Elastic seal assembly for material stacking, manufacturing method and material stacking method

Abstract

The invention discloses an elastic seal assembly for material stacking, a manufacturing method and a material stacking method, and belongs to the technical field of material preparation. The invention discloses an elastic seal assembly for material stacking. The elastic seal assembly comprises a base, an elastic inclined plane seal and a plane adhesion film, the elastic inclined plane seal comprises an inclined plane, and the included angle between the inclined plane and the horizontal plane is 3-15 degrees. The plane adhesion film is attached to the inclined plane, and the substrate is arranged on the surface corresponding to the inclined plane. According to the elastic seal assembly for material stacking, the surface for picking up the materials is arranged to be the inclined face, the inclined face enables the picked-up materials to be gradually attached to the materials below from the edge instead of being wholly and directly in contact with the materials below, and therefore automatic discharging of impurity molecules between the two layers of materials can be achieved; and a bubble-free, bubble-free, wrinkle-free and ultra-clean stacking interface is obtained.

Description

Technical Field

[0001] This invention relates to the field of materials preparation technology, and in particular to an elastic stamp assembly for material stacking, a manufacturing method thereon, and a material stacking method. Background Technology

[0002] The transfer and stacking of materials, especially two-dimensional and three-dimensional materials, is key to the development of van der Waals electronics, and these technologies are also considered indispensable processes for the future industrialization of two-dimensional semiconductors. Achieving "cleanliness" and "non-destructiveness" has always been the core objective of these technologies.

[0003] Currently, much research is focused on developing large-scale transfer and stacking technologies to improve yield, enhance device performance, reduce process temperatures, and further support the realization of 2D chip and 3D integration concepts. Among these explorations, "dry" processes are particularly emphasized to overcome the problem of residual organic contamination on the surface after polymer involvement. However, these methods primarily address macroscopic surface contamination. A more challenging issue is interlayer microscopic contamination: before stacking, small molecules (such as H2O and O2) may be physically adsorbed on the material surface, or air molecules may be directly trapped during stacking, leading to severe interlayer problems. Due to the nano-confinement effect of the confined space, these molecules become stable and difficult to expel after stacking. These molecules significantly affect the transport properties and stability of the device, and may even lead to material or device failure. An ideal strategy is to perform stacking directly under high vacuum and high temperature conditions. However, considering process complexity, cost control, and the need for future large-scale mass production, the focus should be on developing simple, scalable, and ultra-clean stacking methods. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a flexible stamp assembly for material stacking and a method for manufacturing it. This flexible stamp assembly enables the direct removal of interlayer impurity molecules during material stacking, and is simple and easy to implement.

[0005] Accordingly, the present invention also provides a material stacking method using the above-described flexible stamp assembly.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A flexible stamp assembly for material stacking includes a substrate, a flexible bevel stamp, and a planar adhesive film; wherein the flexible bevel stamp includes a bevel at an angle of 3-15 degrees to a horizontal plane; the planar adhesive film is attached to the bevel; and the substrate is disposed on a surface corresponding to (opposite to) the bevel.

[0008] The elastic inclined stamp is generally in the shape of a right trapezoid.

[0009] The height h0 of the first side of the elastic beveled stamp and the height h1 of the second side of the elastic beveled stamp conform to the following relationship. ;in .

[0010] The thickness of the planar adhesive film is no greater than 100 μm.

[0011] The flexible beveled stamp is made of polymer, the planar adhesive film is made of polymer, and the substrate is made of hard glass.

[0012] The above-mentioned method for manufacturing a flexible stamp component for material stacking includes the following steps:

[0013] Design a bevel mold according to the pre-designed dimensions, and use the bevel mold to make an elastic bevel stamp;

[0014] A planar mold is designed according to the pre-designed dimensions, and a planar adhesive film is made using the planar mold.

[0015] The planar adhesive film is adhered to the inclined surface of the elastic inclined stamp, and a substrate is attached to the corresponding surface of the elastic inclined stamp to obtain an elastic stamp assembly.

[0016] The elastic stamp assembly for material stacking can be obtained by heating and baking the elastic stamp assembly.

[0017] Wherein, the Rq (root mean square value of surface roughness) of the elastic inclined stamp and the planar adhesive film is not greater than 1 nm. Preferably, the substrate of the inclined mold is mica; and / or, the substrate of the planar mold is mica.

[0018] The substrate and the elastic inclined stamp are bonded together through plasma activation treatment;

[0019] The heating and baking process is carried out at a temperature of 40-60°C for 10-30 minutes.

[0020] A material stacking method employing the aforementioned flexible stamp assembly for material stacking; the material stacking method specifically includes the following steps:

[0021] S1: Pick up a material using the elastic stamp assembly for material stacking;

[0022] S2: Align the flexible stamp assembly for material stacking with another material on the substrate in a preset orientation, with the flexible stamp assembly for material stacking positioned above the other material;

[0023] S3: The substrate is heated to allow the flexible stamp assembly for material stacking to fall until the planar adhesive film makes full contact with the other material to complete the material stacking; the falling speed of the flexible stamp assembly for material stacking is 5-10 μm / s;

[0024] S4: After stacking, a baking process is performed; the baking temperature is 40-60℃ and the baking time is 15-30 minutes.

[0025] S5: After baking, the elastic bevel stamp and the flat adhesive film are separated to complete the material stacking.

[0026] If air bubbles or bulges appear during the stacking process, the elastic stamp assembly used for material stacking is lifted and then pressed down again.

[0027] Specifically, in step S3, the falling speed of the elastic stamp assembly used for stacking two-dimensional materials is slower as the angle between the inclined plane and the horizontal plane is smaller.

[0028] In step S3, the substrate is heated to a temperature of 120-180°C.

[0029] The beneficial effects of this invention are as follows:

[0030] (1) The elastic stamp assembly for material stacking of the present invention sets the surface for picking up the material as a slope, which makes the picked-up material not directly contact the material below, but gradually adhere to the material below from the edge. This enables the automatic discharge of impurity molecules between the two layers of materials, resulting in a bubble-free, water bubble-free, wrinkle-free and ultra-clean stacking interface.

[0031] (2) The material stacking method of the present invention uses an elastic inclined stamp and a flat adhesive film to operate the material to be stacked, thereby realizing the direct discharge of interlayer impurity molecules during the material stacking process and obtaining an ultra-clean stacking structure.

[0032] (3) The material stacking method of the present invention can be applied to the clean stacking of different kinds of two-dimensional materials and some three-dimensional components (such as Au thin film and Al2O3 thin film), and is also applicable to large-area materials, complex corner structures and superlattice structures. The performance of the devices prepared by this method has been significantly improved. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the overall structure of the flexible stamp assembly for material stacking according to the present invention.

[0034] Figure 2 This is a schematic diagram of the structure of the elastic inclined surface stamp of the present invention.

[0035] Figure 3 This is a physical image of the flexible beveled stamp of the present invention.

[0036] Figure 4 This is a schematic diagram of the manufacturing method of the elastic stamp assembly for material stacking according to the present invention.

[0037] Figure 5 The images show a comparison of the surface roughness of the planar adhesive films obtained in Examples 1 to 5.

[0038] Figure 6 This is a surface morphology diagram of the planar adhesive film obtained in Example 3.

[0039] Figure 7 This is a surface morphology diagram of the planar adhesive film obtained in Example 4.

[0040] Figure 8 This is an overall schematic diagram of the layered material stacking method of the present invention.

[0041] Figure 9 The images show a comparison of the surface morphology of the MoS2 layered materials obtained in Example 6 and Comparative Example 1.

[0042] Figure 10 The graphs show the performance test results of the hBN / MoS2 top-gate transistor devices obtained in Example 7 and Comparative Example 2.

[0043] Figure 11 This is an optical image of the layered material obtained in Example 8.

[0044] Figure 12 This is an optical image of the layered material obtained in Example 9.

[0045] Figure 13 This is an optical image of the layered material obtained in Example 10.

[0046] Figure 14 This is an optical image of the layered material obtained in Example 11.

[0047] Figure 15 This is an optical image of the layered material obtained in Example 7.

[0048] Figure 16 This is an optical image of the layered material obtained in Example 12.

[0049] Figure 17 Optical and cross-sectional electron microscope images of the torsion bilayer MoS2 structure obtained in Example 13.

[0050] Figure 18 Optical image of the MoS2 / WSe2 multilayer stacked superlattice structure prepared in Example 14.

[0051] Reference numerals: 100-substrate, 200-flexible bevel stamp, 210-bevel, 220-surface, 300-flat adhesive film. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0053] See Figure 1 and Figure 2 The present invention provides a flexible stamp assembly for material stacking, comprising a substrate 100, a flexible inclined stamp 200, and a planar adhesive film 300; wherein the flexible inclined stamp 200 includes an inclined surface 210, the inclined surface 210 being at an angle θ of 3 to 15 degrees with the horizontal plane; the planar adhesive film 300 is attached to the inclined surface 210, and the substrate 100 is disposed on a surface 220 corresponding to the inclined surface.

[0054] In this embodiment, the materials to be stacked (e.g., two-dimensional materials) are adsorbed onto the planar adhesive film 300, and the moving mechanism (e.g., a robotic arm) that controls the movement of the entire elastic stamp assembly for material stacking is mounted on the substrate 100.

[0055] For a better option, see [link to previous section]. Figure 2 The elastic inclined stamp 200 is generally in the shape of a right trapezoid. That is, the surface 220 of the elastic inclined stamp 200 that contacts the base 100 is parallel to the horizontal plane. In this embodiment, the height h0 of the first side of the elastic inclined stamp 200 and the height h1 of the second side of the elastic inclined stamp 200 conform to the following relationship, namely... ;in .

[0056] Furthermore, the area of ​​the inclined surface of the flexible inclined stamp 200 shall not be less than the surface area of ​​the material to be picked up. l is the length of the surface of the flexible inclined stamp in contact with the substrate, and its length can be designed according to actual needs.

[0057] Preferably, the thickness of the planar adhesive film 300 is no more than 100 μm, in order to facilitate the formation of conformal contact and shorten the subsequent dissolution time.

[0058] The flexible beveled stamp 200 is made of a polymer, and the material is sufficient to ensure that the flexible beveled stamp has high elasticity and high toughness; polydimethylsiloxane (PDMS) is preferred. The dimensions of the flexible beveled stamp 200 (e.g., Figure 2The h0, h1, h2, l, etc. in the model can be freely customized according to the size of the materials to be stacked.

[0059] The planar adhesive film 300 is made of polymers, including but not limited to PDMS, PMMA, PVA, PPC, and PS. The raw materials for the planar adhesive film 300 can be PDMS (A:B=8:1), PMMA (495 A4 prepolymer), PVA (10wt%, molecular weight approximately 45,000), PS (10wt%, molecular weight approximately 35,000, solvent is toluene), or PPC (10wt%, molecular weight approximately 50,000). The polymer concentration determines the VAL thickness, and the curing conditions (temperature, time) can be optimized according to the material characteristics to reduce organic residues and improve surface quality.

[0060] The substrate 100 is made of hard glass, which can be ordinary quartz glass.

[0061] See Figure 4 The above-mentioned method for manufacturing a flexible stamp component for material stacking includes the following steps:

[0062] A sloped mold is designed according to pre-designed dimensions. Using this mold, an elastic sloped stamp 200 is fabricated through polymer casting, curing, and demolding steps. Specifically, the elastic sloped stamp 200 is prepared by pouring polymer into a pre-designed sloped mold, followed by casting and demolding to form the sloped stamp. The stamp's size, slope angle, and other parameters can be freely customized using the mold. The resulting elastic sloped stamp 200 is shown in the image. Figure 3 As shown, Figure 3 The image shows two flexible inclined plane stamps with different angles θ.

[0063] A planar mold is designed according to the pre-designed dimensions. The planar adhesive film 300 is produced by polymer casting, curing and demolding steps using the planar mold. The flat planar adhesive film 300 is also formed by casting and demolding, and the thickness is as thin as possible.

[0064] The planar adhesive film 300 is adhered to the inclined surface 210 of the elastic inclined stamp 200, and the substrate 100 is attached to the corresponding surface 220 of the elastic inclined stamp 200 to obtain an elastic stamp assembly.

[0065] The elastic stamp assembly for material stacking can be obtained by heating and baking the elastic stamp assembly.

[0066] It should be noted that the area of ​​the base 100 can be larger than the area of ​​the surface 220 of the flexible inclined stamp 200.

[0067] Among them, see Figure 4 The planar adhesive film 300 is obtained by forming and removing the film on a flat substrate of a planar mold. In order to make the planar adhesive film have a high degree of flatness, a flatter material, such as SiO2, mica or glass, can be introduced on the surface of the planar mold as a liner. The preferred material of the substrate is mica.

[0068] The lining of the inclined mold contains mica.

[0069] The substrate 100 and the elastic inclined stamp 200 are bonded together through plasma activation treatment;

[0070] And / or, the temperature of the heating and baking treatment is 40–60°C, and the heating and baking time is 10–30 minutes.

[0071] See Figure 8 A material stacking method employing the aforementioned flexible stamp assembly for material stacking; the material stacking method specifically includes the following steps:

[0072] S1: Pick up a material using the elastic stamp assembly for material stacking.

[0073] S2: Align the elastic stamp assembly for material stacking with another material on the substrate in a preset orientation, with the elastic stamp assembly for two-dimensional material stacking located above the other material; in this embodiment, the material picked up and the material on the substrate may be the same or different.

[0074] S3: The substrate is heated, and the flexible stamp assembly for material stacking is slowly and horizontally lowered until the planar adhesive film comes into complete contact with the other material to complete the material stacking; the falling speed of the flexible stamp assembly for material stacking is 5–10 μm / s; preferably, the substrate of the flexible stamp assembly remains horizontal during the falling process.

[0075] S4: After stacking, a baking process is performed; the baking temperature is 40–60℃ and the baking time is 15–30 minutes.

[0076] S5: After baking, the flexible beveled stamp and the planar adhesive film are separated to complete the material stacking. This separation can be performed mechanically using glass or with a suitable solvent. For PDMS-VAL-based samples, separation can be achieved through mechanical peeling, without the need for additional solvent treatment.

[0077] The material stacking method of the present invention uses an inclined elastic stamp component to achieve clean stacking between materials through gradual contact, and effectively removes interlayer molecular impurities during the stacking process.

[0078] Preferably, the alignment in step S2 is performed with the aid of a microscope.

[0079] If air bubbles or bulges appear during the stacking process, the elastic stamp assembly used for material stacking is lifted and then pressed down again.

[0080] Specifically, in step S3, the falling speed of the elastic stamp assembly used for material stacking is such that the smaller the angle θ between the inclined plane and the horizontal plane, the slower the falling speed.

[0081] In step S3, the substrate is heated to 120-180℃. The purpose of heating the substrate is to promote the desorption of impurity molecules, ensuring that the impurity molecules are desorbed from the material surface and removed under the action of the stamp. More preferably, the substrate heating is in-situ heating. Here, heating refers to bottom heating during the material stacking process to promote the removal of bubbles, water bubbles, etc. between the stacked layers, achieving a cleaner interface.

[0082] The interlayer material stacking method of this invention is applicable to the clean stacking of various two-dimensional materials (such as MoS2 and WSe2) and some three-dimensional components (such as Au thin films and Al2O3 thin films). This method can achieve clean stacking of complex multilayer two-dimensional materials, including corner heterostructures, two-dimensional superlattice structures, and wafer-level ultra-large area two-dimensional materials. Two-dimensional transistor devices fabricated using this method can achieve higher performance.

[0083] Example 1:

[0084] This embodiment fabricates a flexible stamp assembly for stacking two-dimensional materials.

[0085] Part 1: Making the Flexible Bevel Stamp 200 (EBS) and the Flat Adhesive Film 300 (VAL).

[0086] The preparation process of EBS is as follows: See Figure 4 The PDMS prepolymer (A:B=8:1) was poured into a 3D printing mold and cured in a vacuum oven at 90–120℃ for about 4 hours before demolding to obtain EBS with the desired geometric features.

[0087] VAL was prepared using the same process, with PDMS (A:B=8:1) selected as the material.

[0088] The 3D printed mold (including flat mold and inclined mold) in this embodiment is made of thermoplastic plastic and its inner lining is MoS2.

[0089] Part Two: Assembly.

[0090] The VAL obtained in the first part is naturally adhered to the inclined surface of EBS to form an EBS@VAL assembly. Subsequently, the EBS@VAL is mechanically bonded to a quartz glass substrate 100 through plasma activation treatment to obtain a complete glass@EBS@VAL tool. After assembly, it is baked on a hot plate at 40–60°C for 10 minutes to ensure full interface adhesion.

[0091] Example 2:

[0092] The steps in this embodiment are the same as in Embodiment 1, except that the inner lining of the flat mold and the inclined mold is SiO2.

[0093] Example 3:

[0094] The steps in this embodiment are the same as in embodiment 1, except that the inner lining of the flat mold and the inclined mold is mica.

[0095] Example 4:

[0096] The steps in this embodiment are the same as in embodiment 1, except that the inner lining of the flat mold and the inclined mold is glass.

[0097] Example 5:

[0098] The steps in this embodiment are the same as in embodiment 1, except that the inner lining of the flat mold and the inclined mold is made of plastic.

[0099] Figure 5 This is a schematic diagram showing the surface roughness test results of the planar adhesive films 300 prepared in Examples 1 to 5. Figure 5 As can be seen, the surface roughness of planar adhesive films obtained using different substrate materials varies. In this invention, it is considered that the surface roughness Rq of the planar adhesive film 300 should be no greater than 1 nm to ensure that the adhered two-dimensional material does not undergo deformation or damage. Figure 5 As shown, Figure 5 Contains " The planar adhesive film 300 obtained by the embodiment with mica and SiO2 as the inner lining of the “” symbol has a small surface roughness, which meets the requirements of the present invention.

[0100] Figure 6 This is a surface microstructure diagram of the planar adhesive film obtained in Example 3. Figure 7 This is a microstructure diagram of the planar adhesive film obtained in Example 4. From... Figure 7 As can be seen, the surface of the planar adhesive film in Example 4 is uneven. Figure 6 As can be seen from the example, the planar adhesive film obtained in Example 3 is relatively smooth, which is beneficial to the flatness of the two-dimensional material it adheres to, thereby improving the quality of the final stacked material.

[0101] Example 6:

[0102] See Figure 8 This embodiment provides a material stacking method, using MoS2 sheets and employing an elastic stamp assembly (θ = 3 degrees) for material stacking fabricated in Example 3. The stacking method includes the following steps:

[0103] S1: MoS2 flake acquisition: Transferring two-dimensional MoS2 flakes onto the VAL surface to form a "glass@EBS@VAL@material" assembly. The two-dimensional MoS2 flakes can be obtained by mechanically peeling them off from bulk MoS2 crystals with adhesive tape, or by other methods.

[0104] S2: Stacking Step: Using another MoS2 sheet on the substrate as the bottom material, the above assembly is mounted onto the microscope robotic arm, aligned, and slowly lowered. Simultaneously, the target substrate is preheated to approximately 150°C. As the edge of the EBS bevel first contacts the substrate, the assembly continues to slowly descend, gradually achieving complete material contact. In this embodiment, the falling speed of the "glass@EBS@VAL@material" assembly is 5 μm / s.

[0105] S3: After stacking, bake at 60℃ for 30 minutes, then separate EBS and VAL to complete the stacking of MoS2 sheets.

[0106] Comparative Example 1:

[0107] In this embodiment, flexible flat stamps are stacked, and the stacking method is the same as in embodiment 6.

[0108] The microstructure images of the layered materials, i.e., the MoS2 / MoS2 structures, obtained in Example 6 and Comparative Example 1 are shown below. Figure 9 .from Figure 9 As can be seen, the MoS2 / MoS2 structure using planar stamp stacking in Comparative Example 1 contains a large number of air bubbles and water bubbles; while the MoS2 / MoS2 structure using elastic inclined stamp stacking in Example 6 has a smooth surface and interface without impurities, exhibiting ultra-clean characteristics.

[0109] Example 7:

[0110] The hBN / MoS2 top-gate transistor device prepared in this embodiment.

[0111] The flexible stamp assembly (θ is 15 degrees) for material stacking, fabricated using Example 3, includes the following steps in the stacking method:

[0112] S1: Pick up hBN sheet: Transfer two-dimensional hBN (hexagonal boron nitride) sheet to the VAL surface to form a "glass@EBS@VAL@material" assembly.

[0113] S2: Stacking Step: Using MoS2 on the substrate as the bottom material, the above assembly is mounted onto the microscope robotic arm, aligned, and slowly lowered. Simultaneously, the target substrate is preheated to approximately 150°C. As the edge of the EBS bevel first contacts the substrate, the assembly continues to slowly descend, gradually achieving complete material contact. In this embodiment, the falling speed of the "glass@EBS@VAL@material" assembly is 10 μm / s.

[0114] S3: After stacking, bake at 40–60℃ for 15–30 minutes, then separate EBS and VAL to complete the stacking of hBN / MoS2.

[0115] Comparative Example 2:

[0116] In this embodiment, flexible flat stamps are stacked, and the stacking method is the same as in embodiment 7.

[0117] The performance test results of the hBN / MoS2 top-gate transistor devices obtained in Example 7 and Comparative Example 2 are shown in the figure. Figure 10 .from Figure 10 As can be seen from the data, the device prepared in Example 7 has significantly better performance than the control group, with less hysteresis, higher mobility, lower subthreshold swing, and larger on / off ratio. This fully demonstrates that the method can effectively improve the cleanliness of materials, thereby improving device performance.

[0118] Example 8:

[0119] This embodiment provides a material stacking method. The material is hBN sheet, and an elastic stamp assembly (θ is 5 degrees) for material stacking is used, which was prepared in Embodiment 3. The stacking method includes the following steps:

[0120] S1: Pick up hBN sheet: Transfer the two-dimensional hBN sheet to the VAL surface to form a "glass@EBS@VAL@material" assembly.

[0121] S2: Stacking Step: Using another piece of hBN on the substrate as the bottom material, the above assembly is mounted onto the microscope robotic arm, aligned, and slowly lowered. Simultaneously, the target substrate is preheated to approximately 120°C. When the edge of the EBS bevel first contacts the substrate, the assembly continues to slowly descend, gradually ensuring complete material contact. In this embodiment, the falling speed of the "glass@EBS@VAL@material" assembly is 5 μm / s.

[0122] S3: After stacking, bake at 40–60℃ for 15–30 minutes, then separate EBS and VAL to complete the stacking of hBN sheets.

[0123] Example 9:

[0124] The steps in this embodiment are the same as in embodiment 8, except that the stacking material is graphene Gr.

[0125] Example 10:

[0126] The steps in this embodiment are the same as in embodiment 8, except that the stacking material is WSe2.

[0127] Example 11:

[0128] The steps in this embodiment are the same as in embodiment 8, except that the material picked up is hBN and the material on the substrate is Gr.

[0129] Example 12:

[0130] The steps in this embodiment are the same as in embodiment 8, except that the material picked up is hBN and the material on the substrate is WSe2.

[0131] Optical microscope images of the layered materials obtained in Examples 7 to 12 are shown below. Figures 11 to 16 . Figure 11 An optical microscope image of the hBN / hBN layered material prepared in Example 8; Figure 12 Optical microscope image of the Gr / Gr layered material prepared in Example 9; Figure 13 An optical microscope image of the WSe2 / WSe2 layered material prepared in Example 10; Figure 14 This is an optical microscope image of the hBN / Gr layered material prepared in Example 11. Figure 15 Optical microscope image of the hBN / MoS2 layered material prepared in Example 7. Figure 16 Optical microscope image of the hBN / WSe2 layered material prepared for Example 12. From... Figures 11 to 16 As can be seen, this method can achieve clean stacking of various two-dimensional materials.

[0132] Example 13:

[0133] This embodiment demonstrates the stacking of two-layer MoS2 at a corner.

[0134] This embodiment provides a material stacking method. The material is a MoS2 sheet, and the method uses an elastic stamp assembly (θ = 5 degrees) for material stacking fabricated in Example 3. The stacking method includes the following steps:

[0135] S1: MoS2 Flake Pickup: A two-dimensional MoS2 flake is transferred onto the VAL surface to form a "glass@EBS@VAL@material" assembly. The two-dimensional MoS2 flake is prepared by chemical vapor deposition (CVD). Note that a flexible stamp assembly of similar size to the two-dimensional material being processed must be used to ensure complete coverage of the two-dimensional material.

[0136] S2: Stacking Step: Using another MoS2 sheet on the substrate as the bottom material, mount the above assembly onto the microscope robotic arm, align it, and slowly lower it. Simultaneously, preheat the target substrate to approximately 180°C. Ensure a slight angle exists between the upper and lower materials. When the edge of the EBS bevel first contacts the substrate, continue the slow descent to gradually achieve complete material contact. In this embodiment, the falling speed of the "glass@EBS@VAL@material" assembly is 6 μm / s.

[0137] S3: After stacking, bake at 40–60℃ for 15–30 minutes, then separate EBS and VAL to complete the stacking of MoS2 sheets.

[0138] from Figure 17 The optical images show that the stacked interface of the corner bilayer MoS2 has no obvious defects.

[0139] Example 14:

[0140] This embodiment involves stacking a large-area MoS2 / WSe2 / MoS2 / WSe2 superlattice.

[0141] This embodiment uses the flexible stamp assembly (θ is 5 degrees) for material stacking manufactured in Embodiment 3. The stacking method includes the following steps:

[0142] S1: Pick up WSe2 sheet: Transfer the two-dimensional WSe2 sheet to the VAL surface to form a "glass@EBS@VAL@material" assembly.

[0143] S2: Stacking Step: Using another MoS2 sheet on the substrate as the bottom material, mount the above assembly onto the microscope robotic arm, align it, and slowly lower it. Simultaneously, preheat the target substrate to approximately 150°C. Ensure there is a corner between the upper and lower materials. When the edge of the EBS bevel first contacts the substrate, continue the slow descent to gradually achieve complete material contact. In this embodiment, the falling speed of the "glass@EBS@VAL@material" assembly is 6 μm / s.

[0144] S3: After stacking, bake at 40°C for 15 minutes, then separate EBS and VAL to complete the stacking of MoS2 / WSe2 sheets.

[0145] S4: Lift the flexible stamp assembly used for material stacking and return it to its original position.

[0146] S5: Pick up the MoS2 sheet again: Transfer the two-dimensional MoS2 sheet to the VAL surface to form a "glass@EBS@VAL@material" assembly.

[0147] S6: Using the already stacked MoS2 / WSe2 sheets as the base material, mount the above assembly onto the microscope robotic arm, align it, and slowly lower it. Simultaneously, preheat the target substrate to approximately 150°C. Ensure there is a corner between the upper and lower materials. When the edge of the EBS bevel first contacts the substrate, continue the slow descent to gradually achieve complete material contact.

[0148] S7: After the second stacking is completed, bake at 40℃ for 15 minutes, then separate EBS and VAL to complete the stacking of MoS2 / WSe2 / MoS2 sheets.

[0149] S8: Repeat steps S4 to S7, this time picking up the WSe2 thin film to obtain the MoS2 / WSe2 / MoS2 / WSe2 superlattice.

[0150] from Figure 18 It can be seen that this embodiment achieves large-area MoS2 / WSe2 / MoS2 / WSe2 superlattice stacking.

[0151] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0152] The parts of this invention not described in detail are well-known in the art. The above embodiments are provided merely for the purpose of describing the invention and are not intended to limit the scope of the invention. The scope of the invention is defined by the appended claims. All equivalent substitutions and modifications made without departing from the spirit and principles of the invention should be covered within the scope of the invention.

Claims

1. A flexible stamp assembly for material stacking, characterized in that, The resilient stamp assembly for material stacking includes a substrate, a resilient beveled stamp, and a planar adhesive film; wherein the resilient beveled stamp includes a bevel at an angle of 3-15 degrees to the horizontal plane; the planar adhesive film is attached to the beveled surface, and the substrate is disposed on a surface corresponding to the beveled surface.

2. The flexible stamp assembly for material stacking according to claim 1, characterized in that, The elastic inclined stamp is generally in the shape of a right-angled trapezoid. And / or, the flexible beveled stamp is made of a polymer, the planar adhesive film is made of a polymer, and the substrate is made of hard glass.

3. The flexible stamp assembly for material stacking according to claim 1, characterized in that, The height h0 of the first side of the elastic beveled stamp and the height h1 of the second side of the elastic beveled stamp conform to the following relationship. ;in .

4. The flexible stamp assembly for material stacking according to claim 1, characterized in that, The thickness of the planar adhesive film is no greater than 100 μm.

5. The method for manufacturing the flexible stamp assembly for material stacking according to any one of claims 1 to 4, characterized in that, Includes the following steps: Design a bevel mold according to the pre-designed dimensions, and use the bevel mold to make an elastic bevel stamp; A planar mold is designed according to the pre-designed dimensions, and a planar adhesive film is made using the planar mold. The planar adhesive film is adhered to the inclined surface of the elastic inclined stamp, and a substrate is attached to the corresponding surface of the elastic inclined stamp to obtain an elastic stamp assembly. The elastic stamp assembly for material stacking can be obtained by heating and baking the elastic stamp assembly.

6. The method for manufacturing the flexible stamp assembly for material stacking according to claim 5, characterized in that, The Rq of the elastic inclined stamp and the planar adhesive film is no greater than 1 nm.

7. The method for manufacturing the flexible stamp assembly for material stacking according to claim 5, characterized in that, The substrate and the elastic inclined stamp are bonded together through plasma activation treatment; And / or, the heating and baking treatment is performed at a temperature of 40-60°C for 10-30 minutes.

8. A method for stacking materials, characterized in that, The flexible stamp assembly for material stacking as described in any one of claims 1 to 4 is used; the material stacking method specifically includes the following steps: S1: Pick up a material using the elastic stamp assembly for material stacking; S2: Align the flexible stamp assembly for material stacking with another material on the substrate in a preset orientation, with the flexible stamp assembly for material stacking positioned above the other material; S3: The substrate is heated, and the flexible stamp assembly for material stacking is dropped until the planar adhesive film makes full contact with the other material to complete the material stacking; the dropping speed of the flexible stamp assembly for material stacking is 5-10 μm / s; S4: After stacking, a baking process is performed; the baking temperature is 40-60℃ and the baking time is 15-30 minutes. S5: After baking, the elastic inclined stamp and the flat adhesive film are separated to complete the stacking of two-dimensional materials.

9. The material stacking method according to claim 8, characterized in that, If air bubbles or bulges appear during the stacking process, lift the elastic stamp assembly used for material stacking and press it down again.

10. The material stacking method according to claim 8, characterized in that, The falling speed of the elastic stamp assembly used for material stacking in step S3 is specifically that the smaller the angle between the inclined plane and the horizontal plane, the slower the falling speed. And / or, the heating temperature of the substrate in step S3 is 120-180℃.

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