A method for producing a multilayer film and a multilayer film

Abstract

The application discloses a multilayer film preparation method and a multilayer film. The method mainly comprises the following steps: preparing a first material layer, and then stacking a plurality of second material layers on the surface of the first material layer. In the embodiment of the application, each second material layer comprises a second substrate which is composed of a ferroelectric single crystal material. By using the method, a plurality of film layers composed of the ferroelectric single crystal material can be prepared in the multilayer film, and the application of the ferroelectric single crystal material in the multilayer film is facilitated.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor processing, and in particular, to a multilayer film preparation method and a multilayer film. BACKGROUND

[0002] With the development of material processing technology and process, thin film materials are increasingly widely used in devices. Especially, the multilayer film including a plurality of stacked thin film layers is applied in various semiconductor devices. For example, the semiconductor devices such as laser, memory, sensor, capacitor are composed of multilayer films.

[0003] At present, the multilayer film can be prepared by growth or deposition process. The commonly used growth or deposition process mainly includes magnetron sputtering, chemical vapor deposition, atomic layer growth, molecular beam epitaxy, etc. However, the current growth or deposition process cannot directly prepare ferroelectric single crystal material in the multilayer film, which limits the application of ferroelectric single crystal material in the multilayer film.

[0004] Therefore, the current preparation process of the multilayer film needs further research. SUMMARY

[0005] The present application provides a multilayer film preparation method and a multilayer film, which are used for preparing a plurality of thin film layers composed of ferroelectric single crystal material in the multilayer film.

[0006] In the first aspect, the present application provides a multilayer film preparation method, which mainly includes: preparing a first material layer, and then stacking a plurality of second material layers on the surface of the first material layer. In the present application, each second material layer includes a second substrate composed of ferroelectric single crystal material.

[0007] The multilayer film preparation method provided by the present application is advantageous for preparing a plurality of thin film layers composed of ferroelectric single crystal material in the multilayer film. Specifically, the present application stacks a plurality of second material layers on the surface of the first material layer, and each second material layer includes a second substrate. Therefore, the obtained multilayer film can include a plurality of second substrates composed of ferroelectric single crystal material, and the second substrate is also composed of ferroelectric single crystal material, thereby achieving the preparation of a plurality of thin film layers composed of ferroelectric single crystal material in the multilayer film.

[0008] For example, the ferroelectric single crystal material in the present application can be any one of lithium niobate, black lithium niobate, doped lithium niobate, lithium tantalate, black lithium tantalate, doped lithium tantalate, bismuth ferrite, barium titanate, barium strontium titanate, strontium titanate, etc.

[0009] In the embodiments of the present application, the plurality of second material layers can be prepared first, and then the plurality of second material layers are stacked on the surface of the first material layer. It can be understood that, in addition to the second substrate, the second material layer can also include other thin film layers.

[0010] In a possible implementation, for each second material layer, a second intermediate layer can be prepared on the surface of the second substrate, thereby obtaining the second material layer. In the embodiments of the present application, the function of the second material layer can be flexibly designed according to the application scenario. For example, the second intermediate layer can be a sacrificial layer, a buffer layer, a contact layer, and the like, which will not be enumerated one by one in the embodiments of the present application

[0011] In another possible implementation, for each second material layer, a second intermediate layer can be prepared on the surface of the second substrate; and then a second bonding layer is prepared on the surface of the second intermediate layer away from the surface of the second substrate, thereby obtaining the second material layer. Some thin film materials cannot be directly bonded, or the bonding effect is not good. Therefore, the second bonding layer can be prepared to optimize the bonding effect.

[0012] In the case where the second material layer includes the second substrate and other thin film layers (such as the second intermediate layer and the second bonding layer), the first surfaces of the plurality of second material layers are all arranged towards the first material layer, wherein the first surface of each second material layer can be understood as the surface of the second material layer away from the second substrate.

[0013] Similarly to the preparation of the second material layer, in a possible implementation, a first intermediate layer can also be prepared on the surface of the first substrate when the first material layer is prepared, thereby obtaining the first material layer.

[0014] In another possible implementation, when the first material layer is prepared, a first intermediate layer can be prepared first on the surface of the first substrate, and then a first bonding layer is prepared on the surface of the first intermediate layer away from the surface of the first substrate, thereby obtaining the first material layer.

[0015] The effects of the first intermediate layer and the first bonding layer can be referred to the second intermediate layer and the second bonding layer respectively, which will not be described herein.

[0016] It can be understood that, in the case where the first material layer includes the first substrate and other thin film layers (such as the first intermediate layer and the first bonding layer), the plurality of second material layers should be arranged on the surface of the first material layer away from the first substrate, so as to maintain the bearing of the first substrate.

[0017] In the embodiments of the present application, the second material layers can be further separated by third intermediate layers to more flexibly apply the multilayer film to different structures. For example, in one possible implementation, when the plurality of second material layers are stacked on the surface of the first material layer, one second material layer can be disposed on the surface of the first material layer, and a third intermediate layer can be prepared on the surface of the disposed second material layer, and then another second material layer can be disposed on the surface of the third intermediate layer away from the surface of the disposed second material layer, until the plurality of second material layers are disposed.

[0018] In another possible implementation, when the plurality of second material layers are stacked on the surface of the first material layer, one second material layer can be disposed on the surface of the first material layer, a third intermediate layer can be prepared on the surface of the disposed second material layer, and then a third bonding layer can be prepared on the surface of the third intermediate layer away from the surface of the disposed second material layer, and another second material layer can be disposed on the surface of the third bonding layer away from the surface of the disposed second material layer, until the plurality of second material layers are disposed.

[0019] The effects of the third intermediate layer and the third bonding layer can be respectively referred to the second intermediate layer and the second bonding layer, which will not be repeated here.

[0020] Generally, the film thickness of the ferroelectric single crystal material in the multilayer film has certain requirements. Therefore, before the third intermediate layer is prepared on the surface of the disposed second material layer, the second surface of the disposed second material layer can be thinned to make the second substrate in the disposed second material layer reach the target thickness, wherein the second surface of the second material layer can be understood as the surface of the second substrate in the second material layer; the second surface of the disposed second material layer can be planarized; and then the third intermediate layer can be prepared on the second surface of the second material layer.

[0021] In a second aspect, the embodiments of the present application also provide a multilayer film. The multilayer film can be prepared by any of the preparation methods of the multilayer film provided in the first aspect. The technical effects of the corresponding solutions in the second aspect can be referred to the technical effects of the corresponding solutions in the first aspect, and the repeated parts will not be described in detail. For example, the multilayer film provided in the embodiments of the present application mainly includes a plurality of second material layers and a first material layer; wherein the plurality of second material layers are stacked on the surface of the first material layer, and each second material layer includes a second substrate composed of a ferroelectric single crystal material.

[0022] For example, the ferroelectric single crystal material in the embodiments of the present application can be any one of lithium niobate, black lithium niobate, doped lithium niobate, lithium tantalate, black lithium tantalate, doped lithium tantalate, bismuth ferrite, barium titanate, barium strontium titanate, strontium titanate, etc.

[0023] In addition to the second substrate, other film layers can be included in the second material layer. In one possible implementation, each second material layer can further include a second intermediate layer disposed on a surface of the second substrate.

[0024] In another possible implementation, each second material layer can further include a second intermediate layer and a second bonding layer; the second intermediate layer is disposed on a surface of the second substrate, and the second bonding layer is disposed on a surface of the second intermediate layer away from the surface of the second substrate.

[0025] In the case where, in addition to the second substrate, other film layers are included in the second material layer, the first surface of each second material layer is disposed towards the first material layer, where the first surface of the second material layer can be understood as a surface of the second material layer away from the second substrate.

[0026] Similar to the second material layer, in addition to the first substrate, other film layers can be included in the first material layer. In one possible implementation, the first material layer can include the first substrate and a first intermediate layer disposed on a surface of the first substrate.

[0027] In another possible implementation, the first material layer can include the first substrate, the first intermediate layer, and a first bonding layer; the first intermediate layer is disposed on a surface of the first substrate, and the first bonding layer is disposed on a surface of the first intermediate layer away from the surface of the first substrate.

[0028] In the case where, in addition to the first substrate, other film layers are included in the first material layer, a plurality of second material layers can be stacked and disposed on a surface of the first material layer away from the first substrate.

[0029] To adapt to different application scenarios, in one possible implementation, a third intermediate layer can be further disposed between adjacent second material layers.

[0030] In another possible implementation, a third intermediate layer and a third bonding layer can be further stacked and disposed between adjacent second material layers; the third intermediate layer is disposed close to the first substrate, and the third bonding layer is disposed away from the first substrate.

[0031] For example, the thickness of the second substrate in the multilayer film can be 10-100 μm.

[0032] These aspects or other aspects of the present application will be more apparent in the following description of the embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 A multilayer film preparation method flowchart is provided for the embodiments of the present application;

[0034] Figure 2A multi-layer thin film structure schematic diagram provided for an embodiment of the present application;

[0035] Figures 3a-3e A first material layer structure schematic diagram provided for an embodiment of the present application;

[0036] Figures 4a-4e A second material layer structure schematic diagram provided for an embodiment of the present application;

[0037] Figure 5 An intermediate structure schematic diagram in a multi-layer thin film preparation process provided for an embodiment of the present application;

[0038] Figure 6 A flowchart of setting a second material layer on the surface of a first material layer provided for an embodiment of the present application;

[0039] Figure 7 An intermediate structure schematic diagram in a multi-layer thin film preparation process provided for an embodiment of the present application;

[0040] Figure 8 An intermediate structure schematic diagram in a multi-layer thin film preparation process provided for an embodiment of the present application. DETAILED DESCRIPTION

[0041] With the development of material processing technology and process, the application of thin film materials in devices is becoming more and more widespread. Especially multi-layer thin films, which are widely used in various semiconductor devices. For example, laser, memory, sensor, capacitor and other semiconductor devices are mostly composed of multi-layer thin films.

[0042] Generally, a multi-layer thin film is composed of multiple thin film layers stacked together, and different layers of thin film layers can be composed of the same or different materials. At present, multi-layer thin films are mainly prepared by growing or depositing processes to prepare multiple thin film layers on a substrate, thereby obtaining a multi-layer thin film. For example, magnetron sputtering, chemical vapor deposition, atomic layer growth, molecular beam epitaxy, etc. can be used to prepare multi-layer thin films. Through these growth or deposition processes, very many types of thin film materials can be prepared, and the grown film surface is flat, the structure is good, and the cost is low, which can meet many application scenarios.

[0043] However, in the current multi-layer thin film preparation process, most of the ferroelectric single crystal materials cannot be prepared by growth or deposition process, which limits the application of these materials in multi-layer thin films. Therefore, the application range of the growth or deposition process still has some deficiencies, and at present, a multi-layer thin film preparation method (process) is urgently needed to complement the growth or deposition process, so that ferroelectric single crystal materials can be applied in multi-layer thin films.

[0044] Therefore, the application provides a multilayer thin film preparation method.

[0045] In order to make the purpose, technical scheme and advantages of the application clearer, the application will be described in further detail below with reference to the drawings. The specific operation method in the method embodiment can also be applied to the device embodiment or the system embodiment. It should be noted that in the description of the application, "at least one" means one or more, and the plurality means two or more. Therefore, in the application embodiment, "plurality" can also be understood as "at least two". "And / or" describes the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which means that there are three cases of A alone, A and B together, and B alone. In addition, the character " / ", if not specially stated, generally represents an "or" relationship between the front and rear associated objects. In addition, it should be understood that in the description of the application, "first", "second", etc. are used only for the purpose of distinguishing the description and cannot be understood as indicating or implying relative importance or indicating or implying order.

[0046] For the sake of convenience, specific spatial relative terminology is used in the following description. This is not intended to be limiting. The terms "upper" and "lower" designate directions in the drawings to which reference is made. The terminology includes the above specifically mentioned words, derivatives thereof, and words of similar import. Above, over, upper surface, upper, and the like are used to describe the spatial relationship of one device or feature to another device or feature as illustrated in the figures. It will be understood that spatial relative terms are intended to encompass different orientations of the device in addition to the orientation depicted in the figures. For example, if a device in the figures is turned over, then a device described as "above" or "over" other devices or structures would then be oriented "below" or "under" the other devices or structures. Accordingly, the exemplary term "above" can encompass both an "above" and "below" orientation. The devices can also be oriented in other ways (rotated 90 degrees or at other orientations) and the spatial relative descriptors used herein interpreted accordingly.

[0047] It should be noted that for the surface of each layer of the multilayer thin film, it can be understood as the surface of the layer of the multilayer thin film in contact with the adjacent layer of the multilayer thin film, or the surface perpendicular to the thickness direction, wherein the thickness direction can be understood as the direction of the multilayer thin film being stacked in sequence.

[0048] For example, the multilayer thin film preparation method provided by the application embodiment can be as follows Figure 1As shown, it mainly includes the following steps:

[0049] S101: preparing a first material layer.

[0050] S102: stacking a plurality of second material layers on the surface of the first material layer, wherein each second material layer includes a second substrate made of a ferroelectric single crystal material.

[0051] pass Figure 1 The multilayer film preparation method shown in FIG. Figure 2 The multilayer film shown. Figure 2 As shown, the multilayer film includes a first material layer 10 and a plurality of second material layers (21 to 2N), where N is an integer greater than 1. Next, the first material layer 10 and the second material layers 21 to 2N and their preparation processes are described respectively.

[0052] First material layer 10

[0053] In the embodiment of the present application, the first material layer 10 may include a first substrate. The first substrate has high mechanical strength and is therefore capable of supporting the second material layers 21 to 2N. In one possible implementation, the first material layer 10 may be composed of the first substrate. Alternatively, it can be understood that the first substrate serves as the first material layer 10 and supports the second material layers 21 to 2N. In this case, when preparing the first material layer, the first substrate may be pre-treated, such as by cleaning and annealing, and then the pre-treated first substrate may be used as the first material layer 10.

[0054] It should be noted that the embodiments of the present application do not impose any restrictions on the specific material of the first substrate. When preparing the first material layer, the material of the first substrate can be flexibly selected according to the application scenario of the multilayer film. Generally speaking, the first substrate can be made of materials such as silicon and germanium.

[0055] In another possible implementation, other thin film layers may be prepared on the first substrate to obtain the first material layer 10. For example, Figure 3a As shown, the first material layer 10 may include a first substrate 101 and a first intermediate layer 102 disposed on the surface of the first substrate 101. When preparing the first material layer 10, the first intermediate layer 102 may be formed on the surface of the first substrate 101 to obtain the first material layer 10. Specifically, the first intermediate layer 102 may be formed on the surface of the first substrate 101 by a deposition or growth process, or may be formed on the surface of the first substrate 101 by a bonding process, and this embodiment of the present application does not impose any particular limitation thereto.

[0056] The function of the first intermediate layer 102 can be flexibly designed according to application scenarios. For example, the first intermediate layer 102 can be a sacrificial layer, a buffer layer, a contact layer, and the like. In this embodiment of the present application, the first intermediate layer 102 can be a single-layer structure or a multi-layer structure. For example, as shown in FIG. 1, the first intermediate layer 102 can include i first intermediate sub-layers (1021 to 102i), i being an integer greater than or equal to 1. The different first intermediate sub-layers can have the same or different physical parameters such as material, thickness, and crystal structure. When the first intermediate layer 102 is prepared, the first intermediate sub-layer 1021 can be prepared layer by layer to the first intermediate sub-layer 102i to obtain the first intermediate layer 102. Figure 3b

[0057] In this embodiment of the present application, the plurality of second material layers 21 to 2N can be stacked on the surface of the first material layer 10 by a bonding process. That is, the second material layer 21 needs to be bonded on the surface of the first material layer 10. However, some thin film materials cannot be directly used in the bonding process. Therefore, the first bonding layer can be prepared in the first material layer 10 to facilitate the bonding of the second material layer 21.

[0058] For example, the first bonding layer 103 can include one or more of silicon dioxide, polysilicon, silicon nitride, copper, zirconium, gold-tin alloy, benzocyclobutene resin-based thermosetting polymer or ultraviolet curing polymer, spin-on polymer (such as polyarylether), methylsilsesquioxane, hydrogen silsesquioxane epoxy, gaseous deposition polymer parylene-N, and the like.

[0059] In one possible implementation, as shown in FIG. 1, the first material layer 10 can include a first substrate 101, a first intermediate layer 102 disposed on the surface of the first substrate 101, and a first bonding layer 103 disposed on the surface of the first intermediate layer 102. When the first material layer 10 is prepared, the first intermediate layer 102 can be prepared on the surface of the first substrate 101, and then the first bonding layer 103 can be prepared on the surface of the first intermediate layer 102 away from the first substrate 101, thereby obtaining the first material layer 10. Specifically, the first bonding layer 103 can be prepared on the surface of the first intermediate layer 102 by a deposition or growth process, or the first bonding layer 103 can be prepared on the surface of the first intermediate layer 102 by a bonding process. This embodiment of the present application does not limit the same. Figure 3c It should be noted that in this embodiment of the present application, the first bonding layer 103 can be a single-layer structure or a multi-layer structure. For example, as shown in FIG. 1, the first bonding layer 103 can include j first bonding sub-layers (1031 to 103j), j being an integer greater than or equal to 1. The different first bonding sub-layers can have the same or different physical parameters such as material, thickness, and crystal structure. When the first bonding layer 103 is prepared, the first bonding sub-layer 1031 can be prepared layer by layer to the first bonding sub-layer 103j to obtain the first bonding layer 103.

[0060] Figure 3d ​​As shown, the first bonding layer 103 can include j first bonding sub-layers (1031 to 103j), j being an integer greater than or equal to 1, and the different first bonding sub-layers can have the same or different material, thickness, crystal structure, and other physical parameters. In preparing the first bonding layer 103, the first bonding sub-layers 1031 to 103j can be prepared layer by layer to obtain the first bonding layer 103.

[0061] It can be understood that, in another possible implementation, the first bonding layer 103 can be prepared on the surface of the first substrate 101 without preparing the first intermediate layer 102 in the first material layer 10, to obtain the first material layer 10 as shown. Figure 3e The specific preparation process is not repeated here.

[0062] The second material layers 21 to 2N

[0063] Taking the second material layer 21 (the other second material layers are similar) as an example, the second material layer 21 can include a second substrate, which can be composed of a ferroelectric single crystal material. Specifically, the second substrate can be composed of an intrinsic (undoped) ferroelectric single crystal material, or can be composed of a doped ferroelectric single crystal material, and the present application does not make many limitations on this.

[0064] At present, the preparation process of the ferroelectric single crystal material wafer is relatively mature, so the second substrate in the present application can be obtained on the basis of the ferroelectric single crystal material wafer, that is, the second substrate in the present application can be understood as part or all of the ferroelectric single crystal material wafer.

[0065] For example, the ferroelectric single crystal material in the present application can be any one of lithium niobate, black lithium niobate, doped lithium niobate, lithium tantalate, black lithium tantalate, doped lithium tantalate, bismuth ferrite, barium titanate, barium strontium titanate, strontium titanate, etc., and the present application does not list them one by one.

[0066] It should be pointed out that the second substrates in different second material layers in the present application can be composed of the same or different ferroelectric single crystal materials, and the present application does not make many limitations on this

[0067] In a possible implementation, the second material layer 21 can be composed of the second substrate, which can also be understood as the second substrate as the second material layer 21, that is, the second substrate is bonded on the surface of the first material layer 10. In this case, when the first material layer 10 is prepared, the second substrate can be cleaned, annealed, and other pretreated, and then the pretreated second substrate can be used as the second material layer 21.

[0068] In another possible implementation, other thin film layers may be prepared on the second substrate to obtain the second material layer 21. For example, Figure 4a As shown, the second material layer 21 may include a second substrate 211 and a second intermediate layer 212 disposed on the surface of the second substrate 211. Therefore, when preparing the second material layer 21, the second intermediate layer 212 may be formed on the surface of the second substrate 211 to obtain the second material layer 21. Specifically, the second intermediate layer 212 may be formed on the surface of the second substrate 211 by a deposition or growth process, or may be formed on the surface of the second substrate 211 by a bonding process, and this embodiment of the present application does not impose any particular restrictions on this.

[0069] Similar to the first intermediate layer 102, the second intermediate layer 212 can be a single layer structure or a multi-layer structure, such as Figure 4b The second intermediate layer 212 includes second intermediate sub-layers 2121 to 212k stacked in layers. The specific implementation can refer to the first intermediate layer 102 and will not be described in detail.

[0070] Similar to the first intermediate layer 102, the second intermediate layer 212 may also include a second bonding layer. Figure 4c As shown, the second material layer 21 may include a second substrate 211, a second intermediate layer 212 disposed on the surface of the second substrate 211, and a second bonding layer 213 disposed on the surface of the second intermediate layer 212. When preparing the second material layer 21, the second intermediate layer 212 may be first prepared on the surface of the second substrate 211, and then the second bonding layer 213 may be prepared on the surface of the second intermediate layer 212 away from the second substrate 211, thereby obtaining the second material layer 21. Specifically, the second bonding layer 213 may be prepared on the surface of the second intermediate layer 212 by a deposition or growth process, or by a bonding process, and this embodiment of the present application does not impose any particular restrictions on this.

[0071] Similar to the first bonding layer 103, the second bonding layer 213 can be a single-layer structure or a multi-layer structure. Figure 4d As shown, the second bonding layer 213 may include m first bonding sub-layers (2131 to 213m), where m is an integer greater than or equal to 1. For specific implementation, reference may be made to the first bonding layer 103, which will not be described in detail in the embodiment of the present application.

[0072] In another possible implementation, without preparing the second intermediate layer 212 in the second material layer 21, the second bonding layer 213 can also be prepared on the surface of the second substrate 211 to obtain the following: Figure 4e The specific preparation process of the second material layer 21 is not described in detail.

[0073] After obtaining the first material layer 10 and the second material layers 21 to 2N, S102 can be continued to stack multiple second material layers on the surface of the first material layer. This process mainly includes setting the second material layer 21 on the surface of the first material layer 10, setting the second material layer 22 on the surface of the second material layer 21 away from the first material layer 10, and so on, until the second material layer 2N is set on the second material layer 2(N-1)( Figure 2 The surface of the substrate 10 is not shown in FIG.

[0074] Next, the arrangement of the second material layer 21 on the surface of the first material layer 10 will be further described.

[0075] Generally speaking, the second material layer 21 can be disposed on the surface of the first material layer 10 by a bonding process or the like. It should be noted that, when the first material layer 10 only includes the first substrate 101, the second material layer 21 can be disposed on any surface of the first substrate 101. When the first material layer 10 includes the first intermediate layer 102, as shown in FIG. Figure 3a As shown, the second material layer 21 can be arranged on the surface of the first intermediate layer 102 away from the first substrate 101. In the case where the first material layer 101 further includes a first bonding layer 103, as shown in FIG. Figure 3c and Figure 3e As shown, the second material layer 21 may be disposed on a surface of the first bonding layer 103 away from the first substrate 101 .

[0076] In the embodiment of the present application, the surface of the second material layer 21 in contact with the first material layer 10 can be referred to as the first surface of the second material layer 21. Specifically, when the second material layer 21 only includes the second substrate 211, the first surface can be any surface of the second substrate 211. When the second material layer 21 also includes the second intermediate layer 211, such as Figure 4a As shown, the first surface may be the surface of the second intermediate layer 211 away from the first substrate, that is, the second intermediate layer 211 is in contact with the first material layer 10. In the case where the second material layer 21 further includes a second bonding layer 213, as shown in FIG. Figure 4c and Figure 4e As shown, the first surface may be a surface of the second bonding layer 213 away from the first substrate, that is, the second bonding layer 213 is in contact with the first material layer 10 .

[0077] Figure 5 The intermediate structure obtained after the first material layer 10 and the second material layer 21 are fixed is shown as an example. Figure 5 As shown, the first bonding layer 103 in the first material layer 10 is bonded to the second bonding layer 213 in the second material layer 21, thereby completing the fixation between the first material layer 10 and the second material layer 21.Figure 5 The second material layer 22 can be continuously stacked on the basis of the intermediate structure shown.

[0078] Next, the process of arranging the second material layer 21 on the surface of the first material layer 10 is further exemplarily described by taking the first material layer 10 as an example to obtain the intermediate structure shown. Figure 6 As shown, the process mainly includes the following steps: Figure 7 Figure 6

[0079] S601: Preprocessing the first substrate 101. For example, cleaning, annealing, etc. The embodiments of the present application do not make too many restrictions on this.

[0080] S602: Preparing the first intermediate sublayer 1021 to 102i on the surface of the first substrate 101 in sequence to obtain the first intermediate layer 102.

[0081] S603: Continuously preparing the first bonding sublayer 1031 to 103j on the surface of the first intermediate sublayer 102i in sequence to obtain the first bonding layer 103.

[0082] S604: Preprocessing the second substrate 211. For example, cleaning, annealing, etc. The embodiments of the present application do not make too many restrictions on this.

[0083] S605: Preparing the second intermediate sublayer 2121 to 212k on the surface of the second substrate 211 in sequence to obtain the second intermediate layer 212.

[0084] S606: Continuously preparing the second bonding sublayer 2131 to 213m on the surface of the second intermediate sublayer 202k in sequence to obtain the second bonding layer 213.

[0085] It should be noted that the embodiments of the present application do not strictly limit the order of preparing the first material layer 10 and the second material layer 21, that is, S601 to S603 can be executed first, and then S604 to S606 can be executed; or S604 to S606 can be executed first, and then S601 to S603 can be executed; or the process of S601 to S603 and the process of S604 to S606 can be executed in parallel.

[0086] S607: Planarizing the surface of the first bonding sublayer 103j away from the first substrate 101, and planarizing the surface of the second bonding sublayer 213m away from the second substrate 211. The planarization processing can eliminate the surface defects of the first substrate 101 and the second substrate 211, which is beneficial to improve the subsequent bonding effect.

[0087] S608: Bonding the surface of the first bonding sublayer 103j away from the first substrate 101 with the surface of the second bonding sublayer 213m away from the second substrate 211, thereby obtaining​​Figure 7 the intermediate structure shown.

[0088] In a possible implementation, the thinning of the second substrate 211 can be continued in S609.

[0089] S610: planarization processing is performed on the surface of the second substrate 211 after the thinning.

[0090] After the intermediate structure shown in Figure 5 or Figure 7 the second material layer 22 can be disposed. Specifically, the first surface of the second material layer 22 can be disposed on the surface of the second substrate 211 away from the first substrate 101. The first surface of the second material layer 22 is similar to the second material layer 21, and thus will not be described again. That is, the first surface of the second material layer 21 to 2N is disposed towards the first material layer 10.

[0091] In a possible implementation, before the second material layer 22 is disposed, the second substrate 211 in the second material layer 21 can be thinned first, so that the thickness of the second substrate can reach a target thickness. Generally, the second substrate 211 can be thinned to a thickness range of 10-100 μm.

[0092] After the thinning, the surface of the second material layer 21 away from the first material layer 10 can be subjected to planarization processing, and the second material layer 22 can be disposed on the surface after the planarization processing, so as to reduce defects of the multi-layer thin film and improve the quality of the multi-layer thin film.

[0093] It can be understood that the second material layer 22 and the second material layer 21 can be further separated by a third intermediate layer, so as to optimize the structure of the multi-layer thin film or realize a specific function of the multi-layer thin film. That is, the third intermediate layer can be prepared on the surface of the second substrate 211 away from the first substrate 101, and the second material layer 22 can be disposed on the surface of the third intermediate layer away from the second substrate 211.

[0094] In a possible implementation, as shown in Figure 8 the third material layer 31 is disposed on the surface of the second material layer 21. The third material layer 31 can only include the third intermediate layer 311, or only include the third bonding layer 312. It can be understood that the third material layer 31 can include both the third intermediate layer 311 and the third bonding layer 312. In this case, when the second material layer 22 is disposed on the surface of the second material layer 21, the third intermediate layer 311 can be prepared on the surface of the second material layer 21 first, then the third bonding layer 312 can be prepared on the surface of the third intermediate layer away from the second material layer 21, and then the second material layer 22 can be disposed on the surface of the third bonding layer away from the second material layer 21.

[0095] It can be understood that the third intermediate layer 311 can be a single-layer structure or a multi-layer structure, and the specific implementation can refer to the first intermediate layer 102, and details are not repeated. The third bonding layer 312 can be a single-layer structure or a multi-layer structure, and the specific implementation can refer to the first bonding layer 103, and details are not repeated. The setting process of the second material layers 23 to 2N can refer to the second material layer 22, and details are not repeated.

[0096] The multi-layer thin film preparation method provided by the embodiment of the present application is advantageous to expand the application range of the multi-layer thin film preparation process. Specifically, the embodiment of the present application stacks a plurality of second material layers on the surface of the first material layer, and each second material layer includes a second substrate. Therefore, the obtained multi-layer thin film can include a plurality of thin film layers composed of ferroelectric single crystal material, and the second substrate is also composed of ferroelectric single crystal material, thereby realizing the preparation of a plurality of thin film layers composed of ferroelectric single crystal material in the multi-layer thin film.

[0097] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the scope of the present application. Thus, if these modifications and variations of the present application belong to the scope of the claims of the present application and the equivalent technology thereof, the present application also intends to include these modifications and variations.

Claims

1. A method for preparing a multilayer film, characterized in that: include: preparing a first material layer, wherein the first material layer comprises, from bottom to top, a first substrate, a first intermediate layer, and a first bonding layer; A plurality of second material layers are stacked on the surface of the first material layer, wherein each second material layer includes a second substrate, and the second substrate is composed of a ferroelectric single crystal material; Each second material layer includes a second bonding layer, a second intermediate layer and the second substrate from bottom to top, each intermediate layer includes at least one of a sacrificial layer, a buffer layer and a contact layer, and each bonding layer is used to bond to other adjacent layers.

2. The method according to claim 1, characterized in that Before laminating a plurality of second material layers on the surface of the first material layer, the method further comprises: For each second material layer, preparing a second intermediate layer on the surface of the second substrate; A second bonding layer is prepared on a surface of the second intermediate layer away from the second substrate to obtain the second material layer.

3. The method according to claim 2, characterized in that The plurality of second material layers are stacked on the surface of the first material layer, comprising: The multiple second material layers are stacked on the surface of the first material layer, wherein the first surfaces of the multiple second material layers are all arranged toward the first material layer, and the first surface of the second material layer is the surface of the second material layer away from the second substrate.

4. The method according to any one of claims 1 to 3, characterized in that Preparing a first material layer, comprising: preparing a first intermediate layer on the surface of the first substrate; A first bonding layer is prepared on a surface of the first intermediate layer away from the first substrate to obtain the first material layer.

5. The method according to claim 4, characterized in that The plurality of second material layers are stacked on the surface of the first material layer, comprising: The plurality of second material layers are stacked on a surface of the first material layer away from the first substrate.

6. The method according to any one of claims 1 to 5, characterized in that The plurality of second material layers are stacked on the surface of the first material layer, comprising: Disposing a second material layer on the surface of the first material layer, and preparing a third intermediate layer on the surface of the disposed second material layer; Another second material layer is disposed on a surface of the third intermediate layer away from the disposed second material layer until the plurality of second material layers are completely disposed.

7. The method according to any one of claims 1 to 6, characterized in that The plurality of second material layers are stacked on the surface of the first material layer, comprising: Disposing a second material layer on the surface of the first material layer; preparing a third intermediate layer on the surface of the disposed second material layer; preparing a third bonding layer on a surface of the third intermediate layer away from the disposed second material layer; Another second material layer is disposed on a surface of the third bonding layer away from the disposed second material layer until the plurality of second material layers are completely disposed.

8. The method according to claim 6 or 7, characterized in that Before preparing the third intermediate layer on the surface of the disposed second material layer, the method further comprises: Thinning the second surface of the disposed second material layer so that the second substrate in the disposed second material layer reaches a target thickness; performing a planarization process on the second surface of the disposed second material layer; The second surface of the second material layer is a surface of the second material layer where the second substrate is located.

9. The method according to any one of claims 1 to 8, characterized in that The ferroelectric single crystal material includes: lithium niobate, blackened lithium niobate, doped lithium niobate, lithium tantalate, blackened lithium tantalate, doped lithium tantalate, bismuth ferrite, barium titanate, barium strontium titanate or strontium titanate.

10. A multilayer film, characterized in that include: a plurality of second material layers and a first material layer; The plurality of second material layers are stacked on the surface of the first material layer, and the first material layer includes, from bottom to top, a first substrate, a first intermediate layer, and a first bonding layer; Each of the second material layers includes a second substrate, the second substrate is made of a ferroelectric single crystal material, and each of the second material layers includes, from bottom to top, a second bonding layer, a second intermediate layer and the second substrate; Each intermediate layer includes at least one of a sacrificial layer, a buffer layer, and a contact layer, and each bonding layer is used for bonding to other adjacent layers.

11. The multilayer film according to claim 10, wherein The second intermediate layer is arranged on a surface of the second substrate, and the second bonding layer is arranged on a surface of the second intermediate layer away from the second substrate.

12. The multilayer film according to claim 10 or 11, characterized in that The first surfaces of the plurality of second material layers are all arranged toward the first material layer, and the first surface of the second material layer is a surface of the second material layer away from the second substrate.

13. The multilayer film according to any one of claims 10 to 12, characterized in that The first intermediate layer is arranged on a surface of the first substrate, and the first bonding layer is arranged on a surface of the first intermediate layer away from the first substrate.

14. The multilayer film according to claim 13, wherein The plurality of second material layers are stacked and arranged on a surface of the first material layer away from the first substrate.

15. The multilayer film according to any one of claims 10 to 14, characterized in that A third intermediate layer is further provided between adjacent second material layers.

16. The multilayer film according to any one of claims 10 to 15, characterized in that A third intermediate layer and a third bonding layer are stacked between adjacent second material layers.

17. The multilayer film according to any one of claims 10 to 16, characterized in that The thickness of the second substrate is 10-100 μm.

18. The multilayer film according to any one of claims 10 to 17, characterized in that The ferroelectric single crystal material includes: lithium niobate, blackened lithium niobate, doped lithium niobate, lithium tantalate, blackened lithium tantalate, doped lithium tantalate, bismuth ferrite, barium titanate, barium strontium titanate or strontium titanate.

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