CN116707472A

CN116707472A - Terminal, communication equipment, filter and forming method of filter

Info

Publication number: CN116707472A
Application number: CN202310699421.7A
Authority: CN
Inventors: 万晨庚
Original assignee: Beijing Xinxi Semiconductor Technology Co ltd
Current assignee: Beijing Xinxi Semiconductor Technology Co ltd
Priority date: 2023-06-13
Filing date: 2023-06-13
Publication date: 2023-09-05

Abstract

The embodiment of the application provides a terminal, communication equipment, a filter and a forming method thereof, wherein the filter comprises the following components: the resonant structure comprises a substrate, a bottom electrode, a piezoelectric layer and a top electrode, wherein the substrate comprises a cavity part, the bottom electrode is arranged above the cavity part, a first cavity is formed between the bottom electrode and the cavity part, the piezoelectric layer is arranged above the bottom electrode, and the top electrode is arranged above the piezoelectric layer; the first conductive plug is arranged above the bottom electrode and is electrically connected with the bottom electrode; the second conductive plug is arranged above the top electrode and is electrically connected with the top electrode; the substrate is arranged above the first conductive plug and the second conductive plug, is electrically connected with the first conductive plug and the second conductive plug, and forms a second cavity with the upper surfaces of the first conductive plug, the second conductive plug and the resonance structure. The communication equipment, the filter and the forming method thereof provided by the embodiment of the application have the advantage that the filter has smaller volume.

Description

Terminal, communication equipment, filter and forming method of filter

Technical Field

The embodiment of the application relates to the technical field of semiconductors, in particular to a terminal, communication equipment, a filter and a forming method thereof.

Background

With the development of technologies such as the internet and artificial intelligence, research on semiconductor devices is getting more and more important, and a filter is an important component of a radio frequency front end, and is a device for eliminating interference in a communication system, and plays an important role in the communication system.

With the advent of the 5G era, terminals such as mobile phones need to meet multiple bands of 3G,4G,5G and multiple operators, so at least 50 filters are generally required to meet the radio frequency requirements of terminals such as mobile phones, but at present, pursuit of light weight and thin and light weight of various wireless terminals is more and more urgent, and new requirements are put forth on the packaging volumes of various electronic elements.

Therefore, how to reduce the volume of the filter is a technical problem to be solved.

Disclosure of Invention

In view of the above, embodiments of the present application provide a terminal, a communication device, a filter and a forming method thereof, so as to reduce the volume of the filter.

To solve the above problems, an embodiment of the present application provides a filter including:

the resonant structure comprises a substrate, a bottom electrode, a piezoelectric layer and a top electrode, wherein the substrate comprises a cavity part, the bottom electrode is arranged above the cavity part, a first cavity is formed between the bottom electrode and the cavity part, the piezoelectric layer is arranged above the bottom electrode, and the top electrode is arranged above the piezoelectric layer;

The first conductive plug is arranged above the bottom electrode and is electrically connected with the bottom electrode;

the second conductive plug is arranged above the top electrode and is electrically connected with the top electrode;

the substrate is arranged above the first conductive plug and the second conductive plug, is electrically connected with the first conductive plug and the second conductive plug, and forms a second cavity with the upper surfaces of the first conductive plug, the second conductive plug and the resonance structure.

Optionally, the upper and lower surfaces of the piezoelectric layer are planar.

Optionally, the substrate is provided with a substrate cavity, the bottom wall of the substrate cavity is the cavity part, the bottom electrode is arranged above the substrate, and the bottom electrode and the substrate form the first cavity.

Optionally, the substrate is provided with a substrate cavity, the bottom wall of the substrate cavity is the cavity part, the bottom electrode is provided with a bottom isolation groove, at least part of the side wall of the substrate cavity passes through the bottom isolation groove to support the piezoelectric layer, and at least the bottom electrode and the substrate form the first cavity.

Optionally, the resonant structure further comprises:

the insulating supporting layer is arranged above the substrate and provided with a supporting cavity, and the substrate corresponding to the supporting cavity is the cavity part;

The bottom electrode is arranged above the insulating support layer, and the insulating support layer, the bottom electrode and the cavity part form the first cavity.

Optionally, the resonant structure further comprises:

the bottom electrode is provided with a bottom isolation groove, at least part of the insulating supporting layer penetrates through the bottom isolation groove to support the piezoelectric layer, and the insulating supporting layer at least forms the first cavity together with the bottom electrode and the cavity part.

Optionally, the resonant structure further comprises:

the top electrode protection layer is arranged above the top electrode;

the first conductive plug passes through at least one layer of the top electrode protection layer, the top electrode and the piezoelectric layer to be electrically connected with the bottom electrode, and the second conductive plug passes through the top electrode protection layer to be electrically connected with the top electrode.

Optionally, the resonant structure further comprises:

and the bottom electrode protection layer is arranged below the bottom electrode.

Optionally, the first conductive plug includes:

a first conductive support post passing through the top electrode and the piezoelectric layer and electrically connected with the bottom electrode;

The first packaging solder ball is electrically connected with the first conductive support column and is electrically connected with the substrate.

Optionally, the second conductive plug includes:

a second conductive support post electrically connected to the top electrode;

and the second packaging solder balls are electrically connected with the second conductive support columns and the substrate.

Optionally, the method further comprises:

and the protective film is used for coating the substrate, covering the substrate which does not correspond to the substrate and sealing and connecting the protective film and the substrate.

Optionally, the method further comprises:

and a first rewiring layer disposed between the first conductive plug and the bottom electrode and electrically connecting the first conductive plug and the bottom electrode.

Optionally, the method further comprises:

and a second rewiring layer disposed between the second conductive plug and the top electrode and electrically connecting the second conductive plug and the top electrode.

The present application also provides a method for forming a filter to solve the foregoing problem, including:

forming a resonance structure, wherein the resonance structure comprises a substrate, a bottom electrode, a piezoelectric layer and a top electrode, the substrate comprises a cavity part, the bottom electrode is arranged above the cavity part, a first cavity is formed between the bottom electrode and the cavity part, the piezoelectric layer is arranged above the bottom electrode, and the top electrode is arranged above the piezoelectric layer;

Forming a first conductive plug and a second conductive plug on the resonance structure, wherein the first conductive plug is positioned above the bottom electrode and is electrically connected with the bottom electrode, and the second conductive plug is positioned above the top electrode and is electrically connected with the top electrode;

and electrically connecting a substrate with the first conductive plug and the second conductive plug, so that a second cavity is formed between the substrate and the upper surfaces of the first conductive plug, the second conductive plug and the resonance structure.

Optionally, the step of forming the resonant structure includes:

providing a support substrate;

sequentially forming a top electrode layer, a piezoelectric material layer and the bottom electrode on the support substrate;

providing the substrate and bonding so that the first cavity is formed between the bottom electrode and the cavity portion of the substrate;

removing the support substrate;

and removing part of the top electrode layer, forming the top isolation groove on the top electrode layer to obtain the top electrode, and forming the conductive through hole on the piezoelectric material layer to form the piezoelectric layer.

Optionally, the step of providing the substrate and bonding includes:

providing the substrate, wherein a substrate cavity is formed in the substrate, and the bottom wall of the substrate cavity is the cavity part;

And bonding the bottom electrode and the side wall of the substrate cavity so that the bottom electrode and the substrate form the first cavity.

Optionally, the bottom electrode is provided with a bottom isolation groove, and the step of providing the substrate and bonding includes:

at least the piezoelectric material layer and sidewalls of the substrate cavity are bonded such that the bottom electrode, the piezoelectric material layer and the substrate form the first cavity.

Optionally, the step of providing the substrate and bonding further includes, before:

forming an insulating support layer on the bottom electrode, wherein the insulating support layer is provided with a support cavity;

the step of providing the substrate and bonding includes:

providing the substrate;

and bonding the insulating support layer and the substrate to form the first cavity between the bottom electrode and the cavity part, wherein the substrate corresponding to the support cavity is the cavity part.

Optionally, the bottom electrode is provided with a bottom isolation groove, and before the step of providing the substrate and bonding, the method further comprises:

forming an insulating support layer on the piezoelectric material layer corresponding to at least the bottom isolation groove, wherein the insulating support layer is provided with a support cavity;

The step of providing the substrate and bonding includes:

providing the substrate;

Optionally, before the step of sequentially forming the top electrode layer, the piezoelectric material layer, and the bottom electrode on the support substrate, the method further includes:

forming a top electrode protection material layer on the support substrate;

the step of removing part of the top electrode layer, forming the top isolation groove on the top electrode layer, and obtaining the top electrode further comprises the following steps:

removing part of the top electrode protection material layer, and forming a top conductive connecting groove and a top protection isolation groove on the top electrode protection material layer to obtain a top electrode protection layer, wherein the top protection isolation groove corresponds to the top isolation groove;

the step of forming a first conductive plug and a second conductive plug on the resonant structure includes:

and forming a first conductive plug and a second conductive plug on the resonance structure, wherein the first conductive plug passes through the top protection isolation groove, the top isolation groove and the conductive through hole to be electrically connected with the bottom electrode, and the second conductive plug passes through the top conductive connection groove to be electrically connected with the top electrode.

Optionally, the step of sequentially forming a top electrode layer, a piezoelectric material layer and the bottom electrode on the support substrate includes:

sequentially forming a top electrode layer, a piezoelectric material layer, a bottom electrode layer and a bottom electrode protection material layer on the support substrate;

removing part of the bottom electrode protection material layer, and forming a bottom protection isolation groove on the bottom electrode protection material layer to obtain a bottom electrode protection layer;

and removing part of the bottom electrode layer, and forming a bottom isolation groove on the bottom electrode layer to obtain the bottom electrode.

Optionally, the step of forming a first conductive plug on the resonant structure includes:

forming a first conductive support column, the first conductive support column being electrically connected to the bottom electrode;

welding a first packaging welding ball and the first conductive support column to obtain the first conductive plug;

the step of electrically connecting the substrate and the first conductive plug includes:

and welding the first packaging welding ball and the substrate, and electrically connecting the substrate and the first conductive plug.

Optionally, the step of forming a second conductive plug on the resonant structure includes:

forming a second conductive support post, the second conductive support post being electrically connected to the top electrode;

Welding a second packaging solder ball and the second conductive support column to obtain the second conductive plug;

the step of electrically connecting the substrate and the second conductive plug includes

And welding the second packaging solder ball and the substrate, and electrically connecting the substrate and the second conductive plug.

Optionally, the method further comprises:

and covering the substrate and the base plate with a protective film so that the protective film covers the substrate, covers the base plate which does not correspond to the substrate and is connected with the base plate in a sealing way.

Optionally, before the step of forming the first conductive plug on the resonant structure, the method further includes:

forming a first rewiring layer on the bottom electrode, the first rewiring layer being electrically connected to the bottom electrode;

the step of forming a first conductive plug on the resonant structure comprises:

the first conductive plug is formed on the first rewiring layer, and the first conductive plug is electrically connected with the first rewiring layer.

Optionally, before the step of forming the second conductive plug on the resonant structure, the method further includes:

forming a second rewiring layer on the top electrode, the second rewiring layer electrically connecting the top electrode;

The step of forming a second conductive plug on the resonant structure comprises:

the second conductive plug is formed on the second re-wiring layer, and the second conductive plug is electrically connected to the second re-wiring layer.

The present application also provides a communication device comprising a filter as claimed in any one of the preceding claims.

The application also provides a terminal comprising a filter as claimed in any one of the preceding claims to solve the aforementioned problems.

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

the filter provided by the embodiment of the application comprises a resonance structure, a first conductive plug, a second conductive plug and a substrate, wherein the resonance structure comprises a substrate, a bottom electrode, a piezoelectric layer and a top electrode, the substrate comprises a cavity part, the bottom electrode is arranged above the cavity part, a first cavity is formed between the bottom electrode and the cavity part, the piezoelectric layer is arranged above the bottom electrode, and the top electrode is arranged above the piezoelectric layer; the first conductive plug is arranged above the bottom electrode and is electrically connected with the bottom electrode; the second conductive plug is arranged above the top electrode and is electrically connected with the top electrode; the substrate is arranged above the first conductive plug and the second conductive plug, is electrically connected with the first conductive plug and the second conductive plug, and forms a second cavity with the first conductive plug and the second conductive plug. It can be seen that, in the filter provided by the embodiment of the application, on one hand, the substrate is used for forming the second cavity while being connected with the top electrode and the bottom electrode, and the resonant structure of the filter is not required to be packaged by using the cover wafer, so that the use of the wafer is reduced, the thickness of the filter can be reduced, and the volume of the filter is reduced; on the other hand, the number of the used wafers can be reduced, and the preparation process can be further reduced, so that the processing time and the cost can be reduced; in yet another aspect, the first conductive plug is located above the bottom electrode, the second conductive plug is located above the top electrode, no conductive holes are required to be opened in the substrate, and reliability of the obtained filter is improved while process difficulty is reduced.

Therefore, the filter provided by the embodiment of the application has smaller thickness and volume, fewer working procedures are needed in the processing process, only shorter processing time is needed, and the processing difficulty is lower, so that the processing cost can be reduced, and the reliability is improved.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only embodiments of the present application, and that other drawings can be obtained according to the provided drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of a filter;

FIG. 2 is a schematic diagram of a first structure of a filter according to an embodiment of the present application;

FIG. 3 is a schematic diagram of a second structure of a filter according to an embodiment of the present application;

FIG. 4 is a top view of a filter according to an embodiment of the present application;

fig. 5 to 15 are schematic structural diagrams of steps of a method for forming a filter according to an embodiment of the present application.

Detailed Description

The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

The filter is a filter circuit composed of resonators, connection structures of the resonators and necessary matching elements, and the matching elements comprise passive devices such as inductors, capacitors and the like. The filter can effectively filter the frequency points of the specific frequency or the frequencies outside the frequency points in the power line to obtain a power signal of the specific frequency or eliminate the power signal of the specific frequency. Thus, the filter is one of the essential key components in the communication system and can be used to make frequency selection, i.e. pass the desired power signal frequency while reflecting the undesired interference signal frequency.

To facilitate understanding of the overall structure and functional implementation of the filter, in one example, embodiments of the present invention are described in connection with the structure of a basic filter; referring to fig. 1, fig. 1 is a schematic structural diagram of a filter.

As shown in fig. 1, the filter includes:

a substrate 10 provided with a substrate cavity (not shown by a reference numeral);

a bottom electrode 17 located over the substrate cavity;

a piezoelectric layer 16 located above the bottom electrode 17 and the substrate 10;

a top electrode 14 located above the piezoelectric layer 16;

an insulating support layer 11 located above the piezoelectric layer 16 and supported on the piezoelectric layer 16 and/or the top electrode 14;

The cover wafer 01 is positioned above the insulating support layer 11, and forms a second cavity 30 together with the insulating support layer 11, the top electrode 14 and the piezoelectric layer 16;

a first conductive plug 18 located above the cap wafer 01 and electrically connected to the bottom electrode 17;

a second conductive plug 20 located above the cap wafer 01 and electrically connected to the top electrode 14;

a substrate 21 located above the first conductive plug 18 and the second conductive plug 20, electrically connected to the bottom electrode 17 through the first conductive plug 18, and electrically connected to the top electrode 14 through the second conductive plug 20;

the substrate 10 forms a first cavity 19 with the bottom electrode 17 and the piezoelectric layer 16.

Wherein the bottom electrode 17, the piezoelectric layer 16, the top electrode 14, the first cavity 19 and the second cavity 30 constitute the main part of the resonant structure.

In the filter formation process, a substrate 10 is provided first, and a substrate cavity is opened; then forming a resonance structure, for this purpose, firstly forming a sacrificial layer (removed during processing, not shown in the figure) in the substrate cavity, then forming a bottom electrode 17 on the sacrificial layer, forming a bottom isolation groove (not shown in the figure) on the right side of the bottom electrode 17 in the figure by removing part of the bottom electrode 17 in order to avoid connection of the bottom electrode 17 of different resonance structures to be isolated due to a plurality of resonance structures in the filter, forming a piezoelectric layer 16 above the substrate 10 and the bottom electrode 17, and forming a top electrode 14 above the piezoelectric layer 16; then, forming an insulating support layer 11, removing the sacrificial layer, forming a first cavity 19, and bonding a cap wafer (cap wafer) 01 on the insulating support layer 11 to form a second cavity 30; next, via holes are etched on the cap wafer 01, the respective bottom electrodes 17 and top electrodes 14 are connected by forming a re-wiring layer 35 by plating metal on the via holes, and the first conductive plugs 18 and the second conductive plugs 20 are prepared on the re-wiring layer 35, and finally, the first conductive plugs 18 and the second conductive plugs 20 are connected to the substrate 21.

It can be seen that in the process of forming the filter, on one hand, the CAP wafer (CAP wafer) 01 needs to be bonded to the insulating support layer 11, and meanwhile, the bottom electrode 17 and the top electrode 14 need to be electrically connected to the substrate 21, so that the structure of the filter is complex and the size is large.

However, various wireless terminals are increasingly required to be light and thin, and thus providing a suitable filter structure to reduce the size of the filter is a technical problem to be solved.

In order to reduce the size of the filter, the embodiment of the invention provides the filter, and the purpose of effectively reducing the size of the filter is achieved by improving the structure of the filter.

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention. Like elements are denoted by like reference numerals throughout the various figures. For clarity, the various features of the drawings are not drawn to scale. Furthermore, some well-known portions may not be shown. For the sake of simplicity, the intermediate structure of the half-filter obtained after several steps can be described in one figure.

It will be understood that when a layer, an area, or a structure of a device is described as being "on" or "over" another layer, another area, it can be referred to as being directly on the other layer, another area, or further layers or areas can be included between the other layer, another area, etc. And if the device is flipped, the one layer, one region, will be "under" or "beneath" the other layer, another region.

In the present application, the term "device structure" refers to a generic term for the entire semiconductor structure formed in the various steps of fabricating the filter, including all layers or regions that have been formed. Numerous specific details of the application, such as device structures, materials, dimensions, processing techniques and technologies, are set forth in the following description in order to provide a thorough understanding of the application. However, as will be understood by those skilled in the art, the present application may be practiced without these specific details.

Referring to fig. 2, fig. 2 is a schematic diagram of a first structure of a filter according to an embodiment of the application.

As shown in the drawing, the filter provided by the embodiment of the application includes:

a resonant structure including a substrate 10, a bottom electrode 17, a piezoelectric layer 16, and a top electrode 14, wherein the substrate 10 includes a cavity portion (not shown in the figure), the bottom electrode 17 is disposed above the cavity portion, a first cavity 19 is formed between the bottom electrode 17 and the cavity portion, the piezoelectric layer 16 is disposed above the bottom electrode 17, and the top electrode 14 is disposed above the piezoelectric layer 16;

A first conductive plug 18 disposed above the bottom electrode 17 and electrically connected to the bottom electrode 17;

a second conductive plug 20 disposed above the top electrode 14 and electrically connected to the top electrode 14;

the substrate 21 is disposed above the first conductive plug and the second conductive plug, electrically connected to the first conductive plug and the second conductive plug, and forms a second cavity 30 with the first conductive plug 18, the second conductive plug 20, and the upper surface of the resonant structure.

It is to be readily understood that, as used herein, the cavity portion refers to a portion of the substrate opposite to the first cavity, and is a portion of the substrate, where the substrate cavity may or may not be opened; when the substrate 10 is provided with the substrate cavity, the bottom wall or a part of the bottom wall of the substrate cavity is the cavity, and when the substrate 10 is not provided with the substrate cavity, a part not covered by other structural layers is the cavity.

It should be noted that, since a plurality of parallel stages or series stages are generally disposed in the filter, and each of the parallel stages or series stages includes at least one resonant structure (may also be referred to as a resonator), in order to achieve isolation between different resonant structures, the top electrode 14 is provided with a top isolation groove 141 (shown in fig. 11), and similarly, the bottom electrode 17 is also provided with a bottom isolation groove 171 (shown in fig. 7).

When the top isolation groove 141 is opened, in a specific embodiment, in order to facilitate the electrical connection between the first conductive plug 18 and the bottom electrode 17, the first conductive plug 18 may be made to pass through the top isolation groove 141; of course, in other embodiments, a through hole may be formed in the top electrode 14, and the first conductive plug 18 may pass through the through hole.

Of course, whether the first conductive plug 18 is electrically connected to the bottom electrode 17 in that way, it is necessary to ensure isolation between the first conductive plug 18 and the top electrode 14, and in this embodiment, it may be achieved by having the first conductive plug 18 smaller in size than the top isolation groove 141, so that air is present between the first conductive plug 18 and the top electrode 14, and in other embodiments, it may also be achieved by providing a dielectric material between the first conductive plug 18 and the top electrode 14.

In order to facilitate the electrical connection between the first conductive plug 18 and the bottom electrode 17, a conductive via 161 (shown in fig. 11) may be further formed on the piezoelectric layer 16, where the conductive via 161 is opposite to the top isolation trench 141 in this embodiment, so that the first conductive plug 18 may be electrically connected to the bottom electrode 17 through the top isolation trench 141 and the conductive via 161.

It will be readily appreciated that the opening of the bottom isolation groove 171 (shown in fig. 7) does not affect the electrical connection of the first conductive plug 18 to the bottom electrode 17 and the electrical connection of the second conductive plug 20 to the top electrode 14.

In addition, although a plurality of parallel or series stages are typically provided in the filter, each including at least one resonant structure (which may also be referred to as a resonator) therein, not every resonant structure need be electrically connected to the substrate 21 through the first and second conductive plugs 18 and 20. Referring to fig. 3 and fig. 4, fig. 3 is a schematic diagram of a second structure of a filter according to an embodiment of the present application, and fig. 4 is a top view of a filter according to an embodiment of the present application.

As can be seen from the figure, in this embodiment, although R1-Rnn resonant structures (resonators) are disposed in the filter, only the upper electrode 14 and the lower electrode 17 of the resonant structure R1, and the upper electrode 14 and the lower electrode 17 of the resonator Rn are electrically connected to the substrate 21 through the first conductive plug 18 and the second conductive plug 20, and the specific connection manner may be determined as required, which is not described herein.

In order to facilitate the electrical connection between the bottom electrode 17 and the first conductive plug 18, in another embodiment, please continue to refer to fig. 3, the filter provided by the embodiment of the present application may further include:

a first rewiring layer 31 provided between the first conductive plug 18 and the bottom electrode 17 and electrically connecting the first conductive plug 18 and the bottom electrode 17.

The material of the first re-wiring layer 31 may be molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, or a composite of the above metals, an alloy thereof, or the like.

The arrangement of the first rewiring layer 31 can conduct the signal of the bottom electrode 17 to the upper portion of the piezoelectric layer 16, so that the first conductive plug 18 is prevented from being formed in the piezoelectric layer 16, the preparation of the first conductive plug 18 is facilitated, the height difference of the first packaging solder balls 182 can be reduced due to the arrangement of the first rewiring layer 31, and the yield of the filter is improved.

Of course, in order to facilitate the electrical connection between the second conductive plug 20 and the top electrode 14, please continue to refer to fig. 3, the filter provided by the embodiment of the present application further includes:

a second rewiring layer 32 provided between the second conductive plug 20 and the top electrode 14 and electrically connecting the second conductive plug 20 and the top electrode 14.

The material of the second re-wiring layer 32 may be molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, or a composite of the above metals, an alloy thereof, or the like, and the material of the second re-wiring layer 32 may be the same as or different from the first re-wiring layer.

In addition, the "first cavity 19 is formed between the bottom electrode 17 and the cavity portion" described herein means that the first cavity 19 is formed therebetween, but other structures may be formed to form the first cavity 19; the phrase "the substrate 21 forms the second cavity 30 with the first conductive plug 18, the second conductive plug 20, and the upper surface of the resonant structure" as used herein means that the second cavity 30 is formed at least including the substrate 21, the first conductive plug 18, the second conductive plug 20, and the upper surface of the resonant structure.

In a specific embodiment, the substrate 10 is provided with a substrate cavity, the bottom wall of the substrate cavity is the cavity portion, the bottom electrode 17 is disposed above the substrate 10, and the bottom electrode 17 and the substrate 10 form the first cavity 19.

Specifically, the substrate cavity may be obtained by etching, and may specifically be a dry etching process or a wet etching process.

The bottom electrode 17 is arranged above the substrate 10, i.e. the side walls of the substrate cavity support the bottom electrode 17, such that the bottom electrode 17 and the substrate 10 (including the bottom wall of the substrate cavity and the side walls of the substrate cavity) form a first cavity 19.

Thus, by forming the first cavity 19 between the bottom electrode 17 and the substrate 10 by opening the substrate cavity on the substrate 10, the acquisition of the cavity necessary for the filter can be realized very simply, and the processing process can be simplified.

In another embodiment of the present disclosure, the substrate 10 is provided with a substrate cavity, a bottom wall of the substrate cavity is the cavity portion, the bottom electrode 17 is provided with a bottom isolation groove 171, at least a portion of a sidewall of the substrate cavity passes through the bottom isolation groove 171 to support the piezoelectric layer 16, and at least the bottom electrode and the substrate form the first cavity 19.

It will be readily appreciated that when the bottom electrode 17 is provided with the bottom isolation groove 171, the side walls of the substrate cavity may pass through the bottom isolation groove 171 to support the piezoelectric layer 16, and specifically may include that the side walls of the substrate cavity at each position to be supported all pass through the bottom isolation groove 171 to support the piezoelectric layer 16, and that the side walls of the substrate cavity at only a portion of the position to be supported all pass through the bottom isolation groove 171 to support the piezoelectric layer 16, with the remainder still supporting the bottom electrode 17.

Further, when the sidewall of the substrate cavity is supported on the piezoelectric layer 16 through the bottom isolation groove 171, both a case where the sidewall of the substrate cavity is abutted against the bottom electrode 17 and a case where there is a space between the sidewall of the substrate cavity and the bottom electrode 17 are included, and in the former case, the bottom electrode 17 and the substrate 10 form the first cavity 19, and in the latter case, the bottom electrode 17, the piezoelectric layer 16 and the substrate 10 form the first cavity 19, and thus, the "at least the bottom electrode 17 and the substrate 10 form the first cavity 19" described herein includes that the bottom electrode 17 and the substrate 10 form the first cavity 19; the bottom electrode 17, the piezoelectric layer 16 and the substrate 10 form said first cavity 19; and also other structures together form a first cavity 19.

In this way, the bottom electrode 17 is provided with the bottom isolation groove 171, at least part of the sidewall of the substrate cavity passes through the bottom isolation groove 171 to support the piezoelectric layer 16, so that space can be fully utilized, and electrical isolation between the bottom electrodes 17 is more sufficient.

However, under the influence of the material characteristics (such as silicon) of the substrate 10 at high temperature, the resistance of the substrate 10 may be reduced, which may reduce the performance of the filter, and in order to improve the high temperature stability of the filter, the embodiment of the present application further provides a filter, and please continue to refer to fig. 2, where the resonant structure may further include:

an insulating supporting layer 11 disposed above the substrate 10 and provided with a supporting cavity, wherein the substrate 10 corresponding to the supporting cavity is the cavity portion;

the bottom electrode 17 is disposed above the insulating support layer 11, and the insulating support layer 11, the bottom electrode 17, and the cavity portion form the first cavity 19.

The bottom electrode 17 is supported by the insulating support layer 11, and the support cavity provides a space for forming the first cavity 19, so that the insulating support layer 11, the bottom electrode 17, and the cavity portion form the first cavity 19.

The material of the insulating support layer 11 may be monocrystalline silicon, polycrystalline silicon, silicon oxide, silicon nitride, gallium arsenide, sapphire, quartz, silicon carbide, SOI, or the like.

The bottom electrode 17 is not in contact with the substrate 10, but in contact with the insulating support layer 11, so that different resonance structures of the filter can be better electrically isolated, the performance cannot be influenced by the change of the substrate 10 under the high temperature condition, and the high temperature stability of the filter and the performance of the filter can be improved.

In addition, in another embodiment, please continue to refer to fig. 2, when the resonant structure of the filter further includes an insulating support layer 11, and the insulating support layer 11 is disposed above the substrate 10, and a support cavity is formed, and the substrate 10 corresponding to the support cavity is the cavity portion, the positional relationship between the bottom electrode 17 and the insulating support layer 11 may be:

the bottom electrode 17 is provided with a bottom isolation groove 171, at least a part of the insulating support layer 11 passes through the bottom isolation groove 171 to support the piezoelectric layer 16, and the first cavity 19 is formed at least with the bottom electrode 17 and the cavity portion.

Also, when the bottom electrode 17 is provided with the bottom isolation groove 171, the insulating support layer 11 may pass through the bottom isolation groove 171 to support the piezoelectric layer 16, and specifically may include that the insulating support layer 11 at each position to be supported passes through the bottom isolation groove 171 to support the piezoelectric layer 16 (as shown in fig. 3), and that the insulating support layer 11 at only a portion of the positions to be supported passes through the bottom isolation groove 171 to support the piezoelectric layer 16, and that the rest of the insulating support layer 11 still supports the bottom electrode 17 (as shown in fig. 2).

Further, when the insulating support layer 11 is supported on the piezoelectric layer 16 through the bottom isolation groove 171, both the case where the insulating support layer 11 is supported on the piezoelectric layer 16 in close contact with the bottom electrode 17 and the case where there is a space between the insulating support layer 11 and the bottom electrode 17, in the former case, the bottom electrode 17, the insulating support layer 11, and the substrate 10 form the first cavity 19, and in the latter case, the bottom electrode 17, the piezoelectric layer 16, the insulating support layer 11, and the substrate 10 form the first cavity 19, and thus, the "forming the first cavity 19 with at least the bottom electrode 17 and the cavity portion" described herein includes the insulating support layer 11, the bottom electrode 17, and the substrate 10 forming the first cavity 19; the insulating support layer 11, the bottom electrode 17, the piezoelectric layer 16 and the substrate 10 form the first cavity 19; and also other structures together form a first cavity 19.

In this way, the bottom electrode 17 is provided with the bottom isolation groove 171, at least part of the insulating support layer 11 passes through the bottom isolation groove 171 to support the piezoelectric layer 16, so that not only the high temperature stability of the filter can be improved, but also the space can be more fully utilized, and the electrical isolation between the bottom electrodes 17 is more fully achieved.

It is to be readily understood that the aforementioned region where the second cavity 30, the top electrode 14, the piezoelectric layer 16, the bottom electrode 17 and the first cavity 19 overlap each other is an effective region of the resonant structure, specifically, the upper and lower extension regions shown as 100 in fig. 2, and the first cavity 19 and the second cavity 30 are structures necessary for the normal operation of the filter.

In particular, alternative materials for the substrate 10 may include single crystal silicon, gallium arsenide, sapphire, quartz, silicon carbide, SOI, etc., and the material of the substrate 10 may be a material suitable for process requirements or easy integration.

Alternative materials for the top electrode 14 may include molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, or the like, or combinations or alloys thereof, and the like.

Alternative materials for the piezoelectric layer 16 may include single crystal piezoelectric materials, polycrystalline piezoelectric materials, or rare earth doped materials containing certain atomic ratios of the above materials.

Wherein the single crystal piezoelectric material is selected from single crystal aluminum nitride, single crystal gallium nitride, single crystal lithium niobate, single crystal lead zirconate titanate (PZT), single crystal potassium niobate, single crystal quartz film, or single crystal lithium tantalate; polycrystalline piezoelectric material (corresponding to single crystal, non-single crystal material), optionally polycrystalline aluminum nitride, zinc oxide, PZT, etc.; the rare earth element doped material containing the above-mentioned material in a certain atomic ratio may be, for example, doped aluminum nitride containing at least one rare earth element such as scandium (Sc), yttrium (Y), magnesium (Mg), titanium (Ti), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), or the like.

The material of the bottom electrode 17 may be the same as that of the top electrode 14, and may be molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, or a composite of the above metals, an alloy thereof, or the like. However, it is readily understood that the top electrode 14 and bottom electrode 17 materials may also be different.

The first conductive plug 18 and the second conductive plug 20 serve as a supporting function and a conductive function between the substrate and the bare filter chip (structural member of the resonant structure), and the material thereof may be a metal having a conductive function, such as gold, aluminum, magnesium, tungsten, copper, titanium, or the like.

The substrate 21, a substrate structure composed of a resin material or a dielectric material or one of them, is provided with a conductive interface thereon.

As can be seen, in the filter provided in the embodiment of the present application, on one hand, when the substrate 21 is connected with the top electrode 14 and the bottom electrode 17, the substrate 21 is used to form the second cavity 30, so that the cover wafer is not required to be used to package the resonant structure of the filter, the use of the wafer is reduced, and the thickness of the filter can be reduced, thereby reducing the volume of the filter; on the other hand, the number of the used wafers can be reduced, and the preparation process can be further reduced, so that the processing time and the cost can be reduced; in yet another aspect, the first conductive plug 18 is located above the bottom electrode 17, and the second conductive plug 20 is located above the top electrode 14, and is no longer led out through the substrate 10, so that no conductive hole is required to be formed on the substrate 10, the process difficulty is reduced, and the reliability of the filter obtained by processing is improved.

With continued reference to fig. 1, in a filter, to ensure isolation between different resonant structures of the filter, after the bottom electrode 17 is formed, it is required to etch the bottom electrode and then deposit the piezoelectric layer 16 thereon, which results in the formation of the piezoelectric layer 16 over the etched interface of the bottom electrode 17, thereby causing steps in the piezoelectric layer 16 grown in the height direction at the interface, discontinuity and certain deformation of the crystal lattice, so that the quality factor of the filter is low, and a larger stress concentration is easily generated at the etched interface, especially at high power, and the breakage of the film layer is easily caused.

In order to solve the foregoing problem, please continue to refer to fig. 2, in a specific embodiment, the upper and lower surfaces of the piezoelectric layer 16 of the filter provided by the embodiment of the application are both planar.

In order to realize that the upper and lower surfaces of the piezoelectric layer 16 are both planar, it is necessary to etch the bottom electrode 17 after forming the piezoelectric layer 16, and for this purpose, the piezoelectric layer 16 having both planar upper and lower surfaces can be obtained by providing the support substrate 22 (shown in fig. 5), by first forming the top electrode layer 24, the piezoelectric material layer 25, and the bottom electrode 17 in this order on the support substrate 22, and then removing the support substrate 22.

The piezoelectric layer 16 has a planar structure, namely, the upper surface and the lower surface are both planar, so that the quality of the piezoelectric layer 16 can be ensured, the quality factor of the filter is improved, meanwhile, the stress concentration of a film layer of the piezoelectric layer 16 can be avoided, the improvement of the reliability of the device is ensured, and the possibility of film layer fracture is reduced especially in a high-power use scene.

To facilitate formation of the top electrode 14 and to protect the top electrode 14, please continue with reference to fig. 2, in one embodiment, the resonant structure may further include:

a top electrode protection layer 15 disposed above the top electrode 14;

the first conductive plug 18 is electrically connected to the bottom electrode 17 through at least one of the top electrode protection layer 15, the top electrode 14, and the piezoelectric layer 16, and the second conductive plug 20 is electrically connected to the top electrode 14 through the top electrode protection layer 15.

Specifically, as shown in the figure, the first conductive plug 18 passes through only the top electrode protection layer 15, the top electrode 14, and the piezoelectric layer 16 of the piezoelectric layers 16, that is, in order to facilitate connection of the first conductive plug 18, the top electrode protection layer 15 may be provided with a top protection isolation groove (not shown by a reference numeral in the figure) corresponding to the top isolation groove 141, so that the first conductive plug 18 passes through the top protection isolation groove, the top isolation groove 141, and the conductive via 161 of the piezoelectric layer 16 to be electrically connected with the bottom electrode 17; in order to facilitate connection of the second conductive plug 20, the top electrode protection layer 15 may further be provided with a top conductive connection groove 151, and the second conductive plug 20 is electrically connected to the top electrode 14 through the top conductive connection groove 151.

Specifically, the material of the top electrode protection layer 15 may be aluminum oxide, silicon oxide, or the like.

The top electrode protection layer 15 can protect the top electrode 14 during the formation of the top electrode 14 and during the subsequent use, and can also play a role in repairing frequencies during the use of the filter.

In another embodiment, in order to protect the bottom electrode 17 and implement frequency trimming, as shown in fig. 2, the resonant structure of the filter provided by the embodiment of the present application may further include:

a bottom electrode protection layer 28 disposed below the bottom electrode 17.

Specifically, the bottom electrode protection layer 28 may be further provided with a bottom protection isolation groove (not shown in the figure) corresponding to the bottom isolation groove 171, under the influence of the processing procedure.

The material of the bottom electrode protection layer 28 may be alumina, silicon oxide, silicon nitride, or the like, and may be the same as or different from that of the top electrode protection layer 15.

In one embodiment, to facilitate the electrical connection between the first conductive plug 18 and the substrate 21, as shown in fig. 2, the first conductive plug 18 includes:

a first conductive support column 181 electrically connected to the bottom electrode 17 through the top electrode 14 and the piezoelectric layer 16;

The first package solder balls 182 are electrically connected to the first conductive support columns 181 and electrically connected to the substrate 21.

Of course, when the top isolation groove 141 and the conductive via 161 are opened, the first conductive support column 181 is electrically connected to the bottom electrode 17 through the top isolation groove 141 and the conductive via 161.

The first package solder balls 182 may be electrically connected to the first conductive support columns 181 and the substrate 21 by soldering.

The first conductive support column 181 may also serve as a support between the substrate 21 and the resonant structure of the filter to form the second cavity 30, and the material may be a metal having a conductive effect, such as gold, aluminum, magnesium, tungsten, copper, titanium, etc., or a mixture of metals or alloys having a conductive effect and a mixture of organic materials.

The first package solder balls 182 may facilitate soldering of the substrate 21 and the first conductive pillars 181, and the main material may be tin, silver, copper, gold, a mixture of aluminum metals or an alloy and a mixture of organic materials.

In order to facilitate soldering, in this embodiment, a material such as solder paste 33 may be further coated at soldering positions of the substrate 21 corresponding to the first package solder balls 182.

Of course, to facilitate the electrical connection of the second conductive plug 20 with the substrate 21, the second conductive plug 20 may include:

A second conductive support pillar 201 electrically connected to the top electrode 14;

and second package solder balls 202 electrically connected to the second conductive support columns 201 and electrically connected to the substrate 21.

The second conductive support pillars 201 may serve as a support between the substrate and the resonant structure of the filter, and the second cavity 30 may be formed of a conductive metal, such as gold, aluminum, magnesium, tungsten, copper, titanium, etc., which may be the same as or different from the first conductive support pillars 181.

The second package solder balls 202 may facilitate soldering of the substrate 21 and the second conductive support pillars 201, and the main material may be tin, silver, copper, a mixture of gold and aluminum metals or an alloy and a mixture of organic materials, which may be the same as or different from the first package solder balls 182.

In another embodiment, a material such as solder paste 33 may be applied to the substrate 21 at the bonding location corresponding to the second package solder ball 202 for convenience of bonding.

In order to prevent the molding compound from entering the second cavity 30 through the gap between the substrate 21 and the resonant structure during the molding process, in a specific embodiment, please continue to refer to fig. 3, the filter provided in the embodiment of the present application may further include:

And a protective film 12 that covers the substrate 10 and covers the substrate 21 that does not correspond to the substrate 10, and is hermetically connected to the substrate 21.

It is to be readily understood that "the substrate 21 not corresponding to the substrate 10" described herein refers to the portion a shown in fig. 3; the sealing connection with the substrate 21 means that the sealing connection with the substrate 21 is performed around the substrate 21.

In this way, the protective film 12 is disposed around the resonance structure of the filter and also covers the substrate 21 that does not correspond to the substrate 10, so that the possibility of preventing the molding compound from entering the inside of the filter and preventing intrusion of moisture and the like can be improved, and the reliability of the filter can be improved.

Specifically, the protective film 12 may be an organic film, the main material of which is an organic film composed of polyimide, epoxy resin, or the like.

Of course, the package and protection of the filter are realized by plastic packaging with the plastic packaging glue 13 at the outer side of the protection film 12. The material of the plastic packaging glue can be epoxy resin, polyimide and the like.

In order to solve the foregoing problems, an embodiment of the present invention further provides a method for forming a filter, so as to form the filter provided in any one of the foregoing embodiments. For convenience of understanding, a method of forming the filter will be described with reference to the accompanying drawings.

Referring to fig. 5 to 15, fig. 5 to 15 are schematic structural diagrams of steps of a method for forming a filter according to an embodiment of the invention.

As shown in fig. 15, a resonance structure is formed, the resonance structure includes a substrate 10, a bottom electrode 17, a piezoelectric layer 16, and a top electrode 14, the substrate 10 includes a cavity portion, the bottom electrode 17 is disposed above the cavity portion, a first cavity 19 is formed between the bottom electrode 17 and the cavity portion, the piezoelectric layer 16 is disposed above the bottom electrode 17, and the top electrode 14 is disposed above the piezoelectric layer 16.

The resonant structure is the basic structure of the filter, and after the resonant structure is formed, the subsequent processing of the filter is further performed.

As described above, since the filter includes at least one resonant structure, each resonant structure is formed simultaneously during the formation of the filter, in order to achieve isolation between different resonant structures, in this embodiment, the top electrode 14 of the resonant structure is provided with the top isolation groove 141 (shown in fig. 11), and the bottom electrode 17 is also provided with the bottom isolation groove 171 (shown in fig. 7), and for convenience of description, the scheme of providing the top isolation groove 141 and the bottom isolation groove 171 will be described in detail below.

It is to be understood that there are many methods for forming the resonant structure, and in one embodiment, referring to fig. 5-11, the steps for forming the resonant structure may include:

as shown in fig. 5, a support substrate 22 is provided;

the support substrate 22 is used to provide a process platform for subsequent processing. In this embodiment, the upper surface of the supporting substrate 22 is a plane, so that subsequent processing is facilitated.

In this embodiment, the material of the support substrate 22 is silicon. In other embodiments, the material of the support substrate 22 may be germanium, silicon carbide, gallium arsenide, indium gallium arsenide, or other materials, and the support substrate 22 may be silicon-on-insulator (SOI) or other types of substrates such as germanium-on-insulator. The material of the support substrate 22 may be a material suitable for process requirements or easy integration.

In one embodiment, as shown in fig. 6, a top electrode protection material layer 23, a top electrode layer 24, a piezoelectric material layer 25, the bottom electrode layer 26, and a bottom electrode protection material layer 27 are sequentially formed on the support substrate 22.

Specifically, the foregoing respective structural layers are formed by performing material deposition on the support substrate 22 through a deposition process.

It should be noted that, in the specific embodiment in which the grooves or the through holes are to be formed, the top electrode protection material layer 23, the top electrode layer 24, the piezoelectric material layer 25, the bottom electrode layer 26, and the bottom electrode protection material layer 27 are not structural layers before being formed, and the top electrode protection layer 15, the top electrode 14, the piezoelectric layer 16, the bottom electrode 17, and the bottom electrode protection layer 28 are respectively formed correspondingly with the grooves or the through holes; in embodiments where no corresponding recesses or vias are required, the top electrode protection layer 15, top electrode 14, piezoelectric layer 16, bottom electrode 17, and bottom electrode protection layer 28 are formed directly.

The thicknesses of the top electrode protective material layer 23, the top electrode layer 24, the piezoelectric material layer 25, the bottom electrode layer 26, and the bottom electrode protective material layer 27 may be set as needed, and are not limited herein.

The material selection of the top electrode protection material layer 23 and the bottom electrode protection material layer 27 may refer to the material descriptions of the top electrode protection layer 15 and the bottom electrode protection layer 28, the material selection of the top electrode layer 24 and the bottom electrode layer 26 may refer to the material descriptions of the top electrode 14 and the bottom electrode 17, and the material selection of the piezoelectric material layer 25 may refer to the material descriptions of the piezoelectric layer 16, which will not be repeated here.

As shown in fig. 7, a part of the bottom electrode protection material layer 27 is removed, and a bottom protection isolation groove (not shown by a reference numeral in the figure) is formed on the bottom electrode protection material layer 27, resulting in a bottom electrode protection layer 28;

and removing part of the bottom electrode layer 26, and forming a bottom isolation groove 171 on the bottom electrode layer 26 to obtain the bottom electrode 17.

The bottom electrode protection material layer 27 and the bottom electrode protection layer 28 are provided to protect the bottom electrode 17 from etching damage to the bottom electrode 17 when the bottom electrode 17 is formed.

After the bottom electrode 17 is formed, the bottom electrode protection layer 28 is reserved, and the frequency trimming effect can be realized in the working process of the filter.

Of course, in other embodiments, the bottom isolation groove 171 may be formed in other ways, such as: the position of the bottom isolation groove 171 may be directly etched without forming the bottom electrode protection layer 28; the bottom electrode protection layer 28 may be further removed after the isolation groove 171 is formed.

As shown in fig. 8, an insulating support layer 11 is formed on the bottom electrode protection layer 28 and the piezoelectric material layer 25, and the insulating support layer 11 is provided with a support cavity 111;

the support cavity 111 provides space for the subsequent formation of the first cavity 19.

It is to be readily understood that there may be various forming positions of the insulating support layer 11 depending on the circumstances:

1. In the present embodiment, the insulating support layer 11 may be formed on the piezoelectric material layer 25 and the bottom electrode protection layer 28 (shown in fig. 8) based on the structure of a specific filter on the basis of the opening of the bottom protection isolation groove and the bottom isolation groove 171.

2. In other embodiments, the insulating support layer 11 is formed only on the piezoelectric material layer 25 on the basis of the bottom protective isolation groove and the bottom isolation groove 171 being opened.

3. In other embodiments, the bottom electrode protection layer 28 may be formed only on the basis of the bottom protection isolation groove and the bottom isolation groove 171.

4. When the bottom electrode protective material layer 27 is deposited, if the bottom protective isolation groove and the bottom isolation groove 171 are not opened, the insulating support layer 11 may be directly formed on the bottom electrode protective material layer 27;

5. in the absence of the bottom electrode protection layer 28, if the bottom isolation groove 171 is not opened, the insulating support layer 11 may also be directly formed on the bottom electrode 17;

6. in the absence of the bottom electrode protection layer 28, if the bottom isolation groove 171 is opened, the insulating support layer 11 may also be formed only on the piezoelectric material layer 25;

7. in the absence of the bottom electrode protection layer 28, if the bottom isolation groove 171 is opened, the insulating support layer 11 may be formed only on the bottom electrode 17;

8. In the absence of the bottom electrode protection layer 28, if the bottom isolation groove 171 is provided, the insulating support layer 11 may also be formed on the piezoelectric material layer 25 and the bottom electrode 17.

Of course, when other structural layers are present, the position of specifically forming the insulating support layer 11 may be adjusted as needed.

The material of the insulating support layer 11 may be an insulating material such as monocrystalline silicon, polycrystalline silicon, silicon oxide, silicon nitride, gallium arsenide, sapphire, quartz, silicon carbide, or SOI.

The arrangement of the insulating support layer 11 ensures that the bottom electrode 17 is not in contact with the substrate 10, but in contact with the insulating support layer 11, different resonance structures of the filter can be better electrically isolated, the performance cannot be influenced due to the change of the substrate 10 under the high temperature condition, and therefore, the high temperature stability of the filter can be improved, and the performance of the filter is improved.

Further, in the embodiment of the present application, the insulating support layer 11 is formed on the piezoelectric material layer 25, so that the space can be more fully utilized and the insulating effect can be better achieved.

After the insulating support layer 11 is formed, further subsequent processing is performed.

As shown in fig. 9, the substrate 10 is provided and bonded so that the first cavity 19 is formed between the bottom electrode 17 and the cavity portion of the substrate 10.

The substrate is first provided and then the substrate 10 is bonded to the insulating support layer 11, so that the first cavity 19 is formed between the bottom electrode 17 and the cavity portion of the substrate 10.

It is to be understood that, based on the difference of the forming positions of the insulating and supporting layer 11, the forming structures of the first cavities 19 are also different, and the following forming modes are respectively adopted for the first cavities 19 according to the foregoing respective aspects:

1. the cavity portions of the insulating support layer 11, the piezoelectric material layer 25, the bottom electrode 17, the bottom electrode protection layer 28 and the substrate 10 form a first cavity 19 or the cavity portions of the insulating support layer 11, the bottom electrode protection layer 28 and the substrate 10 form a first cavity 19 corresponding to the formation position scheme 1 of the insulating support layer 11;

2. the cavity portions of the insulating support layer 11, the piezoelectric material layer 25, the bottom electrode 17, the bottom electrode protection layer 28 and the substrate 10 form a first cavity 19 or the cavity portions of the insulating support layer 11, the bottom electrode protection layer 28 and the substrate 10 form a first cavity 19 corresponding to the formation position scheme 2 of the insulating support layer 11;

3. the insulating support layer 11, the bottom electrode protection layer 28, and the cavity portion of the substrate 10 form a first cavity 19 corresponding to the formation position scheme 3 of the insulating support layer 11;

4. The insulating support layer 11, the bottom electrode protecting material layer 27, and the cavity portion of the substrate 10 form a first cavity 19 corresponding to the formation position scheme 4 of the foregoing insulating support layer 11;

5. the insulating support layer 11, the bottom electrode 17 and the cavity portion of the substrate 10 form a first cavity 19 corresponding to the formation position scheme 5 of the insulating support layer 11;

6. the insulating support layer 11, the piezoelectric material layer 25, the bottom electrode 17 and the cavity portion of the substrate 10 form a first cavity 19 or the insulating support layer 11, the bottom electrode 17 and the cavity portion of the substrate 10 form a first cavity 19 corresponding to the formation position scheme 6 of the insulating support layer 11;

7. the insulating support layer 11, the bottom electrode 17 and the cavity portion of the substrate 10 form a first cavity 19 corresponding to the formation position scheme 7 of the insulating support layer 11;

8. the cavity portions of the insulating support layer 11, the piezoelectric material layer 25, the bottom electrode 17 and the substrate 10 form a first cavity 19 or the cavity portions of the insulating support layer 11, the bottom electrode 17 and the substrate 10 form a first cavity 19 corresponding to the above-described formation position scheme 8 of the insulating support layer 11.

It will be appreciated that the structural layers surrounding the first cavity 19 may vary depending on the structural layer, such as in other embodiments, other structural layers may be present, but in either way the first cavity 19 is formed between the bottom electrode 17 and the cavity portion.

Of course, in other embodiments, the first cavity 19 may be formed not by a support cavity provided by the insulating support layer 11 but by a substrate cavity opened by the substrate, in which case the bottom wall of the substrate cavity is a cavity portion.

Note that, as in the foregoing description, the structural layers specifically bonded may also be different based on the difference between the bond and the structural layer formed before, and may specifically include:

A. the side walls of the substrate cavity may be bonded to the piezoelectric material layer 25 and the bottom electrode protection layer 28 on the basis of the bottom protection isolation groove and the bottom isolation groove 171.

B. The sidewalls of the substrate cavity may be bonded to the piezoelectric material layer 25 on the basis of the bottom protective isolation groove and the bottom isolation groove 171.

C. The sidewalls of the substrate cavity may be bonded to the bottom electrode protection layer 28 on the basis of the bottom protection isolation trench and the bottom isolation trench 171.

D. If the bottom electrode protection material layer 27 is deposited without the bottom protection isolation groove and the bottom isolation groove 171, the sidewall of the substrate cavity may be bonded to the bottom electrode protection material layer 27;

E. in the absence of the bottom electrode protection layer 28, if the bottom isolation groove 171 is not opened, the side wall of the substrate cavity can be bonded to the bottom electrode 17;

F. In the absence of the bottom electrode protection layer 28, if the bottom isolation groove 171 is provided, the side wall of the substrate cavity may also be bonded to the piezoelectric material layer 25;

G. in the absence of the bottom electrode protection layer 28, if the bottom isolation groove 171 is opened, the side wall of the substrate cavity may be bonded to the bottom electrode 17;

H. in the absence of the bottom electrode protection layer 28, the sidewalls of the substrate cavity may also be bonded to the piezoelectric material layer 25 and the bottom electrode 17 if the bottom isolation trench 171 is provided.

Based on the difference of the bonded structural layers, the structural layers forming the first cavity may also be different, and in particular, reference may be made to the description of the scheme for forming the insulating support layer 11, and only the insulating support layer 11 needs to be replaced by the side wall of the substrate cavity, which is not described herein again.

As shown in fig. 10, the support substrate 22 is removed.

The support substrate 22 provides a process platform for forming each layer of structure, and after the formation of each layer of structure is completed, the layer of structure is removed, and then the upper and lower positions are reversed, so that the substrate 10 is used as a support platform, and the subsequent processing is continued.

As shown in fig. 11, a part of the top electrode protection material layer 23 is removed, and a top conductive connection groove 151 and a top protection isolation groove (not shown by reference numerals in the figure) are formed on the top electrode protection material layer 23, resulting in a top electrode protection layer 15;

Removing a part of the top electrode layer 24, and forming the top isolation groove 141 on the top electrode layer 24 to obtain the top electrode 14, wherein the top protection isolation groove corresponds to the top isolation groove 141;

the piezoelectric material layer 25 is provided with the conductive via 161, and the piezoelectric layer 16 is formed.

It can be seen that the piezoelectric layer 16 obtained through the above steps has a planar structure, that is, the upper surface and the lower surface are both planar, so that the quality of the piezoelectric layer 16 can be ensured, and the quality factor of the filter can be improved, and meanwhile, the stress concentration of the piezoelectric layer 16 can be avoided, the improvement of the reliability of the device is ensured, and the possibility of breakage of the film layer is reduced especially in a high-power use situation.

Of course, it is easily understood that in other embodiments, the top electrode protection layer 15 may not be formed, and then the top electrode protection material layer 23 is not required to be formed in the foregoing step, and the top electrode protection material layer 23 is not required to be processed in this step.

As shown in fig. 12, a first conductive plug 18 and a second conductive plug 20 are formed on the resonant structure, the first conductive plug 18 is located above the bottom electrode 17 and electrically connected to the bottom electrode 17, and the second conductive plug 20 is located above the top electrode 14 and electrically connected to the top electrode 14.

Specifically, in this embodiment, the first conductive plug 18 is electrically connected to the bottom electrode 17 through the top protective isolation groove, the top isolation groove 141, and the conductive via 161, and the second conductive plug 20 is electrically connected to the top electrode 14 through the top conductive connection groove 151.

In one embodiment, the step of forming the first conductive plug 18 on the resonant structure may include:

forming a first conductive support column 181, the first conductive support column 181 being electrically connected to the bottom electrode 17;

and welding the first package solder balls 182 and the first conductive support columns 181 to obtain the first conductive plugs.

The first conductive support column 181 may be formed to serve as a support between the substrate 21 and the resonant structure of the filter to form the second cavity 30, and the first package solder ball 182 may be electrically connected to the first conductive support column 181 and the substrate 21 by soldering, so as to facilitate electrical connection with the substrate 21.

And the step of forming the second conductive plug 20 on the resonant structure may include:

forming a second conductive support column 201, the second conductive support column 201 being electrically connected to the top electrode 14;

and welding a second package solder ball 202 and the second conductive support pillar 201 to obtain the second conductive plug 20.

The second conductive support pillars 201 may also serve as a support between the substrate 21 and the resonant structure of the filter to form the second cavity 30, and the second package solder balls 202 may be disposed to electrically connect the second conductive support pillars 201 and the substrate 21 by soldering, so as to facilitate electrical connection with the substrate 21.

In another embodiment, to facilitate the electrical connection between the bottom electrode 17 and the first conductive plug 18, before the step of forming the first conductive plug 18 on the resonant structure, the method may further include:

forming a first re-wiring layer 31 on the bottom electrode, the first re-wiring layer 31 electrically connecting the bottom electrode 17;

the step of forming the first conductive plug 18 on the resonant structure may further comprise:

the first conductive plugs 18 are formed on the first rewiring layer 31, and the first conductive plugs 18 are electrically connected to the first rewiring layer 31.

In another embodiment, to facilitate the electrical connection between the second conductive plug 20 and the top electrode 14, the step of forming the second conductive plug on the resonant structure may further include:

As shown in fig. 13, a substrate 21 is provided.

For convenience of soldering, in the present embodiment, a material such as solder paste 33 may be coated at a soldering position of the substrate 21 corresponding to the first package solder ball 182 and at a soldering position of the substrate 21 corresponding to the second package solder ball 202.

As shown in fig. 14, a substrate is electrically connected to the first conductive plug 18 and the second conductive plug 20 such that the substrate forms a second cavity 30 with the first conductive plug 18, the second conductive plug 20, and the upper surface of the resonant structure.

The substrate 21 is electrically connected to the first conductive plug 18 and the second conductive plug 20, thereby forming a second cavity 30, resulting in a main structure of the filter.

When the first conductive plugs 18 include the first conductive support columns 181 and the first package solder balls 182, the first package solder balls 182 and the substrate 21 are soldered, electrically connecting the substrate 21 and the first conductive plugs 18.

When the second conductive plug 20 includes the second conductive support pillar 201 and the second package solder ball 202, the second package solder ball 202 and the substrate 21 are soldered, and the substrate 21 and the second conductive plug 20 are electrically connected.

As can be seen, in the method for forming a filter according to the embodiment of the present application, on one hand, when the substrate 21 is connected with the top electrode 14 and the bottom electrode 17, the substrate 21 is used to form the second cavity 30, so that the cover wafer is not required to be used to package the resonant structure of the filter, the use of the wafer is reduced, the thickness of the filter can be reduced, and the volume of the filter is reduced; on the other hand, the number of the used wafers can be reduced, and the preparation process can be further reduced, so that the processing time and the cost can be reduced; in yet another aspect, the first conductive plug 18 is located above the bottom electrode 17, and the second conductive plug 20 is located above the top electrode 14, and is no longer led out through the substrate 10, so that no conductive hole is required to be formed on the substrate 10, the process difficulty is reduced, and the reliability of the filter obtained by processing is improved.

As shown in fig. 15, the protective film 12 is formed on the substrate 10 and the substrate 21 such that the protective film 12 covers the substrate 10, covers the substrate 21 which does not correspond to the substrate 10, and is hermetically connected to the substrate 21.

As shown in fig. 2, a molding compound 13 is formed on the protective film 12.

The outside of the protective film 12 is subjected to plastic packaging by using plastic packaging glue 13, so that the packaging and the protection of the filter are realized.

In addition, the application also provides communication equipment comprising the filter in the previous embodiment.

The application also provides a terminal comprising a filter as described in the previous embodiments.

The foregoing describes several embodiments of the present application, and the various alternatives presented by the various embodiments may be combined, cross-referenced, with each other without conflict, extending beyond what is possible embodiments, all of which are considered to be embodiments of the present application disclosed and disclosed.

Although the embodiments of the present application are disclosed above, the present application is not limited thereto. Various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the application, and the scope of the application should be assessed accordingly to that of the appended claims.

Claims

1. A filter, comprising:

2. The filter of claim 1, wherein the upper and lower surfaces of the piezoelectric layer are planar.

3. The filter of claim 1, wherein the substrate defines a substrate cavity, a bottom wall of the substrate cavity is the cavity portion, the bottom electrode is disposed above the substrate, and the bottom electrode and the substrate form the first cavity.

4. The filter of claim 1, wherein the substrate defines a substrate cavity, the bottom wall of the substrate cavity defines the cavity portion, the bottom electrode defines a bottom isolation slot, at least a portion of the sidewall of the substrate cavity extends through the bottom isolation slot to support the piezoelectric layer, and at least the bottom electrode and the substrate define the first cavity.

5. The filter of claim 1, wherein the resonant structure further comprises:

6. The filter of claim 1, wherein the resonant structure further comprises:

7. The filter of claim 1, wherein the resonant structure further comprises:

the top electrode protection layer is arranged above the top electrode;

8. The filter of claim 1, wherein the resonant structure further comprises:

9. The filter of claim 1, wherein the first conductive plug comprises:

10. The filter of claim 1, wherein the second conductive plug comprises:

a second conductive support post electrically connected to the top electrode;

11. The filter of any of claims 1-10, further comprising:

12. The filter of any of claims 1-10, further comprising:

13. The filter of any of claims 1-10, further comprising:

14. A method of forming a filter, comprising:

15. The method of forming a filter of claim 14, wherein the step of forming a resonant structure comprises:

providing a support substrate;

removing the support substrate;

and removing part of the top electrode layer, forming a top isolation groove on the top electrode layer to obtain the top electrode, and forming a conductive through hole on the piezoelectric material layer to form the piezoelectric layer.

16. The method of forming a filter of claim 15, wherein the step of providing the substrate and bonding comprises:

17. The method of forming a filter of claim 15, wherein the bottom electrode is provided with a bottom isolation trench, and the step of providing the substrate and bonding comprises:

18. The method of forming a filter of claim 15, wherein the step of providing the substrate and bonding further comprises, prior to:

the step of providing the substrate and bonding includes:

providing the substrate;

19. The method of forming a filter of claim 15, wherein the bottom electrode is provided with a bottom isolation trench, and the step of providing the substrate and bonding further comprises, prior to:

the step of providing the substrate and bonding includes:

providing the substrate;

20. The method of forming a filter of claim 15, wherein the step of sequentially forming a top electrode layer, a piezoelectric material layer, and the bottom electrode on the support substrate further comprises:

forming a top electrode protection material layer on the support substrate;

21. The method of forming a filter of claim 15, wherein the step of sequentially forming a top electrode layer, a piezoelectric material layer, and the bottom electrode on the support substrate comprises:

22. The method of forming a filter of claim 14, wherein the step of forming a first conductive plug on the resonant structure comprises:

23. The method of forming a filter of claim 14, wherein the step of forming a second conductive plug on the resonant structure comprises:

24. The method of forming a filter of any of claims 14-23, further comprising:

25. The method of forming a filter of any of claims 14-23, further comprising, prior to the step of forming a first conductive plug on the resonant structure:

26. The method of forming a filter of any of claims 14-23, further comprising, prior to the step of forming a second conductive plug on the resonant structure:

27. A communication device comprising a filter according to any of claims 1-13.

28. A terminal comprising a filter according to any of claims 1-13.