CN220798237U - Film bulk acoustic resonator - Google Patents
Film bulk acoustic resonator Download PDFInfo
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- CN220798237U CN220798237U CN202321923213.2U CN202321923213U CN220798237U CN 220798237 U CN220798237 U CN 220798237U CN 202321923213 U CN202321923213 U CN 202321923213U CN 220798237 U CN220798237 U CN 220798237U
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- 239000000758 substrate Substances 0.000 claims abstract description 137
- 239000000725 suspension Substances 0.000 claims abstract description 17
- 239000010409 thin film Substances 0.000 claims description 59
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- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 229910021420 polycrystalline silicon Inorganic materials 0.000 description 4
- 229920005591 polysilicon Polymers 0.000 description 4
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- 229910052581 Si3N4 Inorganic materials 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
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- 235000012239 silicon dioxide Nutrition 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 2
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
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- 229910052738 indium Inorganic materials 0.000 description 1
- APFVFJFRJDLVQX-UHFFFAOYSA-N indium atom Chemical compound [In] APFVFJFRJDLVQX-UHFFFAOYSA-N 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
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- Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)
Abstract
The utility model discloses a film bulk acoustic resonator, which comprises: the first support layer is located in the second edge region and comprises a first support portion and a first suspension portion, the first suspension portion comprises a first concave portion, a first protruding portion and a second concave portion, the first support layer is located in the first edge region and comprises a second protruding portion, the first support portion is in contact with the substrate, the first concave portion, the first protruding portion, the second concave portion and the second protruding portion are not in contact with the substrate, and a cavity is formed in the first surface, adjacent to the first support layer, of the substrate. Or the part of the first supporting layer positioned in the second edge area comprises a second supporting part, the second supporting part is in contact with the substrate, the first supporting layer further comprises a second suspending part positioned between the second supporting part and the first edge area, the second suspending part further comprises at least one third protruding part, and the first edge area comprises a fourth protruding part.
Description
Technical Field
The utility model relates to the technical field of resonators, in particular to a film bulk acoustic resonator.
Background
With the rapid development of 5G communication technology, the application and the requirement of the radio frequency filter are continuously upgraded, the working frequency of the radio frequency filter is higher and higher, the bandwidth is wider and wider, the insertion loss is lower and the performance requirement on the whole radio frequency filter is higher and higher. In order to meet the filter performance requirements at high frequencies, thin Film Bulk Acoustic Resonators (FBARs) are the mainstay of research in the present. Fig. 1 is a schematic structural view of a conventional thin film bulk acoustic resonator, which is connected to a substrate 10 through a bottom electrode 30 and a piezoelectric layer 40, supporting the entire resonance region. The FBAR resonator is a sandwich structure of the top electrode 50-the piezoelectric layer 40-the bottom electrode 30, but the design has limitation, and the FBAR of the prior art has transverse parasitic clutter and leaks, which affects the performance of the thin film bulk acoustic resonator.
Disclosure of utility model
The utility model provides a film bulk acoustic resonator which can effectively solve the problem of outward propagation and leakage of transverse wave energy and improve the Q value of the resonator.
According to an aspect of the present utility model, there is provided a thin film bulk acoustic resonator comprising:
The substrate, the first supporting layer, the bottom electrode, the piezoelectric layer and the top electrode are sequentially stacked;
The resonator comprises a resonance area, a first edge area and a second edge area, wherein the first edge area and the second edge area surround the resonance area; the top electrode is arranged in the resonance area, and the piezoelectric layer and the bottom electrode are arranged in the first edge area and the resonance area; the first supporting layer is arranged in the first edge area and the second edge area;
The part of the first supporting layer located in the second edge area comprises a first supporting part and a first suspending part, the first suspending part comprises a first concave part, a first convex part and a second concave part, the part of the first supporting layer located in the first edge area comprises a second convex part, the first supporting part is in contact with the substrate, the first concave part, the first convex part, the second concave part and the second convex part are not in contact with the substrate, and the first supporting part, the first concave part, the first convex part and the second concave part are sequentially arranged in the direction of pointing to the resonance area in the second edge area; the first surface of the substrate adjacent to the first supporting layer is provided with a cavity, the vertical projection of the resonance area, the first edge area and the second edge area except the first supporting part on the substrate is positioned in the cavity, the distance between the surface of the first concave part and the second concave part adjacent to the substrate and the second surface of the substrate far away from the bottom electrode is smaller than the distance between the surface of the first convex part and the second convex part adjacent to the substrate and the second surface of the substrate, and the bottom electrode is contacted with the surface of the second convex part far away from the substrate;
Or the first surface of the substrate adjacent to the first support layer is a plane, the portion of the first support layer located in the second edge region comprises a second support portion, the second support portion is in contact with the substrate, the first support layer further comprises a second suspension portion located between the second support portion and the first edge region, the second suspension portion further comprises at least one third protruding portion, the first edge region comprises a fourth protruding portion, the distance between the surfaces of the third protruding portion and the fourth protruding portion adjacent to the substrate and the first surface of the substrate is greater than the distance between the surfaces of the other areas of the first support layer adjacent to the substrate and the first surface of the substrate, the bottom electrode is in contact with the surface of the fourth protruding portion away from the substrate, and the second suspension portion of the first support layer is not in contact with the first surface of the substrate.
According to the thin film bulk acoustic resonator provided by the technical scheme of the utility model, the first supporting layer is provided with the first concave part, the first convex part and the second concave part, the first convex part and the second concave part which are arranged on the first supporting layer can reflect transverse acoustic waves propagating along the resonator plane for multiple times, or the second supporting layer, the third convex part and the fourth convex part are arranged on the first supporting layer, and the second supporting layer, the third convex part and the fourth convex part can reflect transverse acoustic waves propagating along the resonator plane for multiple times, so that the problem that vibration energy of the traditional thin film bulk acoustic resonator leaks to a substrate is effectively reduced, and the Q value of the resonator is greatly improved.
It should be understood that the description in this section is not intended to identify key or critical features of the embodiments of the utility model or to delineate the scope of the utility model. Other features of the present utility model will become apparent from the description that follows.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present utility model, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a conventional thin film bulk acoustic resonator;
Fig. 2 is a schematic structural diagram of a thin film bulk acoustic resonator according to a first embodiment of the present utility model;
FIG. 3 is a schematic diagram of a thin film bulk acoustic resonator according to a first embodiment of the present utility model;
FIG. 4 is a graph of vibration displacement of a conventional thin film bulk acoustic resonator;
FIG. 5 is a graph of vibration displacement of the thin film bulk acoustic resonator of FIG. 2;
FIG. 6 is a schematic diagram of a structure of a thin film bulk acoustic resonator according to a first embodiment of the present utility model;
FIG. 7 is a schematic diagram of a structure of a thin film bulk acoustic resonator according to a first embodiment of the present utility model;
FIG. 8 is a schematic diagram of a structure of a thin film bulk acoustic resonator according to a first embodiment of the present utility model;
FIG. 9 is a schematic diagram of a structure of a thin film bulk acoustic resonator according to a first embodiment of the present utility model;
FIG. 10 is a schematic diagram of a structure of a thin film bulk acoustic resonator according to a first embodiment of the present utility model;
FIG. 11 is a schematic diagram of a structure of a thin film bulk acoustic resonator according to a first embodiment of the present utility model;
FIG. 12 is a flowchart of a method for fabricating a thin film bulk acoustic resonator according to a second embodiment of the present utility model;
Fig. 13 is a schematic diagram of a cavity structure of a thin film bulk acoustic resonator according to a second embodiment of the present utility model;
Fig. 14 is a schematic diagram of a preparation process of a thin film bulk acoustic resonator according to a second embodiment of the present utility model;
fig. 15 is a schematic view of a manufacturing process of a thin film bulk acoustic resonator according to a second embodiment of the present utility model;
fig. 16 is a schematic view of a manufacturing process of a thin film bulk acoustic resonator according to a second embodiment of the present utility model;
FIG. 17 is a schematic diagram of a manufacturing process of a thin film bulk acoustic resonator according to a second embodiment of the present utility model;
Fig. 18 is a schematic diagram of a preparation process of a thin film bulk acoustic resonator according to a second embodiment of the present utility model;
FIG. 19 is a flowchart of a method for fabricating a thin film bulk acoustic resonator according to a second embodiment of the present utility model;
FIG. 20 is a schematic diagram of a sacrificial layer structure of a thin film bulk acoustic resonator according to a second embodiment of the present utility model;
FIG. 21 is a flowchart of a method for fabricating a thin film bulk acoustic resonator according to a second embodiment of the present utility model;
FIG. 22 is a flowchart of a method for fabricating a thin film bulk acoustic resonator according to a second embodiment of the present utility model;
FIG. 23 is a flowchart of a method for fabricating a thin film bulk acoustic resonator according to a second embodiment of the present utility model;
Fig. 24 is a flowchart of a method for manufacturing a thin film bulk acoustic resonator according to a second embodiment of the present utility model.
Detailed Description
In order that those skilled in the art will better understand the present utility model, a technical solution in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present utility model, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present utility model without making any inventive effort, shall fall within the scope of the present utility model.
It should be noted that the terms "first," "second," and the like in the description and the claims of the present utility model and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments of the utility model described herein may be implemented in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
Example 1
An embodiment of the present utility model provides a thin film bulk acoustic resonator, and fig. 2 is a schematic structural diagram of a thin film bulk acoustic resonator provided in a first embodiment of the present utility model, and referring to fig. 2, the thin film bulk acoustic resonator includes: the substrate 10, the first support layer 20, the bottom electrode 30, the piezoelectric layer 40, and the top electrode 50 are sequentially stacked.
The resonator comprises a resonance region 60 and a first edge region 70 and a second edge region 80 surrounding the resonance region 60, the second edge region 80 surrounding the first edge region 70; the top electrode 50 is disposed in the resonance region 60, and the piezoelectric layer 40 and the bottom electrode 30 are disposed in the first edge region 70 and the resonance region 60; the first support layer 20 is disposed at least in the first edge region 70 and the second edge region 80.
The portion of the first support layer 20 located in the second edge region 80 includes a first support portion 21 and a first suspension portion, the first suspension portion includes a first recess portion 24, a first protrusion portion 22 and a second recess portion 25, the portion of the first support layer 20 located in the first edge region 70 includes a second protrusion portion 23, the first support portion 21 is in contact with the substrate 10, the first recess portion 24, the first protrusion portion 22, the second recess portion 25 and the second protrusion portion 23 are not in contact with the substrate, and the first support portion 21, the first recess portion 24, the first protrusion portion 22 and the second recess portion 25 are sequentially disposed in a direction in which the second edge region 80 points to the resonance region 60; the substrate 10 has a cavity adjacent to the first surface of the first support layer 20, the vertical projection of the resonance region 60, the first edge region 70 and the second edge region 80 other than the first support portion 21 into the cavity, the distance between the surface of the first recess 24 and the second recess 25 adjacent to the substrate 10 and the second surface of the substrate 10 remote from the bottom electrode 30 is smaller than the distance between the surface of the first protrusion 22 and the second protrusion 23 adjacent to the substrate 10 and the second surface of the substrate 10, and the surface of the bottom electrode 30 and the second protrusion 23 remote from the substrate 10 are in contact.
Or fig. 3 is a schematic structural diagram of a thin film bulk acoustic resonator according to a first embodiment of the present utility model, referring to fig. 3, a first surface of a substrate 10 adjacent to a first supporting layer 20 is planar, a portion of the first supporting layer 20 located at a second edge region 80 includes a second supporting portion 26, the second supporting portion 26 contacts the substrate 10, the first supporting layer 20 further includes a second suspending portion located between the second supporting portion 26 and the first edge region 70, the second suspending portion further includes at least one third protruding portion 27, the first edge region 70 includes a fourth protruding portion 28, a distance between a surface of the third protruding portion 27 and the fourth protruding portion 28 adjacent to the substrate 10 and the first surface of the substrate 10 is greater than a distance between a surface of the other region of the second suspending portion adjacent to the substrate 10 and the first surface of the substrate 10, the bottom electrode 30 contacts the surface of the fourth protruding portion 28 away from the substrate 10, and the second suspending portion of the first supporting layer 20 does not contact the first surface of the substrate 10.
Specifically, the thin film bulk acoustic resonator in fig. 3 forms a cavity by adopting a new process, so that the stress concentration area formed at the edge of the traditional cavity can be effectively avoided, the stability of the whole structure of the device is poor, and the reliability of the device is greatly improved.
Wherein, the material of the substrate 10 may be glass, alumina (Al 2O3) or high-resistance silicon, which can prevent the electric leakage or interference of the bottom electrode 30; the materials of the bottom electrode 30 and the top electrode 50 may be metal materials, and may be molybdenum as an example; the first support layer 20 may isolate the resonance region 60 formed by the sandwich structure of the top electrode 50-piezoelectric layer 40-bottom electrode 30 from the substrate 10 to form a suspension structure.
The thin film bulk acoustic resonator operates on the principle that when an alternating voltage is applied to the bottom electrode 30 and the top electrode 50 of the resonator, the piezoelectric layer 40 generates an inverse piezoelectric effect, and in this process, the piezoelectric layer 40 contracts and expands and deforms according to the change of the alternating electric field, and this periodic deformation forms periodic vibration, which excites bulk acoustic waves, and when the frequency of the excited bulk acoustic waves is the same as the resonance frequency of the resonance region 60 determined by the total thickness of the bottom electrode 30, the piezoelectric layer 40 and the top electrode 50, resonance is formed. Fig. 4 is a diagram of vibration displacement of a conventional thin film bulk acoustic resonator, referring to fig. 4, in which the abscissa is a position and the ordinate is a displacement, and fig. 4 shows the magnitude of vibration displacement of the resonator at different positions, and by way of example, the leftmost position of the resonator is set to 0 μm, and the abscissa is 50 μm to be a position 50 μm from the leftmost position of the resonator, it can be seen that the conventional thin film bulk acoustic resonator has significant energy leakage at the black circle substrate at the resonance frequency of 2.4GHz, so that the substrate generates significant vibration displacement. Fig. 5 is a vibration displacement diagram of a thin film bulk acoustic resonator in fig. 2, and referring to fig. 5, it can be seen that no obvious energy leakage is seen at the black circle substrate by using the thin film bulk acoustic resonator in the embodiment of the present utility model. The Q value is an important index for evaluating the performance of the resonator, and the conventional FBAR resonator suffers from interference of transverse parasitic clutter on the electrical characteristics of the resonator, so that the Q value of the FBAR resonator is reduced, and the quality of the high-frequency FBAR resonator is greatly affected.
According to the thin film bulk acoustic resonator provided by the embodiment of the utility model, the first supporting layer 20 is arranged in the second edge area 80, the first concave part 24, the first convex part 22 and the second concave part 25 are arranged on the first supporting layer 20, the first concave part 24, the first convex part 22 and the second concave part 25 arranged on the first supporting layer 20 can reflect transverse sound waves propagating along the resonator plane for multiple times, or the second supporting part 26, the third convex part 27 and the fourth convex part 28 are arranged on the first supporting layer 20, and the second supporting part 26, the third convex part 27 and the fourth convex part 28 can reflect transverse sound waves propagating along the resonator plane for multiple times, so that the problem that vibration energy of the traditional thin film bulk acoustic resonator leaks to the substrate 10 is effectively reduced, and the Q value of the resonator is greatly improved.
Alternatively, referring to fig. 2, the distances between the surfaces of the first concave portion 24 and the second concave portion 25 adjacent to the substrate 10 and the second surface of the substrate 10 are the same, and the distances between the surfaces of the first convex portion 22, the second convex portion 23, and the first supporting portion 21 adjacent to the substrate 10 and the second surface of the substrate 10 are the same; referring to fig. 3, the distances between the third and fourth protrusions 27 and 28 and the first surface of the substrate 10 are the same.
Wherein the distances between the surfaces of the first concave portion 24 and the second concave portion 25 adjacent to the substrate and the second surface of the substrate 10 are S1, the distances between the surfaces of the second convex portion 23 and the first supporting portion 21 adjacent to the substrate and the second surface of the substrate 10 are S2, and the distances between the third convex portion 27 and the fourth convex portion 28 and the first surface of the substrate 10 are S3; in the formation process of the first support layer 20, it is necessary to provide a first sacrificial layer on the substrate 10, and the first recess 24 and the second recess 25 are formed therein by etching the first recess and the second recess of the same depth on the first sacrificial layer.
The distances between the surfaces of the first concave portion 24 and the second concave portion 25 adjacent to the substrate 10 and the second surface of the substrate 10, the distances between the surfaces of the first convex portion 22, the second convex portion 23, and the first support portion 21 adjacent to the substrate 10 and the second surface of the substrate 10 are each determined by the size of the first sacrificial layer, the distances between the first concave portion 24 and the second concave portion 25 and the second surface of the substrate 10 are the same, and the distances between the first convex portion 22, the second convex portion 23, and the first support portion 21 and the second surface of the substrate 10 are the same; the distances between the third and fourth protrusions 27 and 28 and the first surface of the substrate 10 are the same, so that the manufacturing process of the first sacrificial layer is simpler.
Optionally, fig. 6 is a schematic structural diagram of yet another film bulk acoustic resonator according to the first embodiment of the present utility model, and referring to fig. 6, the first supporting layer 20 is further disposed in a part of the resonance region 60; the second projection 23 extends to the resonance region; fig. 7 is a schematic structural diagram of yet another film bulk acoustic resonator according to a first embodiment of the present utility model, and referring to fig. 7, the fourth protrusion 28 extends to the resonance region 60.
The first supporting layer 20 may be disposed in the first edge region 70, the second edge region 80, and the resonance region 60 in a region not exceeding 3 μm, and the second protruding portion 23 and the fourth protruding portion 28 are disposed in the first edge region 70, the second edge region 80, and the resonance region 60 in a region not exceeding 3 μm, so that the contact area between the first supporting layer and the bottom electrode may be increased without affecting the performance of the thin film bulk acoustic resonator, and the supporting performance may be enhanced.
Optionally, fig. 8 is a schematic structural diagram of yet another film bulk acoustic resonator according to the first embodiment of the present utility model, and referring to fig. 8, a second supporting layer 91 is further included between the first recess 24 and the substrate 10; fig. 9 is a schematic structural diagram of yet another thin film bulk acoustic resonator according to a first embodiment of the present utility model, and referring to fig. 9, the first supporting layer 20 further includes a third supporting portion located on a side of the second supporting portion 26 away from the resonance region 60, and a third supporting layer 92 is disposed between the third supporting portion and the substrate 10.
Specifically, referring to fig. 8, a first sacrificial layer may be disposed in the cavity, and the first support layer 20, the bottom electrode 30, the piezoelectric layer 40, and the top electrode 50 may be formed on the first sacrificial layer, and then the first sacrificial layer is removed, and since the lateral size of the device is sufficiently large, the first sacrificial layer between the first recess 24 and the substrate 10, that is, the second support layer 91, may not be removed by controlling the etching time.
Referring to fig. 9, a third sacrificial layer may be disposed on the first surface of the substrate 10, and the first support layer 20, the bottom electrode 30, the piezoelectric layer 40, and the top electrode 50 may be formed on the third sacrificial layer, and then the third sacrificial layer may be removed, and the third sacrificial layer between the third support portion and the substrate 10, that is, the third support layer 92, may not be removed, and the support strength may be increased.
Alternatively, referring to fig. 8, the first support layer 20 has a thickness of 0.2-0.8 μm; the distance between the surface of the first projection 22 and the second projection 23 adjacent to the substrate 10 and the bottom surface of the cavity is 2-3 μm; the depth of the first recess 24 and the second recess 25 is 0.6-1.5 μm; referring to fig. 9, the distance between the surface of the third and fourth protrusions 27 and 28 adjacent to the substrate 10 and the first surface of the substrate 10 is 2-3 μm; the depth of the third projection 27 is 0.6-1.5 μm.
Wherein, referring to fig. 8, the distances between the first and second protrusions 22 and 23 and the bottom surface of the cavity are S4, and S4 is 2-3 μm. The depth of the first recess 24 and the second recess 25 is S5, and S5 is 0.6-1.5 μm. The width of the first recess 24 and the second recess 25 in the direction of the resonance region 60 toward the second edge region 80 is S6, and S4, S5 and S6 are each determined by the size of the first sacrificial layer. A first sacrificial layer may be disposed on the substrate 10, the first support layer 20 is formed on the first sacrificial layer, the thickness of the first sacrificial layer is 2-3 μm as same as S4, the first recess and the second recess are etched on the first sacrificial layer, the first recess 24 and the second recess 25 are respectively formed in the first recess and the second recess, the depth of the first recess and the second recess is 0.6-1.5 μm as same as the depth S5 of the first recess 24 and the second recess 25, and the width of the first recess and the second recess is 10-15 μm. The first supporting layer adopts the size, so that the part of the first supporting layer located in the second edge area can better reflect transverse sound waves, and the preparation process is simpler.
Referring to fig. 9, the distance between the third and fourth protrusions 27 and 28 and the first surface of the substrate 10 is S3, the depth of the third protrusion 27 is S7, the distance between the adjacent sides of the third and fourth protrusions 27 and 28 is S8, and the width of the second support 26 is S9 in a direction along the resonance region 60 toward the second edge region 80, and the S3, S7, S8, and S9 are each determined by the size of the third sacrificial layer. A third sacrificial layer may be provided on the substrate 10, the first support layer 20 may be formed on the third sacrificial layer, and third, fourth and fifth grooves may be formed on the third sacrificial layer, the distances between the third and fourth protrusions 27 and 28 and the first surface of the substrate 10 being the same as 2-3 μm; the depth of the fourth groove and the fifth groove is 0.6-1.5 μm as the depth of the third protrusion 27; the width of the fourth groove is 5-10 mu m; the width of the third groove is 5-10 μm in the direction in which the resonance region 60 points to the second edge region 80, and the width of the second support 26 is smaller than the width of the third groove. The first supporting layer is arranged in the size, so that the part of the first supporting layer, which is positioned in the second edge area, can better reflect transverse sound waves, and the preparation process is simpler.
Alternatively, fig. 10 is a schematic structural diagram of still another film bulk acoustic resonator according to the first embodiment of the present utility model, and referring to fig. 10, the first protrusion 22 is provided with a first release hole 291, and the first release hole 291 penetrates the first support layer 20; fig. 9 is a schematic structural diagram of yet another film bulk acoustic resonator according to the first embodiment of the present utility model, and referring to fig. 9, the third protrusion 27 is provided with a second release hole 292, and the second release hole 292 penetrates the first support layer 20; the aperture of the first and second release holes 291 and 292 is 10 μm.
Wherein, since a sacrificial layer is required to be disposed on the first surface of the substrate 10 and the first support layer 20, the bottom electrode 30, the piezoelectric layer 40 and the top electrode 50 are formed on the sacrificial layer in the resonator structure forming process, the sacrificial layer may be removed by etching the first release hole 291 formed by the first support layer 20 or the second release hole 292 formed by etching the third protrusion 27, and a cavity may be formed between the substrate 10 and the first support layer 20 after the sacrificial layer is removed.
Optionally, the material of the piezoelectric layer includes at least one of a polycrystalline or monocrystalline material of AlN, alScN, liNbO and LiTaO3, and a ferroelectric monocrystalline material; the material of the first supporting layer is polysilicon or silicon nitride.
Wherein, alN, alScN, liNbO and LiTaO3 are polycrystalline or monocrystalline materials, the piezoelectric performance is better, the process is mature, and In order to improve that the electromechanical coupling coefficient of the traditional piezoelectric layer material can not meet the requirement of larger bandwidth, the piezoelectric layer can also adopt ferroelectric monocrystal with high piezoelectric coefficient, and for example, a solid solution (PMN-PT monocrystal) with a composite perovskite structure doped with indium (In) can be adopted. The first supporting layer is made of polysilicon or silicon nitride, the thin film bulk acoustic resonator structure can be supported on the substrate, and the first supporting layer or the bottom electrode can be used for electric signal transmission.
Example two
The embodiment of the present utility model provides a method for preparing a film bulk acoustic resonator based on the above embodiment, and fig. 12 is a flowchart of a method for preparing a film bulk acoustic resonator according to a second embodiment of the present utility model, and referring to fig. 12, the method includes:
Step 110, providing a substrate; the resonator includes a resonance region and a first edge region surrounding the resonance region and a second edge region surrounding the first edge region.
The substrate material may be glass, alumina (Al 2O3) or high-resistance silicon, among others.
Step 120, forming a cavity on the substrate.
Fig. 13 is a schematic diagram of a cavity structure of a thin film bulk acoustic resonator according to a second embodiment of the present utility model; referring to fig. 13, the substrate 10 may be pattern etched by an etching process to form a cavity 11 having a depth of 2-3 μm.
130, Arranging a first sacrificial layer in the cavity, and forming a first groove and a second groove on the first sacrificial layer; the first groove and the second groove are located in the second edge area, the first groove is arranged on one side, away from the resonance area, of the second groove, and the depth of the first groove and the depth of the second groove are smaller than the thickness of the first sacrificial layer.
Fig. 14 is a schematic diagram of a process for fabricating a thin film bulk acoustic resonator according to a second embodiment of the present utility model, and referring to fig. 14, a first sacrificial layer 12 is formed by performing a deposition process in a cavity, and by way of example, silicon dioxide deposition may be performed, and then Chemical Mechanical Polishing (CMP) grinding is performed on the entire wafer surface, wherein only the first sacrificial layer 12 in the cavity is remained, and the upper surface of the first sacrificial layer 12 in the cavity is flush with the upper surface of the substrate 10; fig. 15 is a schematic view of a manufacturing process of a thin film bulk acoustic resonator according to a second embodiment of the present utility model, and referring to fig. 15, the first sacrificial layer 12 in the cavity is patterned and etched to form a first groove 13 and a second groove 14.
Step 140, forming a first supporting layer on the first sacrificial layer; the first supporting layer is arranged in the first edge area and the second edge area; the first support layer is located in the second edge area, the first suspension part comprises a first concave part, a first convex part and a second concave part, the first support layer is located in the first edge area and comprises a second convex part, the first concave part is located in the first groove, the second concave part is located in the second groove, the first support layer is in contact with the substrate, the first concave part, the first convex part, the second concave part and the second convex part are not in contact with the substrate, and the first support part, the first concave part, the first convex part and the second concave part are sequentially arranged in the direction of the second edge area pointing to the resonance area. Fig. 16 is a schematic view of a manufacturing process of a thin film bulk acoustic resonator according to a second embodiment of the present utility model, and referring to fig. 16, a supporting layer is deposited on a surface of the first sacrificial layer 12, and the supporting layer 20 may be, for example, polysilicon; the support layer deposited on the surface of the first sacrificial layer 12 is subjected to pattern etching, and part or all of the support layer in the resonance region is etched away to form a first support layer 20.
Step 150, forming a second sacrificial layer on the first supporting layer; wherein the second sacrificial layer covers the first sacrificial layer uncovered by the first support layer.
Fig. 17 is a schematic diagram of a process for fabricating a thin film bulk acoustic resonator according to a second embodiment of the present utility model, referring to fig. 17, a second sacrificial layer 15 is deposited on a first supporting layer 20, the thickness of the deposited second sacrificial layer 15 is consistent with that of the first supporting layer 20, the second sacrificial layer 15 is subjected to pattern etching, the second sacrificial layer 15 covered on the first supporting layer 20 is etched, and then the second sacrificial layer 15 is subjected to CMP planarization, so that the upper surface of the second sacrificial layer 15 is flush with the upper surface of the first supporting layer 20.
Step 160, sequentially forming a bottom electrode, a piezoelectric layer and a top electrode on the second sacrificial layer; the top electrode is arranged in the resonance area, the piezoelectric layer and the bottom electrode are arranged in the first edge area and the resonance area, and the bottom electrode is contacted with the surface of the second protruding part far away from the substrate; the distance between the surface of the first recess and the second recess adjacent to the substrate and the second surface of the substrate remote from the bottom electrode is smaller than the distance between the surface of the first projection and the second projection adjacent to the substrate and the second surface of the substrate.
Fig. 18 is a schematic diagram of a manufacturing process of a thin film bulk acoustic resonator according to a second embodiment of the present utility model, and referring to fig. 18, a first electrode layer is formed in a resonance region and a first edge region; removing the first electrode layer at one side of the second edge region to form a bottom electrode 30; forming a piezoelectric layer 40 on the surface of the bottom electrode 30; forming a second electrode layer on the surface of the piezoelectric layer 40; the second electrode layer of the first edge region is removed to form the top electrode 50.
Step 170, removing the first sacrificial layer and the second sacrificial layer.
In which, referring to fig. 10, 12-18, the first and second sacrificial layers 12 and 15 may be removed through the first release holes 291. A solution that can corrode the first sacrificial layer 12 and the second sacrificial layer 15 is poured from the first release hole 291 so that the first sacrificial layer 12 and the second sacrificial layer 15 are removed to form the cavity 11, and the first sacrificial layer 12 located between the first recess and the substrate 10 is left to form the second supporting layer 91 for enhancing the stability of the overall structure.
The embodiment of the present utility model further provides a method for preparing a thin film bulk acoustic resonator based on the above embodiment, and fig. 19 is a flowchart of a method for preparing a thin film bulk acoustic resonator according to a second embodiment of the present utility model, and referring to fig. 19, the method includes:
Step 210, providing a substrate; the resonator includes a resonance region and a first edge region surrounding the resonance region and a second edge region surrounding the first edge region.
Wherein the implementation and benefits of step 210 are the same as step 110.
Step 220, disposing a third sacrificial layer on the first surface of the substrate, and forming a third groove, a fourth groove and a fifth groove on the third sacrificial layer; the third groove, the fourth groove and the fifth groove are located in the second edge area, the third groove and the fifth groove are arranged on one side, far away from the resonance area, of the fourth groove, vertical projection of the fifth groove on the substrate covers vertical projection of the third groove on the substrate, the third groove penetrates through the third sacrificial layer, and the depth of the fourth groove and the depth of the fifth groove are smaller than the thickness of the sacrificial layer.
Fig. 20 is a schematic diagram of a sacrificial layer structure of a thin film bulk acoustic resonator according to a second embodiment of the present utility model, and referring to fig. 20, a third sacrificial layer 16 is deposited on a substrate 10, and exemplary, the third sacrificial layer 16 may be a silicon dioxide sacrificial layer, and an etching pattern is performed on the third sacrificial layer 16 to form a third groove 17; fig. 21 is a flowchart of a method for manufacturing a thin film bulk acoustic resonator according to a second embodiment of the present utility model, and referring to fig. 21, the third sacrificial layer 16 is subjected to a second pattern etching to form a fourth groove 18 and a fifth groove 19.
Step 230, forming a first supporting layer on the surface of the third sacrificial layer; the first supporting layer is arranged in the first edge area and the second edge area; the first support layer is positioned in the third groove, the second support layer is in contact with the substrate, the first support layer further comprises a second suspension part positioned between the second support layer and the first edge region, the second suspension part further comprises at least one third protruding part, the first edge region comprises a fourth protruding part, the third protruding part is positioned between the fifth groove and the fourth groove, the distance between the surfaces of the third protruding part and the fourth protruding part adjacent to the substrate and the first surface of the substrate is larger than the distance between the surfaces of the other areas of the second suspension part adjacent to the substrate and the first surface of the substrate, and the second suspension part of the first support layer is not in contact with the first surface of the substrate.
Fig. 22 is a flowchart of a method for manufacturing a thin film bulk acoustic resonator according to a second embodiment of the present utility model, and referring to fig. 22, a supporting layer may be formed on the surface of the third sacrificial layer 16 by a deposition process, and an exemplary method may be to perform polysilicon deposition to form a supporting layer, and perform pattern etching on the supporting layer to etch away the supporting layer in the resonant region, thereby forming the first supporting layer 20.
Step 240, forming a fourth sacrificial layer on the first supporting layer; wherein the fourth sacrificial layer covers the third sacrificial layer uncovered by the first support layer.
Fig. 23 is a flowchart of a method for manufacturing a thin film bulk acoustic resonator according to a second embodiment of the present utility model, and referring to fig. 23, a fourth sacrificial layer 161 is deposited on the first supporting layer, the thickness of the deposited fourth sacrificial layer 161 is consistent with that of the first supporting layer 20, the fourth sacrificial layer 161 is subjected to pattern etching, the fourth sacrificial layer 161 covered on the first supporting layer 20 is etched, and CMP planarization is performed on the fourth sacrificial layer 161, so that the upper surface of the fourth sacrificial layer 161 is flush with the upper surface of the first supporting layer 20.
Step 250, sequentially forming a bottom electrode, a piezoelectric layer and a top electrode on the fourth sacrificial layer; the top electrode is arranged in the resonance area, the piezoelectric layer and the bottom electrode are arranged in the first edge area and the resonance area, and the bottom electrode is contacted with the surface of the fourth protruding part far away from the substrate.
Fig. 24 is a flowchart of a method for manufacturing a thin film bulk acoustic resonator according to a second embodiment of the present utility model, where, referring to fig. 24, a first electrode layer is formed in a resonance region and a first edge region; removing the first electrode layer at one side of the second edge region to form a bottom electrode 30; forming a piezoelectric layer 40 on the surface of the bottom electrode 30; forming a second electrode layer on the surface of the piezoelectric layer 40; the second electrode layer of the first edge region is removed to form the top electrode 50.
Step 260, removing the third sacrificial layer and the fourth sacrificial layer.
In which, referring to fig. 11, 20-24, the third sacrificial layer 16 and the fourth sacrificial layer 161 may be removed through the second release holes 292. A solution that can corrode the third sacrificial layer 16 and the fourth sacrificial layer 161 is poured from the second release hole 292 so that the third sacrificial layer 16 and the fourth sacrificial layer 161 are removed to form a cavity, and the third sacrificial layer 16 between the third support portion in the first support layer 20 and the substrate 10 is left to form the third support layer 92 for enhancing the stability of the overall structure.
Alternatively, referring to fig. 20 and fig. 21, disposing the third sacrificial layer 16 on the first surface of the substrate 10 includes: depositing a third sacrificial layer 16 on the substrate 10; etching the third sacrificial layer 16 to form a third groove 17, wherein the depth of the third groove 17 is equal to the thickness of the third sacrificial layer 16; performing secondary etching on the third sacrificial layer 16 to form a fourth groove 18 and a fifth groove 19, wherein the depth of the fourth groove 18 and the fifth groove 19 is smaller than the thickness of the third sacrificial layer 16, and the depth of the fourth groove 18 and the depth of the fifth groove 19 are the same; the vertical projection of the fifth groove 19 on the substrate 10 covers the vertical projection of the third groove 17 on the substrate 10, and the width of the fifth groove 19 is larger than the width of the third groove 16 in the direction in which the second edge region points to the resonance region.
The third groove 17, the fourth groove 18 and the fifth groove 19 are etched on the third sacrificial layer 16 to help the subsequent first supporting layer 20 to form the second supporting portion 26, the third protruding portion 27 and the fourth protruding portion 28, so that the transverse sound wave propagating along the resonator plane can be reflected for multiple times, the problem that vibration energy of the traditional film bulk acoustic resonator leaks to the substrate 10 can be effectively reduced, and the Q value of the resonator is greatly improved.
It should be appreciated that various forms of the flows shown above may be used to reorder, add, or delete steps. For example, the steps described in the present utility model may be performed in parallel, sequentially, or in a different order, so long as the desired results of the technical solution of the present utility model are achieved, and the present utility model is not limited herein.
The above embodiments do not limit the scope of the present utility model. It will be apparent to those skilled in the art that various modifications, combinations, sub-combinations and alternatives are possible, depending on design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included in the scope of the present utility model.
Claims (6)
1. A thin film bulk acoustic resonator, comprising:
The substrate, the first supporting layer, the bottom electrode, the piezoelectric layer and the top electrode are sequentially stacked;
The resonator comprises a resonance region and a first edge region and a second edge region surrounding the resonance region, wherein the second edge region surrounds the first edge region; the top electrode is arranged in the resonance area, and the piezoelectric layer and the bottom electrode are arranged in the first edge area and the resonance area; the first supporting layer is arranged in the first edge area and the second edge area;
the part of the first supporting layer located in the second edge area comprises a first supporting part and a first suspending part, the first suspending part comprises a first concave part, a first convex part and a second concave part, the part of the first supporting layer located in the first edge area comprises a second convex part, the first supporting part is in contact with the substrate, the first concave part, the first convex part, the second concave part and the second convex part are not in contact with the substrate, and the first supporting part, the first concave part, the first convex part and the second concave part are sequentially arranged in the direction of pointing to the resonance area in the second edge area; a first surface of the substrate adjacent to the first support layer has a cavity, a perpendicular projection of the resonant region, the first edge region, and the second edge region other than the first support within the cavity, a distance between a surface of the substrate adjacent to the first recess and the second recess and a second surface of the substrate remote from the bottom electrode being less than a distance between a surface of the first protrusion and the second protrusion adjacent to the substrate and a second surface of the substrate, the bottom electrode in contact with the second protrusion remote from the surface of the substrate;
Or the first surface of the substrate adjacent to the first support layer is a plane, the portion of the first support layer located in the second edge region comprises a second support portion, the second support portion is in contact with the substrate, the first support layer further comprises a second suspension portion located between the second support portion and the first edge region, the second suspension portion further comprises at least one third protrusion, the first edge region comprises a fourth protrusion, the distance between the surface of the third protrusion and the fourth protrusion adjacent to the substrate and the first surface of the substrate is greater than the distance between the surface of the second suspension portion adjacent to the first surface of the substrate, the bottom electrode is in contact with the fourth protrusion away from the surface of the substrate, and the second suspension portion of the first support layer is not in contact with the first surface of the substrate.
2. The resonator according to claim 1, characterized in that:
The first concave part and the second concave part are adjacent to the surface of the substrate and the second surface of the substrate, and the first convex part, the second convex part and the first supporting part are adjacent to the surface of the substrate and the second surface of the substrate;
the third and fourth protrusions are the same distance from the first surface of the substrate.
3. The resonator according to claim 1, characterized in that:
the first supporting layer is also arranged in part of the resonance region;
The second protruding portion extends to the resonance region;
The fourth protrusion extends to the resonance region.
4. A resonator according to claim 1, characterized in that,
A second supporting layer is further arranged between the first concave part and the substrate;
The first support layer further comprises a third support portion located on one side, far away from the resonance area, of the second support portion, and a third support layer is arranged between the third support portion and the substrate.
5. A resonator according to claim 2, characterized in that,
The thickness of the first supporting layer is 0.2-0.8 mu m;
The distance between the surface of the first protruding part and the second protruding part adjacent to the substrate and the bottom surface of the cavity is 2-3 mu m; the depth of the first concave part and the second concave part is 0.6-1.5 mu m; a direction along the resonance region toward the second edge region;
The distance between the surface of the third protruding part and the fourth protruding part adjacent to the substrate and the first surface of the substrate is 2-3 μm; the depth of the third protrusion is 0.6-1.5 μm.
6. The resonator according to claim 1, characterized in that:
The first bulge is provided with a first release hole, and the first release hole penetrates through the first supporting layer;
the third protruding part is provided with a second release hole, and the second release hole penetrates through the first supporting layer;
the first release hole and the second release hole have a pore diameter of 10 μm.
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Effective date of registration: 20240510 Address after: 214135 China Sensor Network International Innovation Park F2, 200 Linghu Avenue, Xinwu District, Wuxi City, Jiangsu Province Patentee after: SV SENSTECH (WUXI) CO.,LTD. Country or region after: China Address before: 2 / F, building 3, 439 Chunxiao Road, China (Shanghai) pilot Free Trade Zone, Pudong New Area, Shanghai, 201203 Patentee before: Maigan Microelectronics (Shanghai) Co.,Ltd. Country or region before: China |