KR100852684B1 - Preparation methods of the selective nanowire - Google Patents

Abstract

A manufacturing method of nanowire selectively on a desired region is provided to obtain an arranged uniform zinc oxide nanowire in a desired region in a simple process by employing aluminum layer and photoresist layer on a silicone substrate. A manufacturing method of zinc oxide nanowire(14) selectively on a desired region comprises steps of: i) forming an aluminum layer(4) on a silicone substrate(2); ii) forming a photoresist layer(6) on the aluminum layer, followed by patterning the photoresist layer; iii) forming a porous aluminum oxide layer(8) by anodic oxidation of the aluminum layer after completion of patterning; iv) forming zinc oxide seed layer by painting zinc oxide seed(12) on the silicone substrate which has the porous aluminum oxide layer; v) removing the photoresist layer and the porous aluminum oxide layer in order after the step iv) is finished; and vi) growing the painted zinc oxide seed on the silicone substrate after the step v) is finished. In step iii), apertures(10) are formed on the aluminum layer in order to paint the zinc oxide seed on the surface of the silicone substrate.

Description

Preparation method of selective zinc oxide nanowires {Preparation Methods of the Selective Nanowire}

1 is a process chart showing a method for producing zinc oxide nanowires according to the present invention.

<Description of the symbols for the main parts of the drawings>

2: silicon substrate 4: aluminum layer

6: photoresist layer 8: porous aluminum oxide layer

10: void 12: zinc oxide seed layer

14: zinc oxide nanowires

The present invention relates to a method for producing zinc oxide (ZnO), specifically a selective zinc oxide nanowire, and more particularly, after forming an aluminum layer and a photoresist layer on a silicon substrate, patterning the photoresist layer, Anodizing the aluminum layer to form a porous aluminum oxide layer, applying a zinc oxide seed on the silicon substrate of the porous aluminum oxide layer (sed) and then sequentially removing the photoresist layer and the porous aluminum oxide layer formed on the silicon substrate The present invention relates to a method of manufacturing zinc oxide nanowires comprising growing a zinc oxide seed coated on a silicon substrate from which the porous aluminum oxide layer and the photoresist layer are removed.

Nano-sized materials with small diameters have emerged as a very important field in the recent scientific community because of their new physical and chemical properties, namely their unique electrical, optical and mechanical properties. The research on nanostructures that have been conducted so far shows new possibilities such as the quantum size effect and the potential as a new optical device material of the future.

Among these nanostructures, nanowires exhibit various physical and chemical characteristics because they have a much larger surface / mass ratio than bulk materials, and can be applied to environmental materials as well as optical devices including nanoelectronic devices and semiconductor light emitting devices. In particular, in the case of semiconductor nano-compounds, not only single electron transistor (SET) devices but also new optical device materials are attracting attention.

Therefore, the use of such nanostructures, in particular nanowires, enables the implementation of more advanced and miniaturized electronic, electrochemical and optical devices, as well as the implementation of new features and structures that were previously impossible. For example, when zinc oxide is formed in the form of nanowires, it can be used as a photocatalyst using chemical reactions occurring on the surface, or as an optoelectronic device using optical properties resulting from defects on the surface.

Meanwhile, examples of nanostructures known to date include quantum dots, nano powders, nanowires, nanotubes, quantum wells, nano thin films, and nanocomposites. As described above, the above-described nanostructures may be made of various materials such as Zn, Si, Ge, GaN, GaAs, and the like, in the case of manufacturing nanostructures, particularly nanowires using zinc (Zn). Zinc oxide nanowires can be prepared by oxidizing zinc.

Here, the zinc oxide has a wide bandgap of 3.37 eV at room temperature, and has a large exciton (exciton) binding energy of 60 meV, which is greater than the thermal energy of 24 meV, thereby facilitating light emission in the ultraviolet region. Therefore, the above-described zinc oxide has attracted much attention as an optical device such as an ultraviolet light emitting diode (Ultraviolet LED) or a laser diode (LD) because of its excellent optical properties.

In particular, zinc oxide has been widely used in various fields such as high-temperature, high-voltage electrical and electronic devices, surface acoustic wave devices, piezoelectric devices, gas sensors, and transparent conductive films as broadband semiconductor materials. Although it has been utilized, in recent years, as epitaxial growth technology is developed, new application fields are being explored, and researches on a method for manufacturing zinc oxide having a low dimensional structure, particularly with respect to nano-optical devices, are being actively conducted.

As an example of a method for manufacturing a nanowire as a nanostructure made of zinc oxide, carbon thermal reduction (CVD) or chemical vapor deposition (CVD) is known, and the zinc oxide nanowires prepared using the same Applicability has been confirmed by devices and chemical sensors.

However, since the nanostructures in the form of nanowires are very fine and require a technique such as e-beam lithography to be mobilized in order to realize the device, there is a problem that alignment and assembly are not easy. Development of used device and product is not easy. Accordingly, there is an urgent need to develop a technology for forming a homogeneous nanowire so that the alignment state of the nanowire is good.

On the other hand, zinc oxide manufacturing methods of nanostructures known to date include organometallic chemical vapor deposition (MOCVD), molecular beam deposition, sol-gel deposition, sputtering, reaction evaporation, spray pyrolysis or pulse There is a laser deposition method, and as such an example, Korean Patent Publication No. 2005-0005122 discloses a method of forming zinc oxide nanowires on a surface by oxidizing zinc particles in air / atmospheric pressure, Korean Patent Publication No. 2003 -0060619 discloses a method for producing zinc oxide-based nanowires by organometallic chemical vapor deposition, and Korean Patent Laid-Open No. 2005-0010601, which discloses zinc gas produced by a reduction reaction between zinc oxide powder and graphite on a silicon substrate. A method of making a nanostructure by deposition is disclosed.

However, the aforementioned methods require complicated steps such as controlling the vacuum condition, controlling the gas partial pressure, and / or controlling the temperature, or requiring separate steps such as purchasing the specimen and pretreating the specimen. have. Therefore, in order to more easily manufacture zinc oxide nanostructures, specifically, zinc oxide nanowires, it is required to develop a process capable of manufacturing nanowires in an atmosphere similar to room temperature and / or atmospheric pressure.

In particular, in implementing zinc oxide as a device, it is important to form nanowires at a desired position in addition to good alignment and formation of homogeneous nanowires. However, when zinc oxide nanowires are formed on a silicon substrate, many nanowires are disposed in an unusable region, which is more discarded than the nanowires used in the device in the process of realizing the nanowires. It is difficult to provide.

Therefore, the formation of nanowires in the desired region as desired alignment forms not only saves wasted resources in implementing the device, but also facilitates device implementation and provides a homogeneous silicon surface in areas other than nanowires. Could be.

Accordingly, the inventors of the present invention, while repeatedly researched to overcome the above-mentioned problems, after forming an aluminum layer and a patterned photoresist layer on a silicon substrate and then anodizing the aluminum layer to form a porous aluminum oxide layer having pores formed therein. Forming a layer, applying zinc oxide seeds to the pores, removing the photoresist layer and the porous aluminum oxide layer, and growing the zinc oxide seeds on the silicon substrate from which the photoresist layer and the porous aluminum oxide layer have been removed. The present invention has been completed with the idea that a homogeneous zinc oxide nanowire having a good alignment can be produced.

The present invention was derived to overcome the above-mentioned problems, and after forming an aluminum layer and a patterned photoresist layer on a silicon substrate, anodizing the aluminum layer to form a porous aluminum oxide layer having pores formed therein, After applying zinc oxide seed, removing the photoresist layer and the porous aluminum oxide layer, and growing the zinc oxide seed to produce a homogeneous zinc oxide nanowires well aligned with a few processes in an atmosphere similar to room temperature and atmospheric pressure. There is a technical problem in providing.

The present invention comprises the steps of: i) forming an aluminum layer on a silicon substrate; Ii) a patterning step of forming and then patterning a photoresist layer on top of the aluminum layer of step iii); Iv) anodizing to form a porous aluminum oxide layer by anodizing the aluminum layer after the patterning step of step ii) is finished; Iii) applying zinc oxide seeds on the silicon substrate on which the porous aluminum oxide layer of step iv) is formed to form a zinc oxide seed layer; Iii) sequentially removing the photoresist layer and the porous aluminum oxide layer after step iii) is finished; And iii) a zinc oxide growth step of growing a zinc oxide seed coated on a silicon substrate after the step iii) is completed.

Zinc oxide nanowires (nanowire) according to the present invention is a zinc oxide nanocrystals in the form of a wire having a direction around one axis, the oxidation of the present invention any nanowires or nanowires commonly used in the art Zinc nanowires.

Here, the zinc oxide nanowires may be manufactured at a specific position of the silicon substrate, that is, at a selected position. In the present invention, the zinc oxide nanowires manufactured at the selected position will be referred to as specifically selective zinc oxide nanowires. do.

The zinc oxide seed according to the present invention is applied on a silicon substrate so that the zinc oxide nanowires are grown in a selective direction from the seed, and the thickness thereof may be adjusted according to the diameter and length of the nanowire to be manufactured. have.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. However, the following description is only for describing the present invention in detail and does not limit the scope of the present invention by the following description.

1 is described together with a process diagram showing a method for producing a zinc oxide nanowire according to the present invention.

As shown in FIG. 1, the method for manufacturing the zinc oxide nanowires, and specifically the selective zinc oxide nanowires 14 according to the present invention is as follows.

First) forming an aluminum layer 4 on the silicon substrate 2;

Ii) a patterning step of forming and then patterning a photoresist layer 6 on top of the aluminum layer 4 of step iii);

Iv) anodizing to anodize the aluminum layer 4 to form a porous aluminum oxide layer 8 after the patterning step of step ii) is finished;

Iii) the step iii) forming a zinc oxide seed layer 12 by applying a zinc oxide seed on the silicon substrate 2 on which the porous aluminum oxide layer 8 is formed;

Iii) sequentially removing the photoresist layer 6 and the porous aluminum oxide layer 12 after the step iii) is finished; And

Iii) a zinc oxide growth step of growing the zinc oxide seed applied to the silicon substrate 2 after the step iii) is completed.

Here, the anodizing step of forming the porous aluminum oxide layer 8 of step iii) forms a pore 10 in the aluminum layer 4, so that the zinc oxide seed is deposited on the bottom of the pore 10 of the aluminum oxide layer 8. That is, to be applied to the surface of the silicon substrate (2), any of the conventional anodization methods in the art used for this purpose may be used, but preferably includes an aluminum layer (4) in the anode An electrolytic solution consisting of 0.5 to 10% by weight of oxalic acid and 90 to 99.5% by weight of a solvent, which is installed at a silicon substrate 2 and a Pb plate is installed at the cathode, and maintained at 0 to 30 ° C, preferably 10 to 20 ° C. A primary anodizing step of oxidizing the aluminum layer 4 for 50 to 70 minutes, preferably about 60 minutes, at a voltage of 30 to 50V at; The silicon substrate 2 including the aluminum layer 4 having the first anodization step completed is 4 to 8% by weight of phosphoric acid, 1 to 2.5% by weight of chromic acid, and 89.5 to 8, maintained at a temperature of 60 to 70 ° C. Immersing in a phosphate-chromic acid mixed solution composed of 97.5% by weight of a solvent to remove aluminum oxide according to primary anodization, that is, alumina; And the silicon substrate 2 including the aluminum layer 8 having the above-mentioned steps immersed in an aqueous solution of phosphoric acid composed of 4 to 8% by weight of phosphoric acid and 92 to 96% by weight of a solvent maintained at 20 to 40 ° C. 10 may be enlarged.

At this time, the size of the plurality of pores 10 formed in the porous aluminum oxide layer 8 is preferably formed in each of 200 to 500nm, the solvent used is not particularly limited as a solvent commonly used in the art, but preferably For example, it is preferable to use water, particularly ultrapure water having a resistance of 17 to 18 MΩ / cm ² .

The application of zinc oxide seeds on the silicon substrate on which the porous aluminum oxide layer 8 of step iii) is formed to form the zinc oxide seed layer 12 is conventional in the art of applying zinc oxide seeds onto a silicon substrate. Any method may be used as long as it is a phosphorus method, for example, a zinc oxide RF sputtering method, a method of immersing in a solution containing zinc oxide, or a method of vapor deposition of zinc particles.

On the other hand, removing the photoresist layer 6 of step iii) according to the present invention is a photoresist removal method commonly used in the art, for example, a photo using SPM (sulfuric acid hydrogenperoxide mixture) or piranha Any method of removing the resist may be used, but it is preferable to use a method of oxidizing and dissolving the photoresist by oxidizing ozone dissolved in an aqueous solution using ozone, which is a powerful oxidizing agent.

In addition, removing the porous aluminum oxide layer 8 of step iii) is not particularly limited as long as it is a porous aluminum oxide removing method commonly used in the art, but is preferably maintained at a temperature of 60 to 70 ° C. It is preferable to use a method of immersion in a phosphoric acid-chromic acid mixed solution consisting of from 8% by weight of phosphoric acid, 1 to 2.5% by weight of chromic acid and 89.5 to 97.5% by weight of a solvent.

At this time, the solvent to be used is not particularly limited as a solvent commonly used in the art, but it is preferable to use water, particularly ultrapure water having a resistance of 17 to 18 MΩ / cm ² .

The zinc oxide growth step of step iii) according to the present invention may be used as long as it is a zinc oxide growth method commonly used in the art, but it is recommended to use a solution method.

Specifically describing the solution method as a method of growing a zinc oxide seed according to the present invention, a silicon substrate on which a zinc oxide seed is applied to form a zinc oxide seed layer 12 is 30 to 100 ° C., preferably 50 to It consists of immersion in an aqueous solution comprising zinc salt, hydroxide and ammonium groups maintained at pH 10-12 having a temperature of 70 ° C., particularly preferably about 60 ° C., for 5-7 hours, preferably about 6 hours.

At this time, the aqueous solution containing the zinc salt, hydroxyl group and ammonium group is 0.8 to 1% by weight of zinc nitrate and 1 to 6% by weight of ammonium hydroxide mixture based on the total weight of the aqueous solution; Or 1-3 wt% zinc sulfate, 1-3 wt% ammonium chloride and 2-10 wt% sodium hydroxide mixture; Or from 6 to 8% by weight of zinc acetate, from 6 to 12% by weight of ethylenediamine and from 1 to 7% by weight of sodium hydroxide, the solvent used being water, preferably resisting 17 to 18 MΩ / cm ^2. It is better to use ultrapure water.

The particularly preferred pH of the aqueous solution comprising the zinc nitrate and ammonium hydroxide mixture is about 10.3, the particularly preferred pH of the aqueous solution comprising zinc sulfate, ammonium chloride and sodium hydroxide mixture is about 10.6, zinc acetate, ethylenediamine And particularly preferred pH of the aqueous solution comprising a sodium hydroxide mixture is about 12.0.

In particular, in the production of zinc oxide nanowires according to the present invention, the pH range in which the diameter and length of the zinc oxide nanowires produced according to the temperature is limited is limited, in the production temperature range of the zinc oxide nanowires according to the present invention Zinc oxide nanowire growth is optimized with each mixture pH mentioned.

In addition, in the production of zinc oxide nanowires through zinc oxide growth according to the present invention, the solution method is that the zinc oxide nanowires prepared according to the thickness of the zinc oxide seed layer 12 in addition to the pH and temperature, the diameter and length As can be controlled, as the thickness of the zinc oxide seed layer 12 formed on the silicon substrate 2 increases, the length of the zinc oxide nanowires decreases and the diameter increases together.

In particular, when the thickness of the zinc oxide seed layer 12 formed on the silicon substrate 2 is 300 nm or less, the length of the zinc oxide nanowires produced according to the thickness of the seed layer is shortened linearly, and the zinc oxide seed layer 12 When the thickness of the?) Is 300 nm or more, the length of the zinc oxide nanowires produced is almost constant, and the diameter increases logarithmically.

However, when the thickness of the zinc oxide seed layer 12 is 5 nm or less, no zinc oxide nanowires are formed.

Therefore, in the method for producing a zinc oxide nanowire according to the present invention, the thickness of the zinc oxide seed layer 12 formed on the silicon substrate 2 should be at least 5 nm or more, preferably around 300 nm, particularly preferably 100 It is good to be 1000 nm.

As described above, those skilled in the art will understand that the present invention can be implemented in other specific forms without changing the technical spirit or essential features. Therefore, the exemplary embodiments described above are to be understood as illustrative in all respects and not as restrictive. The scope of the present invention should be construed that all changes or modifications derived from the meaning and scope of the appended claims and their equivalents, rather than the detailed description, are included in the scope of the present invention.

The present invention uses a layer of aluminum and a photoresist layer formed on a silicon substrate to produce zinc oxide nanowires in a selected region in an atmosphere similar to room temperature and pressure, whereby homogeneous zinc oxide nanowires are well aligned in a few processes. There is an effect that can be prepared.

Claims (8)

Iii) forming an aluminum layer on the silicon substrate; Ii) a patterning step of forming and then patterning a photoresist layer on top of the aluminum layer of step iii); Iv) anodizing to form a porous aluminum oxide layer by anodizing the aluminum layer after the patterning step of step ii) is finished; Iii) applying zinc oxide seeds on the silicon substrate on which the porous aluminum oxide layer of step iv) is formed to form a zinc oxide seed layer; Iii) sequentially removing the photoresist layer and the porous aluminum oxide layer after step iii) is finished; And Iv) a zinc salt and a hydroxyl group in which a zinc oxide seed-coated silicon substrate is maintained at a pH of 10 to 12 having a temperature of 30 to 100 ° C. in order to grow the zinc oxide seed coated on the silicon substrate after the step iii) is completed. And a zinc oxide growth step of immersing for 5 to 7 hours in an aqueous solution containing an ammonium group. The method of claim 1, The thickness of the zinc oxide seed layer of step iii) is 100 to 1000nm, characterized in that the manufacturing method of zinc oxide nanowires. The method of claim 1, Anodizing to form a porous aluminum oxide layer of step iii) The first anodization step of oxidizing the aluminum layer for 50 to 70 minutes at a voltage of 30 to 50V in an electrolyte solution of 10 to 30 ℃ after installing aluminum on the anode of the silicon substrate including the aluminum layer and Pb plate on the cathode ; The silicon substrate including the aluminum layer of the first anodization step is completed with 4 to 8% by weight of phosphoric acid, 1 to 2.5% by weight of chromic acid and 89.5 to 97.5% by weight of solvent maintained at a temperature of 60 to 70 ℃ A secondary anodization step of removing aluminum oxide by immersing in the phosphate-chromic acid mixture solution; And The silicon substrate including the aluminum layer after the second anodization step is immersed in an aqueous solution of phosphoric acid consisting of 4 to 8% by weight of phosphoric acid and 92 to 96% by weight of a solvent maintained at 20 to 40 ℃ to enlarge the pores Method for producing zinc oxide nanowires, characterized in that consisting of steps. The method of claim 3, wherein The electrolyte solution is a method for producing zinc oxide nanowires, characterized in that consisting of 0.5 to 10% by weight of oxalic acid and 90 to 99.5% by weight of the solvent. The method of claim 1, Removing the photoresist layer of step (iii) by oxidizing and dissolving the photoresist using ozone water in which ozone is dissolved in water.  The method of claim 1, Removing the porous aluminum oxide layer of step iii) consists of 4-8 wt% phosphoric acid, 1-2.5 wt% chromic acid and 89.5-97.5 wt% solvent, maintained at a temperature of 60-70 ° C. Method for producing zinc oxide nanowires comprising immersing in a mixed solution. delete The method of claim 1, The aqueous solution containing the zinc salt, hydroxyl group and ammonium group is 0.8 to 1% by weight of zinc nitrate and 1 to 6% by weight of ammonium hydroxide mixture based on the total weight of the aqueous solution; Or 1-3 wt% zinc sulfate, 1-3 wt% ammonium chloride and 2-10 wt% sodium hydroxide mixture; Or 6 to 8% by weight of zinc acetate, 6 to 12% by weight of ethylenediamine and 1 to 7% by weight of sodium hydroxide mixture.

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