CN111010140A - Resonator with gap structure arranged on inner side of protrusion structure and electronic equipment - Google Patents

Resonator with gap structure arranged on inner side of protrusion structure and electronic equipment Download PDF

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Publication number
CN111010140A
CN111010140A CN201910470204.4A CN201910470204A CN111010140A CN 111010140 A CN111010140 A CN 111010140A CN 201910470204 A CN201910470204 A CN 201910470204A CN 111010140 A CN111010140 A CN 111010140A
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Prior art keywords
resonator
wing
base layer
protruding
top electrode
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Inventor
张孟伦
庞慰
杨清瑞
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Tianjin University
ROFS Microsystem Tianjin Co Ltd
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Tianjin University
ROFS Microsystem Tianjin Co Ltd
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Priority to CN201910470204.4A priority Critical patent/CN111010140A/en
Priority to PCT/CN2020/076214 priority patent/WO2020238296A1/en
Publication of CN111010140A publication Critical patent/CN111010140A/en
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/46—Filters
    • H03H9/54—Filters comprising resonators of piezoelectric or electrostrictive material
    • H03H9/547—Notch filters, e.g. notch BAW or thin film resonator filters
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/02007—Details of bulk acoustic wave devices
    • H03H9/02086—Means for compensation or elimination of undesirable effects
    • H03H9/0211—Means for compensation or elimination of undesirable effects of reflections
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/02007—Details of bulk acoustic wave devices
    • H03H9/02086—Means for compensation or elimination of undesirable effects
    • H03H9/02118—Means for compensation or elimination of undesirable effects of lateral leakage between adjacent resonators
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
    • H03H9/205—Constructional features of resonators consisting of piezoelectric or electrostrictive material having multiple resonators

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  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)

Abstract

The invention relates to a bulk acoustic wave resonator comprising: a substrate; an acoustic mirror; a bottom electrode disposed over the substrate; a top electrode facing the bottom electrode and having an electrode connection portion; and a piezoelectric layer disposed over the bottom electrode and between the bottom electrode and the top electrode, wherein: the edge of the top electrode is provided with a protruding structure and a gap structure which is positioned at the inner side of the protruding structure and forms a gap. The invention also relates to a filter having the bulk acoustic wave resonator, and an electronic device having the filter. Based on the scheme, the invention can inhibit the energy leakage of the resonator and reduce the noise wave generation in the resonator.

Description

Resonator with gap structure arranged on inner side of protrusion structure and electronic equipment
Technical Field
Embodiments of the present invention relate to the field of semiconductors, and in particular, to a bulk acoustic wave resonator, a filter having the resonator, and an electronic device having the filter.
Background
Fig. 5A is a top view of a bulk acoustic wave resonator in the prior art, and fig. 5B is a schematic cross-sectional view taken along line a1-a2 in fig. 5A. In fig. 5A and 5B, the structures corresponding to the reference numerals are as follows:
10: substrate
20: an acoustic mirror, in this case a cavity, may also be used with a Bragg reflector or other equivalent acoustic wave reflecting structure
30: bottom electrode
40: piezoelectric film (piezoelectric layer)
50: top electrode
60: top electrode pin
AR: effective acoustic area (acoustoelectric coupling area)
The structure not shown in fig. 5A and 5B further includes a part of an auxiliary process layer, a protective layer, a bottom electrode pin, and the like.
In actual operation, the AR region of the resonator shown in fig. 5A and 5B not only generates useful piston mode vibration, but also generates unfavorable laterally-propagating sound waves, and these lateral-mode sound waves propagate outside the AR region, causing energy loss and performance degradation of the resonator, and further degrading the performance of the electronic device using the resonator, such as the insertion loss, roll-off, bandwidth and other key performance parameters of the filter.
Fig. 5C shows a resonator structure for suppressing the leakage of acoustic waves in the prior art. The improvement of the structure relative to that in fig. 5B is that: a raised structure is added to the edge of the top electrode 50 that creates an acoustic impedance mismatch area at the edge of the AR region, thereby reflecting acoustic waves propagating laterally outward from the AR region back into the AR region and thereby suppressing energy loss. The structure has the advantages that the Q value of the resonator is improved remarkably, and the defect that noise waves in the resonator are increased is caused because the protruding structure is still in the sound-electricity coupling area AR, and the electrical performance of the protruding structure is influenced when the protruding structure reflects sound waves.
Fig. 5D shows another resonator structure for suppressing the leakage of acoustic waves in the prior art. The improvement of the method relative to the method of FIG. 5C is that: in addition to adding a bump structure to the edge of the top electrode 50, the top electrode 50 is further extended outward to form an air foil (overhang foil), and the leads 60 also form a dome structure (hereinafter referred to as overhang foil structure). Since only acoustic vibration exists in the added suspension wing structure, the existing acoustoelectric coupling effect is far smaller than that of the protrusion structure, and therefore noise generated by the suspension wing structure when the suspension wing structure reflects sound waves is remarkably smaller than that of the protrusion structure. The structure in fig. 5D has a disadvantage that when the sound wave propagates outward from the AR, the sound wave first reacts with the protruding structure to form reflection and generate considerable noise, and in addition, the sound wave reflected by the suspended wing structure also reacts with the protruding structure to generate a part of noise, so that the structure in fig. 5D still generates more noise, thereby degrading the performance of the resonator.
Disclosure of Invention
The present invention is proposed to reduce noise generation in a resonator while suppressing energy leakage of the resonator.
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 disposed over the substrate;
a top electrode facing the bottom electrode and having an electrode connection portion; and
a piezoelectric layer disposed above the bottom electrode and between the bottom electrode and the top electrode,
wherein:
the edge of the top electrode is provided with a protruding structure and a gap structure which is positioned at the inner side of the protruding structure and forms a gap.
Optionally, the resonator comprises a cantilever forming the void structure.
Optionally, the suspension wing comprises a single suspension wing structure.
Further optionally, the single-suspended wing structure has a base layer portion and a suspended wing portion, the base layer portion is located at the top electrode; at least a portion of the void formed by the overhang portion is located between the base layer portion and the projection structure. Optionally, the lateral distance between the protruding structure and the base layer is in a range of 0.5-5 μm (optionally 1-3 μm), and this dimension directly has an important role in forming a constructive superposition of the sound wave reflected by BO and the sound wave reflected by the suspension wing, and it is necessary to prevent the mutual interference caused by too close distance and the insignificant interference caused by too far sound wave attenuation; and/or the lateral distance between the outer edge of the protruding structure and the outer edge of the flap portion is in the range of 0- ± 5 μm (optionally 0- ± 3 μm); and/or the longitudinal distance between the top of the protruding structures and the flap portions is in the range of 0-5 μm (optionally 0.5-3 μm). Or optionally, the overhang portion has a rising portion connected to the base layer portion, and the rising portion has a stepped shape. Or alternatively, the overhang portion and the protruding structure at least partially coincide in a thickness direction of the resonator. Or alternatively, the overhang portion has a raised portion connected to the base layer portion, the raised portion forming an angle with the top surface of the top electrode in the range of 15 ° -90 ° (alternatively 40 ° -70 °). Or alternatively, the end of the top electrode is formed with an additional overhang portion.
Optionally, the single-suspended wing structure has a base layer portion and a suspended wing portion, and the base layer portion is located on the top electrode; the base layer portion is located between the overhang portion and the projection structure. Further optionally, the lateral distance of the protruding structure from the base layer portion is in the range of 0-5 μm (optionally 0.5-3 μm); and/or the lateral width of the flap portion is in the range of 0.5-5 μm (optionally 1-3 μm); and/or the lateral distance between the protruding structures and the overhanging portions is in the range of 1-10 μm (optionally 3-5 μm).
Optionally, the single-suspended wing structure has a base layer portion and a suspended wing portion, and the base layer portion is located on top of the protruding structure. Further optionally, the overhang portion and the base layer portion are at the same level; or the overhang portion includes a rising portion connected to the base layer portion.
Optionally, the suspension wing includes a double-suspension wing structure, and the double-suspension wing structure includes a base layer portion, and a first single-suspension wing structure and a second single-suspension wing structure respectively connected to two sides of the base layer portion. Further optionally, the first single-suspension wing structure and the second single-suspension wing structure are arranged asymmetrically. Or optionally, the base layer portion is located inside the protruding structure and disposed on the top electrode. Or optionally, the base layer portion is disposed on the top of the protruding structure, and further optionally, the base layer portion and the top of the protruding structure are disposed in a laterally staggered manner.
Optionally, the resonator comprises a bridge forming the void structure. Optionally, the bridge is located entirely inside the protruding structure. Or alternatively, the protruding structure is located in a space formed by the bridge.
Optionally, a recessed feature in the void inboard of the protruding feature.
Optionally, the resonator further comprises a cover layer covering the top electrode; and the base layer portion is an integral part of the cover layer. The cover layer may cover only a portion of the top electrode.
Optionally, the gap is filled with air.
According to another aspect of embodiments of the present invention, there is provided a filter including the bulk acoustic wave resonator described above.
According to a further aspect of embodiments of the present invention, there is provided an electronic device including the above-described filter or bulk acoustic wave resonator.
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 partial cross-sectional view of a thin film bulk acoustic resonator according to an exemplary embodiment of the present invention;
fig. 1B is a schematic view exemplarily showing a positional relationship between the protrusion structure and the flap structure;
FIG. 1C is a schematic partial cross-sectional view of a thin film bulk acoustic resonator illustrating an embodiment of a cantilevered wing structure;
FIG. 1D is a schematic partial cross-sectional view of a thin film bulk acoustic resonator according to an exemplary embodiment of the present invention;
FIG. 2A is a schematic partial cross-sectional view of a thin film bulk acoustic resonator according to an exemplary embodiment of the present invention;
FIG. 2B is a schematic partial cross-sectional view of a thin film bulk acoustic resonator according to an exemplary embodiment of the present invention;
FIG. 2C is a schematic partial cross-sectional view of a thin film bulk acoustic resonator according to an exemplary embodiment of the present invention;
FIG. 2D is a schematic partial cross-sectional view of a thin film bulk acoustic resonator according to an exemplary embodiment of the present invention;
FIG. 2E is a schematic partial cross-sectional view of a thin film bulk acoustic resonator according to an exemplary embodiment of the present invention;
FIG. 3A is a schematic partial cross-sectional view of a thin film bulk acoustic resonator according to an exemplary embodiment of the present invention;
FIG. 3B is a schematic partial cross-sectional view of a thin film bulk acoustic resonator according to an exemplary embodiment of the present invention;
FIG. 3C is a schematic partial cross-sectional view of a thin film bulk acoustic resonator according to an exemplary embodiment of the present invention;
FIG. 3D is a schematic partial cross-sectional view of a thin film bulk acoustic resonator according to an exemplary embodiment of the present invention;
FIG. 4 is a schematic partial cross-sectional view of a thin film bulk acoustic resonator according to an exemplary embodiment of the present invention;
fig. 5A is a top view of a prior art bulk acoustic wave resonator;
FIG. 5B is a schematic cross-sectional view taken along line A1-A2 of FIG. 5A;
FIG. 5C is a prior art resonator structure for suppressing acoustic wave leakage;
fig. 5D shows another resonator structure for suppressing the leakage of acoustic waves in the prior art.
Detailed Description
The technical scheme of the invention is further specifically described by the following embodiments and the accompanying drawings. 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.
A bulk acoustic wave resonator according to an embodiment of the present invention is described below with reference to the drawings. It should be noted that, in the embodiments of the present invention, although the thin film bulk acoustic resonator is taken as an example for description, the description may be applied to other types of bulk acoustic resonators.
Fig. 1A is an embodiment of the present invention, which shows a structure of a top electrode edge portion, and is modified in that a suspension wing structure is moved to the inside of a protrusion structure, and in this case, a non-metal material may be used as a material of the suspension wing structure.
Specifically, the various components and materials in FIG. 1A are described as follows:
50: the top electrode is made of metal material, and the material can be selected from molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or the composite of the above metals or alloy thereof.
51: the protrusion structure can be made of non-metal materials, such as: silicon dioxide, silicon nitride, silicon carbide, aluminum nitride, magnesium oxide, aluminum oxide, or other metal oxides, nitrides, polymers, etc., and may also be selected from the same or different metal materials as the top electrode, such as molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, or combinations or alloys thereof.
80 and 81: passivation layer: this layer is an optional protective layer that prevents moisture, oxygen, or other foreign matter from attacking the resonator (this layer is omitted in subsequent embodiments and is not shown). The protective layer may be made of non-metal materials such as silicon dioxide, silicon nitride, silicon carbide, aluminum nitride, magnesium oxide, aluminum oxide, or other metal oxides, nitrides, polymers, etc.
The flap structure comprises a base layer 70 and a structural layer 72, wherein:
70: the suspended wing base layer, which is located above the passivation layer 80 or the top electrode 50, is in contact with the passivation layer 80 or the top electrode 50.
72: the suspension wing structure layer is divided into an inclined ascending part and a horizontal part, an air gap is reserved below the ascending part and the horizontal part, and the gap can be filled with other dielectric materials or polymers.
70 and 72 can be selected from non-metallic materials such as: silicon dioxide, silicon nitride, silicon carbide, aluminum nitride, magnesium oxide, aluminum oxide, or other metal oxides or nitrides or polymers, etc., and metal materials such as molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, or combinations or alloys thereof may also be used.
The overall thickness of the structure layer of the suspension wing can be within the range of
Figure BDA0002080613300000061
(optional)
Figure BDA0002080613300000062
)
In addition, the piezoelectric layer of the bulk wave resonator can be made of materials such as aluminum nitride and zinc oxide, rare earth element doping can be carried out on the materials, and the piezoelectric layer and the electrode layer both have a thin film structure.
The structure in fig. 1A can produce at least one of the following technical effects:
1) the combination of the suspension wings and the protruding structures can obviously improve the sound wave reflection performance, so that the Q value of the resonator is improved.
2) The cantilevered structure is located inside the protruding structure such that when the sound wave propagates outward from the AR, it is first reflected by the cantilevered structure, thereby reducing the amount of sound wave energy transferred to the protruding structure, and thus reducing spurious mode noise generation.
3) The suspended wing structure in the conventional structure is usually an extension of the top electrode, and is generally made of metal, when the suspended wing structure is closer to the piezoelectric layer in the longitudinal direction, a certain acoustic-electric coupling phenomenon still occurs, so that the size design of the suspended wing structure is limited. The structure of the suspension wing in the embodiment can be made of non-metal materials, so that the phenomenon of sound-electricity coupling can be avoided, and the degree of freedom of size design is higher.
4) In the structure, the protruding structure can be positioned in the gap between the suspension wing structure and the piezoelectric layer, so that the shape of the gap formed by the suspension wing structure is changed, the protruding structure and the suspension wing structure can form a certain matching relation, and the acoustic wave reflection performance of the suspension wing structure is adjusted, which does not exist in the traditional structure.
The above description of the technical effect is equally applicable when similar structures are present in other embodiments of the invention.
For the structure of fig. 1A, the dimensions of the suspended wing structure and its positional relationship with the protruding structure have a binding relationship between fig. 1B (the passivation layer 80 has been omitted). Wherein D1 is the distance from the edge of the tab structure to the edge of the tab structure, and ranges from +5 to-5 μm, optionally +3 to-3 μm, such as 2 μm where positive values indicate that the edge of the tab structure is to the right of the edge of the tab structure and negative values indicate that the edge of the tab structure is to the left; d2 represents the distance between the start point of the ascending part of the suspended wing structure and the inner edge of the protruding structure, and the range is 0.5-5 μm, and 1-3 μm; h1 represents the distance between the lower surface of the horizontal portion of the wing-suspending structure and the upper surface of the protrusion structure, and is in the range of 0-5 μm, alternatively 0.5-3 μm, such as 2 μm; theta denotes the acute angle, which the ascending portion of the winglet structure makes with the horizontal, and ranges from 15 deg. to 90 deg., optionally from 40 deg. to 70 deg., for example 50 deg.. The above parameters may be adjusted or selected simultaneously, or only one or two or three of the above parameters may be adjusted.
The shape of the raised portion of the airfoil portion of the proposed structure may also be stepped as shown in fig. 1C, based on certain process conditions. Furthermore, the base layer portion 70 of the overhang structure can also cover only a portion of the top electrode. Optionally, the resonator further comprises a cover layer covering the top electrode; the base layer portion is an integral part of the cover layer. The covering layer may be a passivation layer or other metal material layer. The cover layer may cover only a portion of the top electrode.
In addition, in order to simplify the process and enhance the structural stability of the flap structure, the air gap between the flap structure and the protrusion structure in fig. 1A may be omitted to form the flap-protrusion attachment structure in fig. 1D. At this time, H1 corresponding to the above-mentioned is zero.
Furthermore, the extending direction of the suspension wing structure can also be changed from extending to the protruding structure side to extending to the inner side, thereby forming a structural change as in fig. 2A. The edge of the base structure layer of the flap structure and the inner edge of the protrusion structure have a gap D5 in the range of 0-5 μm, optionally 0.5-3 μm, such as 2 μm; the distance between the starting point of the ascending part of the suspension wing structure and the inner edge of the protrusion structure is D6, and the range is 1-10 μm, and 3-5 μm, such as 2 μm; the width D7 of the structural layer of the flap structure is in the range of 0.5-5 μm, optionally 1-3 μm, such as 2 μm; the angle between the ascending portion of the flap structure and the horizontal direction and the distance between the lower surface of the horizontal portion of the structural layer of the flap structure and the upper surface of the protrusion structure can be referred to as dimension range examples in fig. 1B.
In the present invention, the distance between two members means the shortest straight-line (longitudinal or lateral) distance between the two.
A drop-down portion may also be added to the right side of the angel wing structure in fig. 2A, forming the angel wing-protrusion structure in fig. 2B. Wherein the distance between the starting point of the ascending part and the ending point of the descending part of the suspension wing structure is D8, and the range is 0.5-5 μm, and 1-3 μm can be selected. Further, the distance between the lower surface of the horizontal portion of the wing structure and the protrusion structure, the angle of the rising and falling portions with the horizontal direction may be referred to as H1 and θ of fig. 1B, and the distance from the starting point of the rising portion to the inner edge of the protrusion structure and the distance from the edge of the base layer of the wing structure to the inner edge of the protrusion structure may be referred to as D6 and D5 of fig. 2A.
If the starting point of the ascending portion of the wing structure and the base layer of the wing structure on the left side in fig. 2B are moved to the outside of the protrusion structure, the structure of the embodiment in fig. 2C can be formed. Wherein the distance between the starting point of the left raised portion and the outer edge of the protrusion structure is D10, and the range is 0.5-5 μm, optionally 1-3 μm, such as 2 μm; the distance D9 from the inner edge of the protrusion structure at the end of the right descender is in the range of 0.5-5 μm, alternatively 1-3 μm, such as 2 μm. In addition, the included angle between the ascending portion and the descending portion and the horizontal direction can refer to θ in fig. 1B, and the distance between the lower surface of the horizontal portion of the suspension wing structure and the upper surface of the protruding structure can refer to H1 in fig. 1B.
The cantilevered structure of fig. 2A may also be moved to the upper surface of the protruding structure to form the embodiment of fig. 2D. Wherein the horizontal distance between the lower surface of the horizontal part of the suspension wing structure and the upper surface of the protruding structure is H3, and the range is 0-5 μm, optionally 0.5-2 μm; the width of the flap structure is D11, and the range is 0.5-5 μm, optionally 1-3 μm.
The raised portion of the airfoil configuration of fig. 2D may also be omitted, based on particular process conditions, and changed to the straight version of fig. 2E.
In addition, the double-suspension-wing-protrusion structure of fig. 3A can also be formed by combining the suspension wing structure of fig. 2A with fig. 1A. Wherein the relevant dimensions of the left-hand flap structure 72 are as described with reference to fig. 1B, the base layer width of the flap structure is D3, in the range of 1-10 μm, optionally 3-5 μm, such as 2 μm, and the right-hand flap structure 73 and the left-hand flap structure 72 remain symmetrical. By adopting the double-suspension wing structure, the reflection capability to sound waves can be further enhanced.
Since there is a protruding structure under the left suspension wing structure 72 and no protruding structure under the right suspension wing structure 73, the reflection effect of the two suspension wing structures on the sound wave is not symmetrical, and for optimizing the reflection effect, an asymmetrical double suspension wing structure, such as the structure shown in fig. 3B, in which the horizontal portions of the two suspension wing structures are not equal in length, can be adopted. Wherein the horizontal portion of the right-side wing structure has a length D4 that differs from the horizontal portion of the left-side wing structure by a length in the range of +5 to-5 μm, optionally +3 to-3 μm, such as 2 μm, wherein positive values indicate that the right side is longer than the left side and negative values indicate that the left side is shorter.
Besides adopting the asymmetrical strategy of the double-suspension wing structure with unequal horizontal parts, the asymmetrical arrangement of the double-suspension wing structure with unequal horizontal parts in fig. 3C can be adopted. The height H2 between the two wing structures 73 and 72 (based on the surface below) is in the range of +5 to-5 μm, optionally +3 to-3 μm, e.g. 2 μm, positive values indicate that the right wing structure 73 is higher than the left wing structure 72, and negative values are opposite.
In addition, the base layer 70 of the two-wing structure may also be moved to the upper surface of the protrusion structure 51, thereby forming the embodiment structure in fig. 3D. The right-hand flap structure 73 and the left-hand flap structure 72 may adopt the symmetrical dimensional relationship of fig. 3A, or the asymmetrical dimensional relationship of fig. 3B and 3C. Furthermore, the two ends of the base layer 70 of the suspension structure need not be aligned with the two side edges of the bump structure, but may be maintained at distances D12 and D13, respectively, D12 ranging from +0.5 to +3 μm or-0.5 to 3 μm, optionally +1 to +2 μm or optionally-1 to 2 μm, such as 1 μm, wherein positive values indicate that the base layer ends are outside the upper surface of the bump, negative values indicate that they are within the upper surface of the bump, D13 ranges refer to D12, and the positive and negative values are as described for D12.
Furthermore, the positional features of the flap structure of the present invention can be combined with conventional flap-tabs to yield the embodiment shown in fig. 4. Wherein the structures corresponding to reference numerals 51 and 52 constitute a conventional flap-protrusion structure; reference numeral 53 is an optional recessed structure.
Based on the above, the present invention provides a bulk acoustic wave resonator, comprising:
a substrate;
an acoustic mirror;
a bottom electrode disposed over the substrate;
a top electrode facing the bottom electrode and having an electrode connection portion; and
a piezoelectric layer disposed above the bottom electrode and between the bottom electrode and the top electrode,
wherein:
the edge of the top electrode is provided with a protruding structure and a gap structure which is positioned at the inner side of the protruding structure and forms a gap.
As described above, the void may be an air gap or a filled gap filled with a material such as a dielectric material or a polymer.
In the present invention, when the sound wave propagates laterally outward from the AR, the inner side of the member reflects the sound wave first, and the outer side of the member reflects the sound wave later, in other words, the inner side and the outer side are determined in order in the propagation direction of the sound wave.
The gap structure may be formed by a flap (single flap or double flaps) or a bridge structure. In the case of a double-flap, the two flaps may be arranged asymmetrically.
Based on the above, the invention further provides a filter, which includes a plurality of bulk acoustic wave resonators. The invention also provides an electronic device comprising the filter or the bulk acoustic wave resonator.
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 (27)

1. A bulk acoustic wave resonator comprising:
a substrate;
an acoustic mirror;
a bottom electrode disposed over the substrate;
a top electrode facing the bottom electrode and having an electrode connection portion; and
a piezoelectric layer disposed above the bottom electrode and between the bottom electrode and the top electrode,
wherein:
the edge of the top electrode is provided with a protruding structure and a gap structure which is positioned at the inner side of the protruding structure and forms a gap.
2. The resonator of claim 1, wherein:
the resonator includes a suspension wing forming the void structure.
3. The resonator of claim 2, wherein:
the suspension wing comprises a single suspension wing structure.
4. The resonator of claim 3, wherein:
the single-suspended wing structure is provided with a basic layer part and a suspended wing part, and the basic layer part is positioned on the top electrode;
at least a portion of the void formed by the overhang portion is located between the base layer portion and the projection structure.
5. The resonator of claim 4, wherein:
the lateral distance (D2) between the protruding structure and the base layer portion is in the range of 0.5-5 μm, optionally 1-3 μm; and/or the lateral distance (D1) between the outer edge of the protruding structure and the outer edge of the flap portion is in the range of 0- + -5 μm, optionally 0- + -3 μm; and/or the longitudinal distance (H1) between the top of the protruding structures and the flap portions is in the range of 0-5 μm, optionally 0.5-3 μm.
6. The resonator of claim 4, wherein:
the overhang portion has a rising portion connected to the base layer portion, the rising portion being in a stepped shape.
7. The resonator of claim 4, wherein:
the overhang portion and the protrusion structure at least partially overlap in a thickness direction of the resonator.
8. The resonator of claim 4, wherein:
the overhang portion has a raised portion connected to the base layer portion, the raised portion forming an angle with the top surface of the top electrode in the range of 15-90 °, optionally 40-70 °.
9. The resonator of claim 4, wherein:
the tip of the top electrode is formed with an additional overhang portion.
10. The resonator of claim 3, wherein:
the single-suspended wing structure is provided with a basic layer part and a suspended wing part, and the basic layer part is positioned on the top electrode;
the base layer portion is located between the overhang portion and the projection structure.
11. The resonator of claim 10, wherein:
the lateral distance (D5) of the protruding structure from the base layer portion is in the range of 0-5 μm, optionally 0.5-3 μm; and/or the lateral width (D7) of the flap portion is in the range of 0.5-5 μm, optionally 1-3 μm; and/or the lateral distance (D6) between the protruding structures and the overhanging portions is in the range of 1-10 μm, optionally 3-5 μm.
12. The resonator of claim 3, wherein:
the single-suspended wing structure has a base layer portion and a suspended wing portion, the base layer portion being located at a top of the protruding structure.
13. The resonator of claim 12, wherein:
the suspension wing part and the base layer part are positioned on the same horizontal plane; or the overhang portion includes a rising portion connected to the base layer portion.
14. The resonator of claim 2, wherein:
the hanging wing comprises a double-hanging-wing structure, wherein the double-hanging-wing structure comprises a basic layer part, a first single-hanging-wing structure and a second single-hanging-wing structure, and the first single-hanging-wing structure and the second single-hanging-wing structure are respectively connected to two sides of the basic layer part.
15. The resonator of claim 14, wherein:
the first single-suspension wing structure and the second single-suspension wing structure are arranged asymmetrically.
16. The resonator of claim 14, wherein:
the base layer portion is located inside the protruding structure and disposed on the top electrode.
17. The resonator of claim 14, wherein:
the base layer portion is disposed on top of the protrusion structure.
18. The resonator of claim 17, wherein:
the base layer portion and the top portion of the protruding structure are arranged in a staggered mode in the transverse direction.
19. The resonator of claim 1, wherein:
the resonator includes a bridge portion forming the void structure.
20. The resonator of claim 19, wherein:
the bridge is located entirely inside the protruding structure.
21. The resonator of claim 19, wherein:
the protrusion structure is located in a space formed by the bridge portion.
22. The resonator of claim 1, wherein:
a recessed feature in the void inboard of the protruding feature.
23. The resonator of claim 4 or 14, wherein:
the resonator further comprises a cover layer covering the top electrode;
the base layer portion is an integral part of the cover layer.
24. The resonator of claim 23, wherein:
the cover layer covers only a portion of the top electrode.
25. The resonator of any one of claims 1-24, wherein:
the gap is filled with air.
26. A filter comprising the bulk acoustic wave resonator according to any one of claims 1-25.
27. An electronic device comprising the filter of claim 26 or the bulk acoustic wave resonator of any of claims 1-25.
CN201910470204.4A 2019-05-31 2019-05-31 Resonator with gap structure arranged on inner side of protrusion structure and electronic equipment Pending CN111010140A (en)

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PCT/CN2020/076214 WO2020238296A1 (en) 2019-05-31 2020-02-21 Resonator of which gap structure is provided on inner side of projection structure, and electronic device

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