CN115589212A - Bulk acoustic wave resonator with thin film package, manufacturing method and filter - Google Patents

Bulk acoustic wave resonator with thin film package, manufacturing method and filter Download PDF

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Publication number
CN115589212A
CN115589212A CN202211588810.4A CN202211588810A CN115589212A CN 115589212 A CN115589212 A CN 115589212A CN 202211588810 A CN202211588810 A CN 202211588810A CN 115589212 A CN115589212 A CN 115589212A
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acoustic wave
layer
bulk acoustic
thin film
wave resonator
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CN115589212B (en
Inventor
雷强
董元旦
杨涛
许夏茜
赵孟娟
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Chengdu Pinnacle Microwave Co Ltd
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Chengdu Pinnacle Microwave 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
    • H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
    • H03H9/17—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator
    • H03H9/171—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator implemented with thin-film techniques, i.e. of the film bulk acoustic resonator [FBAR] 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
    • 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
    • H03H9/10—Mounting in enclosures
    • H03H9/1007—Mounting in enclosures for bulk acoustic wave [BAW] devices
    • H03H9/1042—Mounting in enclosures for bulk acoustic wave [BAW] devices the enclosure being defined by a housing formed by a cavity in a resin
    • 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
    • H03H9/131—Driving means, e.g. electrodes, coils for networks consisting of piezoelectric or electrostrictive materials consisting of a multilayered structure
    • 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
    • H03H9/17—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator
    • H03H9/171—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator implemented with thin-film techniques, i.e. of the film bulk acoustic resonator [FBAR] type
    • H03H9/172—Means for mounting on a substrate, i.e. means constituting the material interface confining the waves to a volume
    • H03H9/175—Acoustic mirrors
    • 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
    • H03H2003/025—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 comprising an acoustic mirror
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

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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

The application discloses a bulk acoustic wave resonator with a thin film package, a manufacturing method and a filter, and solves the technical problem that the bulk acoustic wave resonator in the prior art is high in cost. The bulk acoustic wave resonator with thin film package of the present application includes: a substrate; a first acoustic mirror; a bottom electrode; a piezoelectric layer; a top electrode; a second acoustic mirror; packaging the film layer; a sealing layer; the first acoustic mirror, the bottom electrode, the piezoelectric layer, the top electrode, the second acoustic mirror, the packaging film layer and the sealing layer are sequentially stacked on the substrate; the sealing layer is used for sealing the bulk acoustic wave resonator. The scheme of this application realizes the independent encapsulation of bulk acoustic wave syntonizer, guarantees that the bulk acoustic wave syntonizer does not receive external disturbance, the cost is reduced.

Description

Bulk acoustic wave resonator with thin film package, manufacturing method and filter
Technical Field
The application relates to the technical field of electronic communication, in particular to a bulk acoustic wave resonator with a thin film package, a manufacturing method and a filter.
Background
The bulk acoustic wave resonator has the advantages of high working frequency, high quality factor, small volume, good roll-off effect and the like, and the corresponding bulk acoustic wave filter has the advantages of low insertion loss, high rectangular coefficient, high power capacity and the like. Therefore, such miniaturized and high-performance bulk acoustic wave filters and multiplexers are widely used in the rf front end of wireless communication systems, and play a great role in the field of wireless communication rf.
Because the inclined plane exists after the etching of the bottom electrode at the edge of the effective area of the bulk acoustic wave resonator, the crystal orientation of the piezoelectric film is inclined, and a transverse parasitic mode is generated. The acoustic waves of the lateral parasitic modes leak into the substrate at the boundaries of the resonator active area, showing a reduced quality factor in the electrical performance of the resonator as a parallel impedance or parallel resonance frequency.
In the prior art, in order to suppress leakage of a lateral parasitic mode acoustic wave of a resonator at an edge, a bump structure or a suspension wing structure is generally arranged at the edge of a top electrode of the resonator to form an acoustic impedance mismatch structure, so that the acoustic wave of the lateral mode is reflected and limited in an effective area of the resonator, and a quality factor of a parallel resonant frequency of the resonator is improved. However, these methods generate additional photolithography masks, which results in increased costs. Meanwhile, in order to improve reliability of the existing bulk acoustic wave filter, extra cap wafers are adopted for wafer level packaging, so that the bulk acoustic wave filter is prevented from being interfered by the external environment. The wafer level package not only increases the thickness of the bulk acoustic wave filter, resulting in increased volume, but also adds additional cost.
Disclosure of Invention
In order to solve at least one problem of the prior art, at least one embodiment of the present application provides a bulk acoustic wave resonator having a thin film package, a method of manufacturing the same, and a filter.
In a first aspect, an embodiment of the present invention provides a bulk acoustic wave resonator with a thin film package, including:
a substrate;
a first acoustic mirror;
a bottom electrode;
a piezoelectric layer;
a top electrode;
a second acoustic mirror;
packaging the film layer;
a sealing layer;
the first acoustic mirror, the bottom electrode, the piezoelectric layer, the top electrode, the second acoustic mirror, the packaging film layer and the sealing layer are sequentially stacked on the substrate;
the sealing layer is used for sealing the bulk acoustic wave resonator.
Preferably, the first acoustic mirror is located on the substrate or embedded inside the substrate
The first acoustic mirror includes a first body, first and second edge portions on both sides of the first body, a first edge outer side portion outside the first edge portion, and a second edge outer side portion outside the second edge portion;
the bottom electrode is positioned on the first acoustic mirror and comprises a first end and a second end, and the first end and the second end extend to the substrate;
the piezoelectric layer is arranged on the bottom electrode and is fully contacted with the bottom electrode and the substrate;
the top electrode is disposed above the piezoelectric layer and aligned with the first body of the first acoustic mirror;
the second acoustic mirror including set up in second main part on the top electrode, the second acoustic mirror still including set up in third marginal part and fourth marginal part on the piezoelectric layer, three marginal parts with fourth marginal part respectively with first marginal part and second edge part align.
Preferably, the lengths of the first edge portion, the second edge portion, the first edge outer side portion and the second edge outer side portion are all odd multiples of a quarter of the wavelength of the laterally propagating acoustic wave.
Preferably, the first acoustic mirror further comprises a first end and a second end,
wherein the first and second ends are located outboard of the first and second edge outer sides, respectively;
the bottom electrode, the piezoelectric layer and the sealing layer are sequentially stacked on the first end and the second end.
Preferably, the length of the first end and the second end is an odd multiple of one quarter of the wavelength of the laterally propagating acoustic wave.
Preferably, the material of the encapsulation film layer comprises one of aluminum nitride, aluminum oxide, polyimide, epoxy resin and ethyl silicate.
Preferably, the material of the sealing layer is one of silicon nitride and silicon oxide.
On the other hand, the present application also provides a method for manufacturing a bulk acoustic wave resonator, which is used for manufacturing the bulk acoustic wave resonator with the thin film package, and the method includes:
etching on the substrate to obtain a first cavity;
providing a first acoustic mirror on the substrate;
depositing a bottom electrode on the substrate and the first acoustic mirror, and patterning;
depositing a piezoelectric layer on the bottom electrode and patterning;
disposing a second acoustic mirror on the piezoelectric layer and the top electrode;
growing an encapsulation film layer on the second acoustic mirror and the piezoelectric layer;
and growing a sealing layer on the packaging thin film layer.
Preferably, the step of disposing a second acoustic mirror on the piezoelectric layer and the top electrode includes:
depositing a sacrificial layer on the piezoelectric layer and the top electrode;
patterning the sacrificial layer according to the shape of the second acoustic mirror;
and releasing the sacrificial layer to obtain the second acoustic mirror.
In another aspect, the present application also provides a bulk acoustic wave filter including the bulk acoustic wave resonator with the thin film package.
The embodiment of the invention has the advantages that: according to the bulk acoustic wave resonator with the thin film package, due to the arrangement of the sealing layer and the packaging thin film layer, the sealing layer is used for sealing the bulk acoustic wave resonator, so that the bulk acoustic wave resonator can be independently packaged under the condition that extra cap wafers are not used for wafer level packaging, the bulk acoustic wave resonator is prevented from being interfered by the outside, and the cost is reduced; furthermore, the sealing layer and the packaging film layer do not need additional photoetching masks, so that the cost is reduced; and the volume of the filter or the multiplexer composed of the bulk acoustic wave resonators can be reduced by encapsulating the filter or the multiplexer with the encapsulating film layer and the encapsulating layer.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art according to the drawings.
Fig. 1 is a schematic diagram of a bulk acoustic wave resonator with a thin film package according to an embodiment of the present application;
fig. 2 is a schematic diagram of another bulk acoustic wave resonator with a thin film package according to an embodiment of the present application;
fig. 3 is a smith chart of a bulk acoustic wave resonator with a thin film package according to an embodiment of the present application;
fig. 4 is a schematic impedance curve diagram of a bulk acoustic wave resonator according to an embodiment of the present application;
fig. 5 is a schematic diagram of another bulk acoustic wave resonator with a thin film package according to an embodiment of the present application;
fig. 6 is a schematic flowchart of a method for manufacturing a bulk acoustic wave resonator according to an embodiment of the present application.
Reference numerals:
the structure comprises a substrate 1, a first acoustic mirror 2, a bottom electrode 3, a piezoelectric layer 4, a top electrode 5, a second acoustic mirror 6, a packaging film layer 7 and a sealing layer 8;
a first body 21, a first edge 22a, a second edge 22b, a first edge outer 23a, and a second edge outer 23b;
a second body 61, a third edge 62, a fourth edge 63;
a first end 24a, a second end 24b.
Detailed Description
In order that the above objects, features and advantages of the present application can be more clearly understood, the present disclosure will be further described in detail with reference to the accompanying drawings and examples. It is to be understood that the embodiments described are only a few embodiments of the present disclosure, and not all embodiments. The specific embodiments described herein are merely illustrative of the disclosure and are not limiting of the application. All other embodiments that can be derived by one of ordinary skill in the art from the description of the embodiments are intended to be within the scope of the present disclosure.
It is noted that, in this document, relational terms such as "first" and "second," and the like, may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions.
Example 1
Because the inclined plane exists after the etching of the bottom electrode at the edge of the effective area of the bulk acoustic wave resonator, the crystal orientation of the piezoelectric film is inclined, and a transverse parasitic mode can be generated. These lateral modes of acoustic waves leak into the substrate at the resonator active area boundaries and appear as a decrease in the parallel impedance (Rp) or quality factor (Qp) of the parallel resonant frequency in the electrical performance of the resonator.
In the prior art, in order to suppress leakage of a lateral mode acoustic wave of a resonator at an edge, a bump structure or a suspension wing structure is generally arranged at the edge of a top electrode of the resonator to form an acoustic impedance mismatch structure, so that the lateral mode acoustic wave is reflected and limited in an effective area of the resonator, and a quality factor of a parallel resonant frequency of the resonator is improved. However, these methods generate additional photolithography masks, which results in increased costs. Meanwhile, in order to improve reliability of the existing bulk acoustic wave filter, an extra Cap Wafer (Cap Wafer) is adopted for Wafer level packaging, so that the bulk acoustic wave filter is not interfered by an external environment. The wafer level packaging method not only increases the thickness of the bulk acoustic wave filter, resulting in an increase in volume, but also adds additional cost.
In view of this, referring to fig. 1, in a first aspect, an embodiment of the present invention provides a bulk acoustic wave resonator with a thin film package, including:
a substrate 1;
a first acoustic mirror 2;
a bottom electrode 3;
a piezoelectric layer 4;
a top electrode 5;
a second acoustic mirror 6;
an encapsulating film layer 7;
a sealing layer 8;
the first acoustic mirror 2, the bottom electrode 3, the piezoelectric layer 4, the top electrode 5, the second acoustic mirror 6, the packaging film layer and the sealing layer 8 are sequentially stacked on the substrate 1; the sealing layer 8 is used for sealing the bulk acoustic wave resonator.
The material of the piezoelectric layer can be aluminum nitride (AlN), doped aluminum nitride (doped AlN), zinc oxide (ZnO), lead zirconate titanate (PZT), lithium niobate (LiNbO 3), quartz (Quartz), or lithium tantalate (LiTaO 3), etc., wherein the doped aluminum nitride contains at least one rare earth element, such as scandium (Sc), magnesium (Mg), ytterbium (Yb), etc.;
the materials of the substrate 1 include, but are not limited to: silicon (Si), gallium arsenide (GaAs), sapphire, quartz, etc.;
the material of the encapsulation thin film layer 7 may be aluminum nitride (AlN), aluminum oxide (Al 2O 3), and polymers, including but not limited to polyimide, epoxy resin, ethyl silicate.
The material of the sealing layer 8 may be silicon nitride (SiN), silicon oxide (SiOx), or the like.
Due to the arrangement of the sealing layer 8 and the packaging film layer 7, the sealing layer 8 is used for sealing the bulk acoustic wave resonator, so that the bulk acoustic wave resonator can be independently packaged under the condition that extra cap wafers are not used for wafer-level packaging, the bulk acoustic wave resonator is prevented from being interfered by the outside, and the cost is reduced; furthermore, an additional photoetching mask is not needed for the sealing layer 8 and the packaging film layer 7, so that the cost is reduced; further, the volume of the filter or the multiplexer including the bulk acoustic wave resonator can be reduced by sealing the sealing layer 8 and the sealing film layer 7.
Example 2
In the prior art, in order to suppress leakage of a lateral mode acoustic wave of a resonator at an edge, a raised structure or a suspension wing structure is generally arranged at the edge of a top electrode 5 of the resonator to form an acoustic impedance mismatched structure, the acoustic wave of the lateral mode is reflected and limited in an effective area of the resonator, and a quality factor of a parallel resonant frequency of the resonator is improved, but the modes generate additional photoetching masks, so that the cost is increased;
in view of this, referring to fig. 2, in the present embodiment, the first acoustic mirror 2 is located on the substrate 1 or embedded inside the substrate 1;
the first acoustic mirror 2 includes a first body 21, a first edge portion 22a and a second edge portion 22b located on both sides of the first body 21, a first edge outer portion 23a located outside the first edge portion 22a, and a second edge outer portion 23b located outside the second edge portion 22 b;
the bottom electrode 3 is located on the first acoustic mirror 2, the bottom electrode 3 comprises a first end and a second end, and the first end and the second end extend to the substrate 1;
the piezoelectric layer 4 is arranged on the bottom electrode 3 and is fully contacted with the bottom electrode 3 and the substrate 1;
the top electrode 5 is arranged above the piezoelectric layer 4 and aligned with the first body 21 of the first acoustic mirror 2;
the second acoustic mirror 6 comprises a second body 61 arranged on the top electrode 5, the second acoustic mirror 6 further comprises a third edge 62 and a fourth edge 63 arranged on the piezoelectric layer 4, the third edge and the fourth edge being aligned with the first edge 22a and the second edge 22b, respectively;
in this embodiment, the bulk acoustic wave resonator having a thin film package may be divided into a first region, a second region, and a third region, the first region includes the substrate 1, the main body of the first acoustic mirror 2, the bottom electrode 3, the piezoelectric layer 4, the top electrode 5, the main body of the second acoustic mirror 6, the package thin film layer 7, and the sealing layer 8 that are sequentially stacked in the thickness direction, the second region includes the substrate 1, the first edge portion 22a and the second edge portion 22b of the first acoustic mirror 2, the piezoelectric layer 4, the second acoustic mirror 6, the package thin film layer 7, and the sealing layer 8 that are sequentially stacked, and the third region includes the substrate 1, the first edge outer side portion 23a and the second edge outer side portion 23b of the first acoustic mirror 2, the bottom electrode 3, the piezoelectric layer 4, the package thin film layer 7, and the sealing layer 8 that are sequentially stacked;
it can be seen that the first region, the second region and the third region have different lamination states, so that acoustic impedances in the first region, the second region and the third region are mismatched, thereby forming an acoustic impedance mismatched interface, the transverse sound waves are reflected back to the effective excitation region (i.e. the first region) at the acoustic impedance mismatched interface, the parasitic mode of the resonator is reduced, the transverse sound waves are effectively inhibited from leaking into the substrate 1, and the quality factors of the parallel impedance and the parallel resonant frequency are improved; further, compared with the method that the protruding structure or the suspension wing structure is arranged at the edge of the top electrode of the resonator to form the acoustic impedance mismatching structure, the scheme of the embodiment only enables the different lamination states of the first area, the second area and the third area to be different through the packaging thin film layer 7 and the sealing layer 8, so that an acoustic impedance mismatching interface is formed, the packaging thin film layer 7 and the sealing layer 8 are arranged without a photoetching mask, and the manufacturing cost of the bulk acoustic wave resonator is reduced under the condition that the acoustic impedance mismatching structure is realized;
a conventional bulk acoustic wave resonator includes a substrate, a first acoustic mirror, a bottom electrode, a piezoelectric layer, a top electrode, and a second acoustic mirror, which are stacked in this order in the thickness direction, and is lacking an encapsulation thin film layer and a sealing layer as compared with the bulk acoustic wave resonator with a thin film encapsulation in example 2, which is taken as comparative example 1;
referring to fig. 3, a smith chart of the conventional bulk acoustic wave resonator and the bulk acoustic wave resonator with the packaged film in comparative example 1 and example 2, which is a calculated graph plotted on a reflection system dispersion plane with a normalized input impedance (or admittance) iso-circle family, shows that the loss is smaller the closer the curve is to the edge of the circle, and compared to the bulk acoustic wave resonator (comparative example 1), the bulk acoustic wave resonator with the film package (example 2) is below the series resonance frequency fs (lower left corner of smith circle), the intensity of the parasitic resonance mode is significantly reduced; above the series resonance frequency fs (semicircle on the smith circle), especially around the parallel resonance frequency fp, the curve is located closer to the circular edge. The transverse acoustic impedance mismatch structure can effectively limit transverse acoustic waves in an effective area of the resonator, reduce parasitic modes and improve the quality factor of parallel resonance frequency.
Referring to fig. 4, impedance graphs of the conventional bulk acoustic wave resonator and the bulk acoustic wave resonator with the encapsulation film in comparative example 1 and example 2, it can be seen that the resonator with the lateral acoustic impedance mismatch structure and the conventional resonator have the same size of the impedance portion other than the resonance frequency (fs or less and fp or more) in the case where the film structure thickness and the laminated structure are the same. The difference between the two is mainly concentrated above the series resonance frequency fs, particularly near the parallel resonance frequency fp, the impedance of the resonator with the transverse acoustic impedance mismatch structure is improved from 2810 omega to 3817 omega, and the quality factor (Qp) of the parallel resonance point is effectively improved.
Example 3
Based on the solution of embodiment 2, this embodiment further improves it, in this embodiment, the lengths of the first edge portion 22a, the second edge portion 22b, the first edge outer side portion 23a and the second edge outer side portion 23b are all odd multiples of a quarter of the wavelength of the laterally propagating acoustic wave, that is, the lengths of the second region and the third region are odd multiples of a quarter of the wavelength of the laterally propagating acoustic wave;
in order to realize sufficient mismatching of acoustic impedances, the transverse sound waves are effectively inhibited from leaking into the substrate 1, odd times of 1/4 transverse propagation sound wave wavelength are selected for the widths of the second region and the third region of the impedance mismatching region, the lengths of the second region and the third region are limited, the material cost can be saved, and the area of the resonator is reduced; the transverse sound wave can be more effectively limited in the effective area of the resonator, parasitic modes are reduced, and the quality factor (Qp) of the parallel resonance frequency is improved.
Example 4
This embodiment further improves the embodiment 2, as shown in fig. 5, the first acoustic mirror 2 further includes a first end 24a and a second end 24b,
wherein the first and second ends 24a, 24b are located outboard of the first and second edge outer portions 23a, 23b, respectively;
the bottom electrode 3, the piezoelectric layer 4, and the sealing layer 8 are sequentially stacked on the first end 24a and the second end 24b.
In this embodiment, the bulk acoustic wave resonator with the thin film package may further divide a fourth region according to the first end and the second end, where the fourth region is located outside the third region, where the fourth region includes the substrate 1, the first acoustic mirror 2, the bottom electrode 3, the piezoelectric layer 4, and the sealing layer 8, which are sequentially stacked;
it can be seen that the second region, the third region and the fourth region have different lamination states, so that acoustic impedances of the second region, the third region and the fourth region are different, and transverse sound waves are reflected for multiple times in the second region, the third region and the fourth region, so that sound wave energy can be more effectively limited in an effective resonance region (namely the first region) of the resonator, a parasitic mode is further weakened, and a quality factor of a parallel resonance frequency is improved.
Example 5
On the basis of embodiment 3, this embodiment further improves the acoustic wave propagation structure, wherein the lengths of the first end and the second end are odd multiples of a quarter of the wavelength of the laterally propagating acoustic wave, that is, the length of the fourth region is odd multiples of a quarter of the wavelength of the laterally propagating acoustic wave;
in order to realize sufficient mismatch of acoustic impedance and effectively inhibit transverse sound waves from leaking into the substrate 1, the width of the fourth region with mismatched impedance is selected to be 1/4 odd times of the wavelength of the transverse propagation sound waves, the length of the fourth region is limited, the material cost can be saved, and the area of a resonator is reduced; the transverse sound wave can be more effectively limited in the effective area of the resonator, parasitic modes are reduced, and the quality factor of the parallel resonance frequency is improved.
Example 6
Referring to fig. 6, the present embodiment further provides a method for manufacturing a bulk acoustic wave resonator, which is used for manufacturing the bulk acoustic wave resonator with the thin film package, and the method includes:
s1: providing a first acoustic mirror on the substrate;
s2: depositing a bottom electrode on the substrate and the first acoustic mirror and patterning;
s3: depositing a piezoelectric layer on the bottom electrode and patterning;
s4: disposing a second acoustic mirror on the piezoelectric layer and the top electrode;
s5: growing an encapsulation membrane layer over the second acoustic mirror and the piezoelectric layer;
s6: and growing a sealing layer on the packaging thin film layer.
Preferably, the step of providing a first acoustic mirror on the substrate includes:
depositing a sacrificial layer on the piezoelectric layer and the top electrode;
patterning the sacrificial layer according to the shape of the second acoustic mirror;
releasing the sacrificial layer to obtain the second acoustic mirror;
in this and preferred embodiments, first a first acoustic mirror is provided on the substrate, which may be a cavity structure embedded in the substrate or any other acoustic mirror structure, such as a bragg reflector; depositing a bottom electrode on the first acoustic mirror and the substrate, and patterning the bottom electrode, wherein the bottom electrode is located on the first acoustic mirror and extends to the substrate; subsequently depositing a piezoelectric layer on the substrate and the bottom electrode and patterning the piezoelectric layer so that the piezoelectric layer is in full contact with the substrate and the bottom electrode; depositing a top electrode on the piezoelectric layer and patterning; subsequently disposing a second acoustic mirror on the top electrode and the piezoelectric layer, the second acoustic mirror completely covering the top electrode, the second acoustic mirror may be a cavity structure, and the cavity structure may be formed by depositing a sacrificial layer on the piezoelectric layer and the top electrode and patterning the sacrificial layer to obtain a sacrificial layer in the shape of the cavity structure; then growing a packaging film layer on the second acoustic mirror and the piezoelectric layer, patterning the packaging film layer to obtain a sacrificial layer release hole, and releasing the sacrificial layer through the sacrificial layer release hole to obtain a first acoustic mirror and a second acoustic mirror; finally, growing a sealing layer on the packaging film layer to obtain the bulk acoustic wave resonator with the film package;
due to the arrangement of the sealing layer and the packaging film layer, the sealing layer is used for sealing the bulk acoustic wave resonator, so that the bulk acoustic wave resonator can be independently packaged without using an additional cap wafer for wafer-level packaging, the bulk acoustic wave resonator is prevented from being interfered by the outside, and the cost is reduced; furthermore, an additional photoetching mask is not needed for the sealing layer and the packaging film layer, so that the cost is reduced; and the volume of the bulk acoustic wave resonator can be reduced by packaging the sealing layer and the packaging thin film layer.
Example 7
The embodiment also provides a bulk acoustic wave filter which comprises the bulk acoustic wave resonator with the thin film package.
In order to improve reliability of the existing bulk acoustic wave filter, extra cap wafers are adopted for wafer level packaging, so that the bulk acoustic wave filter is not interfered by the external environment, but the thickness of the bulk acoustic wave filter is increased by the packaging mode, so that the size is increased, extra cost is increased, the bulk acoustic wave filter comprising the bulk acoustic wave resonator with the thin film package is realized due to the arrangement of the sealing layer and the packaging thin film layer in the bulk acoustic wave resonator with the thin film package, the bulk acoustic wave resonator is independently packaged, the extra cap wafers are not required for wafer level packaging, and the manufacturing cost of the bulk acoustic wave filter is reduced.
In another embodiment of the present application, there is also provided a multiplexer including the bulk acoustic wave resonator with a thin film package.
It should be noted that the bulk acoustic wave filter in this embodiment includes the bulk acoustic wave resonator with the thin film package in the foregoing embodiment, and therefore, for the specific implementation and the achieved technical effect of this embodiment, reference may be made to the implementation of the bulk acoustic wave resonator with the thin film package, and details are not repeated here.
It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrases "comprising a component of' 8230; \8230;" does not exclude the presence of another like element in a process, method, article, or apparatus that comprises the element.
It will be understood by those skilled in the art that although some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the application and form different embodiments.
Those skilled in the art will appreciate that the description of each embodiment has a respective emphasis, and reference may be made to the related description of other embodiments for those parts of an embodiment that are not described in detail.
Although the embodiments of the present application have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present application, and such modifications and variations fall within the scope defined by the appended claims.

Claims (10)

1. A bulk acoustic wave resonator having a thin film package, comprising:
a substrate;
a first acoustic mirror;
a bottom electrode;
a piezoelectric layer;
a top electrode;
a second acoustic mirror;
packaging the film layer;
a sealing layer;
the first acoustic mirror, the bottom electrode, the piezoelectric layer, the top electrode, the second acoustic mirror, the packaging film layer and the sealing layer are sequentially stacked on the substrate;
the sealing layer is used for sealing the bulk acoustic wave resonator.
2. The bulk acoustic wave resonator with thin film encapsulation of claim 1, characterized in that the first acoustic mirror is located on or embedded inside the substrate;
the first acoustic mirror includes a first body, first and second edge portions on both sides of the first body, a first edge outer side portion outside the first edge portion, and a second edge outer side portion outside the second edge portion;
the bottom electrode is positioned on the first acoustic mirror and comprises a first end and a second end, and the first end and the second end extend to the substrate;
the piezoelectric layer is arranged on the bottom electrode and is fully contacted with the bottom electrode and the substrate;
the top electrode is disposed above the piezoelectric layer and aligned with the first body of the first acoustic mirror;
the second acoustic mirror including set up in second main part on the top electrode, the second acoustic mirror still including set up in third edge portion and fourth edge portion on the piezoelectric layer, third edge portion with fourth edge portion respectively with first edge portion and second edge portion align.
3. The bulk acoustic wave resonator with thin film encapsulation of claim 2, characterized in that the lengths of the first edge portion, the second edge portion, the first edge outer side portion and the second edge outer side portion are all odd multiples of a quarter of a wavelength of a laterally propagating acoustic wave.
4. The bulk acoustic wave resonator with thin film encapsulation of claim 2, wherein the first acoustic mirror further comprises a first end and a second end,
wherein the first and second ends are located outboard of the first and second edge outer sides, respectively;
the bottom electrode, the piezoelectric layer and the sealing layer are sequentially stacked on the first end and the second end.
5. The bulk acoustic wave resonator with thin film encapsulation of claim 4, characterized in that the length of the first end and the second end is an odd multiple of one quarter of the wavelength of a laterally propagating acoustic wave.
6. The bulk acoustic resonator with thin film encapsulation of claim 1, wherein the material of the encapsulation thin film layer comprises one of aluminum nitride, aluminum oxide, polyimide, epoxy, and ethyl silicate.
7. The bulk acoustic wave resonator having a thin film package according to claim 1, wherein a material of the sealing layer is one of silicon nitride and silicon oxide.
8. A method of manufacturing a bulk acoustic wave resonator for manufacturing a bulk acoustic wave resonator having a thin film package according to any one of claims 1 to 7, comprising:
providing a first acoustic mirror on the substrate;
depositing a bottom electrode on the substrate and the first acoustic mirror and patterning;
depositing a piezoelectric layer on the bottom electrode and patterning;
disposing a second acoustic mirror on the piezoelectric layer and the top electrode;
growing an encapsulation membrane layer over the second acoustic mirror and the piezoelectric layer;
and growing a sealing layer on the packaging thin film layer.
9. The method of manufacturing a bulk acoustic wave resonator according to claim 8, wherein the step of providing a second acoustic mirror on the piezoelectric layer and the top electrode comprises:
depositing a sacrificial layer on the piezoelectric layer and the top electrode;
patterning the sacrificial layer according to the shape of the second acoustic mirror;
and releasing the sacrificial layer to obtain the second acoustic mirror.
10. A bulk acoustic wave filter comprising the bulk acoustic wave resonator having a thin film package according to any one of claims 1 to 7.
CN202211588810.4A 2022-12-12 2022-12-12 Bulk acoustic wave resonator with thin film package, manufacturing method and filter Active CN115589212B (en)

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