KR20150026012A - GAS SENSOR and Method for Manufacturing GAS SENSOR - Google Patents

Abstract

The present invention relates to a manufacturing method for a gas sensor, which comprises: a) a step of forming a photoresist wire which connects a separated pair of photoresist electrodes and the pair of photoresist electrodes with each other, by exposing light and developing a first photoresist coated on a substrate; b) a step of forming a pair of carbon electrodes and a pair of carbon wires which are integrated with each other, by pyrolyzing the pair of photoresist electrodes and the photoresist wire; c) a step of forming a photoresist sacrificial layer which covers the pair of carbon electrodes and exposes the carbon wires, by coating a second photoresist on the substrate where the pair of carbon electrodes and the pair of carbon wires are formed and by exposing the coated second photoresist to light and developing the second photoresist; d) a step of forming a metal oxide seed on the carbon wire exposed by the photoresist sacrificial layer and then removing the photoresist sacrificial layer; and e) a step of forming a metal oxide nanowire on the surface of the carbon wire by growing the metal oxide seed.

Description

Technical Field [0001] The present invention relates to a gas sensor,

The present invention relates to a method of manufacturing a gas sensor, and more particularly, to a method of manufacturing a gas sensor which has excellent sensitivity, has excellent electrical contact between a nanowire for detecting a gas and an electrode, And a manufacturing method thereof.

In recent years, sensors for various gases have been developed along with an increase in interest in environmental problems and the development of information and communication devices, and manufacturing has been simplified and performance is improved by incorporating semiconductor technology. For all sensors, the goal is to increase the sensitivity to improve performance, and efforts are being made to achieve these goals.

On the other hand, in the conventional semiconductor type gas sensor, there is a limitation on the sensitivity because the sensing material is a semiconductor thin film. For example, in the case of stable chemical substances such as carbon dioxide, detection is almost impossible.

Therefore, sensors for detecting harmful gases such as carbon monoxide (CO) and carbon dioxide are applied by an electrochemical method using a conductive method of a solution, an optical method using an infrared absorption method, and a method of measuring the electrical resistance of nanoparticles or nanowires .

The electrochemical method utilizes an electromotive force generated by the action of ions in a gas phase formed by electrolytically oxidizing or reducing a target gas to measure an electric current flowing in an external circuit or dissolving or ionizing an electrolyte solution or a solid. It has a very slow reaction rate and has a disadvantage that the detection range of the gas and the use environment are limited and the price is also high.

In addition, the optical method by the infrared absorption method is advantageous in that it is hardly influenced by other mixed gas or humidity, but it is disadvantageous in that the apparatus is complicated, the size is increased, and the price is also high.

In general, the chemical sensor has a structure for sensing gas by a contact combustion method. When a gas reacts with a sensor including a platinum wire as a catalyst, the gas is converted into a gas by using the resistance change of the platinum wire by an exothermic reaction or an endothermic reaction And the stability and sensitivity of the sensor are improved.

In recent years, oxide semiconductor type gas sensors have been developed and commercialized as the relationship between the contact reaction by gas chemisorption and the electron density has been clarified. Such semiconductor type gas sensors detect most gases including flammable gases So that it is possible to achieve miniaturization, reduction in cost, and improvement of reliability compared with other types of gas sensors.

In the gas sensor using the carbon nanotube used as the semiconductor type gas sensor, other sensors are required to heat up to about 300 ° C. in order to detect nitrogen oxide and the like. However, the carbon nanotube can operate at room temperature, Because the particle size is nanometer, the sensitivity of the sensor is several thousand times higher than other sensors.

A gas sensor of the type that measures the electrical resistance change of the nanoparticle itself or the material coated with the nanoparticle according to the concentration of the measuring gas has been developed. The use of nanoparticles results in a very high sensitivity because of the very high volume to area ratio, which is highly effective in changing the effect of the surface reaction on the total volume of the gas depending on the change in gas concentration.

Conventional nanoparticles or sensors using nanowires are disclosed in Korean Patent Registration No. 10-0655640 (Dec. 4, 2006), in which an electrode capable of measuring the change in electrical resistance of these nanomaterials only at specific portions is irregularly dispersed The electrical resistance was measured by flowing nanomaterials on the electrodes or pre-patterned electrodes, or by contacting them with electrodes using electrophoresis.

The conventional semiconductor type gas sensor has disadvantages 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 the gas sensing process.

Thereafter, the nanowires are fixed by electrophoresis on a pole-shaped electrode spaced apart from the surface, or nanowires are selectively grown from one electrode to the opposite electrode to form nanowire-based sensors Respectively. However, it is difficult to control the manufacturing process because the contact between the nanowire and the electrode is difficult, and the manufacturing method is expensive, or the manufacturing time is long, so that the conventional nanowire sensor has a limitation in commercialization through mass production of the sensor .

Korean Patent No. 10-0655640

The present invention is to provide a method of manufacturing a gas sensor in which a carbon wire excellent in physical and chemical properties and a functional metal oxide nanowire having a varying electrical conductivity according to a gas concentration are integrated.

In addition, it is also possible to fabricate the carbon wires at a predetermined distance from the substrate so as to solve the problem of reduction in sensitivity and noise caused by influences from the substrate, which is a problem of a nanowire-based gas sensor attached to a conventional substrate, Wherein the metal oxide nanowire is free from the influence of the substrate by growing a metal oxide nanowire as a gas sensing material.

At this time, the carbon electrode and the carbon wire are integrally formed so that the contact between the carbon wire spaced from the substrate and the two carbon electrodes supporting the carbon wire is physically and electrically stable, and the two carbon electrodes are electrically connected only through the carbon wire So that the change in resistance between the two carbon electrodes is governed by the resistance change of the metal oxide nanowires coated with carbon wires.

The metal oxide nanowire is radially grown on the surface of the carbon wire to facilitate access to the surface of the metal oxide nanowire, thereby improving the performance of the gas sensor. Hierarchical nanostructures The present invention also provides a method for producing the same.

The shape, position, number and structure of the carbon wires can be freely controlled, and the metal oxide nanowires can be locally coated (grown) on or near the surface of the carbon wire, the production cost is reduced, and the productivity is remarkably increased And to provide a method of manufacturing a gas sensor capable of mass production.

A method (I) of manufacturing a gas sensor according to the present invention comprises the steps of: a) exposing and developing a first photoresist applied on a substrate to form a pair of photoresist electrodes spaced apart from each other and a photoresist Forming a wire; b) thermally decomposing a pair of photoresist electrodes and a photoresist wire to form a pair of integrated carbon electrodes and carbon wires connected to each other; c) forming a photoresist sacrificial layer over the pair of carbon electrodes and exposing the carbon wires by applying, exposing and developing a second photoresist on a substrate on which a pair of carbon electrodes and carbon wires are formed; d) forming a metal oxide seed on the carbon wire exposed by the photoresist sacrificial layer, and then removing the photoresist sacrificial layer; And e) growing a metal oxide seed to form a metal oxide nanowire on the carbon wire surface.

In the method (I) of manufacturing a gas sensor according to an embodiment of the present invention, the substrate may be a substrate having recessed grooves formed in a sensing region which is a region where carbon wires are formed.

In a method (I) of manufacturing a gas sensor according to an embodiment of the present invention, the step (a) comprises the steps of: a1) applying a first photoresist on a substrate on which an insulating film is formed, Forming an insulating film etching mask in which an insulating film region is exposed; a2) removing an insulating film region located in a sensing region using an insulating film etching mask and removing an insulating film etching mask; a3) forming a recessed groove by partially etching the substrate located in the sensing region using the insulating film from which the insulating film region located in the sensing region has been removed as a substrate etching mask; And a4) applying the first photoresist on the substrate with the recessed groove-formed substrate as a substrate.

In the method (I) of manufacturing a gas sensor according to an embodiment of the present invention, the growth of step (e) is performed by contacting the carbon wire with the metal oxide precursor, Metal oxide nanowires may be formed.

In a method (I) of manufacturing a gas sensor according to an embodiment of the present invention, the step a) comprises: applying a first photoresist on a substrate; Exposing a first photoresist using a photomask for forming an electrode having a shape corresponding to a pair of spaced apart electrodes; The first photoresist is re-exposed so that the pair of exposure areas exposed by the electrode forming photomask and the exposure area exposed by the wire forming photomask are connected to each other using a wire forming photomask having a wire shape step; And developing the re-exposed first photoresist to form a photoresist wire connecting the pair of spaced photoresist electrodes and the pair of photoresist electrodes to each other.

In the gas sensor manufacturing method (I) according to an embodiment of the present invention, the surface area of the first photoresist can be partially exposed upon re-exposure.

The method (II) for manufacturing a gas sensor according to the present invention comprises the steps of: i) exposing and developing a first photoresist applied on a substrate on which a recessed groove is formed to form a pair of photoresist electrodes spaced apart from each other by a recessed groove, Forming a photoresist wire over the groove and connecting the pair of photoresist electrodes to each other; j) pyrolyzing a pair of photoresist electrodes and a photoresist wire to form a pair of integrated carbon electrodes and carbon wires connected to each other; And k) forming a metal oxide nanowire on the carbon wire surface.

In a method (II) for manufacturing a gas sensor according to an embodiment of the present invention, step (k) comprises: k1) coating a metal oxide seed on the surface of the carbon wire; k2) metal oxide precursor and the carbon wire, and then growing the monocrystalline metal oxide nanowire from the metal oxide seed by the joule heat generated from the carbon wire.

In a method (II) for producing a gas sensor according to an embodiment of the present invention, i) comprises the steps of: applying a first photoresist on a substrate; Exposing a first photoresist using a photomask for forming an electrode having a shape corresponding to a pair of spaced apart electrodes; The first photoresist is re-exposed so that the pair of exposure areas exposed by the electrode forming photomask and the exposure area exposed by the wire forming photomask are connected to each other using a wire forming photomask having a wire shape step; And developing the re-exposed first photoresist to form a photoresist wire connecting the pair of spaced photoresist electrodes and the pair of photoresist electrodes to each other.

In the gas sensor manufacturing method (II) according to an embodiment of the present invention, the surface area of the first photoresist can be partially exposed upon re-exposure.

The gas sensor and the manufacturing method thereof according to the present invention have the following effects.

First, the suspended carbon conductive wire can be produced by a simple photoresist coating, a continuous exposure process, and a pyrolysis process in a low cost batch process.

Second, since the carbon wire and the carbon electrode are integrally formed at the same time, it is possible to complete the gas sensor structure which is electrically connected without any additional process for improving the physical and electrical contact between the carbon electrode and the carbon wire.

Third, the shape of the carbon wire is determined by the shape of the photomask in the exposure process, the amount of exposure energy, and the pyrolysis process. The distance between the carbon wire and the substrate is determined by the formation of the recess groove, the height of the photoresist, So that various types of hollow-portion-type carbon wire structures can be freely formed.

Fourth, since the carbon wire structure is formed due to the volume reduction through pyrolysis of the micro-unit photoresist, the nanostructure can be produced at low cost without expensive nano processing equipment.

Fifth, tensile stress is generated on the carbon wire due to the differential volume reduction caused by the height of the electrode during the pyrolysis process, and such tensile stress can prevent the deformation of the carbon wire caused by the external environment of the liquid phase.

Sixth, metal oxide nanowires, which are gas sensing materials, can grow metal oxide nanowires locally only on the surface of carbon wires as they are grown using the juxtaposition of carbon wires. In addition, since the size of the carbon wire is small, the electric energy of the carbon wire can easily raise the temperature of the carbon wire.

Seventh, the electrical connection between the two carbon electrodes supporting the carbon wire is formed only by the carbon wire and the metal oxide nanowire, so that the change in the electrical conductivity of the metal oxide nanowire due to the change in the gas concentration can be easily measured by the change in resistance between the two carbon electrodes . Eighth, since the metal oxide nanowires are grown on the surface of the carbon wire spaced apart from the substrate by a certain distance, the metal oxide nanowires are free from the influence of the substrate such as the temperature of the substrate, the contaminants and the stagnant layer, have.

Ninth, because the carbon wire is remote from the substrate, metal oxide nanowires can be grown on the entire surface of the carbon wire, and the metal oxide nanowires are grown radially on the carbon wire, The contact area is maximized and the sensitivity of the gas sensor can be increased.

In the tenth, since the metal oxide nanowires are selectively formed only in the carbon wire region, the accuracy, reproducibility and sensitivity of the gas sensor can be increased.

1 is a process diagram showing a method of manufacturing a gas sensor according to an embodiment of the present invention,
2 is another process drawing showing a method of manufacturing a gas sensor according to an embodiment of the present invention,
Figure 3 is another illustration of a method of manufacturing a gas sensor according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. The following drawings are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. Therefore, the present invention is not limited to the following drawings, but may be embodied in other forms, and the following drawings may be exaggerated in order to clarify the spirit of the present invention. Also, throughout the specification, like reference numerals designate like elements.

Hereinafter, the technical and scientific terms used herein will be understood by those skilled in the art without departing from the scope of the present invention. Descriptions of known functions and configurations that may be unnecessarily blurred are omitted.

FIG. 1 is a process diagram showing a method of manufacturing a gas sensor according to an embodiment of the present invention. FIG. 2 is another process drawing showing a method of manufacturing a gas sensor according to an embodiment of the present invention. Which is another example of a method of manufacturing a gas sensor according to an embodiment of the present invention. Hereinafter, a method of manufacturing a gas sensor according to the present invention will be described with reference to Figs.

A method (I) of manufacturing a gas sensor according to the present invention comprises the steps of: a) exposing and developing a first photoresist applied on a substrate to form a pair of photoresist electrodes spaced apart from each other and a photoresist Forming a wire; b) thermally decomposing a pair of photoresist electrodes and a photoresist wire to form a pair of integrated carbon electrodes and carbon wires connected to each other; c) forming a photoresist sacrificial layer over the pair of carbon electrodes and exposing the carbon wires by applying, exposing and developing a second photoresist on a substrate on which a pair of carbon electrodes and carbon wires are formed; d) forming a metal oxide seed on the carbon wire exposed by the photoresist sacrificial layer, and then removing the photoresist sacrificial layer; And e) growing a metal oxide seed to form a metal oxide nanowire on the carbon wire surface.

The substrate may serve as a support for physically supporting the carbon electrode and the carbon wire to be manufactured. Furthermore, the substrate may be a substrate having an insulating layer on at least a surface thereof so as not to affect a current or a voltage detected through the carbon electrode and the carbon wire.

Specifically, the substrate may be a wafer or a film (fim), and, in terms of physical properties, the substrate may be a rigid substrate or a flexible substrate. Crystallographically, the substrate may be monocrystalline, polycrystalline or amorphous, or it may be a mixed phase in which a crystalline phase and an amorphous phase are mixed. When the substrate is a laminated substrate in which two or more layers are laminated, each layer may be a monocrystalline, polycrystalline, amorphous or mixed phase independently of each other.

Materially, the substrate may be an inorganic substrate or an insulating organic substrate comprising a semiconductor. By way of non-limiting example, the substrate may be a semiconductor substrate, the semiconductor substrate being a quaternary semiconductor comprising silicon (Si), germanium (Ge) or silicon germanium (SiGe); Group 3-5 semiconductors including gallium arsenide (GaAs), indium phosphide (InP), or gallium phosphide (GaP); Group 2-6 semiconductors including cadmium sulfide (CdS) or zinc telluride (ZnTe); Group 4-6 semiconductors including lead sulfide (PbS); Or a laminated substrate in which two or more materials selected from these are laminated on each other. At this time, as described above, the semiconductor substrate may be a substrate having an insulating film on its surface. The insulating film may be formed by a known method such as thermal oxidation, vapor deposition, or the like. The insulating film may be at least one selected from the group consisting of silicon oxide, hafnium oxide, aluminum oxide, zirconium oxide, barium-titanium composite oxide, yttrium oxide, tungsten oxide, tantalum oxide, zinc oxide, titanium oxide, tin oxide, barium-zirconium composite oxide, But are not limited to, rides, zirconium silicates, hafnium silicates, mixtures thereof, and composites thereof. As a specific example, the semiconductor substrate may be a semiconductor substrate (including a wafer) such as a Si substrate; A semiconductor substrate (including a wafer) on which a semiconductor oxide layer such as a Si semiconductor substrate or a SOI (silicon on insulator) substrate having a surface oxide film formed thereon is laminated; And an SOI semiconductor substrate having a surface oxide film formed thereon.

However, when the inorganic substrate is an insulating material, it is needless to say that the inorganic substrate itself of the insulating material can be directly used. Nonlimiting examples of the insulating inorganic substrate include silicon oxide, hafnium oxide, aluminum oxide, zirconium oxide, barium-titanium composite oxide, yttrium oxide, tungsten oxide, tantalum oxide, zinc oxide, titanium oxide, tin oxide, barium-zirconium complex But are not limited to, oxides, silicon nitrides, silicon oxynitrides, zirconium silicates, hafnium silicates, mixtures thereof, and composites thereof.

The organic substrate may be a rigid or flexible organic substrate having an insulating property, and examples thereof include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide (PI), polycarbonate (PC) (PP), triacetylcellulose (TAC), polyethersulfone (PES), polydimethylsiloxane (PDMS), or a mixture thereof.

a) forming and exposing a first photoresist applied on a substrate to form a photoresist wire connecting a pair of photoresist electrodes spaced apart from each other and a pair of photoresist electrodes to each other, Applying a resist; Exposing a first photoresist using a photomask for forming an electrode having a shape corresponding to a pair of spaced apart electrodes; The first photoresist is re-exposed so that the pair of exposure areas exposed by the electrode forming photomask and the exposure area exposed by the wire forming photomask are connected to each other using a wire forming photomask having a wire shape step; And developing the re-exposed first photoresist to form a photoresist wire connecting the pair of spaced photoresist electrodes and the pair of photoresist electrodes to each other.

In the case where the substrate includes an insulating film, the first photoresist may be applied to the surface side where the insulating film is formed, and may be used as long as it is a material and a coating method of a photoresist conventionally used in the field of semiconductor device manufacturing. As a non-limiting example, the application of the first photoresist may be a method used for applying a photoresist in a conventional photolithography process, and a non-limiting example is spin coating. After application, drying (soft baking) of the applied photoresist layer may be performed, and optionally hard baking may be performed.

The first photoresist can be a high molecular substance whose resistance to chemicals is changed by light used in a conventional lithography process. The first photoresist can be exposed to light to be exposed to a negative type photoresist or light which is insoluble in chemicals, And a positive type photoresist that becomes soluble. As a specific example, the first photoresist may be a negative type photoresist such as SU-8.

The photomask for electrode formation may be a photomask which is formed in a size, structure and shape corresponding to the shape, structure and size of the designed electrode (a pair of electrodes). By exposing the first photoresist using a photomask for electrode formation, an exposure region can be formed in the first photoresist in a size, structure, and shape corresponding to the shape, structure, and size of the previously designed electrode. The light used for exposure may be light in the extreme ultraviolet to ultraviolet region, specifically ultraviolet light. A sufficient exposure can be performed so that the resistance to chemicals can be uniformly changed by light from the surface of the photoresist to the interface with the substrate at the time of exposure.

After exposure using an electrode-forming photomask, a pair of exposure areas exposed by a photomask for forming an electrode and an exposure exposed by a wire-forming photomask using a wire-forming photomask having a wire- A step of re-exposing the first photoresist so that the regions are connected to each other can be performed.

The first photoresist is exposed in the form of a perforation of the photomask by exposure using a photomask for forming an electrode, that is, a region exposed by a design corresponding to a pair of spaced apart electrodes (hereinafter, Exposure region) may be provided. The photomask for forming a wire may be a photomask formed in the form of a wire connecting exposure regions for a pair of electrodes to each other. Specifically, the perforation shape of the photomask for forming a wire may include a linear single wire, a single wire array, a mesh shape, or a honeycomb shape.

By re-exposing the first photoresist using a photomask for forming a wire, a wire-shaped exposure area connected to both ends of the exposure area for electrodes can be formed in the first photoresist together with a pair of electrode exposure areas have. In this case, it is needless to say that the wire-shaped exposure area may be a shape corresponding to the puncturing pattern of the wire-forming photomask.

The re-exposure may be light in the extreme ultraviolet to ultraviolet region, independently of the exposure using the photomask for forming an electrode, and may specifically be ultraviolet light. The light energy at the time of exposure can be adjusted so that only the surface layer of the first photoresist changes the resistance to the chemical by the light. That is, when the re-exposure is performed, the photoresist wire in the air floating type in which both ends are supported by the photoresist electrode during the development of the first photoresist can be manufactured by partially exposing the surface of the first photoresist only to a predetermined depth have.

A re-exposure using a photo mask for forming an electrode and a re-exposure using a photomask for forming a wire is performed, and then a developing step for removing the remaining portion of the photoresist except for the exposed portion may be performed. The development of the photoresist can be performed using a developer used in a conventional photolithography process.

By the development of the first photoresist, a photoresist wire connecting a pair of photoresist electrodes and a pair of photoresist electrodes spaced apart from each other may be formed on the substrate. At this time, the shape of the photoresist wire may include a linear single wire, a single wire array, a mesh shape, or a honeycomb shape, The uppermost surface of the resist electrode. In particular, the tops of the photoresist wires and the photoresist electrodes may be integral with each other, due to the formation of photoresist wires connecting the pair of photoresist electrodes to each other by exposure and re-exposure of the same first photoresist It is.

Thereafter, a pair of photoresist electrodes formed on the substrate and the photoresist wire are pyrolyzed to produce carbon electrodes and carbon wires. At this time, a pair of photoresist electrodes and a photoresist wire spaced apart from each other not only become carbonized through thermal decomposition, but also have a diameter of 100 nm to several 탆, a length of several 탆 to several hundred 탆, It can be several tens of 탆. Pyrolysis can be carried out in a vacuum or in an inert gas environment at a temperature of at least 800 ° C. A pair of photoresist electrodes and a photoresist wire are integrated so that the pair of photoresist electrodes and the photoresist wire are thermally decomposed by the thermal decomposition to form a pair of integrated carbon electrodes and carbon wires .

Thereafter, c) forming a photoresist sacrificial layer covering the pair of carbon electrodes and exposing the carbon wires by applying, exposing and developing a second photoresist on a substrate on which a pair of carbon electrodes and carbon wires are formed, .

In detail, a second photoresist layer can be formed by applying a second photoresist on a substrate on which a pair of carbon electrodes and a carbon wire are formed. The material and method of applying the second photoresist can be used as long as it is a material and a coating method of a photoresist commonly used in the field of semiconductor device manufacturing. As a non-limiting example, the application of the second photoresist may be a method used for applying a photoresist in a conventional photolithography process, and a non-limiting example is spin coating. After application, drying (soft baking) of the applied photoresist layer may be performed, and optionally hard baking may be performed.

The second photoresist can be a high molecular substance whose resistance to chemicals is changed by light used in a conventional lithography process. The second photoresist can be exposed to light to be exposed to a negative type photoresist or light which is insoluble in chemicals, And a positive type photoresist that becomes soluble. As a specific example, the second photoresist may be a positive type photoresist such as AZ.

The photomask (photomask for the sacrificial layer) used for exposure of the second photoresist is a sensing region which is a substrate region between two carbon electrodes which are mutually opposed to each other, that is, May be formed. At this time, as described later, the photoresist sacrificial layer prepared by exposing and developing the second photoresist is intended to confine the region where the metal oxide seed is formed to the carbon wire region, The length of the carbon wire may be equal to or less than the length of the carbon wire and may be equal to or similar to the length of the carbon wire based on the direction perpendicular to the spacing direction of the two carbon electrodes.

A photoresist sacrificial layer covering the pair of carbon electrodes and exposing the carbon wires may be formed by exposing and developing the second photoresist layer using the photomask for the sacrificial layer. At this time, the exposure of the second photoresist layer may be light in the extreme ultraviolet to ultraviolet region, and may be specifically ultraviolet light. The development of the second photoresist layer can be performed using a developer used in a conventional photolithography process.

Thereafter, a metal oxide seed is formed on the carbon wire exposed by the photoresist sacrificial layer, and then the photoresist sacrificial layer is removed. The step of forming a metal oxide seed on the carbon wire may be performed through physical vapor deposition or chemical vapor deposition. The physical vapor deposition or chemical vapor deposition may be performed by sputtering, magnetron-sputtering, E-beam evaporation, thermal evaporation, laser molecular beam epitaxy (L-MBE) But are not limited to, plasma enhanced deposition (PLD), vacuum deposition, atomic layer deposition (ALD), or plasma enhanced chemical vapor deposition (PECVD). In this case, it is of course possible to integrally coat a metal oxide seed on the surface of the carbon wire through vapor deposition, or to oxidize the metal thin film after the metal thin film is deposited, thereby forming a metal oxide seed.

The metal oxide of the metal oxide seed may be selected from one or more of zinc oxide (ZnO), copper oxide (CuO), indium oxide (In ₂ O ₃ ) and tin oxide (SnO ₂ ).

After the formation of the coating layer of the metal oxide seed on the carbon wire by using the deposition, the step of removing the photoresist sacrificial layer may be performed. The removal of the photoresist sacrificial layer may be performed by using a photoresist etching solution commonly used in the field of semiconductor device manufacturing or by a physical method such as lift-off.

Thereafter, e) a step of growing a metal oxide seed to form a metal oxide nanowire on the surface of the carbon wire may be performed.

When metal oxide nanowire formation, physical deposition or chemical deposition, is used, the metal oxide nanowire formation step and the metal oxide seed formation step may be performed through a single deposition process.

In the metal oxide nanowire forming step, the metal oxide precursor and the carbon wire are brought into contact with each other, and then the single crystal metal oxide nanowire can be produced from the seed by using the jelly generated from the carbon wire. That is, a metal oxide nanowire can be produced from a seed by flowing a current through a carbon electrode through a carbon electrode and using a jelly generated from a carbon wire.

A substrate provided with a carbon wire on which a coating layer of a metal oxide seed is formed on the side of the single crystal metal oxide nanowire formed from the metal oxide seed and the side of forming the metal oxide nanowire uniformly and uniformly around the surface of the carbon wire, A metal oxide nanowire as a gas sensing material is selectively grown on the surface of the carbon wire by applying a constant voltage to the two carbon electrodes after immersing the carbon nanotube in an autoclave containing a solution in which the metal oxide precursor is dissolved . Metal oxide materials of the nanowire may be the same as the metal oxide seed, the metal oxide a metal oxide nanowire is zinc oxide (ZnO), copper oxide (CuO), indium (In ₂ O ₃₎ and tin oxide (SnO ₂ ). ≪ / RTI > As a specific example, when the metal oxide nanowire is zinc oxide, the solution in which the metal oxide precursor is dissolved may be an aqueous solution containing Zinc nitride (Zn (NO ₃ ) ₂ ) and HMTA (hexamethylenetetramine).

Accordingly, the metal oxide nanowires whose electric conductivity changes according to the concentration of the gas are formed radially on the surface of the carbon wire. In this case, the change of the current value flowing by applying the voltage to the two carbon electrodes is measured, . Using zinc oxide nanowires, various gases such as C ₂ H ₅ OH, NO ₂ , H ₂ , H ₂ S, CO, O ₂ , and NH ₃ can be detected.

In the method of manufacturing a gas sensor according to an embodiment of the present invention, the substrate may be a substrate having recessed grooves formed in a sensing region which is a region where carbon wires are formed. Specifically, the step a) includes the steps of: a1) forming an insulating film etching mask on the substrate on which the insulating film is formed by applying the photoresist of the first aspect, exposing and developing the insulating film to expose the insulating film region located in the sensing region; a2) removing an insulating film region located in a sensing region using an insulating film etching mask and removing an insulating film etching mask; a3) forming a recessed groove by partially etching the substrate located in the sensing region using the insulating film from which the insulating film region located in the sensing region has been removed as a substrate etching mask; And a4) applying the first photoresist on the substrate with the recessed groove-formed substrate as a substrate. Here, as described above, it goes without saying that the substrate on which the insulating film is formed may be a semiconductor substrate having an insulating film formed thereon.

The material of the 1-1 photoresist and the method of applying the photoresist can be used as long as it is a material and a coating method of a photoresist commonly used in the field of semiconductor device production. As a non-limiting example, application of the 1-1 photoresist may include spin coating and the like. After application, drying (soft baking) of the applied photoresist layer may be performed, and optionally hard baking may be performed.

The first photoresist may be a polymer material whose resistance to chemicals is changed by light used in a conventional lithography process. The first photoresist may be exposed to light to be exposed to a negative type photoresist or light which is insoluble in chemicals, A positive type photoresist which is soluble in the positive type photoresist. As a specific example, the first photoresist may be a positive photoresist such as AZ.

The photomask used for exposure of the 1-1 photoresist includes a sensing region which is a substrate region between two carbon electrodes which are mutually opposed to each other, that is, a photomask having a perforation of a size and shape corresponding to the region where the carbon wire is located, Lt; / RTI > As an example, it may be the same or similar to the photomask used in manufacturing the photoresist sacrificial layer. The exposure of the first photoresist may be light in the extreme ultraviolet to ultraviolet region, specifically ultraviolet light. The development of the 1-1 photoresist layer can be performed using a developer used in a conventional photolithography process.

By exposure and development of the 1-1 photoresist, an area of the substrate where the carbon wires are provided, that is, an area of the insulating film corresponding to a region between two electrodes facing each other is exposed to the surface, 1, the exposed insulating film region can be removed using the photoresist as an insulating film etching mask. At this time, the removal of the insulating film may be performed by dry etching such as wet etching or plasma etching using an etching solution for selectively dissolving the material of the insulating film. As a non-limiting example, when the insulating film is a silicon oxide film, etching may be performed using an HF mixed aqueous solution. When the insulating film region corresponding to the sensing region is removed, the substrate (semiconductor substrate) can be selectively exposed to the surface only at the portion corresponding to the sensing region. Thereafter, the step of removing the 1-1 photoresist, partially etching the substrate located in the sensing region using the insulating film remaining on the substrate as a substrate etching mask, and forming a recessed groove may be performed. The etching of the substrate may be performed by dry etching, such as wet etching or plasma etching, using an etchant to selectively dissolve the substrate, and may be performed by wet etching in terms of isotropic etching. As a specific example, when the substrate is a Si substrate, wet etching may be performed using an alkaline etching solution containing nitrate. After the partial etching of the substrate is performed, a conventional cleaning step can be further performed, and the step of applying the first photoresist on the substrate of the step a) described above is carried out by using the recessed groove-formed substrate as the substrate .

The method (II) for manufacturing a gas sensor according to the present invention comprises the steps of: i) exposing and developing a first photoresist applied on a substrate on which a recessed groove is formed to form a pair of photoresist electrodes spaced apart from each other by a recessed groove, Forming a photoresist wire over the groove and connecting the pair of photoresist electrodes to each other; j) pyrolyzing a pair of photoresist electrodes and a photoresist wire to form a pair of integrated carbon electrodes and carbon wires connected to each other; And k) forming a metal oxide nanowire on the carbon wire surface.

The fabrication of the recessed grooves in step i) includes: a1) coating the first-type photoresist on the substrate on which the insulating film is formed, and then exposing and developing it to form an insulating film etching mask in which an insulating film region located in the sensing region is exposed ; a2) removing an insulating film region located in a sensing region using an insulating film etching mask and removing an insulating film etching mask; a3) forming a recessed groove by partially etching the substrate located in the sensing region using the insulating film from which the insulating film region located in the sensing region has been removed as a substrate etching mask; And a4) applying the first photoresist on the substrate with the recessed groove-formed substrate as a substrate, the detailed description thereof will be omitted.

forming a photoresist wire connecting the pair of photoresist electrodes of step i) to each other; And j) thermally decomposing a pair of photoresist electrodes and a photoresist wire to form a pair of carbon electrodes and a carbon wire integrally connected to each other, And b), the detailed description thereof will be omitted.

k) forming a metal oxide nanowire on the surface of the carbon wire; k1) coating the metal oxide seed on the surface of the carbon wire without forming the photoresist sacrifice layer; k2) metal oxide precursor and the carbon wire, and then growing the monocrystalline metal oxide nanowire from the metal oxide seed by the joule heat generated from the carbon wire.

Specifically, the metal oxide seed coating step of k1) immerses a substrate containing a pair of carbon electrodes and carbon wires in a solution capable of forming nanoparticles of a metal oxide to be grown, wherein the temperature of the solution is maintained for a predetermined time And a coating layer of a metal oxide nanoparticle (seed) can be formed on the surface of at least the carbon nanowire by heating. The metal oxide of the metal oxide seed may be selected from one or more of zinc oxide (ZnO), copper oxide (CuO), indium oxide (In ₂ O ₃ ) and tin oxide (SnO ₂ ). As a specific example, Zinc acetate (Zn (CH ₃ CO ₂ ) ₂ ) and methanol solution containing NaOH can be used to coat zinc oxide nanoparticles. However, if a photoresist sacrificial layer is used, the coating layer of the metal oxide seed may be performed through physical vapor deposition or chemical vapor deposition, as described above.

k2) metal oxide precursor and the carbon wire, and then growing the single-crystal metal oxide nanowire from the metal oxide seed by the joule heat generated from the carbon wire, e) growing the metal oxide seed as described above The step of forming the metal oxide nanowire on the surface of the carbon wire is the same or the same as the step of forming the metal oxide nanowire, so that the detailed description thereof will be omitted.

The present invention includes a gas sensor manufactured by the above-described manufacturing method.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, Those skilled in the art will recognize that many modifications and variations are possible in light of the above teachings.

Accordingly, the spirit of the present invention should not be construed as being limited to the embodiments described, and all of the equivalents or equivalents of the claims, as well as the following claims, belong to the scope of the present invention .

Claims (10)

a) exposing and developing a first photoresist applied on a substrate to form a pair of photoresist electrodes spaced apart from each other and a photoresist wire connecting the pair of photoresist electrodes to each other;
b) thermally decomposing the pair of photoresist electrodes and the photoresist wire to form a pair of integrated carbon electrodes and carbon wires connected to each other;
c) forming a photoresist sacrificial layer covering the pair of carbon electrodes and exposing the carbon wires by applying, exposing and developing a second photoresist on a substrate having a pair of carbon electrodes and carbon wires formed thereon;
d) forming a metal oxide seed on the carbon wire exposed by the photoresist sacrificial layer, and then removing the photoresist sacrificial layer; And
e) growing the metal oxide seed to form a metal oxide nanowire on the surface of the carbon wire;
And a gas sensor. The method according to claim 1,
Wherein the substrate is a substrate having a recessed groove formed in a sensing region which is an area where the carbon wires are formed. 3. The method of claim 2,
The step a)
a1) forming an insulating film etching mask on the substrate on which the insulating film is formed by coating the 1-1 photoresist, exposing and developing the insulating film to expose the insulating film region located in the sensing region;
a2) removing the insulating film region located in the sensing region using the insulating film etching mask and removing the insulating film etching mask;
a3) forming a recessed groove by partially etching the substrate located in the sensing region using the insulating film from which the insulating film region located in the sensing region is removed as a substrate etching mask; And
a4) applying the first photoresist on a substrate with a substrate having a recessed groove formed thereon as a substrate;
≪ / RTI > 4. The compound according to any one of claims 1 to 3,
Wherein the growth of step (e) comprises forming a metal oxide nanowire of monocrystalline form from the seed by a strip heat generated from the carbon wire after contacting the metal oxide precursor with the carbon wire. 4. The compound according to any one of claims 1 to 3,
The step a)
Applying a first photoresist on a substrate;
Exposing a first photoresist using a photomask for forming an electrode having a shape corresponding to a pair of spaced apart electrodes;
The first photoresist is re-exposed so that the pair of exposure areas exposed by the electrode forming photomask and the exposure area exposed by the wire forming photomask are connected to each other using a wire forming photomask having a wire shape step; And
Developing the re-exposed first photoresist to form a pair of photoresist electrodes spaced apart from each other and a photoresist wire connecting the pair of photoresist electrodes to each other;
And a gas sensor. 6. The method of claim 5,
Wherein during the re-exposure, the surface area of the first photoresist is partially exposed. (i) exposing and developing a first photoresist applied on a substrate on which a recessed groove is formed to form a pair of photoresist electrodes spaced apart from each other with the recessed groove therebetween, Forming a photoresist wire connecting resist electrodes to each other;
j) thermally decomposing the pair of photoresist electrodes and the photoresist wire to form a pair of integrated carbon electrodes and carbon wires connected to each other; And
k) forming a metal oxide nanowire on the carbon wire surface;
And a gas sensor. 8. The method of claim 7,
The step k)
k1) coating a surface of the carbon wire with a metal oxide seed;
k2) metal oxide precursor and the carbon wire, and growing a single-crystal metal oxide nanowire from the metal oxide seed by a joule generated in the carbon wire;
And a gas sensor. 8. The method of claim 7,
The step i)
Applying a first photoresist on a substrate;
Exposing a first photoresist using a photomask for forming an electrode having a shape corresponding to a pair of spaced apart electrodes;
The first photoresist is re-exposed so that the pair of exposure areas exposed by the electrode forming photomask and the exposure area exposed by the wire forming photomask are connected to each other using a wire forming photomask having a wire shape step; And
Developing the re-exposed first photoresist to form a pair of photoresist electrodes spaced apart from each other and a photoresist wire connecting the pair of photoresist electrodes to each other;
And a gas sensor. 10. The method of claim 9,
Wherein during the re-exposure, the surface area of the first photoresist is partially exposed.

Images