Method for patterning two-dimensional materials based on mask-assisted filtration and displacement overlay transfer

Abstract

This invention discloses a method for patterning two-dimensional materials based on mask-assisted filtration and displacement overprinting. The method includes: constructing a patterned barrier layer on a porous filter membrane substrate using a first mask; depositing two-dimensional material in a defined area using vacuum-assisted filtration to form a two-dimensional material pre-pattern; forming a local protective layer on a target substrate using a second mask and performing surface treatment to create a surface energy difference region on the substrate surface, obtaining a surface-treated pattern, which includes a hydrophilic high surface energy target region and a hydrophobic low surface energy background region; flipping the porous filter membrane substrate and misaligning it with the target substrate, so that the two-dimensional material pre-pattern and the high surface energy target region form a locally overlapping window; and performing overprinting transfer on the target substrate to obtain a high-resolution two-dimensional material micro-pattern defined by the locally overlapping window. This method can obtain high-resolution or specially shaped micro-patterns.

Description

Technical Field

[0001] This invention belongs to the field of micro-nano manufacturing and two-dimensional material device fabrication technology, specifically involving a two-dimensional material patterning method based on mask-assisted filtration and displacement overlay transfer. Background Technology

[0002] Two-dimensional materials (including graphene, MXene, transition metal chalcogenides (TMDs), black phosphorus, and hexagonal boron nitride (h-BN)) have become core materials for constructing next-generation high-performance transistors, highly sensitive sensors, flexible optoelectronic devices, and energy storage devices due to their atomic-level thickness and excellent intrinsic electrical, optical, mechanical, and thermal properties. To meet the urgent needs of microelectronic and optoelectronic devices for high-density integration and miniaturization, it is imperative to achieve high-resolution fabrication of two-dimensional material micro-nano patterns with narrower linewidths and smaller spacing (breaking through from the micrometer to the sub-micrometer level) on target substrates. This is a key foundational process supporting leaps in device performance and large-scale integration.

[0003] In existing two-dimensional material micro / nano fabrication technologies, there has long been an irreconcilable engineering contradiction between "high-resolution patterning" and "low interface contamination / high-fidelity integration." Traditional micro / nano fabrication methods (such as photolithography and electron beam lithography) offer high resolution, but they heavily rely on the coating, development, and stripping processes of photoresist, inevitably introducing organic residues or causing lattice damage on the atomically thin surface of two-dimensional materials. Furthermore, these methods are expensive and have low yields. While solution-based printing or direct writing technologies simplify processes and offer strong substrate adaptability, they are limited by the rheological properties of inks, contact angle hysteresis, and the coffee ring effect, making it difficult to stably achieve submicron-level fine features over large areas.

[0004] Patent application CN111863624A discloses a method for large-scale preparation and patterning of two-dimensional semiconductor thin films, comprising the following steps: substrate pretreatment; photolithography of a target pattern on the pretreated substrate using negative photoresist; preparation of a two-dimensional semiconductor thin film on the substrate with the photoresist pattern using solution self-assembly technology: the substrate is first immersed in an aqueous solution of polydiallyldimethylammonium chloride, and then immersed in an aqueous solution of MoS2, a process that can be repeated multiple times; the thin film obtained on the substrate is immersed in acetone to remove the photoresist, finally obtaining the target MoS2 pattern. The advantages of the method disclosed in the above patent application are that the preparation method is simple and can be operated on any substrate; the film thickness is controllable and patterning can be achieved; the reaction conditions are mild, and it has broad application prospects in the field of high-performance two-dimensional semiconductor thin film electronic devices. However, this method is limited by the mask size, and the resolution of the two-dimensional pattern cannot be further improved.

[0005] Vacuum-assisted filtration (VAF) is a typical liquid-phase self-assembly and patterning method that has attracted much attention due to its unique advantages. This process utilizes negative pressure to drive the directional deposition and densification of two-dimensional nanosheets dispersed in a polar solvent on the surface of a porous filter membrane, forming continuous, uniform, and high-quality films with controllable thickness. Compared to photolithography, the VAF route eliminates the need for photoresist, significantly reducing the risk of interface contamination. Furthermore, by combining mask confinement technology, two-dimensional material pre-patterns corresponding to mask openings can be directly obtained on the filter membrane. In addition, by leveraging the surface energy difference and interfacial capillary forces between the porous filter membrane and the target substrate, this process can selectively transfer pre-patterns from the filter membrane to various target substrates such as silicon wafers and flexible polymers, greatly facilitating the fabrication of heterogeneous devices.

[0006] However, despite the significant advantages of vacuum-assisted filtration in film quality and cleanliness, its pattern resolution faces a severe physical bottleneck. The feature size of this process is limited not only by the machining precision of the physical mask but also by the combined constraints of fluid percolation dynamics and nanosheet stacking behavior during filtration. When the mask opening size is reduced to the micrometer scale (e.g., < 10 μm), micropore blockage, lateral solvent wetting at the edges, and nanosheet diffusion and stacking easily occur, leading to film discontinuities, increased edge burrs, and a significant decrease in pattern fidelity. This limits the resolution of existing "mask-filtration-transfer" routes to the 5 μm range, making it difficult to break through to the submicrometer scale. Clearly, simply relying on improving mask machining precision or reducing the physical opening size is insufficient to effectively address the process limitations imposed by the aforementioned fluid and particle behaviors. Summary of the Invention

[0007] This invention provides a two-dimensional material patterning method based on mask-assisted filtration and displacement overprinting. This method can overcome the limitations of mask size and shape, achieve secondary scaling of resolution relative to the smallest opening of the mask, and obtain high-resolution or special-shaped micro-patterns.

[0008] This invention provides a two-dimensional material patterning method based on mask-assisted filtration and displacement overlay transfer, comprising: (1) A patterned barrier layer is constructed on a porous filter membrane substrate using a first mask, and two-dimensional material is deposited in a defined area by vacuum-assisted filtration. After removing the first mask, a two-dimensional material pre-pattern is formed. (2) A local protective layer is formed on the target substrate using a second mask and surface treatment is performed. A surface energy difference region is constructed on the substrate surface. After removing the second mask, a surface treatment pattern is obtained. The surface treatment pattern includes a hydrophilic high surface energy target region and a hydrophobic low surface energy background region. (3) The porous filter membrane substrate obtained in step (1) is flipped and misaligned with the target substrate after step (2) to form a local overlap window between the two-dimensional material pre-pattern and the high surface energy target area; the capillary force induced by the surface energy difference is used to selectively transfer the two-dimensional material in the overlap window to the target substrate, while the non-overlapping part remains on the porous filter membrane substrate; then the porous filter membrane substrate is separated, and the two-dimensional material is broken at the boundary of the local overlap window, thereby realizing overlay transfer on the target substrate and obtaining a high-resolution two-dimensional material micro-pattern defined by the local overlap window.

[0009] Preferably, the linewidth or feature size of the two-dimensional material micropatterning is determined by the geometric size of the locally overlapping window, and the geometric size is smaller than the minimum feature size of the first mask or the second mask; The geometric dimensions of the locally overlapping window are determined by the relative pose parameters of the two-dimensional material pre-pattern and the surface-treated pattern in the plane; The relative pose parameters include translational displacement, rotation angle, and / or scale difference.

[0010] Preferably, the geometry of the partially overlapping window is defined by the overlapping area in the plane of the two-dimensional material pre-pattern and the surface-treated pattern; The geometric shapes include linear, strip-shaped, ring-shaped, island-shaped, or combinations thereof; Wherein, when the geometric shape is ring-shaped, the geometric shape is formed by the staggered overlap of a first circular pattern and a second circular pattern.

[0011] Preferably, the method for constructing the surface energy difference region in step (2) is a positive pattern pattern, specifically including: First, a hydrophobic layer is formed on the surface of the target substrate, wherein the hydrophobic layer is a hydrophobic monolayer and / or a hydrophobic polymer layer. After covering the second mask, the exposed area of ​​the second mask is subjected to surface activation treatment to remove the hydrophobic material in the exposed area and / or to oxidize and modify it to introduce hydrophilic groups, thereby transforming the exposed area into a hydrophilic high surface energy target area, while the area covered by the second mask remains a hydrophobic low surface energy background area.

[0012] Preferably, the method for constructing the surface energy difference region in step (2) is an inverse patterning pattern, specifically including: First, a hydrophilic layer or an activatable layer is formed on the surface of the target substrate; After covering the second mask, the exposed area of ​​the second mask is hydrophobically treated to form a hydrophobic low surface energy background area. The low surface energy background area is the pattern after surface treatment, while the area covered by the second mask remains a hydrophilic high surface energy target area.

[0013] Preferably, before or during the bonding process of misaligning and aligning the two-dimensional material pre-pattern on the porous filter membrane substrate obtained in step (1) with the surface energy differential pattern on the target substrate obtained in step (2), polar solvent mist or vapor is introduced at the bonding position so that the polar solvent preferentially wets the pattern area after surface treatment and forms a capillary liquid bridge, thereby enhancing the capillary driving force and interface fixation strength in the local overlapping window and inhibiting the wetting and adhesion of the hydrophobic low surface energy background area, thereby improving the transfer selectivity and pattern edge quality.

[0014] Preferably, the solvent of the two-dimensional material dispersion is a polar solvent or a mixed solvent containing polar components, and the static contact angle of the solvent in the high surface energy target region is not greater than 30°, and the static contact angle in the hydrophobic low surface energy background region is not less than 70°.

[0015] Preferably, both the first and second masks are designed with auxiliary positioning marks, thereby forming the first positioning mark and the second positioning mark on the porous filter membrane substrate and the target substrate, respectively. In the misalignment and bonding process of step (3), under the observation of the micro-optical system, the relative position of the plane between the porous filter membrane substrate and the target substrate is first adjusted so that the two-dimensional material pre-pattern layer and the target substrate pattern can be initially aligned over a large range. Based on the initial alignment, the relative displacement is further quantitatively controlled by observation and in conjunction with a high-precision displacement stage. The relative positions of the first positioning mark and the second positioning mark are adjusted for fine alignment, thereby achieving controllable adjustment of the geometric width of the locally overlapping window and continuous adjustable control of the micro-pattern resolution.

[0016] Preferably, the separation method in step (3) includes tangential shear peeling, rolling peeling, or peeling with a set peeling angle to introduce shear force components, causing the two-dimensional material to break at the boundary of the locally overlapping window and reducing edge burrs.

[0017] Preferably, the target substrate after obtaining the two-dimensional material micropattern is subjected to at least one of the following: thermal annealing, solvent cleaning, vacuum drying, or mild plasma treatment, in order to remove interface residues and enhance the bonding between the two-dimensional material and the target substrate.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Breaking the Limits of Mask Precision and Achieving Continuously Adjustable Feature Sizes: This invention utilizes the principle of "misaligned overlay" to successfully overcome the minimum feature size limitation of physical masks by controlling the local overlap between the pre-pattern and the high surface energy region, achieving sub-micron-level high-resolution patterning. Furthermore, by simply adjusting the relative translational displacement between the two, continuous and precise in-situ control of the micropattern linewidth and geometric dimensions can be achieved without replacing the mask.

[0019] 2. Excellent pattern edge quality and highly selective transfer: Based on the capillary force driven mechanism induced by surface energy difference, combined with the assistance of polar solvents, the two-dimensional material achieves highly selective wetting and adhesion within the overlapping window. During the separation process, the two-dimensional material undergoes self-limiting fracture strictly along the window boundary, effectively eliminating edge burrs and tearing phenomena in traditional transfer processes, and significantly improving the edge sharpness of the micropattern and the interfacial bonding strength.

[0020] 3. High process versatility and capability for complex geometric configurations: This invention provides a flexible selection path for positive / negative pattern modes, adaptable to target substrates with different wetting properties. Furthermore, this method breaks away from the limitations of traditional mask pattern replication, enabling the construction of complex topological structures that are difficult to achieve with conventional processes through the misaligned combination of simple geometric shapes, greatly expanding the application scope of two-dimensional material micro / nano fabrication. Attached Figure Description

[0021] Figure 1 A schematic diagram illustrating the formation process of a low surface energy background region on a target substrate, provided for a specific embodiment of the present invention, shows the formation of a uniform low surface energy background region on the surface of the target substrate, wherein... Figure 1 Figure 'a' shows the process of forming a uniform low surface energy background layer on the target substrate surface by spin-coating a fluoropolymer layer (Cytop). Figure 1 In the diagram, b represents the low surface energy background layer formed on the target substrate surface after spin coating; Figure 2 A schematic diagram of the "positive patterning" process of the substrate surface energy provided in a specific embodiment of the present invention, wherein, Figure 2 In this context, 'a' represents the target substrate pattern that already has a uniform low surface energy background region. Figure 2 In the diagram, b represents the state of the target substrate after selective surface activation treatment is performed after covering it with the second mask. Figure 2 In the image, 'c' represents the target substrate image that has undergone surface activation treatment but still covers the second mask. Figure 2 In this context, d represents the target substrate image with a differential surface energy pattern obtained after peeling off the second mask. Figure 3A schematic diagram illustrating the formation process of a high surface energy background region on a target substrate, provided in a specific embodiment of the present invention, shows the formation of a uniform high surface energy background region on the surface of the target substrate, wherein... Figure 3 In the diagram, 'a' represents the process of performing full-surface oxygen plasma treatment on the target substrate. Figure 3 In the diagram, b represents the high surface energy target region formed on the target substrate surface after spin coating; Figure 4 A schematic diagram of the substrate surface energy "depatching" process provided in a specific embodiment of the present invention, wherein, Figure 4 In the image, 'a' represents the target substrate map that already has a uniform high surface energy background region. Figure 4 In the diagram, b represents the state of the target substrate after selective surface hydrophobic treatment is performed after covering it with the second mask. Figure 4 In this context, 'c' represents the target substrate that has undergone surface hydrophobic treatment while still covering the second mask. Figure 4 In this context, d represents the target substrate image with a differential surface energy pattern obtained after peeling off the second mask. Figure 5 This is a schematic diagram of a two-dimensional material pre-patterning preparation process provided in a specific embodiment of the present invention, wherein, Figure 5 In the diagram, 'a' represents the patterning process of two-dimensional material in vacuum-assisted filtration under the confinement of the first mask. Figure 5 In the diagram, b represents the growth substrate—a porous filter membrane—carrying a two-dimensional material pre-pattern covering the first mask. Figure 6 This is a schematic diagram of the capillary-induced selective transfer process in this invention, wherein, Figure 6 Figure 'a' illustrates a flowchart of using the secondary scaling effect to overcome mask precision limitations and prepare high-resolution patterns. Figure 6 b in the diagram illustrates a flowchart of constructing complex micro / nano structures using locally overlapping windows; Figure 7 This is a schematic diagram illustrating the forming process of high-resolution two-dimensional material micropatterns in this invention. Figure 7 In the image, 'a' represents a two-dimensional material pre-pattern prepared using a mask-confined vacuum-assisted filtration process. Figure 7 In the image, b represents the target substrate map for which a surface energy difference pattern was constructed through surface processing; Figure 7 In the diagram, 'c' represents the result of feature size reduction or complex pattern transfer achieved using locally overlapping windows.

[0022] In the figure: 1. Target substrate, 2. Low surface energy background area, 3. Surface activation treatment, 4. Second mask, 5. High surface energy target area, 6. Second positioning mark, 7. MXene dispersion, 8. First mask, 9. MCE porous filter membrane, 10. Vacuum-assisted filtration device, 11. Two-dimensional material pre-pattern, 12. First positioning mark, 13. Two-dimensional material micro-pattern. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments, but the implementation of the present invention is not limited thereto.

[0024] This invention proposes a micro-nano fabrication strategy that breaks through the precision limits of physical masks. This method decouples the direct correspondence between "pattern definition" and "mask size," utilizing capillary forces induced by surface energy differences and a misalignment mechanism at the micro-nano scale to achieve a "secondary scaling down" of pattern feature sizes on the target substrate side. This enables a leapfrog manufacturing process from micrometer-scale masks to submicrometer-scale micropatterns.

[0025] A specific embodiment of the present invention provides a two-dimensional material patterning method based on mask-assisted filtration and displacement overlay transfer, comprising: (1) A patterned barrier layer is constructed on a porous filter membrane substrate using a first mask, and a mask-confined vacuum-assisted filtration process is used to filter and deposit the two-dimensional material dispersion. After removing the first mask, a two-dimensional material pre-pattern defined by the opening shape of the first mask is obtained on the porous filter membrane substrate.

[0026] (2) A local protective layer is formed on the target substrate using a second mask, and the substrate is surface modified to create a differentiated region with a significant surface energy gradient on the substrate surface. After removing the second mask, a surface-treated pattern is formed consisting of a hydrophilic high surface energy target region and a hydrophobic low surface energy background region.

[0027] (3) Flip the porous filter membrane substrate obtained in step (1) so that the side carrying the two-dimensional material faces the target substrate processed in step (2). Adjust the relative planar positions of the two to achieve misalignment and bonding, so that the two-dimensional material pre-pattern and the high surface energy target area only come into contact within a preset local overlap window. In this state, the capillary force induced by the surface energy difference is used to selectively transfer the two-dimensional material located within the local overlap window and firmly attach it to the high surface energy area of ​​the target substrate; while the two-dimensional material located in the non-overlapping area (corresponding to the low surface energy background) remains on the porous filter membrane. Subsequently, separate the porous filter membrane substrate, and the two-dimensional material undergoes self-limiting fracture along the boundary of the local overlap window, thereby achieving the overlay transfer of high-resolution micropatterns on the target substrate.

[0028] In one specific embodiment, the linewidth or feature size of the two-dimensional material micro-patterning provided in this embodiment is obtained by the geometric size of the locally overlapping window, which is smaller than the minimum feature size of the first mask or the second mask; the geometric size of the locally overlapping window is determined by the relative pose parameters of the two-dimensional material pre-pattern and the surface-treated pattern in the plane; the relative pose parameters include translation displacement, rotation angle and / or scale difference.

[0029] In one specific embodiment, the geometry of the partially overlapping window provided in this embodiment is defined by the overlapping area of ​​the two-dimensional material pre-pattern and the surface-treated pattern in the plane; the geometry includes linear, strip-shaped, ring-shaped, island-shaped or a combination thereof; in particular, when it is necessary to construct a ring-shaped micro-pattern, a circular two-dimensional material pre-pattern and a circular surface-treated pattern can be set respectively, and a ring structure can be formed by controlling the concentric or eccentric misalignment and overlap of the two in the plane using the principle of topological difference.

[0030] In one specific embodiment, the method of constructing the surface energy difference region in step (2) of the present invention adopts a "positive pattern pattern", including: First, a hydrophobic layer is formed on the surface of the target substrate, wherein the hydrophobic layer is a hydrophobic monolayer and / or a hydrophobic polymer layer. After covering the second mask, the exposed area of ​​the second mask is subjected to surface activation treatment to remove the hydrophobic material in the exposed area and / or to oxidize and modify it and introduce hydrophilic groups, thereby forming a hydrophilic high surface energy target area in the exposed area. The formed high surface energy target area is the pattern after surface treatment, while the area covered by the second mask remains a hydrophobic low surface energy background area.

[0031] This invention utilizes the high surface energy target area formed by the above-mentioned positive pattern pattern as a "liquid adhesive" or "capillary adhesive". When the surface-treated pattern is misaligned and bonded with the two-dimensional material pre-pattern, due to its hydrophilicity, it can "paste" and transfer the two-dimensional material located in the partially overlapping window of the pre-pattern to the target substrate through interfacial interaction, while the hydrophobic background area does not adhere, thereby completing a highly selective two-dimensional material transfer, and the size of the transferred pattern is smaller than the original size of the first and second masks.

[0032] In one specific embodiment, the surface activation treatment provided in this embodiment is oxygen plasma (O2 Plasma) or ultraviolet ozone (UV-Ozone) treatment, and can be replaced by corona treatment, ozone oxidation, excimer laser irradiation or other equivalent surface activation treatments.

[0033] In one specific embodiment, the hydrophobic self-assembled monolayers (SAMs) provided in this embodiment include alkylsilanes, fluorosilanes, or combinations thereof; the hydrophobic polymer layer includes fluoropolymers and / or siloxane polymers.

[0034] In one specific embodiment, the method of constructing the surface energy difference region in step (2) of the present invention adopts an "inverse patterning mode", including: First, a hydrophilic layer or an activatable layer is formed on the surface of the target substrate; After covering the second mask, the exposed area of ​​the second mask is hydrophobically treated, transforming it into a hydrophobic, low-surface-energy background area. In this mode, the formed low-surface-energy background area constitutes the background, while the area masked by the second mask remains a hydrophilic, high-surface-energy target area. In the subsequent misalignment and bonding step, the high-surface-energy area retained by the masking is overlapped with the two-dimensional material pre-pattern to achieve transfer.

[0035] Specifically, this invention utilizes a combination of "inverse pattern mode" or "positive pattern mode" and a misalignment alignment strategy to overcome the limitations of mask shape and construct special topological structures. Specifically, when both the two-dimensional material pre-pattern and the surface-treated pattern are circular, and the diameter of the two-dimensional material pre-pattern is larger than the diameter of the surface-treated pattern, the two-dimensional material pre-pattern on the porous filter membrane substrate is misaligned and aligned with the surface-treated pattern on the target substrate, so that the surface-treated pattern is completely or partially located inside the two-dimensional material pre-pattern. At this time, through the interfacial bonding effect of the hydrophilic high surface energy target region, the two-dimensional material is transferred only within a local overlapping window on the target substrate, thereby forming a ring-shaped or other complex geometric two-dimensional material micro-pattern.

[0036] Specifically, to enhance the transfer effect, before or during the bonding process of misaligning and aligning the two-dimensional material pre-pattern on the porous filter membrane substrate obtained in step (1) with the surface energy differential pattern on the target substrate obtained in step (2), a mist or vapor of polar solvent is introduced at the bonding interface. This polar solvent preferentially wets the patterned area (high surface energy area) after surface treatment and forms micron-sized capillary bridges, thereby enhancing the capillary driving force and interface adhesion strength within the local overlap window and inhibiting the wetting and adhesion of the hydrophobic low surface energy background area, thus significantly improving the transfer selectivity and pattern edge quality.

[0037] The two-dimensional material described in step (1) of the specific embodiment of the present invention includes one or more combinations of MXene, graphene, graphene oxide (GO), molybdenum disulfide (MoS2) and other transition metal chalcogenides (TMDs), black phosphorus, or hexagonal boron nitride (h-BN); the concentration of the dispersion is controlled between 0.01 mg / mL and 1 mg / mL.

[0038] The solvent of the two-dimensional material dispersion provided in the specific embodiments of the present invention is a polar solvent or a mixed solvent containing polar components. The static contact angle of the solvent in the high surface energy target region is not greater than 30°, and the static contact angle in the hydrophobic low surface energy background region is not less than 70°. This ensures that spatially selective wetting behavior is formed in step (3).

[0039] In a specific embodiment of the present invention, both the first and second photomasks are designed with auxiliary positioning marks. The first and second positioning marks are formed on the porous filter membrane substrate and the target substrate, respectively, by photolithography.

[0040] In the misalignment and bonding process of step (3), under the observation of the micro-optical system, the relative position of the porous filter membrane and the target substrate is first adjusted so that the two-dimensional material pre-pattern layer and the target substrate pattern can be initially aligned over a large range.

[0041] Based on the initial alignment, further fine alignment is achieved by observing and using a high-precision displacement stage to quantitatively control the relative displacement and adjust the relative position of the first positioning mark and the second positioning mark. This enables controllable adjustment of the geometric width of the locally overlapping window and continuous adjustable control of the micro-pattern resolution.

[0042] The separation method in step (3) provided in the specific embodiment of the present invention includes tangential shear peeling, rolling peeling or peeling with a set peeling angle, so as to introduce shear force components, cause the two-dimensional material to break at the boundary of the local overlapping window, and reduce edge burrs.

[0043] The present invention provides at least one of the following methods for treating the target substrate after obtaining the two-dimensional material micropattern: thermal annealing, solvent cleaning, vacuum drying, or mild plasma treatment, in order to remove interface residues and enhance the bonding between the two-dimensional material and the target substrate.

[0044] Example 1: Fabrication of a graphene field-effect transistor (GFET) based on the present invention. This example utilizes the method provided by the present invention to fabricate a GFET device with a 1 μm short channel. It includes: Device structure: A heavily doped Si substrate is used as the back gate, with SiO2 on it as the gate dielectric; MXene patterns are formed on the SiO2 surface as the source / drain electrodes; a continuous graphene film obtained by chemical vapor deposition (CVD) is transferred above the source / drain electrodes as a semiconductor channel layer, and the graphene spans the source / drain gap and forms in-plane contacts with the source / drain. Specific steps are as follows: Step 1: Preparation of Target Substrate 1 and Gate Dielectric. A heavily doped Si / SiO2 wafer is selected as target substrate 1, where Si is used as the back gate electrode and SiO2 is used as the gate dielectric. Target substrate 1 is sequentially cleaned with acetone and isopropanol and dried with nitrogen gas for later use.

[0045] Step 2: High-resolution selective transfer fabrication of MXene source and drain electrodes (achieving 1 μm effective feature) (1) Preparation of MXene dispersion 7: The commercial 10 mg / mL MXene dispersion 7 was diluted with deionized water to make the mass concentration of MXene dispersion 7 0.1 mg / mL; then the diluted MXene dispersion 7 was ultrasonically dispersed for 10 min (to obtain a uniform and stable dispersion system) for later use.

[0046] (2) such as Figure 1 As shown in a and b, the surface energy patterning of the target substrate 1 is achieved by spin-coating a fluoropolymer layer (Cytop) to first form a uniform low surface energy background region 2 on the surface of the target substrate 1. Figure 2 As shown in a, b, c, and d, the second mask 4 is made of a polyimide (PI) film with a thickness of 50 μm. Source / drain electrode pattern openings and a second positioning mark 6 are fabricated on the PI film using photolithography, wherein the minimum feature size of the source / drain electrode pattern is 5 μm. After attaching the second mask to the surface of the target substrate 1, a surface activation treatment 3 is applied to the exposed area, transforming it from a low surface energy state to a high surface energy target area 5, while the area covered by the second mask 4 remains a low surface energy background area 2.

[0047] In this embodiment, surface activation treatment 3 uses oxygen plasma treatment: oxygen flow rate 30 sccm, chamber pressure 80 Pa, radio frequency power 60 W, and treatment time 45 s. After treatment, the second mask is peeled off to obtain a surface energy differential pattern for selective transfer of source and drain electrodes.

[0048] (3) such as Figure 5 As shown in Figure a, the two-dimensional material pre-pattern 11 of the MXene source and drain electrodes is prepared: a porous MCE (Mixed Cellulose Ester) membrane 9 with a pore size of 0.2 μm is provided as the growth substrate. The first mask 8 is also prepared using a PI film, but to improve adhesion compliance and reduce gaps, the PI film thickness of the first mask 8 is 5 μm; patterned openings and first positioning marks 12 with the same or equivalent as the source and drain electrodes are processed on the first mask 8 by photolithography, wherein the minimum feature size is 5 μm.

[0049] like Figure 5 As shown in b, the first mask 8 is attached to the 0.2 μm pore size MCE porous filter membrane 9, and the MXene dispersion 7 obtained in step 2 (1) is filtered and deposited using a vacuum-assisted filtration device 10, so that MXene is deposited on the surface of the MCE porous filter membrane 9 to form a two-dimensional material pre-pattern 11, and then the second mask is peeled off.

[0050] (4) Misalignment to form a local overlapping window: Flip the MCE porous filter membrane 9 carrying the two-dimensional material pre-pattern 11 so that the MXene surface faces the surface energy patterned target substrate 1 obtained in step 2; Under microscopic observation, make the second positioning mark 6 coincide with the first positioning mark 12.

[0051] In this embodiment, the relative positions of the second positioning mark 6 and the first positioning mark 12 in their respective patterns are pre-designed to be offset by 4 μm, so that when the positioning marks are aligned, the two-dimensional material pre-pattern 11 and the high surface energy drain region of the target substrate 1 form a local overlap window with a width of 1 μm only in the plane; the local overlap window is used to limit the effective feature size of the source and drain electrodes to 1 μm.

[0052] (5) Capillary-induced selective transfer: The MCE porous membrane 9 is made into conformal contact with the target substrate 1; under the selective wetting conditions induced by surface energy difference, deionized water mist is introduced into the interface between the MCE porous membrane 9 and the target substrate 1, so that the high surface energy target region 5 is preferentially wetted and forms a capillary liquid bridge. Under capillary induction, MXene is selectively transferred and attached only within the 1 μm local overlap window; MXene located in the non-overlap region remains in the MCE porous membrane 9 without transfer. Subsequently, the MCE porous membrane 9 and the target substrate 1 are separated to obtain a two-dimensional material micropattern 13 of MXene source and drain patterns, such as Figure 6 As shown in 'a'.

[0053] (6) Post-processing: After obtaining the two-dimensional material micropattern 13 of MXene source and drain patterns, the target substrate 1 is immediately subjected to a drying and fixation treatment to remove residual moisture and improve electrode adhesion stability: the target substrate 1 is placed in a vacuum oven or vacuum hot stage and dried at 60 °C for 90 min to remove residual deionized water and promote the drying and fixation of the two-dimensional material micropattern 13 of MXene source and drain patterns.

[0054] Example 2: Fabrication of Toroidal Micro Supercapacitor (MSC) Electrode Based on Topological Recombination Strategy. This example aims to demonstrate the ability of the present invention to construct complex geometric topologies using simple pre-patterns (see attached specification). Figure 6 (b) This solves the problem that traditional vacuum filtration processes cannot directly prepare complex patterns such as rings and suspensions on porous filter membranes.

[0055] Device structure design: Concentric ring-shaped MXene microelectrodes were fabricated for in-plane micro supercapacitors. The structure consists of an inner circular electrode and an outer ring electrode, separated by a micrometer-level gap.

[0056] The specific steps are as follows: Step 1: Global hydrophilication of the target substrate: A silicon wafer (Si / SiO2) with a 300 nm oxide layer on its surface is selected as the target substrate 1. For example... Figure 3 As shown in a and b, the target substrate 1 underwent full-surface oxygen plasma (O2Plasma) treatment (60W power, 60s time). After treatment, the entire surface of the target substrate was activated, forming a uniform hydrophilic high surface energy target region (contact angle <5°).

[0057] Step 2: Construct a central hydrophobic differential pattern: (1) Second mask design: Design a second mask 4, which includes a circular opening with a diameter of 20 μm (used to define the inner diameter of the ring), and the rest is a solid occlusion area.

[0058] (2) Concealing and hydrophobicity: such as Figure 4 As shown in a, b, and c, the second mask 4 is applied over the fully hydrophilic target substrate obtained in step 1. At this point, a 20 μm circular region at the center of the substrate is exposed, while the surrounding area is protected by the mask. Subsequently, a hydrophobic monolayer (such as PFDS) is sprayed or vapor-deposited onto the exposed area.

[0059] (3) Results: such as Figure 4 As shown in d, after removing the second mask 4, a hydrophobic low surface energy circular region (i.e., "hydrophobic island") with a diameter of 20 μm is formed on the target substrate, while the background outside the circular region remains in a hydrophilic high surface energy state.

[0060] Step 3: Fabrication of a large-size solid circular pre-pattern: Design the first mask 8, which contains a solid circular opening with a diameter of 30 μm. (e.g., ...) Figure 5 As shown in Figure a, the first mask 8 is attached to the MCE porous filter membrane 9, and the MXene dispersion is filtered by vacuum filtration. Figure 5 As shown in b, after removing the first mask, a two-dimensional material pre-pattern 11 with a diameter of 30 μm is obtained on the porous filter membrane.

[0061] Step 4: As Figure 7As shown in a, b, and c, the process involves misalignment and "hollow" transfer: a filter membrane carrying a 30 μm circular MXene pre-pattern is flipped and misaligned with the target substrate. The position is adjusted so that the 30 μm solid circular pattern on the filter membrane is concentrically aligned with the 20 μm hydrophobic circular region on the substrate. At this point, water mist is introduced into the interface to induce capillary liquid bridges. Due to the spatial difference in substrate wettability, the central hydrophobic region (d < 20 μm) inhibits liquid bridge formation, preventing MXene adhesion; while the peripheral hydrophilic region (20 μm < d < 30 μm) forms strong capillary adhesion with the MXene. Finally, the porous filter membrane is peeled off. The MXene undergoes self-limiting fracture at the boundary of the hydrophobic islands (i.e., at a diameter of 20 μm). The central portion of the MXene remains on the filter membrane, while the peripheral annular portion is successfully transferred to the target substrate, thus obtaining a two-dimensional material micropattern 13 with an inner diameter of 20 μm and an outer diameter of 30 μm of MXene annular micropatterns on the target substrate.

Claims

1. A two-dimensional material patterning method based on mask-assisted filtration and displacement overlay transfer, characterized in that, include: (1) A patterned barrier layer is constructed on a porous filter membrane substrate using a first mask, and two-dimensional material is deposited in a defined area by vacuum-assisted filtration. After removing the first mask, a two-dimensional material pre-pattern is formed. (2) A local protective layer is formed on the target substrate using a second mask and surface treatment is performed. A surface energy difference region is constructed on the substrate surface. After removing the second mask, a surface treatment pattern is obtained. The surface treatment pattern includes a hydrophilic high surface energy target region and a hydrophobic low surface energy background region. (3) The porous filter membrane substrate obtained in step (1) is flipped and misaligned with the target substrate after step (2) to form a local overlapping window between the two-dimensional material pre-pattern and the high surface energy target area; the capillary force induced by the surface energy difference is used to selectively transfer the two-dimensional material in the overlapping window to the target substrate, while the non-overlapping part is retained on the porous filter membrane substrate; then the porous filter membrane substrate is separated, and the two-dimensional material is broken at the boundary of the local overlapping window, thereby realizing overlay transfer on the target substrate and obtaining a high-resolution two-dimensional material micro-pattern defined by the local overlapping window.

2. The two-dimensional material patterning method based on mask-assisted filtration and displacement overlay transfer according to claim 1, characterized in that, The linewidth or feature size of the two-dimensional material micropatterning is determined by the geometric size of the locally overlapping window, which is smaller than the minimum feature size of the first mask or the second mask; The geometric dimensions of the locally overlapping window are determined by the relative pose parameters of the two-dimensional material pre-pattern and the surface-treated pattern in the plane; The relative pose parameters include translational displacement, rotation angle, and / or scale difference.

3. The two-dimensional material patterning method based on mask-assisted filtration and displacement overlay transfer according to claim 1, characterized in that, The geometry of the partially overlapping window is defined by the overlapping area in the plane of the two-dimensional material pre-pattern and the surface-treated pattern; The geometric shapes include linear, strip-shaped, ring-shaped, island-shaped, or combinations thereof; Wherein, when the geometric shape is ring-shaped, the geometric shape is formed by the staggered overlap of a first circular pattern and a second circular pattern.

4. The two-dimensional material patterning method based on mask-assisted filtration and displacement overlay transfer according to claim 1, characterized in that, The method for constructing the surface energy difference region in step (2) is a positive pattern pattern, specifically including: First, a hydrophobic layer is formed on the surface of the target substrate, wherein the hydrophobic layer is a hydrophobic monolayer and / or a hydrophobic polymer layer. After covering the second mask, the exposed area of ​​the second mask is subjected to surface activation treatment to remove the hydrophobic material in the exposed area and / or to oxidize and modify it to introduce hydrophilic groups, thereby transforming the exposed area into a hydrophilic high surface energy target area, while the area covered by the second mask remains a hydrophobic low surface energy background area.

5. The two-dimensional material patterning method based on mask-assisted filtration and displacement overlay transfer according to claim 1, characterized in that, The method for constructing the surface energy difference region in step (2) is an inverse patterning mode, specifically including: First, a hydrophilic layer or an activatable layer is formed on the surface of the target substrate; After covering the second mask, the exposed area of ​​the second mask is hydrophobically treated to form a hydrophobic low surface energy background area. The low surface energy background area is the pattern after surface treatment, while the area covered by the second mask remains a hydrophilic high surface energy target area.

6. The two-dimensional material patterning method based on mask-assisted filtration and displacement overlay transfer according to claim 1, characterized in that, Before or during the bonding process of misaligning and aligning the two-dimensional material pre-pattern on the porous filter membrane substrate obtained in step (1) with the surface energy differential pattern on the target substrate obtained in step (2), polar solvent mist or vapor is introduced at the bonding position so that the polar solvent preferentially wets the pattern area after surface treatment and forms a capillary bridge, thereby enhancing the capillary driving force and interface fixation strength in the local overlapping window and inhibiting the wetting and adhesion of the hydrophobic low surface energy background area, thereby improving the transfer selectivity and pattern edge quality.

7. The two-dimensional material patterning method based on mask-assisted filtration and displacement overlay transfer according to claim 1, characterized in that, The solvent of the two-dimensional material dispersion is a polar solvent or a mixed solvent containing polar components. The static contact angle of the solvent in the high surface energy target region is not greater than 30°, and the static contact angle in the hydrophobic low surface energy background region is not less than 70°.

8. The two-dimensional material patterning method based on mask-assisted filtration and displacement overlay transfer according to claim 1, characterized in that, Both the first and second masks are designed with auxiliary positioning marks, thereby forming the first positioning mark and the second positioning mark on the porous filter membrane substrate and the target substrate, respectively. In the misalignment and bonding process of step (3), under the observation of the micro-optical system, the relative position of the plane between the porous filter membrane substrate and the target substrate is first adjusted so that the two-dimensional material pre-pattern layer and the target substrate pattern can be initially aligned over a large range. Based on the initial alignment, the relative displacement is further quantitatively controlled by observation and in conjunction with a high-precision displacement stage. The relative positions of the first positioning mark and the second positioning mark are adjusted for fine alignment, thereby achieving controllable adjustment of the geometric width of the locally overlapping window and continuous adjustable control of the micro-pattern resolution.

9. The two-dimensional material patterning method based on mask-assisted filtration and displacement overlay transfer according to claim 1, characterized in that, The separation method in step (3) includes tangential shear peeling, rolling peeling, or peeling with a set peeling angle to introduce shear force components, causing the two-dimensional material to break at the boundary of the local overlapping window and reducing edge burrs.

10. The two-dimensional material patterning method based on mask-assisted filtration and displacement overlay transfer according to claim 1, characterized in that, The target substrate after obtaining the two-dimensional material micropattern is subjected to at least one of the following treatments: thermal annealing, solvent cleaning, vacuum drying, or mild plasma treatment, in order to remove interfacial residues and enhance the bonding between the two-dimensional material and the target substrate.

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