KR101772694B1

KR101772694B1 - Method for fabricating nanostructure and method for fabricating electronic devices using the same

Info

Publication number: KR101772694B1
Application number: KR1020100101901A
Authority: KR
Inventors: 박원일; 이재석
Original assignee: 한양대학교 산학협력단
Priority date: 2010-10-19
Filing date: 2010-10-19
Publication date: 2017-08-29
Also published as: KR20120040462A

Abstract

A method of manufacturing a nanostructure and a method of manufacturing an electronic device using the same are provided. A method of fabricating a nanostructure includes: forming a micro concavo-convex structure by etching a surface of a substrate; depositing a metal catalyst on the substrate having the microstructure formed thereon; and depositing a vapor-liquid-solid- ) Method to form a nanocone. A method of manufacturing an electronic device includes the steps of forming a pn junction semiconductor layer in which a p-type semiconductor layer and an n-type semiconductor layer are bonded to each other, etching the surface of at least one of the p- Depositing a metal catalyst on the semiconductor layer on which the micro concavo-convex structure is formed; and forming a nanocon on the semiconductor layer on which the metal catalyst is deposited by using a vapor-liquid-solid-phase (VLS) method . According to the present invention, it is possible to easily form nano-cones by forming a micro concavo-convex structure on the surface of a substrate, and it is possible to form a nanostructure having a desired shape at a desired position on one substrate by grafting with a lithography method. In addition, there is an effect that the light absorption efficiency of the solar cell and the light extraction efficiency of the light emitting diode can be improved by manufacturing the electronic device using the nanocone manufacturing method of the present invention.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of fabricating a nanostructure and a method of fabricating the same,

The present invention relates to a method of manufacturing a nanostructure, and more particularly, to a method of manufacturing a nanostructure and a method of manufacturing an electronic device using the same.

Nanostructured materials exhibit unique electrical, magnetic, and optical properties due to size effects and quantum confinement effects, and many studies have been conducted to apply them to semiconductor devices. In particular, a 1-dimensional nanostructure has a wide specific surface area and a large aspect ratio, and is a structure suitable for use in transistors, sensors, solar cells, and light emitting diodes. However, unlike nanowires among 1-dimensional nanostructures, the research on nanoconses is relatively small, and the conventional method of forming nanocons includes the experimental factors such as the type, amount, and temperature of the reactant gas in the condition of growing the nanowires Or nanowires grown on the surface of the nanotubes were etched and converted into nanocon shapes. In this case, it is not easy to control the shape of the nanostructure to be grown, and the nanostructures formed on one substrate are forced to have the same shape at one time, which is not suitable for application to various devices. Accordingly, there is a need for a new manufacturing technique for arranging and shaping nanostructured materials suitable for the functions required in the device.

SUMMARY OF THE INVENTION The present invention provides a method of fabricating a nanostructure including a nanocon by a simple method.

It is another object of the present invention to provide a method of manufacturing an electronic device having improved efficiency by using the method of manufacturing the nanostructure.

According to an aspect of the present invention, there is provided a method of fabricating a nanostructure. The method includes: forming a micro concavo-convex structure by etching a surface of a substrate; depositing a metal catalyst on the substrate having the micro concavo-convex structure; and applying a gas-liquid-solid (VLS) To form a nanocon.

The substrate may be any one selected from the group consisting of a silicon substrate, a silicon carbide substrate, a quartz substrate, a Group 13-15 compound semiconductor substrate, a Group 12-16 compound semiconductor substrate, and a sapphire substrate.

The step of forming the micro concavo-convex structure may be performed by wet etching using an acid solution, dry etching using plasma, or etching using a nanoindenter.

The metal catalyst may be selected from among gold, silver, aluminum, copper, nickel, palladium, platinum, ruthenium, cobalt, gallium and two or more alloys thereof.

The nanocone may comprise a material selected from the group consisting of Group 12 elements, Group 13 elements, Group 14 elements, Group 15 elements, Group 16 elements, and alloys of two or more elements belonging to different families of the elements.

According to another aspect of the present invention, there is provided a method of fabricating a nanostructure, comprising: forming a protective layer on a surface of the substrate to etch the substrate before etching the surface of the substrate; After forming the micro concavo-convex structure, removing the protective layer.

The protective layer may be a polymer film, and the step of forming the protective layer may be performed by a photolithography method, an electron beam lithography method, or a nanoimprint lithography method.

According to another aspect of the present invention, there is provided a method of manufacturing an electronic device. The method includes forming a pn junction semiconductor layer in which a p-type semiconductor layer and an n-type semiconductor layer are bonded to each other, etching a surface of at least one of the p-type semiconductor layer and the n- Depositing a metal catalyst on the semiconductor layer on which the micro concavo-convex structure is formed; and forming a nanocon using a vapor-liquid-solid-phase (VLS) method on the semiconductor layer on which the metal catalyst is deposited .

The electronic device may be a solar cell or a light emitting diode.

As described above, according to the present invention, the nanocon cone can be easily formed by forming the micro concavo-convex structure on the surface of the substrate. In addition, there is an advantage that nanostructures (nanowires and nanocon) having a desired shape can be formed at a desired position on one substrate by combining with a lithography method. In addition, there is an effect that the light absorption efficiency of the solar cell and the light extraction efficiency of the light emitting diode can be improved by manufacturing the electronic device using the nanocone manufacturing method of the present invention.

However, the effects of the present invention are not limited to the above-mentioned effects, and other effects not mentioned can be clearly understood by those skilled in the art from the following description.

1A to 1C are perspective views illustrating a method of fabricating a nanostructure according to an embodiment of the present invention.
2 is a schematic illustration of a nanocon formation mechanism according to an embodiment of the present invention.
3A to 3E are perspective views illustrating a method of fabricating a nanostructure according to another embodiment of the present invention.
4A to 4D are sectional views showing an embodiment of a method of manufacturing an electronic device using the method of manufacturing a nanostructure of the present invention.
Figures 5 and 6 are SEM images and AFM images, respectively, showing the surface of a substrate etched with microstructures.
7 is an SEM image of the nanostructure produced according to Preparation Example 1. FIG.
8 is a photograph of a silicon substrate (a) on which a nanocon is not formed and a silicon substrate (b) on which a nanocon is formed under a fluorescent lamp.
9 is a graph showing the reflectance and the simulation result according to the presence or absence of the nanocone.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Rather, the embodiments disclosed herein are provided so that the disclosure can be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the thicknesses of layers and regions are exaggerated or reduced for clarity. Like reference numerals designate like elements throughout the specification. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

1A to 1C are perspective views illustrating a method of fabricating a nanostructure according to an embodiment of the present invention.

Referring to FIG. 1A, the surface of the prepared substrate 100 is etched to form a micro concavo-convex structure 110.

The substrate 100 can be selected from a silicon substrate, a silicon carbide substrate, a quartz substrate, a Group 13-15 compound semiconductor substrate, a Group 12-16 compound semiconductor substrate, and a sapphire substrate. However, the present invention is not limited thereto, and any substrate capable of epitaxy growth of a material for forming a nano-cone described later can be used without limitation. It should also be understood that the term " substrate " as used herein is intended to encompass all types of bases that are the basis for the growth of the nanostructure of interest herein.

The etching of the surface of the substrate 100 may be performed by various known methods. For example, wet etching using an acid solution as an etching solution, dry etching using plasma, or etching using a nanoindenter. The fine concavo-convex structure 110 can be formed by removing a part of the surface of the substrate 100 by this etching process (the solid line of the surface of the substrate 100 shown in Fig. 1A represents the etched portion). The concave-convex structure 110 to be formed may be regular or irregular depending on the etching method. At this time, it is preferable that the size (including the height and width of the concavities and convexities) of the concavo-convex structure 110 is formed at a nanoscale of 1 to 100 nm. Accordingly, the surface area of the substrate 100 can be increased to have a high surface energy, and the reactivity with the reactive gas supplied in the gas-liquid-solid-solid method, which will be described later, can be increased.

Before the etching of the surface of the substrate 100, the substrate is washed with an organic solvent such as acetone and alcohol, deionized water or the like as necessary in order to remove impurities on the substrate surface, and dried using nitrogen gas have.

Referring to FIG. 1B, a metal catalyst 120 is deposited on a substrate 100 having the micro concavo-convex structure 110 formed thereon.

The metal catalyst 120 may be any one selected from gold, silver, aluminum, copper, nickel, palladium, platinum, ruthenium, cobalt, gallium and alloys of two or more thereof. However, the present invention is not limited thereto, and any kind of metal catalyst that can be used to form a nanostructure using a vapor-liquid-solid (VLS) method can be used. The metal catalyst 120 may be deposited on the substrate 100 by known chemical, physical, or any combination thereof, such as sputtering, ion beam deposition, chemical vapor deposition, and plasma deposition. Preferably, the substrate 100 on which the micro concavo-convex structure 110 is formed is immersed in a gold colloid solution to deposit the metal catalyst 120.

Referring to FIG. 1C, the nanocone 130 is formed on the substrate 100 on which the metal catalyst 120 is deposited, using a vapor-liquid-solid method.

The nanocone 130 may include a material selected from the group consisting of a Group 12 element, a Group 13 element, a Group 14 element, a Group 15 element, a Group 16 element, and an alloy of two or more elements belonging to different groups. For example, the material may be selected from the group consisting of Si, Ge, Ga, As, P, B, Zn, Se, S, Cd, Sn, Al, In, SiGe, GaN, GaP, GaAs, AlGaAs, GaAsP, InN, It may be selected from InGaAs, AlN, AlAs, InP, GaP, ZnO, ZnSe, CdS, ZnCdS, CdSe, CuSe, CuInSe ₂ and combinations thereof. At this time, it is preferable that the nanocone 130 is selected as a material capable of epitaxy growth on the substrate 100. In the vapor-liquid-solid-phase method, the material forming the nanocone 130 is injected in the form of a reaction gas containing the material (precursor gas for forming a nanocone) And then precipitated as a solid material to form a nanocone. For example, silane (SiH ₄ ) gas can be used as a reaction gas when Si nano cone is formed, and trimethyl gallium ((CH ₃ ) ₃ Ga) gas And ammonia (NH ₃ ) gas can be used at the same time.

2 is a schematic illustration of a nanocon formation mechanism according to an embodiment of the present invention.

As described above, when the substrate 100 on which a metal catalyst is deposited is mounted on a reactor (furnace) and the reaction gas is injected at a temperature of a certain temperature (for example, 650 ° C or higher) When the reaction gas is mixed at a solubility limit above the solubility limit, an element contained in the reaction gas is precipitated in a solid phase to form a nano structure (nano structure) grown on the substrate 100 Wire).

On the other hand, with this vertical growth (v), the substrate 100 having the fine concavo-convex structure 110 on its surface can increase the contact area and reactivity with the reaction gas 200 flowing along the surface by the increased surface area . Accordingly, vapor epitaxy (VPE) growth can be promoted on the surface of the substrate 100, and horizontal growth (h) can be caused on the side of the nanostructure grown vertically (v). Accordingly, both the vertical growth (v) and the horizontal growth (h) occur in the growth process of the nanostructure, and as a result, it is determined that the nanostructure 130 of the nanocon conformation is finally formed.

3A to 3E are perspective views illustrating a method of fabricating a nanostructure according to another embodiment of the present invention.

Referring to FIG. 3A, a protective layer 105 is formed on a part of a surface of a substrate 100. The protective layer 105 is a layer for preventing etching of the surface of the substrate 100, and may be, for example, a polymer film. However, the present invention is not limited thereto, and any material can be used as long as it can prevent etching of the surface of the substrate 100, and can easily remove the substrate 100 from the substrate 100 without damaging the substrate 100.

The formation of the protective layer 105 can be performed by a known lithography method such as photolithography, electron beam lithography, or nanoimprint lithography. For example, in the case of using the photolithography method, the photosensitive polymer is coated on the substrate 100 by spin coating or the like to form a photoresist film, exposed using a patterned mask, and developed to form a photoresist pattern . At this time, the patterned photoresist film serves as the protective layer 105.

Referring to FIG. 3B, the surface of the substrate 100 on which the protective layer 105 is formed is etched to form the micro concavo-convex structure 110. This process is the same as that described above with reference to FIG. 1A.

Referring to FIG. 3C, the protective layer 105 is removed from the substrate 100 on which the etching process has been performed. The removal of the protective layer 105 can be appropriately selected depending on the material constituting the protective layer 105. If the protective layer 105 is a polymer membrane, it can be removed using an organic solvent such as acetone.

Referring to FIG. 3D, a metal catalyst 120 is deposited on a substrate 100 having a micro concavo-convex structure 110 formed on a surface thereof. This process is the same as that described above with reference to FIG. 1B.

Referring to FIG. 3E, nanostructures 125 and 130 are formed on a substrate 100 on which a metal catalyst 120 is deposited, using a vapor-liquid-solid method. In this process, the nanowire 125 is formed on the surface of the substrate 100 where the micro concavo-convex structure 110 is not formed, and the nanocon 130 is formed on the portion where the micro concavo-convex structure 110 is formed. The formation mechanism of the nanowires 125 and the nanocones 130 is the same as that described in FIG.

As described above, according to this embodiment, by combining the lithography-based patterning technique and the process of forming the micro concavo-convex structure 110 on the surface of the substrate 100, nanostructures of desired shapes (nanowires and nanocon) There is an advantage that it can grow easily.

In the present embodiment, a method of fabricating a nanostructure (nanowire and nanocon) including a process of forming and removing the protective layer 105 has been proposed. However, a method of forming a micro concavo-convex structure on the surface of the substrate 100, In the case of using an indenter, nanowires and nano-cones may be respectively formed at desired positions on one substrate 100 without forming and removing the protective layer 105. That is, in the case of using the nanoindenter, it is possible to form a concavo-convex structure by pushing a sharp indenter into the substrate 100 and forming a nano-scale scratch on a part of the surface of the substrate 100 It is because.

4A to 4D are sectional views showing an embodiment of a method of manufacturing an electronic device using the method of manufacturing a nanostructure of the present invention.

4A, a pn junction semiconductor layer 400 is formed in which a p-type semiconductor layer 400a or 400b and an n-type semiconductor layer 400b or 400a are bonded to each other. Herein, a p-type semiconductor, and the other is an n-type semiconductor). The p-type semiconductor layer and the n-type semiconductor layer include a material selected from the group consisting of Group 12 elements, Group 13 elements, Group 14 elements, Group 15 elements, Group 16 elements, and alloys of two or more elements belonging to different groups And may be formed into a desired type of semiconductor layer by selectively doping with a suitable dopant. For example, the material may be selected from the group consisting of Si, Ge, Ga, As, P, B, Zn, Se, S, Cd, Sn, Al, In, SiGe, GaN, GaP, GaAs, AlGaAs, GaAsP, InN, It may be selected from InGaAs, AlN, AlAs, InP, GaP, ZnO, ZnSe, CdS, ZnCdS, CdSe, CuSe, CuInSe ₂ and combinations thereof.

The pn junction semiconductor layer 400 can be formed by a known method. For example, in the case of a pn junction silicon layer, an n-type dopant is formed by ion doping the p-type silicon layer 400a using a high temperature diffusion method . For example, the p-type compound semiconductor layer may be formed on the n-type compound semiconductor layer 400a by a co-evaporation method, a sputtering method, an electrodeposition method, a chemical vapor deposition method, 400b may be stacked. However, the present invention is not limited thereto.

Referring to FIG. 4B, the surface (at 400b in this embodiment) of at least one of the p-type semiconductor layer and the n-type semiconductor layer of the substrate is etched to form the micro concavo-convex structure 410. FIG. The formation of the fine uneven structure 410 is the same as that described above with reference to FIG.

4C and 4D, after the metal catalyst 420 is deposited on the semiconductor layer 400b on which the micro concavo-convex structure 410 is formed, the metal catalyst 420 is deposited on the semiconductor layer 400b on which the metal catalyst 420 is deposited. A liquid-phase (VLS) method is used to form the nanocone 430. The deposition of the metal catalyst 420 and the formation of the nanocone 430 are the same as those described in FIGS. 1B and 1C, respectively.

The electronic device may be formed as a solar cell or a light emitting diode by forming electrodes on the front and back surfaces of the p-n junction semiconductor layer 400 on which the nanocone 430 is formed by using a conductive material. Although the process of forming the nano-cone 430 on the pn junction semiconductor layer 400 and then forming the electrode is described as an example, the pn junction semiconductor layer 400 may be formed by depositing a rear electrode It will be apparent to those skilled in the art that a front electrode may be formed after formation of the nanocone 430 to form an electronic device.

The solar cell manufactured according to the present embodiment can improve the light absorption efficiency since the nanocone 430 array vertically aligned on the pn junction semiconductor layer 400 can serve as the antireflection film. In addition, the light emitting diode manufactured according to the present embodiment can improve the light extraction efficiency because the surface texturing effect can be obtained due to the nanocone 430 array vertically aligned on the pn junction semiconductor layer 400.

Hereinafter, exemplary embodiments of the present invention will be described in order to facilitate understanding of the present invention. It should be understood, however, that the following examples are intended to aid in the understanding of the present invention and are not intended to limit the scope of the present invention.

&Lt; Preparation Example 1 &

A. Formation of fine concave-convex structure on substrate surface

The single crystal silicon substrate was ultrasonicated with acetone and ethanol, washed with deionized water, and the washed substrate was dried with N ₂ gas. Next, to remove the natural oxide film (silicon oxide) layer of the silicon substrate, the substrate was immersed in the HF aqueous solution for about 30 seconds, and then washed with distilled water to remove HF remaining on the substrate.

A photoresist (AZ1512, Clariant) was spin-coated on the pretreated silicon substrate at 500 rpm for 3 seconds and at 3000 rpm for 35 seconds, and the film was cured by heating on a hot plate at 100 DEG C for 1 minute. A portion of the substrate on which the photoresist was deposited was covered with a mask and photodetected, and then the photoresist portion was removed by putting it in a developer (CPD-18).

The patterned substrate was immersed in a mixed solution of HF and TFG (Transene) (HF: THF: H ₂ O volume ratio = 1: 1: 8) for about 5 minutes so that the surface of the substrate on which the photoresist was not deposited was etched into the microstructure. At this time, the formed microstructure showed an irregular concave-convex structure. Subsequently, the photoresist remaining on the substrate was removed with acetone.

Figures 5 and 6 are SEM images and AFM images (including line profiles) showing the surface of the substrate etched into the microstructures, respectively.

Referring to FIGS. 5 and 6, irregular concavo-convex structures having a width of about 20-30 nm and a height of about 1-2 nm are produced.

B. Preparation of nanostructures

The substrate on which the photoresist was removed was immersed again in the HF aqueous solution to remove the natural oxide film and then immersed in the gold colloid solution for at least 30 minutes to deposit gold on the substrate surface. The substrate on which the gold was deposited was placed in a furnace and the pump was operated to adjust the pressure to 10 ^-3 torr or less. Thereafter, the temperature of the furnace was raised to 650 to 750 ° C at room temperature and maintained. Then, SiH ₄ and H ₂ were injected at a rate of 1 sccm and 10-30 sccm, respectively, and the pressure was adjusted to 10 Torr to grow the nanostructure on the substrate surface for 5 minutes to 2 hours.

7 is an SEM image of the nanostructure produced according to Preparation Example 1. FIG. Here, (a) represents a nanostructure grown on a substrate on which a micro concavo-convex structure is not formed, and (b) represents a nanostructure grown on a substrate on which a micro concavo-convex structure is formed.

Referring to FIG. 7, it can be seen that the nanostructures grown on the substrate having the micro concavo-convex structure have the shape of nanocon.

&Lt; Measurement of antireflection effect >

The anti-reflection effect of the substrate due to the formation of the nanocon was measured.

8 is a photograph of a silicon substrate (a) on which a nanocon is not formed and a silicon substrate (b) on which a nanocon is formed under a fluorescent lamp.

9 is a graph showing the reflectance and the simulation result according to the presence or absence of the nanocone. FIGS. 9A and 9B are actual reflectance and simulation results of a silicon substrate on which a nanocon is not formed, and FIGS. 9C and 9D are actual reflectance and simulation results of a silicon substrate on which a nanocon is formed, respectively .

Referring to FIGS. 8 and 9, it can be seen that the substrate on which a nanocone is formed has a higher anti-reflection effect than a substrate on which a nanocone is not formed.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the present invention is not limited to the disclosed exemplary embodiments, and various changes and modifications may be made by those skilled in the art without departing from the scope and spirit of the invention. Change is possible.

100: substrate 105: protective layer
110, 410: fine concave-convex structure 120, 420: metal catalyst
125: nanowire 130, 430: nanocon
200: reaction gas 400: pn junction semiconductor layer

Claims

Forming a fine concavo-convex structure by etching the substrate surface;
Exposing the micro concavo-convex structure between the metal catalysts by forming a metal catalyst on the substrate having the micro concavo-convex structure formed thereon; And
Forming a nanocon by using a gas-liquid-solid-phase (VLS) method by exposing a reaction gas on the substrate,
Wherein the reaction gas reacts with the metal catalyst to form a nanostructure and the reaction gas induces horizontal growth of the nanostructure while flowing along the exposed micro concavo-convex structure to form the nanoconstructure. Gt;

The method according to claim 1,
Wherein the substrate is selected from the group consisting of a silicon substrate, a silicon carbide substrate, a quartz substrate, a Group 13-15 compound semiconductor substrate, a Group 12-16 compound semiconductor substrate, and a sapphire substrate.

The method according to claim 1,
Wherein the step of forming the micro concavo-convex structure is performed by wet etching using an acid solution, dry etching using plasma, or etching using a nanoindenter.

The method according to claim 1,
Wherein the metal catalyst is selected from gold, silver, aluminum, copper, nickel, palladium, platinum, ruthenium, cobalt, gallium and two or more alloys thereof.

The method according to claim 1,
Wherein the nanocone comprises a material selected from the group consisting of Group 12 elements, Group 13 elements, Group 14 elements, Group 15 elements, Group 16 elements, and alloys of two or more elements belonging to different families.

The method according to claim 1,
Forming a protective layer on an area of the substrate surface to prevent etching before etching the substrate surface; And
Forming a micro concavo-convex structure by etching the surface of the substrate on which the protective layer is not formed, and then removing the protective layer.

The method according to claim 6,
Wherein the protective layer is a polymer membrane.

The method according to claim 6,
Wherein the step of forming the protective layer is performed by a photolithography method, an electron beam lithography method, or a nanoimprint lithography method.

forming a pn junction semiconductor layer in which a p-type semiconductor layer and an n-type semiconductor layer are bonded;
Etching the surface of at least one of the p-type semiconductor layer and the n-type semiconductor layer to form a micro concavo-convex structure;
Exposing the micro concavo-convex structure between the metal catalysts by forming a metal catalyst on the semiconductor layer having the micro concavo-convex structure; And
Forming a nanocrystal by exposing a reaction gas on the semiconductor layer using a vapor-liquid-solid-phase (VLS) method,
Wherein the reaction gas reacts with the metal catalyst to form a nanostructure and the reaction gas induces horizontal growth of the nanostructure while flowing along the exposed micro concavo-convex structure to form the nanoconstructure. Gt;

10. The method of claim 9,
Wherein the electronic device is a solar cell or a light emitting diode.