicircle or a polygon similar to a semicircle. In the embodiment, the projection of the effective resonance area on the plane where the piezoelectric layer 32 is located is a polygon, and any two edges of the polygon are not parallel. In addition, the first trench 4 and the second trench 5 are arranged along the A-A line in the plane where the piezoelectric layer 32 is located. Figure 1A The cross section of the first trench 4 and the second trench 5 along the A-A line is a trapezoid or a trapezoid-like shape, that is, the angle α between the first trench 4 and the plane where the second electrode 33 is located, and the angle β between the side wall of the second trench 5 and the plane where the first electrode 31 is located, α and β are obtuse angles, and further, α and β are greater than 90 degrees and less than 160 degrees. In other embodiments, the shape of the cross section of the effective resonance area is a circle.

[0064] Since the first groove 4 and the second groove 5 define the range of the effective resonance area, the first groove 4 and the second groove 5 are located at the periphery of the effective resonance area, and the projection of the first groove 4 and the second groove 5 on the plane where the piezoelectric layer 32 is located can be evenly divided into a ring formed by the combination of the two, and in this case, the first groove 4 and the second groove 5 are located on both sides of the effective resonance area and are completely opposite to each other. In other embodiments, the projection of the first groove 4 and the second groove 5 on the plane where the piezoelectric layer 32 is located can also be unevenly divided into a ring formed by the combination of the two, and in this case, the first groove 4 and the second groove 5 are located on both sides of the effective resonance area and are only partially opposite to each other.

[0065] The projection of the first groove 4 and the second groove 5 on the plane where the piezoelectric layer 32 is located can be exactly connected or nearly connected, that is, the projection of the first groove 4 and the second groove 5 on the plane where the piezoelectric layer 32 is located can form a completely closed ring or a nearly closed ring. In this embodiment, the projection of the first groove 4 and the second groove 5 on the plane where the piezoelectric layer 32 is located forms a continuous closed ring, and any two sides of the polygon are not parallel. In other embodiments, the first groove 4 includes a plurality of first sub-grooves; and / or, the second groove 5 includes a plurality of second sub-grooves, and the projection of the plurality of first sub-grooves and the plurality of second sub-grooves on the plane where the piezoelectric layer 32 is located can form a discontinuous nearly closed pentagon.

[0066] In some embodiments, since the first groove 4 and the second groove 5 can define the effective resonance area, other areas of the first electrode 31, the piezoelectric layer 32 and the second electrode 33 can also not be patterned, that is, the three-layer structure is flat, the formed structure has better quality, there is no other area with mismatched acoustic impedance except the groove, which can increase the resonance quality factor.

[0067] The dielectric layer 6 is arranged in the first groove 4 and / or the second groove 5, and the material of the dielectric layer 6 has different acoustic impedance from the material of the piezoelectric layer 32, so as to form an acoustic impedance mismatch and effectively suppress the acoustic wave. When the dielectric layer 6 is located in the first groove 4 and the second groove 5 at the same time, the effect of suppressing the acoustic wave is best. The material of the dielectric layer 6 includes one or a combination of several of silicon dioxide, silicon nitride, aluminum oxide and aluminum nitride.

[0068] Specifically, the outer periphery of the medium layer 6 arranged in the first groove 4 is in contact with the sidewall of the first groove 4; and / or, the outer periphery of the medium layer 6 arranged in the second groove 5 is in contact with the sidewall of the second groove 5. It is to be noted that, taking the medium layer 6 arranged in the first groove 4 as an example, the outer periphery of the medium layer 6 can be in contact with the sidewall of the first groove 4 or there can be a gap. In addition, when the medium layer 6 is arranged in the first groove 4, the medium layer 6 can or can not be arranged in the second groove 5, and when the medium layer 6 is arranged in the second groove 5, the outer periphery of the medium layer 6 can be in contact with the sidewall of the second groove 5 or there can be a gap. The case of arranging the medium layer 6 in the second groove 5 is similar to the case of arranging the medium layer 6 in the first groove 4, which will not be described here again. When the outer periphery of the medium layer 6 arranged in the first groove 4 is in contact with the sidewall of the first groove 4, and the outer periphery of the medium layer 6 arranged in the second groove 5 is in contact with the sidewall of the second groove 5, the firmness of the device structure can be enhanced, and the supporting effect is the best, and the device structure is the most stable.

[0069] In addition, the first surface of the medium layer 6 arranged in the first groove 4 is flush with the first surface of the first electrode 31; and / or, the first surface of the medium layer 6 arranged in the second groove 5 is flush with the first surface of the second electrode 33. When the medium layer 6 is arranged in the first groove 4, the first surface of the medium layer 6 can be higher, lower or flush with the first surface of the first electrode 31, and in this case, the medium layer 6 can or can not be arranged in the second groove 5, and when the medium layer 6 is arranged in the second groove 5, the first surface of the medium layer 6 can be higher, lower or flush with the first surface of the second electrode 33. Similarly, the medium layer 6 can also be arranged only in the second groove 5, and the case is similar to the case of arranging the medium layer 6 in the first groove 4, which will not be described here again.

[0070] It is to be noted that, when the first surface of the medium layer 6 arranged in the first groove 4 is flush with the first surface of the first electrode 31, and the first surface of the medium layer 6 arranged in the second groove 5 is flush with the first surface of the second electrode 33, the electrodes in the regions where the first groove 4 and the second groove 5 are located can form a support together with the medium layer 6, and the firmness of the device structure can be enhanced, so that the device structure is not damaged, the purpose of protecting the device structure is achieved, and the device performance is improved. In addition, the first surface of the first electrode 31 is the surface in contact with the isolation layer 7, the first surface of the medium layer 6 arranged in the first groove 4 is the surface close to the first surface of the first electrode 31, the first surface of the second electrode 33 is the surface opposite to the contact surface of the piezoelectric layer 32, and the first surface of the medium layer 6 arranged in the second groove 5 is the surface close to the first surface of the second electrode 33.

[0071] The medium layer 6 is a continuous whole, and a projection of the medium layer 6 on the surface of the piezoelectric layer 32 is a ring, a semi-ring or a polygon; or the medium layer 6 includes a plurality of discontinuously arranged sub-medium layers, and a projection of the medium layer 6 on the surface of the piezoelectric layer 32 is a ring, a semi-ring or a polygon with gaps. It should be noted that the polygon can be a polygon similar to the ring or the semi-ring. In the embodiment, the shape of the medium layer 6 is matched according to the shape of the groove in which the medium layer 6 is located, for example, the medium layer 6 is formed in the first groove 4, and the shape of the medium layer 6 is the same as the shape of the first groove 4.

[0072] Specifically, the medium layer 6 includes a first medium layer 61 and a second medium layer 62, the first medium layer 61 is arranged in the first groove 4, and the second medium layer 62 is arranged in the second groove 5. The first medium layer 61 is a continuous whole or includes a plurality of discontinuously arranged first sub-medium layers; and / or the second medium layer 62 is a continuous whole or includes a plurality of discontinuously arranged second sub-medium layers. The projections of the first medium layer 61 and the second medium layer 62 on the surface of the piezoelectric layer 32 form a ring that is completely closed or close to closed. It should be noted that when the first medium layer 61 and the second medium layer 62 are both continuous wholes, and the projections of the first medium layer 61 and the second medium layer 62 on the surface of the piezoelectric layer form a closed ring, the support effect of the first medium layer 61 and the second medium layer 62 on the device structure is best.

[0073] Since the first medium layer 61 and the second medium layer 62 are respectively located in the first groove 4 and the second groove 5, the area of the region surrounded by the projections of the first medium layer 61 and the second medium layer 62 on the plane of the piezoelectric layer 32 is not greater than the area of the region surrounded by the projections of the first groove 4 and the second groove 5 on the plane of the piezoelectric layer 32.

[0074] In order to keep the pressure inside and outside the first cavity 21 balanced, the piezoelectric layer structure 3 is further provided with a gas permeable hole 8 which penetrates the piezoelectric layer structure 3 to communicate with the first cavity 21.

[0075] In order to facilitate the input or output of electrical signals to the first electrode 31 and the second electrode 33, the film bulk acoustic resonator can include a signal input / output structure. For example, the signal input / output structure is a first pad 101 and a second pad 102 connected to the first electrode 31 and the second electrode 33 respectively. Specifically, the first pad 101 is connected to the edge region of the first electrode 31 which is not covered by the piezoelectric layer 32 and the second electrode 33, and the second pad 102 is connected to the edge region of the second electrode 33.

[0076] In addition, in order to avoid the pollution of the layers exposed to the upper space by the external environment, a top cover is further arranged above the piezoelectric laminated structure 3, the top cover has a second cavity, the second cavity is located above the first cavity 21, and the second groove 5 is at least partially located in the second cavity. Specifically, the top cover comprises a bonding layer and a second substrate, the second cavity is formed on the bonding layer, the second cavity can or can not penetrate the bonding layer, and the second substrate is bonded above the bonding layer. The bonding layer can be made of silicon oxide, silicon nitride, silicon oxynitride, ethyl silicate, or an adhesive such as a light-cured material or a heat-cured material, for example, a die attach film (DF) or a dry film. The material of the bonding layer and the material of the second substrate can be the same, and the two are an integral structure, that is, the top cover is an integral structure, and the second cavity is formed by forming a space in the top cover.

[0077] In summary, the thin film bulk acoustic resonator provided by the present application forms a first groove and a second groove, and a dielectric layer is arranged in the first groove and / or the second groove, so that the electrode in the area where the groove is located and the dielectric layer together form a support, thereby strengthening the firmness of the device structure, avoiding damage to the resonator structure, protecting the device structure, and improving the device performance. In addition, the arrangement of the dielectric layer in the groove can also form an acoustic impedance mismatch between the resonant region of the resonator and the area where the groove is located, prevent acoustic wave leakage, and improve the quality factor.

[0078] Further, the outer periphery of the first dielectric layer is in contact with the side wall of the first groove, and the outer periphery of the second dielectric layer is in contact with the side wall of the second groove, so as to ensure the firmness of the structure and thereby improve the device performance. In addition, the lower surface of the first dielectric layer is flush with the lower surface of the first electrode, so that the first electrode in the area where the first groove is located and the first dielectric layer form a support, and the upper surface of the second dielectric layer is flush with the lower surface of the second electrode, so that the second electrode in the area where the second groove is located and the second dielectric layer form a support, thereby strengthening the firmness of the device structure and improving the device performance.

[0079] Further, by setting the acoustic impedance ratio of the dielectric layer material to the piezoelectric layer material, the dielectric layer and the piezoelectric layer have a large acoustic impedance ratio, thereby forming an acoustic impedance mismatch, and effectively suppressing the acoustic wave.

[0080] Further, by etching the air hole, the internal and external pressures of the first cavity can be balanced.

[0081] Further, by making the first electrode and the second electrode outside the effective resonance area have no overlapping area in the direction perpendicular to the piezoelectric layer, the first electrode or the second electrode is prevented from floating in potential in the non-effective resonance area after the first electrode and the second electrode are connected to the high-frequency signal, thereby preventing the first electrode and the second electrode on or under the first electrode from being coupled at high frequency, and further preventing the generation of interference signals to affect the quality factor (Q) of the device, so as to improve the performance of the device.

[0082] Figure 3 A flow chart of steps of a manufacturing method of a film bulk acoustic resonator according to an embodiment of the present application is shown in Figure 3 The manufacturing method of the film bulk acoustic resonator comprises the following steps.

[0083] S01: providing a temporary substrate;

[0084] S02: sequentially forming a second electrode layer, a piezoelectric layer and a first electrode layer on the temporary substrate;

[0085] S03: forming a first trench penetrating the first electrode layer and the piezoelectric layer;

[0086] S04: forming a support layer on the first electrode layer, and forming a first cavity on the support layer to expose part of the first electrode layer;

[0087] S05: bonding a first substrate on the support layer, the first substrate covering the first cavity;

[0088] S06: removing the temporary substrate;

[0089] S07: forming a second trench penetrating the second electrode layer and the piezoelectric layer, the area surrounded by the first trench and the second trench being an effective resonance area of the resonator;

[0090] S08: before the bonding of the first substrate, forming a dielectric layer in the first trench; and / or, after the forming of the second trench, forming a dielectric layer in the second trench.

[0091] Figures 4 to 11 A corresponding cross-sectional structure schematic diagram of the corresponding steps of a manufacturing method of a film bulk acoustic resonator according to the embodiment along A-A in Figure 1A The manufacturing method of the film bulk acoustic resonator provided by the embodiment will be described in detail below with reference to Figures 4 to 11

[0092] Referring to Figure 4 S01 is performed to provide a temporary substrate 9.

[0093] The material of the temporary substrate 9 can refer to the material of the first substrate in the structural embodiment, which will not be described herein again.

[0094] ​In addition, an insulating layer can be formed on the temporary substrate 9 to facilitate subsequent peeling of the temporary substrate 9. In a subsequent peeling process, the temporary substrate 9 can be separated from the second electrode layer 33' formed subsequently by etching the insulating layer, which helps to quickly peel off the temporary substrate 9 and improve the process efficiency. The material of the insulating layer includes, but is not limited to, at least one of silicon dioxide (SiO2), silicon nitride (Si3N4), aluminum oxide (Al2O3), and aluminum nitride (AlN). The insulating layer can be formed by chemical vapor deposition, magnetron sputtering, or evaporation, etc. In the embodiment, the temporary substrate 9 is monocrystalline silicon, and the material of the insulating layer is silicon dioxide (SiO2).

[0095] With reference back to Figure 4 , step S02 is performed to sequentially form the second electrode layer 33', the piezoelectric layer 32, and the first electrode layer 31' on the temporary substrate 9. The piezoelectric layer 32 is located between the first electrode layer 31' and the second electrode layer 33', and the first electrode layer 31' and the second electrode layer 33' are oppositely arranged. It should be noted that when the insulating layer is formed on the temporary substrate 9, the second electrode layer 33' is formed on the insulating layer.

[0096] The first electrode layer 31' is used to form a first electrode subsequently, and the second electrode layer 33' is used to form a second electrode subsequently. The materials of the first electrode layer 31', the second electrode layer 33', and the piezoelectric layer 32 can refer to the materials of the first electrode, the second electrode, and the piezoelectric layer 32 in the structural embodiment part described above, respectively. Specifically, the second electrode layer 33', the piezoelectric layer 32, and the first electrode layer 31' are sequentially formed on the surface of the temporary substrate 9 by a deposition process, so that the second electrode layer 33', the piezoelectric layer 32, and the first electrode layer 31' formed subsequently are kept flat, thereby forming the piezoelectric layer 32 on the flat second electrode layer 33' to ensure that the piezoelectric layer 32 has a good lattice orientation, improve the piezoelectric properties of the piezoelectric layer 32, and further improve the overall performance of the resonator. The formation of the first electrode layer 31' or the second electrode layer 33' can be achieved by physical vapor deposition such as magnetron sputtering, evaporation, or chemical vapor deposition. The formation of the piezoelectric layer 32 can be achieved by any suitable method known to those skilled in the art, such as chemical vapor deposition, physical vapor deposition, or atomic layer deposition.

[0097] Before the second electrode layer 33' is formed, a seed layer can be formed on the insulating layer, the seed layer is formed between the insulating layer and the second electrode layer 33', the seed layer has a guiding effect on the crystal direction of the subsequently formed second electrode layer 33', piezoelectric layer 32 and first electrode layer 31', facilitating the growth of the subsequently formed second electrode, piezoelectric layer 32 and first electrode along a specific crystal direction, and ensuring the uniformity of the piezoelectric layer 32. The material of the seed layer can be aluminum nitride (AlN). In addition to AlN, the seed layer can also be formed by using a metal or a dielectric material having a hexagonal close-packed (HCP) structure. For example, the seed layer can also be formed by titanium (Ti).

[0098] In addition, after the second electrode layer 33', the piezoelectric layer 32 and the first electrode layer 31' are sequentially formed on the temporary substrate, the first electrode layer 31' is patterned to form the first electrode, and the first electrode, the piezoelectric layer 32 and the second electrode layer 33' are flat. Specifically, before or after the first trench is formed, the first electrode layer 31' is patterned, specifically including: coating photoresist on the surface of the first electrode layer 31' to form a photoresist layer, defining a first mask pattern according to the required first electrode pattern, and then exposing it to transfer the first mask pattern structure to the photoresist layer, then developing the photoresist layer, and using the developed photoresist layer as a mask to etch the first electrode layer by a dry etching process to form the first electrode 31, and finally removing the photoresist layer. It should be noted that in the implementation process of patterning the first electrode, the entire region of the first electrode layer 31' except the first electrode can be etched, or only the first electrode and other regions in the first electrode layer 31' can be electrically isolated. Specifically, the boundary of the first mask pattern defined in the first electrode layer 31' can be etched, and the first electrode layer 31' can be etched along the boundary of the first mask pattern to form a gap with a certain line width, and finally the first electrode can be completely separated from the first electrode layer 31', and the other regions in the first electrode layer 31' can be retained to achieve electrical isolation. In this embodiment, the first electrode 31 formed by etching covers the first cavity formed subsequently.

[0099] Reference Figure 5 Step S03 is performed to form the first trench 4, which penetrates the first electrode layer 31' and the piezoelectric layer 32.

[0100] The sidewall of the first trench 4 can be inclined or vertical. In this embodiment, the angle a between the sidewall of the first trench 4 and the plane of the piezoelectric layer 32 is 90 < a < 160, and the longitudinal cross-sectional shape of the first trench 4 is inverted trapezoidal. The shape and structure of the first trench 4 can refer to the description of the previous structural embodiments, which will not be repeated here. The etching process of the first trench 4 is a dry etching process, which includes but is not limited to inductively coupled plasma (ICP) etching, reactive ion etching (RIE), ion beam etching, plasma etching or laser cutting. The angle a between the sidewall of the etched first trench 4 and the plane of the piezoelectric layer 32 is an obtuse angle. When etching the first trench 4, the first electrode layer can also be patterned to form the first electrode 31. The patterning process of the first electrode layer can refer to the description above, which will not be repeated here.

[0101] After step S03 is performed, step S08 can also be performed to form a dielectric layer in the first trench 4. Specifically, the first trench 4 is filled with a dielectric material to form a dielectric layer. The dielectric layer can be formed in the first trench 4 by deposition, which can be chemical vapor deposition or physical vapor deposition. The structure, shape and material of the dielectric layer can refer to the description of the dielectric layer disposed in the first trench 4 and the first dielectric layer in the previous structural embodiments, which will not be repeated here.

[0102] In addition, before forming the first trench 4, it also includes forming an isolation layer 7 on the surface of the first electrode layer 31’. Specifically, before forming the first trench 4, the isolation layer 7 is formed to cover the first electrode layer 31’, so that when the first trench 4 is formed, the first trench 4 penetrates the isolation layer 7, the first electrode 31 and the piezoelectric layer 32. It should be noted that when the isolation layer 7 is formed before the first trench 4 is formed, the first electrode layer 31’ needs to be patterned to form the first electrode before the isolation layer 7 is formed. In other embodiments, after the dielectric layer in the first trench 4 is formed, the isolation layer 7 is formed to cover the first electrode layer 31’ and the dielectric layer formed in the first trench 4. The first electrode 31 and the support layer 2 are isolated by the isolation layer 7, so as to avoid etching the dielectric layer in the first trench 4 when etching the first cavity, prevent over-etching, and protect the surface of the first electrode 31 below from being damaged, thereby improving the performance and reliability of the device. The isolation layer 7 can be formed on the first electrode layer 31’ by physical vapor deposition such as magnetron sputtering, evaporation or chemical vapor deposition. The material of the isolation layer 7 includes silicon oxide or silicon nitride.

[0103] Reference Figure 6 After step S03 is performed, step S08 can also be performed to form a dielectric layer in the first trench 4. Specifically, the first trench 4 is filled with a dielectric material to form a dielectric layer. The dielectric layer can be formed in the first trench 4 by deposition, which can be chemical vapor deposition or physical vapor deposition. The structure, shape and material of the dielectric layer can refer to the description of the dielectric layer disposed in the first trench 4 and the first dielectric layer in the previous structural embodiments, which will not be repeated here.

[0104] The support layer 2 can be formed on the first electrode 31 by deposition or bonding. It should be noted that the support layer 2 can be combined with the first electrode 31 by bonding or deposition. The deposition can be chemical vapor deposition or physical vapor deposition. The bonding includes thermal compression bonding or dry film bonding. The first electrode 31 and the support layer 2 can also be bonded by a bonding layer, and the material of the bonding layer includes silicon oxide, silicon nitride, silicon oxynitride, silicon carbon nitride or ethyl silicate. In addition, the bonding layer can also use a light-cured material or a heat-cured material as an adhesive, such as a die attach film (DAF) or a dry film. In other embodiments, the bonding can also include covalent bonding, adhesive bonding or fusion bonding. The material of the support layer 2 can be the same as the material of the temporary substrate 9, or can be any suitable dielectric material, including but not limited to one of silicon oxide, silicon nitride, silicon oxynitride, silicon carbon nitride, etc. In other embodiments, the first cavity 21 is not limited to being arranged in the support layer 2, and the first cavity 21 can also be formed directly in the first substrate 1 without the support layer 2, and the piezoelectric layer structure 3 is arranged directly on the first substrate.

[0105] In the process of forming the support layer 2, step S08 of forming a dielectric layer 6 in the first trench 4 can also be performed. The dielectric layer 6 formed in the first trench 4 is a first dielectric layer 61. Specifically, a first dielectric material layer is formed to fill the first trench 4 and cover the first electrode 31; the first dielectric material layer is etched to form the first cavity 21, and the part of the first dielectric material layer surrounding the first cavity 21 forms the support layer 2, and the part of the first dielectric material layer formed in the first trench 4 forms the first dielectric layer 61. It should be noted that after the first dielectric material layer is formed, a chemical mechanical polishing (CMP) process is required to planarize the first dielectric material layer. In addition, the outer periphery of the first dielectric layer 61 is in contact with the side wall of the first trench 4, and the first surface thereof is flush with the first surface of the first electrode 31.

[0106] It should be noted that the first surface of the first dielectric layer 61 is the surface adjacent to the isolation layer 7, and the first surface of the first electrode 31 is the surface in contact with the isolation layer 7. When the isolation layer 7 is formed on the first electrode layer, the first cavity 21 can penetrate the support layer 2 or penetrate the support layer 2 and the isolation layer 7 when the first cavity 21 is formed. When the first cavity 21 penetrates the isolation layer 7, the first trench 4 and the first cavity 21 are in communication to avoid leakage of sound waves from the isolation layer 7, thereby better inhibiting the leakage of sound waves. In addition, when the alignment mark is formed, the first dielectric material layer also fills the alignment mark to improve the strength of the device structure.

[0107] In other embodiments, before or after forming the support layer 2, step S08 is performed to form a dielectric layer 6 in the first trench 4, the dielectric layer 6 being a first dielectric layer 61, specifically comprising: forming the first dielectric layer 61 to fill the first trench 4; forming the support layer 2 to cover the first electrode 31 and the first dielectric layer 61; etching the support layer 2 to form the first cavity 21 penetrating through the support layer 2, the first cavity 21 exposing part of the surface of the piezoelectric layer 32 and the first trench 4 or the first dielectric layer 61. It should be noted that after forming the support layer 2, the support layer 2 needs to be planarized. In addition, at least part of the outer periphery of the formed first dielectric layer 61 is in contact with the sidewall of the first trench 4; or the entire outer periphery of the formed first dielectric layer 61 is not in contact with the sidewall of the first trench 4. The first surface of the formed first dielectric layer 61 can be flush with or not flush with the first surface of the first electrode 31. When the entire outer periphery of the formed first dielectric layer 61 is in contact with the sidewall of the first trench 4, and the first surface of the formed first dielectric layer 61 is flush with the first surface of the first electrode 31, the support effect of the first dielectric layer 61 and the first electrode 31 in the region where the first trench 4 is located is the best, and the firmness of the device structure is the best.

[0108] Reference Figure 7 Step S05 is performed to bond the first substrate 1 to the support layer 2.

[0109] In the present embodiment, the first substrate 1 can be directly bonded to the support layer 2; or the first substrate 1 can be combined with the support layer through a bonding layer. The material of the bonding layer includes silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride or ethyl silicate. In addition, the bonding layer can also use an adhesive such as a light-cured material or a heat-cured material, for example, a die attach film (DAF) or a dry film.

[0110] Reference Figure 8, after the bonding process, step S06 is performed to remove the temporary substrate, and the bonded thin film bulk acoustic resonator is flipped over so that the second electrode layer 33' is patterned after the first electrode 31 is patterned, thereby ensuring the flatness of the piezoelectric layer 32 as a whole, and further ensuring that the piezoelectric layer 32 has good piezoelectric properties, and further ensuring that the first electrode 31 and the second electrode have a flat surface. When the temporary substrate and the second electrode layer 33' form an insulating layer, the temporary substrate can be peeled off by etching the insulating layer; when the temporary substrate and the second electrode layer 33' do not form an insulating layer, the temporary substrate can be removed by other methods, such as etching or mechanical grinding. It should be noted that the patterning of the second electrode layer 33' can be performed after the temporary substrate is removed, before or after the second trench is formed, or simultaneously with the step of forming the second trench. The patterning of the second electrode layer 33' can refer to the patterning process of the first electrode layer described above, and will not be described here. The second electrode 33, the piezoelectric layer 32, and the first electrode 31 form a piezoelectric layer structure.

[0111] In this embodiment, the second electrode 33 formed by etching overlaps the first electrode 31 in a direction perpendicular to the piezoelectric layer 32. In other embodiments, the first electrode 31, the second electrode 33, and the piezoelectric layer 32 outside the effective resonant region do not overlap each other in a direction perpendicular to the surface of the piezoelectric layer 32, thereby avoiding high-frequency coupling problems caused by potential floating, and facilitating improvement of the resonator Q value.

[0112] Reference Figure 9 Step S07 is performed to form a second trench 5 that penetrates the second electrode layer and the piezoelectric layer 32. The area enclosed by the first trench 4 and the second trench 5 is the effective resonant region of the resonator.

[0113] The sidewall of the first trench 5 can be inclined or vertical. In this embodiment, the angle β between the sidewall of the second trench 5 and the plane of the piezoelectric layer 32 is 90 < β < 160, and the longitudinal cross-sectional shape of the second trench 5 is inverted trapezoidal. The shape and structure of the second trench can refer to the structure described in the foregoing embodiments, and will not be described here. The second trench 5 can be formed by etching, and the process of etching the second trench 5 can refer to the process of etching the first trench 4, and will not be described here.

[0114] In some embodiments, the first electrode 31 and the second electrode 33 are patterned only when the first trench and the second trench 5 are formed, and the effective resonant region is defined, thereby saving the process.

[0115] Reference Figure 10 Step S08 is performed to form a dielectric layer 6 in the second trench 5.

[0116] In the embodiment, the dielectric material is filled in the second trench 5 to form the dielectric layer 6, and the dielectric layer 6 formed in the second trench 5 is the second dielectric layer 62. The second dielectric layer 62 can be formed in the second trench 5 by deposition.

[0117] After the second trench 5 is formed, the dielectric layer 6 in the second trench 5 is formed, which specifically includes: forming a second dielectric material layer to fill the second trench 5 and cover at least part of the second electrode 33; removing the second dielectric material layer outside the periphery of the second trench 5, and the second dielectric material layer in the second trench 5 forms the second dielectric layer 62. The method for removing the second dielectric material layer outside the periphery of the second trench 5 includes: planarizing the second dielectric material layer by grinding; etching the second dielectric material layer to expose the second electrode 33. In addition, the grinding method can use chemical mechanical polishing (CMP). The structure, shape and material of the second dielectric layer 62 can refer to the structure embodiments described above, and will not be described here.

[0118] The method for forming the dielectric layer 62 in the second trench 5 further includes: before forming the second trench 5, forming an etching stop layer to cover the second electrode layer 33; forming the second trench 5 to penetrate the etching stop layer, the second electrode layer and the piezoelectric layer 32; forming a second dielectric material layer to fill the second trench 5 and cover the etching stop layer; removing the second dielectric material layer above the etching stop layer; removing the etching stop layer by etching or grinding, so that the second dielectric material layer in the second trench 5 forms the dielectric layer 6.

[0119] In the embodiment, the periphery of the second dielectric layer 62 is in contact with the sidewall of the second trench 5, and the first surface of the second dielectric layer 62 is flush with the first surface of the second electrode 33, so as to ensure the supporting effect of the second dielectric layer 62 and the second electrode 33 in the area where the second trench 5 is located, and ensure that the firmness of the device structure is good. In other embodiments, at least part of the periphery of the second dielectric layer 62 has a gap with the sidewall of the second trench 5; and / or the first surface of the second dielectric layer 62 is not flush with the first surface of the second electrode 33. It should be noted that the first surface of the second electrode 33 is the surface opposite to the contact surface with the piezoelectric layer 32, and the first surface of the second dielectric layer 62 is the surface close to the first surface of the second electrode 33. The second dielectric layer 62 can be formed in the second trench 4 by deposition, and the specific method can refer to the deposition method of the first dielectric layer 61 described above, which will not be described here.

[0120] Reference Figure 11 After the second trench 5 is formed, the method further includes: forming a vent hole 8 in the piezoelectric layer structure, and the vent hole 8 penetrates the piezoelectric layer structure to communicate with the first cavity 21, so as to keep the pressure inside and outside the first cavity 21 balanced. When the isolation layer 7 is further formed between the first electrode 31 and the support layer 2, the vent hole 8 also penetrates the isolation layer 7.

[0121] In addition, in order to avoid the pollution of each layer exposed in the upper space by the external environment, a top cover is bonded above the piezoelectric laminated structure, and the top cover has a second cavity located above the first cavity 21.

[0122] In summary, the manufacturing method of the thin film bulk acoustic resonator provided by the application strengthens the firmness of the device structure by forming the dielectric layer in the first groove and / or the second groove to support the first electrode and / or the second electrode at the groove, thereby avoiding damage to the resonator structure; the first groove and the second groove are formed by a double-sided process, the piezoelectric layer can be formed flat, the integrity and flatness of the piezoelectric layer are ensured, the influence on the piezoelectric layer is reduced, thereby improving the performance of the resonator, and the method is compatible with the main process of the resonator, the process is simple, and the effective resonant area is effectively protected; the first groove and the second groove formed around the effective resonant area to suppress the energy leakage of the acoustic wave.

[0123] Further, by forming the dielectric layer and then etching the dielectric layer to simultaneously form the first dielectric layer, the support layer and the first cavity, the process steps are saved and the production efficiency is improved.

[0124] Further, by arranging the isolation layer, the first electrode and the first dielectric material layer are isolated, so that the first dielectric layer located in the first groove is not etched when the first cavity is etched, thereby avoiding damaging the flatness of the surface of the first dielectric layer and the surface of the first electrode layer, and further improving the firmness of the device structure.

[0125] Further, by arranging the etching stop layer, the second electrode and the second dielectric material layer can be isolated, so that the flatness of the surface of the second dielectric layer and the surface of the second electrode layer is not damaged when the second dielectric layer is formed by removing the excess second dielectric material layer, thereby further improving the firmness of the device structure.

[0126] It should be noted that each embodiment in the present specification is described in a related manner, and the same and similar parts between each embodiment can be referred to each other, and each embodiment mainly describes the difference from other embodiments. In particular, for the structural embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the related parts can be referred to the part of the method embodiment.

[0127] The above description is only a description of the preferred embodiments of the application, and does not limit the scope of the application in any way, and any modification or modification of the application by a person skilled in the art according to the above disclosure is within the protection scope of the claims.

Claims

1. A thin-film bulk acoustic resonator, characterized in that, include: A first substrate and a support layer disposed on the first substrate, wherein the support layer has a first cavity; A piezoelectric stacked structure covers the first cavity, the piezoelectric stacked structure comprising a first electrode, a piezoelectric layer and a second electrode stacked sequentially. A first trench is disposed on the piezoelectric stack structure and penetrates the first electrode and the piezoelectric layer, and the first trench is connected to the first cavity; The second trench is disposed on the piezoelectric stack structure and penetrates the second electrode and the piezoelectric layer; The area enclosed by the first trench and the second trench is the effective resonant region of the resonator; A dielectric layer is disposed within the first trench and / or the second trench; The acoustic impedance of the dielectric layer material is different from that of the piezoelectric layer material; The angle between the sidewall of the first trench and the plane containing the second electrode is greater than 90 degrees and less than 160 degrees; the angle between the sidewall of the second trench and the plane containing the first electrode is greater than 90 degrees and less than 160 degrees.

2. The thin-film bulk acoustic resonator according to claim 1, characterized in that, The outer periphery of the medium layer disposed in the first trench is in contact with the sidewall of the first trench; And / or, The outer periphery of the medium layer disposed in the second trench is in contact with the sidewall of the second trench.

3. The thin-film bulk acoustic resonator according to claim 1, characterized in that, The first surface of the dielectric layer disposed in the first trench is flush with the first surface of the first electrode; And / or, The first surface of the dielectric layer disposed in the second trench is flush with the first surface of the second electrode.

4. The thin-film bulk acoustic resonator according to claim 1, characterized in that, The dielectric layer is a continuous whole, and the projection of the dielectric layer on the surface of the piezoelectric layer is annular, semi-annular, or polygonal. Alternatively, the dielectric layer may comprise a plurality of discontinuously arranged sub-dielectric layers, the projection of which onto the surface of the piezoelectric layer is a ring, semi-ring, or polygon with gaps.

5. The thin-film bulk acoustic resonator according to claim 1, characterized in that, The material of the dielectric layer includes one or a combination of silicon dioxide, silicon nitride, and aluminum oxide.

6. The thin-film bulk acoustic resonator according to claim 1, characterized in that, It also includes an isolation layer disposed between the first electrode and the support layer.

7. The thin-film bulk acoustic resonator according to claim 6, characterized in that, The insulating layer material includes silicon oxide or silicon nitride.

8. The thin-film bulk acoustic resonator according to claim 1, characterized in that, It also includes a vent hole, which is disposed on the piezoelectric stack structure and penetrates the piezoelectric stack structure, and the vent hole is connected to the first cavity.

9. The thin-film bulk acoustic resonator according to claim 1, characterized in that, The first and second electrodes, outside the effective resonant region, are in a region where they do not overlap in the direction perpendicular to the piezoelectric layer.

10. A method for manufacturing a thin-film bulk acoustic resonator, characterized in that, include: Provide a temporary substrate; A second electrode layer, a piezoelectric layer, and a first electrode layer are sequentially formed on the temporary substrate; A first trench is formed, penetrating the first electrode layer and the piezoelectric layer; A support layer is formed on the first electrode layer, and a first cavity is formed on the support layer to expose a portion of the first electrode layer; A first substrate is bonded to the support layer, and the first substrate covers the first cavity; Remove the temporary substrate; A second trench is formed, penetrating the second electrode layer and the piezoelectric layer. The area enclosed by the first trench and the second trench is the effective resonant region of the resonator. Before bonding the first substrate, a dielectric layer is formed within the first trench; And / or, after forming the second trench, a dielectric layer is formed within the second trench.

11. The method for manufacturing a thin-film bulk acoustic resonator according to claim 10, characterized in that, When forming the support layer, a dielectric layer is formed within the first trench. The dielectric layer is a first dielectric layer, specifically comprising: A first dielectric material layer is formed to fill the first trench and cover the first electrode layer; The first dielectric material layer is etched to form the first cavity. The portion of the first dielectric material layer surrounding the first cavity forms the support layer, and the portion of the first dielectric material layer formed within the first trench forms the first dielectric layer.

12. The method for manufacturing a thin-film bulk acoustic resonator according to claim 10, characterized in that, Before or after the formation of the support layer, a dielectric layer is formed within the first trench, the dielectric layer being a first dielectric layer, specifically comprising: A first dielectric layer is formed to fill the first trench; A support layer is formed to cover the first electrode layer and the first dielectric layer; The support layer is etched to form a first cavity penetrating the support layer.

13. The method for manufacturing a thin-film bulk acoustic resonator according to claim 10, characterized in that, Also includes: Before forming the first trench, an isolation layer is formed to cover the first electrode layer, and the isolation layer is penetrated during the formation of the first trench. Alternatively, after forming the first trench, an isolation layer is formed, which covers the first electrode layer and the first trench or the dielectric layer located within the first trench.

14. The method for manufacturing a thin-film bulk acoustic resonator according to claim 13, characterized in that, When the first cavity is formed, the first cavity penetrates the support layer and the isolation layer.

15. The method for manufacturing a thin-film bulk acoustic resonator according to claim 10, characterized in that, After the second trench is formed, a dielectric layer is formed within the second trench. The dielectric layer is a second dielectric layer, specifically comprising: A second dielectric material layer is formed to fill the second trench and cover at least a portion of the second electrode layer; The second dielectric material layer on the outer periphery of the second trench is removed, and the second dielectric material layer inside the second trench is formed into the second dielectric layer.

16. The method for manufacturing a thin-film bulk acoustic resonator according to claim 15, characterized in that, The method for removing the second dielectric material layer around the outer periphery of the second trench includes: The second dielectric material layer is smoothed by grinding. The second dielectric material layer is etched to expose the second electrode layer.

17. The method for manufacturing a thin-film bulk acoustic resonator according to claim 10, characterized in that, The method for forming a dielectric layer located within the second trench further includes: Before forming the second trench, an etch stop layer is formed to cover the second electrode layer; The second trench is formed, penetrating the etch stop layer, the second electrode layer, and the piezoelectric layer; A second dielectric material layer is formed to fill the second trench and cover the etching stop layer; Remove the second dielectric material layer located above the etching stop layer; The etching stop layer is removed by etching, and the second dielectric material layer located in the second trench forms a dielectric layer.

18. The method for manufacturing a thin-film bulk acoustic resonator according to claim 10, characterized in that, After forming a second electrode layer, a piezoelectric layer, and a first electrode layer sequentially on the temporary substrate, the first electrode layer is patterned to form a first electrode, and after removing the temporary substrate, the second electrode layer is patterned to form a second electrode, wherein the surfaces of the first electrode, the piezoelectric layer, and the second electrode are flat.

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