CN117879535B - BAW filter and manufacturing method thereof - Google Patents

BAW filter and manufacturing method thereof Download PDF

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Publication number
CN117879535B
CN117879535B CN202410274435.9A CN202410274435A CN117879535B CN 117879535 B CN117879535 B CN 117879535B CN 202410274435 A CN202410274435 A CN 202410274435A CN 117879535 B CN117879535 B CN 117879535B
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Prior art keywords
layer
electrode layer
temperature compensation
upper electrode
baw filter
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CN202410274435.9A
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CN117879535A (en
Inventor
魏彬
邹洁
唐供宾
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Shenzhen Newsonic Technologies Co Ltd
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Shenzhen Newsonic Technologies Co Ltd
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/46—Filters
    • H03H9/54—Filters comprising resonators of piezoelectric or electrostrictive material
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
    • H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
    • H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
    • H03H3/04—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks for obtaining desired frequency or temperature coefficient
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/02007—Details of bulk acoustic wave devices
    • H03H9/02086—Means for compensation or elimination of undesirable effects
    • H03H9/02118—Means for compensation or elimination of undesirable effects of lateral leakage between adjacent resonators
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/05—Holders; Supports
    • H03H9/08—Holders with means for regulating temperature
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/125—Driving means, e.g. electrodes, coils
    • H03H9/13—Driving means, e.g. electrodes, coils for networks consisting of piezoelectric or electrostrictive materials
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
    • H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
    • H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
    • H03H2003/023—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks the resonators or networks being of the membrane type
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
    • H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
    • H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
    • H03H3/04—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks for obtaining desired frequency or temperature coefficient
    • H03H2003/0407—Temperature coefficient

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  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)

Abstract

It is an object of an embodiment of the application to provide a BAW filter and a method of manufacturing the same. The BAW filter comprises a substrate, a fence layer, a piezoelectric layer, an upper electrode layer, a lower electrode layer and a target structure; wherein the rail layer is disposed over the substrate; wherein the piezoelectric layer is disposed above the rail layer; wherein the upper electrode layer is disposed above the piezoelectric layer, and the lower electrode layer is disposed below the piezoelectric layer; wherein the target structure comprises at least any one of the following structures: a temperature compensation structure; an air ring structure; an air bridge structure. The embodiment of the application has the following advantages: by arranging at least any one of a temperature compensation structure, an air ring structure and an air bridge structure in the BAW filter, the influence of temperature change on the performance of the device is reduced, the transverse wave energy loss of the electrode surface is reduced, and the quality factor Q value of the BAW filter is improved.

Description

BAW filter and manufacturing method thereof
Technical Field
The present invention relates to the field of semiconductors, and in particular to BAW filters and methods of manufacturing the same.
Background
Currently, acoustic filters are largely classified into surface acoustic wave (Surface Acoustic Wave, SAW) filters and bulk acoustic wave (Bulk Acoustic Wave, BAW) filters. BAW filters are different from SAW filters in that acoustic waves in BAW are propagated longitudinally, i.e. in bulk acoustic wave resonators using quartz crystals as the substrate, metal sheets on the upper and lower surfaces of the quartz excite to form acoustic waves, which jump from the top surface to the bottom surface, forming standing waves. Therefore, resonator structures in BAW filters need to be completed on carrier substrates using thin film deposition and micromachining techniques.
However, in the BAW filter structure according to the prior art, the stress between the film layers varies with the temperature, which easily results in the performance of the device varying. And, the quality factor of BAW filters is to be improved due to the loss of transverse wave energy at the electrode surface.
Disclosure of Invention
It is an object of embodiments of the present application to provide a BAW filter and a method of manufacturing the same.
The embodiment of the application provides a BAW filter, which comprises a substrate, a fence layer, a piezoelectric layer, an upper electrode layer, a lower electrode layer and a target structure
Wherein the rail layer is disposed over the substrate;
Wherein the piezoelectric layer is disposed above the rail layer;
Wherein the upper electrode layer is disposed above the piezoelectric layer, and the lower electrode layer is disposed below the piezoelectric layer;
Wherein the target structure comprises at least any one of the following structures:
A temperature compensation structure;
An air ring structure;
An air bridge structure.
According to one embodiment, the temperature compensating structure is a temperature compensating layer, which is arranged between the upper electrode layer and the piezoelectric layer, or between the lower electrode layer and the piezoelectric layer.
According to one embodiment, the material of the temperature compensation layer is silicate glass (USG) or phosphate glass (PSG) or the like, and the thickness is 500A to 5000A.
According to one embodiment, the air ring structure is formed between the edge of the upper electrode layer and the piezoelectric layer.
According to one embodiment, the air bridge structure is arranged between the upper electrode layer and the piezoelectric layer.
An embodiment of the present application provides a method of manufacturing a BAW filter, the method comprising:
Forming a target structure in the process of manufacturing the BAW filter, wherein the target structure comprises at least any one of a temperature compensation structure, an air ring structure and an air bridge structure;
wherein the method further comprises:
forming an upper electrode layer over the temporary substrate;
forming a piezoelectric layer over the upper electrode layer;
Forming a lower electrode layer over the piezoelectric layer;
Etching the lower electrode layer;
Removing the temporary substrate and forming a fence layer over the substrate;
And etching the upper electrode layer.
An embodiment of the application provides an electronic device comprising a BAW filter according to an embodiment of the application, or an integrated circuit comprising a BAW filter according to an embodiment of the application.
Compared with the prior art, the embodiment of the application has the following advantages: according to the BAW filter and the manufacturing method thereof, the performance of the BAW filter is improved by arranging at least any one of the temperature compensation structure, the air ring structure and the air bridge structure in the BAW filter; by arranging the temperature compensation layer serving as a temperature compensation structure, the BAW filter is provided with a film with a negative temperature coefficient, so that the influence of temperature change on the performance of the device is reduced; by arranging the air ring structure and the air bridge structure, the transverse wave energy loss on the surface of the electrode is reduced, and the quality factor Q value of the BAW filter is improved.
Drawings
Other features, objects and advantages of the present invention will become more apparent upon reading of the detailed description of non-limiting embodiments, made with reference to the accompanying drawings in which:
Fig. 1 shows a schematic diagram of an exemplary BAW filter with a temperature compensation structure according to an embodiment of the present application;
FIG. 2 (a) shows a schematic diagram of a BAW filter provided with a temperature compensation layer and an air ring structure according to an embodiment of the present application;
fig. 2 (b) shows a schematic diagram of a BAW filter provided with a temperature compensation layer and an air bridge structure according to an embodiment of the present application;
Fig. 2 (c) shows a schematic diagram of a BAW filter provided with an air ring structure and an air bridge structure according to an embodiment of the present application;
Fig. 3 shows a schematic structural diagram of another exemplary BAW filter with a temperature compensation structure according to an embodiment of the present application;
fig. 4 shows a flow chart of a method of manufacturing a BAW filter in accordance with an embodiment of the present application;
Fig. 5 shows a flow chart of a method of manufacturing a BAW filter with a temperature compensation structure according to an embodiment of the present application;
fig. 6 shows a schematic diagram of an exemplary structure formed during the fabrication of a BAW filter with a temperature compensation structure in accordance with an embodiment of the present application;
fig. 7 shows a schematic diagram of an exemplary structure formed during the fabrication of a BAW filter with a temperature compensation structure in accordance with an embodiment of the present application;
fig. 8 shows a schematic diagram of an exemplary structure formed during the fabrication of a BAW filter with a temperature compensation structure in accordance with an embodiment of the present application;
Fig. 9 shows a schematic diagram of an exemplary structure formed during the fabrication of a BAW filter with a temperature compensation structure in accordance with an embodiment of the present application;
fig. 10 shows a schematic diagram of an exemplary structure formed during the fabrication of a BAW filter with a temperature compensation structure in accordance with an embodiment of the present application;
fig. 11 shows a schematic diagram of an exemplary structure formed during the fabrication of a BAW filter with a temperature compensation structure, in accordance with an embodiment of the present application.
The same or similar reference numbers in the drawings refer to the same or similar parts.
Detailed Description
Before discussing exemplary embodiments in more detail, it should be mentioned that some exemplary embodiments are described as processes or methods depicted as flowcharts. Although a flowchart depicts operations as a sequential process, many of the operations can be performed in parallel, concurrently, or at the same time. Furthermore, the order of the operations may be rearranged. The process may be terminated when its operations are completed, but may have additional steps not included in the figures. The processes may correspond to methods, functions, procedures, subroutines, and the like.
Specific structural and functional details disclosed herein are merely representative and are for purposes of describing exemplary embodiments of the application. The application may be embodied in many alternate forms and should not be construed as limited to only the embodiments set forth herein.
It will be understood that, although the terms "first," "second," etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of example embodiments. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
It should also be noted that, in some alternative implementations, the functions/acts noted may occur out of the order noted in the figures. For example, two figures shown in succession may in fact be executed substantially concurrently or the figures may sometimes be executed in the reverse order, depending upon the functionality/acts involved.
According to an embodiment of the application, a BAW filter with a temperature compensation structure comprises a substrate, a fence layer, a piezoelectric layer, an upper electrode layer, a lower electrode layer and a target structure.
Wherein the substrate is used for carrying a chip or other electronic device. Materials of the substrate include, but are not limited to, silicon (Si), silicon Carbide (Silicon Carbide), or aluminum oxide, etc.
Wherein the rail layer is disposed over the substrate. The fence layer forms a lower cavity through a release process after enclosing the filling layer. Optionally, the fence layer is a groove structure.
Optionally, the material of the fence layer may include silicon, silicon nitride, or a high temperature resistant organic material.
Wherein the piezoelectric layer is disposed above the rail layer.
The material of the piezoelectric layer may be various materials having piezoelectric characteristics. Alternatively, the material of the piezoelectric layer includes, but is not limited to, aluminum nitride (AlN), alN doped with rare earth elements such as scandium, erbium, lanthanum, etc., zinc oxide (ZnO), or lithium niobate (LiNbO 3).
Wherein the upper electrode layer is disposed above the piezoelectric layer, and the lower electrode layer is disposed below the piezoelectric layer.
Wherein, the fence layer, the piezoelectric layer and the lower electrode layer are provided with a cavity therebetween.
The materials of the upper electrode layer and the lower electrode layer may be various metal materials having conductive properties, or may be a combination of various metal materials having conductive properties. Alternatively, the materials of the upper and lower electrode layers include, but are not limited to, molybdenum (Mo), aluminum (Al), copper (Cu), platinum (Pt), tantalum (Ta), tungsten (W), and the like.
Wherein the target structure comprises at least any one of the following structures:
1) A temperature compensation structure;
optionally, the temperature compensation structure is a temperature compensation layer, the material of the temperature compensation layer is silicate glass (USG) or phosphate glass (PSG) or the like, and the thickness of the temperature compensation layer ranges from 500 angstroms (a) to 5000A;
optionally, the temperature compensation layer is disposed between the upper electrode layer and the piezoelectric layer, or the temperature compensation layer is disposed between the lower electrode layer and the piezoelectric layer;
2) An air ring structure; the air ring structure is used for reducing the transverse leakage of sound waves;
Optionally, the air ring structure is formed between an edge of the upper electrode layer and the piezoelectric layer;
3) An air bridge structure; the air bridge structure is used for reducing the transverse leakage of sound waves;
Optionally, the thickness of the air bridge structure is 500A to 5000A.
One skilled in the art may, based on actual requirements, choose a suitable one or a combination of structures from among the temperature compensation structure, the air ring structure and the air bridge structure to arrange in the BAW filter.
Wherein, if the BAW filter includes both the temperature compensation structure and the air ring structure, the temperature compensation structure and the air ring structure have the same thickness since the temperature compensation structure and the air ring structure are formed based on the same layer of film.
The BAW filter of the embodiment of the present application is described below with reference to the drawings.
According to one implementation, a BAW filter of an embodiment of the present application may include the temperature compensation structure, the air ring structure, and an air bridge structure. For example, fig. 1 shows a schematic diagram of a BAW filter provided with a temperature compensation layer, an air ring structure and an air bridge structure.
The BAW filter with the temperature compensation structure shown in fig. 1 includes an upper electrode layer 101, a temperature compensation layer 102, a piezoelectric layer 103, a lower electrode layer 104, a rail layer 105, a substrate 106, and an air bridge structure 107.
Wherein the fence layer 105 is disposed over the substrate 106, and the fence layer 105 is a groove structure.
Wherein the piezoelectric layer 103 is disposed above the rail layer 105.
Wherein a cavity is provided among the fence layer 105, the piezoelectric layer 103 and the lower electrode layer 104.
Wherein the upper electrode layer 101 is disposed above the piezoelectric layer 103, and the lower electrode layer 104 is disposed below the piezoelectric layer 103.
As shown in fig. 1, the right side edge of the piezoelectric layer 103 has two regions of different thicknesses, so that an air ring structure shown by a dashed frame is formed between the right side end of the upper electrode layer 101 and the piezoelectric layer 103. Wherein, the height of the air ring structure is consistent with the thickness of the temperature compensation layer 102. Wherein the air bridge structure 107 is arranged between the upper electrode layer 101 and the piezoelectric layer 103. The thickness of the air bridge structure 107 is the same as that of the thermal compensation layer 102.
According to one embodiment, the BAW filter may comprise any two of the temperature compensation structure, the air ring structure and the air bridge structure. Fig. 2 (a) to 2 (c) show schematic diagrams of BAW filters comprising any two combinations of temperature compensation structure, air ring structure and air bridge structure, respectively.
The upper electrode layer 201, the temperature compensation layer 202, the piezoelectric layer 203, the lower electrode layer 204, the rail layer 205, the substrate 206, and the air bridge structure 207 shown in fig. 2 (a) to 2 (c) are similar to the structures of the corresponding upper electrode layer 101, the temperature compensation layer 102, the piezoelectric layer 103, the lower electrode layer 104, the rail layer 105, the substrate 106, and the air bridge structure 107 in fig. 1.
Fig. 2 (a) shows a schematic diagram of a BAW filter provided with a temperature compensation layer 202 arranged between the upper electrode layer 201 and the piezoelectric layer 203, and an air ring structure as indicated by the dashed box.
Wherein, the height of the air ring structure is the same as the thickness of the temperature compensation layer 202.
Fig. 2 (b) shows a schematic diagram of a BAW filter provided with a temperature compensation layer 202 and an air bridge structure, the temperature compensation layer 202 and the air bridge structure 207 are each provided between the upper electrode layer 201 and the piezoelectric layer 203, and the thickness of the temperature compensation layer 202 and the air bridge structure 207 are the same.
Fig. 2 (c) shows a schematic diagram of a BAW filter provided with an air ring structure and an air bridge structure. Wherein, the air ring structure is shown as a dashed box, and the air bridge structure 207 is disposed between the upper electrode layer 201 and the piezoelectric layer 203.
According to one embodiment, the BAW filter may comprise any one of the temperature compensation structure, the air ring structure, and an air bridge structure.
For example, referring to the schematic structural diagram shown in fig. 1, only the temperature compensation layer 102 as a temperature compensation structure may be included in the BAW filter according to the present embodiment, and the air ring structure shown by the dotted line frame (i.e., the right edge of the upper electrode layer 101 is aligned with the piezoelectric layer 103 below it, as shown in fig. 2 (b)), and the air bridge structure 107 are not included. Similarly, the BAW filter according to the present embodiment may include only the air ring structure shown by the dotted frame, and does not include the temperature compensation layer 102 and the air bridge structure 107. Or only the air bridge structure 107 may be included in the BAW filter according to the present embodiment, without including the temperature compensation layer 102 and the air ring structure shown by the dotted line frame.
Alternatively, the temperature compensation layer in the BAW filter according to the present embodiment may be provided at other positions. For example, fig. 3 shows a schematic structural diagram of another exemplary BAW filter with a temperature compensation structure according to an embodiment of the present application.
Referring to fig. 3, the BAW filter with a temperature compensation structure is shown to include a substrate 306, a rail layer 305, a piezoelectric layer 303, an upper electrode layer 301, a lower electrode layer 304, and a temperature compensation layer 302.
The substrate 306, the enclosure layer 305, the piezoelectric layer 303, the upper electrode layer 301, and the lower electrode layer 304 are similar to the structures of the substrate 106, the enclosure layer 105, the piezoelectric layer 103, the upper electrode layer 101, and the lower electrode layer 104 in fig. 1, and will not be described herein.
Unlike the structure shown in fig. 1, a temperature compensation layer 302 of the BAW filter shown in fig. 3 is provided between a lower electrode layer 304 and a piezoelectric layer 303.
According to the BAW filter provided by the embodiment of the application, the performance of the BAW filter is improved by arranging at least any one of the temperature compensation structure, the air ring structure and the air bridge structure in the BAW filter; by arranging the temperature compensation layer serving as a temperature compensation structure, the BAW filter is provided with a film with a negative temperature coefficient, so that the influence of temperature change on the performance of the device is reduced; by arranging the air ring structure and the air bridge structure, the transverse wave energy loss on the surface of the electrode is reduced, and the quality factor Q value of the BAW filter is improved.
Fig. 4 shows a flow chart of a method of manufacturing a BAW filter according to an embodiment of the present application.
The method includes step S407, and steps S401 to S406 (not shown).
In step S407, a target structure including at least any one of a temperature compensation structure, an air ring structure, and an air bridge structure is formed in the process of manufacturing the BAW filter. The temperature compensation structure, the air ring structure and the air bridge structure are described in the foregoing, and are not described herein.
The following describes the steps S401 to S406.
In step S401, an electrode layer is formed over a temporary substrate.
Specifically, a temporary substrate is obtained, and an upper electrode layer is formed over the temporary substrate. Wherein the material of the temporary substrate comprises, but is not limited to, silicon (Si), silicon carbide (SiC), aluminum oxide or the like.
Wherein the uniformity of the upper electrode layer is less than 1%.
Optionally, the upper electrode layer is deposited on the temporary substrate by a chemical vapor deposition (chemical vapor deposition, CVD) process.
The material of the upper electrode layer may be various metal materials having conductive properties, or may be a combination of various metal materials having conductive properties. Alternatively, the materials of the upper and lower electrode layers include, but are not limited to, molybdenum (Mo), aluminum (Al), copper (Cu), platinum (Pt), tantalum (Ta), tungsten (W), or the like.
In step S402, a piezoelectric layer is formed over the upper electrode layer.
The material of the piezoelectric layer may be various materials having piezoelectric characteristics. Alternatively, the material of the piezoelectric layer includes, but is not limited to, aluminum nitride (AlN), alN doped with rare earth elements such as scandium, erbium, lanthanum, etc., zinc oxide (ZnO), lithium niobate (LiNbO 3), or the like.
Alternatively, the piezoelectric layer is deposited on the upper electrode layer by a chemical vapor deposition process.
In step S403, a lower electrode layer is formed over the piezoelectric layer.
The material of the lower electrode layer may be various metal materials having conductive properties, or may be a combination of various metal materials having conductive properties. Alternatively, the materials of the upper and lower electrode layers include, but are not limited to, molybdenum (Mo), aluminum (Al), copper (Cu), platinum (Pt), tantalum (Ta), tungsten (W), or the like.
Optionally, the uniformity of the upper electrode layer and the lower electrode layer is less than 1%.
Alternatively, the lower electrode layer is deposited on the piezoelectric layer by a chemical vapor deposition process.
In step S404, the lower electrode layer is subjected to etching treatment.
Wherein the etching process includes a patterned etching process.
Optionally, the etching process further includes a thickness etching process for reducing the thickness by photolithography, etching, or the like.
Wherein the method employs a variety of etching processes to perform the etching process, such as a plasma etching process, a wet etching process, or a combination of both.
Optionally, the etching uniformity of the lower electrode layer is less than 1%.
In step S405, the temporary substrate is removed and a fence layer is formed over the substrate.
Specifically, a substrate is obtained, and a fence layer is formed over the substrate. And then, turning the structure after the temporary substrate is removed up and down.
Wherein the step of forming the fence layer comprises: forming a filling layer in a gap between the lower electrode layer and the piezoelectric layer; the rail layer is formed by enclosing the filling layer.
Wherein the material of the filling layer comprises, but is not limited to, silicon dioxide doped with phosphorus or boron, silicon nitride and the like.
And then removing the filling layer through a release process to form a lower cavity among the fence layer, the lower electrode layer and the piezoelectric layer.
In step S406, the etching process is performed on the upper electrode layer. The etching process of the upper electrode layer is the same as or similar to the etching process in step S404, and will not be described here again.
Wherein the execution order of the step S407 and the steps S401 to S406 is determined based on the structure included in the target structure.
According to one embodiment, the target structure includes a temperature compensation layer as a temperature compensation structure, and the step S407 includes a step S4071 and a step S4072.
In step S4071, after the upper electrode layer is formed, a temperature compensation layer is formed over the upper electrode layer.
Optionally, the material of the temperature compensation layer is silicate glass (USG) or phosphate glass (PSG) and the like, and the thickness of the temperature compensation layer ranges from 500A to 5000A.
In step S4072, the temperature compensation layer is subjected to etching treatment.
Optionally, the etching angle required for etching the temperature compensation layer is 10 to 60 degrees.
Optionally, the damage to the substrate required to etch the temperature compensation layer is less than 100A.
Wherein, the steps S4071 and S4072 are performed after the step S401 and before the step S402.
According to one embodiment, the target structure comprises an air ring structure, and the step S407 comprises a step S4073 and a step S4074.
After the upper electrode layer is formed in step S4073, a filling structure for forming an air ring structure is formed at the edge of the upper electrode layer.
In step S4074, the filling structure is removed to form an air ring structure between the edge of the upper electrode layer and the piezoelectric layer.
Wherein the step S4073 is performed after the step S401 and before the step S402, and the step S4074 is performed after the step S406.
Alternatively, if a temperature compensating layer and an air ring structure are provided in the BAW filter, a filling structure may be formed using a material of the temperature compensating layer, and the temperature compensating layer and the air ring structure may be formed simultaneously. Wherein, the height of the air ring structure is the same as the thickness of the temperature compensation layer.
According to one embodiment, the target structure comprises an air bridge structure, and the step S407 comprises a step S4075 and a step S4076.
After the upper electrode layer is formed, a filling structure for constituting an air bridge structure is formed over the upper electrode layer in step S4075.
In step S4074, the filling structure is removed to form an air bridge structure between the upper electrode layer and the piezoelectric layer.
Alternatively, if the BAW filter comprises a temperature compensation layer and an air bridge structure, the thickness of the air bridge structure and the temperature compensation layer are the same.
Wherein the step S4073 is performed after the step S401 and before the step S402, and the step S4074 is performed after the step S406.
Alternatively, if a temperature compensating layer and an air bridge structure are provided in the BAW filter, a filling structure may be formed using a material of the temperature compensating layer, and the temperature compensating layer and the air bridge structure may be formed simultaneously. The thickness of the air bridge structure is the same as that of the temperature compensation layer.
A method of manufacturing a BAW filter according to an embodiment of the present application will be described with reference to fig. 5 to 11.
Fig. 5 shows a flow chart of a method of manufacturing a BAW filter with a temperature compensation structure according to an embodiment of the present application.
The method comprises steps S501 to S508. Wherein the method flowchart shown in fig. 5 corresponds to a manufacturing process of manufacturing the BAW filter having the temperature compensation structure as shown in fig. 2 (a).
Fig. 6 to 11 respectively show schematic diagrams of structures formed during manufacturing of a BAW filter having a temperature compensation structure according to an embodiment of the present application.
The respective reference numerals in fig. 6 to 11 and their corresponding components are represented as follows:
10: a temporary substrate;
11: an upper electrode layer;
12: a temperature compensation layer;
13: a piezoelectric layer;
14: a lower electrode layer;
15: a filling layer;
16: a rail layer;
17: a substrate.
Referring to fig. 5 and 6, in step S501, an upper electrode layer 11 is formed over a temporary substrate 10.
Specifically, a temporary substrate 10 is obtained, and an upper electrode layer 11 is formed over the temporary substrate 10.
Wherein the uniformity of the upper electrode layer 11 is less than 1%.
Optionally, the upper electrode layer 11 is deposited on the temporary substrate 10 by a chemical vapor deposition (chemical vapor deposition, CVD) process.
In step S502, a temperature compensation layer 12 is formed on the upper electrode layer 11.
The material of the thermal compensation layer 12 is silicate glass (USG) or phosphate glass (PSG), and the thickness of the thermal compensation layer 12 ranges from 500A to 5000A.
In step S503, the temperature compensation layer 12 is subjected to etching treatment. As shown in fig. 7, the etched thermal compensation layer 12 includes two parts, which are located in the middle region and the edge region of the upper electrode layer 11, respectively.
The etching angle required for etching the temperature compensation layer 12 is 10 to 60 degrees, and the damage to the substrate required for etching the temperature compensation layer 12 is less than 100A.
In step S504, the piezoelectric layer 13 is formed over the upper electrode layer 11 and the etched thermal compensation layer 12.
The material of the piezoelectric layer 13 has been described in the embodiment shown in fig. 4, and will not be described here again.
Alternatively, the piezoelectric layer 13 is deposited on the upper electrode layer 11 by a chemical vapor deposition process.
In step S505, a lower electrode layer 14 is formed over the piezoelectric layer 13. The lower electrode layer 14 is formed as shown in fig. 8.
The material of the lower electrode layer 14 is described in the embodiment shown in fig. 4, and will not be described herein.
Alternatively, the lower electrode layer 14 is deposited on the piezoelectric layer 13 by a chemical vapor deposition process.
In step S506, the lower electrode layer 14 is subjected to etching treatment.
The etching treatment comprises a graphical etching treatment and a thickness etching treatment. The pattern etching process and the thickness etching process are the same as the etching process in the step S404, and are not described herein. Wherein the etch uniformity of the lower electrode layer 14 is less than 1%. The lower electrode layer 14 obtained by the etching treatment is shown in fig. 9.
In step S507, the temporary substrate 10 is removed and the fence layer 16 is formed over the substrate 17.
Referring to fig. 9 and 10, a substrate 17 is obtained, and a fence layer 16 is formed over the substrate 17. Next, the structure shown in fig. 9 is inverted after the temporary substrate is removed, thereby forming the structure shown in fig. 9.
The method according to the present embodiment further includes step S509 and step S510 before step S507.
In step S509, the filler layer 15 is formed in the gap between the lower electrode layer 14 and the piezoelectric layer 13.
In step S508, the etching process is performed on the upper electrode layer 11.
Specifically, the etching process includes a patterned etching process and a thickness etching process. The upper electrode layer 11 obtained by the etching treatment is shown in fig. 9.
Wherein, the etching uniformity of the upper electrode layer 11 is less than 1%.
In step S510, the filling layer 15 is removed, and a cavity is formed between the rail layer 16, the lower electrode layer 14, and the piezoelectric layer 13.
Wherein the method further comprises step S511.
In step S511, a portion of the thermal compensation layer located at the edge region is removed to form an air ring structure between the edge of the upper electrode layer 11 and the piezoelectric layer 13.
Based on the structure shown in fig. 10, after the filling layer 15 is removed and a part of the temperature compensation layer located in the edge region is removed, the structure shown in fig. 11 is formed, and the structure shown in fig. 11 forms an air ring structure between the right edge of the upper electrode layer 11 and the piezoelectric layer 13.
Methods of manufacturing BAW filters according to other embodiments of the present application are described below.
The steps for manufacturing a BAW filter provided with a temperature compensation layer, an air ring structure and an air bridge structure as shown in fig. 1 are similar to those shown in fig. 5. In contrast, the step of forming the air bridge structure is added to the step described in fig. 5.
The steps for manufacturing a BAW filter provided with a temperature compensation layer and an air bridge structure as shown in fig. 2 (b) are similar to those shown in fig. 5. In contrast, the step of forming an air bridge is added after step S501 and the step of forming an air ring structure is removed on the basis of the step described in fig. 5. Wherein, can form warm benefit layer and air bridge structure in step, the thickness of air bridge structure is the same with the thickness of warm benefit layer.
The steps of manufacturing a BAW filter provided with an air ring structure and an air bridge structure as shown in fig. 2 (c) are similar to those shown in fig. 5. In contrast, the step of forming an air bridge is added after step S501 on the basis of the step described in fig. 5, and step 502 of forming a temperature compensation layer and step S503 of etching the temperature compensation layer are removed.
The steps for manufacturing a BAW filter provided with only a temperature compensation layer are similar to those shown in fig. 5. In contrast, if the position of the temperature compensating layer is the same as that of the temperature compensating layer shown in fig. 2 (a), the step of forming the air ring structure and the air bridge structure is removed on the basis of the step described in fig. 5; if the position of the temperature compensating layer is different from that of the temperature compensating layer shown in fig. 2 (a), for example, a step of manufacturing a BAW filter provided with the temperature compensating layer as shown in fig. 3, a step of forming a piezoelectric layer is performed first, and then a step of forming the temperature compensating layer and a step of etching the temperature compensating layer are performed on the basis of the step described in fig. 5, thereby obtaining a structure in which the temperature compensating layer shown in fig. 3 is provided between a lower electrode layer and the piezoelectric layer. Also, referring to fig. 3, in the step of etching the lower electrode layer, the left edge of the lower electrode layer 304 exceeds the left edge of the temperature compensation layer 302 by 0 to 10um.
The steps for manufacturing a BAW filter provided with only an air ring structure are similar to those shown in fig. 5. In contrast, the steps of forming the temperature compensation layer, etching the temperature compensation layer, and forming the air bridge structure are removed on the basis of the steps described in fig. 5.
The steps of manufacturing a BAW filter provided with only an air bridge structure are similar to those shown in fig. 5. In contrast, the steps of forming the temperature compensation layer, etching the temperature compensation layer, and forming the air ring structure are removed on the basis of the steps described in fig. 5.
According to the method for the BAW filter, provided by the embodiment of the application, the performance of the BAW filter is improved by arranging at least any one of a temperature compensation structure, an air ring structure and an air bridge structure in the BAW filter; by arranging the temperature compensation layer serving as a temperature compensation structure, the BAW filter is provided with a film with a negative temperature coefficient, so that the influence of temperature change on the performance of the device is reduced; by arranging the air ring structure and the air bridge structure, the transverse wave energy loss on the surface of the electrode is reduced, and the quality factor Q value of the BAW filter is improved.
Based on the foregoing embodiment of the present application, another embodiment of the present application further provides an electronic device, where the electronic device includes the BAW filter described in the foregoing embodiment, or the electronic device includes an integrated circuit, where the integrated circuit includes the BAW filter described in the foregoing embodiment.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present application, and are not limiting; although the application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present application.
Furthermore, it is evident that the word "comprising" does not exclude other elements or steps, and that the singular does not exclude a plurality. A plurality of units or devices in the embodiments of the present application may also be implemented by one unit or device in software or hardware. The terms first, second, etc. are used to denote a name, but not any particular order.

Claims (7)

1. A BAW filter comprising a substrate, a rail layer, a piezoelectric layer, an upper electrode layer, a lower electrode layer, and a target structure;
wherein the rail layer is disposed over the substrate;
Wherein the piezoelectric layer is disposed above the rail layer;
Wherein the upper electrode layer is disposed above the piezoelectric layer, and the lower electrode layer is disposed below the piezoelectric layer;
the target structure comprises a temperature compensation structure, an air ring structure and an air bridge structure, and the BAW filter is provided with a film with a negative temperature coefficient by arranging the temperature compensation structure;
The thickness of the temperature compensation structure is consistent with that of the air ring structure;
the temperature compensation structure is a temperature compensation layer, and the temperature compensation layer is arranged between the upper electrode layer and the piezoelectric layer;
Wherein the air ring structure is formed between an edge of the upper electrode layer and the piezoelectric layer, the air bridge structure being disposed between the upper electrode layer and the piezoelectric layer;
Wherein a cavity is arranged among the fence layer, the piezoelectric layer and the lower electrode layer;
Wherein, the orthographic projection of the air bridge structure on the substrate plane overlaps with orthographic projections of the fence layer and the cavity on the substrate plane.
2. The BAW filter of claim 1, wherein the temperature compensating layer is of silicate glass (USG) or phosphate glass (PSG) and has a thickness of 500A to 5000A.
3. A method of manufacturing a BAW filter, the method comprising:
Forming a target structure in the process of manufacturing the BAW filter, wherein the target structure comprises a temperature compensation structure, an air ring structure and an air bridge structure;
wherein the method further comprises:
forming an upper electrode layer over the temporary substrate;
forming a piezoelectric layer over the upper electrode layer;
Forming a lower electrode layer over the piezoelectric layer;
Etching the lower electrode layer;
Removing the temporary substrate and forming a fence layer over the substrate;
Etching the upper electrode layer;
The thickness of the temperature compensation structure is consistent with that of the air ring structure;
Wherein, the BAW filter has a film with negative temperature coefficient by setting a temperature compensation structure;
the temperature compensation structure is a temperature compensation layer, and the temperature compensation layer is arranged between the upper electrode layer and the piezoelectric layer;
Wherein the air ring structure is formed between an edge of the upper electrode layer and the piezoelectric layer, the air bridge structure being disposed between the upper electrode layer and the piezoelectric layer;
Wherein a cavity is arranged among the fence layer, the piezoelectric layer and the lower electrode layer;
Wherein, the orthographic projection of the air bridge structure on the substrate plane overlaps with orthographic projections of the fence layer and the cavity on the substrate plane.
4. A method according to claim 3, wherein forming the target structure during fabrication of the BAW filter comprises:
Forming a temperature compensation layer on the upper electrode layer after forming the upper electrode layer;
and etching the temperature compensation layer.
5. A method according to claim 3, wherein the target structure comprises an air ring structure, and wherein forming the target structure during manufacture of the BAW filter comprises:
after forming the upper electrode layer, forming a filling structure for forming an air ring structure at the edge of the upper electrode layer;
the filling structure is removed to form an air ring structure between the edge of the upper electrode layer and the piezoelectric layer.
6. A method according to claim 3, wherein the target structure comprises an air bridge structure, the forming the target structure during fabrication of the BAW filter comprising:
forming a filling structure for forming an air bridge structure on the upper electrode layer after forming the upper electrode layer;
The filling structure is removed to form an air bridge structure between the upper electrode layer and the piezoelectric layer.
7. An electronic device comprising the BAW filter of claim 1 or 2 or an integrated circuit comprising the BAW filter of claim 1 or 2.
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US20230030749A1 (en) * 2021-08-02 2023-02-02 Resonant Inc. Hybrid fenced substrate for transversely-excited film bulk acoustic resonator frontside membrane release
CN113872558A (en) * 2021-09-29 2021-12-31 苏州汉天下电子有限公司 Resonator manufacturing method and resonator
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CN109802646A (en) * 2018-12-26 2019-05-24 天津大学 Resonator, filter with temperature compensating layer
CN110868182A (en) * 2019-04-23 2020-03-06 中国电子科技集团公司第十三研究所 Resonator and filter
CN117559939A (en) * 2023-02-23 2024-02-13 北京芯溪半导体科技有限公司 Bulk acoustic wave resonator, forming method thereof and filter

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