Nanoparticle large-area patterning preparation method

Abstract

The invention discloses a nano-particle large-area patterning preparation method by combining electric field regulation and control with a precision displacement table, and relates to the technical field of nano processing, the method comprises the following steps: placing a conductive substrate covered with a low-surface-energy electret thin layer on a double-shaft electric control displacement table, writing charges through a conductive atomic force microscope probe connected with an adjustable high-voltage power supply, and then carrying out electric field control on the conductive substrate; the displacement table is synchronously controlled to move to form a high-surface-energy nano pattern, and then nano particles are introduced to be selectively adsorbed to a pattern area. The method solves the problems of non-specific adsorption, strong external field / template dependence and difficulty in giving consideration to high precision and large-area preparation in the prior art, has the advantages of adjustable pattern, high cleanliness, wide application range and the like, and is suitable for large-scale preparation of nano structures in the fields of electronics, photoelectricity and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of nanofabrication, and particularly to a method for large-area nanoparticle patterning. BACKGROUND

[0002] With the rapid development of the fields of electronic science, photon science, optoelectronic science and biological science, higher requirements are put forward for the processing precision, preparation efficiency and cost control of nanostructures, and in particular, large-area, high-selectivity nanoparticle patterning technology has become a research hotspot.

[0003] The assembly and patterning of nanoparticles are the core links of nanostructure preparation. In the prior art, common schemes mainly include two types: Surface chemical modification method: a nano pattern with different chemical properties is prepared on the surface of a substrate by micro-nano processing technology, and nanoparticles are introduced by chemical reaction or chemical adsorption. However, this method relies on uncontrollable chemical processes, which can easily cause non-specific adsorption of nanoparticles in non-target areas, resulting in contamination of nanostructures and affecting the pattern precision and cleanliness.

[0004] External field / template assisted assembly method: nanoparticles are induced to assemble in a large-area region by using an external field (such as an electric field or a magnetic field) or a physical template. However, this method has strong dependence on templates or external fields, and it is difficult to flexibly adjust the parameters such as the period and shape of the pattern, and it is difficult to meet the needs of high-precision positioning and large-area preparation - high-precision positioning technology (such as atomic force microscope) is usually limited to microscopic scale, while large-area assembly technology is difficult to achieve pattern control with nanoscale resolution.

[0005] In addition, nanoparticles in solution can be induced to aggregate in a predetermined area by an electric field, the feedback system of an atomic force microscope can maintain stable positioning of the probe, an electrically controlled displacement table can achieve stable movement of the substrate over a large range, and a signal generator can generate a controllable voltage signal. These known technologies provide a basis for nanofabrication, but the prior art has not effectively integrated them to solve the above-mentioned defects. Therefore, there is an urgent need for a nanoparticle patterning scheme that has high precision, large area, low non-specific adsorption and high adjustability. SUMMARY

[0006] This section aims to summarize some aspects of the embodiments of the present application and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of the specification to avoid obscuring the purpose of this section, abstract and title, and such simplifications or omissions cannot be used to limit the scope of the present application.

[0007] Therefore, the purpose of the present application is to provide a method for large-area nanoparticle patterning to solve the problems raised in the background art.

[0008] To solve the above technical problems, according to one aspect of the present application, the present application provides the following technical solutions: A nanoparticle large-area patterning preparation method, steps are as follows: S1, providing a conductive substrate, the surface of the conductive substrate is covered with a low surface energy electret thin layer, the conductive substrate is placed on a biaxial electrically controlled displacement table; S2, using a conductive probe of a conductive atomic force microscope as a charge writing tool, connecting the conductive probe to the positive pole of an adjustable high-voltage power supply, connecting the conductive substrate to the negative pole of the adjustable high-voltage power supply and grounding; S3, controlling the conductive probe to be stable on the substrate surface, applying a high-voltage signal through the adjustable high-voltage power supply, and controlling the biaxial electrically controlled displacement table to drive the conductive substrate to move in a preset trajectory in the X-Y plane, and the movement of the biaxial electrically controlled displacement table is coordinated with the high-voltage signal in time and space, so that the area of the electret thin layer surface written with electric charge is chemically modified to form a nanometer pattern with high surface energy; S4, introducing a system containing nanoparticles to the surface of the conductive substrate, so that the nanoparticles are selectively adsorbed to the nanometer pattern area with high surface energy, and the nanoparticle large-area patterning preparation is completed.

[0009] As a preferred scheme of the nanoparticle large-area patterning preparation method, in step S2, the adjustable high-voltage power supply is formed by a signal generator and a high-voltage amplifier, the signal generator is used to generate a voltage signal with a preset period and duty cycle, and the high-voltage amplifier is used to amplify the voltage signal to obtain the high-voltage signal.

[0010] As a preferred scheme of the nanoparticle large-area patterning preparation method, in step S1, the material of the electret thin layer is at least one of a fluorine-containing electret compound, a fluorine-containing electret polymer, a ferroelectric material or a polymer material, and the electret thin layer is attached to the surface of the conductive substrate by physical spraying or chemical deposition.

[0011] As a preferred scheme of the nanoparticle large-area patterning preparation method, in step S3, the coordination of the biaxial electrically controlled displacement table and the adjustable high-voltage power supply is realized through a computer control system, the computer control system presets the movement speed, trajectory of the biaxial electrically controlled displacement table and the parameters of the high-voltage signal, and synchronously controls the two to run to form a preset nanometer pattern.

[0012] As a preferred scheme of the nanoparticle large-area patterning preparation method, in step S4, the nanoparticle-containing system is a nanoparticle solution or a nanoparticle gas, and the introduction mode is at least one of spin coating, coating, pulling, or gas phase spraying.

[0013] As a preferred scheme of the nanoparticle large-area patterning preparation method, in step S1, the conductive substrate is a silicon wafer or an ITO glass sheet, and the thickness of the electret thin layer is in the nanometer to micrometer range.

[0014] As a preferred scheme of the nanoparticle large-area patterning preparation method, in step S3, the nanopattern formed is measured for potential distribution by a Kelvin probe force microscope, or is characterized for surface energy difference by a tangential force mode of an atomic force microscope.

[0015] As a preferred scheme of the nanoparticle large-area patterning preparation method, the high-voltage signal has a period of 0.1 ms-100 ms and a duty cycle of 10%-90%, and the biaxial electrically controlled displacement table has a movement speed of 0.1 μm / s-10 μm / s and a movement range of not less than 1 mm.

[0016] As a preferred scheme of the nanoparticle large-area patterning preparation method, in step S4, the driving force for selective adsorption of the nanoparticles includes a surface energy difference between the high-surface-energy region and the low-surface-energy region and a Coulomb force or gradient force of the nanoparticles generated by the electric field of the charge writing region.

[0017] As a preferred scheme of the nanoparticle large-area patterning preparation method, in step S3, the conductive atomic force microscope maintains the conductive probe at a preset height on the substrate surface by a feedback system, and the preset height is in the nanometer range.

[0018] Compared with the prior art, the present application has the beneficial effects that: 1. The present application uses a substrate covered with a low-surface-energy electret thin layer, and only through charge writing, a specific region is chemically modified into a high-surface-energy nanopattern. Nanoparticles are selectively adsorbed only in the high-surface-energy region due to the surface energy difference, and the low-surface-energy non-pattern region does not adsorb particles, thereby fundamentally avoiding non-specific adsorption caused by uncontrollable reaction in the prior art chemical adsorption method, and significantly improving the cleanliness and pattern accuracy of the nanopattern.

[0019] 2、The application generates controllable periodic high-voltage signals (adjustable voltage, period, duty cycle) by combining a signal generator with a high-voltage amplifier, and accurately cooperates with the motion trajectory and speed of a double-shaft electrically controlled displacement table, without relying on a physical template to "directly write" any designed nano-pattern (such as a straight line, a curve, a dot matrix, etc.). The pattern parameters can be flexibly adjusted through a program, solving the problem of non-adjustable patterns and strong dependence in the traditional external field / template assisted method.

[0020] 3、The application innovatively integrates the nanoscale positioning accuracy of an atomic force microscope (providing microscale charge writing control) and the large-range motion capability of an electrically controlled displacement table (providing macro-scale substrate movement), and realizes accurate coupling of the two in time and space through a computer system. This "macro-micro cooperation" mechanism not only guarantees the sub-micron resolution of the nano-pattern, but also supports large-area preparation of more than one centimeter, breaking through the bottleneck of "difficulty in balancing high precision and large area" in the prior art.

[0021] 4、The adsorption of nanoparticles is based on physical action (surface energy difference and electric field induction), and has no special requirements for the chemical functional groups on the surface of the particles, and is suitable for nanoparticles of various materials (such as metal, semiconductor, polymer particles, etc.); at the same time, the diversity of the electret thin layer material (such as fluorine-containing polymer, ferroelectric material) can flexibly adjust the surface energy of the substrate, further expanding the application scenarios of the scheme.

[0022] 5、The application synchronously controls the high-voltage signal and the displacement table motion through a preset program, realizes mask-free, direct writing type nano-processing, reduces the template preparation step in the traditional photolithography process, reduces the cost, and the pattern design can be quickly iterated through software, significantly improving the preparation efficiency and flexibility. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the application, the application will be described in detail below with reference to the drawings and detailed embodiments. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor. Among them: Figure 1 The connection structure schematic diagram of the double-shaft electrically controlled displacement table, the conductive probe and the adjustable high-voltage power supply provided by the application; Figure 2 The local potential diagram of the parallel charge stripe provided by the application; Figure 3 The global dark field diagram after the gold nanoparticles are assembled provided by the application; Figure 4 The local dark field diagram after the gold nanoparticles are assembled provided by the application. Detailed Implementation

[0024] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0025] This invention provides a method for large-area patterning of nanoparticles, which solves the problems of non-specific adsorption, strong dependence on external field / template, and difficulty in achieving both high precision and large-area preparation in existing technologies. It has advantages such as adjustable patterns, high cleanliness, and wide applicability, and is suitable for the large-scale preparation of nanostructures in fields such as electronics and optoelectronics. The method for large-area patterning of nanoparticles is described in detail below through Examples 1-2.

[0026] Example 1: Preparation of striped patterned gold nanoparticles on fluorine-containing electret-modified silicon wafers Step 1: Substrate Pretreatment 1) Select silicon wafers as conductive substrates, and ultrasonically clean them with acetone, ethanol and deionized water for 10 minutes in sequence to remove surface impurities. Dry them with nitrogen gas and set aside for later use. 2) Prepare a 3% by mass of fluoropolymer electret material and coat it onto the silicon wafer surface by spin coating: set the spin coating speed to 3000 rpm and the time to 30 seconds to form a thin layer of fluoropolymer electret material with a thickness of about 100 nm. The fluoropolymer electret material has low surface energy (hydrophobic properties) and can stably retain charge as an electret, thus forming a low surface energy substrate.

[0027] Step 2: Equipment Setup and Parameter Settings 1) such as Figure 1 As shown, the conductive probe (200) of the conductive atomic force microscope (c-AFM) is connected to the positive terminal of the adjustable high voltage power supply (300), and the silicon substrate is connected to the negative terminal of the power supply and grounded. The adjustable high voltage power supply (300) is composed of a signal generator (model: Agilent 33220A) and a high voltage amplifier (model: Trek 609E-6) and is used to generate periodic high voltage signals. 2) Fix the pretreated substrate onto a dual-axis electrically controlled displacement stage (100) (model: PI M-111.1DG). Connect the dual-axis electrically controlled displacement stage (100) to the computer control system. Set the x-axis movement speed to 1 μm / s and the unidirectional movement distance to 1 mm. After the y-axis and x-axis movements are completed, move quickly by 5 μm (to avoid pattern overlap). Repeat the x-axis movement process. High-voltage signal parameters: The signal generator is set with a period of 25ms and a duty cycle of 25%. After being amplified by the high-voltage amplifier, the signal is output to the probe to achieve periodic charge writing.

[0028] Step 3: Writing Nanocharge Patterns 1) Start the atomic force microscope and use its feedback system to stably suspend the conductive probe (200) on the surface of the fluorine electret thin film (at a distance of about 5 nm) to ensure that the relative position of the conductive probe (200) and the substrate is stable; 2) The high-voltage power supply (300) and the dual-axis electrically controlled displacement stage (100) are started simultaneously. Under the action of high voltage, the conductive probe (200) writes charges onto the substrate surface. At the same time, the x-axis moves at a preset speed to form a linear charge pattern along the x-direction. After the x-axis movement ends, the y-axis moves rapidly by 5 μm. The above process is repeated, and finally, five parallel charge stripes with a length of 1 mm and a spacing of 5 μm are formed on the substrate surface. The local potential diagram of the parallel charge stripes is shown in the figure. Figure 2 As shown; 3) Characterization of charge patterns: Kelvin probe force microscopy (KPFM) measurements showed that the potential of the written charge region was significantly higher than that of the unwritten region, proving the formation of high surface energy nanopatterns; tangential force mode observation by atomic force microscopy showed that the frictional force of the written charge region was significantly greater than that of the unwritten region, verifying the difference in surface energy (high surface energy regions are more likely to adsorb particles).

[0029] Step 4: Selective assembly of gold nanoparticles 1) Prepare a gold nanoparticle solution with a concentration of 0.1 mg / mL (particle size 50 nm, dispersed in deionized water), and introduce it onto the substrate surface by spin coating: set the spin coating speed to 2000 rpm and the time to 40 seconds; 2) Under electrostatic induction, gold nanoparticles are driven by the Coulomb force and gradient force in the charge pattern region to accumulate in the high surface energy charge region; at the same time, due to the low surface energy of the non-patterned region of the fluorine electret, the particles are selectively adsorbed only in the charge stripe region, forming the gold nanoparticle stripe pattern.

[0030] Step 5: Observation of assembly results Observation using a dark-field microscope, such as Figure 3 As shown, the global image displays five consecutive gold nanoparticle stripes (1 mm in length), as... Figure 4 As shown in the magnified image, the stripe width is approximately 200 nm, and the particles are evenly distributed within the stripes with no obvious non-specific adsorption phenomenon, demonstrating the high selectivity and cleanliness of the present invention.

[0031] Example 2: Lattice patterning of silver nanoparticles on ITO glass This embodiment uses similar equipment and processes as in Example 1, but adjusts parameters to prepare lattice-like nanopatterns. The specific differences are as follows: Substrate selection: ITO glass (conductive glass) was selected as the substrate, and a thin layer of polytetrafluoroethylene (PTFE) electret (50nm thick) was coated on the surface. It was prepared by chemical deposition and also has low surface energy characteristics.

[0032] Displacement table motion parameters: set the x-axis and y-axis to step motion, the x-axis moves 1 μm each time, and the y-axis moves 1 μm after 10 ms of staying, forming a 100x100 dot pattern, with a total coverage area of 100 μm x 100 μm.

[0033] High-voltage signal parameters: the signal generator is set to a period of 10 ms and a duty cycle of 50%, ensuring that the charge writing amount of each dot array is consistent.

[0034] Nanoparticle introduction method: silver nanoparticle solution (concentration 0.05 mg / mL) is introduced by the pull-up method at a pulling speed of 5 mm / min, so that the particles uniformly cover the substrate and selectively adsorb to the charge dot array area.

[0035] The results show that silver nanoparticles form discrete dots with a diameter of about 500 nm at the charge dot array, with no obvious agglomeration or adsorption to non-target areas, proving the universality of the present application for different substrates, particle types, and pattern shapes.

[0036] Although the present application has been described above with reference to embodiments, various modifications can be made to it and components thereof can be replaced with equivalents without departing from the scope of the present application. In particular, each feature in the disclosed embodiments of the present application can be used in any combination with one another, provided that there is no structural conflict, and the fact that these combinations are not described in the present specification is merely for the sake of brevity and resource conservation. Therefore, the present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for preparing a large-area nanoparticle pattern, characterized by, The steps are as follows: S1, providing a conductive substrate, the surface of the conductive substrate is covered with a low surface energy electret thin layer, the conductive substrate is placed on a biaxial electrically controlled displacement table (100); S2, using a conductive atomic force microscope as a charge writing tool, the conductive probe (200) is connected to the positive electrode of an adjustable high-voltage power supply (300), and the conductive substrate is connected to the negative electrode of the adjustable high-voltage power supply (300) and grounded; S3, control the conductive probe (200) to be stable on the substrate surface, apply a high-voltage signal through the adjustable high-voltage power supply (300), and control the biaxial electrically controlled displacement table (100) to drive the conductive substrate to move in the X-Y plane according to a preset trajectory, and the movement of the biaxial electrically controlled displacement table (100) is coordinated with the high-voltage signal in time and space, so that the area of the electret thin layer surface written with electric charge is chemically modified to form a nano pattern with high surface energy; S4, introducing a nano-particle-containing system to the surface of the conductive substrate, so that the nano-particles are selectively adsorbed on the nano pattern area with high surface energy, and the large-area nano-particle patterning is completed.

2. The method according to claim 1, wherein In step S2, the adjustable high-voltage power supply (300) is formed by a signal generator and a high-voltage amplifier, the signal generator is used to generate a voltage signal with a preset period and duty cycle, and the high-voltage amplifier is used to amplify the voltage signal to obtain the high-voltage signal.

3. The method of claim 1, wherein the nanoparticles are patterned over a large area. In step S1, the material of the electret thin layer is at least one of fluorine-containing electret compound, fluorine-containing electret polymer, ferroelectric material or polymer material, and the electret thin layer is attached to the surface of the conductive substrate by physical spraying or chemical deposition.

4. The method of claim 1, wherein the nanoparticles are patterned over a large area. In step S3, the coordination of the biaxial electrically controlled displacement table (100) and the adjustable high-voltage power supply (300) is realized through a computer control system, the computer control system presets the movement speed, trajectory of the biaxial electrically controlled displacement table (100) and the parameters of the high-voltage signal, and synchronously controls the two to run to form a preset nano pattern.

5. The method of claim 1, wherein the nanoparticles are patterned over a large area. In step S4, the nano-particle-containing system is a nano-particle solution or a nano-particle gas, and the introduction method is at least one of spin coating, coating, pulling method or gas phase spraying method.

6. The method of claim 1, wherein the nanoparticles are patterned over a large area. In step S1, the conductive substrate is a silicon wafer or an ITO glass sheet, and the thickness of the electret thin layer is nanoscale to micrometer scale.

7. The method of claim 1, wherein the nanoparticles are patterned over a large area. In step S3, the nano pattern formed is measured by a Kelvin probe force microscope for its potential distribution, or characterized by a tangential force mode of an atomic force microscope for its surface energy difference.

8. The method of claim 2, wherein the nanoparticles are patterned over a large area. The period of the high-voltage signal is 0.1ms-100ms, the duty cycle is 10%-90%, the movement speed of the biaxial electrically controlled displacement table (100) is 0.1μm / s-10μm / s, and the movement range is not less than 1mm.

9. The method of claim 1, wherein the nanoparticles are patterned over a large area. In step S4, the driving force of the selective adsorption of the nano-particles includes the surface energy difference between the high surface energy area and the low surface energy area and the coulomb force or gradient force of the electric field generated in the charge writing area on the nano-particles.

10. The method of claim 1, wherein the nanoparticles are patterned over a large area. In step S3, the conductive atomic force microscope maintains the conductive probe (200) at a preset height on the substrate surface by a feedback system, and the preset height is in nanometer level.

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