CN112117985A

CN112117985A - Resonator and forming method thereof

Info

Publication number: CN112117985A
Application number: CN202010324195.0A
Authority: CN
Inventors: 黄河; 罗海龙; 李伟
Original assignee: China Core Integrated Circuit Ningbo Co Ltd
Current assignee: China Core Integrated Circuit Ningbo Co Ltd
Priority date: 2020-04-22
Filing date: 2020-04-22
Publication date: 2020-12-22
Anticipated expiration: 2040-04-22
Also published as: CN112117985B; WO2021212882A1

Abstract

A resonator and a forming method thereof are provided, the forming method of the resonator comprises the following steps: a first electrode; a piezoelectric layer on the first electrode; a second electrode on the piezoelectric layer; one or two of the first electrode and the second electrode are composite laminated layers, each composite laminated layer comprises a first metal layer opposite to the piezoelectric layer and a second metal layer located on one side, opposite to the piezoelectric layer, of the first metal layer, the surface roughness of the first metal layer is smaller than that of the second metal layer, and the resistivity of the first metal layer is larger than that of the second metal layer. According to the embodiment of the invention, the total resistance of the first electrode and the second electrode is smaller; in addition, the piezoelectric layer is formed on the first metal layer with smaller roughness, the consistency of the crystal direction growth direction of the piezoelectric layer is better, and in summary, in the process that signals pass through the resonator, because the total resistance of the first electrode and the second electrode is smaller and the forming quality of the piezoelectric layer is better, the insertion loss of the resonator can be reduced, and the performance of the resonator is improved.

Description

Resonator and forming method thereof

Technical Field

The invention relates to the field of semiconductors, in particular to a resonator and a forming method thereof.

Background

Since the development of analog rf communication technology in the early 90 th century, rf front-end modules have gradually become the core components of communication devices. In all rf front-end modules, the filter has become the most fierce component to grow and have the greatest development prospect. With the rapid development of wireless communication technology, 5G communication protocols are becoming mature, and the market also puts forward more strict standards on various aspects of the performance of radio frequency filters. The performance of the filter is determined by the resonator elements that make up the filter. Among the existing filters, the Film Bulk Acoustic Resonator (FBAR) is one of the most suitable filters for 5G applications due to its small size, low insertion loss, large out-of-band rejection, high quality factor, high operating frequency, large power capacity, and good anti-electrostatic shock capability.

Generally, a film bulk acoustic resonator includes two film electrodes, and a piezoelectric film layer is disposed between the two film electrodes, and the working principle of the film bulk acoustic resonator is to utilize the piezoelectric film layer to generate vibration under an alternating electric field, the vibration excites a bulk acoustic wave propagating along the thickness direction of the piezoelectric film layer, the acoustic wave is transmitted to an interface between an upper electrode and a lower electrode and an air interface to be reflected back, and then reflected back and forth inside the film to form oscillation. When the sound wave is transmitted in the piezoelectric film layer and is just odd times of half wavelength, standing wave oscillation is formed.

However, the insertion loss of the currently manufactured cavity type film bulk acoustic resonator is large, and thus the requirement of a high-performance radio frequency system cannot be met.

Disclosure of Invention

The invention provides a resonator and a forming method thereof, which can improve the performance of the resonator.

In order to solve the above problems, the present invention provides a method for forming a resonator, including: a first electrode; a piezoelectric layer on the first electrode; a second electrode on the piezoelectric layer; one or two of the first electrode and the second electrode are composite laminated layers, each composite laminated layer comprises a first metal layer opposite to the piezoelectric layer and a second metal layer located on one side, opposite to the piezoelectric layer, of the first metal layer, the surface roughness of the first metal layer is smaller than that of the second metal layer, and the resistivity of the first metal layer is larger than that of the second metal layer.

Correspondingly, the invention also provides a resonator, comprising: forming a first electrode; forming a piezoelectric layer on the first electrode; forming a second electrode on the piezoelectric layer; one or two of the first electrode and the second electrode are composite laminated layers, each composite laminated layer comprises a first metal layer opposite to the piezoelectric layer and a second metal layer located on one side, opposite to the piezoelectric layer, of the first metal layer, the surface roughness of the first metal layer is smaller than that of the second metal layer, and the resistivity of the first metal layer is larger than that of the second metal layer.

Compared with the prior art, the technical scheme of the invention has the following advantages:

in the method for forming a resonator provided in the embodiment of the present invention, one or both of the first electrode and the second electrode is a composite laminate, the composite laminate includes a first metal layer opposite to the piezoelectric layer and a second metal layer located on a side of the first metal layer opposite to the piezoelectric layer, a surface roughness of the first metal layer is smaller than a surface roughness of the second metal layer, and a resistivity of a material corresponding to the first metal layer is larger than a resistivity of a material corresponding to the second metal layer.

When the first electrode and the second electrode are both composite laminates, because the resistivity of the material corresponding to the second metal layer is smaller than the resistivity of the material corresponding to the first metal layer, the total resistance of the first electrode and the second electrode is smaller than that of the case where the first electrode and the second electrode only include the first metal layer; in addition, in the process of forming the piezoelectric layer on the first electrode, the piezoelectric layer is formed on the first metal layer with smaller surface roughness, so that the uniformity of the crystal direction growth direction of the piezoelectric layer is better, and the forming quality of the piezoelectric layer is better; in summary, in the process of passing a signal through the resonator, because the total resistance of the first electrode and the second electrode is small and the quality of the piezoelectric layer is good, the insertion loss of the resonator can be reduced, which is beneficial to improving the performance of the resonator.

When the first electrode or the second electrode is a composite lamination, because the resistivity of the material corresponding to the second metal layer is smaller than that of the material corresponding to the first metal layer, compared with the case that the first electrode and the second electrode only comprise the first metal layer, the total resistance of the first electrode and the second electrode is smaller, the insertion loss of the resonator can be reduced in the process that signals pass through the resonator, and the performance of the resonator is improved.

Drawings

Fig. 1 is a schematic diagram of a resonator structure.

Fig. 2 to 16 are schematic structural diagrams corresponding to steps in an embodiment of a method for forming a resonator according to the present invention.

Detailed Description

As known in the background art, Film Bulk Acoustic Resonators (FBAR) are widely used. The reason for the poor performance of the device is analyzed in combination with a method for forming a semiconductor structure.

The resonator includes: a first electrode 1; a piezoelectric layer 2 on the first electrode 1; a second electrode 3 on the piezoelectric layer 2; a first support layer 7 on the second electrode 3, the first support layer 7 having a first opening therein; the first substrate 9 is positioned on the first supporting layer 7, and a first cavity 8 is defined by the first substrate 9, the first supporting layer 7 and the second electrode 3; and the signal input electrode 4 and the signal output electrode 5 penetrate through the first electrode 1 and the piezoelectric layer 2 from the side of the first electrode 1, which is opposite to the piezoelectric layer 2, and are electrically connected with the second electrode 3, and the signal input electrode 4 and the signal output electrode 5 are positioned outside the first cavity 8.

Generally, the first electrode 1 and the second electrode 3 are made of tungsten, which has a very high melting point, belongs to the metal, and has a high electron emission capability, and therefore, the tungsten is used as an electrode material at first, but tungsten has a disadvantage of a relatively high resistivity, so that the total resistance of the first electrode 1 and the second electrode 3 is relatively large, and when the resonator operates, a signal is transmitted from the signal input electrode 4 and transmitted from the signal output electrode 5, which causes a relatively large insertion loss.

When the first electrode and the second electrode are both composite laminates, because the resistivity of the material corresponding to the second metal layer is smaller than the resistivity of the material corresponding to the first metal layer, the total resistance of the first electrode and the second electrode is smaller than that of the case where the first electrode and the second electrode only include the first metal layer; in addition, in the process of forming the piezoelectric layer on the first electrode, the piezoelectric layer is formed on the first metal layer with smaller surface roughness, so that the uniformity of the crystal direction growth direction of the piezoelectric layer is better, and the forming quality of the piezoelectric layer is better; in summary, in the process of passing a signal through the resonator, because the total resistance of the first electrode and the second electrode is small and the quality of the piezoelectric layer is good, the insertion loss of the resonator can be reduced, which is beneficial to improving the performance of the resonator. When the first electrode or the second electrode is a composite lamination, because the resistivity of the material corresponding to the second metal layer is smaller than that of the material corresponding to the first metal layer, compared with the case that the first electrode and the second electrode only comprise the first metal layer, the total resistance of the first electrode and the second electrode is smaller, the insertion loss of the resonator can be reduced in the process that signals pass through the resonator, and the performance of the resonator is improved.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.

Referring to fig. 2 and 3, a first electrode 104 (shown in fig. 3) is formed.

Subsequently, a piezoelectric layer is formed on the first electrode 104, a second electrode is formed on the piezoelectric layer, the piezoelectric layer is made of a piezoelectric material, the piezoelectric material has a piezoelectric effect, that is, the piezoelectric material is a crystal material which generates voltage between two end faces when the piezoelectric material is under pressure, and the piezoelectric effect of the piezoelectric material can be used for realizing mutual conversion between mechanical vibration (sound wave) and alternating current, so that conversion between sound energy and electric energy is realized. The first electrode 104 and the second electrode are used to convert mechanical vibrations generated by the piezoelectric layer into electrical properties when the resonator is in operation.

In this embodiment, the material of the first electrode 104 is a composite laminate, the composite laminate includes a first metal layer 103 opposite to the piezoelectric layer and a second metal layer 102 located on a side of the first metal layer 103 opposite to the piezoelectric layer, a surface roughness of the first metal layer 103 is smaller than a surface roughness of the second metal layer 102, and a resistivity of the first metal layer 103 is greater than a resistivity of the second metal layer 102.

Specifically, the step of forming the first electrode 104 includes: as shown in fig. 2, a second metal layer 102 is formed.

In this embodiment, in the step of forming the second metal layer 102, the resistivity of the second metal layer 102 is less than 5.2 Ω/m. The resistivity of the second metal layer 102 is small, and the first metal layer is formed on the second metal layer 102 subsequently, which is beneficial to making the resistance of the first electrode formed by the second metal layer 102 and the first metal layer small, so that the resistance of the first electrode meets the working requirement.

Specifically, the material of the second metal layer 102 includes one or more of Al, Au, Ni, and Ag. In this embodiment, the material of the second metal layer 102 includes Al.

In this embodiment, the second metal layer 102 is formed by a Physical Vapor Deposition (PVD) process. The physical vapor deposition process has the advantages of low deposition temperature (usually below 550 ℃), high deposition speed, controllable components and structure of a deposition layer, simple operation, high efficiency and low cost, and the physical vapor deposition process has high compatibility with the existing machine and process flow. In other embodiments, the second metal Layer may be formed by an Atomic Layer Deposition (ALD) process or a Chemical Vapor Deposition (CVD) process.

It should be noted that second metal layer 102 is not too thick nor too thin. If the second metal layer 102 is too thick, too much process time is required to form the second metal layer 102, which is not easy to improve the forming efficiency of the second metal layer 102, and if the second metal layer 102 is too thick, the corresponding first electrode is too thick, which is easy to cause the volume of the resonator to be too large, and is not beneficial to improving the quality factor of the resonator. The resistivity of the first metal layer formed on the second metal layer 102 subsequently is greater than the resistivity of the second metal layer 102, and if the second metal layer 102 is too thin, the resistance of the first electrode formed by the second metal layer 102 and the first metal layer formed subsequently is likely to be greater, and the resistance of the first electrode is unlikely to meet the working requirement. In this embodiment, the thickness of the second metal layer 102 is

To

The method for forming a resonator includes: before forming the second metal layer 102, a temporary substrate 100 is provided, and a first buffer layer 101 is formed on the temporary substrate 100.

The temporary substrate 100 provides a process platform for subsequent process steps.

In this embodiment, the temporary substrate 100 may be any suitable semiconductor substrate, such as a bulk silicon substrate, which may also be at least one of the following materials: SiGe, Sic, SiGeC, TnAs, GaAs, Inp or other group iii and group v compound semiconductors, and also includes multilayer structures of these semiconductors, or the like, or silicon-on-insulator (SOI), silicon-on-insulator (SSOI), silicon-on-insulator-silicon-germanium (S-SiGeOI), silicon-on-insulator-silicon-germanium (SiGe01), and germanium-on-insulator (GeOI), or may also be Double Side Polished silicon Wafers (DSP), or may also be ceramic substrates such as alumina, quartz, glass substrates, or the like.

The first buffer layer 101 is used to improve the interface quality of the surface of the temporary substrate 100, and serves as a buffer between the first electrode and the temporary substrate 100, to improve the growth uniformity of the first electrode, and to improve the adhesion between the temporary substrate 100 and the first electrode. The method for forming the subsequent resonator further comprises the following steps: the temporary substrate 100 is removed, and the first buffer layer 101 is used as a stop layer in the step of removing the temporary substrate 100, so that the difficulty of removing the temporary substrate 100 is reduced, and the influence of a subsequent process for removing the temporary substrate 100 on the first electrode is favorably prevented.

The material of the first buffer layer 101 may be one or more of silicon oxide, silicon nitride, and silicon oxynitride. In this embodiment, the first buffer layer 101 is made of silicon oxide.

In this embodiment, the first buffer layer 101 is formed by a deposition process. Specifically, the deposition process may be a chemical vapor deposition process or an atomic layer deposition process, or the like.

As shown in fig. 3, a first metal layer 103 is formed on the second metal layer 102. The surface roughness of the first metal layer 103 is less than the surface roughness of the second metal layer 102.

The surface roughness of first metal level 103 is less, can improve better interface state for follow-up formation piezoelectric layer, can make the piezoelectric layer grow out the better crystal orientation of uniformity, is favorable to improving the formation quality of follow-up piezoelectric layer that forms on first metal level 103, and at the syntonizer during operation, the signal passes through the syntonizer, is difficult for causing the phenomenon that the insertion loss is bigger partially.

It should be noted that the surface roughness of the first metal layer 103 is not excessively large. If the surface roughness of the first metal layer 103 is too large, it is not easy to provide a better interface state for the subsequent formation of the piezoelectric layer, resulting in poor formation quality of the piezoelectric layer, and when the resonator works, a signal passes through the resonator, which easily causes a phenomenon of large insertion loss. In this embodiment, the surface roughness of the first metal layer 103 is less than

In this embodiment, the material of the first metal layer 103 includes one or both of W and Mo.

In this embodiment, the first metal layer 103 is formed by a physical vapor deposition process. The physical vapor deposition process has the advantages of low deposition temperature (usually below 550 ℃), high deposition speed, controllable components and structure of a deposition layer, simple operation, high efficiency and low cost, and the physical vapor deposition process has high compatibility with the existing machine and process flow. The physical vapor deposition process also has the advantages of simple process, little pollution, low process cost, compact film formation, strong bonding force with other film structures and the like. In other embodiments, the first metal layer may be formed by an atomic layer deposition process or a chemical vapor deposition process.

It should be noted that the first metal layer 103 is not too thick nor too thin. If the first metal layer 103 is too thick, too much process time is required to form the first metal layer 103, which is not easy to improve the forming efficiency of the first metal layer 103, and if the first metal layer 103 is too thick, the corresponding first electrode 104 is too thick, which is easy to cause the volume of the resonator to be too large, and is not favorable for improving the quality factor of the resonator. If the first metal layer 103 is too thin, it is not easy to provide a better interface state for the subsequent formation of the piezoelectric layer, resulting in poor quality of the piezoelectric layer, and when the resonator works, a signal passes through the resonator, which easily causes a phenomenon of large insertion loss. In this embodiment, the thickness of the first metal layer 103 is

To

Referring to fig. 4, a piezoelectric layer 105 is formed on the first electrode 104.

In the process of forming the piezoelectric layer 105, the piezoelectric layer 105 is formed on the first metal layer 103 with small surface roughness, so that the consistency of the crystal growth direction of the piezoelectric layer 105 is better, the forming quality of the piezoelectric layer 105 is better, and in the process of passing signals through the resonator, because the forming quality of the piezoelectric layer 105 is better, the insertion loss of the resonator can be reduced, and the performance of the resonator is improved.

The piezoelectric layer 105 is made of a piezoelectric material having a piezoelectric effect, that is, the piezoelectric material is a crystal material that generates a voltage between two end surfaces when the piezoelectric material is subjected to a pressure, and the piezoelectric effect of the piezoelectric material can be utilized to realize mutual conversion between mechanical vibration (sound waves) and alternating current, thereby realizing conversion between sound energy and electric energy.

The material of the piezoelectric layer 105 may be a piezoelectric material having a wurtzite crystal structure, such as ZnO, AlN, GaN, aluminum zirconate titanate, or lead titanate. In this embodiment, the material of the piezoelectric layer 105 is AlN.

In this embodiment, the piezoelectric layer 105 may be formed by a chemical vapor deposition process, a physical vapor deposition process, an atomic layer deposition process, or other deposition processes.

Referring to fig. 5, a second electrode 106 is formed on the piezoelectric layer 105. The second electrode 106 and the first electrode 104 are used to convert the mechanical vibration generated by the piezoelectric layer 105 into an electrical signal.

In this embodiment, the material of the second electrode 106 is a composite laminate, the composite laminate includes a first metal layer 103 opposite to the piezoelectric layer 105 and a second metal layer 102 located on a side of the first metal layer 103 opposite to the piezoelectric layer 105, a surface roughness of the first metal layer 103 is smaller than a surface roughness of the second metal layer 102, and a resistivity of the first metal layer 103 is greater than a resistivity of the second metal layer 102.

When the first electrode 104 and the second electrode 106 are both composite laminates, since the resistivity of the material corresponding to the second metal layer 102 is smaller than the resistivity of the material corresponding to the first metal layer 103, the total resistance of the first electrode 104 and the second electrode 106 is smaller than that in the case where the first electrode and the second electrode include only the first metal layer; in addition, in the process of forming the piezoelectric layer 105 on the first electrode 104, the piezoelectric layer 105 is formed on the first metal layer 103 with small surface roughness, so that the uniformity of the crystal growth direction of the piezoelectric layer 105 is good, and the forming quality of the piezoelectric layer 105 is good; in summary, in the process of passing a signal through the resonator, because the total resistance of the first electrode 104 and the second electrode 106 is small and the quality of the piezoelectric layer 105 is good, the insertion loss of the resonator can be reduced, which is beneficial to improving the performance of the resonator.

Specifically, the step of forming the second electrode 106 includes: a first metal layer 103 is formed on the piezoelectric layer 105.

The surface roughness of the first metal layer 103 is smaller than the surface roughness of the second metal layer 102 subsequently formed on the first metal layer 103.

The surface roughness of the first metal layer 103 is small, so that a better interface state can be improved for the subsequent formation of the second metal layer 102, the second metal layer 102 can grow to have a crystal orientation with better consistency, the formation quality of the subsequent second metal layer 102 formed on the first metal layer 103 is improved, and when the resonator works, a signal passes through the resonator, so that the phenomenon of large insertion loss is difficult to cause.

It should be noted that the surface roughness of the first metal layer 103 is not excessively large. If the surface roughness of the first metal layer 103 is too large, it is not easy to provide a better interface state for the subsequent formation of the second metal layer 102, resulting in a poor formation quality of the second metal layer 102, and when the resonator works, a signal passes through the resonator, which is easy to cause a phenomenon of large insertion loss. In this embodiment, the surface roughness of the first metal layer 103 is less than

In this embodiment, the first metal layer 103 is formed by a physical vapor deposition process. The physical vapor deposition process has the advantages of low deposition temperature (usually below 550 ℃), high deposition speed, controllable components and structure of a deposition layer, simple operation, high efficiency and low cost, and the physical vapor deposition process has high compatibility with the existing machine and process flow. In other embodiments, the first metal layer may be formed by an atomic layer deposition process or a chemical vapor deposition process.

It should be noted that the first metal layer 103 is not too thick nor too thin. If the first metal layer 103 is too thick, too much process time is required to form the first metal layer 103, which is not easy to improve the forming efficiency of the first metal layer 103, and if the first metal layer 103 is too thick, the corresponding first electrode is too thick, which is easy to cause the volume of the resonator to be too large, and is not beneficial to improving the resonatorQuality factor. If the first metal layer 103 is too thin, it is not easy to provide a better interface state for the subsequent formation of the second metal layer 102, resulting in a poor formation quality of the second metal layer 102, and when the resonator works, a signal passes through the resonator, which is easy to cause a phenomenon of large insertion loss. In this embodiment, the thickness of the first metal layer 103 is

To

With continued reference to fig. 5, a second metal layer 102 is formed on first metal layer 103.

In this embodiment, in the step of forming the second metal layer 102, the resistivity of the second metal layer 102 is less than 5.2 Ω/m. The resistivity of the second metal layer 102 is too small, and the first metal layer formed on the second metal layer 102 subsequently is beneficial to the small resistance of the first electrode formed by the second metal layer 102 and the first metal layer formed subsequently, so that the resistance of the first electrode meets the working requirement.

In this embodiment, the second metal layer 102 is formed by a physical vapor deposition process. The physical vapor deposition process has the advantages of low deposition temperature (usually below 550 ℃), high deposition speed, controllable composition and structure of a deposited layer, simple operation, high efficiency and low cost. In other embodiments, the second metal layer may be formed by an atomic layer deposition process or a chemical vapor deposition process.

It should be noted that second metal layer 102 is not too thick nor too thin. If the second metal layer 102 is too thick, too much process time is required to form the second metal layer 102, which is not easy to improve the forming efficiency of the second metal layer 102, and if the second metal layer 102 is too thick, the corresponding first electrode is too thick, which is easy to cause the volume of the resonator to be too large, and is not beneficial to improving the quality factor of the resonator. The resistivity of the second metal layer 102 is less than that of the first metal layerThe resistivity of the second electrode 103 is too low, which easily causes the resistance of the second electrode 106 formed by the second metal layer 102 and the first metal layer 103 to be large, and the resistance of the second electrode 106 is not easy to meet the working requirement. In this embodiment, the thickness of the second metal layer 102 is

To

It should be further noted that the surface roughness of the first metal layer 103 is small, which is beneficial to improving the formation quality of the second metal layer 102, so that the total resistance of the second electrode 106 is small, the insertion loss of the resonator can be reduced in the process of passing signals through the resonator, and the performance of the resonator can be improved.

Referring to fig. 6 and 7, the method of forming the resonator further includes: forming a first supporting material layer on the second electrode 106; the first supporting material layer is patterned to form a first opening 110 penetrating the first supporting material layer and exposing the second electrode 106, and the remaining first supporting material layer is used as a first supporting layer 111.

The first support layer 111 provides for subsequent bonding of the first substrate.

The first support material layer provides for the subsequent formation of a first support layer.

Specifically, the step of forming the first support material layer includes: forming a second buffer material layer 107 on the second electrode 106; forming an etch stop material layer 108 on the second buffer material layer 107; a support material film 109 is formed on the etch stop material layer 108.

The second buffer material layer 107 is used to reduce the stress between the etching stop material layer 108 and the second electrode 106, and prevent the peeling phenomenon caused by the overlarge stress between the etching stop material layer 108 and the second electrode 106.

In this embodiment, the material of the second buffer material layer 107 includes tetraethyl orthosilicate (TEOS). In other embodiments, the material of the second buffer material layer 107 includes: silicon oxide.

The etching stop material layer 108 can be used to increase the structural stability of the finally manufactured film bulk acoustic resonator, and on the other hand, the etched rate of the etching stop material layer 108 is smaller than that of the support material film 109, so that the etching stop material layer 108 can be temporarily stopped on the etching stop material layer 108 during the process of forming the first opening 110, over-etching is prevented, and the surface of the second electrode 106 located below the etching stop material layer is protected from being damaged, thereby improving the performance and reliability of the device.

In the present embodiment, the material of the etch stop material layer 108 includes, but is not limited to, silicon nitride and silicon oxynitride.

In this embodiment, the material of the support material film 109 includes: one or more of tetraethyl orthosilicate (TEOS), silicon oxide, silicon nitride, aluminum oxide and aluminum nitride.

In this embodiment, the first support material layer is etched by a dry etching process to form a first support layer. The dry etching process has anisotropic etching characteristics and better etching profile controllability, and is favorable for enabling the appearance of the first support layer to meet the process requirements; in the process of etching the first support material layer by adopting the dry etching process, each film layer can be etched in the same etching equipment by replacing etching gas, so that the process steps are simplified.

Specifically, the support material layer 109 is etched to form a support layer 113; the etch stop material layer 108 is etched to form an etch stop layer 114, and the second buffer material layer 107 is etched to form a second buffer layer 115.

In this embodiment, the bottom surface of the first opening 110 may be rectangular or polygonal other than rectangular, such as pentagonal, hexagonal, octagonal, etc., and may also be circular or elliptical. In other embodiments, the longitudinal cross-sectional shape of the first opening may also be a spherical cap with a wide top and a narrow bottom, i.e. the longitudinal cross-section of the first opening is U-shaped.

The method of forming the resonator further includes: after the first opening 110 is formed, the second electrode 106 exposed by the first opening 110 is etched, and a Bottom Air Trench (BAT) 125 exposing the piezoelectric layer 105 is formed.

The step of forming the bottom air slot 125 includes: forming a first blocking layer (not shown) filling the first opening 110, the first blocking layer including an organic material layer, an anti-reflective coating on the organic material layer, and a photoresist layer on the anti-reflective coating; the second electrode 106 is etched using the first mask layer as a mask to form a bottom air trench 125 exposing the piezoelectric layer 105.

The bottom air slot 125 is used for laterally reflecting the sound waves, thereby being beneficial to improving the residence time of the sound waves in the cavity, further reducing the energy dissipation, and correspondingly being beneficial to improving the acoustoelectric conversion performance of the resonator.

The first blocking layer reduces the probability of the second electrode 106 being etched after etching to form the etch mask of the bottom air trench 125.

In this embodiment, a spin coating process is used to form the first shielding layer.

In this embodiment, the second electrode 106 is etched by a dry etching process using the first shielding layer as a mask, thereby forming a bottom air groove 125 exposing the piezoelectric layer 105. The dry etching process is an anisotropic etching process, has good etching profile controllability, is favorable for enabling the morphology of the bottom air groove 125 to meet the process requirements, reduces the damage to other film layer structures, and is favorable for improving the removal efficiency of the first shielding material layer.

The method of forming the resonator further includes: after the bottom air trench 125 is formed, the first mask layer is removed.

Referring to fig. 8, a first substrate 112 is bonded on a first support layer 111, and the first substrate 112, the second electrode 106, and the first support layer 111 enclose a first cavity 113.

The first cavity 113 is advantageous for reducing the vibration energy loss of the resonator, and can improve the acoustoelectric conversion performance of the resonator.

The first substrate 112 may be any suitable substrate known to those skilled in the art, and may be, for example, at least one of the following materials: silicon, germanium, silicon carbon, silicon germanium carbon, indium arsenide, gallium arsenide, indium phosphide, or other III/V compound semiconductors, and also includes a multilayer structure formed of these semiconductors, or silicon on insulator, silicon germanium on insulator, and germanium on insulator, or may be Double-Side Polished silicon Wafers (DSPs), or may be ceramic substrates such as aluminum oxide, quartz, glass substrates, or the like.

Referring to fig. 9, the method of forming the resonator further includes: after the first cavity 113 is formed, the temporary substrate 100 and the first buffer layer 101 are removed.

In this embodiment, the temporary substrate 100 may be removed by a thinning process or a peeling process.

In this embodiment, the first buffer layer 101 is removed by a process combining a dry process and a wet process. Specifically, a wet etching process is used to remove a part of the first buffer layer 101, and after removing a part of the first buffer layer 101, a dry etching process is used to remove the remaining first buffer layer 101.

In this embodiment, after the first buffer layer 101 with a partial thickness is removed by a wet etching process, the first buffer layer 101 with a partial thickness remains on the first electrode 104. The second metal layer 102 is arranged in the first electrode 104 and close to the first buffer layer 101, and in the step of removing the remaining first buffer layer 101 by adopting the dry etching process, the etching difficulty of the first buffer layer 101 is greater than that of the second metal layer 102, so that the damage of the corresponding first electrode 104 is small.

Referring to fig. 10 to 12, the method of forming the resonator further includes: after bonding the first substrate 112 and the first support layer 111, etching the first electrode 104 and the piezoelectric layer 105 from the surface of the first electrode 104 opposite to the piezoelectric layer 105 to expose the second metal layer 102 in the second electrode 106, and forming a first trench 116 (shown in fig. 10) and a second trench 117 (shown in fig. 10); a first signal electrode 118 is formed in the first trench 116 (as shown in fig. 12), and a second signal electrode 119 is formed in the second trench 17 (as shown in fig. 12).

During operation of the resonator, the first signal electrode 118 and the second signal electrode 119 are used for input and output of signals, respectively.

In this embodiment, a dry etching process is used to etch the first electrode 104 and the piezoelectric layer 105 from the surface of the first electrode 104 opposite to the piezoelectric layer 105, so as to expose the second metal layer 102 in the second electrode 106, and form a first trench 116 and a second trench 117. The dry etching process has anisotropic etching characteristics and good etching profile controllability, so that the shapes of the first trench 116 and the second trench 117 can meet the process requirements, and the top of the second metal layer 102 in the second electrode 106 can be used as an etching stop position in the process of forming the first trench 116 and the second trench 117 by adopting the dry etching process.

In this embodiment, the step of forming the first signal electrode 118 and the second signal electrode 119 includes: forming a conductive material layer 120 conformally covering the first and

second trenches

116, 117 and the first electrode 104, patterning the conductive material layer 120, leaving the conductive material layer 120 in the first trench 116 as a first signal electrode 118 and the conductive material layer 120 in the second trench 17 as a second signal electrode 119.

In this embodiment, the material of the first signal electrode 118 and the second signal electrode 119 is copper. In other embodiments, the first signal electrode and the second signal electrode may be other types of metal materials.

The method for forming a resonator further includes: after forming the first signal electrode 118 and the second signal electrode 119, a side of the first signal electrode 118 facing away from the piezoelectric layer 105 is etched to form a Top Air Trench (TAT) 126 exposing the piezoelectric layer 105, and a projection of the Top Air Trench 126 on the first substrate 112 is located between projections of the first signal electrode 118 and the second signal electrode 119 on the first substrate.

The top air groove 126 is used for transversely reflecting the sound wave, so that the residence time of the sound wave in the subsequently formed second cavity is prolonged, the energy dissipation is reduced, and the acoustic-electric conversion performance of the resonator is improved correspondingly. In other embodiments, the second trench can also be used to define the edge of the active region of the resonator, i.e. the edge of the region where the resonator selects effective resonance; the top air slot and the bottom air slot together define an area of effective resonance.

The method of forming the top air slot 126 further includes: forming a second shielding layer (not shown) covering the first signal electrode 118, the second signal electrode 119, and the first electrode 104, filling the first opening 110, the second shielding layer including an organic material layer, an anti-reflective coating on the organic material layer, and a photoresist layer on the anti-reflective coating; the first electrode 104 is etched using the second masking layer as a mask to form a top air trench 126 exposing the piezoelectric layer 105.

The second masking layer reduces the probability of the first electrode 104 being etched after etching to form the etch mask for the top air trench 126.

In this embodiment, the second shielding layer is formed by a spin coating process.

In this embodiment, the first electrode 104 is etched by a dry etching process using the second masking layer as a mask, so as to form a top air trench 126 exposing the piezoelectric layer 105. The dry etching process is an anisotropic etching process, has good etching profile controllability, is favorable for enabling the appearance of the top air groove 126 to meet the process requirements, reduces the damage to other film layer structures, and is favorable for improving the removal efficiency of the second shielding material layer.

The method of forming the resonator further includes: after the top air trench 126 is formed, the second masking layer is removed.

Referring to fig. 13 and 14, the method of forming the resonator further includes: providing a second substrate 122; forming a second support material layer (not shown) on the second substrate 122; patterning the second supporting material layer to form a second opening 123 exposing the second substrate 122, and using the remaining second supporting material layer as a second supporting layer 121; the second opening 123 is directed towards the side of the first electrode 104 facing away from the piezoelectric layer 105, so that the second support layer 121 is bonded to the first electrode 104, and the second substrate 122, the first electrode 104 opposite the second substrate 122 and the second support layer 121 enclose a second cavity 124.

The second cavity 124 is beneficial to reducing the vibration energy loss of the resonator, and can improve the acoustoelectric conversion performance of the resonator.

The second substrate 122 is prepared for forming the second support layer 121.

The second substrate 122 may be any suitable substrate known to those skilled in the art, and may be, for example, at least one of the following materials: silicon, germanium, silicon carbon, silicon germanium carbon, indium arsenide, gallium arsenide, indium phosphide, or other III/V compound semiconductors, and a multilayer structure formed of these semiconductors, or silicon on insulator, silicon germanium on insulator, and germanium on insulator, or a double-side polished silicon wafer, or a ceramic substrate such as alumina, a quartz substrate, a glass substrate, or the like.

The second support layer 121 is a deformable material. Specifically, the material of the second support layer 121 may be an organic material having strong adhesiveness. In this embodiment, the material of the second support layer 121 is a Dry film (Dry film).

In this embodiment, the second support layer 121 is bonded to the first electrode 104 using a bonding process.

Specifically, in this embodiment, the second cavity 124 is enclosed by the second substrate 122, the second support layer 121, the first signal electrode 118, and the second signal electrode 119.

Referring to fig. 15 and 16, the method of forming the resonator further includes: after the second cavity 124 is formed, the first substrate 112 and the first supporting layer 111 are etched, and a conductive through hole 127 exposing the second metal layer 102 in the first electrode 104 is formed; an interconnect structure 128 is formed in the conductive via 127 in contact with the second metal layer 102 in the first electrode 104.

Interconnect structure 128 is prepared for subsequent packaging processes. In this embodiment, the interconnection structure 128 is in contact with the second metal layer 120 with a smaller residual resistivity, and when the resonator works, the interconnection structure 128 and the second metal layer 120 have a smaller contact resistance, which is beneficial to reducing the energy consumption of the resonator and improving the electrical performance of the resonator.

In this embodiment, a dry etching process is used to etch the first substrate 112 and the first supporting layer 111, and a conductive via 127 exposing the second metal layer 102 in the first electrode 104 is formed. The dry etching process has anisotropic etching characteristics and good etching profile controllability, is beneficial to enabling the appearance of the conductive through hole 127 to meet the process requirements, and can use the top of the second metal layer 102 in the first electrode 104 as an etching stop position in the process of forming the conductive through hole 127 by adopting the dry etching process, thereby reducing the damage to other film layer structures. Moreover, by replacing the etching gas, the second buffer layer 115, the etch stop layer 114, and the top layer 113 can be etched in the same etching apparatus, simplifying the process steps.

In the present embodiment, the material of the interconnect structure 128 includes Cu.

In this embodiment, the interconnect structure 128 is formed using a physical vapor deposition process. The physical vapor deposition process has the advantages of simple process, less pollution, low process cost, compact formed film, strong bonding force with other film structures and the like.

In particular, the projection of the bottom of interconnect structure 128 onto first substrate 112 corresponds to the projection of first signal electrode 118 and second signal electrode 119 onto first substrate 112.

In other embodiments, the first electrode or the second electrode in the resonator is a composite laminate, and the other electrode has a single-layer structure.

When the first electrode or the second electrode is a composite lamination, the other electrode is a first metal layer or a second metal layer, and because the resistivity of the material corresponding to the second metal layer is smaller than that of the material corresponding to the first metal layer, compared with the case that the first electrode and the second electrode only comprise the first metal layer, because the total resistance of the first electrode and the second electrode is smaller, the insertion loss of the resonator can be reduced in the process that signals pass through the resonator, and the performance of the resonator is improved. And the first electrode or the second electrode is a composite lamination, and the other electrode is a single-layer structure, so that the forming efficiency of the resonator is improved, and the forming process of the resonator is simplified.

Specifically, when the first electrode is a composite laminate and the second electrode is a first metal layer or a second metal layer, in other embodiments, the second electrode may also be a metal with other composite process conditions.

When the second electrode is a composite lamination, the second electrode is a first metal layer or a second metal layer, and the first electrode can also be a metal with other composite process conditions.

Correspondingly, the invention also provides a resonator. With continued reference to fig. 16, a schematic structural diagram of an embodiment of the resonator of the present invention is shown.

The resonator includes: a first electrode 104; a piezoelectric layer 105 on the first electrode 104; a second electrode 106 on the piezoelectric layer 105; one or both of the first electrode 104 and the second electrode 106 is a composite laminate including a first metal layer 103 opposite to the piezoelectric layer 105 and a second metal layer 102 on a side of the first metal layer 103 facing away from the piezoelectric layer 105, the surface roughness of the first metal layer 103 is smaller than that of the second metal layer 102, and the resistivity of the first metal layer 103 is greater than that of the second metal layer 102.

When the first electrode 104 and the second electrode 106 are both composite laminates, because the resistivity of the material corresponding to the second metal layer 102 is smaller than the resistivity of the material corresponding to the first metal layer 103, the total resistance of the first electrode 104 and the second electrode 106 is smaller than the case where the first electrode 104 and the second electrode 106 include only the first metal layer 103; in addition, in the process of forming the piezoelectric layer 105 on the first electrode 104, the piezoelectric layer 105 is formed on the first metal layer 103 with small surface roughness, so that the uniformity of the crystal growth direction of the piezoelectric layer 105 is good, and the forming quality of the piezoelectric layer 105 is good; in summary, in the process of passing a signal through the resonator, the total resistance of the first electrode 104 and the second electrode 106 is small, and the quality of the piezoelectric layer 105 is good, so that the insertion loss of the resonator can be reduced, and the performance of the resonator can be improved.

The second electrode 106 and the first electrode 104 are used to convert the mechanical vibration generated by the piezoelectric layer 105 into an electrical signal.

In this embodiment, the resistivity of second metal layer 102 is less than 5.2 Ω/m. The resistivity of the second metal layer 102 is small, which is beneficial to making the resistance of the first electrode 104 formed by the second metal layer 102 and the first metal layer 103 small, so that the resistance of the first electrode 104 meets the working requirement.

It should be noted that second metal layer 102 is not too thick nor too thin. If second metal layer 102 is too thick, it takes too much process time to form second metal layer 102, the forming efficiency of the second metal layer 102 is not easily improved, and if the second metal layer 102 is too thick, the corresponding first electrode 104 and the second electrode 106 are too thick, which easily causes the volume of the resonator to be too large, and is not favorable for improving the quality factor of the resonator. The resistivity of the second metal layer 102 is smaller than that of the first metal layer 103, and if the second metal layer 102 is too thin, the resistances of the first electrode 104 and the second electrode 106 formed by the second metal layer 102 and the first metal layer 103 are easily larger, and the resistance of the first electrode 104 is not easy to meet the working requirement. In this embodiment, the thickness of the second metal layer 102 is

To

The surface roughness of the first metal layer 103 is less than the surface roughness of the second metal layer 102.

Generally, the piezoelectric layer 105 is formed on the first electrode 104, specifically, on the first metal layer 103, and the surface roughness of the first metal layer 103 is small, so that a better interface state can be provided for forming the piezoelectric layer 105, the piezoelectric layer 105 can have a crystal orientation with better consistency, and the formation quality of the piezoelectric layer 105 can be improved; usually, the second metal layer 102 in the second electrode 106 is formed on the first metal layer 103 in the second electrode 106, and the surface roughness of the first metal layer 103 is small, so that a better interface state can be provided for forming the second metal layer 102, the second metal layer 102 can have a crystal orientation with better consistency, and the formation quality of the second metal layer 102 can be improved. When the resonator works, signals pass through the resonator, and the phenomenon of large insertion loss is not easy to cause.

It should be noted that the surface roughness of the first metal layer 103 is not excessively large. If the surface roughness of the first metal layer 103 is too large, it is not easy to provide a better interface state for forming the piezoelectric layer 105, resulting in a poor formation quality of the piezoelectric layer 105, and it is also not easy to provide a better interface state for forming the second metal layer 102 in the second electrode 106, resulting in a poor formation quality of the second metal layer 102 in the second electrode 106, resulting in a second electrode 106The second metal layer 102 in (2) has a relatively high resistivity, and when the resonator operates, a signal passes through the resonator, which easily causes a phenomenon of large insertion loss. In this embodiment, the surface roughness of the first metal layer 103 is less than

It should be noted that the first metal layer 103 is not too thick nor too thin. If the first metal layer 103 is too thick, too much process time is required to form the first metal layer 103, which is not easy to improve the forming efficiency of the first metal layer 103, and if the first metal layer 103 is too thick, the corresponding first electrode 104 and the second electrode 106 are too thick, which is easy to cause the volume of the resonator to be too large, and is not favorable for improving the quality factor of the resonator. If the first metal layer 103 is too thin, it is not easy to provide a better interface state for forming the piezoelectric layer 105, resulting in poor quality of the formed piezoelectric layer 105 and the second metal layer 102 in the second electrode 106, and when the resonator is in operation, a signal passes through the resonator, which is likely to cause a phenomenon of large insertion loss. In this embodiment, the thickness of the first metal layer 103 is

To

The resonator further includes: a first supporting layer 111 located on a side of the second electrode 106 opposite to the piezoelectric layer 105, wherein a first opening exposing the second electrode 106 is formed in the first supporting layer 111; the first substrate 112 is disposed on the first support layer 111, and the second electrode 106, the first support layer 111, and the first substrate 112 define a first cavity 113.

The material of the first support layer 111 includes: a second buffer layer 115, an etch stop layer 114 on a side of the second buffer layer 115 facing away from the piezoelectric layer 105, and a top layer 113 on a side of the etch stop layer 114 facing away from the piezoelectric layer 105.

In this embodiment, the material of the top layer 113 includes: one or more of tetraethyl orthosilicate (TEOS), silicon oxide, silicon nitride, aluminum oxide and aluminum nitride.

In this embodiment, the material of the second buffer layer 115 includes tetraethyl orthosilicate (TEOS). In other embodiments, the material of second buffer layer 115 includes: silicon oxide.

In the present embodiment, the material of the etch stop layer 114 includes, but is not limited to, silicon nitride and silicon oxynitride.

The bottom surface of the first cavity 113 may be rectangular or polygonal other than rectangular, for example, pentagonal, hexagonal, octagonal, or the like, and may be circular or elliptical. In other embodiments, the longitudinal cross-sectional shape of the first cavity may also be a spherical cap with a wide top and a narrow bottom, i.e. the longitudinal cross-section of the first cavity is U-shaped.

A bottom air groove 125 located on a side of the second electrode 106 facing away from the piezoelectric layer 105, the bottom air groove 125 exposing the piezoelectric layer 105, a projection of the bottom air groove 125 on the first substrate 112 being located between the first signal electrode 118 and a projection of the second signal electrode 119 on the first substrate 112.

The resonator further includes: a second support layer 121, located on a side of the first electrode 104 opposite to the piezoelectric layer 105, wherein a second opening exposing the first electrode 104 is formed in the second support layer 121; and a second substrate 122 located on a side of the second support layer 121 away from the first electrode 104, wherein the second substrate 122, the second support layer 121 and the second electrode 106 enclose a second cavity 124.

The second cavity 124 releases the pressure in the first cavity 113 located below the piezoelectric layer 105, so as to prevent the film bulk acoustic resonator from bending due to the pressure, and further improve the quality factor of the film bulk acoustic resonator.

In this embodiment, the second supporting layer 121 is a deformable material. Specifically, the material of the second support layer 121 may be an organic material having strong adhesiveness.

In this embodiment, the material of the second support layer 121 is a Dry film (Dry film).

In this embodiment, the second substrate 122 may be any suitable substrate known to those skilled in the art, and may be at least one of the following materials: silicon, germanium, silicon carbon, silicon germanium carbon, indium arsenide, gallium arsenide, indium phosphide, or other III/V compound semiconductors, and a multilayer structure formed of these semiconductors, or silicon on insulator, silicon germanium on insulator, and germanium on insulator, or a double-side polished silicon wafer, or a ceramic substrate such as alumina, a quartz substrate, a glass substrate, or the like.

The resonator further includes: a first trench 116 (shown in fig. 10) and a second trench 117 (shown in fig. 10) on a side of the first electrode 104 facing away from the piezoelectric layer 105, the first trench 116 and the second trench 117 penetrating the first electrode 104 and the piezoelectric layer 105 to expose the second metal layer 102 in the second electrode 106; a first signal electrode 118 is located in the first trench 116 and a second signal electrode 119 is located in the second trench 117.

The resonator further includes: a top air groove 126 located in the first electrode 104 on a side facing away from the piezoelectric layer 105, the top air groove 126 exposing the piezoelectric layer 105, a projection of the top air groove 126 on the first substrate 112 being located between the first signal electrode 118 and a projection of the second signal electrode 119 on the first substrate 112.

The resonator further includes: and an interconnection structure 128 penetrating the first substrate 112 and the first support layer 111 and contacting the second metal layer 102 in the first electrode 104.

Interconnect structure 128 is ready for subsequent packaging. In the present embodiment, the material of the interconnect structure 128 includes Cu.

When the first electrode or the second electrode is a composite lamination, the other electrode is a first metal layer or a second metal layer, and because the resistivity of the material corresponding to the second metal layer is smaller than that of the material corresponding to the first metal layer, compared with the case that the first electrode and the second electrode only comprise the first metal layer, the total resistance of the first electrode and the second electrode is smaller, the insertion loss of the resonator can be reduced in the process that signals pass through the resonator, and the performance of the resonator is improved. And the first electrode or the second electrode is a composite lamination, and the other electrode is a single-layer structure, so that the forming efficiency of the resonator is improved, and the forming process of the resonator is simplified.

The resonator may be formed by the method for forming the resonator according to the foregoing embodiment, or may be formed by another method for forming the resonator. In this embodiment, for the specific description of the resonator, reference may be made to the corresponding description in the foregoing embodiments, and the description of this embodiment is not repeated herein.

Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A resonator, comprising:

a first electrode;

a piezoelectric layer on the first electrode;

a second electrode on the piezoelectric layer;

one or two of the first electrode and the second electrode are composite laminated layers, each composite laminated layer comprises a first metal layer opposite to the piezoelectric layer and a second metal layer located on one side, opposite to the piezoelectric layer, of the first metal layer, the surface roughness of the first metal layer is smaller than that of the second metal layer, and the resistivity of the first metal layer is larger than that of the second metal layer.

2. The resonator of claim 1, further comprising: the first support layer is positioned on one side, back to the piezoelectric layer, of the second electrode, and a first opening for exposing the second electrode is formed in the first support layer;

the first substrate is positioned on the first support layer, and the second electrode, the first support layer and the first substrate enclose a first cavity.

3. The resonator of claim 2, further comprising: the second supporting layer is positioned on one side, opposite to the piezoelectric layer, of the first electrode, and a second opening for exposing the first electrode is formed in the second supporting layer;

and the second substrate is positioned on one side of the second supporting layer, which is far away from the first electrode, and the second substrate, the second supporting layer and the second electrode enclose a second cavity.

4. The resonator of claim 3, wherein the second electrode is a composite laminate;

the resonator further includes: the first groove and the second groove are positioned on one side, opposite to the piezoelectric layer, of the first electrode, penetrate through the first electrode and the piezoelectric layer, and expose the second metal layer in the second electrode;

a first signal electrode is positioned in the first groove;

a second signal electrode in the second trench.

5. The resonator of claim 1, wherein the first electrode or second electrode is a composite stack, the first electrode is the composite stack, and the second electrode is a first metal layer or a second metal layer;

the first electrode or the second electrode is a composite lamination, the second electrode is the composite lamination, and the second electrode is a first metal layer or a second metal layer.

6. The resonator of claim 4,

the resonator further includes: a bottom air groove located on a side of the second electrode facing away from the piezoelectric layer and exposing the piezoelectric layer, a projection of the bottom air groove on the first substrate being located between projections of the first and second signal electrodes on the first substrate;

the resonator further includes: a top air slot located in the first electrode on a side facing away from the piezoelectric layer and exposing the piezoelectric layer, a projection of the top air slot on the first substrate being located between projections of the first and second signal electrodes on the first substrate.

7. The resonator of any of claims 1-6, wherein the first metal layer has a surface roughness less than

8. The resonator of any of claims 1-6, wherein the material of the first metal layer comprises one or both of W and Mo.

9. The resonator of any of claims 1-6, wherein the resistivity of the second metal layer is less than 5.2 Ω/m.

10. The resonator of any of claims 1-6, wherein the material of the second metal layer comprises one or more of Al, Au, Ni, and Ag.

11. A method of forming a resonator, comprising:

forming a first electrode;

forming a piezoelectric layer on the first electrode;

forming a second electrode on the piezoelectric layer;

12. The method of forming a resonator according to claim 11, further comprising:

forming a first support material layer on the second electrode;

patterning the first support material layer to form a first opening which penetrates through the first support material layer and exposes the second electrode, wherein the rest of the first support material layer is used as a first support layer;

and bonding a first substrate on the first support layer, wherein the first substrate, the second electrode and the first support layer enclose a first cavity.

13. The method of forming a resonator according to claim 12, further comprising:

providing a second substrate;

forming a second layer of support material on the second substrate;

patterning the second support material layer to form a second opening exposing the second substrate, wherein the rest of the second support material layer is used as a second support layer;

and the second opening faces the surface of the first electrode, which faces away from the piezoelectric layer, so that the second support layer is combined with the first electrode, and the second substrate, the first electrode opposite to the second substrate and the second support layer enclose a second cavity.

14. The method of forming a resonator of claim 13, wherein the second electrode is a composite laminate;

the method for forming the resonator further comprises the following steps: after the first substrate is bonded with the first support layer, bonding the second substrate before the side of the first electrode, which faces away from the piezoelectric layer, is bonded with the first electrode, etching the first electrode and the piezoelectric layer from the surface of the first electrode, which faces away from the piezoelectric layer, exposing the second metal layer in the second electrode, and forming a first groove and a second groove;

forming a first signal electrode in the first trench;

a second signal electrode is formed in the second trench.

15. The method of forming a resonator according to claim 11, wherein in the step of forming the first electrode or the second electrode, the first electrode or the second electrode is a composite laminate;

the first electrode is the composite laminate, and the second electrode is a first metal layer or a second metal layer;

or, the second electrode is the composite laminate, and the second electrode is a first metal layer or a second metal layer.

16. The method of forming a resonator according to claim 14, further comprising:

after the first opening is formed, etching the second electrode exposed out of the first opening to form a bottom air groove exposing the piezoelectric layer;

and after the first signal electrode and the second signal electrode are formed, etching one side of the first signal electrode, which is far away from the piezoelectric layer, to form a top air groove exposing the piezoelectric layer, wherein the projection of the top air groove on the first substrate is positioned between the projections of the first signal electrode and the second signal electrode on the first substrate.

17. The method of forming a resonator of any of claims 13-16, wherein the first metal layer has a surface roughness less than

18. The method of forming a resonator of any of claims 13-16, wherein the material of the first metal layer comprises one or both of W and Mo.

19. The method of forming a resonator according to any of claims 13 to 16, wherein in the step of forming the second metal layer, the second metal layer has a resistivity of less than 5.2 Ω/m.

20. The method of forming a resonator according to any of claims 13 to 16, wherein the material of the second metal layer comprises one or more of Al, Au, Ni and Ag.