CN118232869A - Bulk acoustic wave resonator - Google Patents
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- CN118232869A CN118232869A CN202410448479.9A CN202410448479A CN118232869A CN 118232869 A CN118232869 A CN 118232869A CN 202410448479 A CN202410448479 A CN 202410448479A CN 118232869 A CN118232869 A CN 118232869A
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- acoustic wave
- bulk acoustic
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- 230000001629 suppression Effects 0.000 claims abstract description 59
- 230000002401 inhibitory effect Effects 0.000 claims abstract description 49
- 230000000452 restraining effect Effects 0.000 claims abstract description 20
- 230000005764 inhibitory process Effects 0.000 claims abstract description 16
- 239000000758 substrate Substances 0.000 claims description 37
- 239000004020 conductor Substances 0.000 claims description 12
- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 claims description 5
- 239000012212 insulator Substances 0.000 claims description 4
- 230000007423 decrease Effects 0.000 claims description 3
- 230000002829 reductive effect Effects 0.000 abstract description 6
- 238000010586 diagram Methods 0.000 description 17
- 238000000034 method Methods 0.000 description 12
- 239000000463 material Substances 0.000 description 7
- 230000001902 propagating effect Effects 0.000 description 4
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- 238000000151 deposition Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000004891 communication Methods 0.000 description 2
- 230000008878 coupling Effects 0.000 description 2
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- 239000004205 dimethyl polysiloxane Substances 0.000 description 2
- 238000005530 etching Methods 0.000 description 2
- 230000002452 interceptive effect Effects 0.000 description 2
- 238000005498 polishing Methods 0.000 description 2
- 229920000435 poly(dimethylsiloxane) Polymers 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229910000838 Al alloy Inorganic materials 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- CSDREXVUYHZDNP-UHFFFAOYSA-N alumanylidynesilicon Chemical compound [Al].[Si] CSDREXVUYHZDNP-UHFFFAOYSA-N 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 239000003989 dielectric material Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000002360 explosive Substances 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- NRJVMVHUISHHQB-UHFFFAOYSA-N hafnium(4+);disulfide Chemical compound [S-2].[S-2].[Hf+4] NRJVMVHUISHHQB-UHFFFAOYSA-N 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 description 1
- 229910052808 lithium carbonate Inorganic materials 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
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- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 229910021421 monocrystalline silicon Inorganic materials 0.000 description 1
- 238000000059 patterning Methods 0.000 description 1
- 229910021420 polycrystalline silicon Inorganic materials 0.000 description 1
- -1 polydimethylsiloxane Polymers 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
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- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 1
- 229910010271 silicon carbide Inorganic materials 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
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- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
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- Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)
Abstract
The invention discloses a bulk acoustic wave resonator.A resonance signal in the bulk acoustic wave resonator propagates along a vertical direction and vibrates along a second direction; the bulk acoustic wave resonator comprises a first groove suppression structure and a second groove suppression structure which are positioned on two opposite sides of the top electrode; the first groove inhibiting structure, the top electrode and the second groove inhibiting structure are sequentially arranged along a first direction, and the first direction is perpendicular to the second direction; the first groove inhibiting structure and the second groove inhibiting structure both extend along the second direction; the bulk acoustic wave resonator further comprises a first bump inhibition structure and a second bump inhibition structure which are positioned on the same bottom electrode and/or the same top electrode; the first bulge restraining structure and the second bulge restraining structure are positioned at the edges of two non-adjacent sides of the same bottom electrode and/or the same top electrode; the first bump restraint structure and the second bump restraint structure are arranged along a second direction. By adopting the technical scheme, the quality factor can be improved, stray modal interference is reduced, and meanwhile, the power capacity and the mechanical reliability are improved.
Description
Technical Field
The invention relates to the technical field of radio frequency filtering, in particular to a bulk acoustic wave resonator.
Background
The current 5G communication technology has gradually developed and commercialized, and with the explosive growth of mobile data traffic, the development requirement of the future 6G communication technology is more and more strong. The future frequency band of 5G/6G will put forward the demand for high frequency and broadband of the RF filter, but the existing resonator is difficult to meet the current demands of N79, wiFi 6E and other frequency bands and the future frequency band of 6G.
Disclosure of Invention
The invention provides a bulk acoustic wave resonator which can improve the quality factor, reduce the stray modal interference and improve the power capacity and the mechanical stability of the device.
According to an aspect of the present invention, there is provided a bulk acoustic wave resonator comprising, in order from bottom to top: a substrate, a Bragg reflection gate, a bottom electrode, a piezoelectric layer and a top electrode; the vertical projection of the bottom electrode on the plane of the substrate overlaps with the vertical projection of the top electrode on the plane of the substrate; the resonant signal in the bulk acoustic wave resonator propagates along a vertical direction and vibrates along a second direction, and the second direction is parallel to a plane where the substrate is located;
the bulk acoustic wave resonator further comprises a first groove suppression structure and a second groove suppression structure which are positioned on two opposite sides of the top electrode; the first groove inhibiting structure, the top electrode and the second groove inhibiting structure are sequentially arranged along a first direction, the first direction is also parallel to the plane of the substrate, and the first direction is perpendicular to the second direction; the first groove inhibiting structure and the second groove inhibiting structure both extend along the second direction;
The bulk acoustic wave resonator further comprises a first bump inhibition structure and a second bump inhibition structure located on the same bottom electrode and/or the same top electrode; the first protrusion inhibiting structure and the second protrusion inhibiting structure are respectively positioned at the edges of the two non-adjacent sides of the same bottom electrode and/or the same top electrode; the first bump restraint structure and the second bump restraint structure are aligned along the second direction.
Optionally, the bragg reflector grating includes a first low acoustic impedance layer in contact with the bottom electrode and the piezoelectric layer;
the Bragg reflection grating further comprises a second low acoustic impedance layer and a high acoustic impedance layer which are positioned on one side of the first low acoustic impedance layer close to the substrate and are alternately arranged;
the bottom of the first groove suppressing structure and the bottom of the second groove suppressing structure each expose the high acoustic impedance layer in contact with the first low acoustic impedance layer.
Optionally, the first groove inhibiting structure and the second groove inhibiting structure are filled with a heat conducting material; the acoustic impedance of the thermally conductive material is less than the acoustic impedance of the high acoustic impedance layer in the Bragg reflector grating, and the thermally conductive material is an insulator.
Optionally, the first bump inhibition structure and the second bump inhibition structure are both located at a side of the bottom electrode away from the piezoelectric layer; and/or, the first bump inhibition structure and the second bump inhibition structure are both positioned at one side of the top electrode away from the piezoelectric layer;
A third bulge suppression structure and a fourth bulge suppression structure are arranged on one side, away from the piezoelectric layer, of at least part of the film layers in the Bragg reflection grating;
And the vertical projection of the third bulge restraining structure on the plane of the substrate overlaps with the vertical projection of the first bulge restraining structure on the plane of the substrate, and the vertical projection of the fourth bulge restraining structure on the plane of the substrate overlaps with the vertical projection of the second bulge restraining structure on the plane of the substrate.
Optionally, the extending direction of the first protrusion inhibiting structure and the extending direction of the second protrusion inhibiting structure both intersect with the second direction;
At least part of the extending direction of the first protrusion inhibiting structure intersects the first direction, and/or at least part of the extending direction of the second protrusion inhibiting structure intersects the first direction.
Optionally, the first protrusion inhibiting structure comprises a plurality of first sub-protrusion inhibiting structures and/or the second protrusion inhibiting structure comprises a plurality of second sub-protrusion inhibiting structures.
Optionally, the thickness of the same bottom electrode and/or the same top electrode where the first bump suppression structure and the second bump suppression structure are located is D1, the thickness of the first bump suppression structure is D01, and the thickness of the second bump suppression structure is D02;
Wherein 0.8 x D1.ltoreq.D01.ltoreq.1.2 x D1, and/or 0.8 x D1.ltoreq.D02.ltoreq.1.2 x D1.
Optionally, the maximum width of the same bottom electrode and/or the same top electrode in the second direction where the first bump suppression structure and the second bump suppression structure are located is W1, the maximum width of the first bump suppression structure in the second direction is W01, and the maximum width of the second bump suppression structure in the second direction is W02;
wherein 0 < W01 is less than or equal to 0.1 x W1, and/or 0 < W02 is less than or equal to 0.1 x W1.
Optionally, the width of the first protrusion inhibiting structure and/or the second protrusion inhibiting structure along the second direction gradually decreases from the same bottom electrode and/or the same top electrode near the location to the direction away from the same bottom electrode and/or the same top electrode.
Optionally, the piezoelectric layer includes Y-cut lithium niobate of-30 ° to 0 °.
According to the technical scheme, the spurious modes can be effectively restrained and the quality factor is improved by arranging the first groove restraining structure and the second groove restraining structure and the first bulge restraining structure and the second bulge restraining structure which are positioned on the same bottom electrode and/or the same top electrode, so that the bulk acoustic wave resonator with few spurious modes, high resonant frequency and large power capacity is realized, and the bulk acoustic wave resonator has higher performance, so that the requirements of current N79, wiFi 6E and other frequency bands and future 6G frequency bands are met.
It should be understood that the description in this section is not intended to identify key or critical features of the embodiments of the invention or to delineate the scope of the invention. Other features of the present invention will become apparent from the description that follows.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, 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 invention, 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 top view of a bulk acoustic wave resonator according to an embodiment of the present invention;
FIG. 2 is a schematic cross-sectional view taken along the line A-A' in FIG. 1, in accordance with an embodiment of the present invention;
FIG. 3 is a schematic diagram of the frequency response of a bulk acoustic wave resonator with or without a notch suppression structure provided by an embodiment of the present invention;
fig. 4 is a schematic structural diagram of a process for manufacturing a bulk acoustic wave resonator according to an embodiment of the present invention;
FIG. 5 is a schematic structural view of yet another bulk acoustic wave resonator provided by an embodiment of the present invention;
FIG. 6 is a schematic structural diagram of yet another bulk acoustic wave resonator provided by an embodiment of the present invention;
FIG. 7 is a schematic cross-sectional view taken along section B-B' of FIG. 5, in accordance with an embodiment of the present invention;
FIG. 8 is a schematic top view of a bulk acoustic wave resonator according to an embodiment of the present invention;
fig. 9 is a schematic top view of another bulk acoustic wave resonator according to an embodiment of the present invention;
Fig. 10 is a schematic structural diagram of yet another bulk acoustic wave resonator according to an embodiment of the present invention.
Detailed Description
In order that those skilled in the art will better understand the present invention, a technical solution in the embodiments of the present invention 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 invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.
It should be noted that the terms "first," "second," and the like in the description and the claims of the present invention 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 invention 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.
All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without making any inventive effort are intended to fall within the scope of the present invention. The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention.
Fig. 1 is a schematic top view of a bulk acoustic wave resonator according to an embodiment of the present invention, and fig. 2 is a schematic cross-sectional structure along a section A-A' in fig. 1 according to an embodiment of the present invention, and referring to fig. 1 and fig. 2, the bulk acoustic wave resonator sequentially includes, from bottom to top: a substrate 10, a Bragg reflection grating 20, a bottom electrode 42, a piezoelectric layer 30, and a top electrode 41; the vertical projection of the bottom electrode 42 on the plane of the substrate 10 overlaps with the vertical projection of the top electrode 41 on the plane of the substrate 10; wherein the resonant signal in the bulk acoustic wave resonator propagates in a vertical direction and vibrates in a second direction y, which is parallel to the plane of the substrate 10.
The bulk acoustic wave resonator further includes a first groove suppressing structure 501 and a second groove suppressing structure 502 on opposite sides of the top electrode 41; the first recess-suppressing structure 501, the top electrode 41 and the second recess-suppressing structure 502 are sequentially arranged along a first direction x, which is also parallel to a plane on which the substrate 10 is located, and is perpendicular to a second direction y; the first groove inhibiting structure 501 and the second groove inhibiting structure 502 each extend in the second direction y.
The bulk acoustic wave resonator further comprises a first bump suppression structure 401 and a second bump suppression structure 402 located at the same bottom electrode 42 and/or the same top electrode 41; the first protrusion inhibiting structure 401 and the second protrusion inhibiting structure 402 are respectively positioned at two side edges of the same bottom electrode 42 and/or the same top electrode 41 which are not adjacent; the first bump restraint structure 401 and the second bump restraint structure 402 are aligned along the second direction y.
Wherein the substrate 10 includes, but is not limited to, monocrystalline silicon, polycrystalline silicon, sapphire, silicon carbide, and homogeneous or heterogeneous material substrates thereof.
The bragg reflector grating 20 comprises alternately arranged low acoustic impedance layers and high acoustic impedance layers, for example the bragg reflector grating 20 of fig. 1 comprises, from bottom to top, a high acoustic impedance layer 23, a second low acoustic impedance layer 22, a high acoustic impedance layer 23, and a first low acoustic impedance layer 21, wherein the first low acoustic impedance layer 21 is in contact with the bottom electrode 42, and the piezoelectric layer 30. The first low acoustic impedance layer 21 and the second low acoustic impedance layer 22 include, but are not limited to, materials having low acoustic impedance such as silicon dioxide, polydimethylsiloxane (PDMS), and the like, and the material of the first low acoustic impedance layer 21 may be the same as or different from the second low acoustic impedance layer 22. The high acoustic impedance layer 23 includes, but is not limited to, a dielectric or metallic material of high acoustic impedance such as metallic tungsten, metallic molybdenum, metallic chromium, hafnium disulfide, and the like.
The piezoelectric layer 30 includes, but is not limited to, a film layer of lithium niobate, lithium carbonate, etc., and in an alternative embodiment, the piezoelectric layer 30 includes Y-cut lithium niobate of-30 ° to 0 °, wherein the Y-cut angle includes-30 ° and 0 °, and the thickness shearing mode with a larger electromechanical coupling coefficient can be excited by using the specific cut lithium niobate film layer, which is favorable for preparing an ultra-high frequency, high coupling bulk acoustic wave resonator, and is expected to be used in a high frequency broadband band of 5G/6G.
Bottom electrode 42 includes, but is not limited to, metallic aluminum, aluminum cylinder alloys, silicon aluminum alloys, and the like, and preferably has an acoustic impedance similar to that of the low acoustic impedance material. The top electrode 41 includes, but is not limited to, a common metal such as molybdenum, aluminum, copper, or other conductive material.
The first protrusion inhibiting structure 401 and the second protrusion inhibiting structure 402 may comprise the same material as the bottom electrode 42 and/or the top electrode 41, or may comprise different materials, which is not limited in this embodiment of the present invention. It should be noted that, in the drawings, the cross-sectional structures of the first bump suppressing structure 401 and the second bump suppressing structure 402 along the section A-A ' are illustrated as rectangular structures, but in other alternative embodiments, the cross-sectional structures of the first bump suppressing structure 401 and the second bump suppressing structure 402 along the section A-A ' may also be triangular, trapezoidal, semicircular, or other structures, or may be irregular structures, and the cross-sectional structures of the first bump suppressing structure 401 and the second bump suppressing structure 402 along the section A-A ' may be the same or different.
Specifically, fig. 3 is a schematic frequency response diagram of a bulk acoustic wave resonator with a notch suppression structure provided in an embodiment of the present invention, where fig. 3 (a) is a schematic frequency response diagram of a bulk acoustic wave resonator with a notch suppression structure, and fig. 3 (b) is a schematic frequency response diagram of a bulk acoustic wave resonator without a notch suppression structure, referring to fig. 1 and fig. 3, a first notch suppression structure 501 and a second notch suppression structure 502 are disposed adjacent to each other along a direction (a first direction x) intersecting with a signal vibration direction in the bulk acoustic wave resonator, and both the first protrusion suppression structure 401 and the second protrusion suppression structure 402 extend along a direction (a second direction y) parallel to the signal vibration direction in the bulk acoustic wave resonator, so that stray modes outside a main mode of the resonator can be effectively blocked, a resonance signal interfering with the main mode of the bulk acoustic wave resonator can be avoided, and a resonance signal of the main mode of the bulk acoustic wave resonator can be avoided from being rapidly dissipated, which is beneficial to improving a quality factor of the bulk acoustic wave resonator; at the same time, the signal propagation of the resonance signal in the bulk acoustic wave resonator is not affected.
Referring to fig. 1 and 2, a first bump suppressing structure 401 and a second bump suppressing structure 402 are disposed at edges of a bottom electrode 42 and/or a top electrode 41 arranged along a direction (second direction y) parallel to a signal vibration direction in a bulk acoustic wave resonator, and by using propagation speeds of a resonance signal in the first bump suppressing structure 401 and the second bump suppressing structure 402 different from those in a bump-free structure, a resonance signal outside a main mode of the bulk acoustic wave resonator can be reflected, and a resonance signal outside the main mode of the bulk acoustic wave resonator can be blocked, so that the resonance signal affecting the main mode of the bulk acoustic wave resonator is avoided, and particularly, a resonance signal propagating and/or vibrating along the second direction y can be blocked, so that a lateral spurious mode is effectively suppressed.
Fig. 4 is a schematic structural diagram of a process for manufacturing a bulk acoustic wave resonator according to an embodiment of the present invention, and referring to fig. 4, a method for manufacturing a bulk acoustic wave resonator may be: (1) Providing a piezoelectric insulating (Piezoelectric-On-Insulator, POI) wafer 90, the POI wafer 90 comprising a piezoelectric insulating substrate 91, an insulating layer 92 and a piezoelectric layer 30; (2) Depositing a conductive layer on the upper surface of the piezoelectric layer 30, patterning to form a bottom electrode 42; (3) Depositing a first low acoustic impedance layer 21 on the upper surface and planarizing the surface by chemical mechanical Polishing (CHEMICAL MECHANICAL Polishing, CMP) or the like; (4) Alternately depositing high and low acoustic impedance layers (23 and 22) to produce a Bragg reflection grating 20; (5) The top surface of the Bragg reflection grating 20 is combined with the substrate 10 by using a wafer bonding technology or a conductive adhesive and other modes; (6) Flipping and removing the piezoelectric insulating substrate 91 and insulating layer 92 of the original POI wafer 90; (7) Etching the piezoelectric layer to form a lower electrode lead-out hole 44, and etching a first groove suppression structure 501 and a second groove suppression structure 502; (8) A conductive layer is formed on the surface of the piezoelectric layer, patterned to form a top electrode 41 and an electrical port, and an electrode lead-out hole 44 is filled to electrically connect the bottom electrode 42 with the electrical port. Wherein the bottom electrode 42 may be embedded in the bottom of the first low acoustic impedance layer 21, the first low acoustic impedance layer 21 may insulate the bottom electrode 42 from the high acoustic impedance layer 23 to attenuate electromagnetic crosstalk generated by the bottom electrode 42 through the substrate 10. The first bump suppressing structure 401 and the second bump suppressing structure 402 may be deposited on the upper surface of the top electrode 41 after the top electrode 41 and the electrical port are prepared, or may be integrally formed with the top electrode 41, which is not limited by the implementation of the present invention.
In an alternative embodiment, the bottom electrode 42 is made of a light conductive material having an acoustic impedance similar to that of the first low acoustic impedance layer 21, and at this time, the frequency of the bulk acoustic wave resonator is affected by the sum of the thicknesses of the bottom electrode 42 and the first low acoustic impedance layer 21, so that the sum of the thicknesses of the bottom electrode 42 and the first low acoustic impedance layer 21 can be ensured to meet the accuracy requirement during the preparation, and the thickness accuracy of the two is not required separately. Therefore, the influence of the thickness of the electrode on the resonance frequency and the thickness precision requirement of the bulk acoustic wave resonator can be reduced, the process difficulty is reduced, and the process stability is improved.
In yet another alternative embodiment, referring to fig. 1 and 2, the thickness of the same bottom electrode 42 and/or the same top electrode 41 where the first bump-inhibiting structure 401 and the second bump-inhibiting structure 402 are located is D1, the thickness of the first bump-inhibiting structure is D01, and the thickness of the second bump-inhibiting structure is D02; wherein 0.8 x D1.ltoreq.D01.ltoreq.1.2 x D1, and/or 0.8 x D1.ltoreq.D02.ltoreq.1.2 x D1. On the one hand, D01 is more than or equal to 0.8D1 and/or D02 is more than or equal to 0.8D1, so that transverse stray modes can be effectively restrained, and the thicknesses of the first protrusion restraining structure 401 and the second protrusion restraining structure 402 are prevented from being too thin to effectively restrain the transverse stray modes; on the other hand, D01 is less than or equal to 1.2 and/or D02 is less than or equal to 1.2 and D1, so that the process difficulty can be reduced, and the mechanical quality factor can be improved.
In yet another alternative embodiment, fig. 5 is a schematic structural diagram of a further bulk acoustic wave resonator provided by the embodiment of the present invention, where fig. 5 (a) is a schematic structural diagram of a top view of the further bulk acoustic wave resonator provided by the embodiment of the present invention, and fig. 5 (B) is a schematic structural diagram of a cross section along B-B' in fig. 5 (a) provided by the embodiment of the present invention, and referring to fig. 5, a maximum width of the same bottom electrode 42 and/or the same top electrode 41 in the second direction y where the first bump suppression structure 401 and the second bump suppression structure 402 are located is W1, a maximum width of the first bump suppression structure 401 in the second direction y is W01, and a maximum width of the second bump suppression structure 402 in the second direction y is W02; wherein, 0< W01 is less than or equal to 0.1 and/or 0< W02 is less than or equal to 0.1 and is equal to 1.
In this way, the ratio of the first bump suppressing structure 401 to the second bump suppressing structure 402 in the same bottom electrode 42 and/or the same top electrode 41 is prevented from being excessively large, so that the areas where the first bump suppressing structure 401 and the second bump suppressing structure 402 are disposed and the areas where the first bump suppressing structure 401 and the second bump suppressing structure 402 are not disposed form different resonance signals, which affects the resonance signals in the bulk acoustic wave resonator.
In a further alternative embodiment, the first bump-inhibiting structure and/or the second bump-inhibiting structure gradually decrease in width in the second direction from being closer to the same bottom electrode and/or the same top electrode being located to being farther from the same bottom electrode and/or the same top electrode being located.
By way of example, with continued reference to fig. 5, the cross-sectional structures of the first bump-suppressing structure 401 and the second bump-suppressing structure 402 along the section A-A 'may be triangular structures as shown, and in other alternative embodiments, the cross-sectional structures of the first bump-suppressing structure 401 and the second bump-suppressing structure 402 along the section A-A' may also be isosceles trapezoids, right-angled trapezoids, semi-circular structures with narrow lower widths and upper widths, so that the concentrated stress at the corners where the first bump-suppressing structure 401 and the second bump-suppressing structure 402 are connected to the same bottom electrode 42 and/or the same top electrode 41 may be reduced, and the process stability may be improved.
According to the bulk acoustic wave resonator provided by the embodiment of the invention, the stray mode can be effectively restrained and the quality factor can be improved by arranging the first groove restraining structure and the second groove restraining structure and the first bulge restraining structure and the second bulge restraining structure which are positioned on the same bottom electrode and/or the same top electrode, so that the bulk acoustic wave resonator with few stray modes, high resonant frequency and large power capacity can be realized, and the bulk acoustic wave resonator has higher performance, so that the requirements of current N79, wiFi 6E and other frequency bands and future 6G frequency bands can be met.
Alternatively, with continued reference to fig. 2 and 4, the bragg reflector grating 20 includes a first low acoustic impedance layer 21 in contact with the bottom electrode 42 and the piezoelectric layer 30; the bragg reflection grating 20 further includes a second low acoustic impedance layer 22 and a high acoustic impedance layer 23 which are alternately disposed on a side of the first low acoustic impedance layer 21 near the substrate 10; the bottom of the first groove suppressing structure 501 and the bottom of the second groove suppressing structure 502 each expose the high acoustic impedance layer 23 in contact with the first low acoustic impedance layer 21.
Illustratively, the bottom of the first groove suppression structure 501 and the bottom of the second groove suppression structure 502 are flush with the top end of the high acoustic impedance layer 23 furthest from the substrate 10. On the one hand, the first low acoustic impedance layer 21 below the first groove suppression structure 501 and the second groove suppression structure 502 is hollowed out, so that the resonance signals of the stray modes can be prevented from interfering with the resonance signals of the bulk acoustic wave resonator through the first low acoustic impedance layer 21; on the other hand, the whole Bragg reflection grating 20 does not need to be hollowed out, which is beneficial to reducing the process difficulty.
Optionally, fig. 6 is a schematic structural diagram of a further bulk acoustic wave resonator according to an embodiment of the present invention, where fig. 6 (a) is a schematic structural diagram of a top view of the further bulk acoustic wave resonator according to an embodiment of the present invention, and fig. 6 (b) is a schematic structural diagram of a cross section along the C-C' section in fig. 6 (a), and referring to fig. 6, both the first groove suppression structure 501 and the second groove suppression structure 502 are filled with a heat conductive material 55 according to an embodiment of the present invention; the acoustic impedance of the thermally conductive material 55 is less than the acoustic impedance of the high acoustic impedance layer 23 in the bragg reflector grating 20, and the thermally conductive material 55 is an insulator. On the one hand, the thermal material 55 has a relatively low acoustic impedance, and may form a reflection with the piezoelectric layer 30, reflecting the resonant signal propagating along the first direction x; on the other hand, the mechanical stability and the heat conduction performance of the bulk acoustic wave resonator can be improved, so that the power capacity of the bulk acoustic wave resonator is improved.
In an alternative embodiment, the acoustic impedance of thermally conductive material 55 is the same as or similar to the acoustic impedance of first low acoustic impedance layer 23.
Alternatively, fig. 7 is a schematic cross-sectional view taken along a section B-B' in fig. 5, and referring to fig. 7, the first bump suppressing structure 401 and the second bump suppressing structure 402 are located on a side of the bottom electrode 42 away from the piezoelectric layer 30; and/or, the first protrusion inhibiting structure 401 and the second protrusion inhibiting structure 402 are both located on a side of the top electrode 41 away from the piezoelectric layer 30; a third bump suppression structure 403 and a fourth bump suppression structure 404 are disposed on a side of at least a portion of the membrane layer in the bragg reflection grating 20 away from the piezoelectric layer 30; the vertical projection of the third bump suppressing structure 403 on the plane of the substrate 10 overlaps with the vertical projection of the first bump suppressing structure 401 on the plane of the substrate 10, and the vertical projection of the fourth bump suppressing structure 404 on the plane of the substrate 10 overlaps with the vertical projection of the second bump suppressing structure 402 on the plane of the substrate 10. In this way, the spurious modes in the bragg reflection grating 20 can be effectively suppressed, and the spurious modes are further reduced, so that signal crosstalk in the bragg reflection grating 20 is weakened, and the bulk acoustic wave resonator has higher performance.
Optionally, fig. 8 is a schematic top view of another bulk acoustic wave resonator according to an embodiment of the present invention, and fig. 9 is a schematic top view of another bulk acoustic wave resonator according to an embodiment of the present invention, and referring to fig. 8 and 9, an extension direction of the first bump suppression structure 401 and an extension direction of the second bump suppression structure 402 both intersect with the second direction y; at least a portion of the extending direction of the first bump-inhibiting structure 401 intersects the first direction x and/or at least a portion of the extending direction of the second bump-inhibiting structure 402 intersects the first direction x.
By setting the extending direction of the first bump suppressing structure 401 and the extending direction of the second bump suppressing structure 402 not to be perpendicular to the second direction y, the active region of the bulk acoustic wave resonator is in a parallelogram shape, so that the acoustic wave propagating along the y direction cannot return along the original path after being reflected by the first bump suppressing structure 401 or the second bump suppressing structure 402, and even if the acoustic wave propagating along the y direction cannot form a standing wave, the effect of further suppressing the spurious mode can be achieved.
It should be noted that, in the drawings, the first protrusion suppressing structure 401 and the second protrusion suppressing structure 402 are only exemplarily shown as parallel or symmetrical linear structures, and in other alternative embodiments, the first protrusion suppressing structure 401 and the second protrusion suppressing structure 402 may also be symmetrical or asymmetrical polygonal structures, wavy structures, or other structures, where the extending direction intersects the second direction y, but at least the extending direction of a part of the area is not perpendicular.
Alternatively, fig. 10 is a schematic structural diagram of a further bulk acoustic wave resonator according to an embodiment of the present invention, where fig. 10 (a) is a schematic structural diagram of a top view of the further bulk acoustic wave resonator according to an embodiment of the present invention, and fig. 10 (b) is a schematic structural diagram of a cross-section along D-D' in fig. 10 (a) according to an embodiment of the present invention, and referring to fig. 10, the first protrusion suppression structure 401 includes a plurality of first sub-protrusion suppression structures 041, and/or the second protrusion suppression structure 402 includes a plurality of second sub-protrusion suppression structures 042.
Specifically, the first protrusion suppression structure 401 and the second protrusion suppression structure 402 include two or more sub-structures (the first sub-protrusion suppression structure 041 and the second sub-protrusion suppression structure 042) arranged along the second direction y, so that the sound velocity can be periodically modulated, the transverse mode of the bulk acoustic wave resonator can be further eliminated, and the performance of the bulk acoustic wave resonator can be improved.
In an alternative embodiment, the number of first sub-protrusion inhibiting structures 041 and the number of second sub-protrusion inhibiting structures 042 located on the same top electrode 41 or the same bottom electrode 42 are the same.
Note that the above is only a preferred embodiment of the present invention and the technical principle applied. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, while the invention has been described in connection with the above embodiments, the invention is not limited to the embodiments, but may be embodied in many other equivalent forms without departing from the spirit or scope of the invention, which is set forth in the following claims.
Claims (10)
1. A bulk acoustic wave resonator, comprising, in order from bottom to top: a substrate, a Bragg reflection gate, a bottom electrode, a piezoelectric layer and a top electrode; the vertical projection of the bottom electrode on the plane of the substrate overlaps with the vertical projection of the top electrode on the plane of the substrate; the resonant signal in the bulk acoustic wave resonator propagates along a vertical direction and vibrates along a second direction, and the second direction is parallel to a plane where the substrate is located;
the bulk acoustic wave resonator further comprises a first groove suppression structure and a second groove suppression structure which are positioned on two opposite sides of the top electrode; the first groove inhibiting structure, the top electrode and the second groove inhibiting structure are sequentially arranged along a first direction, the first direction is also parallel to the plane of the substrate, and the first direction is perpendicular to the second direction; the first groove inhibiting structure and the second groove inhibiting structure both extend along the second direction;
The bulk acoustic wave resonator further comprises a first bump inhibition structure and a second bump inhibition structure which are respectively positioned on the same bottom electrode and/or the same top electrode; the first protrusion inhibiting structure and the second protrusion inhibiting structure are positioned at the edges of the two sides of the bottom electrode and/or the top electrode which are not adjacent to each other; the first bump restraint structure and the second bump restraint structure are aligned along the second direction.
2. The bulk acoustic wave resonator of claim 1, wherein the bragg reflector grating comprises a first low acoustic impedance layer in contact with the bottom electrode and the piezoelectric layer;
the Bragg reflection grating further comprises a second low acoustic impedance layer and a high acoustic impedance layer which are positioned on one side of the first low acoustic impedance layer close to the substrate and are alternately arranged;
the bottom of the first groove suppressing structure and the bottom of the second groove suppressing structure each expose the high acoustic impedance layer in contact with the first low acoustic impedance layer.
3. The bulk acoustic wave resonator according to claim 1, characterized in that both the first and the second recess-suppressing structures are filled with a thermally conductive material; the acoustic impedance of the thermally conductive material is less than the acoustic impedance of the high acoustic impedance layer in the Bragg reflector grating, and the thermally conductive material is an insulator.
4. The bulk acoustic wave resonator according to claim 1, characterized in that the first and second bump inhibiting structures are both located on a side of the bottom electrode remote from the piezoelectric layer; and/or, the first bump inhibition structure and the second bump inhibition structure are both positioned at one side of the top electrode away from the piezoelectric layer;
A third bulge suppression structure and a fourth bulge suppression structure are arranged on one side, away from the piezoelectric layer, of at least part of the film layers in the Bragg reflection grating;
And the vertical projection of the third bulge restraining structure on the plane of the substrate overlaps with the vertical projection of the first bulge restraining structure on the plane of the substrate, and the vertical projection of the fourth bulge restraining structure on the plane of the substrate overlaps with the vertical projection of the second bulge restraining structure on the plane of the substrate.
5. The bulk acoustic wave resonator according to claim 1, characterized in that the extension direction of the first bump suppressing structure and the extension direction of the second bump suppressing structure both intersect the second direction;
At least part of the extending direction of the first protrusion inhibiting structure intersects the first direction, and/or at least part of the extending direction of the second protrusion inhibiting structure intersects the first direction.
6. The bulk acoustic wave resonator of claim 1, wherein the first bump inhibition structure comprises a plurality of first sub-bump inhibition structures and/or the second bump inhibition structure comprises a plurality of second sub-bump inhibition structures.
7. The bulk acoustic wave resonator according to claim 1, characterized in that the thickness of the same bottom electrode and/or the same top electrode where the first and second bump suppression structures are located is D1, the thickness of the first bump suppression structure is D01, and the thickness of the second bump suppression structure is D02;
Wherein 0.8 x D1.ltoreq.D01.ltoreq.1.2 x D1, and/or 0.8 x D1.ltoreq.D02.ltoreq.1.2 x D1.
8. The bulk acoustic wave resonator according to claim 1, characterized in that the maximum width of the same bottom electrode and/or the same top electrode in the second direction, in which a first bump suppression structure and a second bump suppression structure are located, is W1, the maximum width of the first bump suppression structure in the second direction is W01, and the maximum width of the second bump suppression structure in the second direction is W02;
wherein 0 < W01 is less than or equal to 0.1 x W1, and/or 0 < W02 is less than or equal to 0.1 x W1.
9. The bulk acoustic wave resonator according to claim 1, characterized in that the width of the first bump suppressing structure and/or the second bump suppressing structure in the second direction gradually decreases from the same bottom electrode and/or the same top electrode that is located closer to it to the same bottom electrode and/or the same top electrode that is located away from it.
10. The bulk acoustic wave resonator of claim 1, wherein the piezoelectric layer comprises-30 ° to 0 ° Y-cut lithium niobate.
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