A method for fabricating wafer-level two-dimensional material arrays

Abstract

This invention provides a method for preparing wafer-level two-dimensional material arrays, specifically relating to the field of two-dimensional atomic crystal material transfer technology. The method includes: preparing a mixed solution according to a preset ratio; preparing a PDMS stamp with multiple PDMS protrusions on its upper surface, arranging the protrusions in a preset pattern; growing a continuous monolayer two-dimensional TMDs film on a growth substrate; bonding the PDMS protrusions of the PDMS stamp to the monolayer two-dimensional TMDs film; separating the monolayer two-dimensional TMDs film from the growth substrate using the mixed solution; peeling off the portion of the monolayer two-dimensional TMDs film outside the contact area with the upper surface of the PDMS protrusions to obtain a patterned monolayer two-dimensional TMDs film; and transferring the patterned monolayer two-dimensional TMDs film onto a target substrate. This method solves the problem of existing technologies being unable to transfer large-size monolayer two-dimensional TMDs films at low cost, high efficiency, and simple simplicity, thus failing to meet the requirements of large-scale grain integration.

Description

Technical Field

[0001] This invention relates to the field of two-dimensional atomic crystal material transfer technology, specifically to a method for preparing wafer-level two-dimensional material arrays. Background Technology

[0002] Two-dimensional transition metal chalcogenides (TMDs), represented by MoS2 and WSe2, exhibit unique advantages in constructing novel two-dimensional electronic devices due to their excellent structure and electrical properties, such as atomically thin single crystals, layered structure, absence of dangling bonds on the surface, interlayer van der Waals force bonding, suitable band gaps, and electron mobilities. Research has found that field-effect transistors (MoS2-FETs) based on two-dimensional TMDs materials, due to the absence of dangling bonds and van der Waals force bonding at the interface, show no significant change in carrier mobility when the channel thickness is gradually reduced to below 1 nm. MoS2-FETs also exhibit low leakage current (10⁻⁶) comparable to that of oxide semiconductors (IGZO-TFTs). -13 The advantages of (uA / um) have application potential in constructing two-dimensional pixel circuits (such as image sensors, photoelectric imaging, and display driving circuits).

[0003] Currently, a series of studies have been conducted on functional circuits based on two-dimensional devices. For example, MoS2-FETs and Micro-LED display chips have been monolithically integrated using the BEOL process to fabricate a 32×32 matrix of MoS2-FET pixel circuits, which has preliminarily verified the driving function of the micro-LED display matrix. From a display perspective: for a micro-LED display with a resolution of 320×240 pixels, 76,800 chips need to be integrated; for a micro-LED display with a resolution of 1080×720 pixels (720P), more than 770,000 chips need to be integrated. Therefore, to integrate a large number of chips onto a wafer, it is first necessary to transfer an array of two-dimensional TMDs material thin films onto the wafer, and then deposit source and drain motors on each array to obtain a field-effect transistor array. The field-effect transistor arrays are then interconnected to obtain a two-dimensional driving circuit.

[0004] Currently, mechanical exfoliation and chemical vapor deposition (CVD) are the main methods for obtaining two-dimensional materials. With in-depth research and improvements in growth processes, CVD has initially achieved the preparation of continuous thin films of wafer-scale two-dimensional materials (MoS2, h-BN, WSe2, etc.). These methods have solved to some extent the problems of small lateral dimensions and difficulty in controlling the number of layers in samples prepared by traditional mechanical exfoliation. However, in the process of constructing novel two-dimensional electronic devices, it is generally necessary to transfer the grown two-dimensional material to a new target substrate (such as SiO2 / Si substrate, flexible PET substrate, etc.) through a transfer step to achieve compatibility with silicon semiconductor processes or to realize the fabrication of flexible electronic devices.

[0005] The use of two-dimensional material transfer platforms for the targeted transfer of different two-dimensional materials is a common method for prototype device development and characterization in laboratories. Common transfer methods include dry transfer and wet transfer, with flexible organic polymers such as PMMA, PDMS, PS, and PVA typically used as transfer media. Based on the targeted transfer method, the transfer of two-dimensional materials from the micrometer (μm) to the centimeter (cm) scale has been achieved. However, to achieve high-density integration of two-dimensional electronic devices, the transferred two-dimensional materials often require subsequent microfabrication steps such as spin-coating photoresist, optical exposure, development, reactive ion etching (RIE), and resist removal to achieve patterning. These microfabrication steps are complex, costly, time-consuming, and prone to introducing impurity particles onto the material surface. Patent CN115763219A provides a method for preparing patterned monolayer two-dimensional materials. This method can achieve simple, efficient and low-cost transfer of patterned two-dimensional materials. However, this patent can obtain two-dimensional material arrays within a size range of 3mm*3mm (for example, MoS2 with a size of 20um can obtain several thousand MoS2 arrays). This technology cannot transfer large areas (such as MoS2 thin films with a diameter of 5cm). In existing commercial applications, large-area integrated grains are required, and two-dimensional material transfer technology needs to be applied to wafer-level substrates to achieve mass transfer of wafer-level two-dimensional material arrays.

[0006] In the process of realizing this invention, the applicant discovered that the prior art has at least the following problems: the existing low-cost, efficient and simple array transfer method of two-dimensional TMDs materials cannot meet the requirements of large-scale micro-LED chip integration. Therefore, it is necessary to develop a low-cost, repeatable and fast mass transfer method for transferring high-density two-dimensional materials on the wafer scale, so as to achieve large-scale chip integration on the wafer. Summary of the Invention

[0007] To address the problem of being unable to fabricate patterned single-layer two-dimensional materials at wafer-scale, embodiments of the present invention provide a method for fabricating wafer-level two-dimensional material arrays.

[0008] The method includes:

[0009] A mixed solution is prepared according to a preset ratio, wherein the mixed solution is composed of water and an alcohol-based organic solvent;

[0010] Prepare a PDMS stamp with multiple PDMS protrusions on its upper surface, and arrange the multiple PDMS protrusions in a predetermined pattern.

[0011] A continuous monolayer two-dimensional TMDs thin film is grown on a growth substrate;

[0012] The PDMS stamp is inverted so that the PDMS protrusions of the PDMS stamp are bonded to the single-layer two-dimensional TMDs film.

[0013] The PDMS stamp, the monolayer two-dimensional TMDs film, and the growth substrate, which are pasted together, are immersed in a mixed solution to separate the monolayer two-dimensional TMDs film from the growth substrate.

[0014] The single-layer two-dimensional TMDs film outside the contact portion with the upper surface of the PDMS protrusion is peeled off to obtain a patterned single-layer two-dimensional TMDs film.

[0015] The patterned monolayer two-dimensional TMDs thin film is transferred onto the target substrate.

[0016] The above technical solution has the following beneficial effects: By using patterned PDMS stamp technology, and using a mixed solution of water and ethanol, or a mixed solution of water and isopropanol as the transfer medium, a method for transferring patterned two-dimensional material thin films at the wafer size is achieved, which achieves the technical effects of simple operation, cost saving, repeatability, and rapid transfer. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic flowchart of a method for preparing a wafer-level two-dimensional material array according to an embodiment of the present invention;

[0019] Figure 2a This is a schematic diagram of the PDMS seal structure in an embodiment of the present invention;

[0020] Figure 2b This is an embodiment of the present invention. Figure 2a A magnified view of a portion of the image;

[0021] Figure 3a This is a schematic diagram of the growth substrate and the monolayer two-dimensional TMDs thin film in an embodiment of the present invention;

[0022] Figure 3b This is an embodiment of the present invention. Figure 3a A magnified view of a portion of the image;

[0023] Figure 4a This is a schematic diagram of an embodiment of the present invention in which the PDMS stamp is inverted so that the PDMS protrusions are tightly bonded to the two-dimensional TMDs film.

[0024] Figure 4b This is an embodiment of the present invention. Figure 4a A magnified view of a portion of the image;

[0025] Figure 5a This is a schematic diagram of a single-layer two-dimensional TMDs transferred to the upper surface of the PDMS protrusion in an embodiment of the present invention;

[0026] Figure 5b This is an embodiment of the present invention. Figure 5a A magnified view of a portion of the image;

[0027] Figure 6 This is a schematic diagram of transferring a patterned monolayer two-dimensional TMDs thin film to a target substrate in an embodiment of the present invention;

[0028] Figure 7 is a schematic diagram of the patterned monolayer two-dimensional TMDs thin film transferred to the target substrate in an embodiment of the present invention;

[0029] Figure 8 These are optical images of a single-layer two-dimensional TMDs thin film grown on a growth substrate using a CVD process, as described in an embodiment of the present invention.

[0030] Figure 9 This is an optical image showing the tight bonding between the PDMS protrusions and the single-layer two-dimensional TMDs film in an embodiment of the present invention;

[0031] Figure 10 This is an optical image of a patterned single-layer two-dimensional TMDs film transferred onto a PDMS stamp in an embodiment of the present invention.

[0032] Figure 11 This is an optical image of the patterned single-layer two-dimensional TMDs thin film 06 transferred to the target substrate in an embodiment of the present invention;

[0033] Figure 12a An image of a patterned PDMS stamp magnified 50 times under an optical microscope in an embodiment of the present invention;

[0034] Figure 12b This is an image of a patterned PDMS stamp magnified 100 times under an optical microscope, according to an embodiment of the present invention.

[0035] Figure 12c This is an image of a patterned PDMS stamp magnified 200 times under an optical microscope, according to an embodiment of the present invention.

[0036] Figure 12d This is a 500x magnified image of a patterned PDMS stamp under an optical microscope, as shown in an embodiment of the present invention.

[0037] Figure 13a This is a 50x magnified image of the first patterned monolayer two-dimensional TMDs film transferred onto the target substrate in an embodiment of the present invention;

[0038] Figure 13b This is a 100x magnified image of the first patterned monolayer two-dimensional TMDs film transferred to the target substrate in an embodiment of the present invention under an optical microscope;

[0039] Figure 13c This is a 200x magnified image of the first patterned monolayer two-dimensional TMDs film transferred to the target substrate in an embodiment of the present invention under an optical microscope;

[0040] Figure 13d This is a 500x magnified image of the first patterned monolayer two-dimensional TMDs film transferred onto the target substrate in an embodiment of the present invention;

[0041] Figure 14a An image magnified 100x under an optical microscope of the second patterned monolayer two-dimensional TMDs film transferred onto the target substrate in an embodiment of the present invention;

[0042] Figure 14b An image magnified 200x under an optical microscope of the second patterned monolayer two-dimensional TMDs film transferred onto the target substrate in an embodiment of the present invention;

[0043] Figure 15a This refers to the contact angle of the droplet on the target substrate surface when water is selected as the transfer medium in this embodiment of the invention.

[0044] Figure 15b This refers to the contact angle of the droplet on the target substrate surface when a water / ethanol mixed solution is used as the transfer medium in the embodiments of the present invention.

[0045] Figure 16a This refers to the contact angle of the droplet on the PDMS stamp surface when water is selected as the transfer medium in this embodiment of the invention.

[0046] Figure 16bThis refers to the contact angle of the droplets on the PDMS stamp surface when a water / ethanol mixture is used as the transfer medium in this embodiment of the invention.

[0047] Figure 17a This is a 200x magnified image of a two-dimensional material transistor fabricated based on a transferred patterned monolayer two-dimensional TMDs thin film 06 in an embodiment of the present invention, under an optical microscope.

[0048] Figure 17b This is a 1000x magnified image of a two-dimensional material transistor fabricated based on a transferred patterned monolayer two-dimensional TMDs thin film 06 in an embodiment of the present invention under an optical microscope;

[0049] Figure 17c This is an output characteristic curve of a two-dimensional material transistor in an embodiment of the present invention, wherein the inset is a schematic diagram of the corresponding circuit connection;

[0050] Figure 17d This is another typical transfer characteristic curve of a two-dimensional material transistor in the embodiments of the present invention;

[0051] Figure 18a These are the output characteristic curves obtained by testing 1000 two-dimensional material transistors in this embodiment of the invention;

[0052] Figure 18b This is a current distribution diagram obtained from testing 1000 two-dimensional material transistors in an embodiment of the present invention.

[0053] The reference numerals in the attached figures are as follows:

[0054] 01. PDMS stamp; 02. PDMS protrusion; 03. Monolayer two-dimensional TMDs film; 04. Growth substrate; 05. Target substrate; 06. Patterned monolayer two-dimensional TMDs film. Detailed Implementation

[0055] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0056] The technical solutions of the present invention will be described in detail below with reference to specific application examples. For technical details not described in the implementation process, please refer to the relevant descriptions above.

[0057] like Figure 1As shown, to achieve low-cost, repeatable, and rapid transfer of patterned two-dimensional materials at the wafer size, this invention proposes a method for fabricating wafer-level two-dimensional material arrays. This method eliminates the need for microfabrication processes such as exposure-etching, and simultaneously achieves two-dimensional material patterning while transferring wafer-sized two-dimensional materials. Specifically, it includes:

[0058] S1. Prepare a mixed solution according to a preset ratio, wherein the mixed solution is composed of water and an alcohol-based organic solvent;

[0059] S2. Prepare a PDMS stamp 01 with multiple PDMS protrusions 02 on its upper surface, and arrange the multiple PDMS protrusions 02 in a preset pattern.

[0060] S3. A continuous monolayer two-dimensional TMDs thin film 03 is grown on the growth substrate 04;

[0061] S4. Invert the PDMS stamp 01 so that the PDMS protrusion 02 of the PDMS stamp 01 is bonded to the single-layer two-dimensional TMDs film 03.

[0062] S5. Immerse the PDMS stamp 01, the single-layer two-dimensional TMDs film 03, and the growth substrate 04, which are pasted together, in a mixed solution to separate the single-layer two-dimensional TMDs film 03 from the growth substrate 04.

[0063] S6. Peel off the single-layer two-dimensional TMDs film 03 outside the contact portion with the upper surface of the PDMS protrusion 02 to obtain a patterned single-layer two-dimensional TMDs film 06.

[0064] S7. Transfer the patterned single-layer two-dimensional TMDs thin film 06 onto the target substrate 05.

[0065] In 2019, IMEC successfully introduced 2D FETs on a 300mm silicon process line, demonstrating its compatibility with silicon processes and providing a possible pathway for the development of post-Moore devices. Furthermore, thanks to continuous optimization of low-contact-resistance metal and dielectric insulating layer fabrication processes, field-effect transistors based on two-dimensional TMDs materials (such as MoS2-FETs) have exhibited on-state current values ​​(IL) comparable to those of low-temperature polycrystalline silicon (LTPS-TFTs). ON =~1.27mA / um) and high mobility (122.6cm) 2 V -1 s -1 The characteristics of MoS2-FETs are as follows. Meanwhile, MoS2-FETs exhibit low leakage current (10⁻⁶ Ω·cm) comparable to that of IGZO-TFTs. -13The advantages of (µA / µm) in two-dimensional (TMD) pixel circuits (such as image sensors, photoelectric imaging, and display driving circuits) have application potential. Currently, a series of studies have been conducted on functional circuits based on two-dimensional devices. For example, a 32×32 matrix of MoS2-FET pixel circuits was fabricated by monolithically integrating MoS2-FETs with Micro-LED display chips using the BEOL process, initially verifying the driving function of the micro-LED display matrix. From a display perspective: for a 320×240 pixel resolution micro-LED display, 76,800 chips need to be integrated; for a 720P pixel resolution micro-LED display (1080×720), more than 770,000 chips need to be integrated. Therefore, to adapt to large-scale integration, it is necessary to fabricate wafer-sized two-dimensional TMDs materials and pattern them.

[0066] Wafers refer to the size of silicon wafers, such as 2 inches, 4 inches, 8 inches, and 12 inches. A 2-inch wafer has a diameter of 5 cm. MoS2 has a size of 20 μm, which can yield several thousand MoS2 arrays. However, this technology cannot transfer large areas (e.g., MoS2 films with a diameter of 5 cm). This invention, through the preparation of a suitable mixed solution as a transfer medium, enables the single transfer of MoS2 films with a diameter of 5 cm (2 inches). Therefore, more than one million MoS2 arrays can be obtained on a 2-inch wafer. In this invention, the mixed solution is composed of water and ethanol, or water and isopropanol. Compared to pure water, this mixed solution has lower polarity and better wetting properties. By adjusting the mixing ratio, the polarity of the mixed solution (i.e., the contact angle between the droplet and the growth substrate 04, and between the droplet and the PDMS stamp 01) is controlled, allowing the single-layer two-dimensional TMDs film 03 to separate from the growth substrate 04 more quickly.

[0067] The following is a detailed explanation of the steps involved in fabricating a 2-inch patterned monolayer two-dimensional TMDs thin film 06:

[0068] Prepare 500 ml of a mixed solution consisting of water and ethanol.

[0069] like Figure 2a , Figure 2b As shown, a 4-inch PDMS stamp 01 is first prepared, containing periodically and regularly arranged PDMS protrusions 02. The upper surface of the PDMS protrusions 02 is flat, smooth, and has a certain degree of adhesion. Figure 12a , Figure 12b , Figure 12c , Figure 12dImages of patterned PDMS stamps 01 under optical microscopes at different magnifications, i.e., images of PDMS stamps 01 containing periodically and regularly arranged PDMS protrusions 02, wherein the dimensions (length × width × height) of the PDMS protrusions 02 are 20 × 20 × 20 μm, and the spacing between the protrusions is 20 μm.

[0070] like Figure 3a , Figure 3b As shown, a uniform and continuous monolayer two-dimensional TMDs thin film 03 was grown on a 2-inch growth substrate 04 using CVD technology. Figure 8 The image shown is an optical image of a uniform, continuous monolayer two-dimensional TMDs thin film 03 grown on a growth substrate 04.

[0071] like Figure 4a , 4b As shown, the PDMS stamp 01 is inverted, causing the PDMS protrusions 02 to contact the monolayer two-dimensional TMDs film 03. Under external pressure, the upper surface of the PDMS stamp 01 adheres tightly to the surface of the monolayer two-dimensional TMDs film 03. At this point, the PDMS stamp 01 and the monolayer two-dimensional TMDs film 03 are divided into two distinct regions: a contact region, where the PDMS protrusions are tightly adhered to the monolayer two-dimensional TMDs film 03; and a non-contact region, the area formed between the PDMS protrusions, which is equivalent to a capillary with a micrometer-scale size. Figure 9 The image shown is an optical image of PDMS protrusions tightly bonded to a single-layer two-dimensional TMDs film.

[0072] Pour the mixture into a wide-mouthed container (greater than 4 inches in diameter); such as Figure 4a , 4b The PDMS stamp 01 and the growth substrate 04 containing a single-layer two-dimensional TMDs film 03 are immersed together in a mixed solution, wherein the PDMS stamp 01, the single-layer two-dimensional TMDs film 03 and the growth substrate 04 are closely bonded together.

[0073] Due to the lower polarity of the mixed solution, it easily penetrates into the center of the monolayer two-dimensional TMDs film 03 along the non-contact region, driven by capillary force. Under the action of the mixed solution, the monolayer two-dimensional TMDs film 03 rapidly separates from its growth substrate 04.

[0074] Under the action of the mixed solution, the single-layer two-dimensional TMDs film 03 in the non-contact area ruptures under the action of liquid tension, while the single-layer two-dimensional TMDs film 03 in the contact area remains intact under the action of the self-adhesive force of the PDMS protrusion 02.

[0075] like Figure 5a , Figure 5b , Figure 10As shown, under the self-adhesive force of the PDMS protrusions 02, the single-layer two-dimensional TMDs film 03 is transformed into a patterned single-layer two-dimensional TMDs film 06 with periodic and regular arrangement of protrusions consistent with the size of the protrusions on the upper surface of the PDMS stamp 01.

[0076] like Figure 6 , Figure 7a , Figure 7b , Figure 11 The patterned monolayer two-dimensional TMDs thin film 06 is transferred onto the target substrate 05 to obtain a 2-inch patterned monolayer two-dimensional material, i.e., a wafer-level two-dimensional material array. High-quality transfer of more than 1 million crystal arrays can be achieved in a single transfer. Figure 13a , Figure 13b , Figure 13c , Figure 13d Images of the first patterned monolayer two-dimensional TMDs film 06 under optical microscopes at different magnifications, i.e., images of the patterned monolayer two-dimensional TMDs film 06 containing a periodic, regular arrangement of protrusions consistent with the size of the protrusions on the upper surface of the PDMS stamp 01.

[0077] Furthermore, the alcoholic organic solvent is ethanol or isopropanol. Ethanol and isopropanol are commonly used alcoholic organic solvents, readily available, and inexpensive.

[0078] Furthermore, the ratio of water to alcoholic organic solvent in the mixed solution ranges from 2:1 to 1:2. Within this mixing ratio range, the polarity of the mixed solution serves as a good transfer medium for separating the monolayer two-dimensional TMDs film 03 from the growth substrate 04. Too much water in the mixed solution will affect the transfer rate, while too little water can easily damage the material.

[0079] Furthermore, the ratio of water to water and water-to-alcohol organic solvent in the mixed solution ranges from 1.5:1 to 1:1.5. By further narrowing the mixing ratio range of the mixed solution, the polarity of the mixed solution within this range results in a more favorable transfer rate.

[0080] Furthermore, the ratio of water to alcohol-based organic solvent in the mixed solution is 1:1. A 1:1 mixing ratio is preferred in the mixed solution to facilitate its preparation and to facilitate rapid separation of the monolayer two-dimensional TMDs film 03 and the growth substrate 04.

[0081] like Figure 15a The image shows that when water is used as the transfer medium, the contact angle of a water droplet on the surface of the target substrate 05 is 50.04°. Figure 15bThe figure shows that when a mixed solution of water and ethanol is used as the transfer medium, the contact angle of the droplets on the target substrate 05 is 12.88°. The smaller the contact angle, the easier it is for the droplets to spread on the surface of the target substrate 05.

[0082] Specifically, Figure 16a The figure shows that when water is used as the transfer medium, the contact angle of the water droplet on the surface of the PDMS stamp 01 is 123.95°. Figure 16b The figure shows that when a mixed solution of water and ethanol is used as the transfer medium, the contact angle of the droplet on the PDMS stamp 01 surface is 91.41°. The larger the contact angle, the more hydrophobic the PDMS stamp 01 is, and the easier it is for the droplet to aggregate into a small ball on the PDMS stamp 01 surface.

[0083] The non-contact region can be simplified to a capillary at the micrometer scale. Contact behavior within the capillary region can be as follows: Figure 15a , Figure 15b , Figure 16a and Figure 16b As shown, a curved liquid surface is formed, and the pressure inside the liquid (Pin) and the pressure outside the liquid (Pout) will be different. ΔP represents the Laplace pressure (Pin-Pout) in the capillary tube, which is related to the contact angle of pure water. The Laplace equation can be rewritten as: h is the capillary height, γ1 is the surface tension of the liquid, and θ1 and θ2 are the contact angles of the droplet on the target substrate 05 and the PDMS stamp 01, respectively.

[0084] The Laplace pressure within the capillary was calculated using different solutions. Under pure water conditions, the contact angles of the water droplet on the SiO2 / Si substrate and the patterned PDMS surface were 50.04° and 123.95°, respectively. Therefore, the calculated... The estimated γ1 value of pure water is approximately 72.20 × 10⁻⁶. -3 N / m, h is 20m, so ΔP1 is calculated to be approximately 0.3 kPa.

[0085] For a 2:1 mixture of water and ethanol, the contact angles of a single drop of the mixture on the target substrate 05 and the PDMS stamp 01 surface are 43.04° and 108.91°, respectively. Therefore, the calculated... The estimated value of γ1 for a 2:1 mixture of water and ethanol is approximately 33.58 × 10⁻⁶. -3 N / m, h is 20m, so ΔP2 is calculated to be approximately 0.68 kPa.

[0086] For a 1:1 mixture of water and ethanol, the contact angles of a single drop of the mixture on the target substrate 05 and the PDMS stamp 01 surface are 91.41° and 12.88°, respectively. The calculated... The estimated value of γ1 for a 1:1 mixture of water and ethanol is approximately 28.51 × 10⁻⁶. -3 N / m, h is 20m, so ΔP3 is calculated to be approximately 1.35 kPa.

[0087] The value of ΔP3 is 4.50 times larger than ΔP1, indicating that the mixed solution of water and ethanol is more permeable. Therefore, low-polarity solutions are essential for rapid two-dimensional array transfer.

[0088] Further, a patterned PDMS stamp with multiple PDMS protrusions on its upper surface is prepared, and the multiple PDMS protrusions are arranged in a preset pattern, including:

[0089] Design patterned molds;

[0090] The patterned mold is filled with PDMS using a spin coating process;

[0091] The PDMS within the patterned mold is cured.

[0092] The cured PDMS is demolded from the patterned mold to obtain a patterned PDMS stamp.

[0093] PDMS stamp 01 is obtained through a patterned mold, such as the SU-8 patterned mold. The mold is designed to meet specific requirements (e.g., pattern shape, arrangement, size). PDMS is spin-coated into the patterned mold. Under centrifugal force, the mold is filled with PDMS, resulting in a smooth and even surface. Since PDMS is a viscous liquid, it needs to be cured after filling the mold. After curing, the PDMS is demolded from the patterned mold, ultimately yielding the patterned PDMS stamp 01. Figure 2a , Figure 2b , Figure 12a , Figure 12b , Figure 12c , Figure 12d As shown, the PDMS raised bumps 02 on the PDMS stamp 01 have preset pattern styles and arrangements. The upper surface of the PDMS raised bumps 02 is flat, smooth, and has a certain degree of adhesion.

[0094] The process used to grow the continuous monolayer two-dimensional TMDs thin film on the growth substrate includes CVD, MOCVD metal-organic chemical vapor deposition, and PECVD plasma-enhanced chemical vapor deposition. The two-dimensional TMDs thin film includes MoS2 or WSe2 or WS2 or MoSe2 or MoTe2.

[0095] In the embodiments of the present invention, CVD chemical vapor deposition, MOCVD metal-organic chemical vapor deposition, and PECVD plasma-enhanced chemical vapor deposition can all generate monolayer two-dimensional TMDs thin films 03. The selected TMDs thin film can be a monolayer, continuous molybdenum disulfide (MoS2) film, or tungsten diselenide (WSe2) film, or tungsten disulfide (WS2), or molybdenum diselenide (MoSe2), or molybdenum distelluride (MoTe2). The monolayer, continuous TMDs thin film is uniformly distributed on the growth substrate 04.

[0096] Further, the transfer of the patterned monolayer two-dimensional TMDs thin film 06 onto the target substrate 05 includes:

[0097] The PDMS protrusion 02 on which the patterned single-layer two-dimensional TMDs film 06 is attached is brought into contact with the target substrate 05, so that the patterned single-layer two-dimensional TMDs film 06 is attached to the target substrate 05.

[0098] The PDMS stamp 01 is separated from the patterned monolayer two-dimensional TMDs film 06 so that the patterned monolayer two-dimensional TMDs film 06 is transferred onto the target substrate 05.

[0099] like Figure 6 As shown, it will be as follows Figure 5a , Figure 5b The PDMS stamp 01, on which the patterned monolayer two-dimensional TMDs film 06 is attached, is inverted. The inverted PDMS stamp 01 contacts the target substrate 05. An external force is then applied to the PDMS stamp 01, causing the patterned monolayer two-dimensional TMDs film 06 on the upper surface of the PDMS protrusion 02 to adhere to the target substrate 05. The PDMS stamp 01 is then slowly lifted, separating the patterned monolayer two-dimensional TMDs film 06 from the PDMS protrusion 02.

[0100] Further, the step of separating the PDMS stamp from the patterned monolayer two-dimensional TMDs film 06 to transfer the patterned monolayer two-dimensional TMDs film 06 onto the target substrate 05 includes:

[0101] The target substrate 05 is heated to a preset temperature;

[0102] Lift the PDMS stamp 01, and the PDMS stamp 01 separates from the patterned single-layer two-dimensional TMDs film 06.

[0103] The patterned single-layer two-dimensional TMDs thin film 06 is transferred onto the target substrate 05.

[0104] To reduce the stickiness of the PDMS stamp 01, the target substrate 05, which is bonded together with the PDMS stamp 01 and the patterned monolayer two-dimensional TMDs film 06, is placed on a heating stage. The heating stage is heated rapidly to 80°C-100°C, preferably to 100°C, within three minutes, so that the stickiness of the PDMS is reduced to 0. After heating to the preset temperature, the PDMS stamp 01 is lifted, so that the patterned monolayer two-dimensional TMDs film 06 on the original surface of the PDMS protrusion 02 is separated from the PDMS protrusion 02.

[0105] Further, the target substrate 05 comprises: a silicon substrate containing a silicon dioxide layer, a glass substrate, and a flexible polyimide or flexible polyethylene terephthalate substrate.

[0106] like Figure 6 The target substrate 05 shown is a silicon substrate with a silicon dioxide layer of size 1cm × 1cm, wherein the thickness of the silicon dioxide layer is approximately 300nm. Alternatively, a glass substrate, flexible polyimide, or flexible polyethylene terephthalate can be used as the substrate.

[0107] Furthermore, the area of ​​the growth substrate 04 is not less than the area of ​​the PDMS stamp 01; the area of ​​the target substrate 05 is not less than the area of ​​the PDMS stamp 01.

[0108] Since the PDMS protrusions 02 on the PDMS stamp 01 are the carriers for preparing and transferring the patterned monolayer two-dimensional TMDs film 06, if the area of ​​the growth substrate 04 is smaller than the PDMS stamp 01, the protrusions in the PDMS stamp 01 cannot be completely covered by the monolayer two-dimensional TMDs film 03, and the patterned monolayer two-dimensional TMDs film 06 with the preset arrangement cannot be obtained. When generating the continuous monolayer two-dimensional TMDs film 03, the adhesiveness of the upper surface of the PDMS protrusions 02 in the PDMS stamp 01 is used to stick the film to the upper surface of the PDMS protrusions 02, and then the film is transferred to the target substrate 05 through the PDMS stamp 01. If the area of ​​the target substrate 05 is smaller than the PDMS stamp 01, only some of the PDMS protrusions 02 can contact the target substrate 05, so only part of the patterned monolayer two-dimensional TMDs film 06 can be transferred, and the patterned two-dimensional material with the preset arrangement cannot be obtained on the target substrate 05.

[0109] like Figure 14a , 14bThe image shown is an optical microscope image of a patterned single-layer two-dimensional TMDs thin film with a pattern of two-dimensional material micron strips, obtained by changing the pattern of the PDMS image (i.e., replacing regular PDMS protrusions with regular PDMS micron strips) using the same transfer process. The corresponding two-dimensional material micron strips have a width of 20 μm and a spacing of 20 μm. This demonstrates that the method provided by this invention can achieve reproducibility of the transfer process.

[0110] After generating a patterned two-dimensional material using the method of this application, the patterned two-dimensional material is used to fabricate a two-dimensional material transistor, such as... Figure 17a , Figure 17b The diagram illustrates the fabrication of a two-dimensional material transistor based on a patterned monolayer two-dimensional TMDs thin film after transfer. The specific fabrication process, using MoS2 as an example, mainly includes spin-coating a layer of photoresist onto the MoS2 array surface; baking the photoresist at 150 degrees Celsius for 110 seconds; exposing the desired electrode pattern using a laser direct-write device; developing the image using a developer; depositing Cr / Au (5nm / 30nm) electrodes as the source (S) and drain (D) of the MoS2 channel using an electron beam evaporation device; and performing a lift-off using a resist remover to obtain a patterned MoS2-FET, i.e., a MoS2-FET array.

[0111] like Figure 17c , Figure 17d The figures shown are the output characteristic curves and transfer characteristic curves of a two-dimensional material transistor, respectively. Figure 17c The illustrations in the figure show the corresponding circuit connection diagrams; the output characteristic curves of the MoS2-FET were tested using a semiconductor analyzer (B1500A).

[0112] like Figure 18a As shown, two-dimensional material transistors fabricated from patterned two-dimensional materials prepared using the method provided by this invention were tested. For example, 1000 MoS2 transistors (20×50 MoS2 array) were tested, and 979 output characteristic curves were obtained. Figure 18b The embodiment of the present invention shown tests the current (I) of a two-dimensional material transistor. D The distribution diagram of the current (I) was obtained by testing 1000 MoS2 transistors (20×50 MoS2 array). D The distribution diagram shows that the two-dimensional material transistors produced using the method provided by this invention have good consistency.

[0113] This invention enables low-cost, repeatable, and rapid transfer of wafer-level two-dimensional arrays. The method eliminates the need for microfabrication processes such as exposure and etching, and simultaneously patterns the wafer-sized two-dimensional material TMDs thin film 03. By controlling the polarity of the transfer medium, the two-dimensional material TMDs thin film 03 is rapidly separated from the growth substrate 04, which significantly improves the fabrication efficiency of two-dimensional materials and reduces fabrication costs. Based on this method, a single transfer can achieve the rapid transfer of more than one million two-dimensional arrays on a 2-inch wafer, contributing to the commercialization of two-dimensional integrated circuits.

[0114] It should be understood that the specific order or hierarchy of steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process may be rearranged without departing from the scope of this disclosure. The appended method claims provide elements of various steps in an exemplary order and are not intended to limit the scope to the specific order or hierarchy described.

[0115] In the above detailed description, various features are combined together in a single embodiment to simplify this disclosure. This approach to disclosure should not be construed as reflecting an intention that embodiments of the claimed subject matter require more features than are explicitly stated in each claim. Rather, as reflected in the appended claims, the invention is presented with fewer features than all of the features of the single disclosed embodiment. Therefore, the appended claims are hereby explicitly incorporated into the detailed description, wherein each claim stands alone as a preferred embodiment of the invention.

[0116] The disclosed embodiments have been described above to enable any person skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments without departing from the spirit and scope of this disclosure. Therefore, this disclosure is not limited to the embodiments given herein, but is consistent with the broadest scope of the principles and novel features disclosed in this application.

[0117] The foregoing description includes examples of one or more embodiments. It is certainly impossible to describe all possible combinations of components or methods in order to describe the above embodiments, but those skilled in the art will recognize that further combinations and arrangements of the various embodiments are possible. Therefore, the embodiments described herein are intended to cover all such changes, modifications, and variations that fall within the scope of the appended claims. Furthermore, the term "comprising" as used in the specification or claims is interpreted in a manner similar to the term "including," as interpreted when used as a conjunction in the claims. Additionally, the use of any term "or" in the specification of the claims is intended to mean "non-exclusive or."

[0118] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for fabricating wafer-level two-dimensional material arrays, characterized in that, The method includes: A mixed solution is prepared according to a preset ratio, wherein the mixed solution is composed of water and an alcohol-based organic solvent; Prepare a PDMS stamp (01) with multiple PDMS protrusions (02) on its upper surface, and arrange the multiple PDMS protrusions (02) in a predetermined pattern. A continuous monolayer two-dimensional TMDs thin film (03) is grown on a growth substrate (04); The PDMS stamp (01) is inverted so that the PDMS protrusion (02) of the PDMS stamp (01) is bonded to the single-layer two-dimensional TMDs film (03); The PDMS stamp (01), the monolayer two-dimensional TMDs film (03), and the growth substrate (04) that are pasted together are immersed in a mixed solution to separate the monolayer two-dimensional TMDs film (03) from the growth substrate (04). Peel off the single-layer two-dimensional TMDs film (03) outside the contact portion with the upper surface of the PDMS protrusion (02) to obtain a patterned single-layer two-dimensional TMDs film (06); The patterned single-layer two-dimensional TMDs thin film (06) is transferred onto the target substrate (05) to obtain a wafer-level two-dimensional material array.

2. The method for fabricating wafer-level two-dimensional material arrays as described in claim 1, characterized in that, The alcohol-based organic solvent is ethanol or isopropanol.

3. The method for fabricating wafer-level two-dimensional material arrays as described in claim 1, characterized in that, The ratio of water to alcoholic organic solvent in the mixed solution is in the range of 2:1 to 1:

2.

4. The method for fabricating wafer-level two-dimensional material arrays as described in claim 1, characterized in that, The ratio of water to alcoholic organic solvent in the mixed solution is in the range of 1.5:1 to 1:1.

5.

5. The method for fabricating wafer-level two-dimensional material arrays as described in claim 1, characterized in that, The ratio of water to alcoholic organic solvent in the mixed solution is 1:

1.

6. The method for fabricating wafer-level two-dimensional material arrays as described in claim 1, characterized in that, The process of preparing a patterned PDMS stamp (01) with multiple PDMS protrusions (02) on its upper surface, and arranging the multiple PDMS protrusions (02) in a preset pattern, includes: Design patterned molds; The patterned mold is filled with PDMS using a spin coating process; The PDMS within the patterned mold is cured. The cured PDMS is demolded from the patterned mold to obtain a patterned PDMS stamp (01).

7. The method for fabricating wafer-level two-dimensional material arrays as described in claim 1, characterized in that, The process of transferring the patterned monolayer two-dimensional TMDs thin film (06) onto the target substrate (05) includes: The PDMS protrusion (02) on which the patterned monolayer two-dimensional TMDs film 06 is attached is brought into contact with the target substrate (05) so that the patterned monolayer two-dimensional TMDs film (06) is attached to the target substrate (05); Separate the PDMS stamp (01) from the patterned monolayer two-dimensional TMDs film (06) so that the patterned monolayer two-dimensional TMDs film (06) can be transferred onto the target substrate (05).

8. The method for fabricating wafer-level two-dimensional material arrays as described in claim 7, characterized in that, The step of separating the PDMS stamp (01) from the patterned monolayer two-dimensional TMDs film (06) to transfer the patterned monolayer two-dimensional TMDs film (06) onto the target substrate (05) includes: The target substrate (05) is heated to a preset temperature; The PDMS stamp (01) is lifted up, and the PDMS stamp (01) is separated from the patterned single-layer two-dimensional TMDs film (06); The patterned monolayer two-dimensional TMDs thin film (06) is transferred onto the target substrate (05).

9. The method for fabricating wafer-level two-dimensional material arrays as described in claim 1, characterized in that, The target substrate (05) comprises: a silicon substrate containing a silicon dioxide layer, a glass substrate, and a flexible polyimide or flexible polyethylene terephthalate substrate.

10. The method for fabricating wafer-level two-dimensional material arrays as described in claim 1, characterized in that, The area of ​​the growth substrate (04) is not less than the area of ​​the PDMS stamp (01); the area of ​​the target substrate (05) is not less than the area of ​​the PDMS stamp (01).

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