CN111313859A - 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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- 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
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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 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 is formed between a sandwich structure consisting of 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 not in contact with the substrate. The resonator may further include a protective structure layer having a first portion and a second portion, the first portion being connected to the upper surface of the base, an outer end of the second portion being connected to an inner end of the first portion, the second portion extending along the piezoelectric layer to above the piezoelectric layer with at least a portion of the second portion forming a second gap with the piezoelectric layer in the thickness direction, and the second portion being spaced apart from the top electrode in the 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 in particular, to a bulk acoustic wave resonator, a method of manufacturing the bulk acoustic wave resonator, a filter, and an electronic device having the bulk acoustic wave resonator or the filter.
Background
Electronic devices have been widely used as basic elements of electronic equipment, 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 will change the world in the future still need to rely on electronic devices as a foundation.
Film Bulk Acoustic Resonator (FBAR, also called Bulk Acoustic Resonator, BAW for short) is playing an important role in the communication field as an important member of piezoelectric devices, especially FBAR filters have increasingly large market share in the field of radio frequency filters, FBARs have excellent characteristics of small size, high resonance frequency, high quality factor, large power capacity, good roll-off effect and the like, the filters gradually replace traditional Surface Acoustic Wave (SAW) filters and ceramic filters, play a great role in the radio frequency field of wireless communication, and the advantage of high sensitivity can also be applied to the sensing fields of biology, physics, medicine and the like.
The structural main body of the film bulk acoustic resonator is a sandwich structure consisting of an electrode, a piezoelectric film and an electrode, 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 the input electrical signal into mechanical resonance using the inverse piezoelectric effect, and converts the mechanical resonance into an electrical signal for output using the piezoelectric effect.
High frequency resonators with high quality factor and low dynamic impedance are preferred for integrated oscillators. In recent years, as the package size of the resonator is reduced, the frequency drift of the resonator caused by the influence of external stress is more serious, and the performance of the oscillator and the stability thereof are seriously influenced.
With the rapid development of integrated circuit technology, the frequency stability of FBAR resonators is increasingly important. In order to adapt to the trend of miniaturization, it is necessary to solve or alleviate the frequency stability problem of the FBAR resonator.
Disclosure of Invention
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 consisting of 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 free from contact with the substrate.
Optionally, the resonator further includes a protective structure layer including a first portion and a second portion, the first portion being connected to the upper surface of the substrate, an outer end of the second portion being connected to an inner end of the first portion, the second portion extending along the piezoelectric layer above the piezoelectric layer with 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 embodiment of the invention also relates to a method for manufacturing the bulk acoustic wave resonator, wherein the bulk acoustic wave resonator comprises a substrate, an acoustic mirror, a bottom electrode, a piezoelectric layer and a top electrode, and 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 the formed or to-be-formed sandwich structure and the upper surface of the substrate;
(2) forming a second sacrificial layer contiguous with the first sacrificial layer and covering the piezoelectric layer and extending along the piezoelectric layer over a portion 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 lower sides of the piezoelectric layer and the bottom electrode and the upper surface of the substrate; in the step (3), the protective structure layer and the top electrode are formed simultaneously.
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 part of the protective structure layer is entirely located on the upper surface of the second sacrificial layer. Or optionally, in step (3), another part of the protective structure layer covers the upper surface of the second sacrificial layer and covers the upper surface of the piezoelectric layer.
Embodiments of the present invention also relate to a filter comprising the bulk acoustic wave resonator described above.
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, and in which:
FIG. 1A is a schematic cross-sectional view (along 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;
figure 1B is a schematic top view of the bulk acoustic wave resonator of figure 1A, according to an exemplary embodiment of the present invention;
figure 1C is a schematic top view of the bulk acoustic wave resonator of figure 1A, according to an exemplary embodiment of the present invention;
FIG. 2A is a schematic cross-sectional view (along direction B-B of FIG. 2B) of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention;
figure 2B is a schematic top view of the bulk acoustic wave resonator of figure 2A, according to an exemplary embodiment of the present invention;
FIG. 2C is a schematic cross-sectional view (along the direction C-C of FIG. 2B) of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention;
FIG. 2D is a schematic cross-sectional view (along direction D-D of FIG. 2B) of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention;
FIG. 3 is a schematic cross-sectional view (similar to the direction B-B in FIG. 1B or FIG. 1C) of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention;
FIG. 4A is a schematic cross-sectional view (along direction B-B of FIG. 4B) of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention;
figure 4B is a schematic top view of the bulk acoustic wave resonator of figure 4A, according to an exemplary embodiment of the present invention;
FIGS. 5A-5F are schematic diagrams of a bulk acoustic wave resonator manufacturing process 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 by the following embodiments and the accompanying drawings. In the specification, the same or similar reference numerals denote the same or similar components. The following description of the embodiments of the present invention with reference to the accompanying drawings is intended to explain the general inventive concept of the present invention and should not be construed as limiting the invention.
Fig. 1A is a schematic cross-sectional view (along 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, according to an exemplary embodiment of the present invention. Fig. 1C is a schematic top view of the bulk acoustic wave resonator of fig. 1A, according to an exemplary embodiment of the present invention.
In fig. 1A-1C, the reference numerals denote the following:
101: substrates, e.g. silicon or the like
103: the cavity, or other acoustic mirror structures, e.g. Bragg reflector
105: a bottom electrode not in contact with the substrate 101 and having an air gap
107: the piezoelectric layer, the part of the piezoelectric layer outside the bottom electrode (the part inside the main body resonance structure) and the substrate 101 are not in contact, and an air gap exists
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 guard 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 portion that is free from connection to other layers is a second portion 115b, 115b being 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 protection structure 115 may be a metal, such as gold, molybdenum, tungsten, aluminum, copper, chromium, titanium, and the like, and an alloy or a multi-layer composite metal material. If the material is not easily oxidized, only one layer of the protection structure 115 is needed, and if the material is easily oxidized, a passivation layer should be added on 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 (the inner end, in the present invention, the end or side near the center of the active area of the resonator is the inner end; correspondingly, the first end point is the outer end, in the present invention, the end or side far from the center of the active area of the resonator is the outer end) of the guard structure 115 is at a horizontal distance W from the top electrode 109 of 0< W ≦ W1. The specific range is not more than 15 μm.
W2: the distance between the bottom electrode 105 and the end of the same side of the piezoelectric layer 107. The specific ranges are as follows: 3-50 μm.
H1: the distance between the guard structure 115 and the piezoelectric layer 107. The specific ranges are as follows:
optional
H2: the distance between the piezoelectric layer 107 and the base 101. The specific ranges are as follows:
optional
In the present invention, the numerical ranges mentioned may be, besides the end points, the median values between the end points or other values, and are within the protection scope of the present invention.
It is noted that in the embodiments of the present invention, the protection structure 115 is provided, but as can be understood by those skilled in the art, in the case that there is a gap between the main body resonance structure of the resonator and the upper surface of the substrate, the protection structure 115 may not be provided. Here, the bulk resonance structure refers to a sandwich structure region of the resonator excluding the top and bottom electrode lead portions. In the present invention, the overlapping area of the bottom electrode, the piezoelectric layer, the top electrode, and the acoustic mirror in the thickness direction of the resonator constitutes an effective area of the resonator. In the present invention, when there is a gap between the bulk resonator structure and the upper surface of the substrate, it means that there is a gap between the bulk resonator structure and the upper surface of the substrate except for the effective region or the region of the acoustic mirror.
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 influenced 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 deforms 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 leads are arranged on different sides and the electrode leads 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 beneficial to the continuity of the protection structure, and the protection structure is a whole, so that the protection effect is better.
Fig. 2A is a schematic cross-sectional view (along 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, according to an exemplary embodiment of the invention. Fig. 2C and 2D are schematic cross-sectional views (along directions C-C and D-D of fig. 2B, respectively) of a bulk acoustic wave resonator according to further exemplary embodiments of the present invention.
In the embodiments shown in fig. 2A-2D and described subsequently, a passivation layer 116 is disposed on the protective structure 115. The material of the protective structure 115 may be, for example, molybdenum, and the material of the protective 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 the material of the passivation layer 111, for example, AlN, or may be different.
In fig. 2A-2D, it can be seen that the protective structure 115 is located laterally outside the bottom electrode. This avoids an overlap of the inner end of the protective structure 115 and the bottom electrode in the thickness direction of the resonator, compared to the embodiment of fig. 1A, thus avoiding the formation of a small sandwich structure. In the embodiment shown in fig. 2A-2D, the protective structure 115 does not affect the performance of the resonator due to the additional sandwich structure.
Fig. 3 is a schematic cross-sectional view (similar to the direction B-B in fig. 1B or fig. 1C) of a bulk acoustic wave resonator 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 in projection in the thickness direction of the resonator, which bottom electrode is located within the acoustic mirror.
Fig. 4A is a schematic cross-sectional view (along direction B-B of fig. 4B) of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention. Figure 4B is a schematic top view of the bulk acoustic wave resonator of figure 4A, according to 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 protective structure 115 in the previous embodiment being a floating structure.
In a further embodiment, as shown in fig. 4A, the connection of the inner end of the second portion of the protective structure 115 with the piezoelectric layer is located outside 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 of the device to a certain extent, and simultaneously further enhances the mechanical stability of the device compared with a full-suspension structure.
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. A manufacturing process of the bulk acoustic wave resonator in fig. 2A, for example, is explained with reference to fig. 5A to 5F.
First, as shown in fig. 5A, a sacrificial layer material 102 is filled after a pattern is etched on a substrate 101, and then ground flat as a whole.
Next, as shown in fig. 5B, after the sacrificial 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 growing the piezoelectric layer 107, the piezoelectric layer 107 and the sacrificial layer 104 are etched.
Thereafter, as shown in FIG. 5D, 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.
Next, as shown in FIG. 5F, sacrificial layers 102 and 104 and 112 are released, forming a suspended 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 floating structure of the protective structure.
In fig. 6A, the substrate 101 is patterned and filled with a material 102, and then ground flat.
In fig. 6B, after the sacrificial layer 104 and the bottom electrode 105 are grown, the bottom electrode 105 is etched to obtain a bottom electrode pattern.
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, a sacrificial layer 112 is grown and the sacrificial layer 112 is etched to form the structure of fig. 6D.
In fig. 6E, a protective structure layer 115 and a 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 suspended 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 consisting of 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 free from contact with the substrate.
2. The resonator of claim 1, further comprising:
a protective structure layer including a first portion connected to the upper surface of the base and a second portion having an outer end connected to an inner end of the first portion, the second portion extending along the piezoelectric layer to above the piezoelectric layer with 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.
3. The resonator of claim 2, wherein:
the second gap extends over the entire portion of the second section, an inner end of the second section being spaced from the piezoelectric layer in a thickness direction of the resonator.
4. The resonator of claim 3, wherein:
the inner end of the second part is overlapped with the projection of the edge of the bottom electrode in the thickness direction of the resonator.
5. The resonator of claim 3, wherein:
the inner end of the second portion and a 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 contiguous with the piezoelectric layer.
7. The resonator of claim 6, wherein:
the inner end of the second portion and a projection of the bottom electrode in a thickness direction of the resonator are spaced apart from each other.
8. The resonator of any of claims 2-7, wherein:
the first gap is communicated 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 of any of claims 2-7, wherein:
the protective structure layer further includes a passivation layer disposed thereon.
11. The resonator of any of claims 2-7, wherein:
the first gap has a thickness of
Further within the range of
And/or
The thickness of the second gap is within
Further within the range of
12. The resonator of 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 of any of claims 2-7, wherein:
the top electrode pin and the bottom electrode pin are positioned on opposite sides of the resonator in a transverse direction;
the protective structure layer is arranged along the periphery of the resonator active area and comprises a first circumferential portion and a second circumferential portion separated by a top electrode pin and a bottom electrode pin in the circumferential direction.
14. The resonator of 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 pin and the bottom electrode pin are located at the notch of the protective structure layer in the circumferential direction in the top view of the resonator.
15. The resonator of any of claims 2-7, wherein:
the protective structure layer is made of the same material as the top electrode.
16. A method for manufacturing a bulk acoustic wave resonator, the bulk acoustic wave resonator comprising a substrate, an acoustic mirror, a bottom electrode, a piezoelectric layer and a top electrode, the bottom electrode, the piezoelectric layer and the 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 the formed or to-be-formed sandwich structure and the upper surface of the substrate;
(2) forming a second sacrificial layer contiguous with the first sacrificial layer and covering the piezoelectric layer and extending along the piezoelectric layer over a portion 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 of claim 16, wherein:
the step (1) comprises the following steps: forming a first sacrificial layer between the lower sides of the piezoelectric layer and the bottom electrode and the upper surface of the substrate;
in the step (3), the protective structure layer and the top electrode are formed simultaneously.
18. The method of claim 17, wherein:
the method further includes forming a passivation layer on the top electrode upper surface and/or the upper surface of the protective structure layer before step (4).
19. The method of 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:
before forming the second sacrificial layer, the method further comprises the steps of: an electrode passivation layer is formed on the top electrode.
21. The method of 20, wherein:
and the step (3) further comprises the step of arranging a passivation layer of the protective structure layer on the protective structure layer.
22. The method of claim 16, wherein:
in the step (3), the other part of the protective structure layer is entirely located on the upper surface of the second sacrificial layer.
23. The method of 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 following steps before the step (1): forming an acoustic mirror cavity on a substrate, filling cavity sacrificial layer materials in the cavity, and enabling the upper surface of the acoustic mirror to be flush with the upper surface of the substrate;
and the step (4) further comprises releasing the cavity sacrificial layer material, and a cavity formed after the cavity sacrificial layer material is released 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 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.
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 consisting of 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 free from contact with the substrate.
2. The resonator of claim 1, further comprising:
a protective structure layer including a first portion connected to the upper surface of the base and a second portion having an outer end connected to an inner end of the first portion, the second portion extending along the piezoelectric layer to above the piezoelectric layer with 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.
3. The resonator of claim 2, wherein:
the second gap extends over the entire portion of the second section, an inner end of the second section being spaced from the piezoelectric layer in a thickness direction of the resonator.
4. The resonator of claim 3, wherein:
the inner end of the second part is overlapped with the projection of the edge of the bottom electrode in the thickness direction of the resonator.
5. The resonator of claim 3, wherein:
the inner end of the second portion and a 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 contiguous with the piezoelectric layer.
7. The resonator of claim 6, wherein:
the inner end of the second portion and a projection of the bottom electrode in a thickness direction of the resonator are spaced apart from each other.
8. The resonator of any of claims 2-7, wherein:
the first gap is communicated 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 of any of claims 2-7, wherein:
the protective structure layer further includes a passivation layer disposed thereon.
11. The resonator of any of claims 2-7, wherein:
the first gap has a thickness of
Further within the range of
And/or
The thickness of the second gap is within
Further within the range of
12. The resonator of 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 of any of claims 2-7, wherein:
the top electrode pin and the bottom electrode pin are positioned on opposite sides of the resonator in a transverse direction;
the protective structure layer is arranged along the periphery of the resonator active area and comprises a first circumferential portion and a second circumferential portion separated by a top electrode pin and a bottom electrode pin in the circumferential direction.
14. The resonator of 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 pin and the bottom electrode pin are located at the notch of the protective structure layer in the circumferential direction in the top view of the resonator.
15. The resonator of any of claims 2-7, wherein:
the protective structure layer is made of the same material as the top electrode.
16. A method for manufacturing a bulk acoustic wave resonator, the bulk acoustic wave resonator comprising a substrate, an acoustic mirror, a bottom electrode, a piezoelectric layer and a top electrode, the bottom electrode, the piezoelectric layer and the 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 the formed or to-be-formed sandwich structure and the upper surface of the substrate;
(2) forming a second sacrificial layer contiguous with the first sacrificial layer and covering the piezoelectric layer and extending along the piezoelectric layer over a portion 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 of claim 16, wherein:
the step (1) comprises the following steps: forming a first sacrificial layer between the lower sides of the piezoelectric layer and the bottom electrode and the upper surface of the substrate;
in the step (3), the protective structure layer and the top electrode are formed simultaneously.
18. The method of claim 17, wherein:
the method further includes forming a passivation layer on the top electrode upper surface and/or the upper surface of the protective structure layer before step (4).
19. The method of 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:
before forming the second sacrificial layer, the method further comprises the steps of: an electrode passivation layer is formed on the top electrode.
21. The method of claim 20, wherein:
and the step (3) further comprises the step of arranging a passivation layer of the protective structure layer on the protective structure layer.
22. The method of claim 16, wherein:
in the step (3), the other part of the protective structure layer is entirely located on the upper surface of the second sacrificial layer.
23. The method of 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 following steps before the step (1): forming an acoustic mirror cavity on a substrate, filling cavity sacrificial layer materials in the cavity, and enabling the upper surface of the acoustic mirror to be flush with the upper surface of the substrate;
and the step (4) further comprises releasing the cavity sacrificial layer material, and a cavity formed after the cavity sacrificial layer material is released 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 the filter of claim 25 or the bulk acoustic wave resonator of any one of claims 1-15 and a bulk acoustic wave resonator manufactured according to the method of any one of claims 16-24.
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