A single-crystal piezoelectric thin film and a method for manufacturing the same

Abstract

The application discloses a single-crystal piezoelectric film and a preparation method thereof. The method comprises the following steps: performing first annealing treatment on a processing surface of a single-crystal piezoelectric substrate to form a passivation layer on the processing surface; the single-crystal piezoelectric substrate is lithium niobate; performing ion implantation treatment on the single-crystal piezoelectric substrate from the processing surface, so that a piezoelectric film layer and a damage layer are formed in the single-crystal piezoelectric substrate, and a single-crystal piezoelectric substrate comprising the piezoelectric film layer is obtained; performing cleaning treatment on the single-crystal piezoelectric substrate by using a cleaning agent, and obtaining a cleaned single-crystal piezoelectric substrate; bonding the cleaned single-crystal piezoelectric substrate along the processing surface and a supporting substrate, and obtaining a bonding structure; performing peeling treatment on the bonding structure, so that the bonding structure is separated along the damage layer, and a single-crystal piezoelectric film is obtained. By forming the passivation layer on the surface of the single-crystal piezoelectric substrate, the piezoelectric film layer can be effectively prevented from being corroded in the preparation process, the complexity of the preparation process is reduced, the accuracy and uniformity of the product thickness are improved, and the product yield is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of functional materials, in particular to a single-crystal piezoelectric film and a preparation method thereof. BACKGROUND

[0002] Lithium niobate has excellent electro-optic, piezoelectric and nonlinear properties, and is a functional material with excellent performance. Compared with traditional lithium niobate bulk materials, lithium niobate thin films have great advantages in device performance, device miniaturization and integration, and have attracted widespread attention from academia and industry.

[0003] Currently, lithium niobate thin films are usually prepared by ion implantation and bonding transfer technology, that is, first, He ions are implanted in lithium niobate material to form a damage layer, then lithium niobate is bonded with a silicon substrate with an oxide layer to form a bonding structure, and then the bonding structure is processed to make lithium niobate peel off to form a lithium niobate thin film structure. The final lithium niobate thin film product needs to be annealed at high temperature and chemically mechanically polished to remove the damage layer formed by ion implantation on the surface. In this preparation process, in order to achieve good bonding of lithium niobate and silicon substrate, the lithium niobate thin film after ion implantation needs to be cleaned to remove the particles on the surface of the lithium niobate thin film. However, in the existing process, the conventional cleaning agent for removing particles (standard SC1: NH3·H2O+H2O2) will cause corrosion to the lithium niobate thin film, and the corrosion rate will change greatly with the change of the concentration of the liquid medicine, resulting in a certain deviation in the thickness of each lithium niobate wafer product after the bonding and peeling of lithium niobate, increasing the complexity of subsequent chemical mechanical polishing (CMP polishing) and reducing the yield of production.

[0004] Therefore, a single-crystal piezoelectric film and a preparation method thereof are needed, which can effectively protect the lithium niobate thin film from corrosion during the preparation process, ensure the accuracy and uniformity of the thickness of the final product, and improve the yield of the product. SUMMARY

[0005] In view of the problems existing in the prior art, the present application provides a single-crystal piezoelectric film and a preparation method thereof, which can effectively protect the lithium niobate thin film from corrosion during the preparation process, ensure the accuracy and uniformity of the thickness of the final product, and improve the yield of the product. The technical solution is as follows:

[0006] The present application provides a preparation method of a single-crystal piezoelectric film, comprising:

[0007] S1, performing first annealing treatment on the processing surface of a single-crystal piezoelectric substrate to form a passivation layer on the processing surface; wherein the material of the single-crystal piezoelectric substrate is single-crystal lithium niobate;

[0008] S2, performing ion implantation treatment on the single crystal piezoelectric substrate from the processing surface, so that a piezoelectric film layer and a damage layer are formed in the single crystal piezoelectric substrate, to obtain the single crystal piezoelectric substrate comprising the piezoelectric film layer; wherein the piezoelectric film layer is located between the passivation layer and the damage layer;

[0009] S3, performing cleaning treatment on the single crystal piezoelectric substrate comprising the piezoelectric film layer by using a cleaning agent, to obtain the single crystal piezoelectric substrate after cleaning;

[0010] S4, performing bonding treatment on the single crystal piezoelectric substrate after cleaning along the processing surface and a supporting substrate, to obtain a bonding structure;

[0011] S5, performing peeling treatment on the bonding structure, so that the bonding structure is separated along the damage layer, to obtain a single crystal piezoelectric film with the piezoelectric film layer as the surface.

[0012] Further, the element composition of the passivation layer is the same as that of the piezoelectric film layer, and the stoichiometric ratio of elements in the passivation layer is different from that in the piezoelectric film layer.

[0013] Further, the stoichiometric ratio of lithium, oxygen and niobium in the passivation layer is (0.1-0.8):(2.5-3):1.

[0014] Further, the first annealing temperature of the first annealing treatment is 200-500℃, and the annealing environment of the first annealing treatment is at least one of N2, O2 and Ar.

[0015] Further, the implantation ion of the ion implantation treatment is He ion or H ion, the implantation energy is 200-300KeV, and the implantation dose is 1х10 16 ~5х10 16 / cm 2 .

[0016] Further, the cleaning time of the cleaning treatment is 3-30min, the cleaning agent is composed of deionized water, hydrogen peroxide and ammonia, and the mass ratio of deionized water, hydrogen peroxide and ammonia in the cleaning agent is (0-10):1:1.

[0017] Further, the corrosion rate ratio of the passivation layer and the piezoelectric film layer in the cleaning agent is less than 1:10.

[0018] Further, the peeling treatment is a second annealing treatment, the second annealing temperature of the second annealing treatment is 100-300℃, and the annealing time is 3-100h; the annealing environment of the second annealing treatment is at least one of N2, O2 and Ar.

[0019] Further, after the peeling treatment is performed on the bonding structure so that the bonding structure is separated along the damage layer to obtain a single-crystal piezoelectric thin film with a surface of the piezoelectric thin film layer, the preparation method further comprises:

[0020] performing surface treatment on the single-crystal piezoelectric thin film to remove the damage layer.

[0021] The application further provides a single-crystal piezoelectric thin film obtained by the above preparation method of a single-crystal piezoelectric thin film, comprising a support substrate, a passivation layer and a piezoelectric thin film layer, wherein the passivation layer is located between the support substrate and the piezoelectric thin film layer, and the thickness of the passivation layer is 2-20 nm.

[0022] Further, the thickness deviation of the passivation layer is less than 0.5 nm.

[0023] Further, the support substrate is at least one of silicon, silicon carbide, sapphire and quartz. Further, the support substrate comprises a support layer and an isolation layer, and the isolation layer is located between the support layer and the passivation layer.

[0024] The application has the following beneficial effects:

[0025] The application forms a passivation layer on the surface of a single-crystal piezoelectric substrate to cover the piezoelectric thin film layer, which can effectively avoid the piezoelectric thin film layer from being corroded during cleaning treatment, improve the accuracy and uniformity of product thickness, and improve product yield. Meanwhile, avoiding the corrosion of the piezoelectric thin film layer can also reduce the complexity of subsequent surface treatment to some extent, further improve product yield, reduce the complexity of the preparation process, make the preparation process simpler and easier to implement, and reduce production cost. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the application, the drawings used in the embodiments will be briefly introduced as follows, wherein the same parts are denoted by the same reference numerals. Obviously, the drawings described below are only some embodiments of the application, and those skilled in the art can also obtain other drawings according to these drawings without any creative effort.

[0027] Figure 1 A logic diagram of the preparation method of a single-crystal piezoelectric thin film in one possible embodiment of the application;

[0028] Figure 2 A flowchart of the preparation method of a single-crystal piezoelectric thin film in one possible embodiment of the application;

[0029] Figure 3A flow chart of a preparation method of a single-crystal piezoelectric thin film in Example 2 of the present application;

[0030] Figure 4 A structural schematic diagram of a single-crystal piezoelectric thin film in Example 2;

[0031] Figure 5 A flow chart of a preparation method of a single-crystal piezoelectric thin film in Example 3 of the present application;

[0032] Figure 6 A structural schematic diagram of a single-crystal piezoelectric thin film in Example 3;

[0033] Figure 7 A thickness distribution schematic diagram of a single-crystal piezoelectric thin film prepared in the present application and a single-crystal piezoelectric thin film in a comparative example.

[0034] In the figure, the reference signs correspond to: 1-single-crystal piezoelectric substrate, 11-passivation layer, 12-piezoelectric thin film layer, 13-damage layer, 2-supporting substrate, 21-supporting layer, 22-defect layer, 23-isolation layer. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present application will be clearly and completely described in combination with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application, and therefore should not be understood as limiting the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0036] It should be noted that the terms "first", "second", and the like in the specification and claims of the present application and the accompanying drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than that described below or described below. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or server including a series of steps or units does not necessarily limit to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0037] Embodiment 1

[0038] In order to overcome the problem that the surface of the lithium niobate thin film is corroded during cleaning in the prior art, the present application provides a preparation method of a single-crystal piezoelectric thin film, as shown in the accompanying Figure 1 and the accompanying Figure 2 The preparation method comprises:

[0039] S1, performing a first annealing treatment on a processing surface of a single-crystal piezoelectric substrate to form a passivation layer on the processing surface; wherein the single-crystal piezoelectric substrate is made of single-crystal lithium niobate;

[0040] S2, performing an ion implantation treatment on the single-crystal piezoelectric substrate from the processing surface to form a piezoelectric film layer and a damage layer in the single-crystal piezoelectric substrate, to obtain the single-crystal piezoelectric substrate including the piezoelectric film layer; wherein the piezoelectric film layer is located between the passivation layer and the damage layer;

[0041] S3, performing a cleaning treatment on the single-crystal piezoelectric substrate including the piezoelectric film layer by using a cleaning agent, to obtain the single-crystal piezoelectric substrate after cleaning;

[0042] S4, performing a bonding treatment on the single-crystal piezoelectric substrate after cleaning along the processing surface and a supporting substrate, to obtain a bonding structure;

[0043] S5, performing a peeling treatment on the bonding structure to separate the bonding structure along the damage layer, to obtain a single-crystal piezoelectric film with the piezoelectric film layer as a surface.

[0044] Specifically, in one possible implementation, the first annealing temperature of the first annealing treatment in the S1 step is 200-500°C, and the annealing environment is at least one of N2, O2 and Ar; in the S1 step, one side surface of the single-crystal piezoelectric substrate is the processing surface, and the processing surface is placed in the atmosphere of N2, O2 and / or Ar for the first annealing treatment, so that a passivation layer is formed at the position of the processing surface, which covers the underlying single-crystal piezoelectric substrate material and plays a protective role to avoid the underlying single-crystal piezoelectric substrate material from being corroded in the subsequent preparation process.

[0045] Specifically, in one optional implementation, the thickness of the passivation layer is 2-20 nm, which achieves particularly satisfactory effect in terms of corrosion resistance, and the thickness uniformity of the single-crystal piezoelectric film is also obviously improved; in one preferred implementation, the thickness of the passivation layer is 2-10 nm, the passivation layer with this thickness can play a good role in corrosion resistance, so that the single-crystal piezoelectric film has the desired thickness uniformity, and the waste of lithium niobate raw materials and the possible adverse effects on the performance of the final product can be avoided.

[0046] Specifically, in the present embodiment, the single-crystal piezoelectric substrate is made of single-crystal lithium niobate, which has excellent electro-optic, piezoelectric and nonlinear properties; and the passivation layer is obtained by annealing the single-crystal lithium niobate raw material, the element composition of the passivation layer is the same as that of the initial single-crystal piezoelectric substrate, i.e., single-crystal lithium niobate; at the same time, the stoichiometric ratio of the elements in the passivation layer is different from that in the initial single-crystal piezoelectric substrate.

[0047] Specifically, in one possible implementation, the stoichiometric ratio of lithium element, oxygen element and niobium element in the passivation layer is (0.1-0.8):(2.5-3):1.

[0048] Specifically, in the S2 step, ion implantation is performed on the single-crystal piezoelectric substrate from the processing surface, as shown in FIG. 2B. At this time, the position of the processing surface has formed a passivation layer, and the ion implantation is performed through the passivation layer to form a damage layer with a certain thickness at a certain depth below the passivation layer. At the same time of forming the damage layer, a layer between the damage layer and the passivation layer becomes a piezoelectric film layer, which is the same in element composition and stoichiometric ratio as the initial single-crystal piezoelectric substrate, and the piezoelectric film layer is the same material as the single-crystal lithium niobate film layer, which is the functional material layer of the final product single-crystal piezoelectric film. Figure 2

[0049] Specifically, in one possible implementation, the implantation ions for ion implantation in the S2 step are He ions or H ions, the implantation energy is 200-300 KeV, and the implantation dose is 1х10 16 ~5х10 16 / cm 2 .

[0050] Specifically, the cleaning treatment in the S3 step is to clean the single-crystal piezoelectric substrate including the piezoelectric film layer in the S2 step, so as to remove the particles on the surface thereof, so that good bonding can be achieved when the lithium niobate and the support substrate are subjected to plasma-activated bonding reaction in the subsequent step, and impurities and structural instability are avoided, and the yield of the final product single-crystal piezoelectric film is improved.

[0051] In one possible implementation, the cleaning time of the cleaning treatment is 3-30 min, which can meet the requirement of the subsequent preparation process on the surface cleanliness of the single-crystal piezoelectric substrate (i.e., lithium niobate) including the piezoelectric film layer. The cleaning agent used in the cleaning treatment can be selected from a cleaning agent composed of deionized water, hydrogen peroxide and ammonia, wherein the mass ratio of the deionized water, the hydrogen peroxide and the ammonia can be selected as (0-10):1:1 according to actual needs, and the cleaning effect is good and the cleaning efficiency is high. In another possible implementation, the cleaning agent can be SC1 cleaning solution, which is a mixture of ammonia water, hydrogen peroxide and water, and can react with the surface of the single-crystal piezoelectric substrate at room temperature to remove the particulate impurities and polymers on the surface of the single-crystal piezoelectric substrate including the piezoelectric film layer.

[0052] ​Specifically, the corrosion rate ratio of the passivation layer to the piezoelectric thin film layer in the cleaning agent is less than 1:10, the corrosion rate of the passivation layer is much slower than that of the piezoelectric thin film layer, which can greatly reduce the corrosion amount of the passivation layer, reduce the thickness deviation of the passivation layer generated in the preparation process, and is conducive to making the thickness of the final product closer to the expected thickness; and under the same cleaning time, the corrosion amount of the passivation layer is much smaller than that of the piezoelectric thin film layer, which can not only make the cleaning agent stay for enough time to achieve the cleaning purpose, but also avoid the corrosion perforation of the passivation layer, which affects the performance of the piezoelectric thin film layer.

[0053] Specifically, the peeling treatment in S5 is to separate the bonding structure along the damage layer, so as to expose the piezoelectric thin film layer; in a possible embodiment, the peeling treatment can be selected as a second annealing treatment, which is performed at a second annealing temperature of 100-300℃, the annealing time is 3-100h, and the annealing environment is at least one of N2, O2 and Ar, so that the damage layer can be fully separated, and at the same time, the structure outside the damage layer will not be damaged, ensuring the stability of the structure and the excellent performance of the single crystal piezoelectric thin film final product, and improving the yield of the final product.

[0054] Specifically, after the peeling treatment of the bonding structure is performed, so that the bonding structure is separated along the damage layer, and a single crystal piezoelectric thin film with the surface being the piezoelectric thin film layer is obtained, the preparation method further comprises:

[0055] The single crystal piezoelectric thin film is subjected to surface treatment to remove the damage layer.

[0056] In S5, when the piezoelectric thin film layer is separated along the damage layer, the surface of the piezoelectric thin film layer may still have a certain amount of damage layer, and the surface after the peeling treatment is not flat, which will adversely affect the performance of the single crystal piezoelectric thin film; the surface treatment can remove the remaining damage layer, increase the flatness and smoothness of the surface of the piezoelectric thin film layer, and is conducive to improving the product performance; and in a possible embodiment of the present specification, the surface treatment can include high-temperature annealing treatment and chemical mechanical polishing treatment, which has high removal efficiency and good surface flatness; wherein the annealing temperature of the high-temperature annealing treatment can be 300-1000℃, and the annealing atmosphere can be selected from at least one of N2, O2 and Ar.

[0057] The present embodiment also provides a single crystal piezoelectric thin film obtained by the above-mentioned single crystal piezoelectric thin film preparation method, such as Figure 2As shown, the single-crystal piezoelectric thin film includes a support substrate 2, a passivation layer 11 and a piezoelectric thin film layer 12, wherein the passivation layer 11 is located between the support substrate 2 and the piezoelectric thin film layer 12, the thickness of the passivation layer is 2-20 nm, preferably 2-10 nm, which can effectively protect the piezoelectric thin film layer 12 during the cleaning process, prevent the piezoelectric thin film layer 12 from being corroded by the cleaning agent, so that the deviation between the thickness of the produced single-crystal piezoelectric thin film and the expected thickness is small, and the thickness is uniform everywhere, thereby improving the product yield and ensuring excellent product performance.

[0058] Specifically, the etching rate of the cleaning agent on the passivation layer 11 is low, so the total etching amount of the passivation layer 11 is also correspondingly reduced during the entire preparation process, which is beneficial to maintain the thickness of the passivation layer 11 within the expected thickness; in this embodiment, the thickness deviation of the passivation layer 11 is less than 0.5 nm, which is extremely small and even negligible, which is beneficial to reduce the deviation between the thickness of the single-crystal piezoelectric thin film and the expected thickness, and improve the product performance.

[0059] Specifically, in one possible embodiment of the present specification, the support substrate 2 can select a support substrate of silicon material, or can select a support substrate of silicon carbide, sapphire or quartz material, which has stable properties and stable support.

[0060] Embodiment 2

[0061] As shown in the accompanying Figure 3 and the accompanying Figure 4 As shown, the difference between this embodiment and embodiment 1 is that the support substrate 2 includes a support layer 21 and an isolation layer 23, wherein the isolation layer 23 is located between the support layer 21 and the passivation layer 11, the support layer 21 plays a supporting role, and the isolation layer 23 plays an optical isolation role, i.e. the structure of the single-crystal piezoelectric thin film from bottom to top is the support layer 21, the isolation layer 23, the passivation layer 11 and the piezoelectric thin film layer 12; in one possible embodiment of the present specification, the material of the support layer 21 can be selected to be at least one of silicon, silicon carbide, sapphire and quartz; in another possible embodiment of the present specification, the material of the isolation layer 23 can be selected to be SiO2 and AlN, etc., which is formed above the support layer 21 by physical vapor deposition or chemical vapor deposition.

[0062] Then, in the bonding process in step S4, the cleaned single-crystal piezoelectric substrate is bonded along the processing surface and the surface of the isolation layer in the support substrate to obtain a bonding structure.

[0063] In one specific embodiment of the present embodiment, the preparation method of the single-crystal piezoelectric thin film can include the following steps:

[0064] At a first annealing temperature of 300°C, the processing surface of the lithium niobate substrate is subjected to a first annealing process to form a passivation layer on the processing surface;

[0065] The lithium niobate substrate is subjected to ion implantation treatment from the processing surface, the implantation ions are He ions, the implantation energy is 240 KeV, and the implantation dose is 4x10 16 / cm 2 , so that a piezoelectric film layer and a damage layer are formed in the lithium niobate substrate, and a lithium niobate substrate including a piezoelectric film layer is obtained;

[0066] The lithium niobate substrate including the piezoelectric film layer is cleaned with a cleaning agent with a concentration of H2O2:NH3:H2O = 1:1:8 for 3 min, and a cleaned lithium niobate substrate is obtained;

[0067] A support substrate including a silicon oxide isolation layer and a silicon support layer is taken, and the cleaned lithium niobate substrate is subjected to bonding treatment along the processing surface and the surface of the isolation layer in the support substrate, and a bonding structure is obtained;

[0068] The bonding structure is subjected to second annealing treatment at a second annealing temperature of 250°C for 3h, so that the bonding structure is separated along the damage layer, and a single-crystal piezoelectric film with a surface of a piezoelectric film layer is obtained;

[0069] By high-temperature annealing and chemical mechanical polishing, the damage layer on the surface of the single-crystal piezoelectric film is removed, and a final product of the single-crystal piezoelectric film is obtained, which has a small deviation between the thickness and the expected thickness, and the thickness is uniform everywhere.

[0070] Example 3

[0071] As shown in FIG. 1, the single-crystal piezoelectric film includes a support substrate 2, a lithium niobate substrate 1, and a passivation layer 11. The support substrate 2 includes a support layer 21 and an isolation layer 23. The lithium niobate substrate 1 includes a piezoelectric film layer 12 and a damage layer 13. The passivation layer 11 is located between the lithium niobate substrate 1 and the isolation layer 23, and the piezoelectric film layer 12 is located between the passivation layer 11 and the damage layer 13. Figure 5 As shown in FIG. 2, the single-crystal piezoelectric film includes a support substrate 2, a lithium niobate substrate 1, and a passivation layer 11. The support substrate 2 includes a support layer 21, a defect layer 22, and an isolation layer 23. The lithium niobate substrate 1 includes a piezoelectric film layer 12 and a damage layer 13. The passivation layer 11 is located between the lithium niobate substrate 1 and the isolation layer 23, and the piezoelectric film layer 12 is located between the passivation layer 11 and the damage layer 13. Figure 6 As shown in FIG. 2, the single-crystal piezoelectric film includes a support substrate 2, a lithium niobate substrate 1, and a passivation layer 11. The support substrate 2 includes a support layer 21, a defect layer 22, and an isolation layer 23. The lithium niobate substrate 1 includes a piezoelectric film layer 12 and a damage layer 13. The passivation layer 11 is located between the lithium niobate substrate 1 and the isolation layer 23, and the piezoelectric film layer 12 is located between the passivation layer 11 and the damage layer 13.

[0072] In a specific embodiment of the present embodiment, the method for preparing the single-crystal piezoelectric film can include the following steps:

[0073] The processing surface of the lithium niobate substrate is subjected to first annealing treatment at a first annealing temperature of 350°C to form a passivation layer on the processing surface;

[0074] The lithium niobate substrate is subjected to ion implantation treatment from the processing surface, the implanted ions are He ions, the implantation energy is 280 KeV, and the implantation dose is 4.5x10 16 / cm 2 , so that a piezoelectric film layer and a damage layer are formed in the lithium niobate substrate, and a lithium niobate substrate including a piezoelectric film layer is obtained;

[0075] The lithium niobate substrate including the piezoelectric film layer is cleaned with a cleaning agent with a concentration of H2O2:NH3:H2O = 1:1:6 for 10 min, and a cleaned lithium niobate substrate is obtained.

[0076] A support substrate including a silicon oxide isolation layer, a defect layer, and a silicon support layer is taken, and the cleaned lithium niobate substrate is subjected to bonding treatment along the processing surface and the surface of the isolation layer in the support substrate, and a bonding structure is obtained.

[0077] The bonding structure is subjected to a second annealing treatment at a second annealing temperature of 250°C for 6h, so that the bonding structure is separated along the damage layer, and a single-crystal piezoelectric film with a surface of a piezoelectric film layer is obtained.

[0078] By high-temperature annealing and chemical mechanical polishing, the damage layer on the surface of the single-crystal piezoelectric film is removed, and a final product of the single-crystal piezoelectric film is obtained, which has a small deviation between the thickness and the expected thickness, and the thickness is uniform.

[0079] Comparative Example 1

[0080] This comparative example does not perform the first annealing treatment of step S1 nor the cleaning treatment of step S3, and the remaining steps are the same as those of Example 1.

[0081] Comparative Example 2

[0082] This comparative example does not perform the first annealing treatment of step S1, and the remaining steps are the same as those of Example 1.

[0083] The thickness distribution of the single-crystal piezoelectric film prepared in this application and the above comparative examples is detected, as shown in FIG. 1. Figure 7As shown, the left side of the figure a) is a schematic diagram of the thickness distribution of the single crystal piezoelectric film prepared in Comparative Example 1, the middle figure b) is a schematic diagram of the thickness distribution of the single crystal piezoelectric film prepared in the present application, and the right side of the figure c) is a schematic diagram of the thickness distribution of the single crystal piezoelectric film prepared in Comparative Example 2; by comparing Comparative Example 1 with Comparative Example 2, it is shown in figure c) that the thickness distribution is very uneven everywhere, and compared with the thickness distribution shown in figure a), it is obviously much thinner than the single crystal piezoelectric film without cleaning treatment, that is, the thickness deviation between the single crystal piezoelectric films prepared in Comparative Example 1 and Comparative Example 2 is large, which shows that the cleaning treatment in S3 step will greatly thin the single crystal piezoelectric film and cause the thickness of the single crystal piezoelectric film to be uneven; while the thickness deviation of the single crystal piezoelectric film prepared in the present application and the single crystal piezoelectric film in Comparative Example 1 is very small, which represents that the passivation layer formed in S1 step plays a very effective protective role on the piezoelectric film layer, greatly avoids the corrosion of the cleaning treatment on the piezoelectric film layer, and compared with Comparative Example 2, it is also shown in figure b) that the thickness of the single crystal piezoelectric film of the present application is relatively uniform everywhere, which shows that the protection of the passivation layer can also be beneficial to improve the uniformity of the product thickness, so as to greatly improve the product yield.

[0084] The above description is only some embodiments of the present application and is not used to limit the present application. It should be understood by those skilled in the art that the present application can have various changes and improvements. Any modification, equivalent replacement and improvement made according to the present application fall within the scope of protection required by the present application.

Claims

1. A method for preparing a single-crystal piezoelectric thin film, characterized in that, The preparation method comprises the following steps: S1, a first annealing treatment is performed on a processing surface of a single-crystal piezoelectric substrate to form a passivation layer on the processing surface; wherein the single-crystal piezoelectric substrate is made of single-crystal lithium niobate; the thickness of the passivation layer is 2-10 nm, and the thickness deviation of the passivation layer is less than 0.5 nm; S2, ion implantation treatment is performed on the single-crystal piezoelectric substrate from the processing surface, so that a piezoelectric film layer and a damage layer are formed in the single-crystal piezoelectric substrate, and the single-crystal piezoelectric substrate comprising the piezoelectric film layer is obtained; wherein the piezoelectric film layer is located between the passivation layer and the damage layer, the element composition of the passivation layer is the same as that of the piezoelectric film layer, the element composition and the stoichiometric ratio of the piezoelectric film layer and the initial single-crystal piezoelectric substrate are the same, the stoichiometric ratio of the elements in the passivation layer is different from that in the piezoelectric film layer, and the stoichiometric ratio of lithium, oxygen and niobium in the passivation layer is (0.1-0.8):(2.5-3):1; S3, a cleaning agent is used to clean the single-crystal piezoelectric substrate comprising the piezoelectric film layer, and the cleaned single-crystal piezoelectric substrate is obtained; S4, the cleaned single-crystal piezoelectric substrate is bonded to a support substrate along the processing surface, and a bonding structure is obtained; S5, a peeling treatment is performed on the bonding structure, so that the bonding structure is separated along the damage layer, and a single-crystal piezoelectric film with the piezoelectric film layer as the surface is obtained.

2. The production method according to claim 1, characterized by, The first annealing temperature of the first annealing treatment is 200-500°C, and the annealing environment of the first annealing treatment is at least one of N2, O2 and Ar.

3. The preparation method according to claim 1, characterized in that, The implanting ion of the ion implantation treatment is He ion or H ion, the implanting energy is 200-300 KeV, the implanting dose is 1x10 16 ~5x10 16 / cm 2 .

4. The method of claim 1, wherein, The cleaning time of the cleaning treatment is 3-30 min, the cleaning agent is composed of deionized water, hydrogen peroxide and ammonia, and the mass ratio of deionized water, hydrogen peroxide and ammonia in the cleaning agent is (0-10):1:

1.

5. The preparation method according to claim 4, characterized in that, The corrosion rate ratio of the passivation layer and the piezoelectric film layer in the cleaning agent is less than 1:

10.

6. The method of claim 1, wherein, The peeling treatment is a second annealing treatment, the second annealing temperature of the second annealing treatment is 100-300°C, and the annealing time is 3-100 h; the annealing environment of the second annealing treatment is at least one of N2, O2 and Ar.

7. The preparation method according to claim 1, characterized in that, After the peeling treatment is performed on the bonding structure, so that the bonding structure is separated along the damage layer, and a single-crystal piezoelectric film with the piezoelectric film layer as the surface is obtained, the preparation method further comprises: a surface treatment is performed on the single-crystal piezoelectric film to remove the damage layer.

8. A single crystal piezoelectric thin film, characterized by The single-crystal piezoelectric film is obtained by the preparation method of the single-crystal piezoelectric film according to any one of claims 1-7, comprising a support substrate, a passivation layer and a piezoelectric film layer, the passivation layer is located between the support substrate and the piezoelectric film layer, and the thickness of the passivation layer is 2-10 nm.

9. The single crystal piezoelectric thin film of claim 8, wherein the piezoelectric thin film is a thin film of LiNb03, LiTa03, KNb03, KTa03, or a solid solution thereof. The support substrate is at least one of silicon, silicon carbide, sapphire and quartz.

10. The single-crystal piezoelectric thin film according to claim 8, characterized in that, The support substrate comprises a support layer and an isolation layer, and the isolation layer is located between the support layer and the passivation layer.

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