JP2016129220A - Manufacturing method of nanowire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide means for applying a nanowire onto a solid support member by a system that a control allowing an electric circuit onto the solid support member to be designed and manufactured is performed.SOLUTION: In a manufacturing method of a nanowire using a nucleic acid as a scaffold, a thin film of a metal-DNA composite body is applied onto a solid support member, a capillarity of coffee ring efficiency is used, nucleic acid metal nanoparticle thin film is peeled, an accumulation of the nanoparticle in an end part of a cutting part is invited, and micro to nano scale metal wires are manufactured. By performing enzymatic hydrolysis, the nucleic acid is removed, and finally a metal nanowire is obtained.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method for producing a nanowire using a nucleic acid as a scaffold. The method applies a thin film of metal-DNA complex onto a solid support. Utilizing the capillary force of the coffee ring effect, peeling the nucleic acid metal nanoparticle thin film induces nanoparticle accumulation at the end of the cut, thereby producing micro-to-nanoscale metal wires. In additional embodiments, the present invention uses enzymatic hydrolysis to remove nucleic acids and obtain final metal nanowires. The present invention further provides a chip comprising an electrical circuit manufactured using the method of the present invention.

  Deoxyribonucleic acid (DNA) template synthesis has been utilized for making metal micro / nanowires for the past 20-30 years. Despite considerable success, the high throughput and controllability aspects of the fabrication process remain major obstacles. In this work, we present a novel scribing or “writing” method for creating micro-to-nanoscale silver (Ag) wires on silicon (Si) wafers using natural capillary forces. The coffee ring drying effect draped by capillary forces allows the diffusion of Ag loaded DNA molecules towards the end of the scribing resulting in deposition along the scribed pattern. This is followed by removal of the DNA scaffold using enzyme-assisted etching, leaving an Ag wire on the wafer. This technology is expected to improve current metal nanopatterns and DNA-assisted formation of nanostructures towards potential applications in nanoelectronics.

  Micro- and nanostructured DNA-assisted formation has been extensively studied for potential applications in various fields over the years. These structures, including metal wires such as Ag, exhibit exceptional spatial resolution and flexibility. Such properties are due to the particularly specific nature of the DNA strand that specifically synthesizes metal nanoparticles along its backbone 4. As such, DNA molecules allow selective metal binding that exhibits flexible nanotemplate synthesis capabilities. Coupled with its self-complementary nature, DNA electronics provides the right tool for the production of conductive wires with resolutions that cannot be achieved using conventional microelectronic technology. However, some major problems related to the high throughput industrialization of DNA assisted metal wire patterns remain unresolved. The most important, flexible “drawing” capabilities and controllability should be addressed first, followed by lowering the cost and complexity of the processes involved. Most recently, some sophisticated design architectures have been proposed for overcoming these obstacles, which greatly emphasizes the operation and repeatability of pattern alignment. However, these methods still lack the critical steps necessary to produce with industrial-level control and precision that allows a commercially viable production capacity.

  The object of the present invention is therefore based on DNA scaffolds by providing a means for applying nanowires on a solid support in a controlled manner that allows the design and manufacture of electrical circuits on the solid support. It is to enable the commercially viable production of metal nanowires, thereby enabling the production of silicon chips.

The above-described problem is a method for producing a micro / nanowire on a support material, and the step (a) provides a solid support material.
(B) applying a liquid composition comprising a nucleic acid and a metal to the surface of the nanoparticle support material, and having a surface having at least one region covered by the liquid composition and at least one region not covered by the liquid composition Obtaining a solid support material having, thereby producing micro / nanowires at the end between the region covered by the liquid composition and the region not covered by the liquid composition;
(C) optionally removing nucleic acids;
This is solved in a first aspect by the method comprising:

Preferably, the metal is selected from platinum, iron, cobalt, nickel, gold, silver, copper, iron oxide, copper oxide, zinc oxide and alloys thereof, preferably silver (Ag).
In a preferred embodiment, the nucleic acid is selected from single stranded (ss) or double stranded (ds) DNA, PNA or RNA, preferably double stranded DNA.

In one preferred embodiment, it is essential to carry out method step (c). Also preferably, step (c) is performed using an enzyme etch, preferably a nuclease enzyme, most preferably a deoxyribonuclease.
In the context of the invention described herein, the solid support material is preferably Si, preferably a Si wafer.
In one additional embodiment, a surface tension reducing agent, preferably a surfactant, is added to the liquid composition.

With respect to step (b), this step applies the liquid composition onto the solid support and then removes a portion of the liquid composition from the surface and at least one region covered with the liquid composition and the liquid composition Preferably, the method includes a sub-step of obtaining a solid support material having a surface having at least one region not covered by. Removal is ideally accomplished by stripping, cutting or wiping off the liquid composition. Peeling, cutting or wiping off the liquid composition in the context of this specification means removing the liquid composition to the level of a solid support.
Therefore, as described below, the method of the present invention provides an easy method for applying a predetermined pattern of metal nanowires onto a solid support such as a silicon wafer. The predetermined pattern using the stripping method may preferably be a circuit such as an electrical circuit.

  In one embodiment of the method in (b), after the liquid composition is applied to the surface of the solid support, the liquid composition is dried to obtain a gel-like thin film of metal nanoparticles and nucleic acids on the surface of the solid support. . This may be facilitated by the addition of a desiccant such as a solvent, preferably ethanol. For example, the drying may preferably be air drying for at least 1, 2, 3, 4, 5, 6 or 7 hours or longer. As an alternative to drying, the liquid composition may be applied to the solid support in the form of a gel or thin film. An advantage of using a gel-like or thin film-like composition of nucleic acid / metal nanoparticles is that such a thin film can be easily peeled off the surface, thereby producing a controlled edge. The shape of the manufactured end is a template for a later nanowire. Thus, the sharper the end, the higher the possible density of nanowires on the solid support.

  The principle underlying the present invention is described in more detail below. In general, micro / nanowires are produced by diffusing nucleic acid / metal-nanoparticles to the ends. By diffusing towards the end, the nucleic acid-metal material accumulates at the end and forms a wire structure. Diffusion is promoted by the so-called “coffee ring effect”.

The subject of the present invention is further a method for producing a silicon wafer having micro / nanowires, comprising the step (a) preparing a silicon wafer,
(B) providing a liquid composition comprising a nucleic acid and metal-nanoparticle complex;
(C) applying the liquid composition onto the surface of the silicon wafer;
(D) drying the silicon wafer to obtain a silicon wafer having a nucleic acid / metal-nanoparticle thin film on its surface;
(E) removing a part of the nucleic acid / metal-nanoparticle thin film from the surface of the silicon wafer, and producing an end of the thin film on the surface of the silicon wafer;
(F) optionally removing nucleic acids by hydrolysis, preferably enzymatic hydrolysis, most preferably by using deoxyribonuclease,
Which is solved by the above method.

Preferably, step (e) includes peeling or wiping the thin film from the surface of the silicon wafer (see above).
As already described above, step (f) is preferably essential.
An additional aspect of the present invention further relates to a solid support or silicon wafer manufactured using the methods described herein.
Also provided is a method of manufacturing an electrical circuit chip that includes performing the method previously described herein.

Another aspect relates to a computer comprising a solid support, silicon wafer or chip of the present invention.
And one aspect relates to micro / nanowires manufactured using the method of the present invention.
Although the invention has been specifically described according to some of its preferred embodiments, the following examples serve only to illustrate the invention, and illustrate the principles of its broadest interpretation and equivalent construction. And is not intended to be limited to within limits.

Figure 1: Atomic force microscope imaging. Contact mode AFM imaging illustrating (a) before and after (b) enzyme etching and (c) height profile and (c) optical image of three-dimensional structure of Ag wire. Figure 2: Elemental composition analysis. Images (a), (b) and (c) show the distribution of Ag nanoparticles on the Si wafer. The graph demonstrates the Ag distribution measured at the green dots representing different points across the wafer substrate; inside the thin film, on the wire and on the cut.

Detailed Description of the Invention In the present invention, we have used two novel ideas to help overcome these obstacles; capillary force induction of DNA-Ag molecules towards controlled scribing Flow and enzyme etching of DNA scaffold material on Si wafer. The proposed technique takes advantage of the self-assembled nature of DNA-Ag nanoparticle (NPs) thin films before scribing. The capillary force as a result of the “dry” effect then induces NPs to transition to scribing to form a metal-DNA pattern on the thin film.

  Enzyme etching is then used to remove unwanted DNA material and only Ag wires are obtained on the wafer. Atomic force microscopy (AFM) measurements confirm this and show a granular wire structure, while scanning electron microscopy-energy dispersive x-ray (SEM-EDX) demonstrates the deposition of significantly higher amounts of AgNPs on the wire To do. These observations confirm the metal regions of the surface scan and show Ag aggregates with submicron to nanometer dimensions. Thus, potential applications of our method can be used in the fabrication of micro-to-nanometer resolution patternable metal wires. We will then use these to reduce inter-element pacing and increase interconnect packing in the controlled manner necessary for miniaturization in electronics. Could be used.

Materials and methods
A silicon wafer having a silicon wafer substrate preparation size of 2.0 inches × 0.5 mm (single-side polished, <100>, n-type, undoped) was purchased from Sigma, UK and stored in a refrigerator before use (about 4 ° C). The wafers used in this study were used only once and were new from the supplier, so no further cleaning was necessary.

Incubation of silver nanoparticles 0.5 ml deionized water (18.2 MΩ.cm) was mixed in a vial containing lyophilized pBR322 DNA (MW 2.9 × 10 ⁶ Da) from E. coli RR1 (Sigma, UK) did. 400 μL of this DNA solution was mixed with 400 μL of Ag nanoparticle dispersion (10 nm particle size, 0.2 mg · mL ⁻¹ ) in aqueous buffer (Sigma, UK) to form a hybrid solution. This solution was then incubated overnight to allow the metallic silver aggregate to bind to the DNA molecules.

Preparation of DNA-AgNPs wire Using a micropipette, transfer 50 μL of DNA-AgNPs solution onto a silicon wafer. After 15 minutes, 1 drop of ethanol (10 μL) was applied onto the drop and left to dry overnight in air. Scribing was performed using a surgical blade and visual spacing or cuts were observed. The removal of the DNA scaffold was then preceded by enzymatic hydrolysis. A silicon wafer containing a DNA-AgNp thin film was prepared from 2 mg. It was immersed in 10 mM solution of 1 mM potassium phosphate buffer pH 7.4 containing mL- ¹ deoxyribonuclease I (Sigma, UK) and 2 mM magnesium chloride (Sigma, UK) for enzyme activation.

AFM imaging AFM surface and electrical imaging (Veeco Dimension 3100) were performed using an AFM probe (Model SCM-PIC with antimony (n) doped Si) with a contact mode tip.
SEM-EDX measurement elemental analysis was performed using an SEM-EDX instrument model Verios 460 from FEI, USA.

Example 1: Fabrication of Ag microwires The fabrication process involves three major steps; DNA-AgNPs suspension self-assembly, circuit scribing or drawing, and DNA removal using an enzymatic hydrolysis process (8). The first step involves placing a drop (50 μL) of this suspension on a clean Si wafer followed by application of about 10 μL of ethanol and drying in air. Ethanol acts on the concentration and dehydration of DNA and imparts them mechanical stability 9 on the wafer. And gel-like thin film residues were observed after evaporation of water molecules when allowed to dry overnight. Thereafter, cutting was performed to the wafer level using a scribing method and the edges were effectively pulled apart. Due to the gel-like nature of the hybrid thin film, the flowability of flexible DNA-AgNPs occurs towards the cut. This was demonstrated by the higher material density observed in FIG. 1a due to capillary flow from the end of the cut. Enzyme etching of the DNA scaffold was then performed using the enzyme deoxyribonuclease (8), the optical image shows the difference; in FIG. 1b, a cleaner looking substrate is seen after the enzyme treatment.

Example 2: Surface morphology of silver wire FIG. 1 clearly shows the structure of the fabricated Ag wire. The optical image shows a higher material density at the ends of both sides of the scribing (FIG. 1a). This observation is consistent with the “coffee ring” effect 10 seen in dry droplets of the solution as a result of capillary forces, resulting in a continuous granular wire structure (FIGS. 1c and d). Measurements show average height values of approximately 200-400 nm with occasional steep peaks up to 800 nm, while widths of less than 10 μm were measured. These values clearly indicate the successful fabrication of submicron to nanometer scale dimensions.

Example 3: SEM-EDX analysis We also investigated the elemental composition along different regions of the wafer substrate to demonstrate the successful fabrication of Ag wires (Figure 2). The results show a significantly higher percentage of Ag along the wire structure compared to the other regions. FIG. 2 highlights the distribution of Ag inside the wire (a), thin film (b) and on the cut area. As expected, metal nanoparticle deposition could only be seen along the wire structure and was rarely seen in the other two regions due to capillary forces.

  The technology we have described in this study introduces two new breakthroughs to overcome the major obstacles currently hindering progress in DNA-assisted fabrication of metal micro and nanowires. Our method has several advantages over others, mainly the sophisticated use of diffusion driven by the natural capillary force of DNAAgNP towards a physically made incision or scribing, followed by an Ag wire Biochemical enzyme etching of DNA scaffolds using deoxyribonuclease to obtain structure only. The latter process introduces an important advancement in preparing clean wire-only substrates for incorporation into nanoelectronic architectures. The first step, on the other hand, differs from the previously reported arbitrary wire and pattern creation (6, 7, 11-13) in that it is highly controllable in “draw” metal wires by utilizing capillary forces. And allow flexibility.

  Capillary force is induced by the comparative difference that exists along the droplet, so that the water evaporating from the edge is replenished with a large amount of water. Because of this phenomenon, DNA molecules “pull” and deposit AgNPs towards the ends, resulting in the formation of wires. The evaporation process also induces Marangoni convection in the droplets that are harmful to deposit DNAAgNPs along the edges (14). Strong Marangoni convection causes redistribution of particles back to the center. This convective disruption due to the addition of surfactants that reduce surface tension can increase deposition along the wire region, improving the structural and electrical properties of the Ag wire.

  “Drawing” resolution is also greatly improved and can be easily manipulated by utilizing lithography and other nanoscale techniques (15-16). Combined with the ease of drawing patterns using this method, nanometer-sized wire resolution may further facilitate research into single molecule electronics. In addition, this proposed assembly and patterning procedure allows for lower cost and lower process complexity flexibility compared to previous studies (1-3, 6, 7, 11-13). Become. As such, we anticipate the outcomes of these current discoveries with a reduction in drawing width, greatly facilitating the development of practical nanopatterning and nanoelectronics in general.

References

Claims (24)

A method for producing micro / nanowires on a support material, the step (a) providing a solid support material,
(B) applying a liquid composition comprising nucleic acids and metal nanoparticles to the surface of the support material, and having a surface having at least one region covered by the liquid composition and at least one region not covered by the liquid composition Obtaining a solid support material having, thereby producing micro / nanowires at the end between the region covered by the liquid composition and the region not covered by the liquid composition;
(C) optionally removing nucleic acids;
Said method.   The method according to claim 1, wherein the metal is selected from platinum, iron, cobalt, nickel, gold, silver, copper, iron oxide, copper oxide, zinc oxide and alloys thereof, preferably silver (Ag).   The method according to claim 1 or 2, wherein the nucleic acid is selected from single-stranded (ss) or double-stranded (ds) DNA, PNA or RNA, preferably double-stranded DNA.   The method according to any one of claims 1 to 3, wherein step (c) is essential.   The method according to any one of claims 1 to 4, wherein (c) is performed using enzyme etching, preferably nuclease enzyme, most preferably deoxyribonuclease.   The method according to any one of claims 1 to 5, wherein the solid support material is Si, preferably a Si wafer.   (B) applies the liquid composition onto the solid support and then removes part of the liquid composition from the surface and is not covered by the liquid composition and at least one region covered by the liquid composition 7. A method according to any one of the preceding claims comprising the step of obtaining a solid support material having a surface having at least one region.   8. The method of claim 7, wherein removal is accomplished by peeling, cutting or wiping the liquid composition.   The method according to claim 7 or 8, wherein the predetermined pattern is a circuit.   In (b), after applying the liquid composition to the surface of the solid support, the liquid composition is dried to obtain a gel-like thin film of metal nanoparticles and nucleic acid on the surface of the solid support. 10. The method according to any one of items 9.   11. A process according to claim 10, wherein drying is accelerated by adding a drying agent such as a solvent, preferably ethanol.   12. A process according to claim 11, wherein the drying is preferably air drying for at least 1, 2, 3, 4, 5, 6 or 7 hours or longer.   13. A method according to any one of claims 1 to 12, wherein the liquid composition is applied to a solid support in the form of a gel or a thin film.   14. A method according to any one of the preceding claims, wherein the micro / nanowire is produced by diffusing nucleic acid / metal-nanoparticles at the ends. A method for producing a silicon wafer having micro / nanowires, comprising: (a) preparing a silicon wafer;
(B) providing a liquid composition comprising a nucleic acid and metal-nanoparticle complex;
(C) applying the liquid composition onto the surface of the silicon wafer;
(D) drying the silicon wafer to obtain a silicon wafer having a nucleic acid / metal-nanoparticle thin film on its surface;
(E) removing a part of the nucleic acid / metal-nanoparticle thin film from the surface of the silicon wafer, and producing an end of the thin film on the surface of the silicon wafer;
(F) optionally removing nucleic acids by hydrolysis, preferably enzymatic hydrolysis, most preferably by using deoxyribonuclease,
Said method.   The method of claim 15, wherein (e) comprises peeling or wiping the thin film from the surface of the silicon wafer.   The metal according to claim 15 or 16, wherein the metal is selected from platinum, iron, cobalt, nickel, gold, silver, copper, iron oxide, copper oxide, zinc oxide and alloys thereof, preferably silver (Ag). Method.   18. A method according to any one of claims 15 to 17, wherein the nucleic acid is selected from single stranded (ss) or double stranded (ds) DNA, PNA or RNA, preferably double stranded DNA.   The method according to any one of claims 15 to 18, wherein step (f) is essential.   The method according to any one of claims 15 to 19, wherein the micro / nanowire is produced by diffusing a nucleic acid / metal-nanoparticle complex to the end of the thin film.   A solid support or a silicon wafer manufactured using the method according to claim 1.   21. A method of manufacturing an electrical circuit chip, comprising performing the method according to any one of claims 1-20.   23. A computer comprising a solid support, silicon wafer or chip according to claim 21 or 22.   A micro / nanowire manufactured using the method according to any one of claims 1-14.