CN111200411A - Micromechanical piezoelectric disc resonator and manufacturing method thereof - Google Patents
Micromechanical piezoelectric disc resonator and manufacturing method thereof Download PDFInfo
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
- H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
- H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/15—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
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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
- H03H2003/027—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 microelectro-mechanical [MEMS] type
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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
- H03H2009/155—Constructional features of resonators consisting of piezoelectric or electrostrictive material using MEMS techniques
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Abstract
The invention provides a micromechanical piezoelectric disc resonator, which comprises a piezoelectric device and a bottom supporting structure, wherein the piezoelectric device comprises a top input electrode, a bottom grounding electrode and a piezoelectric vibration layer arranged between the top input electrode and the bottom grounding electrode; the bottom support structure comprises a substrate and a support anchor fixed between the central position of the bottom grounding electrode and the substrate, wherein the support anchor is made of a material selected from low-resistance silicon. The invention optimizes the anchor point design, changes the traditional lateral support structure into the central support, has smaller anchor point loss and higher quality factor, and has more excellent device performance. Based on the disk resonator, the invention also provides a manufacturing method of the disk resonator.
Description
Technical Field
The invention relates to the technical field of micromechanical resonators, in particular to a micromechanical piezoelectric disc resonator and a manufacturing method thereof.
Background
The clock chip is used as a time reference source in the circuit system and plays an important role in the circuit system. The traditional clock chip generally adopts a quartz crystal oscillator as a resonator to generate signal waveforms, but the volume of the quartz crystal oscillator is difficult to reduce, and the miniaturization of a circuit system is hindered by the larger volume. In recent years, due to the progress of micromachining technology, MEMS resonators have been developed, which have advantages of small size, low power consumption, low cost, compatibility with cmos (complementary metal oxide semiconductor integrated circuit) processes, and the like. The micromechanical disc resonator is a radio frequency resonator developed in recent years, and compared with other radio frequency resonators, the micromechanical disc resonator has a high quality factor (Q), and meets the requirements of mobile communication mobile phones, internet wireless access systems, Bluetooth systems and the like at present.
The quality factor (Q) of the resonator is one of the most important parameters reflecting the characteristics of the resonator, and a high quality factor means that the device has small insertion loss, low energy consumption, low phase noise, narrow bandwidth, large resonance amplitude, good resonance circuit selectivity and the like, and can improve the performance such as frequency modulation range, power consumption, linearity and the like, and how to obtain a high Q value>103) Resonant devices have long been a focus of frequency reference component research. Therefore, how to optimize the device structure to obtain a high quality factor is a problem that needs to be solved.
Disclosure of Invention
The invention provides a micromechanical piezoelectric disk resonator aiming at least one of the problems of the traditional piezoelectric disk resonator.
In one aspect, the present invention provides a micromechanical piezoelectric disk resonator comprising: a piezoelectric device and a bottom supporting structure,
the piezoelectric device comprises a top input electrode, a bottom grounding electrode and a piezoelectric vibration layer arranged between the top input electrode and the bottom grounding electrode;
the bottom support structure comprises a substrate and a support anchor fixed between the central position of the bottom grounding electrode and the substrate, wherein the support anchor is made of a material selected from low-resistance silicon.
The micromechanical piezoelectric disc resonator structure provided by the invention optimizes anchor point design, changes the traditional lateral support structure into a central support, overcomes the defects existing in the traditional MEMS resonator compared with the traditional structure, and has the advantages of smaller anchor point loss, higher quality factor and more excellent device performance. And provides a foundation for manufacturing the SOI wafer.
In some embodiments, the support anchor is a cylinder, the radius of the support anchor is 3 μm, the height of the support anchor is 1um, the piezoelectric device is a disk, the radius of the piezoelectric vibration layer is 30um, the thickness of the piezoelectric vibration layer is 1um, and the thickness of the metal electrodes of the top input electrode and the bottom grounding electrode is 100 nm.
In some embodiments, the top input electrode material is gold or molybdenum, the bottom ground electrode material is gold or molybdenum, and the piezoelectric vibration layer material is aluminum nitride.
In some embodiments, the bottom support structure is an SOI substrate with a top layer of low resistivity silicon layer, a middle layer of oxide layer, a bottom layer of high resistivity silicon layer, and the anchor is part of the low resistivity silicon layer.
On the other hand, the invention provides a manufacturing method of a micro-mechanical piezoelectric disc resonator, which comprises the following steps:
and 7, etching the first silicon dioxide sacrificial layer and the second silicon dioxide sacrificial layer to release the device.
According to the manufacturing method of the micromechanical piezoelectric disc resonator, the MEMS resonator is manufactured by adopting the SOI substrate, so that the intrinsic loss of materials can be reduced, the defect that a thicker film cannot be grown by CVD (chemical vapor deposition) is overcome, the complexity of the process can be greatly reduced, and the cost is reduced. The low-cost batch production of the high-performance product provided by the invention becomes possible.
In some embodiments, step 2, growing a first silicon dioxide sacrificial layer by PECVD and polishing by CMP until the support anchors are exposed; and 5, growing a second silicon dioxide sacrificial layer by utilizing PECVD (plasma enhanced chemical vapor deposition), and grinding the second silicon dioxide sacrificial layer by utilizing a CMP (chemical mechanical polishing) process until the aluminum nitride layer is exposed.
In some embodiments, step 3 deposits a gold film by sputtering and produces a bottom ground electrode by a lift-off process; and 6, depositing a gold film by sputtering, and manufacturing a bottom and top signal input electrode by a stripping process.
In some embodiments, step 4 deposits an aluminum nitride film by sputtering, shapes the piezoelectric vibration layer by dry etching, and etches to form a via into the bottom ground electrode.
In some embodiments, step 7 etches the first and second sacrificial layers of silicon dioxide using hydrofluoric acid gas to release the device.
Drawings
In order to more clearly illustrate the technical solution of the present invention, the drawings needed for the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
Fig. 1 is a three-dimensional structural diagram of a micromechanical piezoelectric disk resonator according to the present invention;
fig. 2(a) is a cross-sectional view of a lateral three-dimensional structure of a micro-mechanical piezoelectric disk resonator provided in the present invention;
fig. 2(b) is a cross-sectional view of a longitudinal three-dimensional structure of a micro-mechanical piezoelectric disk resonator provided in the present invention;
fig. 3(a) is a schematic diagram of a transverse cross-sectional structure processed in step 1 of a method for manufacturing a micromechanical piezoelectric disk resonator according to an embodiment of the present invention;
fig. 3(b) is a schematic longitudinal cross-sectional structure diagram processed in step 1 of a method for manufacturing a micromechanical piezoelectric disk resonator according to an embodiment of the present invention;
fig. 4(a) is a schematic diagram of a lateral cross-sectional structure processed in step 2 of a method for manufacturing a micromechanical piezoelectric disk resonator according to an embodiment of the present invention;
fig. 4(b) is a schematic longitudinal cross-sectional structure diagram processed in step 2 of a method for manufacturing a micromechanical piezoelectric disk resonator according to an embodiment of the present invention;
fig. 5(a) is a schematic diagram of a lateral cross-sectional structure processed in step 3 of a method for manufacturing a micromechanical piezoelectric disk resonator according to an embodiment of the present invention;
fig. 5(b) is a schematic longitudinal cross-sectional structure diagram processed in step 3 of a method for manufacturing a micromechanical piezoelectric disk resonator according to an embodiment of the present invention;
fig. 6(a) is a schematic diagram of a lateral cross-sectional structure of a micromechanical piezoelectric disk resonator after being processed in step 4 of a method for manufacturing a micromechanical piezoelectric disk resonator according to an embodiment of the present invention;
fig. 6(b) is a schematic longitudinal cross-sectional structure diagram processed in step 4 of a method for manufacturing a micromechanical piezoelectric disk resonator according to an embodiment of the present invention;
fig. 7(a) is a schematic diagram of a lateral cross-sectional structure of a micromechanical piezoelectric disk resonator after being processed in step 5 of a method for manufacturing a micromechanical piezoelectric disk resonator according to an embodiment of the present invention;
fig. 7(b) is a schematic longitudinal cross-sectional structure diagram processed in step 5 of a method for manufacturing a micromechanical piezoelectric disk resonator according to an embodiment of the present invention;
fig. 8(a) is a schematic diagram of a lateral cross-sectional structure processed in step 6 of a method for manufacturing a micromechanical piezoelectric disk resonator according to an embodiment of the present invention;
fig. 8(b) is a schematic longitudinal cross-sectional structure diagram processed in step 6 of a method for manufacturing a micromechanical piezoelectric disk resonator according to an embodiment of the present invention;
fig. 9(a) is a schematic diagram of a lateral cross-sectional structure of a micromechanical piezoelectric disk resonator after being processed in step 7 of a method for manufacturing a micromechanical piezoelectric disk resonator according to an embodiment of the present invention;
fig. 9(b) is a schematic longitudinal cross-sectional structure diagram processed in step 7 of a method for manufacturing a micromechanical piezoelectric disk resonator according to an embodiment of the present invention;
FIG. 10 is a simulation comparison of lateral support and center support of a micromachined piezoelectric disk resonator according to an embodiment of the present invention;
FIG. 11 is a simulated comparison of different anchor sizes for a micromechanical piezoelectric disk resonator according to an embodiment of the present invention;
fig. 12 is a graph illustrating changes in radial displacement of a disk of a micromechanical piezoelectric disk resonator according to an embodiment of the present invention.
Detailed Description
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, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without any inventive step, are within the scope of the present invention.
In the present invention, a "substrate" refers to a base for a transistor or an integrated circuit, and the substrate not only plays a role of electrical performance, but also plays a role of mechanical support.
In the present invention, "SOI" refers to Silicon-On-Insulator, i.e., Silicon On an insulating substrate, which introduces a buried oxide layer between the top Silicon and the backing substrate.
In the present invention, "low-resistance silicon" means special silicon made of a silicon material of low resistance, and the resistivity of the low-resistance silicon is less than 0.01 Ω & cm.
In the present invention, "high resistivity silicon" means special silicon made of silicon material with low resistance, and the resistivity of high resistivity silicon is more than 1000 Ω & cm.
In the present invention, "etching" refers to a process of selectively removing unwanted material from the surface of a substrate by chemical or physical means.
In the present invention, "dry etching" means etching away exposed surface materials on a substrate by physically and chemically reacting the substrate exposed to plasma through a mask window opened by photolithography using plasma generated in a gas state.
In the present invention, "PECVD" means that a gas containing film-forming atoms is ionized by microwave or radio frequency to locally form plasma, and the plasma is chemically very reactive and easily reacts to deposit a desired film on a substrate.
In the present invention, "CMP" refers to chemical mechanical polishing, which is a process technique based on a combination of chemical etching and mechanical removal.
In the present invention, "sputter deposition" refers to a method of forming a thin film on a substrate surface by bombarding a target with energetic particles to sputter atoms in the target.
In the present invention, the "stripping process" means that after a substrate is coated with a photoresist, exposed and developed, a photoresist film having a certain pattern is used as a mask, a strip is applied to evaporate a desired metal, and then the photoresist is removed while the metal on the photoresist film is stripped off, so that only the metal originally patterned remains on the substrate.
In the present invention, "patterning" refers to generating a regular surface structure in a nanometer scale in at least one dimension, and the patterning may be achieved by various techniques, such as photolithography, a scanning probe-based micro-mechanical method (micromachining), micro-contact Printing (microcontact Printing), and the like.
As shown in fig. 1, 2(a) and 2(b), the present invention provides a micromechanical piezoelectric disc resonator comprising: a piezoelectric device and a bottom supporting structure,
the piezoelectric device comprises a top input electrode 8, a bottom grounding electrode 1 and a piezoelectric vibration layer 5 arranged between the top input electrode 8 and the bottom grounding electrode 1;
the bottom supporting structure comprises a substrate and a supporting anchor 6 fixed between the bottom center position of the bottom grounding electrode 1 and the substrate, wherein the supporting anchor is 6 materials selected from low-resistance silicon.
The micromechanical piezoelectric disc resonator structure provided by the invention optimizes anchor point design, changes the traditional lateral support structure into a central support, overcomes the defects existing in the traditional MEMS resonator compared with the traditional structure, and has the advantages of smaller anchor point loss, higher quality factor and more excellent device performance. And provides a foundation for manufacturing the SOI wafer.
Through long-term research, the applicant finds that energy loss caused by the support anchor is one of important factors influencing the quality factor of the resonator, and large anchor point loss can reduce the quality factor of a device. Compared with the traditional piezoelectric resonator, the supporting anchor is generally arranged on two sides of the disk, and the amplitude of the radial disk under the radial free vibration mode is gradually increased, so that larger anchor point loss is caused. Accordingly, applicants provide the optimized device structure of the present invention that significantly improves the reduction in the resonator quality factor due to anchor point loss. According to the center support scheme provided by the invention, the anchor point is positioned at the node of the oscillator, so that the energy loss caused by the anchor point can be greatly reduced, the anchor point design is optimized, and the high-performance disc-type piezoelectric resonator is realized.
In various embodiments of the micromechanical piezoelectric disk resonator provided by the invention, the bottom support structure is preferably an SOI substrate, the top layer of the SOI substrate is a low-resistance silicon layer 2, the middle layer is an oxide layer 3, the bottom layer is a high-resistance silicon layer 4, and the support anchor 6 is a part of the low-resistance silicon layer 2
Meanwhile, the micromechanical piezoelectric disc resonator structure provided by the invention is suitable for being manufactured by adopting an SOI (silicon on insulator) sheet, so that the intrinsic loss of materials can be reduced, the defect that a thicker film cannot be grown by CVD (chemical vapor deposition) is overcome, the complexity of the process can be greatly reduced, and the cost is reduced.
In another aspect, the present invention provides a method for manufacturing the above micromechanical piezoelectric disk resonator, including the following steps:
According to the manufacturing method of the micromechanical piezoelectric disc resonator, the MEMS resonator is manufactured by adopting the SOI substrate, so that the intrinsic loss of materials can be reduced, the defect that a thicker film cannot be grown by CVD (chemical vapor deposition) is overcome, the complexity of the process can be greatly reduced, and the cost is reduced. The low-cost batch production of the high-performance product provided by the invention becomes possible.
In various embodiments of the manufacturing method provided by the present invention, preferably, in step 2, the first sacrificial silicon dioxide layer 9 is grown by PECVD and polished by a CMP process until the support anchor 6 is exposed; and 5, growing a second silicon dioxide sacrificial layer 9 by PECVD (plasma enhanced chemical vapor deposition), and grinding the sacrificial layer by a CMP (chemical mechanical polishing) process until the aluminum nitride layer is exposed.
In various embodiments of the manufacturing method provided by the present invention, it is preferable that step 3 is to deposit a gold thin film by sputtering, and to manufacture the bottom ground electrode 1 by a lift-off process; and 6, depositing a gold film by sputtering, and manufacturing a bottom and top signal input electrode 8 by a stripping process.
In various embodiments of the manufacturing method provided by the present invention, it is preferable that step 4 deposit an aluminum nitride film by sputtering, determine the shape of the piezoelectric vibration layer 5 by dry etching, and etch to form a through hole into the bottom ground electrode 1.
In various embodiments of the method of manufacturing according to the present invention, it is preferred that step 7 utilizes hydrofluoric acid HF gas to etch first sacrificial layer of silicon dioxide 9 and second sacrificial layer of silicon dioxide 9 to release the device.
According to the manufacturing method of the micromechanical piezoelectric disc resonator, the device structure is etched by the dry method, the HF gas is used for releasing the device, the device is released when the device structure is manufactured, the problem of device failure caused by adhesion of the structural layer and the substrate layer does not exist, the process complexity is reduced, and the yield is improved.
Method example 1:
the embodiment provides a manufacturing method of a micro-mechanical piezoelectric disk resonator, which comprises the following steps:
as shown in fig. 3(a) and 3(b), step 1, dry etching a preset area around the center of the low-resistivity silicon 2 on the top layer of the SOI substrate to form a cavity 7 for releasing the piezoelectric device and simultaneously form a support anchor 6 at the center of the substrate;
as shown in fig. 4(a) and 4(b), step 2, growing a first sacrificial layer 9 of silicon dioxide on the surface of the cavity 7 by PECVD, and grinding the grown first sacrificial layer 9 of silicon dioxide by CMP until the support anchors 6 expose the upper surface of the first sacrificial layer 9 of silicon dioxide;
as shown in fig. 5(a) and 5(b), step 3, sputtering a gold thin film on the upper surface of the first sacrificial silicon dioxide layer 9 on top of the substrate with the support anchor 6 as the center and patterning the gold thin film by a lift-off process to form a bottom ground electrode 1 with a predetermined shape;
as shown in fig. 6(a) and 6(b), step 4, sputtering and depositing an aluminum nitride layer, and dry etching and patterning to obtain a piezoelectric vibration layer 5 with a preset shape and expose a terminal area at the end of the bottom ground electrode 1;
as shown in fig. 7(a) and 7(b), step 5, growing a second sacrificial layer 9 of silicon dioxide on the top of the etched substrate by PECVD, and polishing and leveling the sacrificial layer by CMP until the upper surface of the piezoelectric vibration layer 5 is exposed;
as shown in fig. 8(a) and 8(b), step 6, sputter-depositing a metal layer on the second sacrificial silicon dioxide layer 9 and the piezoelectric vibration layer 5 and patterning the metal layer by a lift-off process to form a top input electrode 8;
as shown in fig. 9(a) and 9(b), first sacrificial layer 9 of silicon dioxide and second sacrificial layer 9 of silicon dioxide are etched with hydrofluoric acid (HF) gas to release the device, step 7.
Product example 1:
in one embodiment of the micromechanical piezoelectric disc resonator provided by the invention, the support anchor 6 is preferably a cylinder, the radius of the support anchor 6 is 3 μm, the height of the support anchor is 1um, the piezoelectric device is disc-shaped, the radius of the piezoelectric vibration layer 5 is 30um, the thickness of the piezoelectric vibration layer is 1um, and the thicknesses of the metal electrodes of the top input electrode 8 and the bottom grounding electrode 1 are 100 nm; the top input electrode 8 is made of gold or molybdenum, the bottom grounding electrode 1 is made of gold or molybdenum, and the piezoelectric vibration layer 5 is made of aluminum nitride.
The position and the size of the support anchor of the micromechanical piezoelectric disc resonator have direct influence on the performance of the resonator, and the invention also provides an optimized anchor point design structure so as to optimize the performance and improve the quality factor of the micromechanical piezoelectric disc resonator.
The above product example 1 and the prior comparative example 1 are compared and studied by COMSOL Multiphysics simulation analysis software to show the influence of the design of the support anchor position of the micromechanical piezoelectric disc resonator provided by the invention on the quality factor of the resonator.
Product comparative example 1: piezoelectric resonator adopts the side direction support mode, and the under bracing anchor width sets up to 8um, and length is 16 um.
Using COMSOL Multiphysics simulation analysis software, fig. 10 is a comparison of the admittance plots of the lateral support of comparative example 1 and the center support of product example 1, and unexpectedly findings were studied for the quality factor (Q value) of the resonator for example 1 and comparative example 1; the center-supported resonator quality factor (Q-value) of product example 1 is about 3162, compared to the resonator quality factor (Q-value) of comparative example 1 for the lateral support scheme, which is about 1609, which is a significant improvement of nearly one-fold.
And comparing and researching the product embodiment 1 and the product embodiments 2-4 by simulation analysis software COMSOL Multiphysics to show the influence of the size design of the support anchor of the micromechanical piezoelectric disc resonator provided by the invention on the quality factor of the resonator.
Product examples 2 to 4: the remaining parameters were the same as in example 1, wherein the radii of the cylindrical support anchors were 1 μm, 4 μm and 5 μm, respectively.
The resonator center frequencies and quality factors (Q values) of examples 1 to 4 were investigated using a simulation analysis software COMSOL Multiphysics to obtain admittance chart comparisons for different support anchor sizes as shown in fig. 11.
As shown in table 1, as the anchor point size increases, the center frequency increases from 82.1MHz to 82.5MHz, but the amplitude decreases by approximately 50%, which corresponds to a Q value that also decreases from 4321 to 1130. This is because the disk has a central amplitude of 0 in the radial free vibration mode and an amplitude of gradually increasing in the radial direction, as shown in fig. 12. As the anchor radius increases, its anchor loss also gradually increases, resulting in a decrease in Q. The size of the support anchor should be reduced as much as possible under existing process conditions.
The radius of the support part in the product example 1 is 3um, which is an optimal value, by comprehensively considering various factors.
TABLE 1
| Radius of anchor (mum) | 1 | 3 | 4 | 5 |
| f0(MHz) | 82.1 | 82.2 | 82.3 | 82.5 |
| Quality factor (Q) | 4321 | 3162 | 2743 | 1130 |
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention, and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (9)
1. A micromachined piezoelectric disc resonator, comprising: a piezoelectric device and a bottom supporting structure,
the piezoelectric device comprises a top input electrode (8), a bottom grounding electrode (1) and a piezoelectric vibration layer (5) arranged between the top input electrode (8) and the bottom grounding electrode (1);
the bottom supporting structure comprises a substrate and a supporting anchor (6) fixed between the bottom center of the bottom grounding electrode (1) and the substrate, wherein the supporting anchor is made of (6) materials selected from low-resistance silicon.
2. A micromechanical piezoelectric disc resonator according to claim 1, characterized in that the supporting anchor (6) is a cylinder, the radius of the supporting anchor (6) is 3 μm, the supporting anchor height is 1um, the piezoelectric device is a disc, the radius of the piezoelectric vibrating layer (5) is 30um, the thickness is 1um, and the metal electrode thickness of the top input electrode (8) and the bottom grounding electrode (1) are both 100 nm.
3. A micromechanical piezoelectric disc resonator according to claim 2, characterized in that the top input electrode (8) is made of gold or molybdenum, the bottom ground electrode (1) is made of gold or molybdenum, and the piezoelectric vibration layer (5) is made of aluminum nitride.
4. A micromechanical piezoelectric disc resonator according to claim 1, characterized in that said bottom support structure is a SOI substrate, the top layer of said SOI substrate is a low-resistance silicon layer (2), the middle layer is an oxide layer (3), the bottom layer is a high-resistance silicon layer (4), and said support anchor (6) is part of said low-resistance silicon layer (2).
5. The method for manufacturing the micromechanical piezoelectric disk resonator according to any one of claims 1 to 4, comprising the steps of:
step 1, dry etching a preset area around the center of a low-resistance silicon (2) on the top layer of an SOI substrate to form a concave cavity (7) for releasing a piezoelectric device and simultaneously form a support anchor (6) positioned in the center of the substrate;
step 2, growing a first silicon dioxide sacrificial layer (9) on the surface of the concave cavity (7), and grinding the grown first silicon dioxide sacrificial layer (9) until the support anchor (6) exposes the upper surface of the first silicon dioxide sacrificial layer (9);
step 3, depositing a metal layer on the upper surface of the first silicon dioxide sacrificial layer (9) on the top of the substrate by taking the support anchor (6) as a center and patterning to manufacture a bottom grounding electrode (1) in a preset shape;
step 4, depositing an aluminum nitride layer, and carrying out dry etching patterning to obtain a piezoelectric vibration layer (5) with a preset shape and expose a wiring area at the end part of the bottom grounding electrode (1);
step 5, growing a second silicon dioxide sacrifice layer (9) on the etched top, and grinding the silicon dioxide sacrifice layer until the upper surface of the piezoelectric vibration layer (5) is exposed;
step 6, depositing a metal layer on the second silicon dioxide sacrificial layer (9) and the upper surface of the piezoelectric vibration layer (5) and patterning to form a top input electrode (8);
and 7, etching the first silicon dioxide sacrificial layer (9) and the second silicon dioxide sacrificial layer (9) to release the device.
6. The method for manufacturing the micromechanical piezoelectric disk resonator according to claim 5, wherein the step 2 comprises growing the first sacrificial silicon dioxide layer (9) by PECVD and polishing the sacrificial silicon dioxide layer by CMP until the supporting anchor (6) is exposed; and 5, growing a second silicon dioxide sacrificial layer (9) by utilizing PECVD (plasma enhanced chemical vapor deposition), and grinding the sacrificial layer by utilizing a CMP (chemical mechanical polishing) process until the aluminum nitride layer is exposed.
7. The method for manufacturing a micromechanical piezoelectric disc resonator according to claim 5, wherein the step 3 is to deposit a gold film by sputtering and manufacture the bottom ground electrode (1) by a lift-off process; and 6, depositing a gold film by sputtering, and manufacturing a bottom and top signal input electrode (8) by a stripping process.
8. The method for manufacturing a micromechanical piezoelectric disc resonator according to claim 5, wherein the step 4 comprises depositing an aluminum nitride film by sputtering, determining the shape of the piezoelectric vibration layer (5) by dry etching, and etching to form a through hole into the bottom ground electrode (1).
9. A method for fabricating a micromechanical piezoelectric disc resonator according to claim 5, characterized in that step 7 uses hydrofluoric acid (HF) gas to etch the first sacrificial layer of silicon dioxide (9) and the second sacrificial layer of silicon dioxide (9) to release the device.
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