WO2014157991A1

WO2014157991A1 - Method for manufacturing air-suspended single carbon nanowire and overlapping nanoelectrode pair

Info

Publication number: WO2014157991A1
Application number: PCT/KR2014/002670
Authority: WO
Inventors: 신흥주; 허정일; 임영진
Original assignee: 에스케이이노베이션 주식회사; 국립대학법인 울산과학기술대학교 산학협력단
Priority date: 2013-03-29
Filing date: 2014-03-28
Publication date: 2014-10-02

Abstract

The present invention provides a method for manufacturing an air-suspended single carbon nanowire and an overlapping nanoelectrode pair, and an air-suspended single carbon nanowire and an overlapping nanoelectrode pair manufactured using said method. An air-suspended single carbon nanowire, which is manufactured at a high yield ratio by the method for manufacturing an air-suspended single carbon nanowire according to the present invention, has a minimized size, and an air-suspended carbon nanomesh, which is manufactured at a high yield ratio by the method for manufacturing an overlapping nanoelectrode pair according to the present invention, is thin and dense. The present invention also provides a gas sensor or an electrochemical sensor, to which an air-suspended single carbon nanowire and an overlapping nanoelectrode pair manufactured by the method according to the present invention are applied.

Description

[Specification]

[Name of invention]

Manufacturing method of airborne single carbon nanowire and superposed nano electrode pair

The present invention relates to a method of preparing a floating-type single carbon nanowire and a superposed nano-electrode pair, and a floating-type single carbon nanowire and a superposed nano-electrode pair prepared through the preparation method thereof. More specifically, a method for preparing a notary float type single carbon nanowire for minimizing the size of an airborne type single carbon nanowire, and a method for manufacturing a superposed type nanoelectrode pair for forming a thin and dense notched float type carbon nanomesh. It is about. The present invention also relates to a gas sensor or an electrochemical sensor using the airborne type single carbon nanowires and superposed nano-electrode pairs produced through the manufacturing method of the present invention.

Background technology

In recent years, with increasing interest in environmental problems and the development of information and communication devices, sensors for various gases are being developed, incorporating semiconductor technology has made manufacturing easier and improved its performance. For all sensors, the highest goal is to increase the sensitivity to improve performance, and efforts to achieve this goal are increasing. On the other hand, the conventional semiconductor gas sensor has a limitation on the sensitivity because the sensing material is a semiconductor thin film, for example, it was almost impossible to detect a stable chemical such as carbon dioxide (C0 ₂ ).

Therefore, sensors for detecting harmful gases such as carbon monoxide (CO) and carbon dioxide can be used for the electrochemical method using the solution method of solution, the optical method by infrared absorption method, and the method of measuring the electrical resistance of nanoparticles or nanowires. This is being applied.

The electrochemical method is to measure the current flowing through the external circuit by electrochemically oxidizing or reducing the target gas, or by using an electromotive force generated by the action of ions in the gas phase dissolved or ionized in an electrolyte solution or solid, In addition to showing a very slow reaction speed, gas detection range and use environment are limited, and the price is expensive.

In addition, the optical method by the infrared absorption method has the advantage that it is almost unaffected by other mixed gases or humidity, but the device is not only complicated and large size. The price is also expensive.

In general, a chemical sensor has a structure for detecting gas by contact combustion method, and when the gas is reacted with a sensor including a platinum wire as a catalyst, it uses a resistance change of the platinum wire due to an exothermic reaction or an endothermic reaction. It is able to detect gas, improving the stability and sensitivity of the sensor.

On the other hand, as the relationship between the contact reaction and the electron density caused by the chemical adsorption of gas has been recently developed, an oxide semiconductor gas sensor has been developed and commercialized. Such a semiconductor gas sensor detects most gases including flammable gas. It has been developed to make it possible to achieve smaller size, lower cost, and improved reliability than other gas sensors.

Gas sensors using carbon nanotubes applied as such semiconductor gas sensors had to be heated up to about 30C C to detect nitrogen oxides. However, carbon nanotubes can operate at room temperature. Since the particle size is nanoscale, the sensor's sensitivity is several thousand times higher than that of other sensors.

Gas sensors have been developed that measure the change in electrical resistance of nanoparticles themselves or nanoparticle-coated materials depending on the concentration of the measurement gas. The use of nanoparticles makes the sensor highly sensitive because the volume-to-area ratio is very high, and the effect of the surface reaction with the change of gas concentration is very large.

In general, sensors using nanoparticles or nanowires disperse these materials irregularly on the surface, connecting electrodes that can measure the change in electrical resistance of these nanomaterials only in specific areas, or by blowing nanomaterials onto pre-patterned electrodes. Alternatively, the electrical resistance was measured by contacting the electrode using an electrospinning method. This method has the disadvantage that the physical and electrical connection between the nanomaterial and the electrode is unstable and the nanomaterial in contact with the surface is affected by the surface during gas sensing.

Subsequently, as disclosed in Non-Patent Document 1, the nanowires are fixed by electrospinning on electrodes that are spaced from the surface at predetermined intervals, that is, lamps, or the nanowires are selectively grown from one electrode to the opposite electrode and airborne. A nanowire-based sensor was fabricated in a suspended form. The existing airborne nanowire sensors do not have sufficient sensitivity, the contact between the nanowires and the electrodes is not good, and the manufacturing process is difficult to control due to the complexity of the manufacturing process, resulting in a problem in yield reduction. In addition, the manufacturing method is expensive, or the manufacturing time is long, which limits the commercialization through mass production of the sensor.

[Non-Patent Documents]

(Non-Patent Document 1) S. Sharma, A. Sharma, Y.-K. Cho, Μ. Madou, Applied

Materials and Interface 2012, 4, 34-39.

[Detailed Description of the Invention]

[Technical Challenges]

Disclosure of Invention The present invention aims to provide a method for manufacturing a floating-type single carbon nanowire that can effectively improve the yield reduction and manufacturing limitations of the existing floating-type nanowire sensor. An object of the present invention is to provide a method for manufacturing a superposed nano-electrode pair, which is a male form of a wire.

Specifically, the present invention provides a method for preparing a floating single carbon nanowire to minimize the size of the floating single carbon nanowire in order to effectively improve the problems caused by the existing floating nanowires, and a thin and An object of the present invention is to provide a method for manufacturing a superposed nanoelectrode pair for forming a dense airborne carbon nanomesh.

In addition, the present invention is to provide a gas sensor or an electrochemical sensor applying the airborne type single carbon nanowires and superposed nano-electrode pair prepared according to the manufacturing method of the present invention.

[Technical Solution]

One embodiment of the present invention is a method for producing airborne single carbon nanowires

(a) depositing an insulating layer 11 on the substrate 10;

(b) coating a photoresist (12) on the insulating layer;

(c) first exposing the photoresist through a light-shaped photomask to form a photoresist light emitting part 13 on the insulating layer;

(d) micro-photoresist wires 14 connecting the photoresist lamps with each other by secondly exposing the upper portions of the photoresist between the lamps in the form of micro sized wires connecting the lamps through a wire-shaped photomask; Forming a;

(e) removing the photoresist of the remaining portions except for the portions exposed in the steps (c) and (d) by development; And

(f) the dorsal portion 13 and micro-sized wye remaining after step (e). Pyrolyzing the fish (14) to form an airborne single carbon nanowire (16),

The pyrolysis of step (f) is carried out in two stages, a first stage and a second stage, and the second stage is performed at a higher temperature than the first stage. (Figure 1)

The substrate 10 is not particularly limited in kind in terms of achieving the object of the present invention, preferably a silicon substrate, more preferably a silicon wafer may be used. In this case, when using a silicon wafer as a substrate, it is also possible to use 6 to 9 inches, which is a common size.

The insulating layer 11 deposited on the substrate in step (a) may be made of any material capable of preventing electrical connection between two carbon lamps 15, for example, made of silicon dioxide or silicon nitride. Can be. In addition, in the step (a), it is preferable to deposit an insulating layer on the entire upper surface of the substrate. At this time, the deposition may be carried out by a non-limiting method known to those skilled in the art, for example, it is possible to deposit by thermal oxidation method (Thermal oxidation).

When the substrate is used as the insulator in step (a), the step of depositing the insulating layer may be omitted. The insulator substrate material may be quartz or aluminum oxide or the like.

After depositing the insulating layer on the substrate in step (a), it is preferable to wash the insulating layer deposited by the cleaning process before performing the step (b). At this time, the specific method of washing is not limited. For example, washing with a Piranha solution (Piranha solution-sulfuric acid (H ₂ SO ₄ ): hydrogen peroxide (¾0 ₂ ) = 4: 1 mixed solution) is also possible. In step (b), the photoresist 12 is evenly coated on the insulating layer deposited on the substrate, wherein the coating may be performed by a non-limiting method known to those skilled in the art, for example, spin coating. It may be carried out by various methods such as dip coating or gravure coating. The photoresist coated in step (b) is not limited in principle as long as it can achieve the object of the present invention, it is preferable to use a negative photoresist including a SU-8 photoresist. The thickness of the photoresist coated at this time is 5 to 75 μηι, preferably 20 to 40 μηι.

After coating the photoresist in step (b), it is preferable to perform a soft bake on the insulating layer and the substrate in the state where the photoresist is coated before performing the step (c). At the end of the soft bake process, the substrate is naturally cooled to the same temperature as the silver before the above step is performed. After checking, perform the next step (c). The specific conditions of soft bake at this time correspond to the application for 1 to 15 minutes at 80 to 120 ^° C. In the step (c), the coated photoresist is exposed to ultraviolet rays through a columnar photomask window using a mask aligner to perform primary exposure. When the primary exposure is completed in this way, the photoresist is cured in a lamp shape on the upper portion of the insulating worm to form the photoresist lamp portion 13. At this time, the exposed light energy should be layered so that the photoresist can be cured from the top of the photoresist to just above the insulating layer.

After performing the first exposure of step (c), before exposure step (d), a post exposure bake is performed on the insulating layer and the substrate in which the photoresist light emitting part 13 is formed. It is preferable to. At this time, when the post exposure bake process is completed, the substrate is naturally cooled to confirm that the temperature is the same as the temperature before the step (a) is performed. The specific conditions of post exposure bake at this time correspond to 1 to 15 minutes and application at 80 to 120 ^° C.

In the step (d), the secondary exposure is performed by exposing the photoresist between the lamps to the ultraviolet through a photomask having a micro-sized wire-shaped window on the upper portion of the photoresist between the lamps. In the second exposure step, only the upper end of the photoresist can be cured by limiting the energy of the ultraviolet light absorbed by the photoresist to less than the first exposure. Through the secondary exposure, a portion of the photoresist between the photoresist light emitting portions is cured into a wire shape to form a micro photoresist wire 14 connecting the photoresist light emitting portions to each other. At this time, the micro photoresist wire is formed so as to support a predetermined interval from the insulating layer. After performing the second exposure of step (d), after the exposure to the insulating layer and the substrate in the state where the photoresist light emitting portion 13 and the micro photoresist wire 14 is formed before performing the step (e) It is desirable to proceed with a post exposure bake. At this time, when the post exposure bake process is completed, the substrate is naturally spontaneously sensed to confirm that the temperature is the same as the temperature before the step (a). If it is not sufficiently sensed, the photoresist light emitting part 13 and the micro photoresist wire 14 may be cracked or destroyed by thermal stress in the development step of step (e). The specific conditions of post exposure bake at this time correspond to the application for 1 to 15 minutes at 80 to 120 ^° C.

In the step (e), the remaining portions except the exposed portion and the photoresist are applied. Remove as phase. Through this photoresist development, only the micro photoresist wire 14 and the photoresist light emitting portion 13 in the suspended state remain. As a development method, various types of developers known to those skilled in the art can be used, and for example, a SU-8 developer may be used.

After the development of step (e) is carried out, it is preferable to wash the remaining part of development before the step (f). The specific method of washing in the washing is not limited, and it is also possible to sequentially wash, for example, isopropyl alcohol and methane.

In addition, there may be small particles that could not be removed despite the phenomenon of step (e). Therefore, after the development of step (e), the remaining small particles that were not removed in step (e) are cleaned using a photoresist asher before performing step (f). It is also desirable to remove.

In the step (f), the micro-resist wire 14 and the photoresist register 13 remaining after the step (e) are thermally decomposed to form an airborne type single carbon nanowire 16. At this time, the photoresist lamp is deformed into a carbon post (15) through pyrolysis, and the carbon lamp (15) causes the airborne type single carbon nanowires (16) formed by pyrolysis to be suspended from the insulating layer at a predetermined interval. do. The glass transition temperature of the micro photoresist wire 14 is about 250 ^° C. As the pyrolysis process proceeds, the organic gas due to pyrolysis escapes to the outside, thereby increasing the glass transition temperature, and thus the micro photoresist wire before the pyrolysis process. (14) and carbon nanowires 16 formed by pyrolysis do not differ in shape. 2, the micro photoresist wire 14 is thus transformed into carbon nanowires 16 without sagging. In addition, due to the volume reduction of the column portion supporting the micro photoresist wire 14 in the pyrolysis process, the wire formed by pyrolysis is subjected to tensile stress from both edges, thereby forming the airborne carbon wire (16). ) Will maintain a straight shape.

On the other hand, one object of the present invention is a method for producing a floating-type single carbon nanowires to minimize the size of the floating-type single carbon nanowires, the present inventors are characterized by the thermal decomposition of step (f) As a result, it has been found that the adoption of a particular type is more preferable for this purpose. The pyrolysis of step (f) is carried out in the first and second steps This is done in two stages, with the second stage at a higher temperature than the first stage. Specifically, the first step is carried out for 30 to 90 minutes at 300 to 400 ^° C, the second step is carried out at 600 to 1000 ^° C, preferably for 30 to 90 minutes at 900 to 1000 ^° C. . More specifically, the first step is performed while maintaining a temperature of 300 ^° C. to 1 ^° C./min (min) to 300 ^° C. to 30 ^° to 90 minutes at 300 ^° C. to 400 ^° C., and then to 600 ^° C. to 1000 ^° C. preferably it is 900 to 1000 ^° in the C 1 ^° C / minute (min) temperature increase is from 600 to 1000 ^° C to up to, and preferably 900 to 1000 ^° C maintained for 30 to 90 minutes in the second step and performed . 3 corresponds to a non-limiting example of the pyrolysis conditions of step (f), but is not limited thereto.

In addition, the pyrolysis temperature of the second step may be para-selectively adjusted to the electrical conductivity of the desired carbon nanowires. For example, the pyrolysis temperature of the second stage

When performed at 700 ° C, 800 ° C, and 900 ° C, the electrical conductivity at room temperature for carbon wires of thickness 400 nm, width 30 nm and length 10 μπι is 800 S / m, 1,900 S / m, 14,000 S may vary with / m.

As described above, a specific type of thermal decomposition is adopted as the characteristic of pyrolysis in step 0, because it exhibits the effect of minimizing residual stress while maximizing the volume change of the micro photoresist wire in the thermal process. Particularly in the specific form of the pyrolysis process, the volume change of the micro photoresist wire occurs mostly in the first step above 500 ^° C., so the tensile stress applied to the wire formed by pyrolysis is less than 500 V. It can be seen that the most occurs in the first step In addition, in the specific form of the pyrolysis process, even a high temperature of 600 to 1000 ^° C., preferably 900 to 1000 ^° C., is raised to 1: / min (min). Because of maintaining the structure for 30 to 90 minutes at 600 to 1000 ^° C, preferably at 900 to 1000 ^° C. It is expected that the amount of actual stress required to dissipate many of the stresses generated is small, and after the pyrolysis process, the formed nanowires are cooled in a natural angled manner, thus reducing the residual stresses due to the annealing effect. A decrease is also expected.

The specific atmosphere in which the pyrolysis of step (f) is to be reproduced is not particularly limited so long as it does not interfere with the reproduction of the specific type. For example, the micro photoresist wire 14 and the photoresist formed in step (e). the Insert a gideung portion 13 in an electric furnace using a low vacuum pumps, high vacuum pump, create the atmosphere to ^10-7 to ^10-5 Torr (torr) can be reproduced that of the particular type. After the step (f), the airborne type single carbon nanowires 16 formed by pyrolysis are naturally carved out and removed from the atmosphere of pyrolysis. In addition, photoresist st ashers are preferably used to remove carbon particles generated during pyrolysis.

The airborne type single carbon nanowires produced by the above production method has a thickness of 250 nm or less, a width of 250 nm or less, preferably a thickness of 180 to 240 nm, and a width of 170 to 220 nm. In addition, the manufacturing method is generally simpler and more economical than the conventional method of manufacturing the airborne nanowires, and thus the yield of the final airborne single carbon nanowires formed is 75¾ or more, preferably 90% or more. Corresponding. Therefore, the manufacturing method is remarkable in that it provides a high yield of airborne type single carbon nanowires with a minimized size.

In addition, the carbon content of the airborne type single carbon nanowires prepared by the above production method is 95% or more, preferably 98% or more. Usually, in order to pyrolyze polymer precursors to form carbon nanowires containing 100% of carbon, substantial high temperature conditions of 2000 ° C are theoretically required, but in general, the thermal decomposition of polymer precursors is almost complete at around 1000 ^° C. In order to realize the high carbon content, there has been a technical difficulty in using external conditions other than pyrolysis. However, according to the manufacturing method of the present invention adopting a specific type as a characteristic of the thermal decomposition, there is an effect that the high carbon content of the carbon nanowires is implemented even if the thermal decomposition is completed at an appropriate high temperature conditions around 1000 ^° C. This again supports that the specific form is the optimized form as the thermal decomposition conditions of the production method of the present invention. Furthermore, by stacking a gas sensing material or an electrochemical sensing material on the airborne type single carbon nanowire manufactured by the manufacturing method, the gas sensor is applied to the airborne type single carbon nanowire with improved sensitivity and reduced size and volume. Or an electrochemical sensor may be provided. The gas sensing material is not particularly limited as long as it adopts various ones known to those skilled in the art, but it is preferable to adopt a material whose conductivity is changed to a specific gas such as palladium or platinum. Palladium or platinum can improve the gas sensor's sensitivity and reduce the thermal stress of carbon nanowires. The electrochemical sensing material is also not limited as long as it adopts a variety of known to those skilled in the art. Another embodiment of the present invention is a method of manufacturing a superposed nano-electrode pair (a) depositing an insulator 51 on the substrate 50;

(b) first coating a photoresist (52) on the insulating layer;

(c) firstly exposing the first coated photoresist through a planar electrode-shaped photomask to form a photoresist planar electrode portion 53 on the insulating layer;

(d) removing the photoresist of portions other than the portions exposed in step (c) by development;

(e) secondary coating a photoresist (54) on the insulating layer and the planar electrode portion remaining after the step (d);

(f) secondly exposing the second coated photoresist through a light-shaped photomask to form a photoresist light emitting portion 55 on the insulating layer;

(g) micro-photoresist wires 56 connecting the photoresist lamps with each other by exposing the upper portions of the photoresist between the lamps in the form of micro sized wires connecting the pillars through a wire-shaped photomask; Forming a;

(h) removing the photoresist of portions other than the portions exposed in step (g) by development; And

(i) thermally decomposing the planar electrode part 53, the lamp part 55, and the micro-sized wire 56 remaining after the step (h) to form the planar electrode 57 and the airborne carbon nanomesh 59 Forming a)

The pyrolysis of step (i) is carried out in two stages, a first stage and a second stage, and the second stage is performed at a higher temperature than the first stage. (Figure 4)

The substrate 50 is not particularly limited in kind in terms of achieving the object of the present invention, preferably a silicon substrate, more preferably a silicon wafer can be used. In this case, when using a silicon wafer as a substrate, it is also possible to use 6 to 9 inches, which is a common size.

The insulating layer 51 deposited on the substrate in step (a) may be made of any material capable of preventing electrical connection between the two carbon lamps 58 and the planar electrode 57, for example, silicon dioxide or It may be made of silicon nitride. In addition, in the step (a), it is preferable to deposit an insulating layer on the entire upper surface of the substrate. At this time, the deposition may be carried out by a non-limiting method known to those skilled in the art, for example, it is possible to deposit by thermal oxidation method (Thermal oxidation). When the substrate is used as the insulator in step (a), the step of depositing the insulating layer may be omitted. The insulator substrate material may be quartz or aluminum oxide or the like.

After depositing the insulating layer on the substrate in step (a), it is preferable to wash the insulating layer deposited by the cleaning process before performing the step (b). At this time, the specific method of washing is not limited. For example, washing with a Piranha solution (Piranha solution-sulfuric acid (H ₂ SO ₄ ): hydrogen peroxide (¾0 ₂ ) = 4: 1 mixed solution) is also possible. In the step (b), the photoresist 52 is uniformly first coated on the insulating layer deposited on the substrate, and the coating may be performed by a non-limiting method known to the skilled person, for example. It can be carried out by various methods such as spin coating, dip coating, or gravure coating. The photoresist coated in the step (b) is not limited in principle, but it is preferable to use a negative photoresist including a SU-8 photoresist. At this time, the thickness of the first photoresist to be coated is 2 to 10 μπι, preferably 3 to 8 μπι.

After the first coating of the photoresist in the step (b), before performing the step (c), it is preferable to perform a soft bake on the insulating layer and the substrate in the state where the photoresist is first coated. . At this time, when the soft bake process is finished, the substrate is sufficiently natural to check that the substrate is in the same state and temperature as before the step (a), and then the step (c) is performed. . The specific conditions of soft bake at this time correspond to application at 80 to 120 ^° C for 1 to 15 minutes.

In the step (c), the primary coated photoresist is exposed to ultraviolet rays through a photomask window in the form of a planar electrode to perform the primary exposure. As such, when the primary exposure is completed, the photoresist coated with a primary shape in the form of a flat electrode is cured on the upper portion of the insulating layer to form the photoresist flat electrode part 53. At this time, the exposed optical energy should be layered so that the photoresist can be cured from the top of the photoresist to just above the insulating layer.

In the step (d), the photoresist of the remaining portions except for the portion exposed in the step (c) is removed by development. If the development of step (d) is not performed, chemical destruction may occur due to chemical breakdown of the flat electrode part, the lamp part, and the micro-sized wire formed while the development time of step (h) takes a long time. It is essential to proceed. Step (d) Only the flat electrode portion remains through the photoresist development of. As a method of development, various kinds of developers known to those skilled in the art can be used, and for example, SU-8 developer may be used.

In addition, it is another aspect to omit the step (d) and to remove the photoresist of the remaining portions except the portions exposed in the steps (c) and (g) by the development at the same time in the step (h). Is possible.

In step (e), the photoresist 54 is second-coated on the insulating layer and the planar electrode part remaining after step (d). At this time, the coating may be performed by a non-limiting method known to those skilled in the art, for example, may be performed by various methods such as spin coating, dip coating, or gravure coating. The photoresist that is secondary coated in step (e) is not limited in principle, but it is preferable to use a negative photoresist including a SU-8 photoresist. At this time, the thickness of the photoresist coated with the secondary is 5 to 75 μπι, preferably 20 to 40 μπι, and is formed thicker than the photoresist coated first in step (b).

After the second coating of the photoresist in the step (e), before the step (f) is carried out, the bake is softly baked on the planar electrode portion, the insulating layer, and the substrate in which the photoresist is coated second Is preferred. At this time, when the soft bake process is terminated, the substrate is sufficiently spontaneously modified to confirm that the temperature is the same as the temperature before the step (a), and then the step (f) is performed. The specific conditions of soft bake at this time correspond to the application for 1 to 15 minutes at 80 to 120 ^° C.

In the step (f), the secondary coated photoresist is exposed to ultraviolet rays through a columnar photomask window to perform secondary exposure on both sides of the planar electrode part. When the secondary exposure is completed in this manner, the photoresist is cured in a columnar shape on the upper portion of the insulating layer, and photoresist pillars 55 are formed on both sides of the planar electrode portion 53. At this point, the exposed light energy should be layered enough to cure the photoresist from the top of the photoresist to just above the insulating layer.

After performing the second exposure of the step (f), before the step (g), after exposing the flat electrode portion 53, the insulating layer and the substrate in the state where the photoresist light emitting part 55 is formed It is desirable to proceed with a post exposure bake. If the end of this time the post-exposure baking (t _pos exposure bake) process, the substrate layer sufficiently to natural nyaenggak the step (a) Make sure that the temperature is the same as the degree of silver before performing. The specific conditions of post exposure bake at this time correspond to the application for 1 to 15 minutes at 80 to 120 ^° C.

In the step (g), a third exposure is performed in which the upper portion of the photoresist between the light emitting portions 55 is exposed to ultraviolet rays through a photomask having a micro-sized wire window. In the third exposure step, the energy of the ultraviolet light absorbed by the photoresist is limited to less than the second exposure so that only the upper end of the photoresist can be cured. Through the third exposure, a portion of the photoresist between the photoresist light emitting portions is cured into a wire shape to form a micro photoresist wire 56 connecting the photoresist light emitting portions to each other. At this time, the micro photoresist wire 56 is formed so as to support a predetermined interval from the insulating layer.

On the other hand, the manufacturing method and purpose of the superposed nano-electrode pair according to the present invention is to form a thin and dense airborne carbon nano mesh 59, between the wire of the wire-type photomask of the step (g) It is more preferable to achieve the above object that the angle of Θ is in the range of 40 to 60 degrees. As also disclosed in FIG. 5, the carbon nanomesh that is finally formed when the range of 40 to 60 degrees is adopted as the angle Θ between the wires of the photomask used for the third exposure of the step (g) is adopted. You can see the compact form.

After performing the third exposure of step (g), before performing the step (h), the planar electrode part 53 in which the photoresist light emitting part 55 and the micro photoresist wire 56 are formed, It is preferable to perform post exposure bake on the insulating layer and the substrate. At this time, when the post exposure bake process is completed, the substrate is sufficiently cooled to confirm that the temperature is the same as the temperature before the step (a). If not sufficiently cooled, the planar electrode portion 53, the photoresist light emitting portion 55, and the micro photoresist wire 56 are subjected to thermal stress in the development stage of step (h) to cause cracks or breakage. Because it may. The specific conditions of post exposure bake correspond to the application for 1 to 15 minutes at 80 to 120 ^° C.

In the step (h), the photoresist of the remaining portion except for the exposed portion is removed by development. Through this photoresist development, the microphotoresist wire 56, the photoresist pillar portion 55 and the flat state of the suspended state Only the surface electrode portion 53 remains. As a development method, various types of developers known to those skilled in the art can be used. For example, a SU-8 developer may be used.

After performing the development of the step (h), it is preferable to wash the remaining part of the development before performing the step (i). The specific method of washing in washing is not limited, and it is also possible to sequentially wash, for example, isopropyl alcohol and methane.

In addition, there may be small particles that could not be removed despite the phenomenon of step (h). Therefore, after the development of the step (h), the photoresist asher is used before the step (i).

It is also desirable to clean the remaining small particles that could not be removed in step (h).

In the step (i), the micro-resist wire 56, the photoresist lamp part 55, and the planar electrode part 53 remaining after the step (h) are thermally decomposed to form the planar electrode 57 and the airborne carbon nanoparticles. 6, the flat electrode 57 and the airborne carbon nanomesh 59 may be identified as superimposed nano electrode pairs that form a mesh 59 and are formed by pyrolysis. At this time, the photoresist pillar portion 55 is transformed into a carbon post 58 through pyrolysis, and the planar electrode portion 53 is transformed into a flat electrode 57 through pyrolysis. ) Causes the airborne type carbon nanomesh 59 formed by pyrolysis to be floated from the insulating layer by a predetermined interval. In addition, in the pyrolysis process, the micro photoresist wire 56 is deformed into carbon nanomesh 59 without sagging, and in the pyrolysis process, pyrolysis also occurs in the lamppost supporting the micro photoresist wire 56. This is because the nanomesh formed is subjected to tensile stress from both edges.

On the other hand, the object of the manufacturing method of the superposed nano-electrode pair according to the present invention is to form a thin and dense airborne carbon nanomesh,

It has been found that it is more preferable for this purpose to adopt certain types of features as a characteristic of the pyrolysis of step (i). The pyrolysis of step (Π) is carried out in two stages, the first stage and the second stage, and the second stage is carried out at a higher temperature than the first stage. Specifically, the first stage is performed at 300 to 400 ^° C. To 90 minutes, and the second step is carried out at 600 to 1000 ^° C., preferably at 900 to 1000 ^° C. for 30 to 90 minutes, more specifically 1 ^° C./min to 300 to 400 ^° C. (min) has been won within 300 Not at 400 ^° C while maintaining 30 to 90 minutes is the first step used which after which the temperature was raised with 1 ^° C / minute (min) up to 600 to 1000 ^° C, to preferably from 900 to 1000 ^° C 600 The second step is carried out at -1000 ^° C, preferably at 30-90 minutes at 900-1000 ^° C.

The specific atmosphere in which the pyrolysis of step (i) is to be reproduced is not particularly limited so long as it does not prevent the reproduction of the specific type, and for example, the micro photoresist wire 56, the photoresist pillar portion 55 and Insert the flat electrode portion 53 in an electric furnace after all, only a low atmosphere to vacuum and using a high vacuum pump ^10-7 to ^10-5 Torr (torr) can be reproduced that of the particular type.

After the step (i), the planar electrode 57 and the hollow core-type carbon nanomesh 59 formed by pyrolysis are naturally observed and then removed from the atmosphere of pyrolysis. In addition, a photoresist asher may be preferably used to remove carbon particles generated during the pyrolysis process.

The airborne carbon nanomesh prepared by the above production method has a width of 200 to 400 nm and a carbon nanowire spacing of 3 to 7 μπι. In addition, since the manufacturing method is simple and economical as it is an application form of the method for preparing a floating-type single carbon nanowire according to the present invention, the yield of the overlapping nano-electrode pairs to be formed is 70% or more, preferably 80%. It corresponds to the above high yield. Therefore, the manufacturing method has a remarkable effect of providing a thin and dense airborne carbon nanomesh in high yield.

Furthermore, by stacking a gas sensing material or an electrochemical sensing material on the superposed nanoelectrode pair manufactured by the manufacturing method, a gas sensor or an electrochemical sensor is applied to the superposed nano electrode pair with improved sensitivity and reduced size and volume. May be provided. In this case, the gas sensing material or the electrochemical sensing material may be laminated on both the planar electrode and the airborne carbon nanomesh constituting the superposed nano-electrode pair, and may be laminated only on one side. The gas sensing material is not particularly limited as long as it adopts various ones known to those skilled in the art, but it is preferable to adopt a material whose conductivity is changed to a specific gas such as palladium or platinum. Palladium or platinum can improve the sensitivity of the gas sensor and reduce the thermal stress of carbon nanowires. The electrochemical sensing material is also not limited as long as it adopts a variety of known to those skilled in the art.

Advantageous Effects

Method for producing a floating airborne single carbon nanowire according to the present invention is 250 nm thick It provides a high yield of airborne single carbon nanowires with a minimum size of 250 nm or less in width, and implements a high carbon content of carbon nanowires produced by thermal decomposition under appropriate high temperature conditions. Therefore, the airborne single carbon nanowire according to the present invention is expected to effectively improve the yield reduction and manufacturing limitations of the existing airborne nanowire sensors.

The method of manufacturing a superposed nanoelectrode pair according to the present invention has the effect of providing a thin and dense airborne carbon nanomesh with high yield.

The airborne single carbon nanowires and superposed nanoelectrode pairs have excellent electrical, mechanical, and electrochemical properties, and thus may be applied to gas sensors or electrochemical sensors of an improved form than conventional ones. .

[Brief Description of Drawings]

FIG. 1 is a view illustrating a manufacturing process of a notarized single carbon nanowire. Figure 2 compares the structural shape of the carbon nanowires formed by pyrolysis with the micro photoresist wire of the pyrolysis process 제조 in the method of manufacturing airborne single carbon nanowires.

Figure 3 corresponds to an example of pyrolysis conditions in the manufacturing method of airborne single carbon nanowires.

4 is a view illustrating a manufacturing process of a method of manufacturing a superposed nanoelectrode pair. Figure 5 shows the density of the carbon nanomesh finally formed according to the angle (Θ) between the wires of the photomask in the third exposure step of the manufacturing method of the superposed nano-electrode pair.

FIG. 6 illustrates a planar electrode and an airborne carbon nanomesh as a superposed nanoelectrode pair formed by a method of manufacturing a superposed nanoelectrode pair.

FIG. 7 analyzes the binding and quantification of carbon (left), oxygen (right), and other elements of airborne carbon nanomeshes using X-ray photoelectron spectroscopy (XPS). ᅳ

FIG. 8 shows the shape of a dense airborne carbon monanomesh finally formed by Example 3. FIG.

9 is a result of confirming the crystallinity of the airborne type single carbon nanowires using a transmission electron microscope.

Figure 10 shows the results of the stress analysis generated in the airborne type single carbon nanowires by the applied voltage. FIG. 11 shows the electrochemical characteristics of the airborne single carbon nanowires through cyclic-current voltage experiments and their characteristics as an electrochemical sensor of the airborne structure. Specifically, (a) shows the results of electrochemical characterization of airborne single carbon nanowires through cyclic volta 隱 etry experiments, and (b) shows the results of concentration distribution analysis of airborne single carbon nanowires. (10 mM Ferrocyanide in 0.5 M KC1) and (c) show the concentration distribution analysis results (10 mM Ferrocyanide in 0.5 M KC1) of the planar electrode carbon nanowire.

[Description of the code]

10: substrate 11: insulating layer

12: photoresist 13: photoresist pillar

14: micro photoresist wire 15: carbon pillar

16: Airborne Single Carbon Nanowires

50: substrate 51: insulating layer

52: primary coating photoresist 53: photoresist flat electrode portion

54 ： Secondary coating photoresist 55: Photoresist light register

56: micro photoresist wire 57: flat electrode

58: carbon column 59: airborne carbon nanomesh

[Best form for implementation of the invention]

Hereinafter, specific embodiments of the present invention will be described in detail. Prior to this, the terms or words used in the specification and claims of the present invention should not be construed as being limited to ordinary or dictionary meanings, and the inventors should understand the concept of terms in order to install their own invention in the best way. Based on the principle that can be properly defined, it should be interpreted as meanings and concepts corresponding to the technical spirit of the present invention.

Therefore, the embodiments described in the specification of the present invention and the configuration shown in the drawings are only the most preferred embodiments of the present invention, and do not represent all of the technical ideas of the present invention, so at the time of filing of the present invention, It should be understood that there are equivalent variations that can be substituted.

Example 1 Preparation of Airborne Type Single Carbon Nanowires

Silicon dioxide was deposited by thermal oxidation on a typical 6-inch silicon wafer, followed by a cleaning process (Piranha solution-sulfuric acid (¾S0 ₄ ): hydrogen peroxide (H ₂ 0 ₂ ) = 4 : l mixed solution)). Photoresist After SU-8 was uniformly coated with a thickness of 25 iim on the insulating layer by spin coating, a soft bake was performed at 95 ^° C. for 9 minutes. After a soft bake, the silicon wafer was naturally cooled down to confirm that it was at the same temperature as the initial state. After the silicon wafer has been cooled down sufficiently, the mask aligner is used to expose the ultraviolet light through a pillar-shaped photomask window to perform the first exposure, and after exposure at 95 ^° C. for about 3 minutes, baking ( After the post exposure bake, the silicon wafer was sliced again. After further cooling the silicon wafer again, secondary exposure was performed by exposing the silicon wafer to ultraviolet rays through a wire-shaped photomask. After performing the second exposure, after the post exposure bake at 95 ^° C. for about 3 minutes, the silicon wafer was again cooled down. After sufficiently etching the silicon wafer, the remaining portions except the exposed portions were removed by development using a SU-8 developer (SU-8 developer). After developing, sequential washing with isopropyl malco and methanol, and small particles that could not be removed in the developing step are removed, and the remaining small particles that cannot be removed by using a photoresist asher are cleaned. did. Put the clean micro SU-8 wire and the SU-8 lamp into an electric furnace and use a low vacuum pump and a high vacuum pump.

After the atmosphere was made up to ⁶ torr, pyrolysis was carried out in two stages, the first stage and the second stage. Specifically it is raised by 1 ^° C / minute (min) since, as was conducted for the first stage is raised maintained for 60 minutes at 350 ^° C as is 1 ^° C / min to 900 ^° C (min) to 350 ^° C The second stage was carried out while maintaining 60 minutes at 900 ^° C. The aerial type single carbon nanowires formed after pyrolysis were naturally cooled and then removed from the electric furnace, and the carbon particles generated during the pyrolysis process were removed using a photoresist asher.

Example 2 Physical property analysis of airborne type single-stage tasonano wire of Example 1

The airborne type single carbon nanowires finally produced by Example 1 have a yield of 90%. The shape and structural features of the airborne single carbon nanowires are shown in SEM (Quanta 200, FEI company USA), HRTEM (JEM-2100F, JE0L Ltd., Japan), FIBCQuanta 3D FEG, FEI company, USA), and Raman spectroscopy system. (alpha300R, WITec GmbH, Germany). The airborne type single carbon nanowires have a measured thickness of 210 nm and a width of 195 nm. In addition, X-ray photoelectron spectroscopy was used to measure the carbon content of the prepared airborne single carbon or no-wire. Since the range of magnetic spectroscopy is several microns, it is not easy to measure ¾ middle-type single carbon nanowires directly. As a result, many changes were observed before and after pyrolysis in cc, C-0, and 0 content, and the carbon content after pyrolysis was 96.9%. Specifically, as shown in FIG. 7, CC content was increased after pyrolysis, and C-0 and 0-0 contents were confirmed to be hardly present.

Comparative Example 1

It proceeded in common with Example 1 except that a single step of 2 minutes at 300 ^° C. was applied under pyrolysis conditions.

Comparative Example 2

It proceeded in common with Example 1 except that a single step of 2 minutes at 350 ^° C. was applied under pyrolysis conditions.

Comparative Example 3

It proceeded in common with Example 1 except that a single step of 2 minutes at 400 ^" C was applied as pyrolysis conditions.

[Comparative Example 4]

It proceeded in common with Example 1 except for applying a single step of 2 minutes at 450 ^° C as pyrolysis conditions.

[Comparative Example 5]

It proceeded in common with Example 1 except that a single step of 2 minutes at 500 t was applied under pyrolysis conditions.

Comparative Example 6

It proceeded in common with Example 1 except that a single step of 60 minutes at 500 ^° C. was applied under pyrolysis conditions.

[Comparison of Example 1 and Comparative Examples] [Table 1]

According to the production method of the present invention adopting a specific form of the thermal decomposition conditions as shown in Table 1, it can be seen that the size of the airborne type single carbon nanowires are minimized to less than 250 nm in width. This supports that the specific form is optimized form by the thermal decomposition conditions of the production method of the present invention.

Example 3 Preparation of Foldable Nano-pole Pair

Silicon dioxide was deposited by thermal oxidation on a common 6-inch silicon wafer by thermal oxidation, and then SU-8, a photoresist, was evenly coated on the insulating layer with a thickness of 7 μηι. After the first coating of SU-8, the first exposure was performed by sufficiently exposing to ultraviolet rays through a photoelectrode window in the form of a flat electrode, and the first exposed portion using a SU-8 developer (SU-8 developer). The rest was removed as a development. After development, the photoresist S 8 was evenly coated with a thickness of 25 μιη on the insulating layer and the flat electrode by spin coating. After the SU-8 secondary coating sufficiently exposed to ultraviolet light through a photo mask window of gideung shape perform a second exposure and, by the angle _(θ) between the wire exposed sufficiently layer to ultraviolet radiation through ₄₅ degrees photomasks Third exposure was performed. After the third exposure, the remaining portions except the exposed portions were removed by development using a SU-8 developer (SU-8 developer). After the development, the micro SU-8 wire, the SU-8 lamp and the SU-8 flat electrode were placed in an electric furnace to create an atmosphere of 1 to ⁶ torr using a low vacuum pump and a high vacuum pump. Pyrolysis was carried out in two stages. Specifically, the temperature was raised with 1 ^° C / minute (min) of claim 1 ^° C / minute up to 900 ^° C since, has, proceed to step 1 (min) while the temperature was raised maintained for 60 minutes at 350 ^° C to up to 350 ^° C Proceed with the second step while maintaining 60 minutes at 900 ^° C. Planar electrode and airborne carbon nanomesh formed after pyrolysis After cooling it was removed from the furnace.

Example 4 Physical property analysis of superposed nanoelectrode pairs

The overlapping nano-electrode pair finally formed by Example 3 has a yield of 75%. The shape and structural features of the airborne carbon nanomesh are SEM (Quanta 200, FEI company USA), HRTEMCIEM— 2100F, JEOL Ltd., Japan), Quanta 3D FEG, FEI company, USA (FIB), and Raman spectroscopy system ( alpha300R, WITec GmbH, Germany). The measured width of the airborne carbon nanomesh corresponds to 300 nm and the carbon nanowire spacing corresponds to 4.5 μηι. (Figure 8)

Example 5 Investigation of Resistant Characteristics of Airborne Type Single Carbon Nanowires of Cympic Example 1 FIG. 9 illustrates the crystallinity of airborne type single carbon nanowires using a transmission electron microscope. The higher the ratio of graphitic phases, the smaller the energy bandgap is known to be, and the transmission of the graphitic phase at the edge of the electron microscope image was found to be higher than the central portion. Although the temperature of the pyrolysis process is lower than the temperature at which the graphitic phase is formed, about 20% of the graphitic phase is present in volume ratio, which has high electrical conductivity despite being glassy carbon. Means that.

Example 6 Observation of mechanical properties of airborne single carbon nanowire of Example 1 The results of the stress generated in the airborne single carbon nanowire by applied voltage are shown in FIG. 10. The volume expansion rate of carbon nanowires according to temperature uses general carbon volume expansion rate data. The force is also the highest at the center of the nanowire and the maximum stress analysis result according to the applied voltage is shown in the graph of FIG. 10. Volume expansion with temperature increases compressive stress in airborne single carbon nanowires, but the maximum compressive stress up to IV does not reach the actual stress of fracture of carbon. This means that the airborne type single carbon nanowires prepared in Example 1 have excellent mechanical properties.

Example 7 Observation of Hypochemical Properties of Airborne Type Single Tasonano Wire of Example 1

Electrochemical Characteristics of Airborne Single Carbon Nanowires Using Cyclic-Current Voltage Experiments Figure 11 shows the characteristics of the electrochemical sensor of the sex and airborne structure. In order to confirm the electrochemical characteristics of the airborne single carbon nanowires, cyclic-voltage current experiments were conducted to confirm that they had high diffusion limit currents. In order to confirm the structural difference between the airborne electrode and the planar electrode, the concentration distribution by redox reaction was simulated using the Comsol Multiphysics program, and the airborne nanowires were compared to the planar nanowires having the same cross-sectional area. It was confirmed that a diffusion limit current was generated per unit length of more than twice. It was also confirmed that when the nanowires were located at least a certain distance (> 8 urn) away from the substrate, they generated almost the same current signal as the nanowires located at least tens of urns away from the substrate. Therefore, it is possible to fully utilize the advantages of the airborne structure without the need to separate the nanowires from the substrate by several tens of _microns . This means that the airborne type single carbon nanowires prepared in Example 1 have excellent electrochemical properties.

Claims

[Claim]

[Claim 1]

(a) depositing an insulating layer on the substrate;

(b) coating a photoresist on the insulating layer;

(c) first exposing the photoresist through a pillar-shaped photomask to form a photoresist lamp on the insulating layer;

(d) secondly exposing the upper portions of the photoresist between the lamps in the form of micro sized wires connecting the pillars through a wire-shaped photomask to form micro photoresist wires connecting the photoresist pillars to each other; step ;

(f) thermally decomposing the lamp and the micro-sized wire remaining after the step (e) to form an airborne single carbon nanowire,

The pyrolysis of the step ω is performed in two steps, a first step and a second step, wherein the second step is carried out at a higher temperature than the first step.

[Claim 2]

The method of claim 1,

Said substrate is a silicon substrate is a method of manufacturing a floating type single carbon nanowires.

[Claim 3]

The method of claim 1,

The insulating layer is a method for producing a floating airborne single carbon nanowires made of silicon dioxide or silicon nitride.

[Claim 4]

The method of claim 1,

The photoresist is SU-8 floating airborne type carbon nanowire manufacturing method.

[Claim 5]

According to the clause 1

In the pyrolysis of step (f), the first step is performed for 30 to 90 minutes at 300 to 400 ^° C., and the second phase of the floating phase is performed for 30 to 90 minutes at 600 to 1000 ^° C. Method for producing a single carbon nanowire.

[Claim 6]

The method of claim 5, wherein the thickness of the airborne carbon nanowires is 250 nm or less, and the width of the airborne type carbon nanowires is 250 nm or less.

[Claim 7]

The method of claim 6,

The thickness is 180 to 240 nm, the width is 170 to 220 nm airborne type single carbon nanowire manufacturing method.

[Claim 8]

(a) terminating the insulating layer on the substrate;

(b) first coating a photoresist on the insulating layer;

(c) first exposing the first coated photoresist through a planar electrode shaped photomask to form a photoresist planar electrode portion on the insulating layer;

(e) secondary coating a photoresist on the insulating layer and the planar electrode portion remaining after the step (d);

(f) secondly exposing the second coated photoresist through a light-shaped photomask to form a photoresist pillar on the insulating layer;

(g) tertiary exposure of the photoresist between the light emitting portions in the form of a micro-sized wire connecting the light emitting portions through a wire-shaped photomask to form micro photoresist wires connecting the photoresist pillars to each other; step ;

(i) thermally decomposing the planar electrode portion, the lamp portion, and the micro-sized wire remaining after the step (h) to form a planar electrode and an airborne carbon nanomesh;

The pyrolysis of step (i) is carried out in two steps, the first step and the second step, wherein the second step is performed at a higher temperature than the first step.

[Claim 9]

The method of claim 8, Said substrate is a silicon substrate, the method of cleaning a nested nano-electrode pair.

[Claim 10]

The method of claim 8,

The insulating layer is a method of manufacturing a folding nano-electrode pair consisting of silicon dioxide or silicon nitride.

[Claim 11]

The method of claim 8,

The primary coating and the secondary coated photoresist is SU-8 manufacturing method of the superposed nano-electrode pair.

[Claim 12]

The method of claim 8,

The secondary coated photoresist is thicker than the primary coated photoresist forming method of manufacturing a pair of nano-electrodes.

[Claim 13]

The method of claim 8,

The angle (Θ) between the wire of the wire-shaped photomask is a method of manufacturing a superposed nano-electrode pair is 40 to 60 degrees.

[Claim 14]

The method of claim 8,

The first step is performed for 30 to 90 minutes at 300 to 400 ^° C., The second step is performed for 30 to 90 minutes at 600 to 1000 X: Method of manufacturing a superposed nano-electrode pair.

[Claim 15]

_. The method of claim 14,

The method of manufacturing a superposed nano-electrode pair having a width of the airborne carbon nano mesh is 200 to 400 nm, carbon nanowire spacing of 3 to 7 um.