CN115567029A - Film bulk acoustic resonator with multilayer composite substrate and preparation method thereof - Google Patents
Film bulk acoustic resonator with multilayer composite substrate and preparation method thereof Download PDFInfo
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
- H03H9/17—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator
- H03H9/171—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator implemented with thin-film techniques, i.e. of the film bulk acoustic resonator [FBAR] type
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
- H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
- H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
-
- 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
- H03H9/02047—Treatment of substrates
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
- H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
- H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
- H03H2003/023—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks the resonators or networks being of the membrane type
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- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)
Abstract
The invention provides a film bulk acoustic resonator with a multilayer composite substrate and a preparation method thereof, wherein the film bulk acoustic resonator comprises a first substrate, a second substrate, a third substrate, a bottom electrode, a piezoelectric layer and a top electrode; the third substrate, the second substrate and the first substrate are sequentially stacked to form a composite substrate; the bottom electrode is arranged on the third substrate; the piezoelectric layer is arranged on the bottom electrode, and is connected with the bottom electrode and the third substrate; a cavity structure is formed among the third substrate, the bottom electrode and the piezoelectric layer; the top electrode is arranged on the piezoelectric layer; a release hole opening is provided in the piezoelectric layer, the release hole opening communicating with the cavity. The invention can obtain a cavity with high mechanical stability and almost no residue, can limit the parasitic capacitance by virtue of the arrangement of the composite substrate with gradually increasing resistivity, and has the advantages of simple process and easy implementation.
Description
Technical Field
The invention relates to the technical field of resonators, in particular to a film bulk acoustic resonator with a multilayer composite substrate and a preparation method thereof.
Background
With the rapid development of wireless communication technology, the communication frequency band tends to be higher and denser. The trend of high frequency and density needs to meet the high requirements of high communication frequency, large bandwidth and dense communication frequency division, so that the filter of the radio frequency front end plays a crucial role in the wireless communication system. The filter is formed by connecting a plurality of resonators in series and in parallel, and the cavity is used as a key structure of the bulk acoustic wave resonator, so that acoustic isolation can be effectively formed between the resonator and the cavity to inhibit the energy of the resonator from escaping to the substrate.
The prior art has primarily provided cavities in the substrate, backside notching or replacing the cavities by SMR structures to achieve acoustic isolation. As shown in fig. 15, for the cavity in the substrate, after the sacrificial layer filled in the cavity and the wet chemical completely react, a cavity structure in the schematic diagram is formed, and due to the long-time chemical soaking and stress action of the film layer on the cavity, the defects of tympanic membrane, membrane cracking and even collapse are easily caused during or after the cavity is released, and in addition, no multi-layer composite substrate can cause the problem of electric energy leakage; as shown in fig. 16, the SMR replaces the cavity, the bragg reflector replaces the cavity as the acoustic reflector, the bragg reflector is complicated to manufacture, requires a plurality of times of CMP processes, and has a lower reflection efficiency of the longitudinal wave than the cavity. (ii) a As shown in fig. 17, the back-side trench etching technology is mainly implemented by a wet etching technology, the back-side substrate is too thick in the actual process and can reach more than 100um, especially, the isotropic characteristics of the wet etching technology make the shapes, angles and positions of the trenches uncontrollable, and in addition, the etchant has a risk of corroding the piezoelectric layer, so that it is difficult to implement the function of acoustic isolation between the filter and the substrate.
Patent document CN107809221A discloses a cavity type film bulk acoustic resonator and a preparation method thereof, comprising a supporting substrate, a supporting layer, a film structure layer and a top electrode; a cavity formed by the supporting substrate, the supporting layer and the thin film structure layer is an air cavity, and the supporting substrate is an air cavity bottom; the supporting layer is arranged at the edge of the surface of the supporting substrate to form an air cavity wall; the thin film structure layer is arranged on the supporting substrate to form an air cavity cover; the thin film structure layer is respectively provided with a bottom electrode and a piezoelectric layer from bottom to top, and the top electrode is positioned on the piezoelectric layer. However, the technical solution of the patent document is different from the present application in three points: a. the structure is different, and the cavity of the patent document is enclosed by a supporting layer, a bottom electrode, a piezoelectric layer and a substrate; b. the cavity preparation method differs in that the cavity of this patent document is formed by a bonding technique with two substrates (one of which has been removed by a lift-off technique); c. the substrates are different, the patent document is a two-layer substrate, the application is a three-layer composite substrate, and the resistivity is gradually increased; in addition, in the patent document, au and Sn have extremely high ductility, and Au and Sn are used as supporting layers, and the supporting layers deform or even collapse the cavity when the device works, and the temperature rises to remove the prepared substrate by stripping with an etching solution containing HF.
Disclosure of Invention
In view of the defects in the prior art, the invention aims to provide a film bulk acoustic resonator with a multilayer composite substrate and a preparation method thereof.
The film bulk acoustic resonator with the multilayer composite substrate comprises a first substrate, a second substrate, a third substrate, a bottom electrode, a piezoelectric layer and a top electrode;
the third substrate, the second substrate and the first substrate are sequentially stacked to form a composite substrate;
the bottom electrode is arranged on the third substrate; the piezoelectric layer is arranged on the bottom electrode, and is connected with the bottom electrode and the third substrate;
a cavity structure is formed among the third substrate, the bottom electrode and the piezoelectric layer; the top electrode is disposed on the piezoelectric layer;
a release hole opening is provided in the piezoelectric layer, the release hole opening communicating with the cavity.
Preferably, the resistivity of the first substrate, the second substrate and the third substrate increases step by step.
Preferably, the first substrate is a silicon wafer, the second substrate is a silicon wafer, and the third substrate is SiO 2 Layer or Si 3 N 4 A layer;
the first substrate has a resistivity of 50-1000 Ω -Cm, the second substrate has a resistivity of 2000 Ω -Cm or more, and the third substrate has a resistivity of 10 Ω -Cm 10 Omega, cm above.
The invention also provides a preparation method of the film bulk acoustic resonator with the multilayer composite substrate, which is based on the film bulk acoustic resonator with the multilayer composite substrate and comprises the following steps:
step 1: forming a second substrate on the first substrate, and enabling the first substrate and the second substrate to form a composite base;
and 2, step: forming a third substrate on the second substrate, and enabling the first substrate, the second substrate and the third substrate to form a composite base;
and step 3: forming a sacrificial layer on the third substrate, and patterning the sacrificial layer;
and 4, step 4: forming a bottom electrode on the sacrificial layer, and patterning the bottom electrode;
and 5: forming a piezoelectric layer on the bottom electrode and then forming a top electrode on the piezoelectric layer;
step 6: opening the bottom electrode until the bottom electrode is exposed, and opening the release hole until the sacrificial layer is exposed;
and 7: cavity release is accomplished by etching.
Preferably, in step 1, the first substrate is a silicon wafer, and the second substrate is provided by any one of the following two ways:
the method I comprises the following steps: arranging a silicon wafer on the first substrate, wherein the silicon wafer is bonded with the first substrate through silicon-silicon to form a composite base, and the silicon wafer is used as the second substrate;
the second method comprises the following steps: and growing a single crystal Si thin film on the first substrate by an MOCVD (metal organic chemical vapor deposition) process, an ALD (atomic layer deposition) process or a PECVD (plasma enhanced chemical vapor deposition) process, wherein the grown single crystal Si thin film is used as the second substrate.
Preferably, in the step 2, the third substrate is provided by any one of the following two methods:
the first method is as follows: growing SiO on the second substrate by PECVD process or PVD process 2 Film or Si 3 N 4 Film of said SiO 2 Film or said Si 3 N 4 A film as the third substrate;
the second method comprises the following steps: forming SiO on part of the second substrate by thermal oxidation process 2 Layer of formed SiO 2 The layer serves as the third substrate.
Preferably, in the step 3, the sacrificial layer is grown through an MOCVD process, an ALD process or a PECVD process;
the patterning of the sacrificial layer is completed through the following steps in sequence: gluing, exposing, developing, RIE or IBE, dry degumming and/or wet degumming and Plasma cleaning;
the sacrificial layer adopts Si, and the Plasma cleaning process adopts H 2 And (3) a Plasma treatment process.
Preferably, in the step 4, the bottom electrode has a single-layer structure or a multi-layer structure;
when the bottom electrode is of a single-layer structure, any one of the following materials is selected: mo, ag, au, cu, ti, al, ru and Pt;
when the bottom electrode is of a multilayer structure, at least two materials are selected as follows: mo, ag, au, cu, ti, al, ru and Pt;
the patterning of the bottom electrode is completed through the following steps in sequence: gumming, exposing, developing, RIE or IBE, dry stripping and/or wet stripping.
Preferably, in the step 5, alN is used as the piezoelectric layer, and the piezoelectric layer is grown on the bottom electrode by a metal type or poisoning type Sputter process;
the top electrode is of a single-layer structure or a multi-layer structure;
when the top electrode is of a single-layer structure, any one of the following materials is selected: mo, ag, au, cu, ti, al, ru, pt;
when the top electrode is of a multilayer structure, at least two materials are selected as follows: mo, ag, au, cu, ti, al, ru and Pt;
the patterning of the top electrode is completed sequentially through the following steps: gumming, exposing, developing, RIE or IBE, dry stripping and/or wet stripping.
Preferably, in the step 6, the opening is completed sequentially by: gumming, exposing, developing, RIE or IBE, dry stripping and/or wet stripping;
in the step 7, the cavity release is completed through dry etching, and the etching gas is XeF 2 And the release hole is in contact with the sacrificial layer, and the release hole and the sacrificial layer are chemically reacted and are not in contact with the bottom electrode, the top electrode, the piezoelectric layer and the third substrate.
Compared with the prior art, the invention has the following beneficial effects:
1. the composite substrate has very high resistivity, is increased from bottom to top, effectively inhibits electric energy leakage to improve the Q value of a resonator, inhibits the aggregation of current carriers and forms a potential difference with an electrode so as to inhibit parasitic capacitance to a certain extent;
2. the preparation method can obtain a cavity with high mechanical stability so as to avoid collapse of a device or cracking of a film layer in the working process;
3. the invention can obtain a cavity with almost no residue, thereby ensuring the accuracy of the characteristic frequency of the device and avoiding generating unnecessary transverse mode clutter.
Drawings
Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:
FIG. 1 is a schematic view showing a positional relationship among a boundary of an electrode, a boundary of a cavity, and a release hole;
FIG. 2 isbase:Sub>A cross-sectional view taken along line A-A of FIG. 1;
FIG. 3 is a cross-sectional view taken along line B-B of FIG. 1;
FIGS. 4 to 14 are schematic views of the structure forming process in the case of production by the production method of the present invention;
FIG. 15 is a schematic diagram of a cavity in a substrate according to the prior art;
FIG. 16 is a schematic diagram of a prior art SMR replacement cavity;
fig. 17 is a schematic diagram of a back-side grooved structure in the prior art.
The figures show that:
Bottom electrode opening 110 of piezoelectric layer 105
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. All falling within the scope of the invention.
Example 1:
as shown in fig. 1 to 14, this embodiment provides a film bulk acoustic resonator with a multilayer composite substrate, which includes a first substrate 101, a second substrate 102, a third substrate 103, a bottom electrode 104, a piezoelectric layer 105, and a top electrode 107, where the third substrate 103, the second substrate 102, and the first substrate 101 are sequentially stacked to form a composite substrate, the bottom electrode 104 is disposed on the third substrate 103, the piezoelectric layer 105 is disposed on the bottom electrode 104, the piezoelectric layer 105 is connected to the bottom electrode 104 and the third substrate 103, a cavity 106 structure is formed among the third substrate 103, the bottom electrode 104, and the piezoelectric layer 105, the top electrode 107 is disposed on the piezoelectric layer 105, and the piezoelectric layer 105 is provided with a bottom electrode opening 110 and a release hole opening; the bottom electrode 104 is electrically connected to an external resonator or external circuit through the bottom electrode opening 110; the relief hole opening communicates with the cavity 106. The resistivities of the first substrate 101, the second substrate 102 and the third substrate 103 are gradually increased.
The embodiment also provides a preparation method of the film bulk acoustic resonator with the multilayer composite substrate, based on the film bulk acoustic resonator with the multilayer composite substrate, which includes the following steps:
step 1: forming a second substrate 102 on a first substrate 101, so that the first substrate 101 and the second substrate 102 form a composite base; the first substrate 101 is a silicon wafer, and the second substrate 102 is provided by any one of the following two methods:
the first method is as follows: arranging a silicon wafer on the first substrate 101, wherein the silicon wafer is bonded with the first substrate 101 through silicon-silicon to form a composite base, and the silicon wafer is used as the second substrate 102;
the second method comprises the following steps: a single crystal Si thin film is grown on the first substrate 101 by an MOCVD process, an ALD process, or a PECVD process, and the grown single crystal Si thin film serves as the second substrate 102.
And 2, step: forming a third substrate 103 on the second substrate 102, so that the first substrate 101, the second substrate 102 and the third substrate 103 form a composite base; the third substrate 103 is provided by any one of the following two ways:
the method I comprises the following steps: growing a SiO2 thin film or a Si3N4 thin film on the second substrate 102 by a PECVD process or a PVD process, the SiO2 thin film or the Si3N4 thin film serving as the third substrate 103;
the second method comprises the following steps: forming a SiO2 layer on a portion of the second substrate 102 by a thermal oxidation process, wherein the formed SiO2 layer serves as the third substrate 103.
And 3, step 3: forming a sacrificial layer on the third substrate 103, and patterning the sacrificial layer; growing a sacrificial layer by an MOCVD process, an ALD process or a PECVD process;
the patterning of the sacrificial layer is completed through the following steps in sequence: gumming, exposing, developing, RIE or IBE, dry degumming and/or wet degumming and Plasma cleaning. Namely, the following ways can be adopted: a. gluing → exposure → development → RIE → dry glue removal and Plasma cleaning; b. gluing → exposure → development → RIE → wet glue removal and Plasma cleaning; c. gluing → exposure → development → RIE → dry glue removal + wet glue removal and Plasma cleaning; d. gluing → exposure → development → IBE → dry glue removal and Plasma cleaning; e. gluing → exposure → development → IBE → wet glue removal and Plasma cleaning; f. glue spreading → exposure → development → IBE → dry glue removing + wet glue removing and Plasma cleaning.
The sacrificial layer adopts Si, and the Plasma cleaning process adopts H 2 And (4) a Plasma treatment process.
And 4, step 4: forming a bottom electrode 104 on the sacrificial layer, and patterning the bottom electrode 104; the bottom electrode 104 has a single-layer structure or a multi-layer structure;
when the bottom electrode 104 is a single-layer structure, any one of the following materials is selected: mo, ag, au, cu, ti, al, ru and Pt;
when the bottom electrode 104 has a multilayer structure, at least two materials are selected as follows: mo, ag, au, cu, ti, al, ru, pt;
the patterning of the bottom electrode 104 is completed sequentially by the following steps: gumming, exposing, developing, RIE or IBE, dry stripping and/or wet stripping.
And 5: forming a piezoelectric layer 105 on the bottom electrode 104, and then forming a top electrode 107 on the piezoelectric layer 105; growing the piezoelectric layer 105 on the bottom electrode 104 by using AlN as the piezoelectric layer 105 through a metal type or poisoning type Sputter process;
the top electrode 107 is of a single-layer structure or a multi-layer structure;
when the top electrode 107 is a single-layer structure, any one of the following materials is selected: mo, ag, au, cu, ti, al, ru and Pt;
when the top electrode 107 is a multilayer structure, at least two materials are selected as follows: mo, ag, au, cu, ti, al, ru and Pt;
patterning of the top electrode 107 is accomplished sequentially by: gumming, exposing, developing, RIE or IBE, dry stripping and/or wet stripping.
And 6: opening the bottom electrode 104 until the bottom electrode 104 is exposed, and exposing the release hole opening 108 to the sacrificial layer; the opening is completed through the following steps in sequence: gumming, exposing, developing, RIE or IBE, dry stripping and/or wet stripping.
And 7: cavity 106 release is accomplished by dry etching; the etching gas is XeF2, which is in contact with the sacrificial layer through the release holes, and which chemically reacts with the sacrificial layer and does not chemically react with the bottom electrode 104, the top electrode 107, the piezoelectric layer 105, and the third substrate 103 in contact therewith.
The first substrate 101 is a silicon wafer, the second substrate 102 is a silicon wafer, the third substrate 103 is a SiO2 layer or a Si3N4 layer, the resistivity of the first substrate 101 is 50-1000 Ω · Cm, the resistivity of the second substrate 102 is 2000 Ω · Cm or more, and the resistivity of the third substrate 103 is 1010 Ω · Cm or more.
Example 2:
this embodiment will be understood by those skilled in the art as a more specific description of embodiment 1.
The embodiment provides a preparation method of a cavity of a film bulk acoustic resonator with a multilayer composite substrate, and relates to the field of resonators, in particular to the technical field of Fbar.
As shown in fig. 1, the positional relationship between the electrode boundary, the cavity boundary and the release hole is revealed. The bottom electrode outside the diagram electrode lead area 109 slightly exceeds the top electrode edge, and the projections thereof may be overlapped or retracted in this embodiment, that is, the distance between the top electrode exceeding or retracted into the bottom electrode is 0-10 um. In addition, the electrode boundaries are projected in the cavity, and the number of the release holes projected between the electrode and the cavity boundaries is not limited to the number shown in the figure.
(1) Composite substrate preparation
As shown in fig. 4, the first substrate is a silicon wafer, wherein the first substrate is a polysilicon having a high resistivity, a resistivity within 50-1000 Ω.
As shown in fig. 5, the second substrate is a silicon wafer, and is bonded with the first substrate to form a composite base; the single crystal Si film can also be grown on the first substrate through MOCVD/ALD/PECVD and other processes; the second substrate has higher resistivity relative to the first substrate, and the resistivity is more than 2000 omega.Cm; the second substrate is monocrystalline silicon, and the crystal form of the second substrate is any one of <100>, <111>, <110 >; the thickness of the second substrate is within 100-500 nm.
As shown in FIG. 6, the material of the third substrate is SiO 2 Or Si 3 N 4 SiO can be grown on the second substrate by PECVD/PVD and other processes 2 Or Si 3 N 4 A film; partial (not all and meeting the second substrate thickness requirement) second substrate Si can also form SiO through a thermal oxidation process 2 A layer; the thickness of the third substrate is within 100-500nm, and the third substrate and the sacrificial layer Si grown in the next step have very high etching selection ratio in the subsequent release process, so that the Si of the first substrate and the Si of the second substrate are protected from being damaged by etching gas; in particular, siO 2 Or Si 3 N 4 Can be as high as 10 10 And the electric energy is far beyond the Si materials of the first substrate and the second substrate, so that the electric energy leakage from a base in the subsequent device working process is effectively inhibited.
(2) Preparation of sacrificial layer
As shown in FIG. 7, the sacrificial layer is grown by using Si as a material, and the sacrificial layer is grown by MOCVD/ALD/PECVD and other processes, wherein the thickness of the sacrificial layer is within 0.5-3 um.
As shown in fig. 8, the sacrificial layer is patterned: sequentially gluing → exposing → developing → RIE or IBE → dry degumming and/or wet degumming → Plasma cleaning process, wherein the Plasma process can be applied with H 2 The plasma treatment is carried out to enable the subsequently grown film to have better grain orientation; glue application → exposure → development is a photolithographic process followed by photolithography.
(3) Bottom electrode preparation
As shown in fig. 9, the bottom electrode patterning is completed by glue application → exposure → development → RIE or IBE → dry stripping and/or wet stripping of any single layer or any combination of more than one multi-layer electrode structure of Mo/Ag/Au/Cu/Ti/Al/Ru/Pt and the like as the electrode material.
(4) Growing a piezoelectric layer
As shown in fig. 10, the piezoelectric layer is made of AlN and is grown by the Sputter process, and the AlN grown by the Sputter process can be classified into a metallic type and a toxic type, and one of the metallic type and the toxic type is selected.
(5) Top electrode preparation, similar to bottom electrode preparation, is shown in fig. 11.
(6) Bottom electrode & relief hole opening
As shown in fig. 12 and 13, the opening is completed by glue → exposure → development → RIE or IBE → dry stripping and/or wet stripping in sequence, the bottom electrode opening is exposed to the bottom electrode; the release holes are opened to expose the sacrificial layer Si. The bottom electrode opening is used for electrically connecting with other resonators or external circuits to release the hole opening so as to enable the etching gas in the next step to react with the sacrificial layer.
(7) Cavity release
As shown in fig. 14, the cavity release is completed by dry etching, wherein the etching gas is XeF2, and after contacting the sacrificial layer Si through the release holes, the chemical reaction can occur at room temperature and the chemical reaction does not occur with the contacting electrode, piezoelectric layer and third substrate SiO2 or Si3N 4. In addition, the method can effectively remove the sacrificial layer Si, and further inhibit the residual Si from causing the central frequency shift or the generation of transverse waves of the device.
The preparation method can obtain a cavity with high mechanical stability, avoid collapse or cracking of a film layer of a device in the working process, obtain a cavity almost without residues, ensure the accuracy of the characteristic frequency of the device and avoid generating unnecessary transverse modal clutter.
In the description of the present application, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the present application and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present application.
The foregoing description has described specific embodiments of the present invention. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.
Claims (10)
1. A film bulk acoustic resonator with a multilayer composite substrate, comprising a first substrate (101), a second substrate (102), a third substrate (103), a bottom electrode (104), a piezoelectric layer (105) and a top electrode (107);
the third substrate (103), the second substrate (102) and the first substrate (101) are sequentially stacked to form a composite substrate;
the bottom electrode (104) is disposed on the third substrate (103); the piezoelectric layer (105) is arranged on the bottom electrode (104), and the piezoelectric layer (105) is connected with the bottom electrode (104) and the third substrate (103);
a cavity (106) structure is formed among the third substrate (103), the bottom electrode (104) and the piezoelectric layer (105); the top electrode (107) is disposed on the piezoelectric layer (105);
the piezoelectric layer (105) is provided with a release hole opening (108), and the release hole opening (108) is communicated with the cavity (106).
2. The thin film bulk acoustic resonator with a multilayer composite substrate according to claim 1, wherein the resistivity of the first substrate (101), the second substrate (102) and the third substrate (103) is gradually increased.
3. The film bulk acoustic resonator with a multilayer composite base according to claim 2, characterized in that the first substrate (101) is a silicon wafer, the second substrate (102) is a silicon wafer, and the third substrate (103) is a SiO-substrate 2 Layer or Si 3 N 4 A layer;
the first substrate (101) has a resistivity of 50-1000 Ω & Cm, the second substrate (102) has a resistivity of 2000 Ω & Cm or more, and the third substrate (103) has a resistivity of 10 10 Omega, cm above.
4. A method for manufacturing a thin film bulk acoustic resonator with a multilayer composite substrate, which is based on the thin film bulk acoustic resonator with a multilayer composite substrate of any one of claims 1 to 3, comprising the steps of:
step 1: forming a second substrate (102) on the first substrate (101), and enabling the first substrate (101) and the second substrate (102) to form a composite base;
step 2: forming a third substrate (103) on the second substrate (102), and enabling the first substrate (101), the second substrate (102) and the third substrate (103) to form a composite base;
and 3, step 3: forming a sacrificial layer on the third substrate (103) and patterning the sacrificial layer;
and 4, step 4: forming a bottom electrode (104) on the sacrificial layer, and patterning the bottom electrode (104);
and 5: forming a piezoelectric layer (105) on the bottom electrode (104) and then forming a top electrode (107) on the piezoelectric layer (105);
and 6: opening the bottom electrode (104) until the bottom electrode (104) is exposed, and opening the release hole (108) until the sacrificial layer is exposed;
and 7: the cavity (106) release is accomplished by etching.
5. The method of manufacturing a thin film bulk acoustic resonator having a multilayer composite substrate according to claim 4, wherein in the step 1, the first substrate (101) is a silicon wafer, and the second substrate (102) is provided by any one of the following two ways:
the method I comprises the following steps: arranging a silicon wafer on the first substrate (101), wherein the silicon wafer is bonded with the first substrate (101) through silicon-silicon to form a composite base, and the silicon wafer is used as the second substrate (102);
the second method comprises the following steps: growing a single crystal Si thin film on the first substrate (101) by a MOCVD process, an ALD process, or a PECVD process, the grown single crystal Si thin film serving as the second substrate (102).
6. The method for manufacturing a thin film bulk acoustic resonator having a multilayer composite substrate according to claim 4, wherein in the step 2, the third substrate (103) is provided by any one of the following two ways:
the first method is as follows: growing SiO on the second substrate (102) by a PECVD process or a PVD process 2 Film or Si 3 N 4 Film of said SiO 2 Film or said Si 3 N 4 A thin film as the third substrate (103);
the second method comprises the following steps: forming SiO on part of the second substrate (102) by a thermal oxidation process 2 Layer of formed SiO 2 The layer serves as the third substrate (103).
7. The method for manufacturing a thin film bulk acoustic resonator having a multilayer composite substrate according to claim 4, wherein in the step 3, the sacrificial layer is grown by a MOCVD process, an ALD process or a PECVD process;
the patterning of the sacrificial layer is completed through the following steps in sequence: gluing, exposing, developing, RIE or IBE, dry degumming and/or wet degumming and Plasma cleaning;
the sacrificial layer adopts Si, and the Plasma cleaning process adopts H 2 And (4) a Plasma treatment process.
8. The method for manufacturing a thin film bulk acoustic resonator having a multilayer composite substrate according to claim 4, wherein in the step 4, the bottom electrode (104) has a single-layer structure or a multilayer structure;
when the bottom electrode (104) is of a single-layer structure, any one of the following materials is selected: mo, ag, au, cu, ti, al, ru and Pt;
when the bottom electrode (104) is of a multilayer structure, at least two materials are selected as follows: mo, ag, au, cu, ti, al, ru and Pt;
the patterning of the bottom electrode (104) is completed sequentially through the following steps: gumming, exposing, developing, RIE or IBE, dry stripping and/or wet stripping.
9. The method for manufacturing a thin film bulk acoustic resonator with a multilayer composite substrate according to claim 4, wherein in the step 5, the piezoelectric layer (105) is grown on the bottom electrode (104) by a metal type or a poisoned Sputter process by using AlN as the piezoelectric layer (105);
the top electrode (107) is of a single-layer structure or a multi-layer structure;
when the top electrode (107) is of a single-layer structure, any one of the following materials is selected: mo, ag, au, cu, ti, al, ru and Pt;
when the top electrode (107) is of a multilayer structure, at least two materials are selected from the following materials: mo, ag, au, cu, ti, al, ru and Pt;
the patterning of the top electrode (107) is accomplished sequentially by: gumming, exposing, developing, RIE or IBE, dry stripping and/or wet stripping.
10. The method for manufacturing a thin film bulk acoustic resonator having a multilayer composite substrate according to claim 4, wherein the step 6 comprises the following steps: gluing, exposing, developing, RIE or IBE, dry degumming and/or wet degumming;
in the step 7, the release of the cavity (106) is completed through dry etching, and the etching gas is XeF 2 Through the release holes (108), in contact with the sacrificial layer, chemically react with the sacrificial layer and do not contact the bottomThe electrode (104), the top electrode (107), the piezoelectric layer (105), and the third substrate (103) are chemically reacted.
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