Water-based liquid-solid phase change cleaning method
By utilizing the liquid-solid phase change of water and the adhesive force of ice to remove contaminants from the surface of two-dimensional materials, this method solves the problem that traditional methods may damage material properties and achieves a non-destructive and highly efficient cleaning effect.
Patent Information
- Application Number
- CN202410544503.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-30
- Publication Date
- 2025-10-31
AI Technical Summary
Existing technologies are ineffective at removing contaminants, such as polymers and inorganic particles, from the surface of two-dimensional materials, and commonly used methods may impair material properties or introduce defects.
A water-based liquid-solid phase change method is used to remove contaminants by leveraging the adhesive force of ice. The method includes the following steps: water is dropped onto the target surface to form a water film, the surface is cooled to below the freezing point to freeze into an ice layer, the ice layer is peeled off to remove the contaminants, and finally the residual water is heated to evaporate.
It achieves non-destructive removal of contaminants from two-dimensional material surfaces, applicable to a variety of surfaces, including two-dimensional materials and substrates, avoiding the defects and damage of traditional methods, and providing efficient and wide-ranging cleaning effects.
Smart Images
Figure CN120861510A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of nanomaterials technology, and more specifically to a water-based liquid-solid phase transition cleaning method. Background Technology
[0002] Two-dimensional materials are currently at the forefront of cutting-edge science and technology. Chemical vapor deposition (CVD) is the most promising strategy for preparing high-yield and high-quality two-dimensional materials. However, two-dimensional materials prepared using CVD methods still need to be transferred to other substrates for further characterization and application. In traditional transfer processes, residual contaminants such as polymers are easily induced during transfer and are difficult to remove. At the same time, other impurities such as dust and organic molecules commonly found on two-dimensional materials can also contaminate the surface of the materials and impair their properties.
[0003] The most common methods for developing effective cleaning methods for two-dimensional materials are high-temperature annealing or plasma treatment. However, the extreme conditions involved in these methods can lead to defects in the two-dimensional materials, and the removable contaminants are limited to carbohydrates or organic molecules. Mechanical cleaning methods such as AFM scanning can remove a variety of impurities, including polymers and inorganic particles, but they also suffer from low efficiency and limited range.
[0004] Therefore, there is still a lack of a universal, wide-ranging, and non-destructive cleaning method for two-dimensional materials and substrates. Summary of the Invention
[0005] To address the aforementioned technical problems, the present invention aims to provide a water-based liquid-solid phase change cleaning method. This method utilizes the adhesive properties of ice to clean contaminants from a target surface.
[0006] To achieve the above objectives, the present invention provides a water-based liquid-solid phase change cleaning method, wherein the method includes the following steps:
[0007] (1) Place water droplets on the target surface, and then cover the water droplets on the target surface with an auxiliary substrate to compress the water droplets into a water film;
[0008] (2) Lower the temperature to a clean temperature below the freezing point, so that the water film freezes into an ice layer;
[0009] (3) Peel off the auxiliary substrate along with the ice layer so that the pollutants are removed with the ice layer;
[0010] (4) Heat and evaporate the water remaining on the target surface to complete the cleaning of contaminants on the target surface;
[0011] The cleaning temperature is 0°C to -30°C.
[0012] According to a specific embodiment of the present invention, preferably, the affinity of the ice layer to the target surface is lower than the affinity of the ice layer to the contaminant; the affinity of the ice layer to the target surface is lower than the affinity of the ice layer to the auxiliary substrate; and the affinity of the contaminant to the target surface is lower than the affinity of the contaminant to the ice layer.
[0013] According to a specific embodiment of the present invention, preferably, the target surface comprises a two-dimensional material and / or a substrate.
[0014] According to a specific embodiment of the present invention, preferably, the two-dimensional material includes one or more of graphene, hBN (hexagonal boron nitride), MXene (graphene-like material), two-dimensional transition metal dichalcogenides (TMDs), layered transition metal oxides, layered double hydroxides, etc.
[0015] According to a specific embodiment of the present invention, preferably, the substrate material includes one or more combinations of SiO2 / Si wafers, Si wafers, sapphire, mica, polymers, etc. More preferably, the polymer material includes epoxy resin substrates and / or plexiglass substrates, etc.
[0016] In some specific embodiments, preferably, the two-dimensional transition metal dichalcogenide includes one or more combinations of MoS2, ReS2, WS2, MoSe2, ReSe2, etc.
[0017] In some specific embodiments, preferably, the layered transition metal oxide is Bi2O2Se.
[0018] In some specific embodiments, preferably, the layered double hydroxide is hydrotalcite.
[0019] The inventors of this invention discovered that different cleaning temperatures are suitable for different surfaces. The key is to adjust the cleaning temperature to ensure a strong adhesion between contaminants and ice without damaging the two-dimensional material or substrate, thus achieving contaminant-only removal. The inventors further tested the change in the adhesion force of ice to glass at different temperatures. Shear strength and tensile strength are two indicators of the bonding strength between ice and the substrate. Figure 1 As can be seen, both increase with decreasing temperature, indicating that the bonding force between ice and the substrate increases with decreasing temperature. This invention primarily concerns tensile strength.
[0020] According to a specific embodiment of the present invention, preferably, when the target surface is a substrate, the cleaning temperature is -5°C to -30°C.
[0021] According to a specific embodiment of the present invention, preferably, when the target surface is a two-dimensional material, the cleaning temperature is -20°C to 0°C.
[0022] The inventors of this invention discovered that two-dimensional materials can be divided into those with strong interaction with the substrate and those with weak interaction, allowing for adjustment of the cleaning temperature based on specific circumstances. The degree of interaction is measured by whether the two-dimensional material adheres to the ice during cleaning, leading to separation from the substrate. Therefore, the applicable cleaning temperature varies depending on the two-dimensional material and the substrate, primarily depending on the bonding strength between the two-dimensional material and the substrate. Figure 2 The results of the effects of ice on two-dimensional material TMDs at different temperatures show that for two-dimensional materials with weak interaction with the substrate, temperatures from -10℃ to 0℃ can be used so that the ice can only adhere to contaminants attached to the substrate and the surface of the two-dimensional material, avoiding damage to the two-dimensional material during the cleaning process. For two-dimensional materials with strong interaction with the substrate, such as graphene, temperatures below -10℃ can be used to achieve better cleaning results.
[0023] According to a specific embodiment of the present invention, preferably, when the target surface is a two-dimensional transition metal dichalcogenide, the cleaning temperature is 0°C to -15°C.
[0024] According to a specific embodiment of the present invention, preferably, when the target surface is graphene, the cleaning temperature is -10°C to -20°C.
[0025] According to a specific embodiment of the present invention, preferably, when the target surface is a layered transition metal oxide, the cleaning temperature is -10°C to -20°C.
[0026] According to a specific embodiment of the present invention, preferably, the auxiliary substrate is made of one or more of the following materials: glass, quartz, and metal. The auxiliary substrate needs to have strong adhesion to the ice layer, enabling it to peel the ice layer off the target surface.
[0027] In some specific embodiments, preferably, the metal includes one or more of the following: copper substrate, gold substrate, platinum substrate, etc.
[0028] According to a specific embodiment of the present invention, preferably, the contaminant includes one or more of polymers, inorganic particles, and dust. More preferably, the polymer in the contaminant includes PMMA, etc. Since the contaminant is generally an irregular three-dimensional structure, it has a larger contact area with ice compared to two-dimensional materials, and is also easier to be adhered and peeled off by ice through mechanical force.
[0029] According to a specific embodiment of the present invention, preferably, the temperature for heating and evaporation is 0-80°C.
[0030] According to a specific embodiment of the present invention, preferably, during the cleaning process, the size of the target surface is in the range of 0.5cm×0.5cm to 10cm×10cm.
[0031] According to a specific embodiment of the present invention, preferably, the volume of water added is 0.05-50 μL relative to the substrate area of 0.5 cm × 0.5 cm to 10 cm × 10 cm. The specific amount of water used depends on the size of the target substrate and the growth substrate.
[0032] In some specific implementations, preferably, the water is deionized water and / or ultrapure water.
[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0034] (1) In the water-based liquid-solid phase change cleaning method provided by this invention, ice can be used as a "cleaning stamp" to remove surface contaminants from two-dimensional materials. By controlling the cleaning temperature to adjust the adhesion of the ice, surface contaminants can be removed solely by adhesion without damaging the two-dimensional material. Since ice itself does not cause defects or additional contamination, this cleaning method does not damage the two-dimensional material or the substrate, thus avoiding the extreme conditions that may lead to defects in the two-dimensional material in conventional methods.
[0035] (2) The water-based liquid-solid phase change cleaning method provided by this invention can remove various contaminants, from polymers to inorganic particles. Furthermore, this cleaning method is also applicable to other surfaces, such as SiO2 / Si wafers and Si wafers, which is crucial for the semiconductor industry. The efficient and versatile cleaning method provided by this invention will contribute to the fabrication of clean two-dimensional materials and high-performance devices. Attached Figure Description
[0036] Figure 1 This demonstrates the change in the adhesion force of ice to glass at different temperatures.
[0037] Figure 2 The results show the effect of ice on two-dimensional material TMDs at different temperatures.
[0038] Figure 3 A schematic diagram of the process of cleaning contaminants from the target surface with ice.
[0039] Figure 4 Optical microscope images of graphene on a SiO2 substrate before and after ice cleaning in Example 1.
[0040] Figure 5AFM images of graphene on the SiO2 substrate before and after ice cleaning in Example 2.
[0041] Figure 6 AFM images of MoS2 on the Si substrate before and after ice cleaning in Example 3.
[0042] Figure 7 AFM images of BOS on the SiO2 substrate before and after ice cleaning in Example 4.
[0043] Figure 8 These are optical microscope images of the SiO2 / Si substrate before and after ice cleaning in Example 5.
[0044] Figure 9 AFM image of MoS2 after ice cleaning in Comparative Example 1. Detailed Implementation
[0045] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.
[0046] The cleaning effect on the target surface before and after ice cleaning can be evaluated by comparing the distribution of contaminants in photos taken before and after cleaning.
[0047] Example 1
[0048] This embodiment provides a water-based liquid-solid phase change cleaning method, the specific steps of which are as follows:
[0049] like Figure 3 As shown, a 1cm × 1cm SiO2 / Si substrate with a graphene film was placed on a temperature-controlled plate. 3μL of water was added to the substrate, and then a glass slide was placed on top, forming a glass slide-water film-SiO2 / Si substrate sandwich structure. The temperature was then lowered to -20°C and maintained at this temperature for 10 minutes. After the water film froze into an ice layer, the glass slide, along with the ice layer and contaminants (PMMA), was peeled off. Finally, the water remaining on the graphene was evaporated by heating at 60°C, thus completing the cleaning of the graphene and the SiO2 / Si substrate.
[0050] Graphene samples before and after ice cleaning, such as Figure 4 As shown, the Figure 4 Optical microscopy images show that most of the polymer residue (PMMA) on the graphene and SiO2 surfaces can be removed by ice cleaning.
[0051] Example 2
[0052] This embodiment provides a water-based liquid-solid phase change cleaning method, the specific steps of which are as follows:
[0053] A 2cm × 2cm SiO2 / Si substrate with a graphene sample attached was placed on a temperature-controlled plate. 10μL of water was added to the substrate, and then a glass slide was placed on top, forming a glass slide-water film-SiO2 / Si substrate sandwich structure. The temperature was then lowered to -15°C and maintained at this temperature for 10 minutes. After the water film froze into an ice layer, the glass slide, along with the ice layer and contaminants, was peeled off. Finally, the remaining water on the graphene was evaporated by heating at 50°C, thus completing the cleaning of the graphene and the SiO2 / Si substrate.
[0054] Graphene samples before and after ice cleaning, such as Figure 5 As shown, the Figure 5 AFM morphology images show that most of the polymer residue (PMMA) on the graphene and SiO2 surfaces can be removed by ice cleaning.
[0055] Example 3
[0056] This embodiment provides a water-based liquid-solid phase change cleaning method, the specific steps of which are as follows:
[0057] A 1cm × 1cm Si substrate with a MoS2 sheet sample attached was placed on a temperature-controlled plate. 2μL of water was added to the substrate, and then a metal plate (steel) was placed on top, forming a metal plate-water film-Si substrate sandwich structure. The temperature was then lowered to -10°C and maintained for 10 minutes. After the water film froze into an ice layer, the metal plate, along with the ice layer and contaminants (PMMA), was peeled off. Finally, the remaining water on the MoS2 was evaporated by heating at 40°C, thus completing the cleaning of both the MoS2 and the Si substrate.
[0058] Molybdenum disulfide samples before and after ice cleaning, such as Figure 6 As shown, the Figure 6 AFM morphology images show that most of the polymer residue (PMMA) on the MoS2 sheet can be removed by ice cleaning.
[0059] Example 4
[0060] This embodiment provides a water-based liquid-solid phase change cleaning method, the specific steps of which are as follows:
[0061] A 1cm × 1cm SiO2 substrate with a two-dimensional Bi2O2Se (BOS) sample was placed on a temperature-controlled plate. 1μL of water was added to the substrate, and then a glass slide was placed on top, forming a glass slide-water film-SiO2 / Si substrate sandwich structure. The temperature was then lowered to -20°C and maintained at this temperature for 10 minutes. After the water film froze into an ice layer, the glass slide, along with the ice layer and contaminants (dust), was peeled off. Finally, the remaining water on the BOS was evaporated by heating at 60°C, thus completing the cleaning of the BOS and the SiO2 substrate.
[0062] BOS samples before and after ice cleaning, such as Figure 7 As shown, the Figure 7 The AFM morphology images show that the surface roughness of both the BOS and SiO2 surfaces is significantly reduced, indicating that the surfaces are cleaner.
[0063] Example 5
[0064] This embodiment provides a water-based liquid-solid phase change cleaning method, the specific steps of which are as follows:
[0065] A 3cm × 3cm SiO2 / Si substrate was placed on a temperature-controlled plate. 15μL of water was added to the SiO2 / Si substrate, and then a glass slide was placed over it, forming a glass slide-water film-SiO2 / Si substrate sandwich structure. The temperature was then lowered to -20°C and maintained at this temperature for 10 minutes. After the water film froze into an ice layer, the glass slide, along with the ice layer and contaminants (dust), was peeled off. Finally, the remaining water on the SiO2 / Si substrate was evaporated by heating at 60°C, completing the cleaning of the SiO2 / Si substrate.
[0066] SiO2 / Si substrates before and after ice cleaning, such as Figure 8 As shown, the Figure 8 Images from an optical microscope show that most of the contaminants (dust) on the SiO2 surface were removed by ice.
[0067] Comparative Example 1
[0068] This comparative example provides a water-based liquid-solid phase change cleaning method, the specific steps of which are as follows:
[0069] A 1cm × 1cm Si substrate with MoS2 flakes attached was placed on a temperature-controlled plate. 5μL of water was added to the substrate, and then a metal plate (steel) was placed on top, forming a metal plate-water film-Si substrate sandwich structure. The temperature was then lowered to -20°C and maintained for 10 minutes. After the water film froze into an ice layer, the metal plate was peeled off along with the ice layer and the PMMA contaminant. Finally, any remaining water on the MoS2 was evaporated by heating at 40°C.
[0070] Molybdenum disulfide samples before and after ice cleaning, such as Figure 9 As shown, by Figure 9 It can be seen that the molybdenum disulfide sample showed signs of damage and cracks. Therefore, for MoS2, which has a weak interaction with the substrate, ice cleaning at excessively low temperatures can easily damage the two-dimensional material.
Claims
1. A water-based liquid-solid phase change cleaning method, wherein, The method includes the following steps: (1) Place water droplets on the target surface, and then cover the water droplets on the target surface with an auxiliary substrate to compress the water droplets into a water film; (2) Lower the temperature to a clean temperature below the freezing point, so that the water film freezes into an ice layer; (3) Peel off the auxiliary substrate along with the ice layer so that the pollutants are removed with the ice layer; (4) Heat and evaporate the water remaining on the target surface to complete the cleaning of contaminants on the target surface; The cleaning temperature is 0°C to -30°C.
2. The cleaning method according to claim 1, wherein, The ice layer has a lower affinity for the target surface than it has for contaminants. The ice layer has a lower affinity for the target surface than for the auxiliary substrate; The pollutant has a lower affinity for the target surface than it has for ice.
3. The cleaning method according to claim 1, wherein, The target surface includes a two-dimensional material and / or a substrate; The two-dimensional material includes one or more of the following: graphene, hBN, MXene, two-dimensional transition metal dichalcogenides, layered transition metal oxides, and layered double hydroxides. The substrate material includes one or more of the following: SiO2 / Si wafer, Si wafer, sapphire, mica, and polymer.
4. The cleaning method according to claim 3, wherein, When the target surface is a substrate, the cleaning temperature is -5°C to -30°C.
5. The cleaning method according to claim 3, wherein, When the target surface is a two-dimensional material, the cleaning temperature is 0°C to -20°C.
6. The cleaning method according to claim 5, wherein, When the target surface is a two-dimensional transition metal dichalcogenide, the cleaning temperature is 0°C to -15°C; When the target surface is graphene, the cleaning temperature is -10°C to -20°C; When the target surface is a layered transition metal oxide, the cleaning temperature is -10°C to -20°C.
7. The cleaning method according to claim 1, wherein, The auxiliary substrate is made of one or more of the following materials: glass, quartz, and metal.
8. The cleaning method according to claim 1, wherein, The pollutants include one or more of polymers, inorganic particles, and dust.
9. The cleaning method according to claim 1, wherein, The temperature for heating and evaporation is 0-80℃.
10. The cleaning method according to claim 1, wherein, The volume of water added is 0.05-50 μL relative to a substrate area of 0.5 cm × 0.5 cm to 10 cm × 10 cm.