CN115276600A - Film bulk acoustic resonator and preparation method thereof - Google Patents
Film bulk acoustic resonator and preparation method thereof Download PDFInfo
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- CN115276600A CN115276600A CN202211062831.2A CN202211062831A CN115276600A CN 115276600 A CN115276600 A CN 115276600A CN 202211062831 A CN202211062831 A CN 202211062831A CN 115276600 A CN115276600 A CN 115276600A
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- 238000002360 preparation method Methods 0.000 title abstract description 6
- 239000000758 substrate Substances 0.000 claims abstract description 93
- 238000004519 manufacturing process Methods 0.000 claims description 30
- 238000000034 method Methods 0.000 claims description 27
- 239000010409 thin film Substances 0.000 claims description 26
- 239000010408 film Substances 0.000 claims description 24
- 239000000463 material Substances 0.000 claims description 13
- 238000000151 deposition Methods 0.000 claims description 11
- 238000000059 patterning Methods 0.000 claims description 10
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 8
- 238000005530 etching Methods 0.000 claims description 8
- 235000012239 silicon dioxide Nutrition 0.000 claims description 4
- 239000000377 silicon dioxide Substances 0.000 claims description 4
- 229910052710 silicon Inorganic materials 0.000 claims description 3
- 239000010703 silicon Substances 0.000 claims description 3
- 238000010586 diagram Methods 0.000 description 20
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
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- 230000009286 beneficial effect Effects 0.000 description 1
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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
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- 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
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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
- H03H9/02—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
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- 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
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Abstract
The application provides a film bulk acoustic resonator and a preparation method thereof, relates to the technical field of film bulk acoustic devices, and comprises a substrate, wherein a bottom electrode, a piezoelectric layer and a top electrode are sequentially stacked on the substrate, a cavity is formed between the substrate and the bottom electrode, the piezoelectric layer and the top electrode are respectively arranged in areas, overlapped by projection, on the substrate to form an effective area, a first air bridge is formed between the bottom electrode and the piezoelectric layer, a first groove is formed on the piezoelectric layer outside the effective area, the first groove is positioned on one side, deviating from the bottom electrode, of the piezoelectric layer, and the first groove and the first air bridge are correspondingly arranged in the projection direction. The acoustic wave energy passing through the bottom electrode is limited through the first air bridge, and meanwhile, the transverse acoustic wave leakage of the piezoelectric layer is reduced by forming the first groove in the piezoelectric layer of the non-effective area, so that the acoustic wave energy leakage is fully reduced, and the Q value of the resonator is improved.
Description
Technical Field
The application relates to the technical field of film bulk acoustic wave devices, in particular to a film bulk acoustic wave resonator and a preparation method thereof.
Background
A conventional film bulk acoustic resonator is formed of a three-layer laminated structure, as shown in fig. 1, a bottom electrode, a piezoelectric layer, and a top electrode are sequentially laminated on a substrate, and an area where the bottom electrode, the piezoelectric layer, and the top electrode overlap is an active area. The resonator vibrates up and down during operation to generate standing waves to form resonance, but partial acoustic energy leaks in the non-active area, so that the Q value of the resonator is reduced, as shown by wavy lines in FIG. 1, wherein the wavy lines represent the leaked acoustic energy.
In the prior art, when the problem of acoustic wave energy leakage is solved, basically, a corresponding structure is designed on an electrode to reduce transverse acoustic wave leakage, and a structure for reflecting acoustic waves is designed on the electrode to reflect the acoustic wave leakage passing through the electrode part to the maximum extent. However, the reflection efficiency of the piezoelectric material is greatly reduced for the leakage of the sound wave from the inside of the piezoelectric material, and the sound wave inside the piezoelectric material cannot be reflected well.
Disclosure of Invention
An object of the embodiments of the present application is to provide a film bulk acoustic resonator and a method for manufacturing the same, which can reduce lateral acoustic wave leakage of a piezoelectric material layer, sufficiently reduce leakage of acoustic wave energy, and improve a Q value of the resonator.
In one aspect of the embodiments of the present application, a film bulk acoustic resonator is provided, including a substrate, a bottom electrode, a piezoelectric layer, and a top electrode are sequentially stacked on the substrate, a cavity is formed between the substrate and the bottom electrode, an effective area is formed in an area where projections of the bottom electrode, the piezoelectric layer, and the top electrode on the substrate coincide with each other, a first air bridge is formed between the bottom electrode and the piezoelectric layer, a first groove is formed on the piezoelectric layer outside the effective area, the first groove is located on a side of the piezoelectric layer away from the bottom electrode, and the first groove and the first air bridge are correspondingly arranged in a projection direction.
Optionally, the first recess is in communication with the first air bridge.
Optionally, a second air bridge is formed between the top electrode and the piezoelectric layer, a second groove is formed on the piezoelectric layer outside the active area in the projection direction corresponding to the second air bridge, and the second groove is communicated with the cavity.
Optionally, the second recess is in communication with the second air bridge.
In another aspect of the embodiments of the present application, a method for manufacturing a film bulk acoustic resonator is provided, where the method is used to manufacture the film bulk acoustic resonator, and includes: providing a substrate with a recess formed in one side of the substrate; forming a bottom electrode on one side of the substrate, wherein the groove is formed in the substrate, and forming a cavity between the substrate and the bottom electrode through the groove; depositing a first sacrificial layer in the groove, and patterning the first sacrificial layer to form a first air bridge, wherein the bottom electrode covers the substrate and exposes part of the substrate; forming a piezoelectric layer with a first groove on the patterned bottom electrode, wherein the piezoelectric layer covers the substrate, and the first groove is formed on the side away from the bottom electrode; and forming a top electrode on the piezoelectric layer, patterning the top electrode, covering the piezoelectric layer by the top electrode, and exposing the area of the piezoelectric layer, where the first groove is arranged.
Optionally, the providing a substrate with a groove formed in a side of the substrate comprises: providing the substrate; and etching the substrate to form the groove.
Optionally, a bottom electrode is formed on the substrate on the side provided with the groove, forming a cavity between the substrate and the bottom electrode through the groove; depositing a first sacrificial layer in the groove and patterning the first sacrificial layer for forming a first air bridge, wherein the bottom electrode covers the substrate and exposes a portion of the substrate comprises: etching a groove for forming the first air bridge on the first sacrificial layer; and forming the bottom electrode on the substrate, wherein the cavity is formed at the groove.
Optionally, the forming a piezoelectric layer with a first groove on the patterned bottom electrode, so that the piezoelectric layer covers the substrate, the first groove formed on a side facing away from the bottom electrode includes: depositing a second sacrificial layer at the position of the bottom electrode corresponding to the groove so as to enable the second sacrificial layer to be flush with the surface of the bottom electrode; depositing the piezoelectric layer on the bottom electrode.
Optionally, the forming and patterning a top electrode on the piezoelectric layer, and making the top electrode cover the piezoelectric layer and expose an area of the piezoelectric layer where the first groove is disposed includes: forming the top electrode on the piezoelectric layer and patterning the top electrode such that the top electrode partially covers the piezoelectric layer; and etching the first groove at the position of the exposed piezoelectric layer corresponding to the groove, and simultaneously releasing the first sacrificial layer and the second sacrificial layer to respectively form the cavity and the first air bridge correspondingly.
Optionally, the material of the substrate comprises silicon, and the material of the first sacrificial layer and the second sacrificial layer comprises silicon dioxide.
The thin film bulk acoustic resonator and the preparation method thereof provided by the embodiment of the application are characterized in that a bottom electrode, a piezoelectric layer and a top electrode are sequentially stacked on a substrate with a cavity, the cavity is located between the substrate and the bottom electrode, the piezoelectric layer and the top electrode form an effective area in the area where projections of the substrate coincide respectively, a first air bridge is formed between the bottom electrode and the piezoelectric layer outside the effective area, a first groove corresponding to the projection direction of the first air bridge is formed in the piezoelectric layer, the first groove is located on the side, away from the bottom electrode, of the piezoelectric layer, acoustic wave energy passing through the bottom electrode is limited through the first air bridge, meanwhile, the transverse acoustic wave leakage of the piezoelectric layer is reduced by forming the first groove in the piezoelectric layer in a non-effective area, the leakage of the acoustic wave energy is fully reduced, and the Q value of the resonator is improved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments of the present application will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and that those skilled in the art can also obtain other related drawings based on the drawings without inventive efforts.
Fig. 1 is one of the structural diagrams of the film bulk acoustic resonator provided in this embodiment;
fig. 2 is a second schematic structural diagram of the film bulk acoustic resonator provided in this embodiment;
fig. 3 is a third schematic structural diagram of the film bulk acoustic resonator provided in this embodiment;
fig. 4 is a fourth schematic diagram of the structure of the film bulk acoustic resonator provided in this embodiment;
fig. 5 is a schematic diagram of a substrate in a manufacturing method of a thin film bulk acoustic resonator according to an embodiment of the present application;
fig. 6 is one of schematic diagrams of a cavity formed on a substrate in a method for manufacturing a thin film bulk acoustic resonator according to an embodiment of the present application;
fig. 7 is a second schematic diagram of forming a cavity on a substrate in a method for manufacturing a film bulk acoustic resonator according to an embodiment of the present application;
fig. 8 is one of schematic diagrams of depositing a first sacrificial layer in a cavity in a method for manufacturing a thin film bulk acoustic resonator according to an embodiment of the present application;
fig. 9 is a second schematic diagram illustrating a first sacrificial layer deposited in a cavity in a method for manufacturing a thin film bulk acoustic resonator according to an embodiment of the present application;
fig. 10 is one of schematic diagrams of trenches etched in a first sacrificial layer in a method for manufacturing a thin film bulk acoustic resonator according to an embodiment of the present application;
fig. 11 is a second schematic diagram of a trench etched in the first sacrificial layer in the method for manufacturing a film bulk acoustic resonator according to the embodiment of the present application;
fig. 12 is a schematic diagram of forming a bottom electrode on a substrate in a method for manufacturing a thin film bulk acoustic resonator according to an embodiment of the present application;
fig. 13 is a second schematic diagram of forming a bottom electrode on a substrate in a method for manufacturing a thin film bulk acoustic resonator according to an embodiment of the present application;
fig. 14 is one of schematic diagrams of depositing a second sacrificial layer on a bottom electrode in a method for manufacturing a thin film bulk acoustic resonator according to an embodiment of the present application;
fig. 15 is a second schematic diagram illustrating a second sacrificial layer deposited on the bottom electrode in the method for manufacturing a thin film bulk acoustic resonator according to the embodiment of the present application;
fig. 16 is a schematic view of a piezoelectric layer formed on a bottom electrode in a method for manufacturing a thin film bulk acoustic resonator according to an embodiment of the present application;
fig. 17 is a second schematic diagram of forming a piezoelectric layer on a bottom electrode in the method for manufacturing a thin film bulk acoustic resonator according to the embodiment of the present application;
fig. 18 is a schematic diagram of forming a top electrode on a piezoelectric layer in a method for manufacturing a thin film bulk acoustic resonator according to an embodiment of the present application;
fig. 19 is a second schematic diagram illustrating a top electrode formed on a piezoelectric layer in a method for manufacturing a thin film bulk acoustic resonator according to an embodiment of the present application;
fig. 20 is one of schematic diagrams of forming a first groove and a first air bridge in a method for manufacturing a thin film bulk acoustic resonator according to an embodiment of the present application;
fig. 21 is a second schematic diagram of forming a first groove and a first air bridge in the method for manufacturing a thin film bulk acoustic resonator according to the embodiment of the present application.
Icon: 1-a substrate; 2-a piezoelectric layer; 3-a top electrode; 4-a first groove; 5-a bottom electrode; 6-a cavity; 7-a first air bridge; 8-a second groove; 9-a second air bridge; 10-a release hole; 11-a first sacrificial layer; 12-a trench; 13-second sacrificial layer.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application.
In the description of the present application, it should be noted that the terms "inside", "outside", and the like indicate orientations or positional relationships based on orientations or positional relationships shown in the drawings or orientations or positional relationships that the product of the application is usually placed in when used, and are used only for convenience of description and simplification of the description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed in a specific orientation, and operate, and thus, should not be construed as limiting the present application. Furthermore, the terms "first," "second," and the like are used solely to distinguish one from another, and are not to be construed as indicating or implying relative importance.
It should also be noted that, unless expressly stated or limited otherwise, the terms "disposed" and "connected" are to be construed broadly and include, for example, fixed and removable connections as well as integral connections; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in this application will be understood to be a specific case for those of ordinary skill in the art.
In the existing film bulk acoustic resonator, the transverse acoustic wave leakage is reduced by designing a corresponding structure on an electrode, and the acoustic wave leakage passing through an electrode part can be reflected to the maximum extent by designing a structure for reflecting the acoustic wave on the electrode so as to solve the problem of acoustic wave energy leakage. However, the reflection efficiency of the piezoelectric material is greatly reduced due to the leakage of the sound wave from the inside of the piezoelectric material, and the sound wave inside the piezoelectric material cannot be reflected well.
To solve the above problem, referring to fig. 1, an embodiment of the present invention provides a film bulk acoustic resonator, which includes a substrate 1, a bottom electrode 5, a piezoelectric layer 2, and a top electrode 3 sequentially stacked on the substrate 1, a cavity 6 formed between the substrate 1 and the bottom electrode 5, an effective area formed by overlapping projection areas of the bottom electrode 5, the piezoelectric layer 2, and the top electrode 3 on the substrate 1, a first air bridge 7 formed between the bottom electrode 5 and the piezoelectric layer 2, a first groove 4 formed on the piezoelectric layer 2 outside the effective area, the first groove 4 located on a side of the piezoelectric layer 2 away from the bottom electrode 5, and the first groove 4 and the first air bridge 7 correspondingly arranged in a projection direction.
The bottom electrode 5, the piezoelectric layer 2 and the top electrode 3 are stacked on the substrate 1, and in the transverse direction in fig. 1, the piezoelectric layer 2 completely covers the substrate 1, and the bottom electrode 5 and the top electrode 3 do not completely cover the substrate 1, so that an effective area is formed in an area where projections of the bottom electrode 5, the piezoelectric layer 2 and the top electrode 3 on the substrate 1 respectively coincide, and accordingly, an area outside the effective area is a non-effective area, in other words, an area where projections of the bottom electrode 5, the piezoelectric layer 2 and the top electrode 3 on the substrate 1 do not coincide is a non-effective area.
The substrate 1 is provided with a cavity 6, the cavity 6 is positioned on one side of the substrate 1 close to the bottom electrode 5, a first air bridge 7 is formed between the bottom electrode 5 and the piezoelectric layer 2, and the bridge surface of the first air bridge 7 arches towards the cavity 6. And outside the active area, namely in the inactive area, the piezoelectric layer 2 is formed with a first groove 4 corresponding to the first air bridge 7 in the projection direction, the notch of the first groove 4 faces the side away from the bottom electrode 5, and the top electrode 3 is not covered to the notch position of the first groove 4, so that the notch of the first groove 4 is exposed.
Through forming first recess 4 on the piezoelectric layer 2 of non-active area, block the route that the sound wave transmits to the side, reduce the horizontal sound wave of piezoelectric layer 2 and reveal, form first air bridge 7 in the position department of the first recess 4 that corresponds piezoelectric layer 2 simultaneously, first air bridge 7 can restrict the sound wave energy through bottom electrode 5, and can also make first recess 4 surrounded by the air, the sound wave can be reflected well to the air, reduced the inside sound wave of piezoelectric layer 2 and revealed, further improved the Q value of resonator.
To sum up, according to the film bulk acoustic resonator provided by the embodiment of the present application, the substrate 1 with the cavity 6 is sequentially stacked with the bottom electrode 5, the piezoelectric layer 2 and the top electrode 3, the cavity 6 is located between the substrate 1 and the bottom electrode 5, the piezoelectric layer 2 and the top electrode 3 form an active area in an area where projections on the substrate 1 coincide with each other, outside the active area, the first air bridge 7 is formed between the bottom electrode 5 and the piezoelectric layer 2, the piezoelectric layer 2 is formed with the first groove 4 corresponding to a projection direction of the first air bridge 7, the first groove 4 is located on a side of the piezoelectric layer 2 away from the bottom electrode 5, acoustic energy passing through the bottom electrode 5 is limited by the first air bridge 7, and meanwhile, the first groove 4 is formed on the piezoelectric layer 2 in an inactive area to reduce lateral acoustic wave leakage of the piezoelectric layer 2, so that acoustic energy leakage is sufficiently reduced, and a Q value of the resonator is improved.
As shown in fig. 1, the first recess 4 and the first air bridge 7 are disposed correspondingly, and the first recess 4 does not penetrate through the piezoelectric layer 2, in other words, the first recess 4 and the first air bridge 7 are not communicated; in addition, the axes of the first air bridge 7 and the first groove 4 are collinear; of course, the first air bridge 7 and the first groove 4 may also be slightly offset, which is selected according to actual needs and is not limited to the above.
Further, in another practical implementation manner of the present application, as shown in fig. 2, the first groove 4 is in communication with the first air bridge 7, so that air can enter the first groove 4 to better reflect the acoustic wave and reduce the acoustic wave leakage inside the piezoelectric layer 2.
On the basis, a second air bridge 9 is formed between the top electrode 3 and the piezoelectric layer 2, a second groove 8 is formed on the piezoelectric layer 2 outside the effective area and at a position corresponding to the second air bridge 9 in the projection direction, and the second groove 8 is communicated with the cavity 6.
Illustratively, as shown in fig. 3, a second air bridge 9 is formed between the top electrode 3 and the piezoelectric layer 2, the bridge surface of the second air bridge 9 is arched in a direction away from the piezoelectric layer 2, the projection directions of the second air bridge 9 and the second groove 8 correspond, and the second groove 8 is located in the non-active area. Similar to the first air bridge 7 and the first groove 4, the second groove 8 is formed on the piezoelectric layer 2 in the non-effective area, so that the path of sound waves transmitted to the side edge is blocked, the transverse sound wave leakage of the piezoelectric layer 2 is reduced, meanwhile, the second air bridge 9 arranged corresponding to the second groove 8 limits the sound wave energy passing through the top electrode 3, the second groove 8 is also surrounded by air to reflect the sound waves, the sound wave leakage inside the piezoelectric layer 2 is reduced, and the Q value of the resonator is improved.
Accordingly, as shown in fig. 3, the second groove 8 does not penetrate through the piezoelectric layer 2, and it is also possible that, as shown in fig. 4, the second groove 8 communicates with the second air bridge 9 to better reflect the acoustic wave and reduce the acoustic wave leakage inside the piezoelectric layer 2. The first air bridge 7 and the first groove 4, and the second air bridge 9 and the second groove 8 in the above-mentioned fig. 2, 3 and 4 are all arranged slightly offset, i.e. the axes of the two are not collinear.
In summary, according to the film bulk acoustic resonator provided by the embodiment of the present application, the grooves (the first groove 4 and the second groove 8) are formed by etching the piezoelectric layer 2, and the air bridge is disposed on the electrode layer (the bottom electrode 5 forms the first air bridge 7, and the top electrode 3 forms the second air bridge 9), so that the acoustic energy leakage of the top electrode 3, the bottom electrode 5, and the piezoelectric layer 2 is reduced, and the Q value of the resonator is improved.
On the other hand, an embodiment of the present application further provides a method for manufacturing a thin film bulk acoustic resonator, where the method is used to manufacture the thin film bulk acoustic resonator, and the method includes:
s100: a substrate 1 with a recess formed in one side of the substrate 1 is provided.
As shown in fig. 5, a substrate 1 is provided, the substrate 1 may be a silicon substrate 1; a recess is then etched into the substrate 1 to form the cavity 6, with the recess being located on one side of the substrate 1. As shown in fig. 6 and fig. 7, an etched groove is formed on the substrate 1, and a plurality of release holes 10 are formed around the groove, and the release holes 10 are used for releasing the sacrificial layer subsequently.
S110: forming a bottom electrode 5 on a side of a substrate 1 provided with a groove through which a cavity 6 is formed between the substrate 1 and the bottom electrode 5; a first sacrificial layer 11 is deposited in the groove and the first sacrificial layer 11 is patterned for forming a first air bridge 7, and a bottom electrode 5 covers the substrate 1 and exposes a portion of the substrate 1.
As shown in fig. 8 and 9, after forming the groove in the substrate 1, a first sacrificial layer 11 is deposited in the groove to fill the groove. The first sacrificial layer 11 can be made of silicon dioxide material, the first sacrificial layer 11 is filled in the groove and is diffused to fill the release hole 10; as shown in fig. 10 and 11, a trench 12 for forming the first air bridge 7 is then etched on the first sacrificial layer 11, and as shown in fig. 12 and 13, the bottom electrode 5 is formed on the first sacrificial layer 11, and the bottom electrode 5 is patterned at the trench 12 such that the bottom electrode 5 has a trench 12 pattern matching the trench 12.
The bottom electrode 5 partially covers the substrate 1, the substrate 1 is not completely covered by the bottom electrode 5, and a part of the substrate 1 is exposed.
S120: a piezoelectric layer 2 having a first recess 4 is formed on the patterned bottom electrode 5 such that the piezoelectric layer 2 covers the substrate 1, the first recess 4 being formed on the side facing away from the bottom electrode 5.
As shown in fig. 14 and 15, depositing a second sacrificial layer 13 on the bottom electrode 5 corresponding to the trench 12, so that the second sacrificial layer 13 is flush with the surface of the bottom electrode 5, and the second sacrificial layer 13 fills the trench 12 of the bottom electrode 5; the bottom electrode 5 does not completely cover the substrate 1 and, as shown in fig. 16 and 17, the piezoelectric layer 2 is deposited on the bottom electrode 5 such that the piezoelectric layer 2 completely covers the substrate 1. The second sacrificial layer 13 may also be a silicon dioxide material.
S130: a top electrode 3 is formed on the piezoelectric layer 2 and patterned such that the piezoelectric layer 2 is covered by the top electrode 3 and the area of the piezoelectric layer 2 where the first recess 4 is provided is exposed.
A slant step is formed on the piezoelectric layer 2, so that two planes with height difference are formed on the upper surface of the piezoelectric layer 2; as shown in fig. 18 and 19, the top electrode 3 is formed on the piezoelectric layer 2, and the top electrode 3 is patterned so that the top electrode 3 has a structure corresponding to the inclined steps of the piezoelectric layer 2, and the upper surface of the top electrode 3 also has two planes having a height difference. And the top electrode 3 partially covers the piezoelectric layer 2 to form an active area, and a partial area is exposed as a non-active area for etching the first groove 4.
Then, as shown in fig. 20 and 21, a first groove 4 is etched at the position of the piezoelectric layer 2 corresponding to the trench 12, the first groove 4 is located at the edge of the piezoelectric layer 2 close to the top electrode 3 in the inactive area, and the first sacrificial layer 11 and the second sacrificial layer 13 are released to form the cavity 6 and the first air bridge 7.
The structures of the other three embodiments are similar to each other in the manufacturing method, and therefore, the detailed description is omitted, and those skilled in the art can derive the structures according to the same method.
The preparation method of the film bulk acoustic resonator comprises the same structure and beneficial effects as those of the film bulk acoustic resonator in the previous embodiment. The structure and the advantageous effects of the film bulk acoustic resonator have been described in detail in the foregoing embodiments, and are not described in detail herein.
The above description is only an example of the present application and is not intended to limit the scope of the present application, and various modifications and changes may be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims (10)
1. A thin film bulk acoustic resonator, comprising: the piezoelectric device comprises a substrate, wherein a bottom electrode, a piezoelectric layer and a top electrode are sequentially stacked on the substrate, a cavity is formed between the substrate and the bottom electrode, an effective area is formed in the area where projections of the bottom electrode, the piezoelectric layer and the top electrode are overlapped on the substrate respectively, a first air bridge is formed between the bottom electrode and the piezoelectric layer, a first groove is formed in the piezoelectric layer outside the effective area, the first groove is located on the side, away from the bottom electrode, of the piezoelectric layer, and the first groove and the first air bridge are correspondingly arranged in the projection direction.
2. The film bulk acoustic resonator of claim 1, wherein the first notch is in communication with the first air bridge.
3. The film bulk acoustic resonator according to claim 1, wherein a second air bridge is formed between the top electrode and the piezoelectric layer, and a second recess is formed in the piezoelectric layer outside the active area at a position corresponding to the second air bridge in the projection direction, and the second recess communicates with the cavity.
4. The film bulk acoustic resonator of claim 3, wherein the second notch is in communication with the second air bridge.
5. A method for manufacturing a thin film bulk acoustic resonator, which is used for manufacturing the thin film bulk acoustic resonator according to any one of claims 1 to 4, and comprises the following steps:
providing a substrate with a recess formed in one side of the substrate;
forming a bottom electrode on one side of the substrate, wherein the groove is arranged on the substrate, and forming a cavity between the substrate and the bottom electrode through the groove; depositing a first sacrificial layer in the groove, and patterning the first sacrificial layer to form a first air bridge, wherein the bottom electrode covers the substrate and exposes part of the substrate;
forming a piezoelectric layer with a first groove on the patterned bottom electrode, wherein the piezoelectric layer covers the substrate, and the first groove is formed on the side away from the bottom electrode;
and forming a top electrode on the piezoelectric layer, patterning the top electrode, covering the piezoelectric layer by the top electrode, and exposing the area of the piezoelectric layer, where the first groove is arranged.
6. The method for manufacturing a thin film bulk acoustic resonator according to claim 5, wherein the providing a substrate with a groove formed in one side of the substrate comprises:
providing the substrate;
and etching the substrate to form the groove.
7. The method for manufacturing a thin film bulk acoustic resonator according to claim 5, wherein a bottom electrode is formed on the substrate on a side where the recess is provided, and a cavity is formed between the substrate and the bottom electrode through the recess; depositing a first sacrificial layer in the groove and patterning the first sacrificial layer for forming a first air bridge, wherein the bottom electrode covers the substrate and exposes a portion of the substrate comprises:
etching a groove for forming the first air bridge on the first sacrificial layer;
and forming the bottom electrode on the substrate, wherein the cavity is formed at the groove.
8. The method for manufacturing a thin film bulk acoustic resonator according to claim 7, wherein the forming a piezoelectric layer having a first groove on the patterned bottom electrode such that the piezoelectric layer covers the substrate, the first groove being formed on a side facing away from the bottom electrode includes:
depositing a second sacrificial layer at the position of the bottom electrode corresponding to the groove so as to enable the second sacrificial layer to be flush with the surface of the bottom electrode;
depositing the piezoelectric layer on the bottom electrode.
9. The method of manufacturing the thin film bulk acoustic resonator according to claim 8, wherein the forming and patterning a top electrode on the piezoelectric layer such that the top electrode covers the piezoelectric layer and exposes a region of the piezoelectric layer where the first groove is provided comprises:
forming the top electrode on the piezoelectric layer and patterning the top electrode such that the top electrode partially covers the piezoelectric layer;
and etching the first groove at the position of the exposed piezoelectric layer corresponding to the groove, and simultaneously releasing the first sacrificial layer and the second sacrificial layer to respectively form the cavity and the first air bridge correspondingly.
10. The method of manufacturing a thin film bulk acoustic resonator according to claim 8, wherein the material of the substrate includes silicon, and the material of the first sacrificial layer and the second sacrificial layer includes silicon dioxide.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN202211062831.2A CN115276600B (en) | 2022-09-01 | 2022-09-01 | Film bulk acoustic resonator and preparation method thereof |
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| CN202211062831.2A CN115276600B (en) | 2022-09-01 | 2022-09-01 | Film bulk acoustic resonator and preparation method thereof |
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| CN115276600A true CN115276600A (en) | 2022-11-01 |
| CN115276600B CN115276600B (en) | 2023-12-08 |
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| CN117833859A (en) * | 2024-01-03 | 2024-04-05 | 武汉敏声新技术有限公司 | Resonator and preparation method thereof |
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