Blackened single crystal piezoelectric composite film based on plasma etching and preparation method thereof

Abstract

The present application discloses a blackened single-crystal piezoelectric composite film based on plasma etching and a preparation method thereof, comprising preparing a piezoelectric wafer and a substrate, wherein the piezoelectric wafer is a lithium niobate wafer or a lithium tantalate wafer; utilizing an ion implantation-bonding method or a bonding-grinding and polishing method to prepare a single-crystal piezoelectric composite film, wherein the single-crystal piezoelectric composite film comprises a substrate and a film layer of target thickness stacked in sequence; performing plasma etching on the film layer in the single-crystal piezoelectric composite film, wherein the plasma used for the plasma etching treatment comprises a reducing plasma and / or an inert plasma; and performing grinding and polishing on the blackened film layer to obtain a blackened single-crystal piezoelectric composite film. By treating the film layer with the plasma etching method, the oxygen vacancy concentration in the film layer is increased, thereby repairing the blackening of the film layer or inhibiting the whitening of the film layer.

Description

Technical Field

[0001] The present application relates to the field of semiconductor preparation, and in particular to a blackened single-crystal piezoelectric composite film based on plasma etching and a preparation method thereof. Background Art

[0002] Lithium niobate and lithium tantalate crystals have been widely used in various core electronic components such as surface acoustic wave devices, thin film bulk acoustic wave resonators, photoelectric sensors, etc. due to their various excellent optical properties, such as piezoelectric, ferroelectric, photoelectric, photoelastic, pyroelectric, photorefractive and nonlinear optical properties.

[0003] Because lithium niobate and lithium tantalate crystals are both ferroelectric crystals, they have high pyroelectric coefficients and resistivities. Consequently, when using lithium niobate and lithium tantalate wafers to manufacture electronic components, a large amount of static charge easily accumulates on their surfaces. The release of this static charge can damage the wafers, thereby affecting the performance and yield of the resulting electronic components.

[0004] To solve the above problems, in one implementation, lithium niobate and lithium tantalate wafers are pre-blackened. The blackening treatment refers to treating lithium niobate and lithium tantalate wafers through methods such as high-temperature chemical reduction to reduce the pyroelectric effect and resistivity of the lithium niobate and lithium tantalate wafers. After the blackening treatment, the lithium niobate and lithium tantalate wafers will change from a colorless and transparent state to a brown color. Furthermore, the use of blackened lithium niobate and lithium tantalate wafers to prepare electronic components can solve the problem that the release of static charge will damage the lithium niobate or lithium tantalate wafers.

[0005] However, the applicant found that for electronic components using piezoelectric composite films, although lithium niobate and lithium tantalate wafers that had been pre-blackened were used, the film whitening phenomenon caused by high-temperature annealing still occurred during the preparation of the composite film. Therefore, when the prepared piezoelectric composite film was used in electronic components, there was still a phenomenon of static charge release damaging the electronic components. Summary of the Invention

[0006] In order to solve the above technical problems, the present application provides a blackened single-crystal piezoelectric composite film based on plasma etching and a preparation method thereof.

[0007] In a first aspect, the present application provides a method for preparing a blackened single-crystal piezoelectric composite film based on plasma etching, comprising:

[0008] Preparing a piezoelectric wafer and a substrate, wherein the piezoelectric wafer is a lithium niobate wafer or a lithium tantalate wafer;

[0009] A single-crystal piezoelectric composite film is prepared by an ion implantation-bonding method or a bonding-thinning method, wherein the single-crystal piezoelectric composite film comprises a substrate and a thin film layer of a target thickness stacked in sequence;

[0010] Plasma etching is performed on the thin film layer in the single crystal piezoelectric composite thin film to obtain a blackened single crystal piezoelectric composite thin film, wherein the plasma used in the plasma etching treatment includes reducing plasma and / or inert plasma.

[0011] In one possible implementation, a single crystal piezoelectric composite film is prepared by an ion implantation-bonding method, including:

[0012] Implanting ions into the piezoelectric wafer by an ion implantation method to sequentially divide the piezoelectric wafer into a residual layer, a separation layer, and a thin film layer;

[0013] Bonding the piezoelectric wafer to the substrate to obtain a bonded body;

[0014] The bonded body is heat-treated to separate the residual material layer from the thin film layer, thereby obtaining a single crystal piezoelectric composite thin film.

[0015] In one possible implementation, a single crystal piezoelectric composite film is prepared using a bonding-thinning method, including:

[0016] Bonding the piezoelectric wafer and the substrate to obtain a bonded body;

[0017] heat-treating the bonded body to obtain a single crystal piezoelectric composite thin film prefabricated body;

[0018] The piezoelectric wafer in the single crystal piezoelectric composite thin film prefabrication is thinned to form a thin film layer of target thickness on the substrate.

[0019] In one achievable embodiment, the plasma etching treatment of the thin film layer in the single crystal piezoelectric composite thin film includes: plasma etching from the surface of the thin film layer to the inside of the thin film layer, wherein the etching depth is greater than zero and less than the thickness of the thin film layer.

[0020] In one achievable manner, the thickness of the blackened thin film layer ground and polished is greater than or equal to the etching depth and less than the thickness of the blackened thin film layer.

[0021] In one possible implementation, a plasma etching method is used to perform plasma etching on the surface of the thin film layer in the single crystal piezoelectric composite thin film, including:

[0022] In the reaction chamber, the reaction gas is ionized under the excitation of the radio frequency power source and forms a plasma, wherein the plasma includes reducing plasma and / or inert plasma;

[0023] The plasma etches the thin film layer to increase the oxygen vacancy concentration in the thin film layer, wherein the temperature in the reaction chamber is 0-600° C. and the etching time is 5 minutes to 20 hours.

[0024] In one implementation, the gas pressure in the reaction chamber is 1 Pa-100 Pa, and the etching bias voltage is 100-5000 V.

[0025] In one implementation, the reducing plasma includes at least one of hydrogen ions, carbon ions, and reducing metal ions.

[0026] In one implementation, if the reducing plasma includes hydrogen ions, the reaction gas selected for the plasma etching process is hydrogen; if the reducing plasma includes carbon ions, the reaction gas selected for the plasma etching process is methane.

[0027] In one implementation, the inert plasma includes at least one of neon ions and argon ions.

[0028] In one implementation, the substrate is a single-layer substrate or a composite substrate.

[0029] In a second aspect, the present application provides a blackened single-crystal piezoelectric composite film, which is prepared by any of the methods for preparing a blackened single-crystal piezoelectric composite film based on plasma etching described in the first aspect.

[0030] In summary, the blackened single-crystal piezoelectric composite film based on plasma etching and its preparation method provided by the present application treats the thin film layer by the plasma etching method to increase the oxygen vacancy concentration in the thin film layer, thereby repairing the blackening of the thin film layer or inhibiting the whitening of the thin film layer. Compared with the method of blackening the thin film layer by laying reducing powder on the surface of the thin film layer, the advantages of blackening the thin film layer by the plasma etching method of the present application are: the particle size of the plasma is much smaller than the particle size of the reducing powder. Therefore, first, compared with the reducing powder, the plasma can contact the thin film layer more evenly; second, when the blackened thin film layer is ground and polished, the plasma is easier to be processed than the reducing powder. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1 A flow chart of a method for preparing a blackened single-crystal piezoelectric composite film based on plasma etching provided in an embodiment of the present application;

[0033] Figure 2 A flow chart of another method for preparing a blackened single-crystal piezoelectric composite film based on plasma etching provided in an embodiment of the present application.

[0034] Description of Reference Numerals

[0035] 100 - piezoelectric wafer, 110 - residual material layer, 120 - separation layer, 130 - thin film layer, 130A - blackened thin film layer, 200 - substrate, 300 - bonding body. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of this application.

[0037] As introduced in the background technology section, in order to solve the technical problem that a large amount of static charge is easily accumulated on the surface of lithium niobate and lithium tantalate wafers, and the release of these static charges will damage the lithium niobate and lithium tantalate wafers, the lithium niobate and lithium tantalate wafers are usually blackened in advance, and then the blackened lithium niobate and lithium tantalate wafers are used to prepare piezoelectric composite films.

[0038] However, the applicant discovered that when the piezoelectric composite film is applied to electronic components, the release of static charge still causes damage to the electronic components. Based on this, the applicant conducted further research and analysis and found that: during the preparation of the piezoelectric composite film, after the lithium niobate or lithium tantalate film layer is separated from the residual layer, the bond between the film layer and the substrate wafer is subjected to high-temperature annealing to further strengthen the bonding force and eliminate lattice defects formed in the film layer during the ion implantation process. However, the applicant discovered that during the high-temperature annealing process, the film layer, which should be brown, partially or completely whitens. In other words, the originally blackened film layer in the final composite film material regains its high pyroelectric coefficient and resistivity, thereby affecting the performance of the electronic components to which it is applied.

[0039] Based on the above analysis, an embodiment of the present application provides a method for preparing a blackened single-crystal piezoelectric composite film, which can solve the technical problem that the piezoelectric composite film prepared using blackened lithium niobate or lithium tantalate wafers still has the problem of static charge release damaging electronic components.

[0040] The following is a detailed description of a method for preparing a blackened single crystal piezoelectric composite film provided in an embodiment of the present application.

[0041] like Figure 1 As shown, the embodiment of the present application provides a method for preparing a blackened single crystal piezoelectric composite film, comprising the following steps:

[0042] Step 100: Prepare a piezoelectric wafer 100 and a base substrate 200, wherein the piezoelectric wafer 100 is a lithium niobate wafer or a lithium tantalate wafer.

[0043] In the embodiment of the present application, the piezoelectric wafer 100 refers to a base material with a certain thickness for preparing a thin film layer. The piezoelectric wafer can be a wafer that has not been blackened, or a wafer that has been blackened, and this application does not limit this. If the piezoelectric wafer is a wafer that has been blackened, the piezoelectric wafer 100 can be obtained by direct purchase; or, the piezoelectric wafer 100 can be obtained by blackening a directly purchased lithium niobate wafer that has not been blackened or a lithium tantalate wafer that has not been blackened, wherein the blackening method for the lithium niobate wafer or the lithium tantalate wafer can adopt any existing feasible blackening method, and this application does not limit this.

[0044] In the embodiments of the present application, the substrate 200 can be a single-layer substrate or a composite substrate, i.e., the substrate 200 includes at least one substrate layer. The materials of each substrate layer can be the same or different, and this application does not limit this. For example, the substrate layer material can be lithium niobate, lithium tantalate, quartz, silicon, sapphire, SOI, diamond, silicon carbide, silicon nitride, gallium arsenide, or indium phosphide, and this application does not limit this.

[0045] Step 200: Prepare a single-crystal piezoelectric composite film by using an ion implantation-bonding method or a bonding-thinning method, wherein the single-crystal piezoelectric composite film includes a substrate and a film layer of target thickness stacked in sequence.

[0046] The present application provides two methods for preparing single-crystal piezoelectric composite films. The first method is an ion implantation-bonding method, and the second method is a bonding-thinning method. The two methods for preparing single-crystal piezoelectric composite films are introduced below.

[0047] like Figure 1 As shown, a single crystal piezoelectric composite film is prepared by an ion implantation-bonding method, which includes the following steps:

[0048] Step 210 : Ions are implanted into the piezoelectric wafer 100 by an ion implantation method, so as to sequentially separate the piezoelectric wafer 100 into a residual layer 110 , a separation layer 120 , and a thin film layer 130 .

[0049] The present invention does not specifically limit the method of ion implantation. Any ion implantation method in the prior art can be used. The implanted ions can be ions that can generate gas through heat treatment. For example, the implanted ions can be hydrogen ions, helium ions, nitrogen ions, oxygen ions, or argon ions. When implanting ions, the implantation dose can be 2×10 16 ions / cm 2 ~4×10 16 ions / cm 2 The injection energy may be 40 KeV to 400 KeV, for example, the injection energy is 50 KeV.

[0050] In the embodiment of the present application, the thickness of the thin film layer 130 can be adjusted by adjusting the ion implantation depth. Specifically, the greater the depth of the ion implantation, the greater the thickness of the prepared thin film layer 130; conversely, the smaller the depth of the ion implantation, the smaller the thickness of the prepared thin film layer 130.

[0051] Step 220 : Bond the piezoelectric wafer 100 to the base substrate 200 to obtain a bonded body 300 .

[0052] After bonding, the thin film layer 130 of the piezoelectric wafer 100 contacts the base substrate 200 and is stacked on the base substrate 200 . Thus, the bonded body 300 is stacked with the residual layer 110 , the separation layer 120 , the thin film layer 130 and the base substrate 200 from top to bottom.

[0053] The present application does not specifically limit the bonding method, and any bonding method in the prior art may be used, for example, bonding by surface activation to obtain a bonded body. The present application also does not limit the surface activation method, for example, plasma activation or chemical solution activation may be used.

[0054] It should be noted that the present application may also include a step of preparing an isolation layer on the base substrate 200 before step 300. For example, if the base substrate 200 is a single-layer silicon substrate, silicon oxide can be prepared on the single-layer silicon substrate by thermal oxidation, and the resulting silicon oxide layer serves as the isolation layer. In this way, in step 300, the piezoelectric wafer 100 is bonded to the base substrate 200 having the isolation layer to obtain a bonded body.

[0055] It should also be noted that the isolation layer prepared on the base substrate 200 can be a single layer or multiple layers, which is not limited in this application. For example, silicon oxide layers and silicon nitride layers stacked alternately are prepared on the base substrate 200.

[0056] Step 230 : heat-treating the bonded body 300 to separate the residual layer 110 from the thin film layer 130 , thereby obtaining a single crystal piezoelectric composite thin film.

[0057] The bonding body 300 is heat-treated, and the heat treatment process can be kept warm at 180-280°C for 1-100 hours. During the heat treatment, bubbles are formed in the separation layer 120, for example, H ions form hydrogen, He ions form helium, etc. As the heat treatment progresses, the bubbles in the separation layer 120 are connected together, and finally the separation layer 120 is cracked, separating the residual layer 110 from the thin film layer 130, so that the residual layer 110 is peeled off from the bonding body 300 to obtain a single crystal piezoelectric composite film, wherein the single crystal piezoelectric composite film is stacked with a thin film layer 130 and a base substrate 200 in sequence from top to bottom.

[0058] like Figure 2 As shown, a single crystal piezoelectric composite film is prepared by a bonding-thinning method, which includes the following steps:

[0059] Step 310: Bond the piezoelectric wafer and the substrate to obtain a bonded body.

[0060] In the bonding-grinding and polishing method, the piezoelectric wafer is directly bonded to the base substrate. The method of bonding the piezoelectric wafer to the base substrate can be referred to the description of step 220 and will not be repeated here.

[0061] Step 320 : heat-treating the bonded body to obtain a single crystal piezoelectric composite thin film prefabricated body.

[0062] In the bonding-grinding and polishing method, the purpose of heat treatment of the bonded body is to enhance the bonding force between the piezoelectric wafer and the substrate. The present application does not limit the heat treatment process conditions in step 320. For example, the heat treatment process conditions may be keeping warm at 180-280°C for 1-100 hours.

[0063] Step 330 : Thinning the piezoelectric wafer in the single crystal piezoelectric composite thin film prefabrication to form a thin film layer of target thickness on the substrate.

[0064] This application does not limit the specific thinning method used, and thinning by, for example, grinding and polishing or mechanical cutting may be employed. The piezoelectric wafer in the single crystal piezoelectric composite thin film prefabrication is thinned until a thin film layer of a target thickness is formed on the substrate. It should be understood that the thin film layer is made of the same material as the piezoelectric wafer, but is much thinner than the thickness of the piezoelectric wafer before grinding and polishing.

[0065] When the piezoelectric wafer is a lithium niobate wafer or a lithium tantalate wafer that has undergone a blackening treatment, the applicant has discovered that after the aforementioned step 230, the film layer 130 in the single-crystal piezoelectric composite thin film, which should be brown, is partially or completely whitened. Furthermore, after the aforementioned step 320, the piezoelectric wafer in the single-crystal piezoelectric composite thin film prefabricated body, which should be brown, is partially or completely whitened. This indicates that after the bonded body is heat treated, the originally blackened film layer 130 or the piezoelectric wafer is partially or completely oxidized. To correct this phenomenon, the applicant proposes to blacken the film layer by plasma etching the prepared film layer.

[0066] It should be noted that when the piezoelectric wafer is a lithium niobate wafer or a lithium tantalate wafer that has not been blackened, the thin film layer can also be plasma etched after the single crystal piezoelectric composite film is prepared to blacken the thin film layer. In this way, it can be ensured that the thin film layer 130 in the blackened single crystal piezoelectric composite film finally prepared is in a completely blackened state.

[0067] The following describes the method provided in the present application for blackening the thin film layer in the single crystal piezoelectric composite thin film.

[0068] Step 400 , performing plasma etching on the thin film layer 130 in the single crystal piezoelectric composite thin film to blacken the thin film layer, thereby obtaining a blackened single crystal piezoelectric composite thin film, wherein the plasma used in the plasma etching treatment includes reducing plasma and / or inert plasma.

[0069] Plasma etching of thin film layers requires the use of plasma etching equipment. Within the plasma etching chamber, the reactive gas, excited by a radio frequency power source, ionizes and forms a plasma, which is composed of charged electrons and positive ions. The plasma then diffuses to the desired location and performs the etching process.

[0070] Thus, when the present application utilizes a plasma etching method to treat a thin film layer, the plasma is bombarded onto the surface of the thin film layer and can further diffuse to a certain depth from the surface of the thin film layer. For ease of description, the depth of plasma diffusion from the surface of the thin film layer into the interior of the thin film layer is referred to as the etching depth. The etching depth of the plasma etching process from the surface of the thin film layer into the interior of the thin film layer in the present application is greater than zero and less than the thickness of the thin film layer. Generally, the etching depth is tens to hundreds of nanometers.

[0071] The purpose of performing plasma etching on the thin film layer in the single crystal piezoelectric composite thin film in the present application is to blacken the thin film layer, which can be achieved specifically in the following three ways.

[0072] The first implementation method is based on the principle of chemical etching. In this implementation method, the plasma used in the plasma etching process is a reducing plasma. In this way, after the reducing plasma contacts the thin film layer, it can undergo a reduction reaction with the oxygen in the thin film layer, thereby forming oxygen vacancies at the location where oxygen originally existed. As the reaction proceeds, the oxygen in the thin film layer will diffuse from the location with high oxygen concentration to the location with low oxygen concentration. In other words, the oxygen below the thin film layer gradually diffuses to the top of the thin film layer. In this way, the oxygen diffused to the top of the thin film layer is gradually reduced by the reducing plasma, thereby forming more oxygen vacancies in the thin film layer. Therefore, after the thin film layer in the single crystal piezoelectric composite film is plasma etched, the oxygen vacancy concentration increases and the resistivity decreases, achieving the blackening of the thin film layer.

[0073] The present application does not limit the reducing plasma, as long as it can react with oxygen in the thin film layer to form oxygen vacancies. For example, the reducing plasma can be at least one of hydrogen ions, carbon ions and reducing metal ions. That is to say, the reducing plasma can be hydrogen ions, carbon ions, reducing metal ions, or a mixture of two or three of hydrogen ions, carbon ions and reducing metal ions. Among them, the reaction gas for generating hydrogen ions can be hydrogen, and the reaction gas for generating carbon ions can be methane. In this way, hydrogen is ionized and forms hydrogen ions under the excitation of the radio frequency power source; methane is ionized and forms carbon ions under the excitation of the radio frequency power source. Among them, the reducing metal ions can be Zn 2+ 、Fe 2+ 、Cu 2+ Mg 2+ This application does not limit this.

[0074] The second possible implementation is based on the principle of physical etching. In this implementation, the plasma used for plasma etching is an inert plasma. In this way, when the high-energy plasma is projected onto the surface of the thin film layer, energy and momentum transfer will occur between the high-energy plasma and the atoms collided in the thin film layer through collision, thereby causing the atoms to be disturbed. If the energy transferred by the bombarding ions (i.e., plasma) to the atoms to be collided is greater than the original binding energy (from a few eV to dozens of eV), the atoms to be collided will be separated from their original positions and splashed out. Among them, the factors affecting the level of plasma energy include bias voltage and plasma quality. Therefore, in this application, at least one of neon ions and argon ions is selected as the inert plasma. In this way, in the etching bias range of 100-5000V, the neon ions and argon ions generated in the discharge have energies of more than 500eV, which is greater than the binding energy of oxygen. Therefore, when this high-energy ion beam bombards the surface of the thin film layer, oxygen will be separated from its original position and splashed out, achieving the blackening of the thin film layer.

[0075] In the present application, the inert plasma may be at least one of neon ions and argon ions. Correspondingly, the reaction gas for generating neon ions may be neon gas, and the reaction gas for generating argon ions may be argon gas.

[0076] In a third implementation, the plasma used in the plasma etching process may include both reducing plasma and inert plasma. The reducing plasma in the plasma can increase oxygen vacancies in the film layer by undergoing a reduction reaction with oxygen in the film layer. For details, refer to the description of the first implementation and will not be repeated here. Meanwhile, the inert plasma in the plasma can increase oxygen vacancies in the film layer by physical bombardment. For details, refer to the description of the second implementation and will not be repeated here.

[0077] It should be noted that the depth of plasma etching is relatively small, generally tens to hundreds of nanometers, so it is widely used in the preparation of integrated circuit patterns. Since the thickness of the thin film layer is generally not too large, generally, the ion implantation-bonding method can be used to prepare a nanometer-scale thin film layer, for example, the thickness of the thin film layer is 300nm-900nm; the bonding-grinding and polishing method can be used to prepare a micron-scale thin film layer, for example, the thickness of the thin film layer is 1-10μm. Therefore, even if the plasma etching method with a relatively small etching depth is used to treat the thin film layer, it is sufficient to blacken the thin film layer. At the same time, since the thickness of the thin film layer is relatively small, when the temperature in the reaction chamber is 0-600℃, the thin film layer can be completely blackened by etching for 5 minutes to 20 hours. Among them, the higher the temperature in the reaction chamber, the shorter the etching time required.

[0078] It should also be noted that this application does not limit the processing parameters of thin film layer plasma etching processing. For example, the gas pressure in the reaction chamber is 1Pa-100Pa, and the etching bias is 100-5000V. During specific implementation, the corresponding etching bias can be calculated according to the desired etching depth.

[0079] After the processing in step 400 , the thin film layer 130 in the single crystal piezoelectric composite thin film is blackened, and the surface resistivity is reduced, thereby obtaining a blackened single crystal piezoelectric composite thin film.

[0080] After the thin film layer in the single-crystal piezoelectric composite film is treated with plasma etching, certain damage may be formed in the part where the plasma contacts the thin film layer, and some plasma residue may exist on the thin film layer. Therefore, after step 400, the following step 500 may be included, in which the blackened thin film layer is further ground and polished to obtain a blackened thin film layer without damage and with flatness that meets the requirements, wherein the thickness of the blackened thin film layer ground and polished is greater than or equal to the etching depth of the plasma etching treatment and less than the thickness of the blackened thin film layer.

[0081] Step 500: Grinding and polishing the blackened thin film layer to obtain a blackened single crystal piezoelectric composite thin film.

[0082] It should be noted that compared with the method of blackening the thin film layer by laying reducing powder on the surface of the thin film layer, the advantage of blackening the thin film layer by plasma etching method in the present application is that: the particle size of the plasma is much smaller than the particle size of the reducing powder. Therefore, first, compared with the reducing powder, the plasma can contact the thin film layer more evenly; second, when the blackened thin film layer is ground and polished, the plasma is easier to be disposed of than the reducing powder.

[0083] The blackened single crystal piezoelectric composite film prepared in step 500 of the present application includes a stacked blackened film layer 130A and a base substrate 200 .

[0084] It should be understood that when preparing a blackened single-crystal piezoelectric composite film, the thickness of the thin film layer prepared in step 200 and the etching depth can be calculated in advance based on the thickness of the blackened thin film layer in the final blackened single-crystal piezoelectric composite film, wherein the thickness of the thin film layer prepared in step 200 should be greater than the thickness of the blackened thin film layer, and the etching depth should satisfy: the depth of the thin film layer prepared in step 200 that is not etched by plasma is greater than or equal to the thickness of the blackened thin film layer.

[0085] In summary, the preparation method of the blackened single-crystal piezoelectric composite film provided in the present application is to blacken the thin film layer after bonding treatment. Specifically, the thin film layer is treated by a plasma etching method to increase the oxygen vacancy concentration in the thin film layer, thereby repairing the blackening of the thin film layer or inhibiting the whitening of the thin film layer.

[0086] The present application also provides a blackened single crystal piezoelectric composite film, which is obtained by using the preparation method provided in the above embodiment.

[0087] In one possible implementation, the present application provides a blackened single-crystal piezoelectric composite film, comprising a blackened film layer and a base substrate stacked in sequence, wherein the base substrate may be a single-layer substrate or a composite substrate.

[0088] In yet another possible implementation, the present application provides a blackened single-crystal piezoelectric composite film, which may further include one or more isolation layers between the blackened film layer and the base substrate.

[0089] The present application also provides an electronic component that utilizes the blackened single-crystal piezoelectric composite thin film provided in the embodiments of the present application. The thin film layer in the blackened single-crystal piezoelectric composite thin film provided in the embodiments of the present application is repaired through plasma etching, effectively reducing the pyroelectric effect of the single-crystal piezoelectric composite thin film, thereby not affecting the performance of the electronic component during use.

[0090] The following experimental data illustrates the technical effects of the plasma etching method for preparing a blackened single-crystal piezoelectric composite thin film, as provided in the examples of this application. Each set of experimental examples utilizes the preparation method provided herein to prepare a blackened single-crystal piezoelectric composite thin film, while each set of comparative examples includes only steps 100 and 200 of the preparation method provided herein, i.e., no further plasma etching of the single-crystal piezoelectric composite thin film is performed. The parameters for each set of experimental examples and comparative examples are shown in Table 1.

[0091] Table 1 Experimental parameters and experimental results

[0092]

[0093] The preparation method provided in this application is described below through specific examples.

[0094] Example 1

[0095] Example 1 provides a method for preparing a blackened single-crystal piezoelectric composite film based on plasma etching, comprising the following steps:

[0096] 1. Prepare a 200μm silicon wafer and a 200μm lithium niobate wafer. Fix the silicon wafer or lithium niobate on the porous ceramic chuck of the polishing equipment respectively, perform chemical mechanical polishing to obtain a smooth surface, and then perform semiconductor RCA cleaning on both wafers to obtain a clean surface. Among them, the lithium niobate wafer is a lithium niobate wafer that has been blackened.

[0097] 2. The lithium niobate wafer processed in step 1 is implanted with He using the stripping ion implantation method. + , so that the lithium niobate wafer is divided into residual layer, separation layer and thin film layer in sequence starting from the implantation surface. + Distributed in the separation layer, a single crystal lithium niobate wafer implantation piece is obtained.

[0098] He was implanted using the stripping ion implantation method. + When the injection dose parameters are: injection dose is 2×10 16 ions / cm 2 , the injection energy is 40keV, and the injection depth is 220nm.

[0099] 3. A silicon dioxide layer was formed on the cleaned silicon wafer using the LPCVD method, and then chemical mechanical polishing was performed to a thickness of 100 nm to obtain a smooth surface, and RCA cleaning was performed to obtain a clean surface.

[0100] 4. The thin film layer of the single crystal lithium niobate wafer implant is brought into contact with the silicon dioxide layer and bonded using a direct bonding method to obtain a bonded body.

[0101] 5. Under nitrogen atmosphere, place the bonded body in an annealing furnace and keep it at 180°C for 2 hours. The bonded body is broken and separated at the separation layer to obtain a single crystal piezoelectric composite film.

[0102] 6. Perform plasma etching on the thin film layer in the single crystal piezoelectric composite film, wherein the plasma used in the plasma etching treatment includes hydrogen ions, and the etching condition parameters are: under vacuum conditions, etching pressure 100 Pa, etching bias 5000 V, and etching at 25°C for 20 hours.

[0103] 7. Fix the above-mentioned single crystal piezoelectric composite film on the porous ceramic chuck of the polishing equipment, perform chemical mechanical polishing on the blackened film layer until the hydrogen ions on the surface of the film layer are removed, and then perform RCA cleaning to obtain a clean surface.

[0104] The obtained blackened single crystal piezoelectric composite film sequentially comprises a blackened single crystal film layer, a silicon dioxide layer and a single crystal silicon layer.

[0105] Example 2

[0106] Example 2 provides a method for preparing a blackened single-crystal piezoelectric composite film based on plasma etching, comprising the following steps:

[0107] 1. Prepare a 500μm silicon carbide wafer and a 500μm lithium tantalate wafer. Fix the silicon carbide wafer or lithium tantalate on the porous ceramic chuck of the polishing equipment respectively, perform chemical mechanical polishing to obtain a smooth surface, and then perform semiconductor RCA cleaning on both wafers to obtain a clean surface; among them, the lithium tantalate wafer is a lithium tantalate wafer that has been blackened.

[0108] 2. Nitrogen ions are implanted into the lithium tantalate wafer after the treatment in step 1 by using the stripping ion implantation method, so that the lithium tantalate wafer is divided into a residual layer, a separation layer and a thin film layer in sequence starting from the implantation surface. The implanted nitrogen ions are distributed in the separation layer to obtain a single crystal lithium tantalate wafer implantation sheet.

[0109] When the stripping ion implantation method is used to implant nitrogen ions, the implantation dose parameters are: the implantation dose is 2×10 16 ions / cm 2 , the injection energy is 50keV.

[0110] 3. Amorphous silicon with a thickness of 10 μm is produced on the cleaned silicon carbide wafer using the PVD method.

[0111] 4. A silicon dioxide layer was formed on the amorphous silicon layer by PVD method, and then chemical mechanical polishing was performed to obtain a smooth surface with a thickness of 10 μm, and RCA cleaning was performed to obtain a clean surface.

[0112] 5. The thin film layer of the single crystal lithium tantalate wafer implant is brought into contact with the silicon dioxide layer and bonded using a direct bonding method to obtain a bonded body.

[0113] 6. Under a hydrogen atmosphere, place the bonded body in an annealing furnace and keep it at 280°C for 4 hours. The bonded body is broken and separated at the separation layer to obtain a single crystal piezoelectric composite film.

[0114] 7. Perform plasma etching on the thin film layer in the single crystal piezoelectric composite film, wherein the plasma used in the plasma etching treatment includes carbon ions, and the etching condition parameters are: under vacuum conditions, etching pressure 50 Pa, etching bias 1000 V, and etching at 0°C for 1 hour.

[0115] 8. Fix the above-mentioned single crystal piezoelectric composite film on the porous ceramic chuck of the polishing equipment, perform chemical mechanical polishing on the blackened film layer until the hydrogen ions on the surface of the film layer are removed, and then perform RCA cleaning to obtain a clean surface.

[0116] The obtained blackened single crystal piezoelectric composite film sequentially comprises a blackened single crystal film layer, a silicon dioxide layer, a polysilicon layer and a silicon carbide layer.

[0117] Example 3

[0118] Example 3 provides a method for preparing a blackened single-crystal piezoelectric composite film based on plasma etching, comprising the following steps:

[0119] 1. Prepare a 200μm silicon nitride wafer and a 250μm lithium niobate wafer. Fix the silicon nitride wafer or lithium niobate on the porous ceramic chuck of the polishing equipment respectively, perform chemical mechanical polishing to obtain a smooth surface, and then perform semiconductor RCA cleaning on both wafers to obtain a clean surface. Among them, the lithium niobate wafer is a lithium niobate wafer that has been blackened.

[0120] 2. The lithium niobate wafer processed in step 1 is implanted with oxygen ions using a stripping ion implantation method, so that the lithium niobate wafer is sequentially divided into a residual layer, a separation layer, and a thin film layer starting from the implantation surface. The implanted oxygen ions are distributed in the separation layer to obtain a single crystal lithium niobate wafer implantation sheet.

[0121] When oxygen ions are implanted by stripping ion implantation, the implantation dose parameters are: the implantation dose is 2×10 16 ions / cm 2 , the injection energy is 50keV.

[0122] 3. A polysilicon layer is formed on the cleaned silicon nitride wafer using the LPCVD method, and then chemically mechanically polished to a thickness of 1 μm.

[0123] 4. A silicon dioxide layer was made on the polysilicon layer by thermal oxidation, and then chemical mechanical polishing was performed to obtain a smooth surface with a thickness of 1 μm, and RCA cleaning was performed to obtain a clean surface.

[0124] 5. The thin film layer of the single crystal lithium niobate wafer implant is brought into contact with the silicon dioxide layer and bonded using a direct bonding method to obtain a bonded body.

[0125] 6. Under an argon atmosphere, place the bonded body in an annealing furnace and keep it at 200°C for 2 hours. The bonded body is broken and separated at the separation layer to obtain a single crystal piezoelectric composite film.

[0126] 7. Perform plasma etching on the thin film layer in the single crystal piezoelectric composite film, wherein the plasma used in the plasma etching treatment includes argon ions, and the etching condition parameters are: under vacuum conditions, etching pressure 1 Pa, etching bias 500 V, and etching at 600°C for 5 minutes.

[0127] 8. Fix the above-mentioned single crystal piezoelectric composite film on the porous ceramic chuck of the polishing equipment, perform chemical mechanical polishing on the blackened film layer until the hydrogen ions on the surface of the film layer are removed, and then perform RCA cleaning to obtain a clean surface.

[0128] The obtained blackened single crystal piezoelectric composite film sequentially comprises a blackened single crystal film layer, a silicon dioxide layer, a polysilicon layer and a silicon nitride layer.

[0129] Example 4

[0130] Example 4 provides a method for preparing a blackened single-crystal piezoelectric composite film based on plasma etching, comprising the following steps:

[0131] 1. Prepare a 300μm silicon wafer and a 400μm lithium tantalate wafer, fix the silicon wafer or lithium tantalate on the porous ceramic chuck of the polishing equipment, perform chemical mechanical polishing to obtain a smooth surface, and then perform semiconductor RCA cleaning on both wafers to obtain a clean surface; among them, the lithium tantalate wafer is a lithium tantalate wafer that has been blackened.

[0132] 2. The lithium tantalate wafer processed in step 1 is injected with argon ions by using the stripping ion implantation method, so that the lithium tantalate wafer is divided into a residual layer, a separation layer and a thin film layer in sequence starting from the implantation surface. The injected argon ions are distributed in the separation layer to obtain a single crystal lithium tantalate wafer implantation sheet.

[0133] When the stripping ion implantation method is used to implant argon ions, the implantation dose parameters are: the implantation dose is 2×10 16 ions / cm 2 , the injection energy is 50keV.

[0134] 3. Amorphous silicon with a thickness of 500 nm is produced on the cleaned silicon wafer using the PVD method.

[0135] 4. A silicon dioxide layer with a thickness of 5 μm was formed on the amorphous silicon layer by PECVD, and then chemical mechanical polishing was performed to obtain a smooth surface, and RCA cleaning was performed to obtain a clean surface.

[0136] 5. The thin film layer of the single crystal lithium tantalate wafer implant is brought into contact with the silicon dioxide layer and bonded using a direct bonding method to obtain a bonded body.

[0137] 6. Under a helium atmosphere, place the bonded body in an annealing furnace and keep it at 220°C for 3 hours. The bonded body is broken and separated at the separation layer to obtain a single crystal piezoelectric composite film.

[0138] 7. Perform plasma etching on the thin film layer in the single crystal piezoelectric composite film, wherein the plasma used in the plasma etching treatment includes neon ions, and the etching condition parameters are: under vacuum conditions, etching pressure 10 Pa, etching bias 100 V, and etching at 400°C for 16 hours.

[0139] 8. Fix the above-mentioned single crystal piezoelectric composite film on the porous ceramic chuck of the polishing equipment, perform chemical mechanical polishing on the blackened film layer until the hydrogen ions on the surface of the film layer are removed, and then perform RCA cleaning to obtain a clean surface.

[0140] The obtained blackened single crystal piezoelectric composite film sequentially comprises a blackened single crystal film layer, a silicon dioxide layer, a polycrystalline silicon layer and a single crystal silicon layer.

[0141] Example 5

[0142] Example 5 provides a method for preparing a blackened single-crystal piezoelectric composite film based on plasma etching, comprising the following steps:

[0143] 1. Prepare a 410μm silicon carbide wafer and a 300μm lithium niobate wafer. Fix the silicon carbide wafer or lithium niobate on the porous ceramic chuck of the polishing equipment respectively, perform chemical mechanical polishing to obtain a smooth surface, and then perform semiconductor RCA cleaning on both wafers to obtain a clean surface. Among them, the lithium niobate wafer is a lithium niobate wafer that has been blackened.

[0144] 2. The lithium niobate wafer processed in step 1 is implanted with helium ions using a stripping ion implantation method, so that the lithium niobate wafer is sequentially divided into a residual layer, a separation layer, and a thin film layer starting from the implantation surface. The implanted oxygen ions are distributed in the separation layer to obtain a single crystal lithium niobate wafer implantation sheet.

[0145] When the helium ion is implanted by the stripping ion implantation method, the implantation dose parameters are: the implantation dose is 2×10 16 ions / cm2 , the injection energy is 50keV.

[0146] 3. Argon ions are implanted into the cleaned silicon carbide wafer using an ion implantation method to produce a damaged layer of single crystal silicon with a thickness of 5 μm.

[0147] 4. A silicon dioxide layer was prepared on the polysilicon layer by PECVD, and then chemical mechanical polishing was performed to obtain a smooth surface with a thickness of 500 nm. RCA cleaning was performed to obtain a clean surface.

[0148] 5. The thin film layer of the single crystal lithium niobate wafer implant is brought into contact with the silicon dioxide layer and bonded using a direct bonding method to obtain a bonded body.

[0149] 6. Under nitrogen atmosphere, place the bonded body in an annealing furnace and keep it at 240°C for 2 hours. The bonded body is broken and separated at the separation layer to obtain a single crystal piezoelectric composite film.

[0150] 7. Perform plasma etching on the thin film layer in the single crystal piezoelectric composite film, wherein the plasma used for the plasma etching treatment includes argon ions and neon ions, and the etching condition parameters are: under vacuum conditions, etching pressure 2 Pa, etching bias 500 V, and etching at 200°C for 0.5 hours.

[0151] 8. Fix the above-mentioned single crystal piezoelectric composite film on the porous ceramic chuck of the polishing equipment, perform chemical mechanical polishing on the blackened film layer until the hydrogen ions on the surface of the film layer are removed, and then perform RCA cleaning to obtain a clean surface.

[0152] The obtained blackened single crystal piezoelectric composite film sequentially comprises a blackened single crystal film layer, a silicon dioxide layer, a polycrystalline silicon layer and a single crystal silicon layer.

[0153] The same and similar parts between the various embodiments in this specification can be referred to each other, especially the embodiment part corresponding to the blackened single crystal piezoelectric composite film based on plasma etching can refer to the preparation method part of the blackened single crystal piezoelectric composite film based on plasma etching.

[0154] The present application has been described in detail above with reference to specific embodiments and exemplary examples. However, these descriptions should not be construed as limiting the present application. Those skilled in the art will appreciate that, without departing from the spirit and scope of the present application, various equivalent substitutions, modifications, or improvements may be made to the technical solutions and implementations of the present application, all of which fall within the scope of the present application. The scope of protection of the present application shall be determined by the appended claims.

Claims

1. A method for preparing a blackened single crystal piezoelectric composite film based on plasma etching, characterized in that: include: Preparing a piezoelectric wafer and a substrate, wherein the piezoelectric wafer is a lithium niobate wafer or a lithium tantalate wafer; A single-crystal piezoelectric composite film is prepared by an ion implantation-bonding method or a bonding-thinning method, wherein the single-crystal piezoelectric composite film comprises a substrate and a thin film layer of a target thickness stacked in sequence; The thin film layer in the single crystal piezoelectric composite film is subjected to plasma etching treatment to blacken the thin film layer, and the blackened thin film layer is ground and polished to obtain a blackened single crystal piezoelectric composite film, wherein the plasma used in the plasma etching treatment includes reducing plasma and / or inert plasma.

2. The preparation method according to claim 1, characterized in that The single crystal piezoelectric composite film is prepared by ion implantation-bonding method, including: Implanting ions into the piezoelectric wafer by an ion implantation method to sequentially divide the piezoelectric wafer into a residual layer, a separation layer, and a thin film layer; Bonding the piezoelectric wafer to the substrate to obtain a bonded body; The bonded body is heat-treated to separate the residual material layer from the thin film layer, thereby obtaining a single crystal piezoelectric composite thin film.

3. The preparation method according to claim 1, characterized in that The single crystal piezoelectric composite film is prepared by a bonding-thinning method, including: Bonding the piezoelectric wafer and the substrate to obtain a bonded body; heat-treating the bonded body to obtain a single crystal piezoelectric composite thin film prefabricated body; The piezoelectric wafer in the single crystal piezoelectric composite thin film prefabrication is thinned to form a thin film layer of target thickness on the substrate.

4. The preparation method according to claim 1, characterized in that The method comprises performing plasma etching on the surface of the thin film layer in the single crystal piezoelectric composite thin film by a plasma etching method, comprising: In the reaction chamber, the reaction gas is ionized under the excitation of the radio frequency power source and forms a plasma, wherein the plasma includes reducing plasma and / or inert plasma; The plasma etches the thin film layer to increase the oxygen vacancy concentration in the thin film layer, wherein the temperature in the reaction chamber is 0-600° C. and the etching time is 5 minutes to 20 hours.

5. The preparation method according to claim 4, characterized in that The gas pressure in the reaction chamber is 1Pa-100Pa, and the etching bias voltage is 100-5000V.

6. The preparation method according to claim 1, characterized in that The reducing plasma includes at least one of hydrogen ions, carbon ions, and reducing metal ions.

7. The preparation method according to claim 4, characterized in that If the reducing plasma includes hydrogen ions, the reaction gas selected for the plasma etching process is hydrogen; if the reducing plasma includes carbon ions, the reaction gas selected for the plasma etching process is methane.

8. The preparation method according to claim 1, characterized in that The inert plasma includes at least one of neon ions and argon ions.

9. The preparation method according to claim 1, characterized in that The substrate is a single-layer substrate or a composite substrate.

10. A blackened single crystal piezoelectric composite film, characterized in that: The blackened single crystal piezoelectric composite film is prepared by the method for preparing a blackened single crystal piezoelectric composite film based on plasma etching according to any one of claims 1 to 9.

Images