CN115694391A

CN115694391A - Method for manufacturing composite substrate, and surface acoustic wave filter

Info

Publication number: CN115694391A
Application number: CN202211436373.4A
Authority: CN
Inventors: 王阳; 吴洋洋; 曹庭松; 陆彬
Original assignee: Beijing Super Material Information Technology Co ltd
Current assignee: Beijing Super Material Information Technology Co ltd
Priority date: 2022-11-16
Filing date: 2022-11-16
Publication date: 2023-02-03

Abstract

The application provides a manufacturing method of a composite substrate for a surface acoustic wave filter, the composite substrate and the surface acoustic wave filter, wherein the manufacturing method comprises the following steps: and an isolation layer is deposited on the surface of the support substrate, and the sound velocity of the isolation layer responding to the surface acoustic wave is lower than that of the support substrate responding to the surface acoustic wave. And performing ion implantation on the surface of the piezoelectric film substrate to form a defect layer. The surface of the spacer layer and the surface of the defective layer are activated and then mechanically bonded to form a substrate assembly. And heating the substrate joint body in a vacuum environment at a stripping temperature so that the substrate joint body is separated along the ion concentration peak of the defect layer to form a composite substrate with a partial defect layer. And carrying out planarization treatment and annealing treatment on the defect layer of the composite substrate. The method can effectively reduce the stress mismatching between the support substrate and the piezoelectric film and reduce the leakage of the surface acoustic wave energy to the support substrate.

Description

Method for manufacturing composite substrate, and surface acoustic wave filter

Technical Field

The application relates to the technical field of semiconductors, in particular to a manufacturing method of a composite substrate of a surface acoustic wave filter, the composite substrate and the surface acoustic wave filter.

Background

Radio frequency front end parts of mobile communication systems are advancing from 3G, 4G to 5G, and the frequency bands used are advancing to higher frequencies (3 GHz or higher). A surface acoustic wave filter (SAW) includes a composite substrate in which a piezoelectric thin film is provided on a supporting substrate, as one of components of a radio frequency front end portion.

The supporting substrate and the piezoelectric film are made of different materials, the linear expansion coefficients of the supporting substrate and the piezoelectric film have large difference, and large stress is easily generated on the surfaces of the supporting substrate and the piezoelectric film in the processing process of the composite substrate, so that the piezoelectric film is broken. Further, the surface acoustic wave of the piezoelectric thin film has a problem that energy loss due to leakage to the supporting substrate is excessively large and Q value is deteriorated when propagating.

Disclosure of Invention

It is a primary object of the present application to overcome at least one of the above-mentioned drawbacks of the prior art and to provide a method for manufacturing a composite substrate, which can effectively reduce the stress mismatch between the supporting substrate and the piezoelectric film and reduce the leakage of surface acoustic wave energy to the supporting substrate.

In order to achieve the purpose, the following technical scheme is adopted in the application:

according to an aspect of the present application, there is provided a manufacturing method of a composite substrate for a surface acoustic wave filter, the manufacturing method including the steps of:

s1, depositing an isolation layer, providing a support substrate, wherein the support substrate is provided with a first surface and a second surface which are oppositely arranged, depositing the isolation layer on the first surface, and the sound velocity of the isolation layer responding to the surface acoustic wave is lower than that of the support substrate responding to the surface acoustic wave;

s2, providing a piezoelectric film substrate, and performing ion implantation on the surface of the piezoelectric film substrate to form a defect layer;

s3, cleaning and activating, removing impurities attached to the surfaces of the isolation layer and the defect layer, and performing activation treatment on the surfaces of the isolation layer and the defect layer;

s4, mechanically bonding, namely mechanically bonding the surface of the isolation layer and the surface of the defect layer to form a substrate conjugant;

s5, stripping, namely heating the substrate joint body at a stripping temperature in a vacuum environment to separate the substrate joint body along the ion concentration peak of the defect layer to form a composite substrate with a partial defect layer;

s6, repairing the piezoelectric property, flattening the defect layer of the composite substrate, and annealing at the temperature of 0-100 ℃ lower than the stripping temperature.

According to an embodiment of the present application, the isolation layer is a single layer structure, and the isolation layer is a single crystal silicon nitride film.

According to an embodiment of the application, in step S1, the isolation layer is deposited on the first surface of the support substrate by an epitaxial growth deposition method, the epitaxial growth deposition method including: heating the reaction chamber and the supporting substrate, introducing nitrogen gas with a first gas flow into the reaction chamber, adsorbing the nitrogen gas on the first surface of the supporting substrate, reacting to generate a grown crystal SiN, moving the grown crystal SiN on a crystal face in sequence, entering the crystal lattice, and growing on the first surface in a diffusion mode.

According to an embodiment of the present application, step S6 includes:

s6-1, randomly positioning a plurality of characteristic positions of the defect layer of the composite substrate, collecting Raman spectrum values of the characteristic positions, and averaging to obtain a first Raman spectrum value of the defect layer;

s6-2, calculating a second Raman spectrum value according to the Euler angle crystal orientation of the composite substrate;

s6-3, flattening the defect layer by adopting a mechanical chemical polishing method, monitoring the Raman spectrum values of the characteristic positions, and stopping the chemical mechanical polishing when the difference between the average Raman spectrum value of the characteristic positions and the second Raman spectrum value is less than 10% of the second Raman spectrum value;

s6-4, annealing the composite substrate at a temperature lower than the stripping temperature by 0-100 ℃.

According to one embodiment of the application, the isolation layer is of a single-layer structure and is an SiOxNy film, wherein x/y is more than or equal to 1 and less than or equal to 2.

According to an embodiment of the application, in step S1, the isolation layer is deposited on the first surface of the support substrate by a pulsed magnetron sputtering deposition method, the pulsed magnetron sputtering deposition method including: and placing the support substrate and the silicon target material in a vacuum chamber, and introducing oxygen and nitrogen into the vacuum chamber, wherein the gas flow ratio of the oxygen to the nitrogen is 1-1.

According to an embodiment of the present application, the spacer layer has a thickness of (0.5-1) λ, where λ refers to a wavelength at which the saw filter responds to surface acoustic waves.

According to an embodiment of the present application, the isolation layer is a single layer structure, and the isolation layer is SiN _a The film is characterized in that a is less than or equal to 1.1.

According to an embodiment of the present application, in step S1, the isolation layer is deposited on the first surface of the support substrate by a plasma enhanced chemical vapor deposition method, the plasma enhanced chemical vapor deposition method including: placing the support substrate in a vacuum chamber, introducing nitrogen and silane into the vacuum chamber, wherein the gas flow ratio of the nitrogen to the silane is 1-1.

According to an embodiment of the present application, the isolation layer is a single layer structure, and the isolation layer is SiN _a F _b The film, wherein b/a is more than or equal to 0.01 and less than or equal to 0.1.

According to an embodiment of the application, the isolation layer is bilayer structure, including first isolation layer and second isolation layer, the second isolation layer sets up the supporting substrate with between the first isolation layer, the sound velocity of first isolation layer response surface acoustic wave is less than the sound velocity of second isolation layer response surface acoustic wave.

According to an embodiment of the present application, the isolation layer in step S1 includes a first isolation layer and a sacrificial layer, and depositing the isolation layer is: and depositing the first isolation layer on the first surface, and depositing the sacrificial layer on the second surface, wherein the sacrificial layer and the first isolation layer are the same in material, thickness and deposition process parameters.

According to an embodiment of the present application, step S6 is followed by step S7, wherein the sacrificial layer is removed by a chemical mechanical polishing process.

According to another aspect of the present application, there is provided a composite substrate for a surface acoustic wave filter, the composite substrate being made by the above-described method, the composite substrate including a piezoelectric film, an isolation layer, and a support base plate,

the isolation layer is disposed between the piezoelectric film and the support substrate,

the isolation layer is single crystal silicon nitride; siOxNy film, x/y is more than or equal to 1 and less than or equal to 2; a is less than or equal to 1.1; siNaFb film, 0.01-0.1.

According to another aspect of the present application, there is provided a composite substrate for a surface acoustic wave filter, characterized in that: the composite substrate is manufactured by the method, the composite substrate comprises a piezoelectric film, a first isolation layer, a second isolation layer and a support substrate,

the piezoelectric film, the first isolation layer and the second isolation layer are sequentially stacked on the support substrate, and the sound velocity of the first isolation layer responding to the surface acoustic wave is lower than that of the second isolation layer responding to the surface acoustic wave.

According to the on-the-other aspect of this application, a surface acoustic wave filter is provided, including interdigital transducer and composite substrate, composite substrate adopts foretell composite substrate, interdigital transducer sets up composite substrate piezoelectric film keeps away from the surface of supporting substrate.

According to an embodiment of the present application, the interdigital transducer includes:

a buffer layer disposed on the piezoelectric thin film of the composite substrate, the buffer layer including metallic titanium, the buffer layer having a thickness of 0.5% λ 'or less, where λ' represents a wavelength of an elastic wave determined by an electrode period of the interdigital transducer;

the metal layer is arranged on the surface, far away from the piezoelectric film, of the buffer layer and comprises aluminum, wherein the content of the aluminum is more than 95wt%, the metal layer further comprises one or more materials selected from Cu, W, mo, cr, ag, pt, ga, nb, ta, au and Si, and the thickness of the metal layer is between 1% lambda and 30% lambda'.

According to an embodiment of the application, the average film thickness H of the interdigital transducer and the wavelength λ 'of the elastic wave determined by the electrode period of the interdigital transducer satisfy 9% ≦ H/λ' ≦ 15%.

According to the technical scheme, the manufacturing method of the composite substrate has the advantages and positive effects that:

the application provides a manufacturing method of a composite substrate for a surface acoustic wave filter, which comprises the following steps: and depositing an isolation layer, providing a support substrate, wherein the support substrate is provided with a first surface and a second surface which are oppositely arranged, the isolation layer is deposited on the first surface, and the sound velocity of the isolation layer responding to the surface acoustic wave is lower than that of the support substrate responding to the surface acoustic wave. The isolation layer is arranged through a deposition process, and the sound velocity of the isolation layer responding to the surface acoustic wave is lower than that of the support substrate responding to the surface acoustic wave, so that the leakage of the surface acoustic wave energy to the support substrate can be effectively reduced.

Performing ion implantation on the surface of the piezoelectric film substrate to form a defect layer; removing impurities attached to the surface of the isolation layer and the surface of the defect layer, and performing activation treatment on the surface of the isolation layer and the surface of the defect layer; and performing mechanical bonding treatment on the surface of the isolation layer and the surface of the defect layer to form a substrate joint body. The isolation layer has good flatness, provides a good joint surface for the mechanical bonding treatment of the piezoelectric film substrate, reduces the problem of breakage due to mismatching of stress between the piezoelectric film and the supporting substrate, and improves the quality of the composite substrate.

And heating the substrate assembly at a stripping temperature in a vacuum environment to separate the substrate assembly along the ion concentration peak of the defect layer, thereby forming a composite substrate with a partial defect layer. The isolation layer is arranged on the supporting substrate, so that the leakage of the longitudinal component of the surface acoustic wave to the single crystal supporting substrate can be effectively blocked, and the problem of stress mismatch between the supporting substrate and the piezoelectric single crystal film is solved. At the defect layer, the crystallinity and piezoelectric characteristics of the piezoelectric single crystal of the piezoelectric thin film substrate are degraded by ion implantation, and therefore, it is necessary to perform piezoelectric characteristic repair on the crystallinity and piezoelectric characteristics of the composite substrate, to perform planarization treatment on the defect layer of the composite substrate, and to perform annealing treatment at a temperature between 0 and 100 ℃ lower than the peeling temperature.

Drawings

The above and other features and advantages of the present application will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings.

Fig. 1 is a flowchart of a method of manufacturing a composite substrate of the present application.

Fig. 2 is a schematic view of a composite substrate manufactured by the manufacturing method of the present application.

Fig. 3 is a schematic view of a composite substrate (separation layer divided into two layers) manufactured by the manufacturing method of the present application.

Fig. 4 is a schematic diagram of an interdigital transducer of the present application.

Fig. 5 is a schematic diagram of an interdigital transducer of the present application in combination with a composite substrate.

Wherein the reference numerals are as follows:

10-a composite substrate;

101-a support substrate;

102-an isolation layer;

1021-a first spacer layer;

1022 — a second isolation layer;

103-a piezoelectric film;

11-electronics (interdigital transducers);

111-a buffer layer;

112-a metal layer;

w-electrode width of the electronic device;

g-electrode spacing of electronic devices;

h-average film thickness of electrodes of electronic devices.

Detailed Description

Exemplary embodiments that embody features and advantages of the present application are described in detail below in the specification. As will be realized, the application is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the invention, and the description and drawings are to be regarded as illustrative in nature, and not as restrictive.

In the following description of various exemplary embodiments of the present application, reference is made to the accompanying drawings, which form a part hereof, and in which are shown by way of illustration various exemplary structures, systems, and steps in which aspects of the application may be practiced. It is to be understood that other specific arrangements of parts, structures, example devices, systems, and steps may be utilized, and structural and functional modifications may be made without departing from the scope of the present application. Moreover, although the terms "upper", "intermediate", "inner", and the like may be used in this specification to describe various example features and elements of the application, these terms are used herein for convenience only, e.g., in accordance with the orientation of the examples described in the figures. Nothing in this specification should be construed as requiring a specific three dimensional orientation of structures in order to fall within the scope of this application.

In order to make the aforementioned objects, features and advantages of the present application comprehensible, embodiments accompanying figures are described in detail below.

As shown in fig. 1 to 2, a method of manufacturing a composite substrate 10 for a surface acoustic wave filter of the present application includes the steps of:

s1, depositing an isolation layer: providing a supporting substrate 101, wherein the supporting substrate 101 is provided with a first surface and a second surface which are oppositely arranged, an isolating layer 102 is deposited on the first surface, and the acoustic velocity of the isolating layer 102 responding to the surface acoustic wave is lower than that of the supporting substrate 101 responding to the surface acoustic wave;

s2, providing a piezoelectric film substrate: performing ion implantation on the surface of the piezoelectric film substrate to form a defect layer;

s3, cleaning and activating: removing impurities attached to the surface of the isolation layer 101 and the surface of the defect layer, and performing activation treatment on the surface of the isolation layer and the surface of the defect layer;

s4, mechanical bonding: carrying out mechanical bonding treatment on the surface of the isolation layer 101 and the surface of the defect layer to form a substrate conjugant;

s5, stripping: heating the substrate assembly at a stripping temperature in a vacuum environment to separate the substrate assembly along the ion concentration peak of the defect layer to form a composite substrate with a partial defect layer;

s6, piezoelectric property restoration: and flattening the defect layer of the composite substrate, and annealing at a temperature of 0-100 ℃ lower than the stripping temperature.

The defect layer of the composite substrate after the planarization process forms a piezoelectric film 103, the isolation layer 102 and the support substrate 101 constitute a composite substrate 10, and an electronic device 11 may be disposed on the composite substrate 10. The isolation layer is arranged between the supporting substrate and the piezoelectric film, so that the leakage of longitudinal components of the surface acoustic waves to the single crystal supporting substrate can be effectively blocked, and the problem of stress mismatch between the supporting substrate and the piezoelectric single crystal film is simultaneously relieved.

The supporting substrate 101 may be one selected from SiC, siN, si, glass, quartz, alN, sapphire, and ceramic. In the above materials, the difference in linear expansion coefficient between the support substrate and the piezoelectric thin film substrate is preferably 10% or less. More preferably, the support substrate may be a single crystalline silicon substrate. The stripping temperature is 100-250 ℃.

In the ion implantation step, ions are implanted from a flat surface of the piezoelectric thin film substrate, and a defect layer is formed between the surface and an ion concentration peak near the surface. The piezoelectric thin film substrate may be one of LiTaO3, liNbO3, li2B4O7, and La3Ga5SiO 14. When the ion implantation method is adopted to implant H +, the implantation dosage parameters are as follows: the implantation dose is 5 × 10 ¹⁶ ions/cm ² The implantation energy is 400keV. Thus, the H + concentration reaches a peak at a distance of about 0.7 μm from the injection side of the piezoelectric thin film substrate, and a defect layer is formed in this region. The implanted ions are selected according to the material of the piezoelectric film substrate, and can be hydrogenIons, helium ions, oxygen ions, and the like, and the ion implantation conditions are selected according to the material of the piezoelectric thin film substrate and the thickness of the piezoelectric thin film.

At the defect layer, the crystallinity and piezoelectric characteristics of the piezoelectric single crystal are reduced by ion implantation, and therefore, it is necessary to repair the crystallinity and piezoelectricity of a part of the defect layer of the composite substrate formed after the peeling so that the average surface roughness Ra of the piezoelectric thin film formed of the part of the defect layer after the planarization treatment is less than 2nm.

In this embodiment, the isolation layer 102 is a single-layer structure, and the isolation layer 102 is a single-crystal silicon nitride film and adopts the single-crystal silicon nitride film as the isolation layer, so that the stress mismatch between the support substrate and the piezoelectric film can be effectively reduced, and the leakage of the surface acoustic wave energy to the support substrate can be reduced.

In this embodiment, in step S1, the isolation layer 102 is deposited on the first surface of the support substrate 101 by an epitaxial growth deposition method, which includes: the reaction chamber and the supporting substrate 101 are heated, nitrogen gas with a first gas flow rate is introduced into the reaction chamber, the nitrogen gas is adsorbed on the first surface of the supporting substrate 101 and reacts to generate a growing crystal SiN, and the growing crystal SiN sequentially moves on a crystal face to enter a crystal lattice and grows on the first surface in a diffusion mode. The isolation layer deposited by adopting the growth deposition method has good flatness, provides a good joint surface for the mechanical bonding treatment of the defect layer of the piezoelectric film substrate, reduces the problem of breakage caused by unmatched stress between the piezoelectric single crystal film and the supporting substrate, and improves the quality of the composite substrate.

It should be noted that the square of the flow rate of the first flow rate of nitrogen gas is proportional to the SiN growth rate, but the growth rate does not increase after reaching the stability limit. The first gas flow rate may be in the range of 100slm to 150slm, where slm is standard liters per minute.

In the present embodiment, step S6 includes:

s6-1, randomly positioning a plurality of characteristic positions of a defect layer of the composite substrate, collecting Raman spectrum values of the characteristic positions, and calculating the average value to be used as a first Raman spectrum value of the defect layer;

s6-3, flattening the defect layer by adopting a mechanical chemical grinding method, monitoring the Raman spectrum values of the plurality of characteristic positions, and stopping the chemical mechanical grinding when the difference between the average Raman spectrum value of the plurality of characteristic positions and the second Raman spectrum value is less than 10% of the second Raman spectrum value;

s6-4, annealing the composite substrate at the temperature of 0-100 ℃ lower than the stripping temperature.

Whether the defect layer is flattened or not is determined through the Raman spectrum value, the defect layer after flattening can meet the performance requirement, the condition that flattening treatment is insufficient or excessive can not occur, leakage of longitudinal components of the acoustic surface waves to the single crystal supporting substrate is guaranteed to be blocked, and meanwhile mismatching of stress between the supporting substrate and the piezoelectric single crystal film is relieved.

In other embodiments, the isolation layer 102 is a single layer structure, and the isolation layer 102 is a SiOxNy film, wherein x/y is greater than or equal to 1 and less than or equal to 2. The existing surface acoustic wave filter can show a Q value of over 1000 and an electromechanical coupling coefficient of about 7% -10% at a frequency below 3GHz, and the electromechanical coupling coefficient is required to be over 10% by the new 5G standard. The electromechanical coupling coefficient of more than 10% cannot be satisfied with a single SiN isolation layer. The isolation layer adopts an SiOxNy layer, wherein x/y is more than or equal to 1 and less than or equal to 2, the electromechanical coupling coefficient of the substrate can be improved, and meanwhile, the SiOxNy layer has hydrophobicity, so that the pollution of air or moisture in equipment to the surface of the isolation layer can be effectively avoided, and the stability of the device is reduced.

In this embodiment, the isolation layer 101 is deposited on the first surface of the supporting substrate 101 by a pulsed magnetron sputtering deposition method, which includes: placing a supporting substrate 101 and a silicon target material in a vacuum chamber, and introducing oxygen and nitrogen into the vacuum chamber, wherein the gas flow ratio of the oxygen to the nitrogen is 1-1 ² . And performing pulse magnetron sputtering to form the SiOxNy film. Through inspectionIn this example, the preferred orientation of the isolation layer is (100) plane, the residual stress is-1.2 + -0.35 GPa, and the deposition rate is 2.5nm/min. The method adopts a pulse magnetron sputtering deposition method, can realize higher coupling coefficient of the isolation layer, selects the gas flow ratio of oxygen to nitrogen as 1-1 ² The acoustic velocity of the prepared isolation layer responding to the acoustic surface wave is lower than that of the support substrate responding to the acoustic surface wave, so that leakage of the acoustic surface wave to the support substrate is effectively reduced.

In the present embodiment, the spacer layer 101 has a thickness of (0.5-1) λ, where λ refers to the wavelength of the surface acoustic wave filter in response to surface acoustic waves. In order to ensure the function of the spacer and further reduce the leakage of the surface acoustic wave to the supporting substrate, it is necessary to ensure that the thickness of the spacer 101 is (0.5-1) λ, where λ refers to the wavelength of the surface acoustic wave filter in response to the surface acoustic wave.

In other embodiments, the isolation layer 102 is a single layer structure, and the isolation layer 102 is a SiNa film, where a is less than or equal to 1.1. The isolation layer 102 is deposited on the first surface of the support substrate 101 by a plasma enhanced chemical vapor deposition method including: the supporting substrate 101 is placed in a vacuum chamber, nitrogen and silane are introduced into the vacuum chamber, wherein the gas flow ratio of the nitrogen to the silane is 1-1.

The plasma is utilized to excite the chemical reaction, so that the defect that high temperature and high pressure are needed to activate raw materials in the conventional chemical reaction can be avoided. Furthermore, the supporting substrate can perform revolution motion by taking the central point of the vacuum chamber as a reference point or a preset axis, and perform rotation motion around the central axis of the supporting substrate, so that the supporting substrate can uniformly receive the action of plasma, and the influence of uneven concentration distribution of the reaction gas on the quality of the isolation layer is reduced. Further, the input power density of the plasma ranges from 0.1W/L to 10W/L.

Further preferably, the isolation layer is a fluorine-doped SiNaFb layer, wherein b/a is more than or equal to 0.01 and less than or equal to 0.1, the isolation layer is still deposited by adopting a plasma enhanced chemical vapor deposition method, nitrogen and fluorine-containing compound gas are introduced into the vacuum chamber, and the gas flow ratio of the fluorine-containing compound gas to the nitrogen is 1. The fluorine-containing compound gas can be one or more of tetrafluoroethylene, hexafluoropropylene oxide, perfluorooctyl triethoxysilane, trimethyl fluorosilane and octafluorobutene.

As shown in fig. 3, in the composite substrate manufactured by the method for manufacturing a composite substrate of the present application, the isolation layer 102 has a double-layer structure including a first isolation layer 1021 and a second isolation layer 1022, the second isolation layer 1022 is disposed between the supporting substrate 101 and the first isolation layer 1021, and the acoustic velocity of the first isolation layer 1021 in response to a surface acoustic wave is lower than the acoustic velocity of the second isolation layer 1022 in response to a surface acoustic wave. The insertion loss of the surface acoustic wave filter can be reduced, the temperature characteristic of the filter is improved, namely, the drift of the resonant frequency of the filter caused by the influence of the external environment temperature is reduced, and the response bandwidth of the surface acoustic wave filter is enlarged.

The first isolation layer 1021 is thicker than the second isolation layer 1022, the first isolation layer is a polycrystalline SiO2 film, and the second isolation layer is a single crystal Si3N4 film. A bonding layer can be arranged between the first isolation layer and the second isolation layer, the bonding layer can be made of metal oxide, metal nitride, ti and the like, and the height of the bonding layer can be set to be 0.4nm-1.2nm. The absolute value of the frequency temperature coefficient TCF can be reduced, the electromechanical coupling coefficient is increased, and the relative bandwidth is enlarged. That is, the improvement of the temperature characteristic and the enlargement of the relative bandwidth can be achieved at the same time.

The single crystal Si3N4 film of the second isolation layer is deposited on the surface of the support substrate in an Atomic Layer Deposition (ALD) mode; and introducing reaction gas with a first flow into the reaction chamber, wherein the reaction gas has a first flow rate and a second flow rate, the first flow rate is less than the second flow rate, the second flow rate is adopted in the outer edge area of the surface of the support substrate, the first flow rate is adopted in the middle area of the surface of the support substrate, and the deposition rate of the outer edge of the substrate is less than that of the middle area of the substrate. The deposition method of the single crystal Si3N4 film can also adopt the modes of single crystal epitaxial growth, molecular beam epitaxy, ion beam evaporation, radio frequency magnetron sputtering and the like. After deposition is finished, the contact surface of the second isolation layer and the support substrate is a smooth and flat surface.

The first isolating layer polycrystalline SiO2 film is deposited on the surface of the supporting substrate in a chemical vapor deposition mode.

In some other embodiments, the isolation layer 102 includes a first isolation layer 1021 and a sacrificial layer, and the deposition of the isolation layer 102 is: the first isolation layer 1021 is deposited on the first surface, and the sacrificial layer is deposited on the second surface, wherein the material, the thickness and the deposition process parameters of the sacrificial layer and the first isolation layer 1021 are the same. The first isolation layer and the sacrificial layer have opposite directions of stress on the supporting substrate and can offset the stress, so that the flatness of the supporting substrate in subsequent processing steps can be ensured, and the bending of the supporting substrate is reduced. In this embodiment, the sacrificial layer is removed by a chemical mechanical polishing process.

As shown in fig. 1 to 3, the present application also provides a composite substrate 10 for a surface acoustic wave filter, the composite substrate being made by the above-described method, the composite substrate 10 including a piezoelectric film 103, a first spacer 1021, a second spacer 1022 and a supporting substrate 101,

the piezoelectric film 103, the first spacer 1021, and the second spacer 1022 are sequentially stacked on the supporting substrate 101, and 1 the acoustic velocity of the first spacer 1021 in response to a surface acoustic wave is lower than the acoustic velocity of the second spacer 1022 in response to a surface acoustic wave.

As shown in fig. 4, the present application also provides a surface acoustic wave filter, which includes an interdigital transducer 11 and a composite substrate 10, where the composite substrate 10 is the composite substrate described above, and the interdigital transducer 11 is disposed on the surface of the piezoelectric film 103 of the composite substrate 10, which is far from the support substrate 101.

In the present embodiment, as shown in fig. 5, the interdigital transducer 11 includes a buffer layer 111 and a metal layer 112. The buffer layer 111 is provided on the piezoelectric film 103 of the composite substrate 10, the buffer layer 111 including metallic titanium, and the thickness of the buffer layer is 0.5% λ 'or less, where λ' represents a wavelength of an elastic wave determined by an electrode period of the interdigital transducer. The metal layer 112 is disposed on a surface of the buffer layer 111 far from the piezoelectric film 103, the metal layer 112 includes aluminum, wherein the content of aluminum is more than 95wt%, the metal layer 112 further includes one or more materials selected from Cu, W, mo, cr, ag, pt, ga, nb, ta, au, and Si, and the thickness of the metal layer 112 is between 1% λ 'and 30% λ'.

It should be noted that, the metal titanium is used as the buffer layer, which is beneficial to forming a strong Al texture on the metal layer Al thin film arranged on the buffer layer, enhancing the power tolerance of the Al thin film, and reducing the resistivity of the Al thin film. Furthermore, the thickness of the buffer layer is designed, and the metal titanium layer with the thickness of 0.5% lambda' is adopted, so that the density and the smoothness of the metal Al film can be improved, the excitation of the surface acoustic wave is enhanced, the insertion loss of a surface acoustic wave device is reduced, and the maximum withstand power of the SAW is improved. For example, when the wavelength λ' of the elastic wave determined by the electrode period of the interdigital transducer is 2 μm, the thickness of the buffer layer is 10nm or less, and in a preferred embodiment, the thickness of the buffer layer may be set to 2nm, which can further provide a strong texture to the Al thin film to be formed thereon. The thickness of the titanium buffer layer has direct influence on the strength of an Al texture, after the titanium buffer layer is formed, an Al film on the titanium buffer layer grows mainly in a layered mode, the Al is in a surface structure, the Al surface is a low-energy surface and has a preferential growth tendency, the Al film growing on the titanium buffer layer shows a strong texture, but when the titanium buffer layer reaches a certain degree to form a continuous film, the deposition of the Al film on the titanium buffer layer starts to be mainly in an island-shaped growth mode, and a polycrystalline structure without preferred orientation is formed. Therefore, the thickness range of the titanium buffer layer formed by the Al texture is narrow, the thickness of the titanium buffer layer is less than 10nm, preferably less than 2nm, the strong Al texture can be obtained, the obtained Al thin film has a uniform and compact structure, the critical load is increased, and the adhesion with the piezoelectric substrate is obviously enhanced.

Doping in the aluminium metal layer can make the piezoelectric effect of Al film obtain further improvement, and a small amount of doping element can improve Al's electromigration resistance for the orientation of Al film is better, but too high doping concentration can make the crystal quality of Al film worsen, and metallic aluminum's content is more than 97%, has the Al film of a small amount of doping material and has better microstructure and surface morphology, makes the performance of surface acoustic wave device excellent and stable.

Furthermore, the content of aluminum in the metal layer can be more than 98%, and the buffer layer also comprises one or more materials selected from Al, si and Mg. The purity of the metallic titanium buffer layer has a great influence on an Al thin film formed on the metallic titanium buffer layer, and under the condition that the metallic titanium buffer layer is relatively thin (below 0.5 percent lambda'), the metallic titanium buffer layer with higher purity is beneficial to forming a strong texture on the metallic Al thin film layer.

And a metal titanium buffer layer is formed between the Al metal layer and the piezoelectric film, so that the interface bonding strength of the electrode and the piezoelectric film is improved. When having avoided 5G high frequency application, the electrode finger vibration aggravation of interdigital transducer, the electrode drops from the base plate easily, causes the problem that the surface acoustic wave device became invalid.

In the present embodiment, as shown in FIGS. 4 to 5, the average film thickness H of the interdigital transducer 11 and the wavelength λ 'of the elastic wave determined by the electrode period of the interdigital transducer 11 satisfy 9% ≦ H/λ' ≦ 15%. The thickness of the interdigital transducer is related to the acoustic wave wavelength responded by the series resonator, so that the frequency offset of the surface acoustic wave filter can be restrained, and the insertion loss of the high-frequency side in a passband is reduced.

The average duty ratio of an interdigital transducer is defined as the ratio of the width W of each of a plurality of electrode fingers of the interdigital transducer to the sum of the width W of each of the plurality of electrode fingers and the distance G between the plurality of electrode fingers and an adjacent electrode finger, and is 0.5 or more and 0.7 or less.

It should be noted here that the manufacturing methods of the composite substrate shown in the drawings and described in the present specification are only a few examples of the many kinds of manufacturing methods of the composite substrate that can employ the principles of the present application. It should be clearly understood that the principles of this application are in no way limited to any of the details of the method of manufacturing a composite substrate or any of the components of the method of manufacturing a composite substrate shown in the drawings or described in this specification.

For a further understanding of the content of the present application, reference will now be made in detail to the present application with reference to specific embodiments. It should be noted that, for reasons of space, only some of the following examples are given, wherein the parameters of the manufacturing method and the like are not limited to the specific examples described below.

Example one

S1, providing a supporting substrate 101, wherein the supporting substrate 101 is provided with a first surface and a second surface which are oppositely arranged, and an isolating layer 102 is deposited on the first surface, and the acoustic velocity of the isolating layer 102 responding to the surface acoustic wave is lower than that of the supporting substrate 101 responding to the surface acoustic wave.

The support substrate is a monocrystalline silicon substrate, the isolation layer is of a single-layer structure, and the isolation layer is a monocrystalline silicon nitride film. The isolation layer is deposited on the first surface of the support substrate 101 by an epitaxial growth deposition method including: the reaction chamber and the supporting substrate 101 are heated, 100slm of nitrogen gas is introduced into the reaction chamber, the nitrogen gas is adsorbed on the first surface of the supporting substrate and reacts to generate a growing crystal SiN, and the growing crystal SiN sequentially moves on a crystal face to enter a crystal lattice and grows on the first surface in a diffusion mode.

And S2, providing the piezoelectric film substrate, and performing ion implantation on the surface of the piezoelectric film substrate to form a defect layer.

The piezoelectric film substrate is LiTaO3, the implanted ions are hydrogen ions, and the implantation dosage parameters are as follows: the implantation dose is 5 × 10 ¹⁶ ions/cm ² The implantation energy is 400keV. Thereby, the H + concentration reaches a peak at a distance of about 0.7 μm from the injection side of the piezoelectric thin film substrate, and a defect layer is formed in this region.

S3, cleaning and activating, removing impurities attached to the surface of the isolation layer 102 and the surface of the defect layer, and performing activation treatment on the surface of the isolation layer 102 and the surface of the defect layer;

s4, mechanical bonding, namely performing mechanical bonding treatment on the surface of the isolation layer 102 and the surface of the defect layer to form a substrate conjugant;

s5, stripping, namely heating the substrate conjugant at the stripping temperature of 100 ℃ in a vacuum environment to separate the substrate conjugant along the ion concentration peak of the defect layer (namely, the position of the piezoelectric film base plate which is about 0.7 mu m away from the injection side), so as to form a composite substrate with a partial defect layer;

s6, repairing the piezoelectric property, flattening the defect layer of the composite substrate, and annealing at the temperature 20 ℃ lower than the stripping temperature.

Example two

S1, providing a supporting substrate 101, wherein the supporting substrate 101 is provided with a first surface and a second surface which are oppositely arranged, an isolation layer 102 is deposited on the first surface, and the acoustic velocity of the isolation layer 102 responding to the surface acoustic wave is lower than that of the supporting substrate 101 responding to the surface acoustic wave.

The support substrate is glass, the isolation layer is of a single-layer structure, and the isolation layer is a single-crystal silicon nitride film. The isolation layer is deposited on the first surface of the support substrate 101 by an epitaxial growth deposition method including: the reaction chamber and the support substrate 101 are heated, 120slm of nitrogen gas is introduced into the reaction chamber, the nitrogen gas is adsorbed on the first surface of the support substrate and reacts to generate a growth crystal SiN, and the growth crystal SiN sequentially moves on a crystal face to enter a crystal lattice and grows on the first surface in a diffusion mode.

The piezoelectric film substrate is LiNbO3, the implanted ions are helium ions, and the implantation dosage parameters are as follows: the implantation dose is 5 × 10 ¹⁶ ions/cm ² The implantation energy is 400keV. Thus, the He + concentration reaches a peak at a distance of about 0.6 μm from the injection side of the piezoelectric thin film substrate, and a defect layer is formed in this region.

s5, stripping, heating the substrate conjugant at a stripping temperature of 130 ℃ in a vacuum environment, so that the substrate conjugant is separated along the ion concentration peak of the defect layer (namely, the position of the piezoelectric film base plate which is about 0.6 mu m away from the injection side), and a composite substrate with a partial defect layer is formed;

s6, repairing the piezoelectric property, flattening the defect layer of the composite substrate, and annealing at the temperature 50 ℃ lower than the stripping temperature.

EXAMPLE III

The supporting substrate is sapphire, the isolation layer is of a single-layer structure, and the isolation layer is a single-crystal silicon nitride film. The isolation layer is deposited on the first surface of the support substrate 101 by an epitaxial growth deposition method including: the reaction chamber and the supporting substrate 101 are heated, 140slm of nitrogen gas is introduced into the reaction chamber, the nitrogen gas is adsorbed on the first surface of the supporting substrate and reacts to generate a growing crystal SiN, and the growing crystal SiN sequentially moves on a crystal face to enter a crystal lattice and grows on the first surface in a diffusion mode.

The piezoelectric film substrate is Li2B4O7, the implanted ions are oxygen ions, and the implantation dosage parameters are as follows: the implantation dose is 5 × 10 ¹⁶ ions/cm ² The implantation energy is 400keV. Thereby, the O + concentration reaches a peak at a distance of about 0.8 μm from the injection side of the piezoelectric thin film substrate, and a defect layer is formed in this region.

s5, stripping, namely heating the substrate conjugant at the stripping temperature of 200 ℃ in a vacuum environment to separate the substrate conjugant along the ion concentration peak of the defect layer (namely, the position of the piezoelectric film base plate which is about 0.8 mu m away from the injection side), so as to form a composite substrate with a partial defect layer;

s6, repairing the piezoelectric property, flattening the defect layer of the composite substrate, and annealing at the temperature lower than the stripping temperature by 80 ℃.

Example four

The support substrate is a monocrystalline silicon substrate, the isolation layer is of a single-layer structure, and the isolation layer is a SiO3N2 film. The isolation layer is deposited on the first surface of the support substrate 101 by a pulsed magnetron sputtering deposition method, which comprises: placing a supporting substrate 101 and a silicon target material in a vacuum chamber, and introducing oxygen and nitrogen into the vacuum chamber, wherein the gas flow ratio of the oxygen to the nitrogen is 1-1 ² . Performing pulse magnetron sputtering to form SiO3N ₂ A film.

The piezoelectric film substrate is LiTaO3, the implanted ions are hydrogen ions, and the implantation dosage parameters are as follows: the implantation dose is 5 × 10 ¹⁶ ions/cm ² The implantation energy is 400keV. Thus, the H + concentration reaches a peak at a distance of about 0.7 μm from the injection side of the piezoelectric thin film substrate, and a defect layer is formed in this region.

s5, stripping, heating the substrate conjugant at the stripping temperature of 170 ℃ in a vacuum environment, so that the substrate conjugant is separated along the ion concentration peak of the defect layer (namely, the position of the piezoelectric film base plate which is about 0.7 mu m away from the injection side), and a composite substrate with a partial defect layer is formed;

s6, repairing the piezoelectric property, flattening the defect layer of the composite substrate, and annealing at the temperature 30 ℃ lower than the stripping temperature.

EXAMPLE five

Wherein the support substrate is SiC substrate, the isolation layer is of single-layer structure, and the isolation layer is SiO3N ₂ A film. The isolation layer is deposited on the first surface of the support substrate 101 by a pulsed magnetron sputtering deposition method, which comprises: placing a supporting substrate 101 and a silicon target material in a vacuum chamber, and introducing oxygen and nitrogen into the vacuum chamber, wherein the gas flow ratio of the oxygen to the nitrogen is 1-1 ² . Performing pulse magnetron sputtering to form SiO3N ₂ A film.

The piezoelectric film substrate is La3Ga5SiO14, the implanted ions are helium ions, and the implantation dosage parameters are as follows: the implantation dose is 5 × 10 ¹⁶ ions/cm ² The implantation energy is 400keV. Thus, the He + concentration reaches a peak at a distance of about 0.6 μm from the injection side of the piezoelectric thin film substrate, and a defect layer is formed in this region.

s5, stripping, namely heating the substrate conjugant at a stripping temperature of 180 ℃ in a vacuum environment to separate the substrate conjugant along the ion concentration peak of the defect layer (namely, the position of the piezoelectric film base plate which is about 0.6 mu m away from the injection side), so as to form a composite substrate with a partial defect layer;

s6, repairing the piezoelectric property, flattening the defect layer of the composite substrate, and annealing at the temperature 40 ℃ lower than the stripping temperature.

EXAMPLE six

The support substrate is a ceramic substrate, the isolation layer is of a single-layer structure, and the isolation layer is a SiO3N2 film. The isolation layer is deposited on the first surface of the supporting substrate 101 by a pulsed magnetron sputtering deposition method, which includes: placing a supporting substrate 101 and a silicon target material in a vacuum chamber, and introducing oxygen and nitrogen into the vacuum chamber, wherein the gas flow ratio of the oxygen to the nitrogen is 1-1 ² . And performing pulse magnetron sputtering to form the SiO3N2 film.

The piezoelectric film substrate is La3Ga5SiO14, the implanted ions are oxygen ions, and the implantation dosage parameters are as follows: the implantation dose is 5 × 10 ¹⁶ ions/cm ² The implantation energy is 400keV. Thereby, the O + concentration reaches a peak at a distance of about 0.6 μm from the injection side of the piezoelectric thin film substrate, and a defect layer is formed in this region.

s5, stripping, namely heating the substrate conjugant at the stripping temperature of 150 ℃ in a vacuum environment to separate the substrate conjugant along the ion concentration peak of the defect layer (namely, the position of the piezoelectric film base plate which is about 0.6 mu m away from the injection side), so as to form a composite substrate with a partial defect layer;

EXAMPLE seven

The supporting substrate is a quartz substrate, the isolation layer is of a single-layer structure, and the isolation layer is a SiO2N film. The isolation layer is deposited on the first surface of the support substrate 101 by a pulsed magnetron sputtering deposition method, which comprises: placing a supporting substrate 101 and a silicon target material in a vacuum chamber, and introducing oxygen and nitrogen into the vacuum chamber, wherein the gas flow ratio of the oxygen to the nitrogen is 1-1 ² . And performing pulse magnetron sputtering to form the SiO2N film.

s5, stripping, namely heating the substrate conjugant at a stripping temperature of 165 ℃ in a vacuum environment to separate the substrate conjugant along the ion concentration peak of the defect layer (namely, the position of the piezoelectric film base plate which is about 0.7 mu m away from the injection side), so as to form a composite substrate with a partial defect layer;

s6, repairing the piezoelectric property, flattening the defect layer of the composite substrate, and annealing at the temperature 25 ℃ lower than the stripping temperature.

Example eight

The support substrate is a sapphire substrate, the isolation layer is of a single-layer structure, and the isolation layer is an SiON film. The isolation layer is deposited on the first surface of the support substrate 101 by a pulsed magnetron sputtering deposition method, which comprises: placing a supporting substrate 101 and a silicon target material in a vacuum chamber, and introducing oxygen and nitrogen into the vacuum chamber, wherein the gas flow ratio of the oxygen to the nitrogen is 1-1 ² . And performing pulse magnetron sputtering to form the SiON film.

s5, stripping, namely heating the substrate conjugant at the stripping temperature of 140 ℃ in a vacuum environment to separate the substrate conjugant along the ion concentration peak of the defect layer (namely, the position of the piezoelectric film base plate which is about 0.7 mu m away from the injection side), so as to form a composite substrate with a partial defect layer;

s6, repairing the piezoelectric property, flattening the defect layer of the composite substrate, and annealing at the temperature of 25 ℃ lower than the stripping temperature.

Example nine

The support substrate is a sapphire substrate, the isolation layer is of a single-layer structure, and the isolation layer is an SiN film. The isolation layer is deposited on the first surface of the support substrate 101 by a plasma enhanced chemical vapor deposition method including: the supporting substrate 101 is placed in a vacuum chamber, nitrogen and silane are introduced into the vacuum chamber, wherein the gas flow ratio of nitrogen to silane is 1-1.

s5, stripping, heating the substrate conjugant at a stripping temperature of 240 ℃ in a vacuum environment, so that the substrate conjugant is separated along the ion concentration peak of the defect layer (namely, the position of the piezoelectric film base plate which is about 0.7 mu m away from the injection side), and a composite substrate with a partial defect layer is formed;

s6, repairing the piezoelectric property, flattening the defect layer of the composite substrate, and annealing at the temperature 60 ℃ lower than the stripping temperature.

Example ten

The supporting substrate is a sapphire substrate, the isolation layer is of a single-layer structure, and the isolation layer is a Si2N film. The isolation layer is deposited on the first surface of the support substrate 101 by a plasma enhanced chemical vapor deposition method including: the supporting substrate 101 is placed in a vacuum chamber, nitrogen and silane are introduced into the vacuum chamber, wherein the gas flow ratio of the nitrogen to the silane is 1-1.

s5, stripping, namely heating the substrate conjugant at the stripping temperature of 160 ℃ in a vacuum environment to separate the substrate conjugant along the ion concentration peak of the defect layer (namely, the position of the piezoelectric film base plate which is about 0.6 mu m away from the injection side), so as to form a composite substrate with a partial defect layer;

s6, repairing the piezoelectric property, flattening the defect layer of the composite substrate, and annealing at the temperature 65 ℃ lower than the stripping temperature.

EXAMPLE eleven

The supporting substrate is a sapphire substrate, the isolation layer is of a single-layer structure, and the isolation layer is an SiN10F film. The isolation layer is deposited on the first surface of the support substrate 101 by a plasma enhanced chemical vapor deposition method including: the supporting substrate 101 is placed in a vacuum chamber, and nitrogen gas and fluorine-containing compound gas are introduced into the vacuum chamber, wherein the gas flow ratio of the fluorine-containing compound gas to the nitrogen gas is 1. The fluorine-containing compound gas is tetrafluoroethylene, and plasma discharge is performed to generate plasma, thereby forming the SiN10F thin film.

s5, stripping, heating the substrate conjugant at the stripping temperature of 110 ℃ in a vacuum environment, so that the substrate conjugant is separated along the ion concentration peak of the defect layer (namely, the position of the piezoelectric film base plate which is about 0.7 mu m away from the injection side), and a composite substrate with a partial defect layer is formed;

s6, repairing the piezoelectric property, flattening the defect layer of the composite substrate, and annealing at the temperature 55 ℃ lower than the stripping temperature.

Example twelve

The supporting substrate is a sapphire substrate, the isolation layer is of a single-layer structure, and the isolation layer is an SiN10F film. The isolation layer is deposited on the first surface of the support substrate 101 by a plasma enhanced chemical vapor deposition method including: the supporting substrate 101 was placed in a vacuum chamber, and nitrogen gas and a fluorine-containing compound gas were introduced into the vacuum chamber, wherein the gas flow ratio of the fluorine-containing compound gas to the nitrogen gas was 1. The fluorine-containing compound gas is a mixture of trimethyl fluorosilane and octafluorobutene, and plasma discharge is performed to generate plasma, so that the SiN10F film is formed.

s5, stripping, namely heating the substrate conjugant at the stripping temperature of 230 ℃ in a vacuum environment to separate the substrate conjugant along the ion concentration peak of the defect layer (namely, the position of the piezoelectric film base plate which is about 0.7 mu m away from the injection side), so as to form a composite substrate with a partial defect layer;

s6, repairing the piezoelectric property, flattening the defect layer of the composite substrate, and annealing at the temperature lower than the stripping temperature by 85 ℃.

Thirteen examples

The supporting substrate is a sapphire substrate, the isolation layers are of a double-layer structure, the first isolation layer is a polycrystalline SiO2 film, and the second isolation layer is a single crystal Si3N4 film. And depositing the second isolating layer single crystal Si3N4 film on the surface of the supporting substrate by adopting an Atomic Layer Deposition (ALD) mode. The first isolating layer polycrystalline SiO2 film is deposited on the surface of the supporting substrate in a chemical vapor deposition mode.

s6, repairing the piezoelectric property, flattening the defect layer of the composite substrate, and annealing at the temperature 70 ℃ lower than the stripping temperature.

Example fourteen

The support substrate is a ceramic substrate, the isolation layers are of a double-layer structure, the first isolation layer is a polycrystalline SiO2 film, and the second isolation layer is a single crystal Si3N4 film. And the second isolating layer single crystal Si3N4 film is deposited on the surface of the supporting substrate in a single crystal epitaxial growth mode. The first isolating layer polycrystalline SiO2 film is deposited on the surface of the supporting substrate in a chemical vapor deposition mode.

s5, stripping, heating the substrate conjugant at the stripping temperature of 215 ℃ in a vacuum environment, so that the substrate conjugant is separated along the ion concentration peak of the defect layer (namely, the position of the piezoelectric film base plate which is about 0.7 mu m away from the injection side), and a composite substrate with a partial defect layer is formed;

s6, repairing the piezoelectric property, flattening the defect layer of the composite substrate, and annealing at the temperature lower than the stripping temperature by 70 ℃.

Example fifteen

Wherein, the supporting substrate is ceramic substrate, and the isolation layer is bilayer structure, including first isolation layer and sacrificial layer, the deposit isolation layer is: a first isolation layer is deposited on the first surface, and a sacrificial layer is deposited on the second surface, wherein the material, the thickness and the deposition process parameters of the sacrificial layer and the first isolation layer 1021 are the same. For example: the first isolation layer and the sacrificial layer are both polycrystalline SiO2 films or single crystal Si3N4 films and the like.

S3, cleaning and activating, removing impurities attached to the surface of the first isolation layer and the surface of the defect layer, and performing activation treatment on the surface of the first isolation layer and the surface of the defect layer;

s4, mechanical bonding, namely performing mechanical bonding treatment on the surface of the first isolation layer and the surface of the defect layer to form a substrate conjugant;

s5, stripping, namely heating the substrate conjugant at a stripping temperature of 250 ℃ in a vacuum environment to separate the substrate conjugant along the ion concentration peak of the defect layer (namely, the position of the piezoelectric film base plate which is about 0.7 mu m away from the injection side), so as to form a composite substrate with a partial defect layer;

s6, repairing the piezoelectric property, flattening the defect layer of the composite substrate, and annealing at the temperature 100 ℃ lower than the stripping temperature;

and S7, removing the sacrificial layer through a chemical mechanical polishing process.

Through the above embodiments of the method for manufacturing a composite substrate of the present application, it can be obtained that the method for manufacturing a composite substrate of the present application includes the steps of: and depositing an isolation layer, providing a support substrate, wherein the support substrate is provided with a first surface and a second surface which are oppositely arranged, the isolation layer is deposited on the first surface, and the sound velocity of the isolation layer responding to the surface acoustic wave is lower than that of the support substrate responding to the surface acoustic wave. The isolation layer is arranged through a deposition process, and the sound velocity of the isolation layer responding to the surface acoustic wave is lower than that of the support substrate responding to the surface acoustic wave, so that the leakage of the surface acoustic wave energy to the support substrate can be effectively reduced.

Performing ion implantation on the surface of the piezoelectric film substrate to form a defect layer; removing impurities attached to the surface of the isolation layer and the surface of the defect layer, and performing activation treatment on the surface of the isolation layer and the surface of the defect layer; and performing mechanical bonding treatment on the surface of the isolation layer and the surface of the defect layer to form a substrate joint body. The isolation layer has good flatness, provides a good joint surface for mechanical bonding treatment of the piezoelectric film substrate, reduces the problem of breakage of the piezoelectric film substrate and the supporting substrate due to stress mismatching, and improves the quality of the composite substrate.

And heating the substrate assembly at a stripping temperature in a vacuum environment, so that the substrate assembly is separated along the ion concentration peak of the defect layer to form a composite substrate with a partial defect layer. The isolation layer is arranged on the supporting substrate, so that the leakage of the longitudinal component of the surface acoustic wave to the single crystal supporting substrate can be effectively blocked, and the problem of mismatching of stress between the supporting substrate and the piezoelectric single crystal film is simultaneously relieved. At the defect layer, the crystallinity and piezoelectric characteristics of the piezoelectric single crystal of the piezoelectric thin film substrate are degraded by ion implantation, and therefore, it is necessary to perform piezoelectric characteristic repair on the crystallinity and piezoelectric characteristics of the composite substrate, to perform planarization treatment on the defect layer of the composite substrate, and to perform annealing treatment at a temperature between 0 and 100 ℃ lower than the peeling temperature.

In summary, in the manufacturing method of the composite substrate provided by the present application, the isolation layer is disposed between the piezoelectric thin film and the support substrate, so that the leakage of the longitudinal component of the surface acoustic wave to the single crystal support substrate can be effectively blocked, and the problem of stress mismatch between the support substrate and the piezoelectric single crystal thin film is simultaneously alleviated.

Exemplary embodiments of a composite substrate and a surface acoustic wave filter and a method of manufacturing the composite substrate proposed by the present application are described and/or illustrated in detail above. The embodiments of the application are not limited to the specific embodiments described herein, but rather, components and/or steps of each embodiment may be utilized independently and separately from other components and/or steps described herein. Each component and/or step of one embodiment can also be used in combination with other components and/or steps of other embodiments. When introducing elements/components/etc. described and/or illustrated herein, the articles "a," "an," "first," "second," and "the" etc. are intended to mean that there are one or more of the elements/components/etc. The terms "comprising," "including," and "having" are intended to be inclusive and mean that there may be additional elements/components/etc. other than the listed elements/components/etc.

The embodiments of the present application are not limited to the specific embodiments described herein, but rather, components of each embodiment may be utilized independently and separately from other components described herein. Each component of one embodiment can also be used in combination with other components of other embodiments. In the description herein, reference to the term "one embodiment," "some embodiments," "other embodiments," or the like, means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the embodiments. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The above description is only an alternative embodiment of the claimed embodiment and is not intended to limit the claimed embodiment, and various modifications and variations may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the applied embodiment shall be included in the protection scope of the applied embodiment.

Claims

1. A manufacturing method of a composite substrate for a surface acoustic wave filter, characterized by comprising the steps of:

s1, depositing an isolation layer: providing a support substrate, wherein the support substrate is provided with a first surface and a second surface which are oppositely arranged, the isolation layer is deposited on the first surface, and the sound velocity of the isolation layer responding to the surface acoustic wave is lower than that of the support substrate responding to the surface acoustic wave;

s3, cleaning and activating: removing impurities attached to the surface of the isolation layer and the surface of the defect layer, and performing activation treatment on the surface of the isolation layer and the surface of the defect layer;

s4, mechanical bonding: carrying out mechanical bonding treatment on the surface of the isolation layer and the surface of the defect layer to form a substrate conjugant;

s5, stripping: heating the substrate assembly at a lift-off temperature in a vacuum environment so that the substrate assembly separates along an ion concentration peak of the defect layer to form a composite substrate having a partial defect layer;

2. The method for manufacturing a composite substrate according to claim 1, wherein: the isolation layer is of a single-layer structure and is a single-crystal silicon nitride film.

3. The method for manufacturing a composite substrate according to claim 2, wherein: in step S1, the isolation layer is deposited on the first surface of the support substrate by an epitaxial growth deposition method, and the epitaxial growth deposition method includes: heating the reaction chamber and the supporting substrate, introducing nitrogen gas with a first gas flow rate into the reaction chamber, adsorbing the nitrogen gas on the first surface of the supporting substrate, reacting to generate a growth crystal SiN, moving the growth crystal SiN on the crystal surface in sequence to enter the crystal lattice, and growing on the first surface in a diffusion mode.

4. The method for manufacturing a composite substrate according to claim 1, wherein: step S6 comprises:

s6-3, flattening the defect layer by adopting a mechanical chemical polishing method, monitoring Raman spectrum values of the characteristic positions, and stopping chemical mechanical polishing when the difference between the average Raman spectrum value of the characteristic positions and the second Raman spectrum value is less than 10% of the second Raman spectrum value;

5. The method for manufacturing a composite substrate according to claim 1, wherein: the isolation layer is of a single-layer structure and is an SiOxNy film, wherein x/y is more than or equal to 1 and less than or equal to 2.

6. The method for manufacturing a composite substrate according to claim 5, wherein: in step S1, the isolation layer is deposited on the first surface of the support substrate by a pulsed magnetron sputtering deposition method, which includes: placing the support substrate and a silicon target material in a vacuum chamber, and introducing oxygen and nitrogen into the vacuum chamber, wherein the gas flow ratio of the oxygen to the nitrogen is 1.

7. The method for manufacturing a composite substrate according to claim 6, wherein: the thickness of the isolation layer is (0.5-1) lambda, wherein lambda refers to the wavelength of the surface acoustic wave filter responding to the surface acoustic wave.

8. The method for manufacturing a composite substrate according to claim 1, wherein: the isolation layer is of a single-layer structure and is made of SiN _a The film is characterized in that a is less than or equal to 1.1.

9. The method for manufacturing a composite substrate according to claim 8, wherein: in step S1, the isolation layer is deposited on the first surface of the support substrate by a plasma enhanced chemical vapor deposition method, where the plasma enhanced chemical vapor deposition method includes: and placing the support substrate in a vacuum chamber, introducing nitrogen and silane into the vacuum chamber, wherein the gas flow ratio of the nitrogen to the silane is 1-1.

10. The method for manufacturing a composite substrate according to claim 1, wherein: the isolation layer is of a single-layer structure and is made of SiN _a F _b The film, wherein b/a is more than or equal to 0.01 and less than or equal to 0.1.

11. The method for manufacturing a composite substrate according to claim 1, wherein: the isolation layer is bilayer structure, including first isolation layer and second isolation layer, the second isolation layer sets up supporting substrate with between the first isolation layer, the sound velocity of first isolation layer response surface acoustic wave is less than the sound velocity of second isolation layer response surface acoustic wave.

12. The method for manufacturing a composite substrate according to claim 1, wherein: in the step S1, the isolation layer includes a first isolation layer and a sacrificial layer, and depositing the isolation layer is: and depositing the first isolation layer on the first surface, and depositing the sacrificial layer on the second surface, wherein the material, the thickness and the deposition process parameters of the sacrificial layer and the first isolation layer are the same.

13. The method for manufacturing a composite substrate according to claim 12, wherein:

step S7 is also provided after step S6, and the sacrificial layer is removed by a chemical mechanical polishing process.

14. A composite substrate for a surface acoustic wave filter, characterized by: the composite substrate made by the method of any one of claims 1-10, the composite substrate comprising a piezoelectric film, an isolation layer, and a support substrate,

the isolation layer is single crystal silicon nitride; one of SiOxNy film, siNa film or SiNaFb film, wherein x/y is more than or equal to 1 and less than or equal to 2, a is more than or equal to 1.1, and b/a is more than or equal to 0.01 and less than or equal to 0.1.

15. A composite substrate for a surface acoustic wave filter, characterized by: the composite substrate made by the method of claim 11, the composite substrate comprising a piezoelectric film, a first isolation layer, a second isolation layer, and a support substrate,

16. A surface acoustic wave filter includes an interdigital transducer and a composite substrate, and is characterized in that: the composite substrate as claimed in any one of claims 14 to 15, the interdigital transducer being disposed on a surface of the piezoelectric film of the composite substrate remote from the support base plate.

17. A surface acoustic wave filter as set forth in claim 16, wherein: the interdigital transducer includes:

a buffer layer disposed on the piezoelectric film of the composite substrate, the buffer layer including metallic titanium, the buffer layer having a thickness of 0.5% λ 'or less, where λ' represents a wavelength of an elastic wave determined by an electrode period of the interdigital transducer;

the metal layer is arranged on the surface of the buffer layer far away from the piezoelectric film and comprises aluminum, wherein the content of the aluminum is more than 95wt%, the metal layer further comprises one or more materials selected from Cu, W, mo, cr, ag, pt, ga, nb, ta, au and Si, and the thickness of the metal layer is between 1% lambda 'and 30% lambda'.

18. A surface acoustic wave filter as set forth in claim 17, wherein: the average film thickness H of the interdigital transducer and the wavelength lambda 'of the elastic wave determined by the electrode period of the interdigital transducer satisfy 9% H/lambda' 15%.