An ultra-smooth sheet and a method for making the same

Abstract

The application discloses an ultra-smooth sheet, relates to the field of ultra-smoothness, and comprises a substrate, wherein the substrate comprises a single-crystal two-dimensional material layer with a preset number of layers, and the preset number of layers is not more than ten; and an island cover is fixedly connected to the upper surface of the substrate. The ultra-smooth sheet comprises the substrate and the island cover, the island cover is fixedly connected to the substrate, the substrate comprises the single-crystal two-dimensional material layer, the thickness of the substrate is very small, the number of layers of the single-crystal two-dimensional material layer is not more than ten, and the substrate has excellent ultra-smoothness, i.e., small friction and no wear performance, so that the ultra-smooth sheet is an ultra-smooth structure based on the substrate with the ultra-smoothness, the material of the island cover can be any material, the material of the single-crystal two-dimensional material layer can also be any two-dimensional material, and the ultra-smooth sheet has a simple structure and can be applied to mass processing and production detection. In addition, the application further provides an ultra-smooth sheet manufacturing method with the above advantages.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of super-slip, in particular to a super-slip sheet and a manufacturing method thereof. BACKGROUND

[0002] At present, the most common micron-level super-slip sheet is a micron-level graphite island prepared on the basis of highly oriented pyrolytic graphite (HOPG), and the upper and lower super-slip sheets are separated by a tungsten needle through shear stress. Due to the reasons of preparation principle and material properties, such super-slip sheet is limited to only one material of graphite, and only one super-slip state information of the super-slip sheet can be detected at a time, which is not suitable for industrial mass processing and production.

[0003] Therefore, how to solve the above technical problems should be the focus of the person skilled in the art. SUMMARY

[0004] The application aims to provide a super-slip sheet and a manufacturing method thereof, so as to provide a super-slip sheet based on any single-crystal two-dimensional material as a substrate, and the structure is simple.

[0005] To solve the above technical problems, the application provides a super-slip sheet, which comprises:

[0006] A substrate, wherein the substrate comprises a preset number of single-crystal two-dimensional material layers, and the preset number is not more than ten;

[0007] An island cover fixedly connected to the upper surface of the substrate.

[0008] Optionally, the island cover is made of a conductive material, and the substrate and the island cover can be electrically connected.

[0009] Optionally, the island cover comprises at least one conductive layer.

[0010] Optionally, when the conductive layer is a metal layer, the super-slip sheet further comprises:

[0011] A conductive connection layer arranged between the substrate and the island cover.

[0012] Optionally, the island cover comprises two metal layers.

[0013] Optionally, when the number of the conductive layers is two or more, in the direction away from the substrate, the size of the next conductive layer is less than or equal to the size of the previous conductive layer.

[0014] Optionally, the thickness of the island cover is more than 100 nm.

[0015] Optionally, the island cover is provided with a transfer part away from the surface of the substrate to facilitate the transfer of the super-smooth sheet.

[0016] The application also provides a method for manufacturing a super-smooth sheet, comprising:

[0017] obtaining an island cover, the upper surface or / and the lower surface of the island cover being an atomically flat surface; transferring or growing a preset number of monolayer two-dimensional material layers on any of the atomically flat surfaces as a substrate to obtain a super-smooth sheet, wherein the preset number of layers is not more than ten layers;

[0018] Alternatively,

[0019] using a mechanical exfoliation method to prepare a preset number of monolayer two-dimensional material layers on a substrate as a substrate, wherein the preset number of layers is not more than ten layers;

[0020] forming an island cover on the substrate to obtain a super-smooth sheet on the substrate, and separating the super-smooth sheet from the substrate.

[0021] Optionally, forming an island cover on the substrate comprises:

[0022] coating photoresist on the substrate, the photoresist covering the substrate inside;

[0023] exposing and developing the photoresist corresponding to the substrate to obtain a treated substrate;

[0024] depositing an island cover layer on the treated substrate, and peeling off the photoresist and the island cover layer on the photoresist to form the island cover on the substrate.

[0025] Optionally, when the island cover comprises at least one metal layer, after the step of using a mechanical exfoliation method to prepare a preset number of monolayer two-dimensional material layers on a substrate as a substrate, the method further comprises:

[0026] preparing a conductive connection layer on the substrate;

[0027] Correspondingly, the step of coating photoresist on the substrate, the photoresist covering the substrate inside comprises:

[0028] coating photoresist on the substrate, the photoresist covering the substrate and the metal connection layer inside.

[0029] Optionally, when the island cover comprises at least two metal layers, the step of depositing an island cover layer on the treated substrate, and peeling off the photoresist and the island cover layer on the photoresist to form the island cover on the substrate comprises:

[0030] Step S11: forming a metal layer on the treated substrate;

[0031] Step S12: stripping the photoresist and the metal layer on the photoresist;

[0032] Step S13: coating photoresist on the processed substrate again, and the photoresist coated again covers the substrate and the metal layer inside;

[0033] Step S14: exposing and developing the photoresist coated again corresponding to the metal layer to obtain a new processed substrate, and entering step S11 until the number of layers of the metal layer reaches a preset value.

[0034] Optionally, separating the super-smooth sheet from the substrate comprises:

[0035] pressing the super-smooth sheet in the vertical direction by using a transfer head;

[0036] lifting the super-smooth sheet and transferring the super-smooth sheet to a new substrate.

[0037] The super-smooth sheet provided in the present application comprises a substrate, wherein the substrate comprises a preset number of monocrystalline two-dimensional material layers, and the preset number of layers is not more than ten; and an island cover fixedly connected to the upper surface of the substrate.

[0038] It can be seen that the super-smooth sheet in the present application comprises a substrate and an island cover, the island cover is fixedly connected to the substrate, the substrate comprises a monocrystalline two-dimensional material layer, the thickness of the substrate is very thin, the number of layers of the monocrystalline two-dimensional material layer is not more than ten, and the substrate has excellent super-smooth performance, small friction and no wear performance, and the super-smooth sheet in the present application is a super-smooth structure based on a substrate with super-smooth performance, the material of the island cover can be any material, and the material of the monocrystalline two-dimensional material layer can also be any two-dimensional material, and the super-smooth sheet in the present application has a simple structure and can be applied to mass processing and production detection.

[0039] In addition, the present application also provides a super-smooth sheet manufacturing method with the above advantages. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0041] Figure 1 A structural schematic diagram of a super-smooth sheet provided by an embodiment of the present application;

[0042] Figure 2 A structural schematic diagram of another super-smooth sheet provided by an embodiment of the present application;

[0043] Figure 3 A top view of a super-slippery sheet according to an embodiment of the present application;

[0044] Figure 4 A flow chart of a method for manufacturing a super-slippery sheet according to an embodiment of the present application;

[0045] Figure 5 A flow chart of another method for manufacturing a super-slippery sheet according to an embodiment of the present application;

[0046] Figure 6 and Figures 10 to 13 A flow chart of a method for manufacturing a super-slippery sheet according to an embodiment of the present application;

[0047] Figure 7 An optical microscope image of graphene on a silicon substrate with silicon dioxide according to an embodiment of the present application;

[0048] Figure 8 Raman spectra of graphene with different layers according to an embodiment of the present application;

[0049] Figure 9 AFM topography of graphene with different layers according to an embodiment of the present application;

[0050] Figure 14 A schematic diagram of etching a large-size super-slippery sheet to obtain a small-size super-slippery sheet according to an embodiment of the present application;

[0051] Figures 15 to 17 A schematic diagram of transferring a super-slippery sheet according to an embodiment of the present application;

[0052] Figures 18 to 23 A flow chart of a process for preparing a super-slippery sheet including two metal layers according to an embodiment of the present application;

[0053] Figure 24 A super-slippery property diagram of a traditional graphite island on 5 layers or less of graphene;

[0054] In the diagram, 1. substrate, 2. island cover, 21. metal layer, 22. transfer part, 3. substrate, 4. photoresist, 5. first layer of metal, 6. second layer of metal, 2'. island cover layer. DETAILED DESCRIPTION

[0055] In order to make the person skilled in the art better understand the present application, the present application will be further described in detail below in combination with the drawings and specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by the person skilled in the art without making creative efforts fall within the scope of protection of the present application.

[0056] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, it will be apparent to one skilled in the art that the present application can be practiced without the specific details set forth in this description. In other instances, well-known methods, procedures, components, and circuits have not been described in detail as not to unnecessarily obscure aspects of the present application.

[0057] As described in the background section, the most common micron-scale super-slippery sheet is micron-scale graphite island. Due to the reasons of preparation principle, material properties, etc., such super-slippery sheet is limited to only one material of graphite, and it can only detect the super-slippery state information of one super-slippery sheet at a time, which is not suitable for industrial mass processing and production.

[0058] Therefore, the present application provides a super-slippery sheet, which comprises: Figure 1 , comprising:

[0059] a substrate 1, wherein the substrate 1 comprises a preset number of single-crystal two-dimensional material layers, and the preset number is not more than ten;

[0060] an island cover 2 fixedly connected to the upper surface of the substrate 1.

[0061] Figure 1 The island cover 2 is shown on the upper surface of the substrate 1.

[0062] The number of single-crystal two-dimensional material layers in the substrate 1 can be one, two, three, four, or ten, and the specific number can be set by the user. The single-crystal two-dimensional material layer with a preset number of layers is different from the single-crystal two-dimensional material layer with a number of layers more than the preset number. The single-crystal two-dimensional material layer with a preset number of layers has special physical properties and can still maintain excellent super-slippery performance on various substrates 1, with small friction and excellent wear resistance.

[0063] The size of the single-crystal two-dimensional material layer can be determined as appropriate, and the present application does not make specific limitations. Optionally, the size of the single-crystal two-dimensional material layer is greater than 200 μm 2 . Similarly, the shape of the single-crystal two-dimensional material layer is not limited in the present application. For example, the shape of the single-crystal two-dimensional material layer can be circular, square, rectangular, polygonal, or any irregular shape.

[0064] The material of the single-crystal two-dimensional material layer can be a single-crystal two-dimensional conductor material, a single-crystal two-dimensional semiconductor material, or a single-crystal two-dimensional insulator material, all of which are within the scope of the present application. The single-crystal two-dimensional conductor material includes but is not limited to graphite, graphene, niobium disulfide, and tantalum disulfide. The single-crystal two-dimensional semiconductor material includes but is not limited to molybdenum disulfide, tungsten diselenide, tungsten disulfide, and black phosphorus. The single-crystal two-dimensional insulator material includes but is not limited to hexagonal boron nitride and mica.

[0065] It should be noted that the material of the island cover 2 in the present application is not limited, and is determined according to the situation. For example, the material of the island cover 2 can be a conductor, an insulator, or a semiconductor. Similarly, the shape of the island cover 2 can also be determined according to the situation, for example, the shape of the island cover 2 can be rectangular, oval, square, or any irregular shape. Further, the thickness of the island cover 2 in the present application is not limited and can be set by itself. Preferably, in order to maintain the flatness of the two-dimensional single crystal material layer and avoid wrinkles, the thickness of the island cover 2 is greater than or equal to 100 nm.

[0066] The super-smooth sheet in the present application includes a substrate 1 and an island cover 2, the island cover 2 is fixedly connected with the substrate 1, the substrate 1 includes a single crystal two-dimensional material layer, the thickness of the substrate 1 is very thin, the number of layers of the single crystal two-dimensional material layer is not more than ten, and the substrate 1 has excellent super-smooth performance, small friction and no wear performance, so that the super-smooth sheet in the present application is a super-smooth structure based on the substrate 1 with super-smooth performance, the material of the island cover 2 can be any material, and the material of the single crystal two-dimensional material layer can also be any two-dimensional material. Further, the super-smooth sheet structure in the present application is simple and can be applied to mass processing and production testing.

[0067] On the basis of the above-mentioned embodiments, in an embodiment of the present application, the island cover is made of conductive material, and the substrate 1 and the island cover 2 can be electrically connected, so that the super-smooth sheet in the present application can be used in electrical applications, thereby widening the application range of the super-smooth sheet.

[0068] At this time, the materials of the single crystal two-dimensional material and the island cover 2 are both conductive materials, and the single crystal two-dimensional conductor material can be graphite, graphene, niobium disulfide, or tantalum disulfide.

[0069] The island cover 2 includes at least one conductive layer, for example, the number of layers of the conductive layer can be one, two, three, etc., and the material of the island cover 2 can be palladium, platinum, or other conductive materials. When the island cover 2 includes a multi-layer structure, the materials of each layer can be the same or different, which are all within the protection scope of the present application.

[0070] When the number of layers of the conductive layer is two or more, in order to facilitate the preparation of the super-smooth sheet, the size of the next conductive layer is less than or equal to the size of the previous conductive layer in the direction away from the substrate 1. For example, in order to facilitate the description, in the direction away from the substrate 1, the multi-layer conductive layer is respectively referred to as a first conductive layer, a second conductive layer, a third conductive layer, and so on. Therefore, the size of the second conductive layer is less than or equal to the size of the first conductive layer, the size of the third conductive layer is less than or equal to the size of the second conductive layer, and so on.

[0071] The number of layers of the metal layer in the island cover 2 can be one, two, three, etc. When the island cover 2 includes two metal layers 21, the structural schematic diagram of the super-smooth sheet is shown in FIG. 2B. Figure 2The thickness of the metal layer 21 close to the substrate 1 can be 200 nm, and the size can be 6 μm x 6 μm. The thickness of the metal layer 21 away from the substrate 1 can be 100 nm, and the size can be 3 μm x 3 μm.

[0072] In an embodiment of the present application, when the conductive layer is a metal layer, the super-smooth sheet further comprises:

[0073] A conductive connecting layer is arranged between the substrate 1 and the island cover 2.

[0074] The conductive connecting layer can be made of chromium or titanium or other materials with good connecting stability.

[0075] When the island cover 2 is a metal layer, the metal layer has poor connecting stability with the special monocrystalline two-dimensional material layer (for example, graphene). The conductive connecting layer can enhance the connecting stability between the island cover 2 and the substrate 1, thereby enhancing the structural stability of the super-smooth sheet.

[0076] On the basis of any of the above embodiments, in an embodiment of the present application, the island cover 2 is provided with a transfer part away from the surface of the substrate 1, so as to facilitate the transfer of the super-smooth sheet. The transfer part can increase the friction of the surface of the island cover 2, thereby facilitating the use and transfer of the super-smooth sheet.

[0077] The transfer part includes but is not limited to a groove or a protrusion. The shape of the groove or the protrusion can be circular, square, annular, threaded, etc., which is not limited in the present application.

[0078] When the transfer part 22 is an annular groove, the plan view of the super-smooth sheet is as shown in Figure 3 .

[0079] The present application also provides a method for manufacturing a super-smooth sheet, which is described in detail in Figure 4 . The method comprises the following steps:

[0080] Step S101: obtaining an island cover, wherein the upper surface or / and the lower surface of the island cover is an atomically flat surface.

[0081] The island cover in this step can be directly obtained from a finished island cover or manufactured by processing and molding. The atomically flat surface generally refers to a surface with a roughness of less than 1 nm.

[0082] Step S102: transferring or growing a monocrystalline two-dimensional material layer with a preset number of layers on any of the atomically flat surfaces as a substrate to obtain a super-smooth sheet, wherein the preset number of layers is not more than ten.

[0083] When the upper surface of the island cover is an atomically flat surface, a monocrystalline two-dimensional material layer is transferred or grown on the upper surface of the island cover; when the lower surface of the island cover is an atomically flat surface, a monocrystalline two-dimensional material layer is transferred or grown on the lower surface of the island cover; when the upper surface and the lower surface of the island cover are both atomically flat surfaces, a monocrystalline two-dimensional material layer is grown on the upper surface or the lower surface of the island cover. The growth method includes but is not limited to chemical vapor deposition and epitaxial growth, and the transfer method can use mechanical exfoliation.

[0084] Growth of a monocrystalline two-dimensional material layer with a preset number of layers on the atomically flat surface of the island cover can form a super-smooth sheet with a large size, and then the friction force of the super-smooth sheet is measured by an atomic force microscope, and the super-smooth sheet with a friction force lower than a certain threshold value is selected.

[0085] The application also provides another method for manufacturing a super-smooth sheet, please refer to Figure 5 , the method comprises:

[0086] Step S201: preparing a monocrystalline two-dimensional material layer with a preset number of layers as a substrate on a substrate by mechanical exfoliation, wherein the preset number of layers is not more than ten.

[0087] This step please refer to Figure 6 , the substrate 1 is located on the upper surface of the substrate 3. The material of the monocrystalline two-dimensional material layer can be a monocrystalline two-dimensional conductor material, a monocrystalline two-dimensional semiconductor material or a monocrystalline two-dimensional insulator material, all of which are within the protection scope of the application. The monocrystalline two-dimensional conductor material includes but is not limited to graphite, graphene, niobium disulfide and tantalum disulfide, the monocrystalline two-dimensional semiconductor material includes but is not limited to molybdenum disulfide, tungsten diselenide, tungsten disulfide and black phosphorus, and the monocrystalline two-dimensional insulator material includes but is not limited to hexagonal boron nitride and mica.

[0088] This step includes:

[0089] Step S2011: cleaning the substrate.

[0090] The substrate is cleaned with ethanol, isopropanol and deionized water: the solution for soaking the substrate is placed in an ultrasonic cleaning machine, and when ethanol is used as the cleaning solution, it needs to be cleaned for 10 minutes; when isopropanol is used as the cleaning solution, it needs to be cleaned for 10 minutes; when deionized water is used as the cleaning solution, it needs to be cleaned for 15 minutes, and after the new deionized water is replaced, it needs to be cleaned again, and the deionized water is used for a total of 3 times.

[0091] Step S2012: blowing the cleaned substrate dry with dry nitrogen.

[0092] Step S2013: heating the blown dry substrate using a hot stage, the heating temperature is 150℃, and the heating time is 20 minutes.

[0093] Step S2014: The heated substrate is treated with a plasma cleaner, using 99.999% oxygen gas for 20 minutes.

[0094] Step S2015: Use tape 1 to adhere the block-shaped two-dimensional material, then use a new piece of tape 2 to adhere tape 1, reducing the number of layers of the block-shaped two-dimensional material. Repeat the above operation (adhesive tape 3 to tape 2, tape 4 to tape 3, ...) until the color of the block-shaped two-dimensional material on the tape changes. Specifically, when the block-shaped two-dimensional material is graphite, continue until the graphite on the tape turns grayish-white.

[0095] Step S2016: Attach the last piece of tape to the substrate treated by the plasma cleaner and press firmly.

[0096] Step S2017: Place the substrate with the adhesive tape on the hot plate and heat it at a temperature of 150°C for 20 minutes.

[0097] Step S2018: Remove the heated substrate and place it on the experimental table. Peel off the adhesive tape to obtain the mechanically exfoliated substrate. When the blocky two-dimensional material in step S2015 is graphite, this step yields graphene.

[0098] After obtaining the substrate and before forming the island cap, the number of single-crystal two-dimensional material layers, the defect concentration, and the roughness of the single-crystal two-dimensional material layers can be confirmed. Taking silicon dioxide or silicon as the substrate and graphene as the single-crystal two-dimensional material layer as an example, the process can be as follows:

[0099] Step S1: Select the light purple region using the optical microscope equipped with the Raman spectrometer. The optical microscope image is shown below. Figure 7 As shown, Figure 7 (b) is Figure 7 (a) is an enlarged view of the rectangle. In the optical microscopy image, light purple represents silicon dioxide or a silicon substrate, dark purple represents a predetermined number of graphene layers, and light blue and gray represent graphene layers exceeding the predetermined number. It should be noted that the predetermined number of graphene layers is nearly transparent; the light purple indicates that the color of the silicon dioxide or silicon substrate is visible. If the substrate is different, the color of the predetermined number of graphene layers will change depending on the substrate color.

[0100] Step S2: Select regions with a single number of layers, smooth morphology, and no obvious defects. Use Raman spectroscopy to characterize the number of graphene layers. The Raman spectra of graphene with different numbers of layers are shown below. Figure 8 As shown, Figure 8 The horizontal axis represents wavelength, and the vertical axis represents relative intensity. When the ratio of G peak intensity to 2D peak intensity is less than 1, the number of graphene layers is 1; when the ratio is greater than 1, the number of graphene layers is 2 or more. Figure 8The Raman spectra of the four graphene layers (1), (2), (3), and (4) are the Raman spectra of the 1, 2, 3, and 4-layer graphene, respectively.

[0101] Step S3: Characterize the morphology of graphene, including edge height difference and surface roughness, using atomic force microscopy (AFM) to reconfirm the number of layers and roughness of the single-crystal two-dimensional material. The AFM morphology images of 1, 2, 3, and 4 layers of graphene are shown below. Figure 9 As shown in (a), (b), (c), and (d), the graphene samples of each layer have no obvious protrusions in the range of 4×4μm, and the roughness is extremely low, ranging from 200 to 300 pm, which is an atomically smooth surface.

[0102] Step S202: Form an island cover on the substrate to obtain a superslipper located on the substrate, and separate the superslipper from the substrate.

[0103] Optionally, forming an island cover on the substrate includes:

[0104] Step S2021: Coat the substrate with photoresist, the photoresist covering the substrate inside.

[0105] Photoresist 4 can be applied to the substrate surface by spin coating. Please refer to the instructions for this step. Figure 10 The area of ​​photoresist 4 is larger than the area of ​​substrate 1, and it covers substrate 1 (a single-crystal two-dimensional material layer with a preset number of layers) inside.

[0106] Step S2022: Expose and develop the photoresist corresponding to the substrate to obtain the processed substrate.

[0107] Please refer to the following steps. Figure 11 The photoresist 4 is treated with a developer to develop grooves on the photoresist 4 for processing the island cover. The shape of the grooves includes, but is not limited to, circles and squares. The developer needs to expose and remove all the photoresist on the top layer of single-crystal two-dimensional material to ensure that the island cover can be completely bonded to the single-crystal two-dimensional material without the need for adhesives or other materials. At the same time, when the island cover is made of metal, it can have better conductivity.

[0108] Step S2023: Deposit an island cap layer on the processed substrate, and strip the photoresist and the island cap layer located on the photoresist to form the island cap on the substrate.

[0109] Please refer to the following steps. Figure 12 and Figure 13 By applying all of the photoresist 4 and the island cap layer 2' on the photoresist 4, the island cap 2 can be formed on the substrate.

[0110] The material of the island cover can be a conductor, an insulator, or a semiconductor, as appropriate. When an electrical connection is required between the island cover and the substrate, the island cover comprises at least one conductive layer, in which case the material of the island cover can be a metal such as palladium, platinum, or other conductive material. When the island cover comprises only one layer of structure, the island cover can be prepared by a process as described below with reference to Figure 12 and Figure 13 When the island cover comprises two or more layers of structure, this is described below.

[0111] It should be noted that the deposition process for the island cover layer is not limited in the present application and can be selected as appropriate. For example, the deposition process can be magnetron sputtering, evaporation, or the like.

[0112] When a small-size super-smooth sheet is required, a large-size super-smooth sheet can be etched by a reactive ion etching technique to produce multiple small-size super-smooth sheets, as shown in Figure 14 The size of the small-size super-smooth sheet is not specifically limited and can be etched as required. The ion etching can be used to fully expose the single-crystal two-dimensional material layer of the predetermined number of layers, so that the presence of photoresist or other material at the edge is avoided, which can affect the super-smooth properties.

[0113] The super-smooth sheet prepared in the present application comprises a substrate and an island cover, the island cover is fixedly connected to the substrate, the substrate comprises a single-crystal two-dimensional material layer, the substrate is very thin, and the number of layers of the single-crystal two-dimensional material layer is not more than ten, so that the substrate has excellent super-smooth properties, has small friction and no wear performance, and the super-smooth sheet in the present application is a super-smooth structure based on a substrate having super-smooth properties, the material of the island cover can be any material, and the material of the single-crystal two-dimensional material layer can also be any two-dimensional material. The super-smooth sheet structure in the present application is simple and can be applied to mass processing and production testing.

[0114] In addition, compared with the conventional graphite super-smooth sheet which uses a tungsten needle to separate the upper and lower super-smooth sheets by shear stress, first, the size of the upper super-smooth sheet prepared by the conventional method is not fixed, which causes the friction properties and electrical properties of the conventional graphite super-smooth sheet to be inconsistent. However, the height of the substrate and the height of the metal cover in the super-smooth sheet prepared in the present application are fixed, so the properties of the structure are consistent, and the corresponding mechanical and electrical properties are more consistent. Second, the exposed super-smooth surface during the preparation of the conventional super-smooth sheet is not fixed, and the properties such as the morphology and structure are not controllable. However, the method of mechanical exfoliation is used in the present application to prepare a single-crystal two-dimensional material layer of a predetermined number of layers as the bottom super-smooth surface, and a region with a controllable morphology, a uniform structure, and no obvious defects can be selected as the super-smooth surface. Third, the conventional super-smooth sheet is prepared based on highly oriented pyrolytic graphite, and there are multiple grain boundaries on the super-smooth sheet. If the grain boundaries are included in the upper and lower layers separated by shearing, the super-smooth sheet will fail. However, the single-crystal two-dimensional material layer of a predetermined number of layers prepared by the method of mechanical exfoliation in the present application is a single crystal, which can ensure that the substrate prepared has a 100% super-smooth property.

[0115] In another aspect, the self-recovery effect of the single-crystal two-dimensional material does not need to be detected in the present application, and due to the difference in preparation method, the step of verifying whether the dissociation surface is a super-smooth surface through the self-recovery effect is omitted, which can greatly improve the batch transfer capability.

[0116] On the basis of the above-mentioned embodiments, in an embodiment of the present application, when the island cover comprises at least two metal layers, the island cover layer is deposited on the processed substrate, and the photoresist and the island cover layer on the photoresist are peeled off to form the island cover on the substrate, which comprises:

[0117] Step S11: forming a metal layer on the processed substrate;

[0118] Step S12: peeling off the photoresist and the metal layer on the photoresist;

[0119] Step S13: coating photoresist again on the processed substrate, and the photoresist coated again covers the substrate and the metal layer inside;

[0120] Step S14: exposing and developing the photoresist coated again corresponding to the metal layer to obtain a new processed substrate, and entering step S11 until the number of metal layers reaches a preset value. The preset value can be 2, 3, 4, etc.

[0121] On the basis of any of the above-mentioned embodiments, in an embodiment of the present application, when the island cover comprises at least one metal layer, after the single-crystal two-dimensional material layer with a preset number of layers is prepared on the substrate as a substrate by using the mechanical peeling method, it further comprises:

[0122] preparing a conductive connection layer on the substrate;

[0123] Correspondingly, coating photoresist on the substrate, and the photoresist covers the substrate inside comprises:

[0124] coating photoresist on the substrate, and the photoresist covers the substrate and the metal connection layer inside.

[0125] For some special single-crystal two-dimensional materials, such as graphene, the connection stability of the metal layer and the single-crystal two-dimensional material layer is relatively poor, and by setting the conductive connection layer, the connection stability between the island cover and the substrate can be enhanced, thereby enhancing the structural stability of the super-smooth sheet.

[0126] The material of the conductive connection layer can be a material with good connection stability such as chromium or titanium. The conductive connection layer can be processed together with the metal layer of the island cover, that is, a small amount of connection layer is first sputtered or deposited, and then the metal layer of the island cover is sputtered, but the present application does not limit this.

[0127] In any of the above embodiments, in an embodiment of the present application, separating the super slippery sheet from the substrate comprises:

[0128] pressing the super slippery sheet with the transfer head in a vertical direction;

[0129] lifting the super slippery sheet and transferring the super slippery sheet to a new substrate.

[0130] Please refer to Figures 15 to 17 , the transfer head comprises a glass substrate, a polydimethylsiloxane (PDMS) protrusion arranged on the lower surface of the glass substrate, and a layer of high polymer coated on the outer surface of the PDMS protrusion. The transfer head presses the super slippery sheet in a vertical direction, and after transferring the super slippery sheet to a new substrate, the high polymer is heated to complete the transfer.

[0131] The transfer direction of the super slippery sheet in the present application is the vertical direction. The traditional transfer method of the super slippery sheet is to separate the upper and lower super slippery sheets by shear stress using a tungsten needle, and then lift the upper super slippery sheet. In the present application, the first step of shearing is not required, and the super slippery sheet can be directly lifted by the transfer sheet, which is more efficient and faster.

[0132] The following will take an island cover comprising two metal layers as an example to further illustrate the manufacturing method in the present application.

[0133] Step S301: a single-crystal two-dimensional material layer with a preset number of layers is prepared on the substrate as a base by a mechanical peeling method, wherein the preset number of layers is not more than ten.

[0134] This step please refer to Figure 6 .

[0135] Step S302: photoresist is coated on the substrate, and the photoresist covers the inside of the base.

[0136] This step please refer to Figure 10 .

[0137] Step S303: the photoresist corresponding to the base is exposed and developed to obtain a treated substrate.

[0138] This step please refer to Figure 11 .

[0139] Step S304: please refer to Figure 18 , a first metal layer 5 is formed on the treated substrate.

[0140] Step S305: please refer to Figure 19 , the photoresist and the first metal layer on the photoresist are peeled off.

[0141] Step S306: Please refer to Figure 20 After processing, photoresist 4 is coated again on the substrate, and the photoresist 4 is coated again to cover the substrate and the first metal layer 5 inside.

[0142] Step S307: Please refer to Figure 21 The photoresist 4, which is recoated to correspond to the first metal layer 5, is exposed and developed to obtain a new processed substrate.

[0143] Step S308: Please refer to Figure 22 A second metal layer 6 is formed on the newly processed substrate.

[0144] Step S309: Please refer to Figure 23 The recoated photoresist 4 and the second metal layer 6 on the recoated photoresist 4 are peeled off to obtain a superslip sheet including a first metal layer 5 and a second metal layer 6.

[0145] The super-lubricating properties of traditional graphite islands on graphene with 5 layers or less (monolayer) are as follows: Figure 24 As shown, the horizontal axis represents normal force, and the vertical axis represents frictional force. Under loading conditions, the fitting relationship between normal force and frictional force is y = 0.00088186x + 0.42922, and under unloading conditions, the fitting relationship is y = 0.00068654x + 0.37621. Traditional graphite islands can maintain excellent superlubricating properties on a small number of layers (5 layers or less) of two-dimensional materials such as graphene, confirming the feasibility of the bottom superlubricating surface in this application as a new generation of superlubricating sheet.

[0146] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section.

[0147] The super-lubricating sheet and its manufacturing method provided in this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this application. It should be noted that those skilled in the art can make several improvements and modifications to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. An ultra- slip sheet, characterized by, The application relates to a super-slip sheet, comprising: a substrate, wherein the substrate comprises a preset number of monocrystalline two-dimensional material layers, and the preset number of layers is not more than ten; and an island cover fixedly connected to an upper surface of the substrate; wherein the island cover is provided with a transfer part on a surface away from the substrate to facilitate transfer of the super-slip sheet; the transfer part comprises a protrusion; the island cover comprises at least one conductive layer; when the number of layers of the conductive layer is two or more, the size of a next conductive layer is less than or equal to the size of a previous conductive layer in a direction away from the substrate; the island cover is made of a conductive material, and the substrate and the island cover can be electrically connected. When the conductive layer is a metal layer, the application further comprises: a conductive connection layer arranged between the substrate and the island cover. The island cover comprises two metal layers. The thickness of the island cover is greater than 100 nm. The application further relates to a method for preparing a super-slip sheet, comprising: obtaining an island cover, wherein an upper surface or / and a lower surface of the island cover is an atomically flat surface; transferring or growing a preset number of monocrystalline two-dimensional material layers on any atomically flat surface as a substrate to obtain a super-slip sheet, wherein the preset number of layers is not more than ten.

2. The ultra- slide of claim 1, wherein, Alternatively, the application relates to a method for preparing a super-slip sheet, comprising: preparing a preset number of monocrystalline two-dimensional material layers on a substrate by a mechanical exfoliation method, wherein the preset number of layers is not more than ten; forming an island cover on the substrate to obtain a super-slip sheet on the substrate; and separating the super-slip sheet from the substrate.

3. The ultra- slide of claim 1, wherein, The application further relates to a method for preparing an island cover, comprising: coating photoresist on the substrate, wherein the photoresist covers the substrate inside; exposing and developing the photoresist corresponding to the substrate to obtain a processed substrate; depositing an island cover layer on the processed substrate; and stripping the photoresist and the island cover layer on the photoresist to form the island cover on the substrate. When the island cover comprises at least one metal layer, the application further comprises: preparing a conductive connection layer on the substrate after the step of preparing a preset number of monocrystalline two-dimensional material layers on a substrate by a mechanical exfoliation method.

4. The ultra- slide of claim 1, wherein, Correspondingly, the step of coating photoresist on the substrate, wherein the photoresist covers the substrate inside, comprises: coating photoresist on the substrate, wherein the photoresist covers the substrate and the conductive connection layer inside.

5. The ultra- slide of claim 1, wherein, When the island cover comprises at least two metal layers, the step of depositing an island cover layer on the processed substrate and stripping the photoresist and the island cover layer on the photoresist to form the island cover on the substrate comprises: step S11: forming a metal layer on the processed substrate; step S12: stripping the photoresist and the metal layer on the photoresist; step S13: coating photoresist on the processed substrate again, wherein the photoresist again covers the substrate and the metal layer inside; step S14: exposing and developing the photoresist again corresponding to the metal layer to obtain a new processed substrate, and entering step S11 until the number of layers of the metal layer reaches a preset value.

6. A method of making a super-slip sheet based on the super-slip sheet of claim 1, characterized by, The step of separating the super-slip sheet from the substrate comprises: pressing the super-slip sheet in a vertical direction by a transfer head; lifting the super-slip sheet; and transferring the super-slip sheet to a new substrate. ​ ​ ​ ​ 7. The method for manufacturing a superslipper as described in claim 6, characterized in that, ​ ​ ​ ​ 8. The method for manufacturing a superslipper as described in claim 7, characterized in that, ​ ​ ​ ​ 9. The method for manufacturing a superslipper as described in claim 8, characterized in that, ​ ​ ​ ​ ​ 10. The method of claim 6 to 9, wherein ​ ​ ​

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