A method for batch dry transfer of two-dimensional materials based on pvdc
By using PVDC/PDMS micro-dot stamp arrays and tungsten needle array spotting methods, the problems of low transfer efficiency and high temperature of two-dimensional materials were solved, realizing efficient, low-temperature batch transfer and precise preparation of two-dimensional materials.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANGHAI INST OF MICROSYSTEM & INFORMATION TECH CHINESE ACAD OF SCI
- Filing Date
- 2026-02-02
- Publication Date
- 2026-06-05
AI Technical Summary
Existing two-dimensional material transfer methods are inefficient and cannot meet the requirements for mass production of large-scale integrated circuits. Furthermore, the high operating temperature can easily damage heat-sensitive materials, and the material preparation process is uncontrollable.
A PVDC/PDMS micro-dome stamp array combined with a tungsten needle array spotting method was adopted to batch transfer two-dimensional materials by using the electrostatic adsorption force of PVDC at room temperature and releasing them to the target substrate at low temperature.
It enables efficient batch transfer of two-dimensional materials, reduces operating temperature, improves transfer accuracy and efficiency, and protects the intrinsic properties of the materials.
Smart Images
Figure CN122161423A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of two-dimensional material preparation and micro / nano fabrication technology, and specifically relates to a method for batch dry transfer of two-dimensional materials based on PVDC. Background Technology
[0002] With the deepening research on two-dimensional materials, devices based on van der Waals heterostructures (vdW heterostructures) are increasingly widely used. Current fabrication processes mainly rely on polymer-assisted dry transfer techniques, such as using polycarbonate (PC), polymethyl methacrylate (PMMA), or polyvinyl chloride (PVC) as dielectrics. However, existing technologies generally suffer from the following limitations:
[0003] (1) Inefficient: Traditional transfer methods are mostly based on single-point operation, which can only fabricate one device at a time, and cannot meet the needs of large-scale integrated circuits for batch fabrication.
[0004] (2) High operating temperature: Existing PVC or PC methods usually require high pick-up temperature (>70℃) and release temperature (>130℃), which can easily damage heat-sensitive materials or introduce thermal stress.
[0005] (3) Uncontrollable material preparation: Existing PVC methods mostly use commercial plastic wrap directly. Its composition is complex and the film thickness is difficult to control precisely through spin coating process, which limits the improvement of transfer accuracy.
[0006] Therefore, developing a two-dimensional material transfer method that enables low-temperature, high-efficiency, and batch operations is an urgent need for current technological development. Summary of the Invention
[0007] The technical problem to be solved by the present invention is to provide a method for batch dry transfer of two-dimensional materials based on PVDC, so as to improve transfer efficiency, reduce operating temperature and improve transfer accuracy.
[0008] This invention provides a method for batch dry transfer of two-dimensional materials based on PVDC, comprising the following steps:
[0009] S1. PDMS micro-dot arrays were prepared using a multi-level tungsten needle array spotting method;
[0010] S2. Surface activation of the PDMS micro-dot array;
[0011] S3. The prepared PVDC-based polymer solution is dropped onto the surface of the PDMS micro dome array, and a coating film is formed using a spin coater. After curing, a PVDC film is formed on the PDMS surface, thereby obtaining a PVDC / PDMS stamp array.
[0012] S4. Using a PVDC / PDMS stamp array, batch pick up two-dimensional materials pre-prepared on the substrate to form a multilayer heterojunction array on the PVDC / PDMS stamp array;
[0013] S5. Release the PVDC / PDMS stamp array with adsorbed multilayer heterojunction array onto the target substrate, thereby completing the batch transfer of two-dimensional materials.
[0014] Preferably, step S1 specifically includes:
[0015] (a) Using an array of tungsten needles with a tip diameter of 250~350 μm, the PDMS mixture is dipped into the liquid. The liquid droplet array is then applied to a clean glass slide using a motor-driven lifting arm. The slide is then cured on a heating stage at 130~140 ℃ for 5~10 min to form a bottom micro-dot array.
[0016] (b) Use a tungsten needle array with a tip diameter of 20~30 μm to dip into the mixture, accurately aim at the center of the first layer dome and spot it, and cure it at 130~140 ℃ for 5~10 min;
[0017] (c) Use a tungsten needle array with a tip diameter of 200~300 nm to dip into the mixture, spot a small amount of the mixture on the second dome, and then cure it again at 130~140 ℃ for 5~10 min.
[0018] Preferably, the preparation method of the PDMS mixture in step (a) of step S2 is as follows: the PDMS main agent and the curing agent are mixed and stirred at a mass ratio of 10:1, and after stirring evenly, the mixture is placed in a vacuum drying oven to remove air bubbles, thereby obtaining the PDMS mixture.
[0019] Furthermore, the PDMS main agent and curing agent are derived from commercially available Sylgard 184 silicone elastomer.
[0020] Preferably, the surface activation in step S2 specifically involves placing the PDMS array in an oxygen plasma cleaner for surface treatment, with a working pressure of 10 Pa, an RF power of 100~150 W, and a treatment time of 10~20 min, to enhance the adhesion of the subsequent PVDC film.
[0021] Preferably, the preparation of the PVDC-based polymer solution in step S3 is as follows: PVDC resin powder is selected, the composition of which is a copolymer of vinylidene chloride and vinyl chloride, with a mass ratio of 87%:13%. This ratio ensures that the film has good flexibility and adhesion. The PVDC resin powder is dissolved in tetrahydrofuran (THF) to prepare a PVDC solution with a mass fraction of 10 wt%, and stirred in a sealed container until completely dissolved.
[0022] Preferably, the spin coating parameters in step S3 are: a rotation speed of 1000 r / min; the curing process is: after spin coating, the film is placed on an 80 ℃ heating table and baked for 15~20 min to remove the solvent; the thickness of the PVDC film is 10~20 μm.
[0023] Preferably, the batch picking in step S4 specifically involves:
[0024] The PVDC / PDMS stamp array was mounted on a transfer platform, and the stage temperature was set to 15~30 ℃. The PVDC / PDMS stamp array was lowered so that the micro dome contacted the two-dimensional material array on the substrate. After contact, the PVDC / PDMS stamp array was rapidly lifted at a speed of 200~500 μm / s. Utilizing the strong adhesion of PVDC at room temperature, the two-dimensional material was peeled off from the original substrate in batches and adsorbed onto the surface of the PVDC / PDMS stamp array.
[0025] Repeat the same operation, using the interlayer van der Waals forces and the auxiliary effect of PVDC, to pick up other two-dimensional materials in sequence, forming a two-dimensional material stack structure, and finally forming a multilayer heterojunction array on the PVDC / PDMS stamp array.
[0026] Preferably, the release process in step S5 specifically involves: moving the PVDC / PDMS stamp array with the adsorbed multilayer heterojunction array above the target substrate, and bringing the two-dimensional material at the bottom of the multilayer heterojunction array into contact with the target substrate; turning on the heating stage and setting the temperature to 60~70 ℃, causing the PVDC film to soften thermally and significantly reducing the adhesion force; slowly lifting the PVDC / PDMS stamp array at a speed of 10~20 μm / s, since the bonding force between PVDC and the two-dimensional material is less than the bonding force between the two-dimensional material and the substrate and between the two-dimensional material layers, the multilayer heterojunction array is completely released onto the target substrate, thereby completing the batch transfer of the two-dimensional material.
[0027] Beneficial effects
[0028] (1) Array-based batch transfer design: This invention designs and fabricates a PVDC / PDMS micro dome stamp array, which, combined with a tungsten needle array spotting process, enables the batch picking and stacking of two-dimensional material devices, significantly improving the fabrication efficiency.
[0029] (2) Self-made PVDC functional layer: The present invention uses a self-prepared solution of PVDC resin in a specific ratio (87%:13%) to spin-coat a film, replacing commercial plastic wrap. The PVDC film has a high-density dichloride atom (-CCl2-) structure, which provides extremely strong electrostatic adsorption force, allowing the pickup operation to be completed at room temperature.
[0030] (3) Optimized low-temperature process window: The process parameters determined by this invention (pick-up 15~30℃, release 60~70℃) are much lower than those of the prior art, which effectively protects the intrinsic properties of the material and the process window is stable. Attached Figure Description
[0031] Figure 1 This is a schematic diagram of the fabrication process of the PVDC / PDMS stamp array in Embodiment 1 of the present invention (taking a single stamp as an example).
[0032] Figure 2 This is a schematic diagram of the 10x10 PVDC / PDMS stamp array in Embodiment 1 of the present invention.
[0033] Figure 3 This is a schematic diagram of the process of transferring the three-layer heterogeneous structure A / B / C using a PVDC / PDMS stamp array in Embodiment 1 of the present invention (taking a single stamp as an example). Detailed Implementation
[0034] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.
[0035] Example 1
[0036] This embodiment utilizes a PVDC / PDMS stamp array to achieve batch dry transfer of a three-layer heterostructure A / B / C. It mainly includes the fabrication of the PVDC / PDMS stamp array and the batch pickup and transfer of two-dimensional materials, specifically comprising the following steps:
[0037] Part 1: Fabrication of PVDC / PDMS stamp arrays
[0038] S1. Fabrication of PDMS micro-dot array: such as Figure 1 As shown, commercially available Sylgard 184 silicone elastomer was selected. PDMS main agent and curing agent were mixed at a mass ratio of 10:1, stirred evenly, and then placed in a vacuum drying oven to remove air bubbles, thus obtaining a PDMS mixture. A hierarchical micro-dot structure (taking a single stamp as an example) was prepared using a multi-level tungsten needle array spotting method.
[0039] (a) Preparation of the first layer: Using an array of tungsten needles with a tip diameter of about 300 μm, the PDMS mixture was dipped into the liquid. The liquid droplet array was then applied to the clean glass slide surface using a motor-driven lifting arm. The slide was cured on a heating stage at 130 °C for 5 min to form a bottom micro-dot array.
[0040] (b) Preparation of the second layer: Using an array of tungsten needles with a tip diameter of about 25 μm, dip the mixture into the solution and accurately spot it at the center of the first layer dome. Then cure it at 130°C for 5 min.
[0041] (c) Preparation of the third layer: Using an array of tungsten needles with a tip diameter of about 200 nm, the mixture was dipped and a small amount was spotted on the dome of the second layer, and then cured again at 130 °C for 5 min.
[0042] Through the above steps, a 10x10 PDMS array was prepared on a glass slide, with a center-to-center spacing of 1 mm between adjacent stamps (reference). Figure 2 Each unit has a contact surface with a very small radius of curvature (approximately 30 μm in diameter) at its top.
[0043] (d) PDMS surface activation: The prepared PDMS array was placed in an oxygen plasma cleaner for surface treatment. The working pressure was 10 Pa, the RF power was 100 W, and the treatment time was 10 min to enhance the adhesion of the subsequent PVDC film.
[0044] (e)-(f) Spin-coating and curing of PVDC films: PVDC resin powder was selected, its composition being a copolymer of vinylidene chloride and vinyl chloride at a mass ratio of 87%:13%. This ratio ensured that the film had good flexibility and adhesion. The PVDC resin powder was dissolved in tetrahydrofuran solvent to prepare a 10 wt% PVDC solution, which was then stirred in a sealed container until completely dissolved. The PVDC solution was dropped onto the surface of an activated PDMS stamp array, and a spin coater was used for coating at a speed of 1000 r / min. After spin coating, the film was placed on an 80 ℃ heating table and baked for 15 min to remove the solvent.
[0045] Finally, a PVDC film with a thickness of approximately 10 μm was formed on the PDMS surface, resulting in a 10x10 PVDC / PDMS stamp array, as shown below. Figure 2 As shown.
[0046] Part Two: Batch Pick-up and Transfer of Two-Dimensional Materials
[0047] S2. For example Figure 3 As shown, a PVDC / PDMS stamp array is used to batch pick up two-dimensional materials A, B, and C that have been pre-prepared on a SiO2 / Si substrate.
[0048] (a)-(b) Picking up Material A: The stamp array is mounted on the transfer platform, and the stage temperature is set to 25°C. The stamp array is lowered to bring the micro-dots into contact with the Material A array on the substrate. After contact, the stamps are rapidly lifted at a speed of 500 μm / s. Utilizing the strong adhesion of PVDC at room temperature, Material A is peeled off from the source substrate in batches and adsorbed onto the stamp surface.
[0049] (c)-(d) Picking up material B: Maintaining the temperature at 25°C, align the stamp with material A adsorbed onto the array of material B on the substrate. After contact, lift it up rapidly at a speed of 500 μm / s, and pick up material B using the interlayer van der Waals forces and the assisted action of PVDC to form an A / B stacked structure.
[0050] Material C pickup: Repeat the above steps to pickup material C at 25°C, ultimately forming a three-layer heterojunction array A / B / C on the stamp. Figure 3 (Illustration of this step omitted)
[0051] (e)-(f) The stamp array with the adsorbed A / B / C heterojunction array is moved above the target substrate, and the stamp is lowered to bring the material into contact with the target substrate; the heating stage is turned on and the temperature is raised to 65 °C. At this temperature, the PVDC film is thermally softened and the adhesion is significantly reduced; the stamp is slowly raised at a speed of 10 μm / s. Since the bonding force between PVDC and the material is less than the bonding force between the material and the substrate and between material layers, the A / B / C heterojunction array is completely released onto the target substrate, completing the batch transfer.
[0052] This invention utilizes the excellent electrostatic adsorption properties and arrayed structure of PVDC materials to batch pick up two-dimensional materials at a relatively high speed (200~500 μm / s) at room temperature (15~30℃) and achieve batch release at a slower speed (10~20 μm / s) at a lower temperature (60~70℃). This method has advantages such as low operating temperature, high yield, and clean interface, enabling efficient batch assembly of van der Waals heterojunctions.
Claims
1. A method for batch dry transfer of two-dimensional materials based on PVDC, comprising the following steps: S1. PDMS micro-dot arrays were prepared using a multi-level tungsten needle array spotting method; S2. Surface activation of the PDMS micro-dot array; S3. The prepared PVDC-based polymer solution is dropped onto the surface of the PDMS micro dome array, and a coating film is formed using a spin coater. After curing, a PVDC film is formed on the PDMS surface, thereby obtaining a PVDC / PDMS stamp array. S4. Using a PVDC / PDMS stamp array, batch pick up two-dimensional materials pre-prepared on the substrate to form a multilayer heterojunction array on the PVDC / PDMS stamp array; S5. Release the PVDC / PDMS stamp array with adsorbed multilayer heterojunction array onto the target substrate, thereby completing the batch transfer of two-dimensional materials.
2. The method according to claim 1, characterized in that, Step S1 specifically includes: (a) Using an array of tungsten needles with a tip diameter of 250~350 μm, the PDMS mixture is dipped into the liquid. The liquid droplet array is then applied to a clean glass slide using a motor-driven lifting arm. The slide is then cured on a heating stage at 130~140 ℃ for 5~10 min to form a bottom micro-dot array. (b) Use a tungsten needle array with a tip diameter of 20~30 μm to dip into the mixture, accurately aim at the center of the first layer dome and spot it, and cure it at 130~140 ℃ for 5~10 min; (c) Use a tungsten needle array with a tip diameter of 200~300 nm to dip into the mixture, spot a small amount of the mixture on the second dome, and then cure it again at 130~140 ℃ for 5~10 min.
3. The method according to claim 2, characterized in that, The preparation method of the PDMS mixture in step (a) of step S2 is as follows: the PDMS main agent and the curing agent are mixed and stirred at a mass ratio of 10:
1. After stirring evenly, the mixture is placed in a vacuum drying oven to remove air bubbles, thereby obtaining the PDMS mixture.
4. The method according to claim 1, characterized in that, The surface activation in step S2 specifically involves placing the PDMS array in an oxygen plasma cleaner for surface treatment, with a working pressure of 10 Pa, an RF power of 100~150 W, and a treatment time of 10~20 min.
5. The method according to claim 1, characterized in that, The preparation of the PVDC-based polymer solution in step S3 is as follows: Select PVDC resin powder, the composition of which is a copolymer of vinylidene chloride and vinyl chloride, with a mass ratio of 87%:13%; Dissolve the PVDC resin powder in tetrahydrofuran to prepare a PVDC solution with a mass fraction of 10 wt%, and stir in a sealed container until completely dissolved.
6. The method according to claim 1, characterized in that, The spin coating parameters in step S3 are: rotation speed 1000 r / min; the curing process is: after spin coating, place on an 80 ℃ heating table and bake for 15~20 min to remove solvent; the thickness of the PVDC film is 10~20 μm.
7. The method according to claim 1, characterized in that, The batch picking in step S4 specifically involves: mounting the PVDC / PDMS stamp array on the transfer platform and setting the stage temperature to 15~30 ℃; controlling the PVDC / PDMS stamp array to descend so that the micro dome contacts the two-dimensional material array on the substrate; after contact, rapidly lifting the PVDC / PDMS stamp array at a speed of 200~500 μm / s, so that the two-dimensional material is peeled off from the original substrate in batches and adsorbed onto the surface of the PVDC / PDMS stamp array; Repeat the same operation, using the interlayer van der Waals forces and the auxiliary effect of PVDC, to pick up other two-dimensional materials in sequence, forming a two-dimensional material stack structure, and finally forming a multilayer heterojunction array on the PVDC / PDMS stamp array.
8. The method according to claim 1, characterized in that, The release process in step S5 is as follows: the PVDC / PDMS stamp array with the adsorbed multilayer heterojunction array is moved above the target substrate, so that the two-dimensional material at the bottom of the multilayer heterojunction array comes into contact with the target substrate; the heating stage is turned on and the temperature is set to 60~70 ℃, and the PVDC film is thermally softened; the PVDC / PDMS stamp array is slowly lifted at a speed of 10~20 μm / s, and the multilayer heterojunction array is completely released onto the target substrate, thereby completing the batch transfer of two-dimensional materials.