CN113794462B - Lamb wave resonator and preparation method thereof - Google Patents
Lamb wave resonator and preparation method thereof Download PDFInfo
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- CN113794462B CN113794462B CN202110894385.0A CN202110894385A CN113794462B CN 113794462 B CN113794462 B CN 113794462B CN 202110894385 A CN202110894385 A CN 202110894385A CN 113794462 B CN113794462 B CN 113794462B
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- 235000019687 Lamb Nutrition 0.000 title claims abstract description 63
- 238000002360 preparation method Methods 0.000 title claims abstract description 19
- 239000000758 substrate Substances 0.000 claims abstract description 95
- 229910052751 metal Inorganic materials 0.000 claims abstract description 85
- 239000002184 metal Substances 0.000 claims abstract description 85
- 238000000034 method Methods 0.000 claims description 58
- 238000000151 deposition Methods 0.000 claims description 51
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims description 36
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 36
- 229910052710 silicon Inorganic materials 0.000 claims description 36
- 239000010703 silicon Substances 0.000 claims description 36
- 239000005360 phosphosilicate glass Substances 0.000 claims description 25
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 claims description 24
- 238000001755 magnetron sputter deposition Methods 0.000 claims description 24
- 238000001020 plasma etching Methods 0.000 claims description 23
- 239000000463 material Substances 0.000 claims description 20
- 239000007853 buffer solution Substances 0.000 claims description 12
- 239000012159 carrier gas Substances 0.000 claims description 12
- 230000008021 deposition Effects 0.000 claims description 12
- 238000001035 drying Methods 0.000 claims description 12
- 229910000040 hydrogen fluoride Inorganic materials 0.000 claims description 12
- 238000002791 soaking Methods 0.000 claims description 12
- JLTRXTDYQLMHGR-UHFFFAOYSA-N trimethylaluminium Chemical compound C[Al](C)C JLTRXTDYQLMHGR-UHFFFAOYSA-N 0.000 claims description 12
- 238000005530 etching Methods 0.000 claims description 11
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 claims description 10
- 229910052721 tungsten Inorganic materials 0.000 claims description 10
- 239000010937 tungsten Substances 0.000 claims description 10
- 229910052782 aluminium Inorganic materials 0.000 claims description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 2
- 230000005540 biological transmission Effects 0.000 abstract description 4
- 230000017525 heat dissipation Effects 0.000 abstract 1
- 230000000052 comparative effect Effects 0.000 description 11
- 230000000694 effects Effects 0.000 description 3
- 239000010409 thin film Substances 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 229910013641 LiNbO 3 Inorganic materials 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 238000003486 chemical etching Methods 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 239000010408 film Substances 0.000 description 1
- 238000009616 inductively coupled plasma Methods 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
- H03H9/205—Constructional features of resonators consisting of piezoelectric or electrostrictive material having multiple resonators
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/02228—Guided bulk acoustic wave devices or Lamb wave devices having interdigital transducers situated in parallel planes on either side of a piezoelectric layer
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/02244—Details of microelectro-mechanical resonators
- H03H9/02393—Post-fabrication trimming of parameters, e.g. resonance frequency, Q factor
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/02244—Details of microelectro-mechanical resonators
- H03H9/02433—Means for compensation or elimination of undesired effects
- H03H9/02448—Means for compensation or elimination of undesired effects of temperature influence
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/01—Manufacture or treatment
- H10N30/08—Shaping or machining of piezoelectric or electrostrictive bodies
- H10N30/081—Shaping or machining of piezoelectric or electrostrictive bodies by coating or depositing using masks, e.g. lift-off
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/01—Manufacture or treatment
- H10N30/08—Shaping or machining of piezoelectric or electrostrictive bodies
- H10N30/082—Shaping or machining of piezoelectric or electrostrictive bodies by etching, e.g. lithography
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/02244—Details of microelectro-mechanical resonators
- H03H2009/02488—Vibration modes
- H03H2009/02496—Horizontal, i.e. parallel to the substrate plane
- H03H2009/02503—Breath-like, e.g. Lam? mode, wine-glass mode
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/02007—Details of bulk acoustic wave devices
- H03H9/02015—Characteristics of piezoelectric layers, e.g. cutting angles
- H03H9/02031—Characteristics of piezoelectric layers, e.g. cutting angles consisting of ceramic
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/02007—Details of bulk acoustic wave devices
- H03H9/02086—Means for compensation or elimination of undesirable effects
- H03H9/02102—Means for compensation or elimination of undesirable effects of temperature influence
Abstract
The invention relates to the technical field of radio frequency filters, in particular to a lamb wave resonator and a preparation method thereof. The lamb wave resonator comprises a substrate from bottom to top, an interdigital bottom electrode, a piezoelectric layer and an interdigital top electrode; a cavity is etched on the substrate; the surface of the piezoelectric layer, which is not covered by the interdigital top electrode, is provided with a reflecting metal layer; the piezoelectric layer has an arcuate edge. In the lamb wave resonator provided by the invention, the reflecting metal layer and the arc-shaped edge of the piezoelectric layer cooperate to effectively limit sound waves in the piezoelectric layer, so that the transmission loss of the sound waves is reduced; in addition, the lamb wave resonator disclosed by the invention has the advantages that the heat dissipation is faster, the temperature of the resonator is reduced, and the power capacity and the quality factor of the resonator are improved.
Description
Technical Field
The invention relates to the technical field of radio frequency filters, in particular to a lamb wave resonator and a preparation method thereof.
Background
Radio frequency filters based on the piezoelectric effect play an important role in the communication field, and are increasingly receiving extensive attention and application. Wherein the thin film bulk acoustic resonator has gradually become an integral part of the rf front-end system due to its excellent performance. The principle of the film bulk acoustic resonator is that electric energy is converted into acoustic energy by utilizing the piezoelectric effect of piezoelectric materials, the acoustic waves are reflected back and forth in the piezoelectric materials to form interference addition, and finally the impedance characteristics of the resonator are changed by the inverse piezoelectric effect. The frequency of the thin film bulk acoustic resonator is determined by the thickness of the piezoelectric material, so that only resonators with the same frequency can be prepared on a single substrate, and the thin film bulk acoustic resonators with multiple frequencies cannot be integrated.
The lamb wave resonator is a novel piezoelectric type radio frequency resonator, the frequency of the lamb wave resonator is determined by the spacing of the interdigital electrodes, and therefore the resonant frequency can be adjusted by adjusting the spacing of the interdigital electrodes, so that the lamb wave resonator is very beneficial to monolithically integrating filters with a plurality of resonant frequencies. However, in order to ensure a high quality factor, the lamb wave resonator needs to be isolated from the substrate by the piezoelectric material, and thus the mechanical stability of the lamb wave resonator is poor. And the heat generated by the resonator cannot be effectively diffused, so that the power capacity of the resonator is limited. With the opening of the 5G era, the frequency band of the radio frequency front end is more complex, and higher requirements are put on the radio frequency front end filter, so that the lamb wave resonator is required to have lower loss and higher quality factor. Therefore, how to improve the quality factor and power capacity of a lamb wave resonator and reduce the acoustic wave transmission loss are key problems facing the lamb wave resonator.
Disclosure of Invention
In view of the foregoing, there is a need to provide a lamb wave resonator and a method for manufacturing the same, which can improve the quality factor and power capacity of the lamb wave resonator and reduce the acoustic wave transmission loss.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
in a first aspect, the present invention provides a lamb wave resonator comprising a bottom-up substrate, an interdigital bottom electrode, a piezoelectric layer, and an interdigital top electrode; a cavity is etched on the substrate; the surface of the piezoelectric layer, which is not covered by the interdigital top electrode, is provided with a reflecting metal layer; the piezoelectric layer has an arcuate edge; the reflective metal layer cooperates with the arcuate edges of the piezoelectric layer to cause total reflection of the acoustic wave at the boundary of air, effectively confining the acoustic wave within the piezoelectric layer.
Further, in the lamb wave resonator described above, the reflective metal layer has an arcuate edge.
Further, in the lamb wave resonator described above, the arcuate edge includes, but is not limited to, an arc and an elliptical arc.
Further, in the lamb wave resonator, the reflective metal layer is made of tungsten. Compared with other metal materials, the acoustic impedance of the metal tungsten is stronger, the acoustic wave can be reflected efficiently, the acoustic wave is prevented from leaking into the substrate, and the acoustic loss is further reduced.
Further, in the lamb wave resonator, the curvature of the arc edge is (0.33-2)/the linear length of the connecting line of the two end points of the arc edge.
Further, in the lamb wave resonator, one or more reflective metal layers are arranged at the arc edge; the arcuate edges of the piezoelectric layer are one or more.
Further, in the lamb wave resonator described above, the bottom and top interdigital electrodes include, but are not limited to Pt, mo, ag, al, au.
Further, in the lamb wave resonator, the piezoelectric layer is piezoelectric ceramic, alN, znO, or LiNbO 3 Is a composite of one or more of the following.
Further, in the lamb wave resonator, the depth of the cavity is 1 μm to 10 μm.
Further, in the lamb wave resonator, the thicknesses of the interdigital top electrode and the interdigital bottom electrode are 50nm to 1000nm.
Further, in the lamb wave resonator, the thickness of the piezoelectric layer is 100nm to 5000nm.
Further, in the lamb wave resonator, the thickness of the reflective metal layer is 10nm to 300nm.
In a second aspect, the present invention provides a method for preparing the lamb wave resonator, which includes the following steps:
step 1: etching a cavity on the surface of the substrate, depositing a sacrificial layer material in the cavity, forming a sacrificial layer, and polishing;
step 2: depositing an interdigital bottom electrode over the sacrificial layer material;
step 3: depositing a piezoelectric layer over the interdigital bottom electrodes;
step 4: preparing an interdigital top electrode above the piezoelectric layer;
step 5: preparing a reflective metal layer on the surface of the piezoelectric layer which is not covered by the top electrode;
step 6: etching an arc edge on the surface of the piezoelectric layer;
step 7: and removing the sacrificial layer.
Further, in the above preparation method of the lamb wave resonator, the preparation method of the cavity includes, but is not limited to, RIE, ICP, or chemical etching.
Further, in the preparation method of the lamb wave resonator, the sacrificial layer material is phosphosilicate glass.
The beneficial effects of the invention are as follows:
in the lamb wave resonator provided by the invention, the reflecting metal layer and the arc-shaped edge of the piezoelectric layer cooperate to effectively limit sound waves in the piezoelectric layer instead of leaking to surrounding substrates, so that the transmission loss of the sound waves is reduced; the piezoelectric layer of the lamb wave resonator is partially etched, so that the temperature of the resonator is reduced, the power capacity and the quality factor of the resonator are improved, and the insertion loss of a device is reduced. Compared with a resonator with a piezoelectric layer with a linear edge, the power capacity and the quality factor of the lamb wave resonator provided by the invention can be increased by more than two times.
Drawings
FIG. 1 is a cross-sectional view of a substrate etched with cavities in example 1;
FIG. 2 is a cross-sectional view of example 1 after the sacrificial layer has been prepared;
FIG. 3 is a cross-sectional view of example 1 after the bottom electrode of the interdigital electrode has been prepared;
FIG. 4 is a cross-sectional view of the piezoelectric layer of example 1;
FIG. 5 is a cross-sectional view of the interdigital top electrode prepared in example 1;
fig. 6 is a top view of the reflective metal layer and the curved edge of the piezoelectric layer prepared in example 1.
In the figure: 101-substrate, 102-cavity, 103-sacrificial layer, 104-interdigital bottom electrode, 105-piezoelectric layer, 106-interdigital top electrode, 107-reflective metal layer, 108-arc edge of piezoelectric layer.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be further clearly and completely described in the following in conjunction with the embodiments of the present invention. It should be noted that the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1
As shown in fig. 1, a lamb wave resonator includes a bottom-up substrate 101, an interdigital bottom electrode 104, a piezoelectric layer 105, and an interdigital top electrode 106; a cavity 102 is etched on the substrate 101; the surface of the piezoelectric layer not covered by the top electrode is provided with a reflective metal layer 107; the piezoelectric layer is etched with an arcuate edge 108.
Wherein the substrate is a silicon substrate, and the depth of the cavity is 4 mu m; the interdigital bottom electrode and the interdigital top electrode are both made of metal Mo, the widths of the interdigital bottom electrode and the interdigital top electrode are both 1000nm, and the thicknesses of the interdigital bottom electrode and the interdigital top electrode are both 400nm; the piezoelectric layer is made of AlN and has a thickness of 1 mu m; the reflective metal layer is made of tungsten and has a thickness of 200nm;
the preparation method of the lamb wave resonator comprises the following steps:
step 1: sequentially soaking and drying a silicon substrate with acetone and hydrofluoric acid buffer solution, and preparing a cavity on the surface of the silicon substrate by using a plasma etching method; depositing phosphosilicate glass in the cavity to form a sacrificial layer 103; the thickness of the phosphosilicate glass is larger than the depth of the cavity, and then the sacrificial layer is polished, and the roughness is smaller than 0.5nm;
step 2: depositing metal Mo above the sacrificial layer by using a magnetron sputtering method, and stripping the metal Mo to form an interdigital bottom electrode;
step 3: depositing a piezoelectric layer AlN above the interdigital bottom electrode by using a radio frequency magnetron sputtering system; deposition parameters are trimethylaluminum flow of 50sccm, NH 3 The flow rate is 3slm, the flow rate of carrier gas Ar is 1slm, the substrate temperature is 950 ℃, and the total pressure of the reaction chamber is 40Torr;
step 4: preparing an interdigital top electrode Mo above the piezoelectric layer AlN by adopting a stripping process;
step 5: preparing a reflective metal layer 107 on the surface of the piezoelectric layer AlN which is not covered by the top electrode by adopting a stripping process;
step 6: and 6 arc edges 108 are etched on the AlN surface of the piezoelectric layer by adopting a plasma etching method, wherein the arc edges are semicircular.
Step 7: and (3) placing the material in gaseous hydrogen fluoride for release, and removing the sacrificial layer.
Example 2
A lamb wave resonator comprises a substrate from bottom to top, an interdigital bottom electrode, a piezoelectric layer and an interdigital top electrode; a cavity is etched on the substrate; the surface of the piezoelectric layer, which is not covered by the top electrode, is provided with a reflecting metal layer; the piezoelectric layer is etched with an arc-shaped edge.
Wherein the substrate is a silicon substrate, and the depth of the cavity is 4 mu m; the interdigital bottom electrode and the interdigital top electrode are both made of metal Mo, the widths of the interdigital bottom electrode and the interdigital top electrode are both 1000nm, and the thicknesses of the interdigital bottom electrode and the interdigital top electrode are both 400nm; the piezoelectric layer is made of AlN and has a thickness of 1 mu m; the reflective metal layer is made of aluminum and has the thickness of 200nm;
the preparation method of the lamb wave resonator in the embodiment comprises the following steps:
step 1: sequentially soaking and drying a silicon substrate with acetone and hydrofluoric acid buffer solution, and preparing a cavity on the surface of the silicon substrate by using a plasma etching method; depositing phosphosilicate glass in the cavity to form a sacrificial layer 103; the thickness of the phosphosilicate glass is larger than the depth of the cavity, and then the sacrificial layer is polished, and the roughness is smaller than 0.5nm;
step 2: depositing metal Mo above the sacrificial layer by using a magnetron sputtering method, and stripping the metal Mo to form an interdigital bottom electrode;
step 3: depositing a piezoelectric layer AlN above the interdigital bottom electrode by using a radio frequency magnetron sputtering system; deposition parameters are trimethylaluminum flow of 50sccm, NH 3 The flow rate is 3slm, the flow rate of carrier gas Ar is 1slm, the substrate temperature is 950 ℃, and the total pressure of the reaction chamber is 40Torr;
step 4: preparing an interdigital top electrode Mo above the piezoelectric layer AlN by adopting a stripping process;
step 5: preparing a reflective metal layer 107 on the surface of the piezoelectric layer AlN which is not covered by the top electrode by adopting a stripping process;
step 6: etching 6 arc edges 108 on the AlN surface of the piezoelectric layer by adopting a plasma etching method, wherein the arc edges are semicircular;
step 7: and (3) placing the material in gaseous hydrogen fluoride for release, and removing the sacrificial layer.
Example 3
A lamb wave resonator comprises a substrate from bottom to top, an interdigital bottom electrode, a piezoelectric layer and an interdigital top electrode; a cavity is etched on the substrate; the surface of the piezoelectric layer, which is not covered by the top electrode, is provided with a reflecting metal layer; the piezoelectric layer is etched with an arc-shaped edge.
Wherein the substrate is a silicon substrate, and the depth of the cavity is 4 mu m; the interdigital bottom electrode and the interdigital top electrode are both made of metal Mo, the thickness is 400nm, and the widths of the interdigital bottom electrode and the interdigital top electrode are both 1000nm; the piezoelectric layer is made of AlN and has a thickness of 1 mu m; the reflective metal layer is made of tungsten and has a thickness of 200nm, and the reflective metal layer is provided with an arc-shaped edge, wherein the curvature of the arc-shaped edge is 0.4/the linear length of the connecting line of two end points of the arc-shaped edge.
The preparation method of the lamb wave resonator in the embodiment comprises the following steps:
step 1: sequentially soaking and drying a silicon substrate with acetone and hydrofluoric acid buffer solution, and preparing a cavity on the surface of the silicon substrate by using a plasma etching method; depositing phosphosilicate glass in the cavity to form a sacrificial layer 103; the thickness of the phosphosilicate glass is larger than the depth of the cavity, and then the sacrificial layer is polished, and the roughness is smaller than 0.5nm;
step 2: depositing metal Mo above the sacrificial layer by using a magnetron sputtering method, and stripping the metal Mo to form an interdigital bottom electrode;
step 3: depositing a piezoelectric layer AlN above the interdigital bottom electrode by using a radio frequency magnetron sputtering system; deposition parameters are trimethylaluminum flow of 50sccm, NH 3 The flow rate is 3slm, the flow rate of carrier gas Ar is 1slm, the substrate temperature is 950 ℃, and the total pressure of the reaction chamber is 40Torr;
step 4: preparing an interdigital top electrode Mo above the piezoelectric layer AlN by adopting a stripping process;
step 5: preparing a reflective metal layer 107 on the surface of the piezoelectric layer AlN which is not covered by the top electrode by adopting a stripping process;
step 6: etching 6 arc edges 108 on the AlN surface of the piezoelectric layer by adopting a plasma etching method, wherein the arc edges are semicircular;
step 7: and (3) placing the material in gaseous hydrogen fluoride for release, and removing the sacrificial layer.
Example 4
A lamb wave resonator comprises a substrate from bottom to top, an interdigital bottom electrode, a piezoelectric layer and an interdigital top electrode; a cavity is etched on the substrate; the surface of the piezoelectric layer, which is not covered by the top electrode, is provided with a reflecting metal layer; the piezoelectric layer is etched with an arc-shaped edge.
Wherein the substrate is a silicon substrate, and the depth of the cavity is 4 mu m; the interdigital bottom electrode and the interdigital top electrode are both made of metal Mo, the thickness is 400nm, and the widths of the interdigital bottom electrode and the interdigital top electrode are both 1000nm; the piezoelectric layer is made of AlN and has a thickness of 1 mu m; the reflective metal layer is made of tungsten and has a thickness of 200nm, and the reflective metal layer is provided with an arc-shaped edge, wherein the curvature of the arc-shaped edge is 1.5/the linear length of the connecting line of two end points of the arc-shaped edge.
The preparation method of the lamb wave resonator in the embodiment comprises the following steps:
step 1: sequentially soaking and drying a silicon substrate with acetone and hydrofluoric acid buffer solution, and preparing a cavity on the surface of the silicon substrate by using a plasma etching method; depositing phosphosilicate glass in the cavity to form a sacrificial layer 103; the thickness of the phosphosilicate glass is larger than the depth of the cavity, and then the sacrificial layer is polished, and the roughness is smaller than 0.5nm;
step 2: depositing metal Mo above the sacrificial layer by using a magnetron sputtering method, and stripping the metal Mo to form an interdigital bottom electrode;
step 3: depositing a piezoelectric layer AlN above the interdigital bottom electrode by using a radio frequency magnetron sputtering system; deposition parameters are trimethylaluminum flow of 50sccm, NH 3 The flow rate is 3slm, the flow rate of carrier gas Ar is 1slm, the substrate temperature is 950 ℃, and the total pressure of the reaction chamber is 40Torr;
step 4: preparing an interdigital top electrode Mo above the piezoelectric layer AlN by adopting a stripping process;
step 5: preparing a reflective metal layer 107 on the surface of the piezoelectric layer AlN which is not covered by the top electrode by adopting a stripping process;
step 6: etching 6 arc edges 108 on the AlN surface of the piezoelectric layer by adopting a plasma etching method, wherein the arc edges are semicircular;
step 7: and (3) placing the material in gaseous hydrogen fluoride for release, and removing the sacrificial layer.
Comparative example 1
A lamb wave resonator comprises a substrate from bottom to top, an interdigital bottom electrode, a piezoelectric layer and an interdigital top electrode; the substrate is etched with a cavity.
Wherein the substrate is a silicon substrate, and the depth of the cavity is 4 mu m; the interdigital bottom electrode and the interdigital top electrode are both made of metal Mo, the thickness is 400nm, and the widths of the interdigital bottom electrode and the interdigital top electrode are both 1000nm; the piezoelectric layer is made of AlN and has a thickness of 1 mu m;
the preparation method of the lamb wave resonator in the comparative example comprises the following steps:
step 1: sequentially soaking and drying a silicon substrate with acetone and hydrofluoric acid buffer solution, and preparing a cavity on the surface of the silicon substrate by using a plasma etching method; depositing phosphosilicate glass in the cavity to form a sacrificial layer; the thickness of the phosphosilicate glass is larger than the depth of the cavity, and then the sacrificial layer is polished, and the roughness is smaller than 0.5nm;
step 2: depositing metal Mo above the sacrificial layer by using a magnetron sputtering method, and stripping the metal Mo to form an interdigital bottom electrode;
step 3: depositing a piezoelectric layer AlN above the interdigital bottom electrode by using a radio frequency magnetron sputtering system; deposition parameters are trimethylaluminum flow of 50sccm, NH 3 The flow rate is 3slm, the flow rate of carrier gas Ar is 1slm, the substrate temperature is 950 ℃, and the total pressure of the reaction chamber is 40Torr;
step 4: preparing an interdigital top electrode Mo above the piezoelectric layer AlN by adopting a stripping process;
step 5: and (3) placing the material in gaseous hydrogen fluoride for release, and removing the sacrificial layer.
Comparative example 2
A lamb wave resonator comprises a substrate from bottom to top, an interdigital bottom electrode, a piezoelectric layer and an interdigital top electrode; a cavity is etched on the substrate; the surface of the piezoelectric layer not covered by the top electrode is provided with a reflective metal layer.
Wherein the substrate is a silicon substrate, and the depth of the cavity is 4 mu m; the interdigital bottom electrode and the interdigital top electrode are both made of metal Mo, the thickness is 400nm, and the widths of the interdigital bottom electrode and the interdigital top electrode are both 1000nm; the piezoelectric layer is made of AlN and has a thickness of 1 mu m; the reflective metal layer is made of tungsten and has a thickness of 200nm;
the preparation method of the lamb wave resonator in the comparative example comprises the following steps:
step 1: sequentially soaking and drying a silicon substrate with acetone and hydrofluoric acid buffer solution, and preparing a cavity on the surface of the silicon substrate by using a plasma etching method; depositing phosphosilicate glass in the cavity to form a sacrificial layer; the thickness of the phosphosilicate glass is larger than the depth of the cavity, and then the sacrificial layer is polished, and the roughness is smaller than 0.5nm;
step 2: depositing metal Mo above the sacrificial layer by using a magnetron sputtering method, and stripping the metal Mo to form an interdigital bottom electrode;
step 3: depositing a piezoelectric layer AlN above the interdigital bottom electrode by using a radio frequency magnetron sputtering system; deposition parameters are trimethylaluminum flow of 50sccm, NH 3 The flow rate is 3slm, the flow rate of carrier gas Ar is 1slm, the substrate temperature is 950 ℃, and the total pressure of the reaction chamber is 40Torr;
step 4: preparing an interdigital top electrode Mo above the piezoelectric layer AlN by adopting a stripping process;
step 5: preparing a reflective metal layer 107 on the surface of the piezoelectric layer AlN which is not covered by the top electrode by adopting a stripping process;
step 6: and (3) placing the material in gaseous hydrogen fluoride for release, and removing the sacrificial layer.
Comparative example 3
A lamb wave resonator comprises a substrate from bottom to top, an interdigital bottom electrode, a piezoelectric layer and an interdigital top electrode; a cavity is etched on the substrate; the piezoelectric layer is etched with an arc-shaped edge.
Wherein the substrate is a silicon substrate, and the depth of the cavity is 4 mu m; the interdigital bottom electrode and the interdigital top electrode are both made of metal Mo, the thickness is 400nm, and the widths of the interdigital bottom electrode and the interdigital top electrode are both 1000nm; the piezoelectric layer material was AlN, and the thickness was 1. Mu.m.
The preparation method of the lamb wave resonator in the embodiment comprises the following steps:
step 1: sequentially soaking and drying a silicon substrate with acetone and hydrofluoric acid buffer solution, and preparing a cavity on the surface of the silicon substrate by using a plasma etching method; depositing phosphosilicate glass in the cavity to form a sacrificial layer; the thickness of the phosphosilicate glass is larger than the depth of the cavity, and then the sacrificial layer is polished, and the roughness is smaller than 0.5nm;
step 2: depositing metal Mo above the sacrificial layer by using a magnetron sputtering method, and stripping the metal Mo to form an interdigital bottom electrode;
step 3: depositing a piezoelectric layer AlN above the interdigital bottom electrode by using a radio frequency magnetron sputtering system; deposition parameters are trimethylaluminum flow of 50sccm, NH 3 The flow rate is 3slm, the flow rate of carrier gas Ar is 1slm, the substrate temperature is 950 ℃, and the total pressure of the reaction chamber is 40Torr;
step 4: preparing an interdigital top electrode Mo above the piezoelectric layer AlN by adopting a stripping process;
step 5: etching 6 arc edges 108 on the AlN surface of the piezoelectric layer by adopting a plasma etching method, wherein the arc edges are semicircular;
step 6: and (3) placing the material in gaseous hydrogen fluoride for release, and removing the sacrificial layer.
Comparative example 4
A lamb wave resonator comprises a substrate from bottom to top, an interdigital bottom electrode, a piezoelectric layer and an interdigital top electrode; a cavity is etched on the substrate; the surface of the piezoelectric layer, which is not covered by the top electrode, is provided with a reflecting metal layer; the piezoelectric layer is etched with an arc-shaped edge.
Wherein the substrate is a silicon substrate, and the depth of the cavity is 4 mu m; the interdigital bottom electrode and the interdigital top electrode are both made of metal Mo, the thickness is 400nm, and the widths and the thicknesses of the interdigital bottom electrode and the interdigital top electrode are both 1000nm; the piezoelectric layer is made of AlN and has a thickness of 1 mu m; the reflective metal layer is made of tungsten and has a thickness of 200nm, and the reflective metal layer is provided with an arc-shaped edge, wherein the curvature of the arc-shaped edge is 0.1/the linear length of the connecting line of two end points of the arc-shaped edge.
The preparation method of the lamb wave resonator in the embodiment comprises the following steps:
step 1: sequentially soaking and drying a silicon substrate with acetone and hydrofluoric acid buffer solution, and preparing a cavity on the surface of the silicon substrate by using a plasma etching method; depositing phosphosilicate glass in the cavity to form a sacrificial layer; the thickness of the phosphosilicate glass is larger than the depth of the cavity, and then the sacrificial layer is polished, and the roughness is smaller than 0.5nm;
step 2: depositing metal Mo above the sacrificial layer by using a magnetron sputtering method, and stripping the metal Mo to form an interdigital bottom electrode;
step 3: depositing a piezoelectric layer AlN above the interdigital bottom electrode by using a radio frequency magnetron sputtering system; deposition parameters are trimethylaluminum flow of 50sccm, NH 3 The flow rate is 3slm, the flow rate of carrier gas Ar is 1slm, the substrate temperature is 950 ℃, and the total pressure of the reaction chamber is 40Torr;
step 4: preparing an interdigital top electrode Mo above the piezoelectric layer AlN by adopting a stripping process;
step 5: preparing a reflective metal layer 107 on the surface of the piezoelectric layer AlN which is not covered by the top electrode by adopting a stripping process;
step 6: etching 6 arc edges 108 on the AlN surface of the piezoelectric layer by adopting a plasma etching method, wherein the arc edges are semicircular;
step 7: and (3) placing the material in gaseous hydrogen fluoride for release, and removing the sacrificial layer.
Data comparison
The quality factor of the resonator prepared in example 1 was examined to be about 2500; the figure of merit for example 2 is about 2200; the figure of merit for example 3 was 2000; the figure of merit for example 4 is about 2350; the figure of merit for comparative example 1 is about 1500; the figure of merit for comparative example 2 was about 1760; the figure of merit for comparative example 3 is about 2000; the quality factor of comparative example 4 was about 1830. It can be seen that the resonator quality factor of the present invention is improved by about 1000 as compared with comparative example 1 (resonator without introducing the arc edge and the metal reflective layer).
The foregoing examples illustrate only a few embodiments of the invention and are described in detail herein without thereby limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.
Claims (4)
1. A lamb wave resonator, characterized in that the lamb wave resonator comprises a bottom-up substrate, an interdigital bottom electrode, a piezoelectric layer and an interdigital top electrode; a cavity is etched on the substrate; the surface of the piezoelectric layer, which is not covered by the top electrode, is provided with a reflecting metal layer; the piezoelectric layer is etched with an arc edge; wherein the substrate is a silicon substrate, and the depth of the cavity is 4 mu m; the interdigital bottom electrode and the interdigital top electrode are both made of metal Mo, the widths of the interdigital bottom electrode and the interdigital top electrode are 1000nm, and the thicknesses of the interdigital bottom electrode and the interdigital top electrode are 400nm; the piezoelectric layer is made of AlN and has a thickness of 1 mu m; the reflective metal layer is made of tungsten and has a thickness of 200nm;
the preparation method of the lamb wave resonator comprises the following steps:
step 1: sequentially soaking and drying a silicon substrate with acetone and hydrofluoric acid buffer solution, and preparing a cavity on the surface of the silicon substrate by using a plasma etching method; depositing phosphosilicate glass in the cavity to form a sacrificial layer; the thickness of the phosphosilicate glass is larger than the depth of the cavity, and then the sacrificial layer is polished, and the roughness is smaller than 0.5nm;
step 2: depositing metal Mo above the sacrificial layer by using a magnetron sputtering method, and stripping the metal Mo to form an interdigital bottom electrode;
step 3: depositing a piezoelectric layer AlN above the interdigital bottom electrode by using a radio frequency magnetron sputtering system; the deposition parameters are that the flow rate of trimethylaluminum is 50sccm, the flow rate of NH3 is 3slm, the flow rate of carrier gas Ar is 1slm, the temperature of the substrate is 950 ℃, and the total pressure of the reaction chamber is 40Torr;
step 4: preparing an interdigital top electrode Mo above the piezoelectric layer AlN by adopting a stripping process;
step 5: preparing a reflective metal layer on the surface of the piezoelectric layer AlN which is not covered by the top electrode by adopting a stripping process;
step 6: etching 6 arc edges on the AlN surface of the piezoelectric layer by adopting a plasma etching method, wherein the arc edges are semicircular;
step 7: and (3) placing the material in gaseous hydrogen fluoride for release, and removing the sacrificial layer.
2. A lamb wave resonator, characterized in that the lamb wave resonator comprises a bottom-up substrate, an interdigital bottom electrode, a piezoelectric layer and an interdigital top electrode; a cavity is etched on the substrate; the surface of the piezoelectric layer, which is not covered by the top electrode, is provided with a reflecting metal layer; the piezoelectric layer is etched with an arc edge; wherein the substrate is a silicon substrate, and the depth of the cavity is 4 mu m; the interdigital bottom electrode and the interdigital top electrode are both made of metal Mo, the widths of the interdigital bottom electrode and the interdigital top electrode are both 1000nm, and the thicknesses of the interdigital bottom electrode and the interdigital top electrode are both 400nm; the piezoelectric layer is made of AlN and has a thickness of 1 mu m; the reflective metal layer is made of aluminum and has the thickness of 200nm;
the preparation method of the lamb wave resonator comprises the following steps:
step 1: sequentially soaking and drying a silicon substrate with acetone and hydrofluoric acid buffer solution, and preparing a cavity on the surface of the silicon substrate by using a plasma etching method; depositing phosphosilicate glass in the cavity to form a sacrificial layer; the thickness of the phosphosilicate glass is larger than the depth of the cavity, and then the sacrificial layer is polished, and the roughness is smaller than 0.5nm;
step 2: depositing metal Mo above the sacrificial layer by using a magnetron sputtering method, and stripping the metal Mo to form an interdigital bottom electrode;
step 3: depositing a piezoelectric layer AlN above the interdigital bottom electrode by using a radio frequency magnetron sputtering system; the deposition parameters are that the flow rate of trimethylaluminum is 50sccm, the flow rate of NH3 is 3slm, the flow rate of carrier gas Ar is 1slm, the temperature of the substrate is 950 ℃, and the total pressure of the reaction chamber is 40Torr;
step 4: preparing an interdigital top electrode Mo above the piezoelectric layer AlN by adopting a stripping process;
step 5: preparing a reflective metal layer on the surface of the piezoelectric layer AlN which is not covered by the top electrode by adopting a stripping process;
step 6: etching 6 arc edges on the AlN surface of the piezoelectric layer by adopting a plasma etching method, wherein the arc edges are semicircular;
step 7: and (3) placing the material in gaseous hydrogen fluoride for release, and removing the sacrificial layer.
3. A lamb wave resonator, characterized in that the lamb wave resonator comprises a bottom-up substrate, an interdigital bottom electrode, a piezoelectric layer and an interdigital top electrode; a cavity is etched on the substrate; the surface of the piezoelectric layer, which is not covered by the top electrode, is provided with a reflecting metal layer; the piezoelectric layer is etched with an arc edge; wherein the substrate is a silicon substrate, and the depth of the cavity is 4 mu m; the interdigital bottom electrode and the interdigital top electrode are both made of metal Mo, the thickness is 400nm, and the widths of the interdigital bottom electrode and the interdigital top electrode are both 1000nm; the piezoelectric layer is made of AlN and has a thickness of 1 mu m; the reflective metal layer is made of tungsten and has a thickness of 200nm, and the reflective metal layer is provided with an arc edge, wherein the curvature of the arc edge is 0.4/the linear length of the connecting line of two end points of the arc edge;
the preparation method of the lamb wave resonator comprises the following steps:
step 1: sequentially soaking and drying a silicon substrate with acetone and hydrofluoric acid buffer solution, and preparing a cavity on the surface of the silicon substrate by using a plasma etching method; depositing phosphosilicate glass in the cavity to form a sacrificial layer; the thickness of the phosphosilicate glass is larger than the depth of the cavity, and then the sacrificial layer is polished, and the roughness is smaller than 0.5nm;
step 2: depositing metal Mo above the sacrificial layer by using a magnetron sputtering method, and stripping the metal Mo to form an interdigital bottom electrode;
step 3: depositing a piezoelectric layer AlN above the interdigital bottom electrode by using a radio frequency magnetron sputtering system; the deposition parameters are that the flow rate of trimethylaluminum is 50sccm, the flow rate of NH3 is 3slm, the flow rate of carrier gas Ar is 1slm, the temperature of the substrate is 950 ℃, and the total pressure of the reaction chamber is 40Torr;
step 4: preparing an interdigital top electrode Mo above the piezoelectric layer AlN by adopting a stripping process;
step 5: preparing a reflective metal layer on the surface of the piezoelectric layer AlN which is not covered by the top electrode by adopting a stripping process;
step 6: etching 6 arc edges on the AlN surface of the piezoelectric layer by adopting a plasma etching method, wherein the arc edges are semicircular;
step 7: and (3) placing the material in gaseous hydrogen fluoride for release, and removing the sacrificial layer.
4. A lamb wave resonator, characterized in that the lamb wave resonator comprises a bottom-up substrate, an interdigital bottom electrode, a piezoelectric layer and an interdigital top electrode; a cavity is etched on the substrate; the surface of the piezoelectric layer, which is not covered by the top electrode, is provided with a reflecting metal layer; the piezoelectric layer is etched with an arc edge; wherein the substrate is a silicon substrate, and the depth of the cavity is 4 mu m; the interdigital bottom electrode and the interdigital top electrode are both made of metal Mo, the thickness is 400nm, and the widths of the interdigital bottom electrode and the interdigital top electrode are both 1000nm; the piezoelectric layer is made of AlN and has a thickness of 1 mu m; the reflective metal layer is made of tungsten and has a thickness of 200nm, and the reflective metal layer is provided with an arc edge, wherein the curvature of the arc edge is 1.5/the linear length of the connecting line of two end points of the arc edge;
the preparation method of the lamb wave resonator comprises the following steps:
step 1: sequentially soaking and drying a silicon substrate with acetone and hydrofluoric acid buffer solution, and preparing a cavity on the surface of the silicon substrate by using a plasma etching method; depositing phosphosilicate glass in the cavity to form a sacrificial layer; the thickness of the phosphosilicate glass is larger than the depth of the cavity, and then the sacrificial layer is polished, and the roughness is smaller than 0.5nm;
step 2: depositing metal Mo above the sacrificial layer by using a magnetron sputtering method, and stripping the metal Mo to form an interdigital bottom electrode;
step 3: depositing a piezoelectric layer AlN above the interdigital bottom electrode by using a radio frequency magnetron sputtering system; the deposition parameters are that the flow rate of trimethylaluminum is 50sccm, the flow rate of NH3 is 3slm, the flow rate of carrier gas Ar is 1slm, the temperature of the substrate is 950 ℃, and the total pressure of the reaction chamber is 40Torr;
step 4: preparing an interdigital top electrode Mo above the piezoelectric layer AlN by adopting a stripping process;
step 5: preparing a reflective metal layer on the surface of the piezoelectric layer AlN which is not covered by the top electrode by adopting a stripping process;
step 6: etching 6 arc edges on the AlN surface of the piezoelectric layer by adopting a plasma etching method, wherein the arc edges are semicircular;
step 7: and (3) placing the material in gaseous hydrogen fluoride for release, and removing the sacrificial layer.
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