CN116865704A - Surface acoustic wave filter structure and preparation method thereof - Google Patents
Surface acoustic wave filter structure and preparation method thereof Download PDFInfo
- Publication number
- CN116865704A CN116865704A CN202310864870.2A CN202310864870A CN116865704A CN 116865704 A CN116865704 A CN 116865704A CN 202310864870 A CN202310864870 A CN 202310864870A CN 116865704 A CN116865704 A CN 116865704A
- Authority
- CN
- China
- Prior art keywords
- acoustic wave
- wave filter
- filter structure
- layer
- surface acoustic
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000010897 surface acoustic wave method Methods 0.000 title claims abstract description 37
- 238000002360 preparation method Methods 0.000 title abstract description 7
- 238000005516 engineering process Methods 0.000 claims abstract description 26
- 239000010408 film Substances 0.000 claims description 39
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 34
- 239000000758 substrate Substances 0.000 claims description 29
- WSMQKESQZFQMFW-UHFFFAOYSA-N 5-methyl-pyrazole-3-carboxylic acid Chemical compound CC1=CC(C(O)=O)=NN1 WSMQKESQZFQMFW-UHFFFAOYSA-N 0.000 claims description 26
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 claims description 26
- 238000000034 method Methods 0.000 claims description 20
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims description 18
- 229910010271 silicon carbide Inorganic materials 0.000 claims description 17
- 239000000377 silicon dioxide Substances 0.000 claims description 17
- 235000012239 silicon dioxide Nutrition 0.000 claims description 17
- 239000000463 material Substances 0.000 claims description 15
- 229910021421 monocrystalline silicon Inorganic materials 0.000 claims description 13
- 230000008569 process Effects 0.000 claims description 11
- 239000010949 copper Substances 0.000 claims description 10
- 238000000151 deposition Methods 0.000 claims description 10
- 238000005498 polishing Methods 0.000 claims description 10
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 9
- 229910052802 copper Inorganic materials 0.000 claims description 9
- 238000004519 manufacturing process Methods 0.000 claims description 9
- 230000004913 activation Effects 0.000 claims description 7
- WPPDFTBPZNZZRP-UHFFFAOYSA-N aluminum copper Chemical compound [Al].[Cu] WPPDFTBPZNZZRP-UHFFFAOYSA-N 0.000 claims description 7
- 238000005477 sputtering target Methods 0.000 claims description 7
- 229910000881 Cu alloy Inorganic materials 0.000 claims description 6
- 229910052782 aluminium Inorganic materials 0.000 claims description 6
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 6
- 239000002131 composite material Substances 0.000 claims description 6
- 238000001755 magnetron sputter deposition Methods 0.000 claims description 6
- 239000000126 substance Substances 0.000 claims description 5
- 238000004140 cleaning Methods 0.000 claims description 4
- 238000000227 grinding Methods 0.000 claims description 4
- 239000004065 semiconductor Substances 0.000 claims description 4
- 238000005240 physical vapour deposition Methods 0.000 claims description 3
- 239000004094 surface-active agent Substances 0.000 claims description 3
- 239000010409 thin film Substances 0.000 claims description 3
- 230000008878 coupling Effects 0.000 abstract description 4
- 238000010168 coupling process Methods 0.000 abstract description 4
- 238000005859 coupling reaction Methods 0.000 abstract description 4
- 238000011161 development Methods 0.000 abstract description 3
- 230000005540 biological transmission Effects 0.000 abstract description 2
- 238000004891 communication Methods 0.000 abstract description 2
- 239000010410 layer Substances 0.000 description 75
- 235000012431 wafers Nutrition 0.000 description 27
- 150000002500 ions Chemical class 0.000 description 8
- 230000009471 action Effects 0.000 description 6
- 238000009826 distribution Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 5
- 230000008021 deposition Effects 0.000 description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 3
- 238000000137 annealing Methods 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 239000000376 reactant Substances 0.000 description 3
- 239000012495 reaction gas Substances 0.000 description 3
- 229910052710 silicon Inorganic materials 0.000 description 3
- 239000010703 silicon Substances 0.000 description 3
- 238000004544 sputter deposition Methods 0.000 description 3
- 229910004298 SiO 2 Inorganic materials 0.000 description 2
- 238000004630 atomic force microscopy Methods 0.000 description 2
- 238000010884 ion-beam technique Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000002105 nanoparticle Substances 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- PIGFYZPCRLYGLF-UHFFFAOYSA-N Aluminum nitride Chemical compound [Al]#N PIGFYZPCRLYGLF-UHFFFAOYSA-N 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000010894 electron beam technology Methods 0.000 description 1
- 238000000572 ellipsometry Methods 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 230000014509 gene expression Effects 0.000 description 1
- 239000011229 interlayer Substances 0.000 description 1
- 238000010295 mobile communication Methods 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000002161 passivation Methods 0.000 description 1
- 238000001259 photo etching Methods 0.000 description 1
- 229920002120 photoresistant polymer Polymers 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 230000000644 propagated effect Effects 0.000 description 1
- 150000003254 radicals Chemical class 0.000 description 1
- 230000006798 recombination Effects 0.000 description 1
- 238000005215 recombination Methods 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 230000008646 thermal stress Effects 0.000 description 1
- 230000000007 visual effect Effects 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
Classifications
-
- 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
- H03H9/02535—Details of surface acoustic wave devices
- H03H9/02543—Characteristics of substrate, e.g. cutting angles
- H03H9/02598—Characteristics of substrate, e.g. cutting angles of langatate substrates
-
- 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
- H03H3/08—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 resonators or networks using surface acoustic waves
-
- 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
- H03H9/02535—Details of surface acoustic wave devices
- H03H9/02614—Treatment of substrates, e.g. curved, spherical, cylindrical substrates ensuring closed round-about circuits for the acoustical waves
Landscapes
- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
Abstract
The application discloses a surface acoustic wave filter structure and a preparation method thereof, and relates to the technical field of surface acoustic wave filters. The surface acoustic wave filter structure provided by the application has the advantages of low transmission loss, high electromechanical coupling coefficient, high temperature stability and high power resistance, and can meet the development of 5G and 6G communication technologies.
Description
Technical Field
The application relates to the technical field of surface acoustic wave filters, in particular to a surface acoustic wave filter structure and a preparation method thereof.
Background
A surface acoustic wave is an elastic wave generated and propagated on the surface of a piezoelectric substrate material, whose amplitude decreases rapidly with increasing depth of the substrate material. The main action principle of the surface acoustic wave filter is to load voltage on a piezoelectric crystal (for example, an electrode of lithium tantalate), and form mechanical distortion in a crystal lattice of the piezoelectric crystal through a piezoelectric effect to realize acoustic-electric conversion.
The surface acoustic wave filter is mainly prepared by manufacturing two or more metal films on a polished surface of a substrate material having piezoelectric characteristics to form an electrode structure, namely an acoustic-electric transducer (interdigital transducer). The interdigital transducer is characterized in that a planar process of a semiconductor integrated circuit is adopted, a metal film with a certain thickness is plated on the surface of a piezoelectric substrate, and then a mask pattern of a designed IDT is deposited on the surface of the substrate by utilizing a photoetching method to respectively serve as an input transducer and an output transducer.
With the development of 5G and 6G communication technologies, the surface acoustic wave filter is required to have the characteristics of small input/output impedance error, low loss, large bandwidth, high temperature stability, high power resistance, good electromagnetic resistance, high reliability and the like, and the conventional surface acoustic wave filter cannot meet the requirements.
Disclosure of Invention
Therefore, the application provides a surface acoustic wave filter structure and a preparation method thereof, which are used for solving the problems of high loss, small bandwidth, high temperature stability difference and high power difference resistance of the surface acoustic wave filter in the prior art.
In order to achieve the above object, the present application provides the following technical solutions:
in a first aspect, a surface acoustic wave filter structure includes a substrate layer, a first high-resistance layer, a second high-resistance layer, a low-resistance layer, a piezoelectric layer, and an interdigital transducer sequentially disposed from bottom to top; the substrate layer is made of high-purity monocrystalline silicon, the first high-resistance layer is made of aluminum nitride, the second high-resistance layer is made of silicon carbide, the low-resistance layer is made of silicon dioxide, the piezoelectric layer is made of lithium tantalate, and the interdigital transducer is made of copper or aluminum-copper alloy; the thickness of the first high-resistance layer is 0.1-5 mu m, the thickness of the second high-resistance layer is 0.1-1 mu m, and the thickness of the low-resistance layer is 0.1-0.5 mu m.
Preferably, the substrate layer has a thickness of 100-250 μm.
Preferably, the first high-resistance layer is C-axis oriented aluminum nitride.
Preferably, the piezoelectric layer has a thickness of 5-10 μm.
Preferably, the interdigital transducer has a thickness of 0.08-1 μm.
In a second aspect, a method for manufacturing a surface acoustic wave filter structure, the method for manufacturing the surface acoustic wave filter structure includes:
step 1: depositing an aluminum nitride film on a high-purity monocrystalline silicon substrate by adopting a pure aluminum sputtering target and utilizing an intermediate frequency pulse magnetron sputtering technology;
step 2: bonding silicon carbide to the surface of the aluminum nitride film by adopting a surface activation bonding technology;
step 3: depositing a silicon dioxide film on the surface of silicon carbide by adopting a physical vapor deposition technology to form a composite layer of a high-purity monocrystalline silicon liner, aluminum nitride, silicon carbide and silicon dioxide from bottom to top;
step 4: bonding a lithium tantalate piezoelectric wafer on the composite layer by adopting a plasma activated surface technology;
step 5: grinding and thinning the surface of the lithium tantalate piezoelectric wafer by adopting a CMP (chemical mechanical polishing) technology;
step 6: flattening the surface of the lithium tantalate piezoelectric wafer by adopting a plasma flattening technology;
step 7: cleaning by adopting a surfactant to obtain a multilayer piezoelectric film material;
step 8: and forming an interdigital transducer on the surface of the lithium tantalate piezoelectric wafer by adopting a planar semiconductor process technology to obtain a final surface acoustic wave filter structure.
Preferably, in the step 1, the thickness of the aluminum nitride thin film deposited on the high purity single crystal silicon substrate is 0.4λ.
Preferably, in the step 1, the pure aluminum sputtering target is performed under the condition of 100-200ml/min flow rate by using an intermediate frequency pulse magnetron sputtering technology.
Compared with the prior art, the application has at least the following beneficial effects:
the application provides a surface acoustic wave filter structure and a preparation method thereof, wherein the surface acoustic wave filter structure has ultrahigh performance, and comprises a substrate layer, a first high-resistance layer, a second high-resistance layer, a low-resistance layer, a piezoelectric layer and an interdigital transducer, wherein the substrate layer, the first high-resistance layer, the second high-resistance layer, the low-resistance layer, the piezoelectric layer and the interdigital transducer are sequentially arranged from bottom to top, the substrate layer adopts high-purity monocrystalline silicon, the first high-resistance layer adopts aluminum nitride, the second high-resistance layer adopts silicon carbide, the low-resistance layer adopts silicon dioxide, the piezoelectric layer adopts lithium tantalate, and the interdigital transducer adopts copper or aluminum copper alloy. The surface acoustic wave filter structure provided by the application has the characteristics of low transmission loss, high electromechanical coupling coefficient, high temperature stability and high power resistance, and is suitable for high performance requirements of 5G and 6G mobile communication terminals.
Drawings
In order to more intuitively illustrate the prior art and the application, several exemplary drawings are presented below. It should be understood that the specific shape and configuration shown in the drawings are not generally considered limiting conditions in carrying out the application; for example, those skilled in the art will be able to make routine adjustments or further optimizations for the addition/subtraction/attribution division, specific shapes, positional relationships, connection modes, dimensional proportion relationships, and the like of certain units (components) based on the technical concepts and the exemplary drawings disclosed in the present application.
Fig. 1 is a schematic structural diagram of a surface acoustic wave filter structure according to a first embodiment of the present application;
FIG. 2 is a schematic diagram showing the relationship between the depth of energy distribution and the reflective layer according to the first embodiment of the present application;
FIG. 3 shows LiTaO in a SAW filter structure according to an embodiment of the present application 3 /SiO 2 Schematic of the structure of the SiC multilayer;
fig. 4 is a flowchart of a method for manufacturing a surface acoustic wave filter structure according to a second embodiment of the present application.
Reference numerals illustrate:
1. a substrate layer; 2. a first high-resistance layer; 3. a second high-resistance layer; 4. a low resistance layer; 5. a piezoelectric layer; 6. interdigital transducers.
Detailed Description
The application will be further described in detail by means of specific embodiments with reference to the accompanying drawings.
In the description of the present application: unless otherwise indicated, the meaning of "a plurality" is two or more. The terms "first," "second," "third," and the like in this disclosure are intended to distinguish between the referenced objects without a special meaning in terms of technical connotation (e.g., should not be construed as emphasis on the degree of importance or order, etc.). The expressions "comprising", "including", "having", etc. also mean "not limited to" (certain units, components, materials, steps, etc.).
The terms such as "upper", "lower", "left", "right", "middle", etc. are generally used herein for convenience of visual understanding with reference to the drawings and are not to be construed as absolute limitations on the positional relationship of the actual product. Such changes in the relative positional relationship without departing from the technical idea of the present application are also considered as the scope of the present application.
Example 1
Referring to fig. 1, the embodiment provides a surface acoustic wave filter structure, which comprises a substrate layer 1, a first high-resistance layer 2, a second high-resistance layer 3, a low-resistance layer 4, a piezoelectric layer 5 and an interdigital transducer 6, wherein the substrate layer 1, the first high-resistance layer 2, the second high-resistance layer 3, the low-resistance layer 4, the piezoelectric layer 5 and the interdigital transducer 6 are sequentially arranged from bottom to top, the substrate layer 1 adopts high-purity monocrystalline silicon (Si), the first high-resistance layer 2 adopts aluminum nitride (AlN), the second high-resistance layer 3 adopts silicon carbide (SiC), the low-resistance layer 4 adopts silicon dioxide (SiO) 2 ) The piezoelectric layer 5 is made of lithium tantalate (LiTaO 3 Abbreviated as LT), the interdigital transducer 6 employs copper (Cu) or an aluminum copper alloy.
Specifically, the substrate layer 1 is made of high-purity monocrystalline silicon with the thickness of 100-250 mu m, and the silicon has high heat conductivity coefficient, can rapidly release heat, and effectively improves the tolerance power of the device.
The first high-resistance layer 2 adopts C-axis oriented aluminum nitride with the thickness of 0.1-5 mu m. According to the established theoretical model, the relationship between the calculated energy distribution depth and the reflecting layer is shown in fig. 2 by utilizing a heterostructure simulation technology under the condition of multi-physical field coupling.
The energy distribution depth refers to when 99% of the energy is concentrated from the surface into a certain depth H, which is called the energy distribution depth. Conventional saw devices use only a single layer piezoelectric substrate, such as a lithium tantalate piezoelectric substrate, with an energy distribution depth of 8 wavelengths; with a multilayer film structure containing aluminum nitride thin films, energy can be concentrated in 2 wavelengths and 99% of the energy is concentrated in the lithium tantalate and silicon dioxide layers. The traditional structure has serious acoustic wave energy leakage, the embodiment adopts an aluminum nitride film structure, can concentrate the energy within 2 wavelength depths, has little energy loss in the depth direction, and improves the propagation loss of devices.
The second high-resistance layer 3 is made of silicon carbide, the thickness of the second high-resistance layer is 0.1-1 mu m, and the silicon carbide material can inhibit the transverse mode of sound waves and has good heat conduction characteristics, so that the propagation loss of the sound waves can be reduced, and the heat conduction capacity of the device is improved.
The low-resistance layer 4 is a silicon dioxide film with a thickness of 0.1-0.5 μm, and the silicon dioxide film is deposited between the second high-resistance layer 3 (silicon carbide high-resistance layer) and the lithium tantalate piezoelectric layer, and the silicon dioxide film has a low thermal expansion coefficient because the lithium tantalate piezoelectric layer has a high thermal expansion coefficient, so that the two layers can form temperature compensation, and high temperature stability of the device is realized. Referring to FIG. 3, FIG. 3 is a LiTaO-based 3 /SiO 2 Schematic diagram of a multi-layer structure of SiC.
The piezoelectric layer 5 is lithium tantalate, the thickness is between 5 and 10 mu m, the lithium tantalate material has a larger electromechanical coupling coefficient, a large-bandwidth surface acoustic wave filter can be easily realized, meanwhile, the Rayleigh wave modal spurious response can be effectively restrained, and the loss of the device is reduced.
The thickness of the interdigital transducer 6 (IDT) is required to be between 0.08 and 1 mu m according to the performance index of the device, and the interdigital transducer 6 adopts copper or aluminum copper alloy, preferably copper, because copper has good conductivity, the small resistance loss can be ensured, and meanwhile, the metal film thickness of the IDT can be reduced, thereby realizing the utilization process.
Example two
Referring to fig. 4, the present embodiment provides a method for manufacturing a surface acoustic wave filter structure according to the first embodiment.
Step 1: depositing an aluminum nitride film on a high-purity monocrystalline silicon substrate by adopting a pure aluminum sputtering target and utilizing an intermediate frequency pulse magnetron sputtering technology;
specifically, the thickness of aluminum nitride deposited on the silicon substrate in the embodiment is 0.4λ, and under the condition of 100-200ml/min flow, the pure aluminum sputtering target is adopted to prepare the aluminum nitride film on the silicon substrate by using the medium frequency pulse magnetron sputtering technology. The effect of flow ratio on microstructure, surface morphology, thickness and refractive index of aluminum nitride films was observed using x-ray diffraction (XRD), atomic Force Microscopy (AFM) and ellipsometry. Finding out the correlation of the microstructure, surface morphology, thickness and refractive index of the aluminum nitride film and the flow rate ratio, and changing the flow rate ratio changes the deposition rate of the aluminum nitride film when other deposition conditions are fixed; the present example will analyze the effect of the flow rate ratio in the reaction gas on the surface morphology, microstructure, thickness and refractive index of the aluminum nitride film in combination with the surface kinetic factors of the reaction deposition on the basis of the experimental results. And (3) finding out the optimal flow rate ratio of the reaction gas according to the comprehensive test result, avoiding passivation of the sputtering target caused by the reaction gas, obtaining higher deposition rate, and ensuring uniformity and consistency of film thickness of the aluminum nitride film.
Step 2: bonding silicon carbide to the surface of the aluminum nitride film by adopting a surface activation bonding technology;
specifically, the surface activation bonding is to bombard the surface of a wafer by using high-speed ions to remove surface oxide films and other pollutants, then apply a certain pressure to enable the two surfaces from which the oxide films are removed to be in close contact, reduce the surface energy by virtue of the action of chemical bonds, realize firm bonding on the atomic scale, achieve good bonding strength, eliminate the problem of thermal stress caused by unmatched thermal expansion coefficients without subsequent annealing. This is achieved by using O after washing with RCA solution 2 、N 2 、H 2 Or Ar plasma irradiates the surface of the wafer, and then the two wafers are pre-bonded together at room temperature, and the temperature is 200 ℃ to the upper partA sufficiently high bond strength is achieved after low temperature annealing at 400 ℃.
Step 3: depositing a silicon dioxide film on the surface of silicon carbide by adopting a physical vapor deposition technology to form a composite layer of a high-purity monocrystalline silicon liner, aluminum nitride, silicon carbide and silicon dioxide from bottom to top;
specifically, the on-chip temperature can be kept below 200 ℃ by controlling the process conditions, and meanwhile, the on-chip uniformity of the silicon dioxide film can be kept within 1% by controlling the equipment bias voltage value, sputtering power, sputtering temperature and other process parameters.
Step 4: bonding the lithium tantalate piezoelectric wafer on the composite layer by adopting a plasma activated surface technology;
specifically, the step is to bond the lithium tantalate piezoelectric wafer directly to the plasma activated surface, and high bonding strength can be realized under the vacuum low-temperature condition. The plasma for surface activation treatment is produced by low-pressure gas radio-frequency discharge and consists of electrons, ions, atoms decomposed by molecules, free radical particles and the like. Wafer surface activation is primarily accomplished by increasing the dangling bond energizing the wafer surface by mechanical impact and sputtering of ions against the wafer surface. Atoms and excitons generated during ionisation are different, e.g. Ar, O 2 、N 2 、NH 3 Etc., but they do not significantly affect the activation effect of the wafer surface. The activated wafer surface has strong adsorption capacity, the wafer bonding interface has higher bonding strength at lower temperature, and the atomic dangling bond of the bonding interface is easy to generate network recombination after annealing at proper temperature, so that a perfect covalent bond network is formed. The direct bonding and plasma activated bonding technique is suitable for the direct bonding of the piezoelectric film or silicon dioxide and the surface of the lithium tantalate piezoelectric material in this embodiment.
Step 5: grinding and thinning the surface of the lithium tantalate piezoelectric wafer by adopting a CMP (chemical mechanical polishing) technology;
specifically, under the action of a certain pressure and polishing solution, the surface of the lithium tantalate piezoelectric wafer relatively moves relative to the polishing pad, and planarization of the surface of the piezoelectric wafer material is realized by means of organic combination of the grinding action of the nano particles and the corrosion action of the oxidant. The rotating polished wafer is pressed on an elastic polishing pad rotating in the same direction, polishing liquid continuously flows between the wafer and the bottom plate, the upper disc and the lower disc rotate reversely at high speed, reactants on the surface of the polished wafer are continuously stripped, new polishing liquid is supplemented, and the reactants are taken away along with the polishing liquid. The newly exposed wafer surface bulges are subjected to chemical reaction with the polishing solution, and products of the chemical reaction are peeled off again, and the steps are repeated in a circulating way until the surface of the piezoelectric wafer is globally flat under the combined action of the substrate, the nano particles and the chemical reactant.
Step 6: flattening the surface of the lithium tantalate piezoelectric wafer by adopting a plasma flattening technology;
specifically, the ion flattening method is a method for micro-processing the surface of a wafer or a material by ions, can reach below 0.5nm in the aspect of controlling the film interlayer precision, is a process means for fine-adjusting the structure, and firstly, the thickness of the surface of the wafer is measured once by film thickness testing equipment to produce a MAP after the preparation of the lithium tantalate piezoelectric wafer is completed. Defining and distinguishing different positions through a pre-generated material thickness distribution MAP data graph by plasma flattening, rapidly processing each position through an ion beam, removing an atomic level of a film layer at the impact position through ion impact, and finally obtaining the required film layer thickness, wherein the uniformity of the film layer is improved due to the high-precision bombardment effect of a small-diameter ion beam in the process; in addition, because the related ion source is Ar+, the condition that the ion source and the film material generate chemical reaction to pollute the film does not exist in the flattening process, and the cleanliness of the surface of the film is greatly improved due to the cleaning effect of Ar+.
Step 7: cleaning by adopting a surfactant to obtain a multilayer piezoelectric film material;
step 8: and forming an interdigital transducer on the surface of the piezoelectric layer by adopting a planar semiconductor process technology to obtain the final surface acoustic wave filter structure.
Specifically, photoresist with a certain thickness is coated on the surface of the piezoelectric layer, then a transducer circuit image is formed after exposure and development, then copper or aluminum copper alloy material with a certain thickness is evaporated by electron beams, redundant copper or aluminum copper material is removed by adopting a stripping process, and finally an interdigital transducer is formed, so that a final surface acoustic wave filter structure is obtained.
Any combination of the technical features of the above embodiments may be performed (as long as there is no contradiction between the combination of the technical features), and for brevity of description, all of the possible combinations of the technical features of the above embodiments are not described; these examples, which are not explicitly written, should also be considered as being within the scope of the present description.
The application has been described above with particularity and detail in connection with general description and specific embodiments. It should be understood that numerous conventional modifications and further innovations may be made to these specific embodiments, based on the technical concepts of the present application; but these conventional modifications and further innovations may also fall within the scope of the claims of the present application as long as they do not depart from the technical spirit of the present application.
Claims (8)
1. The surface acoustic wave filter structure is characterized by comprising a substrate layer, a first high-resistance layer, a second high-resistance layer, a low-resistance layer, a piezoelectric layer and an interdigital transducer which are sequentially arranged from bottom to top; the substrate layer is made of high-purity monocrystalline silicon, the first high-resistance layer is made of aluminum nitride, the second high-resistance layer is made of silicon carbide, the low-resistance layer is made of silicon dioxide, the piezoelectric layer is made of lithium tantalate, and the interdigital transducer is made of copper or aluminum-copper alloy; the thickness of the first high-resistance layer is 0.1-5 mu m, the thickness of the second high-resistance layer is 0.1-1 mu m, and the thickness of the low-resistance layer is 0.1-0.5 mu m.
2. The surface acoustic wave filter structure of claim 1, wherein the substrate layer has a thickness of 100-250 μm.
3. The saw filter structure of claim 1, wherein said first high resistance layer is C-axis oriented aluminum nitride.
4. The surface acoustic wave filter structure as set forth in claim 1, wherein the piezoelectric layer has a thickness of 5-10 μm.
5. The surface acoustic wave filter structure of claim 1, wherein the interdigital transducer has a thickness of 0.08-1 μm.
6. A method for producing a surface acoustic wave filter structure, characterized in that the method for producing a surface acoustic wave filter structure as claimed in any one of claims 1 to 5 comprises:
step 1: depositing an aluminum nitride film on a high-purity monocrystalline silicon substrate by adopting a pure aluminum sputtering target and utilizing an intermediate frequency pulse magnetron sputtering technology;
step 2: bonding silicon carbide to the surface of the aluminum nitride film by adopting a surface activation bonding technology;
step 3: depositing a silicon dioxide film on the surface of silicon carbide by adopting a physical vapor deposition technology to form a composite layer of a high-purity monocrystalline silicon liner, aluminum nitride, silicon carbide and silicon dioxide from bottom to top;
step 4: bonding a lithium tantalate piezoelectric wafer on the composite layer by adopting a plasma activated surface technology;
step 5: grinding and thinning the surface of the lithium tantalate piezoelectric wafer by adopting a CMP (chemical mechanical polishing) technology;
step 6: flattening the surface of the lithium tantalate piezoelectric wafer by adopting a plasma flattening technology;
step 7: cleaning by adopting a surfactant to obtain a multilayer piezoelectric film material;
step 8: and forming an interdigital transducer on the surface of the lithium tantalate piezoelectric wafer by adopting a planar semiconductor process technology to obtain a final surface acoustic wave filter structure.
7. The method of manufacturing a surface acoustic wave filter structure according to claim 6, wherein in the step 1, the thickness of the aluminum nitride thin film deposited on the high purity single crystal silicon substrate is 0.4λ.
8. The method of manufacturing a surface acoustic wave filter structure according to claim 6, wherein in the step 1, the pure aluminum sputtering target is performed under a flow rate of 100-200ml/min by using an intermediate frequency pulse magnetron sputtering technique.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310864870.2A CN116865704A (en) | 2023-07-13 | 2023-07-13 | Surface acoustic wave filter structure and preparation method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310864870.2A CN116865704A (en) | 2023-07-13 | 2023-07-13 | Surface acoustic wave filter structure and preparation method thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN116865704A true CN116865704A (en) | 2023-10-10 |
Family
ID=88233821
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310864870.2A Pending CN116865704A (en) | 2023-07-13 | 2023-07-13 | Surface acoustic wave filter structure and preparation method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN116865704A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117066978A (en) * | 2023-10-16 | 2023-11-17 | 天通控股股份有限公司 | Thinning method of lithium tantalate bonding wafer |
-
2023
- 2023-07-13 CN CN202310864870.2A patent/CN116865704A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117066978A (en) * | 2023-10-16 | 2023-11-17 | 天通控股股份有限公司 | Thinning method of lithium tantalate bonding wafer |
| CN117066978B (en) * | 2023-10-16 | 2024-01-05 | 天通控股股份有限公司 | Thinning method of lithium tantalate bonding wafer |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP6427712B2 (en) | Bonding method | |
| TWI672839B (en) | Joining method | |
| TWI780103B (en) | Elastic wave element and method of manufacturing the same | |
| CN203851109U (en) | Composite substrate | |
| CN108493325A (en) | A kind of high-frequency high-performance SAW device and preparation method thereof | |
| CN111446944A (en) | Air gap type film bulk acoustic resonator beneficial to integration and preparation method thereof | |
| CN116865704A (en) | Surface acoustic wave filter structure and preparation method thereof | |
| JP6644208B1 (en) | Joint and elastic wave element | |
| JP2018207355A (en) | Bonded body of piezoelectric material substrate, bonding method, and elastic wave element | |
| CN113726302A (en) | Manufacturing method of interdigital transducer of surface acoustic wave filter | |
| JP2019193242A (en) | Composite substrate for surface acoustic wave device and manufacturing method thereof | |
| CN117013984B (en) | Bonding wafer and film surface acoustic wave device | |
| CN112271249B (en) | Silicon-based/ferroelectric single crystal material low-temperature wafer bonding and thin film processing method | |
| CN212381185U (en) | Air gap type film bulk acoustic resonator beneficial to integration | |
| CN220342293U (en) | Surface acoustic wave filter structure | |
| CN117118388A (en) | Multilayer composite wafer and thin film elastic wave device | |
| WO2019188350A1 (en) | Joint and elastic wave element | |
| CN112688658B (en) | Piezoelectric substrate, preparation method and electronic component | |
| CN108494380A (en) | SAW filter materials and preparation method thereof | |
| JP7262421B2 (en) | Piezoelectric composite substrate and manufacturing method thereof | |
| JP2002290182A (en) | Manufacturing method of surface acoustic wave element baseboard | |
| CN112968124A (en) | Surface acoustic wave filter with non-continuous substrate structure and preparation method thereof | |
| JP2019161634A (en) | Composite substrate for surface acoustic wave element and manufacturing thereof | |
| JPWO2018203430A1 (en) | Elastic wave device and method of manufacturing the same | |
| JPH0316409A (en) | Surface acoustic wave device and manufacture thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |