CN115242211A - Performance improvement method of mechanical wave resonator - Google Patents
Performance improvement method of mechanical wave resonator Download PDFInfo
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- CN115242211A CN115242211A CN202210915887.1A CN202210915887A CN115242211A CN 115242211 A CN115242211 A CN 115242211A CN 202210915887 A CN202210915887 A CN 202210915887A CN 115242211 A CN115242211 A CN 115242211A
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Images
Classifications
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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
- H03H9/02007—Details of bulk acoustic wave devices
- H03H9/02086—Means for compensation or elimination of undesirable effects
- H03H9/02118—Means for compensation or elimination of undesirable effects of lateral leakage between adjacent resonators
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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
- H03H3/04—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 for obtaining desired frequency or temperature coefficient
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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
- H03H9/02007—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
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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
- H03H9/125—Driving means, e.g. electrodes, coils
- H03H9/13—Driving means, e.g. electrodes, coils for networks consisting of piezoelectric or electrostrictive materials
- H03H9/131—Driving means, e.g. electrodes, coils for networks consisting of piezoelectric or electrostrictive materials consisting of a multilayered structure
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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
- H03H9/172—Means for mounting on a substrate, i.e. means constituting the material interface confining the waves to a volume
- H03H9/173—Air-gaps
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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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- 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
- H03H2003/028—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 for obtaining desired values of other parameters
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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 discloses a method for improving the performance of a mechanical wave resonator, which comprises the following steps: s1, etching a first surface of a substrate to form a groove structure; s2, filling a sacrificial material layer in the groove structure; s3, depositing a sandwich structure above the sacrificial material layer, wherein the sandwich structure comprises a lower electrode, a piezoelectric layer and an upper electrode which are sequentially arranged from bottom to top, and the lower electrode is arranged above the sacrificial material layer; s4, carrying out structural optimization on the plane direction of the sandwich structure to inhibit transverse wave leakage and substrate leakage; s5, optimizing the connection mode of two adjacent mechanical wave resonator bodies; s6, releasing the filled sacrificial material layer to form an air cavity inside the groove structure, and forming a mechanical wave resonator body; and S7, packaging the mechanical wave resonator body. The invention inhibits transverse wave leakage and substrate leakage, improves the Q value of the mechanical wave resonator, and ensures the mechanical structure stability of the mechanical wave resonator.
Description
Technical Field
The invention relates to the technical field of processing and manufacturing of semiconductor devices, in particular to a method for improving the performance of a mechanical wave resonator.
Background
In recent years, communication technology is rapidly developed, technology updating is accelerated, particularly, 5G frequency bands are popularized, and filters required by a radio frequency front end become more and more; taking a transceiver end of a handset as an example, tens of filters are required to ensure the transmission and reception of signals. Meanwhile, the radio frequency acoustic wave duplex filter is rapidly increased in the communication market, and technologies including a Surface Acoustic Wave (SAW) device and a film bulk acoustic wave (FBAR) device are rapidly improved; the development of communication technology has increased the requirements for filters, and the requirements for large bandwidth, high power and high frequency have presented a great challenge for acoustic wave devices. The filter is required to have low insertion loss and high rectangular coefficient performance, and also has high requirements on temperature characteristics, linearity and the like.
One important factor affecting the performance of the resulting filter is the quality factor of the resonators that make up the filter. The quality factor can measure the loss of the resonator at resonance. The quality factor is high, which indicates that the loss of the resonator is smaller, and the finally formed filter has better insertion loss and passband roll-off. The film bulk acoustic wave (FBAR) filter is processed by adopting an MEMS (micro-electromechanical systems) process, and a narrow-band device with low insertion loss and high rectangular coefficient can be realized by utilizing the piezoelectric property. Another common filter is formed by an electromagnetic resonant cavity. Although the electromagnetic resonant cavity can ensure a high quality factor and achieve better filter performance, since the electromagnetic resonant cavity uses electromagnetic waves as a resonant energy carrier, the relationship between the resonant cavity size and the resonant frequency may be approximately f = v/2d at a certain frequency. Wherein v is the wave velocity, f is the resonant frequency, and d is the thickness of the resonant cavity. It can be seen that the lower the wave velocity, the smaller the medium size at the same resonance frequency; because the speed of light is far greater than the speed of sound wave, the size of the resonant cavity is very large, and the requirement for miniaturization of a communication system is difficult to meet. Therefore, the mechanical wave device is more suitable for the existing communication technology. The film bulk acoustic resonator comprises two film electrodes, a piezoelectric film layer is arranged between the two film electrodes, the working principle of the film bulk acoustic resonator is that the piezoelectric film layer generates vibration under an alternating electric field, the vibration excites bulk acoustic waves which are transmitted along the thickness direction of the piezoelectric film layer, the acoustic waves are transmitted to an interface between an upper electrode and a lower electrode and are reflected back by an air interface, and then the acoustic waves are reflected back and forth in the film, so that the acoustic waves are limited between the upper electrode and the lower electrode to form vibration. When the sound wave is transmitted in the piezoelectric film layer and is just odd times of half wavelength, standing wave oscillation is formed; thus, the Q value of resonance is reduced due to the leakage of sound waves, and the sound waves generally leak in the vertical and horizontal directions; the upper electrode and the lower electrode in the vertical direction are connected with an air boundary, and are excellent reflection boundaries, and the acoustic wave leakage from the film bulk acoustic resonator to the substrate is usually reduced by reducing the anchoring area as much as possible; however, because the piezoelectric crystal is not ideally grown along the c axis, and the resonance edge is not an infinite boundary, when excitation is applied, longitudinal waves and parasitic transverse waves in the thickness direction can be simultaneously generated at the edge, and for the transverse waves, the transverse waves can pass through the edge of the resonator to be transmitted, so that the Q value of the resonator is reduced due to the sound wave leakage caused by the propagation; some prior arts suppress the leakage of acoustic waves, can reduce the anchoring area with the substrate to avoid the energy leakage to the substrate, usually, the shape of the electrode is only one side of the electrode is kept supported at the length of the substrate, and other boundaries are suspended, but the mechanical stability of the structure is limited; the technical means is to adopt the acoustic impedance layer of the boundary frame, usually to set up the protruding or notched boundry for the electrode edge to limit the leakage of the transverse wave, for the device of different laminations, still have greater optimization space.
Disclosure of Invention
In view of the above, it is necessary to provide a method for improving the performance of a mechanical wave resonator.
A performance improvement method of a mechanical wave resonator comprises the following steps:
s1, etching a first surface of a substrate to form a groove structure;
s2, filling a sacrificial material layer in the groove structure;
s3, depositing a sandwich structure above the sacrificial material layer, wherein the sandwich structure comprises a lower electrode, a piezoelectric layer and an upper electrode which are sequentially arranged from bottom to top, and the lower electrode is arranged above the sacrificial material layer;
s4, carrying out structural optimization on the plane direction of the sandwich structure to inhibit transverse wave leakage and substrate leakage;
s5, optimizing the connection mode of two adjacent mechanical wave resonator bodies to increase the heat dissipation path and inhibit transverse waves;
s6, releasing the filled sacrificial material layer to form an air cavity inside the groove structure, and forming a mechanical wave resonator body;
and S7, packaging the mechanical wave resonator body.
In one embodiment, the step S1 includes:
s11, forming a groove structure on the first surface of the substrate through etching, and enabling the side wall of the groove structure to be an inclined plane.
In one embodiment, the step S2 includes:
s21, filling a sacrificial material layer in the groove structure;
and S22, polishing the sacrificial material layer to be level to the height of the upper surface of the substrate through a grinding and polishing technology.
In one embodiment, the step S3 includes:
s31, depositing a lower electrode above the sacrificial material layer, and patterning the lower electrode by an etching method;
s32, etching a gentle slope structure on the patterned edge of the lower electrode above the sacrificial material layer to form an inclined edge with a certain angle;
s33, depositing a piezoelectric layer on the bottom electrode;
s34, depositing an upper electrode on the piezoelectric layer and patterning;
and S35, depositing connecting metal, and connecting the upper electrode to the same height as the lower electrode.
In one embodiment, in the step S4, performing structural optimization on the sandwich structure includes: and arranging at least one transverse wave reflecting layer structure in the upper electrode, the lower electrode or the piezoelectric layer, wherein the transverse wave reflecting layer structure comprises a first frame and/or a second frame, and the first frame and the second frame are formed by adopting metal or medium deposition.
In one embodiment, in the step S4, performing structural optimization on the sandwich structure includes:
inserting a low dielectric medium between the upper electrode and the piezoelectric layer, wherein the low dielectric medium is positioned in an overlapping area of the sandwich structure and the air cavity;
or making a multi-edge cutting structure on the boundary area of the lower electrode and the piezoelectric layer which are not connected with an external circuit, so that the partial area of the piezoelectric layer exceeds the edge of the air cavity.
In one embodiment, in the step S4, performing structural optimization on the sandwich structure includes: placing a release hole of a sacrificial material layer at a zoom region of the piezoelectric layer.
In one embodiment, the step S6 includes:
s61, releasing the sacrificial material layer from the release hole by a dry method, a wet method or a dry-wet mixing method to form an air cavity in the groove structure;
s62, cleaning the air cavity to remove water vapor residues;
and S63, passivating and protecting the surface of the mechanical wave resonator body.
In one embodiment, in step S5, two mechanical wave resonator bodies are connected through a piezoelectric layer.
In one embodiment, the step S7 includes:
s71, performing injection molding on the surface of the substrate paster;
and S72, combining and packaging the mechanical wave resonator body, the IPD and the substrate.
According to the performance improvement method of the mechanical wave resonator, the high-performance mechanical wave resonator is prepared on the substrate by adopting a sacrificial material layer technology, and then the structure of the sandwich structure in the plane direction is optimized to inhibit transverse wave leakage and substrate leakage, so that the Q value of the mechanical wave resonator is improved, and the mechanical structure stability of the mechanical wave resonator is ensured; meanwhile, the mutual connection mode of the laminated layers between the mechanical wave resonator bodies is optimized, so that the heat dissipation performance of the device is improved, and the power capacity of the device is improved.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments 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 that other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a first structural optimization schematic diagram of a sandwich structure of a mechanical wave resonator of the present invention;
FIG. 2 is a schematic view of a second preferred sandwich structure according to the present invention;
FIG. 3 isbase:Sub>A cross-sectional view taken along line A-A of FIG. 2;
FIG. 4 is a schematic view of a third structural optimization of the sandwich structure of the present invention;
FIG. 5 is a schematic view of a fourth embodiment of the sandwich structure of the present invention;
FIG. 6 is a schematic view of a fifth preferred structure of the sandwich structure of the present invention;
FIG. 7 is a schematic view of a sixth preferred sandwich structure of the present invention;
FIG. 8 is a schematic view of a seventh structural optimization of the sandwich structure of the present invention;
FIG. 9 is a cross-sectional view taken along line B-B of FIG. 8;
FIG. 10 is an eighth structurally optimized schematic view of the sandwich structure of the present invention;
FIG. 11 is a cross-sectional view taken along line C-C of FIG. 10;
fig. 12 is a schematic view showing a connection state of two mechanical wave resonator bodies of the present invention;
FIG. 13 is a cross-sectional view taken along line D-D of FIG. 12;
fig. 14 is a schematic view showing a connection state of two mechanical wave resonator bodies of the present invention;
fig. 15 is a cross-sectional view taken along line E-E of fig. 14.
Detailed Description
To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
Referring to fig. 1 to 15, an embodiment of the present invention provides a method for improving performance of a mechanical wave resonator, including the steps of:
s1, etching a first surface of a substrate 1 to form a groove structure 2;
s2, filling a sacrificial material layer 3 in the groove structure 2;
s3, depositing a sandwich structure 4 above the sacrificial material layer 3, wherein the sandwich structure 4 comprises a lower electrode 41, a piezoelectric layer 42 and an upper electrode 43 which are sequentially arranged from bottom to top, and the lower electrode 41 is arranged above the sacrificial material layer 3;
s4, carrying out structural optimization on the plane direction of the sandwich structure 4 to inhibit transverse wave leakage and substrate leakage;
s5, optimizing the connection mode of two adjacent mechanical wave resonator bodies 5 to increase a heat dissipation path and inhibit transverse waves;
s6, releasing the filled sacrificial material layer 3, forming an air cavity in the groove structure 2, and forming a mechanical wave resonator body 5;
and S7, packaging the mechanical wave resonator body 5.
In this embodiment, the substrate 1 may be any suitable substrate commonly used in the art, and may be at least one of the following materials: silicon (Si) \\ silicon carbide (SiC), germanium (Ge), gallium arsenide (GaAs), indium phosphide (InP), or other group iii/v compound semiconductors, the substrate 11 requires a characteristic of high resistance, and the present invention is preferably a high-resistance silicon substrate.
In an embodiment of the present invention, the step S1 includes:
s11, forming a groove structure 2 on the first surface of the substrate 1 through etching, and enabling the side wall of the groove structure 2 to be an inclined plane. In this embodiment, the depth of the groove structure 2 is generally several micrometers, and the groove structure 2 may be formed by etching on the high-resistance silicon substrate 1 through a dry process or a wet process. While the side walls of the groove structure 12 are arranged as oblique sides (which may be trapezoidal structures), mainly to reduce the problem of stress concentration.
In an embodiment of the present invention, the step S2 includes:
s21, filling the sacrificial material layer 3 in the groove structure 2;
and S22, polishing the sacrificial material layer 3 to be flush with the height of the upper surface of the substrate 1 by a grinding and polishing technology. In this way, the surface roughness of the sacrificial material layer 14 can be ensured to be small, so as to improve the crystal quality of the subsequently deposited dielectric layer. The sacrificial material layer 3 may be made of phosphosilicate glass, low temperature silicon dioxide, borophosphosilicate glass, germanium, carbon, polyimide, or photoresist, and may be formed by a deposition process or a spin coating process according to the material.
In an embodiment of the present invention, the step S3 includes:
s31, depositing a lower electrode 41 above the sacrificial material layer 3, and patterning the lower electrode 41 by an etching method;
s32, etching the patterned edge of the lower electrode 41 above the sacrificial material layer 3 to form a slope edge with a certain angle; thus, the problem of stress concentration is avoided;
s33, depositing a piezoelectric layer 42 on the bottom electrode 41;
s34, depositing an upper electrode 43 on the piezoelectric layer 42 and patterning;
and S35, depositing a connecting metal 44, and connecting the upper electrode 43 to the same height as the lower electrode 41. In this embodiment, a thicker connection metal 44 may be deposited in a PVD/CVD or electroplating manner, and then the connection metal 44 is patterned, and only the metal of the connection portion and the metal of the area for micro-packaging are retained, and meanwhile, a portion of the metal of the connection portion for packaging is etched to form a rougher area; the connecting metal 44 may be a metal having excellent electrical conductivity, such as copper, gold, or aluminum.
In this embodiment, the bottom electrode 41 is made of a high acoustic impedance material, and may be made of metal such as molybdenum, aluminum, titanium, tungsten, gold, platinum, etc., and the deposition thickness is generally between several hundred nanometers and several micrometers. A molybdenum electrode may be preferred, and a molybdenum electrode with a certain thickness is deposited by means of PVD.
The piezoelectric layer 42 is typically aluminum nitride (AlN), zinc oxide (ZnO), lead zirconate titanate (PZT), lithium niobate (LiNbO) 3 ) Or lithium tantalate (LiTaO) 3 ) When the piezoelectric film is deposited by a PVD or CVD method, the thickness is generally about several hundred nanometers to several micrometers, the quality of the piezoelectric film crystal is better, the performance of the prepared resonator is better, and the preparation method needs to be combined with comprehensive selection such as cost efficiency.
In addition, the upper electrode 43 in this embodiment may be in the same manner as the bottom electrode 41 or may be made of a metal material with special properties, including but not limited to magnetoelectric metal, wave-absorbing metal, and the like; then, the upper electrode 43 is patterned, and the shape thereof may be circular, rectangular, or polygonal. In the present invention, the overlapping area of the upper electrode 43/the piezoelectric layer 42/the bottom electrode 41 is the resonance area, and meanwhile, it is to be noted that the anchor area (the upper electrode 43/the piezoelectric layer 42/the bottom electrode 41/the substrate 1) is reduced as much as possible, and the overlapping area can be performed in a staggered manner, or an air layer or a low dielectric material is inserted between the piezoelectric layer 42 and the electrode in the prior art, so as to avoid the leakage of energy to the substrate 1; meanwhile, the edge member of the upper electrode 43 has a frame-like structure, and lateral leakage of the acoustic wave can be avoided.
In an embodiment of the present invention, in the step S4, performing structural optimization on the sandwich structure 4 includes: at least one transverse wave reflecting layer structure is arranged in the upper electrode 43, the lower electrode 41 or the piezoelectric layer 42, the transverse wave reflecting layer structure comprises a first frame 43 and/or a second frame 44, the first frame 43 and the second frame 44 are formed by metal or medium deposition, and an impedance mismatch area is formed adjacent to the periphery.
In this embodiment, the loss change of the parallel resonance point of the mechanical wave resonator is mainly caused by acoustic energy leakage, and thus the structure of the transverse wave reflecting layer is mainly set to limit the leakage wave; as can be seen by the dispersion curve of the stack; multiple waves can be allowed to exist at the parallel resonance frequency, and the main energy loss at the parallel resonance point is leakage of an S1 mode lamb and an A1 mode lamb; corresponding shear wave reflecting layer structures may be employed to limit leakage of lambs, typically 1/4 wavelength wide impedance high-low crossover layers, one or more of which may be provided. In the present invention, the first frame 43 is provided for suppressing the S1 mode lamb, and the second frame 44 is provided for suppressing the A1 mode lamb.
In the invention, the conventional mechanical wave resonator is in a sandwich structure and is larger than an air cavity area, acoustic waves are scattered at the edge to form transverse waves and longitudinal waves, energy can be transmitted to the substrate 1 and cannot return, and then energy leakage is generated; to optimize the connection structure, the overlapping area of the sandwich structure 4 and the substrate 1 is minimized. Referring to FIGS. 2-3, in one embodiment of the present invention, the other boundary of the sandwich structure 4 is configured to be smaller than the air cavity, only the boundary that needs to be connected to other circuits is configured to be larger than the air cavity.
Referring to fig. 4-11, in another embodiment of the present invention, the step S4 of optimizing the structure of the sandwich structure 4 includes:
a low dielectric medium is inserted between the upper electrode 43 and the piezoelectric layer 42, and the low dielectric medium is positioned in an overlapping area of the sandwich structure 4 and the air cavity; thus, the partial pressure energy of the piezoelectric layer 42 is made smaller, reducing the energy leakage to the substrate 1;
or the boundary area of the lower electrode 41 and the piezoelectric layer 42 which are not connected with an external circuit is made into a multi-edge cutting structure, so that the partial area of the piezoelectric layer 42 exceeds the edge of the air cavity, an acute angle structure is avoided, the problem of stress concentration is reduced, the leakage of energy to the substrate 1 is reduced, the stability of a mechanical structure is improved, and the device can be suitable for more complex environments. In this embodiment, different patterns of piezoelectric layers 42 may be provided, such as: polygonal or arc-shaped, etc., so that the partial area of the piezoelectric layer 42 is larger than the air cavity (keeping the stability of the mechanical structure of the device), when cascading with other resonator bodies, the overlapping area of the connection area and the substrate 1 can be relatively reduced, and the leakage of the acoustic wave is avoided.
Referring to fig. 7, in another embodiment of the present invention, in the step S4, the structural optimization of the sandwich structure includes: the relief holes 6 of the layer of sacrificial material 3 are placed in the scaled area of said piezoelectric layer 42. Therefore, the space occupancy rate can be reduced, and the layout effect is improved. It should be noted that the above-mentioned optimized structures can be used in combination, and are not described herein again.
In an embodiment of the present invention, the step S6 includes:
s61, releasing the sacrificial material layer 3 from the release hole 6 by a dry method, a wet method or a dry-wet mixing method, so that an air cavity is formed inside the groove structure 2;
s62, cleaning the air cavity to remove water vapor residues;
and S63, carrying out passivation protection treatment on the surface of the mechanical wave resonator body 5.
In this embodiment, the filled sacrificial material layer 3 is released, and an energy reflection interface of the mechanical wave resonator is formed in the air cavity; the release is carried out through the release holes on the surface, and can be carried out by a dry method, a wet method or a dry-wet mixed method so as to ensure the completeness of the release, and meanwhile, a subsequent cleaning process is required to avoid water vapor and the like caused by the release process, so that the cleanliness of the air cavity is ensured; in one embodiment, the mechanical wave resonator body 5 is passivated after the process is completed to prevent contamination of the external environment.
Referring to fig. 12 to 15, in an embodiment of the present invention, in the step S5, two mechanical wave resonator bodies 5 are connected through a piezoelectric layer 42. In this way, the heat dissipation path can be increased relatively, in particular in connection with the resonator close to the output and in connection with the resonator connected to ground. When the piezoelectric layer 42 is AlN, the excellent thermal conductivity thereof can increase the heat dissipation path, thereby improving the withstand power of the device; in some embodiments, the piezoelectric layer 42 is patterned to optimize the structure, so that the suppression of transverse waves can be increased, and the Q value of the device can be ensured while the heat dissipation performance of the device is improved.
In an embodiment of the present invention, the step S7 includes:
s71, performing injection molding on the surface of the substrate paster;
and S72, combining and packaging the mechanical wave resonator body, the IPD and the substrate.
In conclusion, the invention has the advantages that:
by adopting a sacrificial material layer technology, a high-performance mechanical wave resonator is prepared on the substrate 1, and then the structure of the sandwich structure 4 in the plane direction is optimized to inhibit transverse wave leakage and substrate leakage, improve the Q value of the mechanical wave resonator and ensure the mechanical structure stability of the mechanical wave resonator; meanwhile, the mutual connection mode of the lamination layers between the mechanical wave resonator bodies 5 is optimized, so that the heat dissipation performance of the device is improved, and the power capacity of the device is improved.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above examples are only illustrative of several embodiments of the present invention, but should not be construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A method for improving the performance of a mechanical wave resonator, comprising the steps of:
s1, etching a first surface of a substrate to form a groove structure;
s2, filling a sacrificial material layer in the groove structure;
s3, depositing a sandwich structure above the sacrificial material layer, wherein the sandwich structure comprises a lower electrode, a piezoelectric layer and an upper electrode which are sequentially arranged from bottom to top, and the lower electrode is arranged above the sacrificial material layer;
s4, carrying out structural optimization on the plane direction of the sandwich structure to inhibit transverse wave leakage and substrate leakage;
s5, optimizing the connection mode of two adjacent mechanical wave resonator bodies to increase the heat dissipation path and inhibit transverse waves;
s6, releasing the filled sacrificial material layer to form an air cavity inside the groove structure, and forming a mechanical wave resonator body;
and S7, packaging the mechanical wave resonator body.
2. The method for improving the performance of the mechanical wave resonator according to claim 1, wherein the step S1 includes:
s11, forming a groove structure on the first surface of the substrate through etching, and enabling the side wall of the groove structure to be an inclined plane.
3. The method for improving the performance of the mechanical wave resonator according to claim 2, wherein the step S2 includes:
s21, filling a sacrificial material layer in the groove structure;
and S22, polishing the sacrificial material layer to be flush with the height of the upper surface of the substrate by a grinding and polishing technology.
4. The method for improving performance of a mechanical wave resonator according to claim 1, wherein the step S3 includes:
s31, depositing a lower electrode above the sacrificial material layer, and patterning the lower electrode by an etching method;
s32, etching the patterned edge of the lower electrode above the sacrificial material layer to form a slope edge with a certain angle;
s33, depositing a piezoelectric layer on the bottom electrode;
s34, depositing an upper electrode on the piezoelectric layer and patterning;
and S35, depositing connecting metal, and connecting the upper electrode to the same height as the lower electrode.
5. The method for improving the performance of the mechanical wave resonator according to claim 4, wherein in the step S4, the structural optimization of the sandwich structure includes: and arranging at least one transverse wave reflecting layer structure in the upper electrode, the lower electrode or the piezoelectric layer, wherein the transverse wave reflecting layer structure comprises a first frame and/or a second frame, and the first frame and the second frame are formed by adopting metal or medium deposition.
6. The method for improving the performance of the mechanical wave resonator according to claim 4, wherein in the step S4, the structural optimization of the sandwich structure includes:
inserting a low dielectric medium between the upper electrode and the piezoelectric layer, wherein the low dielectric medium is positioned in an overlapping area of the sandwich structure and the air cavity;
or making a multi-edge cutting structure on the boundary area of the lower electrode and the piezoelectric layer which are not connected with an external circuit, so that a partial area of the piezoelectric layer exceeds the edge of the air cavity.
7. The method for improving performance of a mechanical wave resonator according to claim 4, wherein in step S4, performing structural optimization on the sandwich structure includes: placing a relief hole of a layer of sacrificial material over a scaled region of the piezoelectric layer.
8. The method for improving performance of a mechanical wave resonator according to claim 1, wherein the step S6 includes:
s61, releasing the sacrificial material layer from the release hole by a dry method, a wet method or a dry-wet mixing method to form an air cavity in the groove structure;
s62, cleaning the air cavity to remove water vapor residues;
and S63, passivating and protecting the surface of the mechanical wave resonator body.
9. The method for improving the performance of the mechanical wave resonator according to claim 1, wherein in step S5, the two mechanical wave resonator bodies are connected by a piezoelectric layer.
10. The method for improving performance of a mechanical wave resonator according to claim 1, wherein the step S7 includes:
s71, performing injection molding on the surface of the substrate paster;
and S72, combining and packaging the mechanical wave resonator body, the IPD and the substrate.
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