A blackened single-crystal piezoelectric composite thin film and a preparation method thereof

Abstract

The present application discloses a blackened single-crystal piezoelectric composite film and a preparation method thereof, including: injecting ions into a first wafer by an ion implantation method, bonding the first wafer to a substrate to obtain a bonded body; performing heat treatment on the bonded body to obtain a single-crystal piezoelectric composite film; laying a second wafer or a reducing paper on the film layer of the single-crystal piezoelectric composite film to obtain a pre-preparation body; burying the pre-preparation body in blackening powder; performing blackening reduction heat treatment on the single-crystal piezoelectric composite film buried in the blackening powder in a reduction furnace; removing the second wafer or the reducing paper to obtain a blackened single-crystal piezoelectric composite film. By performing blackening reduction heat treatment on the single-crystal piezoelectric composite film after heat treatment, it can be ensured that the blackened film layer in the finally prepared blackened single-crystal piezoelectric composite film has a low pyroelectric coefficient and resistivity.

Description

Technical Field

[0001] This application belongs to the technical field of semiconductor preparation, and particularly relates to a blackened single-crystal piezoelectric composite film 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, and optoelectronic sensors due to their excellent optical properties such as piezoelectricity, ferroelectricity, optoelectronic, photoelastic, pyroelectric, photorefractive, and nonlinear optical properties.

[0003] Since both lithium niobate and lithium tantalate crystals are ferroelectric crystals, they have relatively high pyroelectric coefficients and resistivity. Thus, when preparing electronic components using lithium niobate and lithium tantalate wafers, a large amount of static charges are likely to accumulate on the surfaces of the lithium niobate and lithium tantalate wafers, and the release of these static charges will damage the lithium niobate and lithium tantalate wafers, thereby affecting the performance and yield of the prepared electronic components.

[0004] To solve the above problems, in one implementation, the lithium niobate and lithium tantalate wafers are pre-treated by blackening, where the blackening treatment refers to treating the lithium niobate and lithium tantalate wafers by 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 dark brown color; further, using the blackened lithium niobate and lithium tantalate wafers to prepare electronic components can solve the problem that the release of static charges will damage the lithium niobate or lithium tantalate wafers.

[0005] However, the applicant has found that for electronic components using piezoelectric composite films, although the pre-blackened lithium niobate and lithium tantalate wafers are used, when the prepared piezoelectric composite film is applied to electronic components, there is still a phenomenon that the release of static charges damages the electronic components. Summary of the Invention

[0006] To solve the above technical problems in the prior art, this application provides a blackened single-crystal piezoelectric composite film and a preparation method thereof.

[0007] In a first aspect, this application provides a preparation method of a blackened single-crystal piezoelectric composite film, including:

[0008] Prepare a first wafer and a substrate, where the first wafer is a lithium niobate wafer or a lithium tantalate wafer;

[0009] Inject ions into the first wafer by ion implantation to divide the first wafer into a residual layer, a separation layer, and a thin film layer in sequence;

[0010] Bond the first wafer and the substrate to obtain a bonded body;

[0011] Heat-treat the bonded body to separate the residual layer from the thin film layer, obtaining a single-crystal piezoelectric composite thin film;

[0012] Lay a second wafer or a reducing paper on the thin film layer of the single-crystal piezoelectric composite thin film to obtain a pre-preparation body;

[0013] Bury the pre-preparation body in blackening powder, where the blackening powder includes reducing powder and lithium carbonate powder;

[0014] In a reduction furnace, perform blackening reduction heat treatment on the single-crystal piezoelectric composite thin film buried in the blackening powder;

[0015] Remove the second wafer or the reducing paper to obtain a blackened single-crystal piezoelectric composite thin film.

[0016] In one feasible implementation, the second wafer and the first wafer are made of the same material.

[0017] In one feasible implementation, by mass, the blackening powder includes 1-10 parts of reducing powder and 90-99 parts of lithium carbonate powder.

[0018] In one feasible implementation, by mass, the blackening powder includes 5-10 parts of reducing powder and 90-95 parts of lithium carbonate powder.

[0019] In one feasible implementation, the reducing powder includes any one or more of iron powder, aluminum powder, zinc powder, magnesium powder, silicon powder, and carbon powder.

[0020] In one feasible implementation, the reducing powder includes a mixed powder of any one or more of iron powder, aluminum powder, zinc powder, magnesium powder, silicon powder, and carbon powder and graphene.

[0021] In one feasible implementation, in the reduction furnace, the temperature for performing blackening reduction heat treatment on the single-crystal piezoelectric composite thin film buried in the blackening powder is 300-600 °C, and the heat preservation time is 1-100 hours.

[0022] In one feasible implementation, the ions implanted into the first wafer by the ion implantation method are helium ions, hydrogen ions, nitrogen ions, oxygen ions, or argon ions, and the implantation dose is 2×10 16 ions / cm 2 -4×10 16 ions / cm 2 ; the implantation energy is 40-400 keV.

[0023] In one feasible implementation, the preparation method further includes: polishing and cleaning the surface of the thin film layer in the blackened single-crystal piezoelectric composite thin film.

[0024] In one realizable manner, the substrate is a single-layer substrate or a composite substrate.

[0025] In a second aspect, the present application provides a blackened single-crystal piezoelectric composite film, which is prepared by the preparation method of the blackened single-crystal piezoelectric composite film according to any one of the first aspect.

[0026] In a third aspect, the present application further provides an electronic component, and the electronic component includes the blackened single-crystal piezoelectric composite film of the second aspect.

[0027] For the blackened single-crystal piezoelectric composite film and its preparation method provided by the present application, after the single-crystal piezoelectric composite film is heat-treated, a blackening reduction heat treatment is performed. In this way, for the film layer prepared from the first wafer after blackening reduction, the film layer can be repaired by blackening reduction heat treatment; for the film layer prepared from the first wafer without blackening reduction, whitening of the film layer can be inhibited, so as to ensure that the blackened film layer in the finally prepared blackened single-crystal piezoelectric composite film has a low pyroelectric coefficient and resistivity. Description of the Drawings

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0029] Figure 1 It is a flowchart of a preparation method of a blackened single-crystal piezoelectric composite film provided by an embodiment of the present application.

[0030] Description of the Reference Numerals

[0031] 100 - First wafer, 110 - Residual layer, 120 - Separation layer, 130 - Film layer, 130A - Blackened film layer, 200 - Substrate, 300 - Bonding body, 400 - Second wafer, 500 - Blackening powder. Detailed Embodiments

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application.

[0033] As introduced in the background art section, to solve the technical problem that a large amount of static charges are easily accumulated on the surfaces 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.

[0034] However, the applicant found that when the above piezoelectric composite film is applied to electronic components, there is still a phenomenon that the release of static charges damages the electronic components. Based on this, the applicant further studied and analyzed and found that: during the preparation of the piezoelectric composite film, after the lithium niobate or lithium tantalate thin film layer is separated from the remaining layer, the bonded body of the thin film layer and the substrate wafer is annealed at a high temperature to further enhance the bonding force and eliminate the lattice defects formed in the thin film layer during the ion implantation process. However, the applicant found that during the high-temperature annealing process, there is a phenomenon that the thin film layer that should originally be brownish has partial or complete whitening, that is to say, the originally blackened thin film layer in the finally prepared composite film material resumes the characteristics of having a relatively high pyroelectric coefficient and resistivity, thereby affecting the performance of the electronic components to which it is applied.

[0035] Based on the above analysis, the 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 by using the blackened lithium niobate or lithium tantalate wafer still has the phenomenon that the release of static charges damages the electronic components.

[0036] The following will detail a method for preparing a blackened single-crystal piezoelectric composite film provided by the embodiment of the present application.

[0037] As Figure 1 shown, a method for preparing a blackened single-crystal piezoelectric composite film provided by the embodiment of the present application includes the following steps:

[0038] Step 100, prepare a first wafer 100 and a substrate 200, wherein the first wafer 100 is a lithium niobate wafer or a lithium tantalate wafer.

[0039] In the embodiment of the present application, the first wafer 100 refers to a basic material with a certain thickness for preparing a thin film layer. Among them, the first wafer can be an unblackened wafer or a blackened wafer, and the present application does not limit this. If the first wafer is a blackened wafer, the first wafer 100 can be obtained by direct purchase; or, the first wafer 100 can be a lithium niobate wafer or a lithium tantalate wafer that is not blackened and directly purchased, and is blackened. Among them, the blackening method for the lithium niobate wafer or the lithium tantalate wafer can adopt any existing feasible blackening method, and the present application does not limit this.

[0040] In the embodiments of the present application, the substrate 200 may be a single-layer substrate or a composite substrate, that is, the substrate 200 includes at least one substrate layer. The materials of each substrate layer may be the same or different, and the present application does not limit this. For example, the substrate layer material may be lithium niobate, lithium tantalate, quartz, silicon, sapphire, SOI, diamond, silicon carbide, silicon nitride, gallium arsenide, indium phosphide, etc., and the present application does not limit this.

[0041] Step 200: Inject ions into the first wafer 100 by ion implantation method, and the first wafer 100 is successively divided into a residual layer 110, a separation layer 120, and a thin film layer 130.

[0042] The embodiments of the present application do not particularly limit the ion implantation method, and 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 injecting ions, the injection dose can be 2×10 16 ions / cm 2 ~4×10 16 ions / cm 2 , and the injection energy can be 40 keV to 400 keV. For example, the injection energy is 50 keV.

[0043] In the embodiments 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 ion implantation depth, the greater the thickness of the prepared thin film layer 130; on the contrary, the smaller the ion implantation depth, the smaller the thickness of the prepared thin film layer 130.

[0044] Step 300: Bond the first wafer 100 to the substrate 200 to obtain a bonded body 300.

[0045] After bonding, the thin film layer 130 of the first wafer 100 contacts the substrate 200 and is stacked on the substrate 200. In this way, the bonded body 300 is successively stacked with a residual layer 110, a separation layer 120, a thin film layer 130, and a substrate 200 from top to bottom.

[0046] The present application does not particularly limit the bonding method, and any bonding method in the prior art can be adopted. For example, bonding is carried out by means of surface activation to obtain a bonded body. The present application does not limit the surface activation method either. For example, methods such as plasma activation or chemical solution activation can be adopted.

[0047] It should be noted that before step 300, the present application may further include a step of preparing an isolation layer on the substrate 200. For example, if the substrate 200 is a single-layer silicon substrate, silicon oxide can be prepared on the single-layer silicon substrate by thermal oxidation, and the generated silicon oxide layer serves as the isolation layer. In this way, in step 300, the first wafer 100 is bonded to the substrate 200 with the isolation layer to obtain a bonded body.

[0048] It should also be noted that the isolation layer prepared on the substrate 200 can be single-layer or multi-layer, and the present application does not limit this. For example, an alternating stack of silicon oxide layers and silicon nitride layers is prepared on the substrate 200.

[0049] Step 400: Heat-treat the bonded body 300 to separate the residual layer 110 from the thin film layer 130 to obtain a single-crystal piezoelectric composite thin film.

[0050] The bonded body 300 is heat-treated. The heat treatment process can be carried out 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 gas, He ions form helium gas, etc. As the heat treatment progresses, the bubbles in the separation layer 120 are connected into a continuous sheet, and finally the separation layer 120 cracks, separating the residual layer 110 from the thin film layer 130, so that the residual layer 110 is peeled off from the bonded body 300 to obtain a single-crystal piezoelectric composite thin film. Among them, the single-crystal piezoelectric composite thin film is stacked with the thin film layer 130 and the substrate 200 in sequence from top to bottom.

[0051] When the first wafer is a blackened lithium niobate wafer or lithium tantalate wafer, after the above step 400, the applicant found that there is a phenomenon of partial or complete whitening in the thin film layer 130 that should originally be brown in the single-crystal piezoelectric composite thin film. It can be seen that after heat-treating the bonded body, the originally blackened thin film layer 130 is partially or completely oxidized. To change this phenomenon, the following steps 500 to 800 are performed.

[0052] It should be noted that when the first wafer is a non-blackened lithium niobate wafer or lithium tantalate wafer, the following steps 500 to 800 are also performed to blacken the thin film layer 130, so that it can be ensured that the thin film layer 130 in the finally prepared blackened single-crystal piezoelectric composite thin film is in a completely blackened state.

[0053] Step 500: Lay the second wafer 400 or a reducing paper (not shown in the figure) on the thin film layer 130 of the single-crystal piezoelectric composite thin film to obtain a pre-preparation body.

[0054] First, it should be noted that the material of the second wafer 400 is not limited in this application. However, to avoid introducing other unnecessary impurities into the thin film layer 130, the second wafer 400 is preferably a wafer made of the same material as the first wafer 100.

[0055] Among them, the second wafer 400 and the reducing paper can, on the one hand, remove static electricity, and on the other hand, isolate the thin film layer 130 from the blackening powder. In this way, when the preform is buried in the blackening powder, no particulate impurities will adhere to the surface of the thin film layer 130, thus ensuring the cleanliness of the thin film layer 130.

[0056] In addition, relative to the second wafer 400, the reducing paper can also be a source of reducing material, and the reducing paper can be tin foil paper.

[0057] Step 600: Burry the preform in the blackening powder 500, where the blackening powder 500 includes reducing powder and lithium carbonate powder.

[0058] Step 700: In a reduction furnace, perform blackening reduction heat treatment on the single crystal piezoelectric composite thin film buried in the blackening powder.

[0059] Step 800: Remove the second wafer or the reducing paper to obtain a blackened single crystal piezoelectric composite thin film.

[0060] After the above-mentioned embodiments obtain the blackened single crystal piezoelectric composite thin film, it may further include steps of polishing and cleaning the surface of the thin film layer in the blackened single crystal piezoelectric composite thin film, so that the surface roughness of the blackened single crystal piezoelectric composite thin film meets the requirements.

[0061] In this application, the blackening powder 500 will react in the reduction furnace to generate reducing gas carbon monoxide, and then the thin film layer in the preform is subjected to blackening reduction heat treatment through carbon monoxide, thereby repairing the blackening of the thin film layer or suppressing the whitening of the thin film layer. Specifically, the reducing gas carbon monoxide can react with the oxygen in the thin film layer to increase the oxygen vacancy concentration in the thin film layer, thereby reducing the resistivity and repairing the blackening of the thin film layer or suppressing the whitening of the thin film layer.

[0062] In addition, it should be noted that if the blackening powder 500 is directly contacted with the surface of the thin film layer in the preform for blackening reduction heat treatment, the blackening powder 500 will damage the thin film layer. Then, after the blackening reduction is completed, it is necessary to polish and remove a thickness of several micrometers to dozens of micrometers on the surface of the thin film layer to remove the damaged layer on the surface of the thin film layer, which is unacceptable for the thin film. Therefore, compared with the method of directly contacting the blackening powder 500 with the surface of the thin film layer in the preform for blackening reduction heat treatment, in this application, by laying the second wafer 400 or the reducing paper on the thin film layer in the preform, the surface of the thin film layer after blackening reduction can be prevented from being damaged.

[0063] It should also be noted that although a second wafer or a reducing paper is laid on the thin film layer of the single crystal piezoelectric composite film in this application, the reducing gas carbon monoxide generated in the reduction furnace can diffuse to the surface of the thin film layer of the single crystal piezoelectric composite film and react with it, while the blackening powder will not contact the surface of the thin film layer of the single crystal piezoelectric composite film.

[0064] This application does not limit the material of the reducing powder in the blackening powder 500. For example, the reducing powder can be any one or a mixture of iron powder, aluminum powder, zinc powder, magnesium powder, silicon powder, and carbon powder. Among them, the carbon powder can be all powders containing carbon elements, such as diamond, C60, C70, graphite powder, activated carbon, carbon black, charcoal, etc.; the silicon powder can be silicon elemental powder. For another example, the reducing powder can also be a mixed powder of any one or more of iron powder, aluminum powder, zinc powder, magnesium powder, silicon powder, and carbon powder and graphene. In this way, the graphene in the mixed powder can greatly enhance the reducibility of the reducing powder.

[0065] Before use, the reducing powder in the blackening powder 500 and lithium carbonate powder are weighed according to a preset ratio, and then mechanically ground and evenly mixed to be used as a composite reducing agent for the blackening reduction reaction of the single crystal piezoelectric composite film. Among them, the lithium carbonate powder can also play a role in improving the uniformity of reduction.

[0066] The blackening reduction heat treatment process for the single crystal piezoelectric composite film can be to keep the temperature at 300 - 600 °C for 1 - 100 hours, and more preferably, the blackening reduction of the thin film layer can be completed by keeping the temperature at 500 - 600 °C for 2 - 4 hours. The blackened single crystal piezoelectric composite film includes a blackened thin film layer 130A and a substrate 200.

[0067] In summary, in this application, the single crystal piezoelectric composite film after heat treatment is further subjected to blackening reduction heat treatment. In this way, for the thin film layer prepared from the first wafer after blackening reduction, the blackening reduction heat treatment can be carried out for repair; for the thin film layer prepared from the first wafer without blackening reduction, the whitening of the thin film layer can be inhibited, so as to ensure that the blackened thin film layer in the finally prepared blackened single crystal piezoelectric composite film has a lower pyroelectric coefficient and resistivity. In addition, laying the second wafer 400 or the reducing paper on the thin film layer in the pre-prepared body can also prevent the surface of the thin film layer after blackening reduction from being damaged.

[0068] The applicant has found that the ratio of the reducing powder to the lithium carbonate powder in the blackening powder has a certain influence on the blackening reduction effect of the thin film layer in the preform. Through research and comparison, it is found that when the blackening powder adopts the following ratio, the blackening reduction effect of the prepared blackening single crystal piezoelectric composite film is the best. In this ratio, by mass, it includes 5-10 parts of reducing powder and 90-95 parts of lithium carbonate powder. When the addition amount of the reducing powder is less than 5 parts, it is not enough to completely blacken the thin film layer; when the addition amount of the reducing powder is greater than 10 parts, due to the too fast rate of carbon monoxide generation, part of the carbon monoxide has no time to reduce and blacken the thin film layer, resulting in waste of carbon monoxide; when the blackening powder includes 5-10 parts of reducing powder and 90-95 parts of lithium carbonate powder, it can already completely blacken the thin film layer without wasting excess carbon monoxide.

[0069] The following uses experimental data to illustrate the effect of the blackening single crystal piezoelectric composite film prepared by the blackening reduction heat treatment of the preform buried with the blackening powder in this application.

[0070] Experimental Example 1

[0071] The blackening single crystal piezoelectric composite film was prepared by the above method provided in the embodiment of the present application. Among them, the first wafer uses a lithium tantalate wafer with a thickness of 0.25 mm, and the substrate uses a silicon wafer with a thickness of 0.25 mm; the reduction paper (i.e., aluminum foil paper) is laid on the thin film layer of the single crystal piezoelectric composite film. The blackening powder is iron powder and lithium carbonate powder, and the mass ratio of iron powder to lithium carbonate powder is 5:95; in the reduction furnace, the temperature for the blackening reduction heat treatment of the single crystal piezoelectric composite film buried in the blackening powder is 530 °C, and the heat preservation time is 4 hours.

[0072] Experimental Example 2

[0073] Experimental Example 2 is basically the same as the above Experimental Example 1, except that in Experimental Example 2, the mass ratio of iron powder to lithium carbonate powder is 10:90.

[0074] Experimental Example 3

[0075] Experimental Example 3 is basically the same as the above Experimental Example 1, except that in Experimental Example 3, the mass ratio of iron powder to lithium carbonate powder is 1:99.

[0076] Experimental Example 4

[0077] Experimental Example 4 is basically the same as the above Experimental Example 1, except that in Experimental Example 4, a lithium tantalate wafer is laid on the thin film layer of the single crystal piezoelectric composite film, and the blackening powder is iron powder and lithium carbonate powder, and the mass ratio of iron powder to lithium carbonate powder is 5:95.

[0078] Experimental Example 5

[0079] Experimental Example Five is basically the same as Experimental Example Four above, except that in Experimental Example Five, the mass ratio of iron powder to lithium carbonate powder is 10:90.

[0080] Experimental Example Six

[0081] Experimental Example Six is basically the same as Experimental Example Four above, except that in Experimental Example Six, the mass ratio of iron powder to lithium carbonate powder is 1:99.

[0082] Experimental Example Seven

[0083] The above method provided in the embodiment of the present application is used to prepare a blackened single-crystal piezoelectric composite film. Among them, the first wafer uses a lithium niobate wafer with a thickness of 0.25 mm, and the substrate uses a silicon wafer with a thickness of 0.25 mm; a lithium niobate wafer is laid on the film layer of the single-crystal piezoelectric composite film, and the blackening powder is iron powder and lithium carbonate powder, where the mass ratio of iron powder to lithium carbonate powder is 5:95; in the reduction furnace, the temperature for blackening and reducing heat treatment of the single-crystal piezoelectric composite film buried in the blackening powder is 530 °C, and the heat preservation time is 4 hours.

[0084] Experimental Example Eight

[0085] Experimental Example Eight is basically the same as Experimental Example Seven above, except that in Experimental Example Eight, the mass ratio of iron powder to lithium carbonate powder is 10:90.

[0086] Experimental Example Nine

[0087] Experimental Example Nine is basically the same as Experimental Example Seven above, except that in Experimental Example Nine, the mass ratio of iron powder to lithium carbonate powder is 1:99.

[0088] Comparative Example One

[0089] Comparative Example One is basically the same as Experimental Example One, except that in Comparative Example One, the prepared preform is directly placed in the reduction furnace, and carbon monoxide gas is introduced for blackening and reducing heat treatment. Among them, the preform is neither laid with reduction paper nor buried in the blackening powder.

[0090] Comparative Example Two

[0091] Comparative Example Two is basically the same as Experimental Example One, except that in Comparative Example Two, the preform laid with reduction paper is directly placed in the reduction furnace, and carbon monoxide gas is introduced for blackening and reducing heat treatment. Among them, the preform is not buried in the blackening powder.

[0092] Comparative Example Three

[0093] Comparative Example 3 is basically the same as Experimental Example 4, except that in Comparative Example 3, the pre-prepared body paved with a lithium tantalate wafer is directly placed in a reduction furnace, and carbon monoxide gas is introduced for blackening reduction heat treatment. Among them, the pre-prepared body is not buried in the blackening powder.

[0094] Comparative Example 4

[0095] Comparative Example 4 is basically the same as Experimental Example 7, except that in Comparative Example 4, the pre-prepared body paved with a lithium niobate wafer is directly placed in a reduction furnace, and carbon monoxide gas is introduced for blackening reduction heat treatment. Among them, the pre-prepared body is not buried in the blackening powder.

[0096] The properties of the blackened single-crystal piezoelectric composite films prepared in the above experimental examples and comparative examples were tested, including observing the appearance color of the film layer in the blackened single-crystal piezoelectric composite film and the resistivity of the film layer in the blackened single-crystal piezoelectric composite film. See Table 1 below for details.

[0097] Table 1 Comparison results of the properties of the blackened single-crystal piezoelectric composite films prepared in experimental examples and comparative examples

[0098]

[0099] The present application also provides a blackened single-crystal piezoelectric composite film, which is obtained by using the preparation method provided in the above embodiments.

[0100] In one implementable manner, the present application provides a blackened single-crystal piezoelectric composite film, including a blackened film layer and a substrate stacked in sequence. Among them, the substrate can be a single-layer substrate or a composite substrate.

[0101] In another implementable manner, 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 substrate.

[0102] The present application also provides an electronic component, which uses the blackened single-crystal piezoelectric composite film provided in the embodiments of the present application. The film layer in the blackened single-crystal piezoelectric composite film provided in the embodiments of the present application is repaired by blackening reduction heat treatment, which can effectively reduce the pyroelectric effect of the single-crystal piezoelectric composite film. Therefore, it will not affect the use performance of the electronic component during use.

[0103] The preparation method provided by the present application is described below through specific examples.

[0104] Example 1

[0105] A preparation method of a blackened single-crystal piezoelectric composite film provided in Example 1 includes the following steps:

[0106] 1. Prepare a 200-μm silicon wafer and a 200-μm lithium tantalate wafer. Fix the silicon wafer or lithium tantalate on the porous ceramic chuck of the polishing equipment respectively, and perform chemical mechanical polishing to obtain a smooth surface. Then, perform semiconductor RCA cleaning on the two wafers to obtain a clean surface; among them, the lithium tantalate wafer is a lithium tantalate wafer after blackening treatment.

[0107] 2. Inject He into the lithium tantalate wafer processed in step 1 by the stripping ion implantation method + , so that the lithium tantalate wafer is successively divided into a residual layer, a separation layer and a thin film layer starting from the injection surface. The injected He + is distributed in the separation layer to obtain a single-crystal lithium tantalate wafer injection sheet.

[0108] When injecting He by the stripping ion implantation method + , the injection dose parameters are: the injection dose is 2×10 16 ions / cm 2 , the injection energy is 40 keV, and the injection depth is 220 nm.

[0109] 3. Fabricate a silicon dioxide layer on the cleaned silicon wafer by LPCVD method, and then perform chemical mechanical polishing to a thickness of 100 nm to obtain a smooth surface, and perform RCA cleaning to obtain a clean surface.

[0110] 4. Contact the thin film layer of the single-crystal lithium tantalate wafer injection sheet with the silicon dioxide layer, and bond them by direct bonding method to obtain a bonded body.

[0111] 5. Under a nitrogen atmosphere, put the bonded body into an annealing furnace and keep it at 180 °C for 2 hours. The bonded body disconnects and separates at the separation layer to obtain a single-crystal piezoelectric composite film.

[0112] 6. Lay aluminum foil paper on the thin film layer of the single-crystal piezoelectric composite film obtained in step 5, and bury the single-crystal piezoelectric composite film with aluminum foil paper laid in the blackening powder (composite powder of aluminum powder and lithium carbonate). Among them, by mass ratio, aluminum powder: lithium carbonate powder = 5:95.

[0113] 7. Under a nitrogen atmosphere, in a reduction furnace at 500 °C, keep the single-crystal piezoelectric composite film buried in the blackening powder for 4 h for blackening reduction reaction. After the blackening reduction is completed, take it out from the blackening powder and remove the laid aluminum foil paper to obtain a blackened single-crystal piezoelectric composite film.

[0114] 8. Fix the blackened single-crystal piezoelectric composite film on the porous ceramic chuck of the polishing equipment, perform chemical mechanical polishing treatment on the thin film layer until the reducing ions on the surface of the thin film layer are removed, and then perform RCA cleaning to obtain a clean surface.

[0115] The obtained blackened single-crystal piezoelectric composite film successively includes a blackened film layer, a silicon dioxide layer, and a single-crystal silicon layer. Among them, the material of the film layer is single-crystal lithium tantalate.

[0116] Example 2

[0117] A preparation method of a blackened single-crystal piezoelectric composite film provided in Example 2 includes the following steps:

[0118] 1. Prepare a 500-μm silicon carbide wafer and a 500-μm lithium tantalate wafer. Fix the silicon carbide wafer or the lithium tantalate wafer on the porous ceramic chuck of the polishing equipment respectively, and perform chemical mechanical polishing to obtain a smooth surface. Then, perform semiconductor RCA cleaning on the two wafers to obtain a clean surface. Among them, the lithium tantalate wafer is a blackened lithium tantalate wafer.

[0119] 2. Inject nitrogen ions into the lithium tantalate wafer processed in step 1 by the peel-off ion implantation method, so that the lithium tantalate wafer is successively divided into a residual layer, a separation layer, and a film layer starting from the injection surface. The injected nitrogen ions are distributed in the separation layer to obtain an injected wafer of single-crystal lithium tantalate;

[0120] When injecting nitrogen ions by the peel-off ion implantation method, the injection dose parameter is: the injection dose is 2×10 16 ions / cm 2 , and the injection energy is 50 keV.

[0121] 3. Deposit a 10-μm-thick amorphous silicon layer on the cleaned silicon carbide wafer by PVD;

[0122] 4. Deposit a silicon dioxide layer on the amorphous silicon layer by PVD, and then perform chemical mechanical polishing to obtain a smooth surface with a thickness of 10 μm, and perform RCA cleaning to obtain a clean surface.

[0123] 5. Contact the injected wafer of single-crystal lithium tantalate with the silicon dioxide layer and bond them by the direct bonding method to obtain a bonded body.

[0124] 6. Place the bonded body in an annealing furnace under a hydrogen atmosphere and keep it at 280 °C for 4 hours. The bonded body is separated at the separation layer to obtain a single-crystal piezoelectric composite film.

[0125] 7. Lay a single-crystal lithium niobate wafer on the film of the single-crystal piezoelectric composite film obtained in step 6, and bury the single-crystal piezoelectric composite film with the laid single-crystal lithium niobate wafer in blackening powder (a composite powder of iron powder and lithium carbonate). Among them, by mass ratio, iron powder: lithium carbonate powder = 8:92.

[0126] 8. Under a hydrogen atmosphere, in a reduction furnace at 550 °C, the single-crystal piezoelectric composite thin film buried in the blackening powder is heat-preserved for 4 h to carry out the blackening reduction reaction. After the blackening reduction is completed, it is taken out from the blackening powder and the laid lithium niobate single-crystal wafer is removed to obtain the blackened single-crystal piezoelectric composite thin film.

[0127] 9. Fix the blackened single-crystal piezoelectric composite thin film on the porous ceramic suction cup of the polishing equipment, carry out chemical mechanical polishing treatment on the thin film layer until the reducing ions on the surface of the thin film layer are removed, and then carry out RCA cleaning to obtain a clean surface.

[0128] The obtained blackened single-crystal piezoelectric composite thin film sequentially includes a blackened thin film layer, a silicon dioxide layer, a polysilicon layer, and a silicon carbide layer. Among them, the material of the thin film layer is single-crystal lithium tantalate.

[0129] Example 3

[0130] A preparation method of a blackened single-crystal piezoelectric composite thin film provided by Example 3 includes the following steps:

[0131] 1. Prepare a 200-μm silicon nitride wafer and a 250-μm lithium niobate wafer. Fix the silicon nitride wafer or the lithium niobate wafer on the porous ceramic suction cup of the polishing equipment respectively, carry out chemical mechanical polishing treatment to obtain a smooth surface, and then carry out semiconductor RCA cleaning on the two wafers to obtain a clean surface. Among them, the lithium niobate wafer is a lithium niobate wafer after blackening treatment.

[0132] 2. Inject oxygen ions into the lithium niobate wafer processed in step 1 by the 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 from the injection surface. The injected oxygen ions are distributed in the separation layer to obtain a single-crystal lithium niobate wafer injection sheet.

[0133] When injecting oxygen ions by the stripping ion implantation method, the injection dose parameter is: the injection dose is 3×10 16 ions / cm 2 , and the injection energy is 400 keV.

[0134] 3. Fabricate a polysilicon layer on the cleaned silicon nitride wafer by PECVD method, and the thickness of the polysilicon layer is 1 μm.

[0135] 4. Fabricate a silicon dioxide layer on the polysilicon layer by thermal oxidation method, and then carry out chemical mechanical polishing to obtain a smooth surface, with a thickness of 1 μm, and RCA cleaning to obtain a clean surface.

[0136] 5. Contact the single-crystal lithium niobate wafer injection sheet with the silicon dioxide layer and bond them by the direct bonding method to obtain a bonded body.

[0137] 6. Under an argon atmosphere, place the bonded body in an annealing furnace, hold it at 200 °C for 2 hours, and the bonded body separates at the separation layer to obtain a single-crystal piezoelectric composite film.

[0138] 7. Lay aluminum foil paper on the film layer of the single-crystal piezoelectric composite film obtained after the treatment in step 6, and bury the single-crystal piezoelectric composite film with the aluminum foil paper laid thereon in blackening powder (a composite powder of zinc powder and lithium carbonate). Among them, by mass ratio, zinc powder: lithium carbonate powder = 10:90.

[0139] 8. Under an argon atmosphere, in a reduction furnace at 300 °C, hold the single-crystal piezoelectric composite film buried in the blackening powder for 100 h for a blackening reduction reaction. After the blackening reduction is completed, take it out from the blackening powder and remove the laid aluminum foil paper to obtain a blackened single-crystal piezoelectric composite film.

[0140] 9. Fix the blackened single-crystal piezoelectric composite film on a porous ceramic chuck of a polishing device, perform chemical mechanical polishing on the film layer until the reducing ions on the surface of the film layer are removed, and then perform RCA cleaning to obtain a clean surface.

[0141] The obtained blackened single-crystal piezoelectric composite film successively includes a blackened film layer, a silicon dioxide layer, a polysilicon layer, and a silicon nitride layer. Among them, the material of the film layer is single-crystal lithium niobate.

[0142] Example 4

[0143] A preparation method of a blackened single-crystal piezoelectric composite film provided by Example 4 includes the following steps:

[0144] 1. Prepare a 300-μm silicon wafer and a 400-μm lithium tantalate wafer, respectively fix the silicon wafer or the lithium tantalate wafer on a porous ceramic chuck of a polishing device, perform chemical mechanical polishing to obtain a smooth surface, and then perform semiconductor RCA cleaning on the two wafers to obtain a clean surface. Among them, the lithium tantalate wafer is a lithium tantalate wafer after blackening treatment.

[0145] 2. Inject argon ions into the lithium niobate wafer after the treatment in step 1 by the lift-off ion implantation method, so that the lithium niobate wafer is successively divided into a residual layer, a separation layer, and a film layer starting from the implantation surface. The implanted argon ions are distributed in the separation layer to obtain an implanted single-crystal lithium tantalate wafer.

[0146] When injecting argon ions by the lift-off ion implantation method, the injection dose parameter is: the injection dose is 4×10 16 ions / cm 2 , and the injection energy is 225 keV.

[0147] 3. Fabricate an amorphous silicon layer on the cleaned silicon wafer by PVD method, and the thickness of the amorphous silicon layer is 500 nm.

[0148] 4. Deposit a silicon dioxide layer on the amorphous silicon layer by PECVD method with a thickness of 5 μm, then perform chemical mechanical polishing to obtain a smooth surface and RCA cleaning to obtain a clean surface.

[0149] 5. Bring the single crystal lithium tantalate wafer injection sheet into contact with the silicon dioxide layer and bond them by direct bonding method to obtain a bonded body.

[0150] 6. Place the bonded body in an annealing furnace under a helium atmosphere and hold it at 220 °C for 3 hours. The bonded body separates at the separation layer to obtain a single crystal piezoelectric composite thin film.

[0151] 7. Lay a lithium tantalate single crystal wafer on the thin film of the single crystal piezoelectric composite thin film obtained after the treatment in step 6, and bury the single crystal piezoelectric composite thin film with the laid lithium tantalate single crystal wafer in a blackening powder (a composite powder of magnesium powder and lithium carbonate). Among them, by mass ratio, magnesium powder: lithium carbonate powder = 1:99.

[0152] 8. Under a helium atmosphere, in a reduction furnace at 600 °C, keep the single crystal piezoelectric composite thin film buried in the blackening powder for 1 h for blackening reduction reaction. After the blackening reduction is completed, take it out from the blackening powder and remove the laid lithium tantalate single crystal wafer to obtain a blackened single crystal piezoelectric composite thin film.

[0153] 9. Fix the blackened single crystal piezoelectric composite thin film on the porous ceramic chuck of the polishing equipment, perform chemical mechanical polishing on the thin film layer until the reducing ions on the surface of the thin film layer are removed, and then perform RCA cleaning to obtain a clean surface.

[0154] The obtained blackened single crystal piezoelectric composite thin film successively includes a blackened thin film layer, a silicon dioxide layer, a polysilicon layer and a single crystal silicon layer. Among them, the material of the thin film layer is single crystal lithium tantalate.

[0155] Example Five

[0156] A preparation method of a blackened single crystal piezoelectric composite thin film provided by Example Five includes the following steps:

[0157] 1. Prepare a 410 μm silicon carbide wafer and a 300 μm lithium niobate wafer. Fix the silicon carbide wafer or the lithium niobate wafer 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 the two wafers to obtain a clean surface. Among them, the lithium niobate wafer is a blackened lithium niobate wafer.

[0158] 2. Inject He into the lithium niobate wafer treated in step 1 by the stripping ion implantation method + , so that the lithium niobate wafer is successively divided into a residual layer, a separation layer and a thin film layer starting from the injection surface. The injected He +Ions are distributed in the separation layer to obtain an implanted wafer of single-crystalline lithium niobate.

[0159] Helium is implanted by the lift-off ion implantation method. + When doing so, the implantation dose parameters are: the implantation dose is 3×10 16 ions / cm 2 , and the implantation energy is 35 keV.

[0160] 3. Argon ions are implanted into the cleaned silicon carbide wafer by ion implantation to produce a damaged layer of single-crystalline silicon as the dielectric layer, with a thickness of 5 μm.

[0161] 4. A silicon dioxide layer is fabricated on the dielectric layer by PECVD method, and then chemical mechanical polishing is carried out to obtain a smooth surface with a thickness of 500 nm, and RCA cleaning is performed to obtain a clean surface.

[0162] 5. The implanted wafer of single-crystalline lithium niobate is brought into contact with the silicon dioxide layer and bonded by direct bonding to obtain a bonded body.

[0163] 6. In a nitrogen atmosphere, the bonded body is placed in an annealing furnace and kept at 240 °C for 2 hours. The bonded body is separated at the separation layer to obtain a single-crystalline piezoelectric composite film.

[0164] 7. A lithium niobate single-crystalline wafer is laid on the film layer of the single-crystalline piezoelectric composite film obtained after the treatment in step 6. The single-crystalline piezoelectric composite film with the laid lithium niobate single-crystalline wafer is buried in a blackening powder (a composite powder of iron powder, aluminum powder and lithium carbonate). Among them, by mass ratio, iron powder:aluminum powder:lithium carbonate powder = 5:5:90.

[0165] 8. In a nitrogen atmosphere, in a reduction furnace at 550 °C, the single-crystalline piezoelectric composite film buried in the blackening powder is kept warm for 3 h for the blackening reduction reaction. After the blackening reduction is completed, it is taken out from the blackening powder and the laid lithium tantalate single-crystalline wafer is removed to obtain a blackened single-crystalline piezoelectric composite film.

[0166] 9. The blackened single-crystalline piezoelectric composite film is fixed on the porous ceramic chuck of the polishing equipment, and the film layer is subjected to chemical mechanical polishing treatment until the reducing ions on the surface of the film layer are removed, and then RCA cleaning is carried out to obtain a clean surface.

[0167] The obtained blackened single-crystalline piezoelectric composite film successively includes a film layer, a silicon dioxide layer, a dielectric layer and a single-crystalline silicon layer; wherein the material of the film layer is single-crystalline lithium niobate.

[0168] Example Six

[0169] A preparation method of a blackened single-crystalline piezoelectric composite film provided by Example Six includes the following steps:

[0170] 1. Prepare a 300-μm silicon carbide wafer and a 300-μm lithium niobate wafer. Fix the silicon carbide wafer or the lithium niobate wafer on the porous ceramic chuck of the polishing equipment respectively, and perform chemical mechanical polishing to obtain a smooth surface. Then, perform semiconductor RCA cleaning on both wafers to obtain a clean surface. Among them, the lithium niobate wafer is the lithium niobate wafer after blackening treatment.

[0171] 2. Inject He into the lithium niobate wafer processed in step 1 by the lift-off ion implantation method + , so that the lithium niobate wafer is sequentially divided into a residue layer, a separation layer and a thin film layer starting from the implantation surface. The injected He + ions are distributed in the separation layer to obtain a single-crystal lithium niobate wafer implanted sheet.

[0172] When injecting He + by the lift-off ion implantation method, the injection dose parameters are: the injection dose is 3×10 16 ions / cm 2 , and the injection energy is 35 keV.

[0173] 3. Inject argon ions into the cleaned silicon carbide wafer by ion implantation to produce a damaged layer of single crystal silicon as the dielectric layer, and its thickness is 5 μm.

[0174] 4. Deposit a silicon dioxide layer on the dielectric layer by PECVD method, and then perform chemical mechanical polishing to obtain a smooth surface with a thickness of 500 nm, and perform RCA cleaning to obtain a clean surface.

[0175] 5. Contact the single-crystal lithium niobate wafer implanted sheet with the silicon dioxide layer and bond them by direct bonding to obtain a bonded body.

[0176] 6. In a nitrogen atmosphere, put the bonded body into an annealing furnace and keep it at 240 °C for 2 hours. The bonded body is separated at the separation layer to obtain a single-crystal piezoelectric composite film.

[0177] 7. Lay a lithium niobate single-crystal wafer on the thin film layer of the single-crystal piezoelectric composite film obtained after step 6 processing, and bury the single-crystal piezoelectric composite film with the laid lithium niobate single-crystal wafer in the blackening powder (a composite powder of silicon powder and lithium carbonate). Among them, by mass ratio, silicon powder: lithium carbonate powder = 5:95.

[0178] 8. In a nitrogen atmosphere, in a reduction furnace at 550 °C, keep the single-crystal piezoelectric composite film buried in the blackening powder for 3 h for blackening reduction reaction. After the blackening reduction is completed, take it out from the blackening powder and remove the laid lithium tantalate single-crystal wafer to obtain a blackened single-crystal piezoelectric composite film.

[0179] 9. Fix the blackened single-crystal piezoelectric composite film on the porous ceramic chuck of the polishing equipment, perform chemical mechanical polishing on the film layer until the reducing ions on the surface of the film layer are removed, and then perform RCA cleaning to obtain a clean surface.

[0180] The obtained blackened single-crystal piezoelectric composite film sequentially includes a film layer, a silicon dioxide layer, a dielectric layer, and a single-crystal silicon layer; wherein the material of the film layer is single-crystal lithium niobate.

[0181] Example Seven

[0182] A preparation method of a blackened single-crystal piezoelectric composite film provided by Example Seven includes the following steps:

[0183] 1. Prepare a 300-μm silicon carbide wafer and a 300-μm lithium tantalate wafer, respectively fix the silicon carbide wafer or the lithium tantalate wafer 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 the two wafers to obtain a clean surface, wherein the lithium tantalate wafer is a blackened lithium tantalate wafer.

[0184] 2. Inject He + into the lithium tantalate wafer processed in Step 1 by the stripping ion implantation method, so that the lithium tantalate wafer is sequentially divided into a residual layer, a separation layer, and a film layer starting from the implantation surface. The injected He + ions are distributed in the separation layer to obtain a single-crystal lithium tantalate wafer implanted sheet.

[0185] When injecting He + by the stripping ion implantation method, the injection dose parameters are: the injection dose is 3×10 16 ions / cm 2 , and the injection energy is 35 keV.

[0186] 3. Inject argon ions into the cleaned silicon carbide wafer by the ion implantation method to fabricate a damaged layer of single-crystal silicon as the dielectric layer, and its thickness is 5 μm.

[0187] 4. Fabricate a silicon dioxide layer on the dielectric layer by PECVD method, and then perform chemical mechanical polishing to obtain a smooth surface, with a thickness of 500 nm, and perform RCA cleaning to obtain a clean surface.

[0188] 5. Contact the single-crystal lithium tantalate wafer implanted sheet with the silicon dioxide layer and bond them by the direct bonding method to obtain a bonded body.

[0189] 6. Under a nitrogen atmosphere, put the bonded body into an annealing furnace, keep it at 240 °C for 2 hours, and the bonded body disconnects and separates at the separation layer to obtain a single-crystal piezoelectric composite film.

[0190] 7. Lay a lithium tantalate single crystal wafer on the film layer of the single crystal piezoelectric composite film obtained after the treatment in step 6, and bury the single crystal piezoelectric composite film with the lithium tantalate single crystal wafer laid thereon in a blackening powder (a composite powder of diamond powder and lithium carbonate). Among them, by mass ratio, diamond powder: lithium carbonate powder = 5:95.

[0191] 8. Under a nitrogen atmosphere, in a reduction furnace at 550 °C, keep the single crystal piezoelectric composite film buried in the blackening powder for 3 h for a blackening reduction reaction. After the blackening reduction is completed, take it out from the blackening powder and remove the laid lithium tantalate single crystal wafer to obtain a blackened single crystal piezoelectric composite film.

[0192] 9. Fix the blackened single crystal piezoelectric composite film on a porous ceramic chuck of a polishing device, perform chemical mechanical polishing on the film layer until the reducing ions on the surface of the film layer are removed, and then perform RCA cleaning to obtain a clean surface.

[0193] The obtained blackened single crystal piezoelectric composite film successively includes a film layer, a silicon dioxide layer, a dielectric layer, and a single crystal silicon layer; among them, the material of the film layer is single crystal lithium tantalate.

[0194] Example VIII

[0195] A preparation method of a blackened single crystal piezoelectric composite film provided by Example VIII includes the following steps:

[0196] 1. Prepare a 400-μm silicon carbide wafer and a 300-μm lithium niobate wafer, respectively fix the silicon carbide wafer or the lithium niobate wafer on a porous ceramic chuck of a polishing device, perform chemical mechanical polishing to obtain a smooth surface, and then perform semiconductor RCA cleaning on the two wafers to obtain a clean surface. Among them, the lithium niobate wafer is a blackened lithium niobate wafer.

[0197] 2. Inject He+ into the lithium niobate wafer treated in step 1 by the stripping ion implantation method, so that the lithium niobate wafer is successively divided into a residual layer, a separation layer, and a film layer from the injection surface, and the injected He+ ions are distributed in the separation layer to obtain an injected wafer of single crystal lithium niobate.

[0198] When injecting He+ by the stripping ion implantation method, the injection dose parameters are: the injection dose is 3×1016 ions / cm2, and the injection energy is 35 keV.

[0199] 3. Inject argon ions into the cleaned silicon carbide wafer by ion implantation to fabricate a damaged layer of single crystal silicon as the dielectric layer, and its thickness is 5 μm.

[0200] 4. Fabricate a silicon dioxide layer on the dielectric layer by PECVD method, and then perform chemical mechanical polishing to obtain a smooth surface, with a thickness of 500 nm, and perform RCA cleaning to obtain a clean surface.

[0201] 5. Inject the single-crystal lithium niobate wafer into contact with the silicon dioxide layer, and bond them using the direct bonding method to obtain a bonded body.

[0202] 6. Under a nitrogen atmosphere, place the bonded body in an annealing furnace, keep it at 240 °C for 2 hours, and the bonded body separates at the separation layer to obtain a single-crystal piezoelectric composite film.

[0203] 7. Lay a single-crystal lithium niobate wafer on the film layer of the single-crystal piezoelectric composite film obtained after the treatment in step 6, and bury the single-crystal piezoelectric composite film with the laid single-crystal lithium niobate wafer in a blackening powder (a composite powder of iron powder, graphene, and lithium carbonate). Among them, by mass ratio, iron powder:graphene:lithium carbonate powder = 5:5:90.

[0204] 8. Under a nitrogen atmosphere, in a reduction furnace at 550 °C, keep the single-crystal piezoelectric composite film buried in the blackening powder for 3 h for a blackening reduction reaction. After the blackening reduction is completed, take it out from the blackening powder and remove the laid lithium tantalate wafer to obtain a blackened single-crystal piezoelectric composite film.

[0205] 9. Fix the blackened single-crystal piezoelectric composite film on a porous ceramic chuck of a polishing device, perform chemical mechanical polishing on the film layer until the reducing ions on the surface of the film layer are removed, and then perform RCA cleaning to obtain a clean surface.

[0206] The obtained blackened single-crystal piezoelectric composite film sequentially includes a film layer, a silicon dioxide layer, a dielectric layer, and a single-crystal silicon layer; wherein the material of the film layer is single-crystal lithium niobate.

[0207] For the same and similar parts among the various embodiments in this specification, reference can be made to each other. In particular, for the embodiments corresponding to the blackened single-crystal piezoelectric composite film, reference can be made to the part of the preparation method of the blackened single-crystal piezoelectric composite film.

[0208] The above has described the present application in detail in combination with specific embodiments and exemplary examples. However, these descriptions should not be construed as limiting the present application. Those skilled in the art understand that without departing from the spirit and scope of the present application, various equivalent substitutions, modifications, or improvements can be made to the technical solutions and their implementation manners of the present application, and these all fall within the scope of the present application. The protection scope of the present application is subject to the appended claims.

Claims

1. A preparation method of a blackened single-crystal piezoelectric composite film, characterized in that, Including: Prepare a first wafer and a substrate, wherein the first wafer is a lithium niobate wafer or a lithium tantalate wafer; Inject ions into the first wafer by ion implantation method, and sequentially divide the first wafer into a residual layer, a separation layer and a thin film layer; Bond the first wafer to the substrate to obtain a bonded body; Heat-treat the bonded body to separate the residual layer from the thin film layer to obtain a single-crystal piezoelectric composite thin film; Lay a second wafer or a reducing paper on the thin film layer of the single-crystal piezoelectric composite thin film to obtain a pre-preparation body; the second wafer has the same material as the first wafer; Bury the pre-preparation body in blackening powder, wherein the blackening powder includes reducing powder and lithium carbonate powder; In a reduction furnace, perform blackening reduction heat treatment on the single-crystal piezoelectric composite thin film buried in the blackening powder; Remove the second wafer or the reducing paper to obtain a blackened single-crystal piezoelectric composite thin film; Polish the surface of the thin film layer in the blackened single-crystal piezoelectric composite thin film.

2. The preparation method according to claim 1, characterized in that, By mass, the blackening powder includes 1-10 parts of reducing powder and 90-99 parts of lithium carbonate powder.

3. The preparation method according to claim 2, characterized in that, By mass, the blackening powder includes 5-10 parts of reducing powder and 90-95 parts of lithium carbonate powder.

4. The preparation method according to claim 1, wherein The reducing powder includes any one or more of iron powder, aluminum powder, zinc powder, magnesium powder, silicon powder, carbon powder.

5. The preparation method according to claim 1, characterized in that, The reducing powder includes a mixed powder of any one or more of iron powder, aluminum powder, zinc powder, magnesium powder, silicon powder, carbon powder and graphene.

6. The preparation method according to claim 1, characterized in that, In a reduction furnace, the temperature for performing blackening reduction heat treatment on the single-crystal piezoelectric composite thin film buried in the blackening powder is 300-600 °C, and the heat preservation time is 1-100 hours.

7. The preparation method according to claim 1, characterized in that, The ions implanted into the first wafer by ion implantation are helium ions, hydrogen ions, nitrogen ions, oxygen ions or argon ions, and the implantation dose is 2×10 16 ions / cm 2 -4×10 16 ions / cm 2 ; the implantation energy is 40 - 400 keV.

8. The preparation method according to claim 1, characterized in that, The preparation method further includes: Perform a cleaning treatment after polishing the surface of the thin film layer in the blackened single-crystal piezoelectric composite thin film.

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 thin film is prepared by the preparation method of the blackened single-crystal piezoelectric composite thin film according to any one of claims 1-9.

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