CN111313859B - Bulk acoustic wave resonator, method of manufacturing the same, filter, and electronic apparatus - Google Patents
Bulk acoustic wave resonator, method of manufacturing the same, filter, and electronic apparatus Download PDFInfo
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- CN111313859B CN111313859B CN201911197893.2A CN201911197893A CN111313859B CN 111313859 B CN111313859 B CN 111313859B CN 201911197893 A CN201911197893 A CN 201911197893A CN 111313859 B CN111313859 B CN 111313859B
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Classifications
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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
- H03H9/02007—Details of bulk acoustic wave devices
-
- 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 piezo-electric 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
Abstract
The invention discloses a bulk acoustic wave resonator, comprising: a substrate; an acoustic mirror; a bottom electrode having a bottom electrode pin; a top electrode having a top electrode pin; a piezoelectric layer disposed between the bottom electrode and the top electrode, wherein: a first gap exists between a sandwich structure formed by the bottom electrode, the top electrode and the piezoelectric layer and the upper surface of the substrate, so that the main body resonance structure of the resonator is in non-contact with the substrate. The resonator may further include a protective structure layer having a first portion connected to the upper surface of the substrate and a second portion having an outer end connected to an inner end of the first portion, the second portion extending above the piezoelectric layer along the piezoelectric layer and at least a portion of the second portion forming a second gap with the piezoelectric layer in a thickness direction, and the second portion being spaced apart from the top electrode in a lateral direction. The invention also discloses a manufacturing method of the bulk acoustic wave resonator, a filter with the resonator and electronic equipment with the filter or the resonator.
Description
Technical Field
The present invention relates to the field of semiconductors, and more particularly, to a bulk acoustic wave resonator, a method of manufacturing the same, a filter, and an electronic apparatus having the resonator or the filter.
Background
As an essential element of electronic devices, electronic devices have been widely used, and their application range includes mobile phones, automobiles, home electric appliances, and the like. In addition, technologies such as artificial intelligence, internet of things, 5G communication and the like, which are about to change the world in the future, still need to rely on electronic devices as a basis.
Film bulk acoustic resonators (Film Bulk Acoustic Resonator, abbreviated as FBARs, also called BAWs) are playing an important role as important members of piezoelectric devices in the communication field, particularly FBAR filters have an increasing share of market in the field of radio frequency filters, and FBARs have excellent characteristics of small size, high resonant frequency, high quality factor, large power capacity, good roll-off effect and the like, and the filters are gradually replacing traditional Surface Acoustic Wave (SAW) filters and ceramic filters, playing a great role in the field of radio frequency for wireless communication, and the advantages of high sensitivity can be applied to sensing fields such as biology, physics, medicine and the like.
The structural main body of the film bulk acoustic resonator is a sandwich structure consisting of electrodes, piezoelectric films and electrodes, namely a layer of piezoelectric material is sandwiched between two metal electrode layers. By inputting a sinusoidal signal between the two electrodes, the FBAR converts an input electrical signal into mechanical resonance using an inverse piezoelectric effect, and converts the mechanical resonance into an electrical signal output using a piezoelectric effect.
A high frequency resonator with a high quality factor and low dynamic impedance is preferred for an integrated oscillator. In recent years, as the package size of the resonator is reduced, frequency drift of the resonator due to the influence of external stress is more serious, and the performance and stability of the resonator are seriously affected.
With the rapid development of integrated circuit technology, the frequency stability of FBAR resonators is increasingly important. In order to accommodate the trend of miniaturization, it is necessary to solve or alleviate the frequency stability problem of the FBAR resonator.
Disclosure of Invention
In order to alleviate or solve the above-mentioned problems in the prior art, the present invention proposes a bulk acoustic wave resonator whose frequency is not affected by external stress.
According to an aspect of an embodiment of the present invention, there is provided a bulk acoustic wave resonator including:
a substrate;
an acoustic mirror;
a bottom electrode having a bottom electrode pin;
a top electrode having a top electrode pin;
a piezoelectric layer disposed between the bottom electrode and the top electrode,
wherein:
a first gap exists between a sandwich structure formed by the bottom electrode, the top electrode and the piezoelectric layer and the upper surface of the substrate, and the first gap enables a main body resonance structure formed by the bottom electrode, the piezoelectric layer and the top electrode of the resonator to be in non-contact with the substrate.
Optionally, the resonator further includes a protective structure layer including a first portion connected to the upper surface of the substrate and a second portion connected at an outer end thereof to an inner end of the first portion, the second portion extending above the piezoelectric layer along the piezoelectric layer and at least a portion of the second portion forming a second gap in a thickness direction with the piezoelectric layer, and the second portion being spaced apart from the top electrode in a lateral direction.
The embodiment of the invention also relates to a manufacturing method of a bulk acoustic wave resonator, the bulk acoustic wave resonator comprises a substrate, an acoustic mirror, a bottom electrode, a piezoelectric layer and a top electrode, wherein the bottom electrode, the piezoelectric layer and the top electrode form a sandwich structure, and the method comprises the following steps:
(1) Forming a first sacrificial layer, wherein the first sacrificial layer is positioned between a sandwich structure which is formed or is to be formed and the upper surface of the substrate;
(2) Forming a second sacrificial layer which is connected with the first sacrificial layer, covers the piezoelectric layer and extends along the piezoelectric layer to cover a part of the upper surface of the piezoelectric layer;
(3) Forming a protective structure layer, wherein one part of the protective structure layer covers the upper surface of the substrate, the other part of the protective structure layer extends to cover the upper surface of the second sacrificial layer, and the position of the protective structure layer is separated from the top electrode in the transverse direction;
(4) And releasing the first sacrificial layer and the second sacrificial layer, wherein a first gap is formed after the first sacrificial layer is released, a second gap is formed after the second sacrificial layer is released, and the first gap is communicated with the second gap.
Optionally, the step (1) includes: forming a first sacrificial layer between the piezoelectric layer and the underside of the bottom electrode and the upper surface of the substrate; in the step (3), a protective structure layer and a top electrode are formed at the same time.
Optionally, in step (1), a first sacrificial layer is formed between the lower side of the sandwich structure formed by the top electrode, the piezoelectric layer and the bottom electrode and the upper surface of the substrate; in the step (2), the second sacrificial layer covers the sandwich structure from the upper side and is connected with the first sacrificial layer.
Optionally, in step (3), another portion of the protective structure layer is entirely located on the upper surface of the second sacrificial layer. Or alternatively, in step (3), another portion of the protective structure layer covers the upper surface of the second sacrificial layer and covers the upper surface of the piezoelectric layer.
The embodiment of the invention also relates to a filter comprising the bulk acoustic wave resonator.
Embodiments of the invention also relate to an electronic device comprising a filter as described above or a resonator as described above.
Drawings
These and other features and advantages of the various embodiments of the disclosed invention will be better understood from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate like parts throughout the several views, and wherein:
FIG. 1A is a schematic cross-sectional view (in the direction B-B of FIG. 1B or FIG. 1C) of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention;
FIG. 1B is a schematic top view of the bulk acoustic wave resonator of FIG. 1A in accordance with an exemplary embodiment of the invention;
FIG. 1C is a schematic top view of the bulk acoustic wave resonator of FIG. 1A in accordance with an exemplary embodiment of the invention;
FIG. 2A is a schematic cross-sectional view (in the direction B-B of FIG. 2B) of a bulk acoustic wave resonator according to an exemplary embodiment of the invention;
FIG. 2B is a schematic top view of the bulk acoustic wave resonator of FIG. 2A in accordance with an exemplary embodiment of the invention;
FIG. 2C is a schematic cross-sectional view (in the direction C-C of FIG. 2B) of a bulk acoustic wave resonator according to an exemplary embodiment of the invention;
FIG. 2D is a schematic cross-sectional view (in the direction D-D of FIG. 2B) of a bulk acoustic wave resonator according to an exemplary embodiment of the invention;
FIG. 3 is a schematic cross-sectional view of a bulk acoustic wave resonator (similar to the direction B-B along FIG. 1B or FIG. 1C) according to an exemplary embodiment of the present invention;
FIG. 4A is a schematic cross-sectional view (in the direction B-B of FIG. 4B) of a bulk acoustic wave resonator according to an exemplary embodiment of the invention;
FIG. 4B is a schematic top view of the bulk acoustic wave resonator of FIG. 4A in accordance with an exemplary embodiment of the invention;
fig. 5A-5F are schematic views of a fabrication process of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention;
fig. 6A to 6F are schematic views illustrating a manufacturing process of a bulk acoustic wave resonator according to another exemplary embodiment of the present invention.
Detailed Description
The technical scheme of the invention is further specifically described below through examples and with reference to the accompanying drawings. In the specification, the same or similar reference numerals denote the same or similar components. The following description of embodiments of the present invention with reference to the accompanying drawings is intended to illustrate the general inventive concept and should not be taken as limiting the invention.
Fig. 1A is a schematic cross-sectional view (in the direction B-B of fig. 1B or 1C) of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention. Fig. 1B is a schematic top view of the bulk acoustic wave resonator of fig. 1A in accordance with an exemplary embodiment of the invention. Fig. 1C is a schematic top view of the bulk acoustic wave resonator of fig. 1A in accordance with an exemplary embodiment of the invention.
In fig. 1A to 1C, reference numerals are denoted as follows:
101: substrates, e.g. silicon, etc
103: cavities, other acoustic mirror structures such as Bragg reflector layers
105: a bottom electrode, which is not in contact with the substrate 101 and has an air gap
107: a piezoelectric layer having an air gap between a portion of the piezoelectric layer located outside the bottom electrode (a portion within the main body resonance structure) and the substrate 101
109: top electrode
111: passivation layers, e.g. aluminum nitride (AlN), silicon nitride, etc
113: an air gap separating the bottom electrode 105 and the substrate 101, the piezoelectric layer 107 and the substrate 101, the protective structure 115 and the piezoelectric layer 107
115: the protection structure is composed of two parts: the portion connected to the substrate is a first portion 115a, and the suspended portion, which is not connected to the other layers, is a second portion 115b, which is a suspended structure. The end point of the second portion is located between the bottom electrode and the top electrode in the horizontal direction. The material of the protective structure 115 may be a metal such as gold, molybdenum, tungsten, aluminum, copper, chromium, titanium, etc., and alloys or multi-layer composite metal materials. If the material is not easy to oxidize, only one layer of the protection structure 115 is needed, and if the material is easy to oxidize, a passivation layer is added above the protection structure 115.
W1: the distance between the bottom electrode 105 and the top electrode 109. In the embodiment shown in FIG. 1, the second end point (inner end, in the present invention, the end or side closer to the center of the active area of the resonator is inner; and correspondingly the first end point is outer, in the present invention, the end or side farther from the center of the active area of the resonator is outer) of the protective structure 115 is horizontally spaced from the top electrode 109 by W0<W +.W1. The specific range is not more than 15. Mu.m.
W2: the distance between the bottom electrode 105 and the same side end of the piezoelectric layer 107. The specific range is as follows: 3-50 μm.
H1: the distance between the protective structure 115 and the piezoelectric layer 107. The specific range is as follows:optionally, an optional
H2: distance between the piezoelectric layer 107 and the substrate 101. The specific range is as follows:optionally, an optional
In the present invention, the numerical ranges mentioned may be median values between the end points or other values in addition to the end points, which are all within the scope of the present invention.
It is noted that in the embodiments of the present invention, the protective structure 115 is provided, but as will be appreciated by those skilled in the art, the protective structure 115 may not be provided in the case where there is a gap between the main body resonant structure of the resonator and the upper surface of the substrate. Here, the bulk resonant structure refers to a sandwich structure region of the resonator from which the top and bottom electrode lead portions are removed. In the present invention, the overlapping region of the bottom electrode, the piezoelectric layer, the top electrode, and the acoustic mirror in the thickness direction of the resonator constitutes the effective region of the resonator. In the present invention, the case where a gap exists between the main resonator structure and the upper surface of the substrate means, in particular, that a gap exists between the main resonator structure and the upper surface of the substrate except for the effective region or the acoustic mirror region.
Because a gap is formed between the main body resonance structure of the sandwich structure of the resonator and the substrate, the frequency of the resonator is not affected by the stress of the substrate. This contributes to the stability of the resonator frequency.
Under the condition that the protection structure 115 is arranged, if the resonator is deformed during working, the protection structure 115 can limit the deformation amount of the resonator, so that the resonator is not easy to deform or break, and the mechanical and electrical performance stability of the device is improved.
Fig. 1B and 1C respectively show the case where the electrode pins are arranged on different sides and the electrode pins are arranged on the same side.
In fig. 1B, the electrode pins 117 and 119 are located on different sides, and the protection structure 115 is divided into two parts. In fig. 1C, the electrode pins 117 and 119 are located on the same side, which is advantageous for the continuity of the protection structure, and the protection structure is an integral body, so that the protection effect is better.
Fig. 2A is a schematic cross-sectional view (in the direction B-B of fig. 2B) of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention. Fig. 2B is a schematic top view of the bulk acoustic wave resonator of fig. 2A in accordance with an exemplary embodiment of the present invention. Fig. 2C and 2D are schematic cross-sectional views (along the C-C and D-D directions, respectively, of fig. 2B) of a bulk acoustic wave resonator according to a further exemplary embodiment of the present invention.
In the embodiment shown in fig. 2A-2D and described later, a passivation layer 116 is provided on the protective structure 115. The material of the protection structure 115 may be, for example, molybdenum, and the material of the protection structure 115 may be the same as or different from the top electrode. The material of the passivation layer 116 may be the same as or different from the material of the passivation layer 111, for example, alN.
In fig. 2A-2D, it can be seen that the guard structure 115 is located outside the bottom electrode in the lateral direction. This avoids overlapping of the inner end of the guard structure 115 and the bottom electrode in the thickness direction of the resonator, compared to the embodiment of fig. 1A, and thus avoids the formation of a small sandwich structure. In the embodiment shown in fig. 2A-2D, the protection structure 115 is not present to affect the performance of the resonator due to the additional sandwich structure.
Fig. 3 is a schematic cross-sectional view of a bulk acoustic wave resonator (similar to the direction B-B in fig. 1B or 1C) according to an exemplary embodiment of the present invention. In order to further reduce the influence of the protective structure on the performance of the resonator, in fig. 3, a bottom electrode is arranged, which is located inside the acoustic mirror, in projection in the thickness direction of the resonator.
Fig. 4A is a schematic cross-sectional view (in the direction B-B of fig. 4B) of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention. Fig. 4B is a schematic top view of the bulk acoustic wave resonator of fig. 4A in accordance with an exemplary embodiment of the present invention.
As shown in fig. 4A-4B, the inner end of the second portion of the protective structure 115 is directly connected to the piezoelectric layer, so that the protective structure in the embodiment shown in fig. 4A and 4B is a semi-floating structure, as compared to the floating structure of the protective structure 115 in the previous embodiment.
In a further embodiment, as shown in fig. 4A, the connection of the inner end of the second portion of the protective structure 115 to the piezoelectric layer is located beyond the edge of the bottom electrode in the lateral direction of the resonator. The semi-suspension structure is equivalent to a simple spring, can buffer the external stress suffered by the device to a certain extent, and simultaneously, compared with the full-suspension structure, the mechanical stability of the device is further enhanced.
Fig. 5A to 5F are schematic views illustrating a manufacturing process of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention. The process of manufacturing a bulk acoustic wave resonator such as that in fig. 2A is described below with reference to fig. 5A-5F.
First, as shown in fig. 5A, after etching a pattern on the substrate 101, the sacrificial layer material 102 is filled and then entirely flattened.
Next, as shown in fig. 5B, after the sacrifice layer 104 and the bottom electrode 105 are grown, the bottom electrode 105 is etched to obtain a pattern of the bottom electrode 105.
Again, as shown in fig. 5C, after the piezoelectric layer 107 is grown, the piezoelectric layer 107 and the sacrifice layer 104 are etched.
Thereafter, as shown in fig. 5D, the sacrificial layer 112 is grown and etched to form the structure of fig. 5D.
As shown in fig. 5E, the top electrode 109 and passivation layer 111 are then grown and etched to form the structure of fig. 5E.
Then, as shown in fig. 5F, the sacrificial layers 102 and 104 and 112 are released, forming a floating structure as shown in fig. 5F.
In fig. 5A-5F, the suspended structure of the protective structure is processed simultaneously with the top electrode and passivation layer.
Fig. 6A to 6F are schematic views illustrating a manufacturing process of a bulk acoustic wave resonator according to another exemplary embodiment of the present invention. In fig. 6A-6F, the top electrode and passivation layer are formed first, followed by the formation of a suspended structure of the protective structure.
In fig. 6A, the substrate 101 is etched to fill the material 102, and then planarized.
In fig. 6B, after the sacrifice layer 104 and the bottom electrode 105 are grown, the bottom electrode 105 is etched to obtain a pattern of the bottom electrode.
In fig. 6C, the piezoelectric layer 107, the top electrode 109, and the passivation layer 111 are grown, and then the piezoelectric layer 107, the top electrode 109, and the passivation layer 111 are etched.
In fig. 6D, sacrificial layer 112 is grown and sacrificial layer 112 is etched to form the structure of fig. 6D.
In fig. 6E, the protective structure layer 115 and passivation layer 116 are grown and etched to form the structure of fig. 6E.
In fig. 6F, sacrificial layers 102 and 104 and 112 are released, forming a floating structure as shown in fig. 6F.
As can be appreciated by those skilled in the art, bulk acoustic wave resonators according to the present invention can be used to form filters.
Based on the above, the invention provides the following technical scheme:
1. a bulk acoustic wave resonator comprising:
a substrate;
an acoustic mirror;
a bottom electrode having a bottom electrode pin;
a top electrode having a top electrode pin;
a piezoelectric layer disposed between the bottom electrode and the top electrode,
wherein:
a first gap exists between a sandwich structure formed by the bottom electrode, the top electrode and the piezoelectric layer and the upper surface of the substrate, and the first gap enables a main body resonance structure formed by the bottom electrode, the piezoelectric layer and the top electrode of the resonator to be in non-contact with the substrate.
2. The resonator according to claim 1, further comprising:
and a protective structure layer including a first portion connected to the upper surface of the substrate and a second portion connected to the inner end of the first portion, the second portion extending above the piezoelectric layer along the piezoelectric layer and forming a second gap with the piezoelectric layer in a thickness direction at least a portion of the second portion, and the second portion being spaced apart from the top electrode in a lateral direction.
3. The resonator according to claim 2, wherein:
the second gap extends over the entire portion of the second portion, an inner end of the second portion being spaced apart from the piezoelectric layer in a thickness direction of the resonator.
4. The resonator according to claim 3, wherein:
the inner end of the second portion overlaps with a projection of the bottom electrode edge in the thickness direction of the resonator.
5. The resonator according to claim 3, wherein:
the inner end of the second portion and the projection of the bottom electrode edge in the thickness direction of the resonator are spaced apart from each other.
6. The resonator according to claim 2, wherein:
the inner end of the second portion is connected with the piezoelectric layer.
7. The resonator according to claim 6, wherein:
the inner end of the second portion and the projection of the bottom electrode in the thickness direction of the resonator are spaced apart from each other.
8. The resonator according to any of claims 2-7, wherein:
the first gap communicates with the second gap.
9. The resonator according to claim 8, wherein:
the acoustic mirror is an acoustic mirror cavity, and the first gap is communicated with the acoustic mirror cavity.
10. The resonator according to any of claims 2-7, wherein:
the protective structure layer further includes a passivation layer disposed thereon.
11. The resonator according to any of claims 2-7, wherein:
the thickness of the first gap is equal toWithin (1), further within->And/or
The thickness of the second gap is equal toWithin (1), further within->
12. The resonator according to any of claims 1-3, 5-7, wherein:
the projection of the bottom electrode in the thickness direction of the resonator falls within the range of the acoustic mirror.
13. The resonator according to any of claims 2-7, wherein:
the top electrode pin and the bottom electrode pin are positioned on opposite sides of the resonator in the transverse direction;
the protective structure layer is disposed along a perimeter of the resonator active area and includes first and second circumferential portions separated by a top electrode pin and a bottom electrode pin in a circumferential direction.
14. The resonator according to any of claims 2-7, wherein:
the top electrode pin and the bottom electrode pin are positioned on the same side of the resonator in the transverse direction;
the protective structure layer is arranged along the periphery of the resonator effective area, and the top electrode pins and the bottom electrode pins are positioned at gaps of the protective structure layer in the circumferential direction in a top view of the resonator.
15. The resonator according to any of claims 2-7, wherein:
the protective structure layer is the same as the top electrode material.
16. A method of manufacturing a bulk acoustic wave resonator comprising a substrate, an acoustic mirror, a bottom electrode, a piezoelectric layer and a top electrode, the bottom electrode, piezoelectric layer and top electrode forming a sandwich structure, the method comprising the steps of:
(1) Forming a first sacrificial layer, wherein the first sacrificial layer is positioned between a sandwich structure which is formed or is to be formed and the upper surface of the substrate;
(2) Forming a second sacrificial layer which is connected with the first sacrificial layer, covers the piezoelectric layer and extends along the piezoelectric layer to cover a part of the upper surface of the piezoelectric layer;
(3) Forming a protective structure layer, wherein one part of the protective structure layer covers the upper surface of the substrate, the other part of the protective structure layer extends to cover the upper surface of the second sacrificial layer, and the position of the protective structure layer is separated from the top electrode in the transverse direction;
(4) And releasing the first sacrificial layer and the second sacrificial layer, wherein a first gap is formed after the first sacrificial layer is released, a second gap is formed after the second sacrificial layer is released, and the first gap is communicated with the second gap.
17. The method according to claim 16, wherein:
the step (1) comprises: forming a first sacrificial layer between the piezoelectric layer and the underside of the bottom electrode and the upper surface of the substrate;
in the step (3), a protective structure layer and a top electrode are formed at the same time.
18. The method of claim 17, wherein:
the method further comprises forming a passivation layer on the upper surface of the top electrode and/or the upper surface of the protective structure layer prior to step (4).
19. The method according to claim 16, wherein:
in the step (1), a first sacrificial layer is formed between the lower side of a sandwich structure formed by the top electrode, the piezoelectric layer and the bottom electrode and the upper surface of the substrate;
in the step (2), the second sacrificial layer covers the sandwich structure from the upper side and is connected with the first sacrificial layer.
20. The method of claim 19, wherein:
the method further comprises the steps of, prior to forming the second sacrificial layer: an electrode passivation layer is formed on the upper surface of the top electrode.
21. The method according to claim 20, wherein:
the step (3) further comprises the step of disposing a passivation layer of the protective structure layer on the protective structure layer.
22. The method according to claim 16, wherein:
in step (3), another portion of the protective structure layer is entirely located on the upper surface of the second sacrificial layer.
23. The method according to claim 16, wherein:
in step (3), another portion of the protective structure layer covers the upper surface of the second sacrificial layer and covers a portion of the upper surface of the piezoelectric layer.
24. The method of any one of claims 16-23, wherein:
the acoustic mirror is an acoustic mirror cavity;
the method further comprises the steps before the step (1): forming an acoustic mirror cavity on a substrate, filling a cavity sacrificial layer material in the cavity, and enabling the upper surface of the acoustic mirror to be flush with the upper surface of the substrate;
the step (4) further comprises releasing the cavity sacrificial layer material, and the cavity formed after releasing the cavity sacrificial layer material is communicated with the second gap through the first gap.
25. A filter comprising a bulk acoustic wave resonator according to any one of claims 1-15 and a bulk acoustic wave resonator manufactured according to the method of any one of claims 16-24.
26. An electronic device comprising a filter according to claim 25 or a bulk acoustic wave resonator according to any one of claims 1-15 and a bulk acoustic wave resonator manufactured according to the method of any one of claims 16-24.
Although embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.
Claims (26)
1. A bulk acoustic wave resonator comprising:
a substrate;
an acoustic mirror;
a bottom electrode having a bottom electrode pin;
a top electrode having a top electrode pin;
a piezoelectric layer disposed between the bottom electrode and the top electrode,
wherein:
a first gap exists between a sandwich structure formed by the bottom electrode, the top electrode and the piezoelectric layer and a surface of the substrate, which is flush with the upper surface of the acoustic mirror, and the first gap enables a main body resonance structure formed by the bottom electrode, the piezoelectric layer and the top electrode of the resonator to be in non-contact with the substrate, and the first gap is located between the acoustic mirror and the lower surface of the main body resonance structure in the thickness direction of the resonator.
2. The resonator of claim 1, further comprising:
and a protective structure layer including a first portion connected to the upper surface of the substrate and a second portion connected to the inner end of the first portion, the second portion extending above the piezoelectric layer along the piezoelectric layer and forming a second gap with the piezoelectric layer in a thickness direction at least a portion of the second portion, and the second portion being spaced apart from the top electrode in a lateral direction.
3. The resonator of claim 2, wherein:
the second gap extends over the entire portion of the second portion, an inner end of the second portion being spaced apart from the piezoelectric layer in a thickness direction of the resonator.
4. A resonator as claimed in claim 3, wherein:
the inner end of the second portion overlaps with a projection of the bottom electrode edge in the thickness direction of the resonator.
5. A resonator as claimed in claim 3, wherein:
the inner end of the second portion and the projection of the bottom electrode edge in the thickness direction of the resonator are spaced apart from each other.
6. The resonator of claim 2, wherein:
the inner end of the second portion is connected with the piezoelectric layer.
7. The resonator of claim 6, wherein:
the inner end of the second portion and the projection of the bottom electrode in the thickness direction of the resonator are spaced apart from each other.
8. The resonator according to any of claims 2-7, wherein:
the first gap communicates with the second gap.
9. The resonator of claim 8, wherein:
the acoustic mirror is an acoustic mirror cavity, and the first gap is communicated with the acoustic mirror cavity.
10. The resonator according to any of claims 2-7, wherein:
the protective structure layer further includes a passivation layer disposed thereon.
11. The resonator according to any of claims 2-7, wherein:
the thickness of the first gap is equal toWithin (1), further within->And/or
The thickness of the second gap is equal toWithin (1), further within->
12. The resonator according to any of claims 1-3, 5-7, wherein:
the projection of the bottom electrode in the thickness direction of the resonator falls within the range of the acoustic mirror.
13. The resonator according to any of claims 2-7, wherein:
the top electrode pin and the bottom electrode pin are positioned on opposite sides of the resonator in the transverse direction;
the protective structure layer is disposed along a perimeter of the resonator active area and includes first and second circumferential portions separated by a top electrode pin and a bottom electrode pin in a circumferential direction.
14. The resonator according to any of claims 2-7, wherein:
the top electrode pin and the bottom electrode pin are positioned on the same side of the resonator in the transverse direction;
the protective structure layer is arranged along the periphery of the resonator effective area, and the top electrode pins and the bottom electrode pins are positioned at gaps of the protective structure layer in the circumferential direction in a top view of the resonator.
15. The resonator according to any of claims 2-7, wherein:
the protective structure layer is the same as the top electrode material.
16. A method of manufacturing a bulk acoustic wave resonator comprising a substrate, an acoustic mirror, a bottom electrode, a piezoelectric layer and a top electrode, the bottom electrode, piezoelectric layer and top electrode forming a sandwich structure, the method comprising the steps of:
(1) Forming a first sacrificial layer, wherein the first sacrificial layer is positioned between a sandwich structure which is formed or is to be formed and the upper surface of the substrate;
(2) Forming a second sacrificial layer which is connected with the first sacrificial layer, covers the piezoelectric layer and extends along the piezoelectric layer to cover a part of the upper surface of the piezoelectric layer;
(3) Forming a protective structure layer, wherein one part of the protective structure layer covers the upper surface of the substrate, the other part of the protective structure layer extends to cover the upper surface of the second sacrificial layer, and the position of the protective structure layer is separated from the top electrode in the transverse direction;
(4) And releasing the first sacrificial layer and the second sacrificial layer, wherein a first gap is formed after the first sacrificial layer is released, a second gap is formed after the second sacrificial layer is released, and the first gap is communicated with the second gap.
17. The method according to claim 16, wherein:
the step (1) comprises: forming a first sacrificial layer between the piezoelectric layer and the underside of the bottom electrode and the upper surface of the substrate;
in the step (3), a protective structure layer and a top electrode are formed at the same time.
18. The method according to claim 17, wherein:
the method further comprises forming a passivation layer on the upper surface of the top electrode and/or the upper surface of the protective structure layer prior to step (4).
19. The method according to claim 16, wherein:
in the step (1), a first sacrificial layer is formed between the lower side of a sandwich structure formed by the top electrode, the piezoelectric layer and the bottom electrode and the upper surface of the substrate;
in the step (2), the second sacrificial layer covers the sandwich structure from the upper side and is connected with the first sacrificial layer.
20. The method according to claim 19, wherein:
the method further comprises the steps of, prior to forming the second sacrificial layer: an electrode passivation layer is formed on the upper surface of the top electrode.
21. The method according to claim 20, wherein:
the step (3) further comprises the step of disposing a passivation layer of the protective structure layer on the protective structure layer.
22. The method according to claim 16, wherein:
in step (3), another portion of the protective structure layer is entirely located on the upper surface of the second sacrificial layer.
23. The method according to claim 16, wherein:
in step (3), another portion of the protective structure layer covers the upper surface of the second sacrificial layer and covers a portion of the upper surface of the piezoelectric layer.
24. The method of any one of claims 16-23, wherein:
the acoustic mirror is an acoustic mirror cavity;
the method further comprises the steps before the step (1): forming an acoustic mirror cavity on a substrate, filling a cavity sacrificial layer material in the cavity, and enabling the upper surface of the acoustic mirror to be flush with the upper surface of the substrate;
the step (4) further comprises releasing the cavity sacrificial layer material, and the cavity formed after releasing the cavity sacrificial layer material is communicated with the second gap through the first gap.
25. A filter comprising a bulk acoustic wave resonator according to any of claims 1-15 and a bulk acoustic wave resonator manufactured according to the method of any of claims 16-24.
26. An electronic device comprising a filter according to claim 25 or a bulk acoustic wave resonator according to any of claims 1-15 and a bulk acoustic wave resonator manufactured according to the method of any of claims 16-24.
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| CN117081533A (en) * | 2022-12-14 | 2023-11-17 | 北京芯溪半导体科技有限公司 | Bulk acoustic wave resonator, preparation method thereof, filter and electronic equipment |
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