KR101776116B1 - A gas sensor having nanoporous structure and a method for manufacturing the same - Google Patents

Abstract

One embodiment of the present invention provides a method of manufacturing a gas sensor; and a gas sensor wherein a ratio of an opened porous where external gas is able to easily be introduced deep into a gas detection layer on the gas detection layer to increase efficiency. According to an embodiment of the present invention, the gas sensor having the nanoporous structure comprises: the gas detection layer formed on one surface of a substrate in a nanoporous structure through deposition of a deposition particle; and a signal treatment electrode installed in the substrate coming in contact with the gas detection layer.

Description

Technical Field [0001] The present invention relates to a gas sensor having a nanoporous structure and a method for manufacturing the same.

The present invention relates to a gas sensor having a nanoporous structure and a method of manufacturing the same, and more particularly to a gas sensor having a nanoporous structure, and more particularly, And a method of manufacturing the same.

In recent years, it is very important to develop ultra sensitive sensor materials that can preliminarily detect minute amounts of gas in the fields of environment, health, etc., and securing the source technology related thereto is becoming an important issue both domestically and internationally. For example, in the case of CO, which is a kind of reducing gas, inhalation thereof may cause death by interfering with oxygen transport by forming carboxy-hemoglobin in the blood and reducing the gas exchange ability of red blood cells, It is expected that a demand for a high sensitivity sensor capable of detecting a reducing gas such as CO as a substance requiring detection of a trace amount at a level of several hundred ppm is expected to increase.

A semiconductor gas sensor is a sensor that senses a gas to be sensed in such a manner as to measure a change in electrical conductivity that occurs when a semiconductor reacts with a gas. Particularly, by using a semiconductor gas sensor having a nanostructure, the reaction between the semiconductor and the gas can be maximized. This is because the nanostructure has a large specific surface area and the electron path is less than several tens nanometers (nm), compared with the case where the depletion layer on the surface of the gas sensor having the nanostructure is less than several tens nanometers (nm) If the nanostructure has a large porosity, the gas can be rapidly diffused to the inside.

Korean Patent No. 10-1372287 discloses a nanotube thin film gas sensor and a method of manufacturing the same, which are hereinafter referred to as a prior art 1, comprising: a first step of preparing a substrate on which electrodes are formed; A second step of depositing a metal thin film on the electrode of the substrate; A third step of anodizing the metal thin film to form a gas sensing film including metal oxide nanotubes; And a fourth step of etching the surface of the gas sensing film. An electrode formed on the substrate; And a gas sensing film formed on the electrode, wherein the gas sensing film includes a metal oxide nanotube formed by anodizing a metal thin film deposited on an electrode.

In the prior art 1, a metal thin film is formed on a substrate by vapor deposition, and then the metal thin film is anodized to form metal oxide nanotubes to form a nanostructured gas sensing film. And the efficiency of the gas sensor is reduced due to an increase in the ratio of the waste gas existing only in the interior of the gas sensor.

In addition, the above-mentioned prior art 1 has a second problem that it can not perform high sensitivity sensing due to an increase in specific surface area because it generates a nanoporous structure by anodic oxidation and surface time.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not intended to limit the invention to the precise form disclosed. There will be.

According to an aspect of the present invention, there is provided a plasma display panel comprising: a substrate; A gas sensing layer formed on one surface of the substrate with a nanoporous structure through deposition of the deposition particles; And a signal processing electrode provided on the substrate, the signal processing electrode contacting the gas detection layer.

In an embodiment of the present invention, the specific surface area value of the gas sensing layer may be 5 to 300 m ² / g.

In an embodiment of the present invention, the density ratio of the gas sensing layer (in terms of bulk) may be 0.01 to 40%.

In the embodiment of the present invention, the inside of the gas sensing layer may have a density gradient in which the relative density decreases or increases from one direction to the other.

In an embodiment of the present invention, the gas sensing layer may be formed by thermal evaporation using a baffle.

In an embodiment of the present invention, the baffle may have a function of suppressing radiation, convection, and conduction generated by the heat source of the thermal vapor deposition.

In an embodiment of the present invention, the baffle may be formed with a perforated hole for moving the deposition particles.

In an embodiment of the present invention, the baffle may be formed of one or more materials selected from the group consisting of a metal, an alloy, and a ceramic material.

In an embodiment of the present invention, the process pressure of the deposition may be 0.01 to 10 Torr.

In the embodiment of the present invention, the gas sensing layer may be formed of a metal or a metal oxide, or may be formed of a mixture of a metal and a metal oxide.

In an embodiment of the present invention, the metal oxide may be at least one selected from the group consisting of Sn, Ni, Cu, Ti, V, Cr, Mn, (Fe), cobalt (Co), zinc (Zn), molybdenum (Mo), tungsten (W), silver (Ag), gold (Au), platinum (Pt), iridium (Ir), ruthenium Li, Al, Al, Sb, Bi, Mg, Si, In, Pb and Pd. It can be more than one material.

In an embodiment of the present invention, the metal is at least one selected from the group consisting of Au, Ag, Pd, Al, Cu, Cr, Fe, ), Mn, Ni, Ti, Zn, Pb, V, Cob, Er, Ca, ), Samarium (Sm), scandium (Sc), terbium (Tb), molybdenum (Mo), and platinum (Pt).

In an embodiment of the present invention, the substrate may be formed of metal, ceramic, plastic, or paper.

In an embodiment of the present invention, when a current is applied to the heater electrode and the signal processing electrode provided on one surface of the substrate, the temperature of the substrate may rise.

In an embodiment of the present invention, the gas sensing layer is a network including a mesopore having a diameter of 1.0 to 100 nanometers (nm) and a macropore having a diameter of 0.5 micrometers or more .

According to an aspect of the present invention, there is provided a method of manufacturing a plasma display panel, including: (i) providing a substrate provided with a signal processing electrode and a heater electrode; (Ii) fixing the substrate to a deposition chamber and bringing the inside of the deposition chamber into a vacuum state; (Iii) injecting a process gas into the deposition chamber in a vacuum state to form a process pressure; (Iv) setting the temperature of the substrate to 50 DEG C or lower; (V) in the deposition chamber, raising the temperature of the heat source containing the deposition material to form the vapor of the deposition material; And (vi) depositing the deposited particles on the substrate in the step (v) to form a gas sensing layer. The present invention also provides a method of manufacturing a gas sensor having a nanoporous structure, do.

In the embodiment of the present invention, the step (ii) may further include the step of providing a baffle at a predetermined position between the substrate and the evaporation source.

In the embodiment of the present invention, in the step (v), a shape plate may be provided at a predetermined position between the substrate and the evaporation source, and the gas detection layer may be formed only on a part of the substrate, .

In an embodiment of the present invention, the step (vi) may further include a step of heat-treating the gas sensing layer, the substrate, or the signal processing electrode at 200 to 1000 degrees Celsius.

The present invention forms a nanoporous structure while growing a nanostructure by controlling the deposition rate and the like to form a gas detection layer, so that an open gas can be easily introduced into the gas detection layer, The ratio of the pores increases, and the first effect that the efficiency of the gas sensor increases is obtained.

In the present invention, since the gas sensing layer is formed in such a manner that each of the deposited particles is sequentially deposited for a predetermined time and the nanostructure is grown, the specific surface area of such a nanoporous structure is largely formed, The second effect is obtained.

It should be understood that the effects of the present invention are not limited to the above effects and include all effects that can be deduced from the detailed description of the present invention or the configuration of the invention described in the claims.

1 is a cross-sectional view of a gas sensor according to an embodiment of the present invention.
2 is a schematic diagram of a density gradient inside a gas sensing layer according to an embodiment of the present invention.
3 is a schematic view of the inside of the deposition chamber in the production of the gas detection layer according to the embodiment of the present invention.
4 is a top view of a baffle according to an embodiment of the present invention.
FIG. 5 is a graph showing the density change of the gas detection layer according to the process pressure control in the deposition chamber according to the embodiment of the present invention.
FIG. 6 is a graph showing the sensing performed on benzene using a gas sensor according to an embodiment of the present invention. FIG.
FIG. 7 is a graph showing a result of sensing for ethanol using a gas sensor according to an embodiment of the present invention. FIG.
FIG. 8 is a graph showing a result of sensing for carbon monoxide (CO) using a gas sensor according to an embodiment of the present invention.
9 is an SEM image of the gas detection layer according to [Example 1] and [Example 2] of the present invention.
10 is an SEM image of the gas detection layer according to [Example 3] and [Example 4] of the present invention.
11 is an SEM image of the gas detection layer according to [Example 5] and [Example 6] of the present invention.
12 is an SEM image of a gas detection layer according to [Example 1] and [Example 2] of the present invention taken after heat treatment at 700 deg. C for 1 hour.
13 is an SEM image of the gas detection layer according to [Example 3] and [Example 4] of the present invention taken after heat treatment at 700 deg. C for 1 hour.
Fig. 14 is a SEM image of a gas detecting layer according to [Example 5] and [Example 6] of the present invention taken after heat treatment at 700 deg. C for 1 hour.
Fig. 15 is a graph showing the relationship between the gas detection layer according to Example 1, Example 2, Example 3, Example 4, Example 5 and Example 6 of the present invention before heat treatment And a specific surface area measured after heat treatment at 700 ° C for 1 hour.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, when a part is referred to as being "connected" (connected, connected, coupled) with another part, it is not only the case where it is "directly connected" "Is included. Also, when an element is referred to as "comprising ", it means that it can include other elements, not excluding other elements unless specifically stated otherwise.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, the terms "comprises" or "having" and the like refer to the presence of stated features, integers, steps, operations, elements, components, or combinations thereof, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a cross-sectional view of a gas sensor according to an embodiment of the present invention.

As shown in FIG. 1, the gas sensor having the nanoporous structure of the present invention includes a substrate 20; A gas sensing layer (10) formed on the surface of the substrate (20) through deposition of the deposition particles in a nanoporous structure; And a signal processing electrode (30) provided on the substrate (20) and in contact with the gas detection layer (10).

At this time, a current can be applied to the gas sensing layer 10 and the signal processing electrode 30 to perform gas sensing. Specifically, the resistance value of the gas sensing layer 10 is compared with the resistance value of the gas sensing layer 10 when a current is applied in a state in which the gas is in contact with the resistance value of the gas sensing layer 10 when a current is applied in a state where the gas is not in contact, It is possible to judge whether the gas is sensed by changing the resistance value. That is, it is possible to compare the resistance values before and after the penetration of the gas molecules into the nanoporous structure forming the gas detection layer 10, and to sense the difference in the resistance value for each situation.

The gas detection layer 10 may be formed by thermal evaporation using a baffle 51.

The baffle 51 may have a function of suppressing radiation, convection, and conduction of heat generated by the heat source for thermal vapor deposition.

Details of the baffle 51 will be described later.

The specific surface area value of the gas detection layer 10 may be 5 to 300 m ² / g.

If the specific surface area of the gas sensing layer 10 is less than 5 m < ² > / g, the nanoporous structural structure of the gas sensing layer 10 becomes dense and the gas molecules are introduced into the nanoporous structure of the gas sensing layer 10 The ratio to the case of not penetrating deeply is increased, so that the sensitivity and efficiency of the gas sensor may be deteriorated. If the specific surface area of the gas sensing layer 10 is more than 300 m ² / g, the stable bonding force between nanoparticles of the nanoporous structure of the gas sensing layer 10 can not be ensured and durability can be reduced, The area where the nanoparticles aggregate is increased as compared with the surface area, and the movement path of the gas molecules is limited, so that the sensitivity and efficiency of the gas sensor may be deteriorated.

The density ratio (in terms of bulk) of the gas detection layer 10 may be 0.01 to 40%.

If the density ratio of the gas detection layer 10 is less than 0.01%, the performance of the gas sensor related to the adhesion property between the gas detection layer 10 and the substrate 20 may be deteriorated. If the density ratio of the gas sensing layer 10 is more than 40%, the specific surface area value of the gas sensing layer 10 is drastically lowered, and the nanoporous structural structure of the gas sensing layer 10 becomes dense, The sensitivity and efficiency of the gas sensor may deteriorate because the ratio to the case of not penetrating deeply into the nanoporous structure of the gas detection layer 10 is increased.

By controlling the specific surface area value of the gas detection layer 10 or the density ratio of the gas detection layer 10 to produce the gas detection layer 10 suitable for the type of gas, It can be optimized.

2 is a schematic diagram of a density gradient inside the gas sensing layer 10 according to an embodiment of the present invention. 2 (a) shows a state in which a density gradient is formed from one side of the gas sensing layer 10 in contact with the substrate 20 to the other side in the outward direction, and Fig. 2 (b) And a state in which a density gradient is formed from one side of the gas detection layer 10 in contact with the substrate 20 to the other side in the outward direction.

The inside of the gas sensing layer 10 may have a density gradient in which the relative density decreases or increases from one direction to the other.

This can be achieved by adjusting at least one of the type of process gas inside the deposition chamber 52, the process pressure, the temperature of the substrate 20, the distance between the substrate 20 and the evaporation source 53, And varying the energy and size of the deposited particles.

Here, the density is the distribution density of the nanoporous structure provided in the gas detection layer 10, and quantitatively, it can be represented by the density of the bulk material and the relative density of the nanoporous structure.

If the porosity is large, the relative density is low, so that the contact area between the substrate 20 and the gas sensing layer 10 is reduced, and a relatively weak bonding relationship is formed, and there is a high possibility that mutual peeling or separation occurs . Such a configuration can be used to improve the sensitivity by increasing the surface area by use of the gas detection layer 10. [

When the porosity is low, the relative density is high and the contact area between the substrate 20 and the gas detection layer 10 is increased, so that a relatively strong coupling relation is formed and the possibility of mutual peeling is small The cohesive force can be increased. This configuration can be used for improving the durability of the gas sensor related to the bonding force between the substrate 20 and the gas sensing layer 10. [

The gas detection layer 10 may be formed of a metal or a metal oxide, or may be formed of a mixture of a metal and a metal oxide.

The metal oxide may be at least one selected from the group consisting of Sn, Ni, Cu, Ti, V, Cr, Mn, Fe, (Ag), gold (Au), platinum (Pt), iridium (Ir), ruthenium (Ru), lithium (Li), aluminum (Al), zinc (Zn), molybdenum (Mo), tungsten , An oxide of antimony (Sb), bismuth (Bi), magnesium (Mg), silicon (Si), indium (In), lead (Pb) and palladium (Pd).

The metal may be at least one selected from the group consisting of Au, Ag, Pd, Al, Cu, Cr, Fe, Mg, (Ni), Ti, Zn, Pb, V, Co, Er, Ca, May be at least one material selected from the group consisting of scandium (Sc), terbium (Tb), molybdenum (Mo), and platinum (Pt).

The substrate 20 may be formed of metal, ceramic, plastic, or paper.

Specifically, the substrate 20 can be made of a single metal such as iron (Fe), nickel (Ni), zinc (Zn), copper (Cu), aluminum (Al)

Alternatively, the substrate 20 may be made of ceramics such as alumina or silicon.

Alternatively, the substrate 20 may be made of plastic or paper such as polyimide (PI), polyethylene phthalate (PET), poly (oxyethyleneoxycarbonylnaphthalene-2,6-diylcarbonyl), or polyether sulfone (PES).

The temperature of the substrate 20 can be raised when a current is applied to the heater electrode 40 and the signal processing electrode 30 provided on one surface of the substrate 20. [

The heater electrode 40 may be attached to the surface of the substrate 20 corresponding to the surface on which the signal processing electrode 30 is provided as shown in FIG. 1, but the present invention is not limited thereto.

In a gas sensor using MEMS (Micro Electro Mechanical Systems), it may be particularly important to reduce the amount of power injected into the heater electrode 40 in order to raise the temperature of the gas sensing layer 10. Therefore, in order to minimize the heat radiated to the substrate 20, after a portion of the substrate 20 is scraped off and an insulating layer (SiOx or SiNx) is formed, a gas sensing layer 10, The heater electrode 30 and the heater electrode 40 can be formed.

When the temperature of the substrate 20 rises, the temperature of the gas detection layer 10 formed in contact with the substrate 20 is raised, and gas molecules penetrating into the nanoporous structure of the gas detection layer 10 are supplied with thermal energy Can be volatilized. Accordingly, the gas sensing layer 10 can improve the sensitivity or shorten the recovery time to the state before the gas sensing, and can increase the efficiency of the gas sensor.

The gas sensing layer 10 may comprise a network that simultaneously includes a mesopore having a diameter of 1.0 to 100 nanometers and a macropore having a diameter of 0.5 micrometers or more.

Hereinafter, a method of manufacturing a gas sensor having a nanoporous structure will be described.

FIG. 3 is a schematic view of the inside of the deposition chamber 52 when the gas detection layer 10 is manufactured according to the embodiment of the present invention, and FIG. 4 is a plan view of the baffle 51 according to the embodiment of the present invention.

3, the apparatus for manufacturing a gas sensor having a nanoporous structure includes a deposition chamber 52 capable of being in a vacuum state, an evaporation source 53 for supplying thermal energy to the deposition material, A baffle 51 positioned between the evaporation source 53 and the substrate 20, and an exhaust port 55. [

In the first step, the substrate 20 provided with the signal processing electrode 30 and the heater electrode 40 can be provided.

Here, the signal processing electrode 30 or the heater electrode 40 may be formed on the substrate 20 by a vacuum deposition method such as physical vapor deposition (PVD) or a printing method such as inkjet or screen printing. In addition, a photolithograppy process may be further used to form the pattern.

In the second step, the substrate 20 may be fixed to the deposition chamber 52 and the inside of the deposition chamber 52 may be evacuated.

Here, the method may further include the step of providing a baffle 51 at a predetermined position between the substrate 20 and the evaporation source 53.

Since the deposition particles are sequentially deposited on the substrate 20 by a predetermined path by the baffle 51, a nanoporous structure is formed by a method in which the nanostructure is grown to form the gas sensing layer 10 of the present invention .

As shown in FIG. 4, the baffle 51 may be formed with perforated holes for moving the deposition particles. The deposition particles moving through the holes drilled at regular intervals to the surface of the substrate 20 can be deposited while forming a uniform thickness on the surface of the substrate 20 and uniformly distributed.

The holes may be in the form of a circle or a polygon, and the shape of the circle may be preferred for uniformity in position.

The baffle 51 may be formed of a plurality of layers. A plurality of baffles 51 may be provided in the deposition chamber 52. Thus, the flow of the deposition particles deposited on the substrate 20 can be controlled.

The baffle 51 may be formed of one or more materials selected from the group consisting of a metal, an alloy, and a ceramic material.

Specifically, the baffle 51 is made of a metal such as iron (Fe), titanium (Ti), molybdenum (Mo), cobalt (Co), nickel (Ni), tungsten (W), beryllium (Be) And may be formed of at least one metal selected from the group consisting of Sn, Si, Cr, Zn, Cu, and Al. Also, the baffle 51 may be formed of one or more ceramic materials selected from the group consisting of alumina, silicon nitride, silicon carbide, and zirconia.

In the third step, a process gas may be injected into the vacuum chamber 52 to form process pressure.

The process pressure of the deposition may be 0.01 to 10 Torr.

If the process pressure is less than 0.01 Torr, the thin film may be densely formed and pores may not be formed in the thin film. If the process pressure is more than 10 Torr, it may be difficult to maintain the uniformity of the nanoporous structure of the gas detection layer 10 . Because under the process pressure exceeding 10 Torr, the deposited particles may experience excessive collision until reaching the substrate 20. [

As the process gas, at least one gas selected from among argon (Ar), nitrogen (N ₂ ), helium (He), neon (Ne), krypton (Kr), xenon (Xe) and radon But it is not limited thereto as long as it is a gas that does not react with the deposition particles. In particular, when the gas sensing layer 10 to be formed is an oxide, oxygen may be used in addition to the above-mentioned inert gas for securing stability of the oxidation state. In this case, oxygen may replace some or all of the inert gas , The mixing ratio of oxygen and the inert gas can be experimentally determined to uniformly form the mesopore structure to be described later.

This kind of process gas can also be one of the process parameters for forming the density gradient. The gas molecule particle size differs depending on the kind of the process gas, so that the probability that the particles collide with each other and the energy change after the collision may differ, and the thermal conductivity of the process gas also differs. In addition, when oxygen or the like is used as the process gas, the reaction with the raw material may be considered.

In the fourth step, the temperature of the substrate 20 can be set to 50 DEG C or less.

In order to improve the uniformity of the gas sensing layer 10 formed on the substrate 20, the temperature of the substrate 20 needs to be kept uniform. If the temperature of the substrate 20 is higher than 50 ° C, it will provide more energy than necessary for the material to be deposited, resulting in reduced open pores, increased particle size, and an excessively dense thin film formed relative to the porous nanostructure to be implemented There is a possibility.

Here, the substrate 20 is firmly fixed to the cooling part 54, and deposition can be performed.

The cooling section 54 cools the substrate 20 by the cooling water being supplied and discharged, and the entire area of the substrate 20 can be maintained at a uniform temperature.

In the fifth step, in the deposition chamber 52, the temperature of the heat source 53 containing the deposition material can be raised to form the vapor of the deposition material.

At this time, a shape plate (not shown) is provided at a predetermined position between the substrate 20 and the evaporation source 53 so that only the part of the substrate 20 is covered with the gas detection layer (10) can be formed. Accordingly, gas detection layers 10 having various shapes can be formed.

An exhaust port 55 may be provided on one surface of the deposition chamber 52 so that the flow of the deposition particles is formed in the direction of one surface of the deposition chamber 52 from the evaporation source 53.

In the sixth stage, the resultant deposited particles of the fifth stage may be deposited on the substrate 20 to form the gas sensing layer 10.

Here, the deposition rate of the deposited particles may be 0.01 to 10 micrometers / minute (mu m / min). If the deposition rate of the deposited particles is less than 0.01 micrometers / minute (mu m / min), the productivity is too low. If it exceeds 10 micrometers / minute (mu m / min) And the formed nanostructure may be damaged due to heat.

After the sixth step, the gas sensing layer 10, the substrate 20, or the signal processing electrode 30 may be further subjected to heat treatment at 200 to 1000 degrees Celsius.

The heat treatment may be performed to improve the durability of the gas detection layer 10, the substrate 20, or the signal processing electrode 30. [

If the heat treatment temperature is less than 200 degrees Celsius, the heat treatment effect does not reach the reference value, and the durability improvement of the gas detection layer 10, the substrate 20, or the signal processing electrode 30 may be low. When the heat treatment temperature is higher than 1000 degrees Celsius, the nanoporous nanoporous structure forming the gas sensing layer 10 increases in size and the pore ratio is lowered, so that the efficiency of the gas sensor can be reduced.

Hereinafter, embodiments and experimental examples of a gas sensor having a nanoporous structure according to the present invention will be described.

[Example 1]

A signal processing electrode 30 formed of an alloy of platinum (Pt) and titanium (Ti) is formed on a substrate 20 formed of a silicon nitride film (SiNx) / silicon (CuSi) Tin dioxide (SnO ₂ ) was chosen as the material for the formation. The deposition chamber 52 is provided with a baffle 51 and a shape plate. One surface of the substrate 20 on which the signal processing electrode 30 is formed faces toward the evaporation source 53 and the other surface of the substrate 20 corresponding to one surface of the substrate 20 contacts the cooling unit 54 20) were installed. Thereafter, the process pressure was set to 0.05 Torr, argon (Ar) gas was injected as the process gas, and the deposition was performed at the temperature of the cooling section 54 at 3 캜. The deposition time was 50 minutes. Thereby, the gas sensing layer 10 having the nanoporous structure, which is in contact with the substrate 20 and the signal processing electrode 30, is formed. Thereafter, heat treatment was performed for 1 hour under an air atmosphere of 700 degrees.

[Example 2]

The process pressure in the deposition chamber 52 was set at 0.2 Torr. Then, the remaining conditions were set to be the same as those in [Example 1].

[Example 3]

The process pressure in the deposition chamber 52 was set at 0.5 Torr. Then, the remaining conditions were set to be the same as those in [Example 1].

[Example 4]

The process pressure in the deposition chamber 52 was set to 1 Torr. Then, the remaining conditions were set to be the same as those in [Example 1].

[Example 5]

The process pressure in the deposition chamber 52 was set at 2 Torr. Then, the remaining conditions were set to be the same as those in [Example 1].

[Example 6]

The process pressure in the deposition chamber 52 was set at 5 Torr. Then, the remaining conditions were set to be the same as those in [Example 1].

[Experimental Example 1-1]

A gas sensor of Example 1, a gas sensor of Example 2, a gas sensor of Example 3, and a gas sensor of Example 4 were provided. Thereafter, the gas sensor of Example 1, the gas sensor of Example 2, the gas sensor of Example 3, the gas sensor of Example 4, the Example 5, and the Example 6, Was raised to 300 DEG C, and gas sensing was performed on 20 ppm of benzene.

[Experimental Example 1-2]

A gas sensor of Example 1, a gas sensor of Example 2, a gas sensor of Example 3, and a gas sensor of Example 4 were provided. Thereafter, the gas sensor of Example 1, the gas sensor of Example 2, the gas sensor of Example 3, and the gas sensor of Example 4, Example 5, and Example 6, Was raised to 400 DEG C, and gas sensing was performed on 20 ppm of benzene.

[Experimental Example 1-3]

A gas sensor of Example 1, a gas sensor of Example 2, a gas sensor of Example 3, and a gas sensor of Example 4 were provided. Thereafter, the gas sensor of Example 1, the gas sensor of Example 2, the gas sensor of Example 3, and the gas sensor of Example 4, Example 5, and Example 6, Was raised to 500 DEG C, and gas sensing was performed on 20 ppm of benzene.

[Experimental Example 2-1]

A gas sensor of Example 1, a gas sensor of Example 2, a gas sensor of Example 3, and a gas sensor of Example 4 were provided. Thereafter, the gas sensor of Example 1, the gas sensor of Example 2, the gas sensor of Example 3, and the gas sensor of Example 4, Example 5, and Example 6, Was raised to 300 DEG C, and gas sensing was performed on 20 ppm of ethanol (Ethanol).

[Experimental Example 2-2]

A gas sensor of Example 1, a gas sensor of Example 2, a gas sensor of Example 3, and a gas sensor of Example 4 were provided. Thereafter, the gas sensor of Example 1, the gas sensor of Example 2, the gas sensor of Example 3, and the gas sensor of Example 4, Example 5, and Example 6, Was raised to 400 DEG C, and gas sensing was performed on 20 ppm of ethanol (Ethanol).

[Experimental Example 2-3]

A gas sensor of Example 1, a gas sensor of Example 2, a gas sensor of Example 3, and a gas sensor of Example 4 were provided. Thereafter, the gas sensor of Example 1, the gas sensor of Example 2, the gas sensor of Example 3, and the gas sensor of Example 4, Example 5, and Example 6, Was raised to 500 DEG C, and gas sensing was performed on 20 ppm of ethanol (Ethanol).

[Experimental Example 3-1]

A gas sensor of Example 1, a gas sensor of Example 2, a gas sensor of Example 3, and a gas sensor of Example 4 were provided. Thereafter, the temperature of the gas sensor of Example 1, the gas sensor of Example 2, the gas sensor of Example 3, and the gas sensor of Example 4 was raised to 300 ° C, and 20 ppm of carbon monoxide ( CO) were subjected to gas sensing.

[Experimental Example 3-2]

A gas sensor of Example 1, a gas sensor of Example 2, a gas sensor of Example 3, and a gas sensor of Example 4 were provided. Thereafter, the temperature of the gas sensor of Example 1, the gas sensor of Example 2, the gas sensor of Example 3, and the gas sensor of Example 4 was raised to 400 ° C, and 20 ppm of carbon monoxide ( CO) were subjected to gas sensing.

[Experimental Example 3-3]

A gas sensor of Example 1, a gas sensor of Example 2, a gas sensor of Example 3, and a gas sensor of Example 4 were provided. Thereafter, the temperature of the gas sensor of Example 1, the gas sensor of Example 2, the gas sensor of Example 3, and the gas sensor of Example 4 was raised to 500 ° C, and 20 ppm of carbon monoxide CO) were subjected to gas sensing.

5 is a graph showing the density change of the gas sensing layer 10 according to the process pressure control in the deposition chamber 52 according to the embodiment of the present invention.

5, the density means the density of the gas sensing layer 10, and the bulk density means the density for the same volume when the same material is in a normal state, and the density ratio is the density / bulk Density.

As shown in FIG. 5, it can be seen that the gas detection layer 10 is mostly formed of pores in each of the embodiments. As the process pressure in the process conditions increases, the density ratio decreases and the density of the gas sensing layer 10 decreases.

FIG. 6 is a graph showing a result of sensing for benzene using a gas sensor according to an embodiment of the present invention, and FIG. FIG. 8 is a graph showing a result of sensing for carbon monoxide (CO) using a gas sensor according to an embodiment of the present invention. FIG.

In each graph, Ra means the resistance of the gas detection layer 10 in the air state, and Rg means the resistance of the gas detection layer 10 after the gas is introduced. Sensitivity of the sensing with respect to the gas can be expressed by Ra / Rg.

6A is a graph showing the sensitivity of sensing for benzene and FIG. 6B is a graph showing the response time for benzene. FIG.

6A is a graph of [Experimental Example 1-1], and a graph of 400 DEG C of FIG. 6A is a graph of [Experimental Example 1-2] The graph of a) at 500 ° C is a graph of [Experimental Example 1-3].

As shown in FIG. 6, as the process pressure in the process conditions increases, the sensitivity of the sensing for benzene generally increases. And, inversely, it was confirmed that as the process pressure increases in the process conditions, the response time of the sensing for benzene decreases.

This is because, as the process pressure is increased, the increase of the specific surface area and the increase of the pore ratio are so large that the ratio of open pores that gas can easily enter deeply into the gas detection layer 10 increases, ) And the response time of the sensing (Response Time) decreases. However, if the process pressure is increased to 2 Torr or more, the ratio of the open pores is almost constant, but the specific surface area is decreased, and the sensitivity of the sensing is decreased and the response time of the sensing is increased .

FIG. 7A is a graph showing sensitivity of sensing with respect to ethanol, and FIG. 7B is a graph showing response time with respect to ethanol.

7A is a graph of [Experimental Example 2-1], and a graph of 400 DEG C of FIG. 7A is a graph of [Experimental Example 2-2] The graph of 500 ° C in a) is a graph of [Experimental Example 2-3].

As shown in FIG. 7, it can be seen that as the process pressure increases in the process conditions, the sensitivity of the sensing to ethanol increases substantially. And, inversely, it was confirmed that as the process pressure increases in process conditions, the response time of sensing for ethanol decreases.

This is because, as the process pressure is increased, the increase of the specific surface area and the increase of the pore ratio are so large that the ratio of open pores that gas can easily enter deeply into the gas detection layer 10 increases, ) And the response time of the sensing (Response Time) decreases. However, if the process pressure is higher than 2 Torr, the ratio of the open pores is almost constant, but the specific surface area is decreased and the sensitivity of the sensing is decreased and the response time of the sensing is increased.

FIG. 8A is a graph showing sensitivity of sensing for carbon monoxide (CO), and FIG. 8B is a graph showing a response time for carbon monoxide (CO).

8A is a graph of [Experimental Example 3-1], and a graph of 400 DEG C of FIG. 8A is a graph of [Experimental Example 3-2] The graph of a) at 500 ° C is a graph of [Experimental Example 3-3].

As shown in FIG. 8, it can be seen that the sensitivity of sensing for carbon monoxide (CO) generally increases with increasing process pressure in process conditions. Also, it was confirmed that the response time of the sensing for carbon monoxide (CO) changes when the process pressure is increased in the process conditions. This shows a tendency different from the graph for benzene or ethanol, so that sensitivity and response time can be appropriately selected depending on the use of the gas sensor for carbon monoxide (CO).

This is because, as the process pressure is increased, the increase of the specific surface area and the increase of the pore ratio are so large that the ratio of open pores that gas can easily enter deeply into the gas detection layer 10 increases, ) And the response time of the sensing (Response Time) decreases.

6, FIG. 7, and FIG. 8, it is possible to control the sensitivity and the response time of the gas sensor by controlling the process pressure, the heat treatment temperature, and the like, , The gas sensor can be manufactured by selecting an appropriate sensitivity or reaction time.

Fig. 9 is an SEM image of the gas detection layer 10 according to [Example 1] and [Example 2] of the present invention, and Fig. 10 is a SEM image of the gas according to [Example 3] and [Example 4] 11 is an SEM image of the gas sensing layer 10 according to [Example 5] and [Example 6] of the present invention. (Example 1), Fig. 9 (b): Example 2, Fig. 10 (a): [Example 3], Fig. 10 (b) 4], FIG. 11 (a): [Example 5], and FIG. 11 (b): [Example 6]

As shown in FIGS. 9, 10 and 11, it can be seen that as the deposition process pressure increases, the ratio of pores increases in the nanoporous structure of the gas sensing layer 10 formed by vapor deposition.

FIG. 12 is an SEM image taken after heat treatment of the gas detection layer 10 according to [Example 1] and [Example 2] of the present invention at 700 degrees for 1 hour, and FIG. 13 is a SEM image 14 is a SEM image of the gas sensing layer 10 according to the first embodiment of the present invention and the gas sensing layer 10 according to the third embodiment of the present invention after heat treatment at 700 degrees for 1 hour. Is a SEM image of the gas sensing layer 10 after heat treatment at 700 ° C. for 1 hour. (Example 1), Fig. 12 (b): Example 2, Fig. 13 (a): [Example 3], Fig. 13 (b) 4], FIG. 14 (a): [Example 5], FIG. 14 (b): [Example 6]

12, 13 and 14, it can be seen that as the deposition process pressure increases, the ratio of pores in the nanoporous structure of the gas sensing layer 10 formed by the deposition increases. The bond between the deposited particles is clearly shown by the heat treatment, and the durability of the nanoporous structure is improved.

Fig. 15 is a graph showing the relationship between the gas detection layer according to Example 1, Example 2, Example 3, Example 4, Example 5 and Example 6 of the present invention before heat treatment And a specific surface area measured after heat treatment at 700 ° C for 1 hour.

As shown in FIG. 15, when the heat treatment is performed, the specific surface area decreases proportionally, while the specific surface area increases as the process pressure increases. That is, as the process pressure is increased, the increase of the specific surface area and the increase of the pore ratio are large, and it is confirmed that the ratio of the open pores that can easily penetrate into the gas detection layer 10 is increased. However, when the process pressure is increased to 2 Torr or more, the ratio of the open pores is almost constant, but the specific surface area is decreased.

It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

10: gas detection layer
20: substrate
30: Signal processing electrode
40: heater electrode
51: Baffle
52: deposition chamber
53: Evaporation source
54:
55: Exhaust

Claims (19)

In a gas sensor having a nanoporous structure,
Board;
A gas sensing layer formed in a nano-porous structure on one surface of the substrate through deposition of evaporated particles and having a density gradient formed by a relative density difference in one direction from one direction inside;
A signal processing electrode provided on the substrate and in contact with the gas detection layer; And
An insulating layer formed between the gas sensing layer and the substrate or between the signal processing electrode and the substrate to minimize heat emitted from the gas sensing layer and the signal processing electrode to the substrate;
/ RTI >
Wherein the insulating layer is formed of silicon oxide or silicon nitride and is located at a cutting position of the substrate formed by cutting a part of the substrate,
A density gradient is formed inside the gas sensing layer by changing the energy and size of the deposition particles by changing the process pressure in the deposition chamber with time,
The gas sensing layer is formed by gradually increasing or decreasing the process pressure in the density gradient inside the gas sensing layer so that the relative density is continuously increased or decreased in the outward direction of the thickness of the gas sensing layer and,
Wherein the adhesion between the substrate and the gas sensing layer is increased or decreased by a density gradient in the gas sensing layer.
The method according to claim 1,
Wherein the gas sensing layer has a specific surface area of 5 to 300 m < ² > / g.
The method according to claim 1,
Wherein the gas sensing layer has a density ratio (in terms of bulk) of 0.01 to 40%.
delete The method according to claim 1,
Wherein the gas sensing layer is formed by thermal evaporation using a baffle.
The method of claim 5,
Wherein the baffle has a function of suppressing radiation, convection and conduction of heat generated by the heat source of the thermal vapor deposition.
The method of claim 5,
Wherein the baffle is formed with a perforated hole for movement of the deposition particles.
The method of claim 5,
Wherein the baffle is formed of at least one material selected from the group consisting of a metal, an alloy, and a ceramic material.
The method according to claim 1,
Wherein the process pressure of the deposition is in the range of 0.01 to 10 Torr.
The method according to claim 1,
Wherein the gas sensing layer is formed of a metal or a metal oxide or is formed of a mixture of a metal and a metal oxide.
The method of claim 10,
The metal oxide may be at least one selected from the group consisting of Sn, Ni, Cu, Ti, V, Cr, Mn, Fe, (Ag), gold (Au), platinum (Pt), iridium (Ir), ruthenium (Ru), lithium (Li), aluminum (Al) And at least one material selected from the group consisting of oxides of antimony (Sb), bismuth (Bi), magnesium (Mg), silicon (Si), indium (In), lead (Pb) and palladium (Pd) A gas sensor comprising a nanoporous structure.
The method of claim 10,
The metal may be at least one selected from the group consisting of Au, Ag, Pd, Al, Cu, Cr, Fe, Mg, (Ni), Ti, Zn, Pb, V, Cb, Er, Ca, Hol, Wherein the at least one material is at least one material selected from the group consisting of Sc, Tb, Mo, and Pt.
The method according to claim 1,
Wherein the substrate is formed of a metal, ceramic, plastic, or paper.
The method according to claim 1,
Wherein a temperature of the substrate is increased when a current is applied to the heater electrode and the signal processing electrode provided on one surface of the substrate.
The method according to claim 1,
Characterized in that the gas sensing layer comprises a network which simultaneously comprises a mesopore with a diameter of 1.0 to 100 nanometers and a macropore with a diameter of 0.5 micrometers or more. A gas sensor comprising a porous structure.
A method of manufacturing a gas sensor having a nanoporous structure according to claim 1,
(I) providing the substrate provided with the signal processing electrode and the heater electrode;
(Ii) fixing the substrate to the deposition chamber and bringing the inside of the deposition chamber into a vacuum state;
(Iii) injecting a process gas into the deposition chamber in a vacuum state to form a process pressure;
(Iv) setting the temperature of the substrate to 50 DEG C or lower;
(V) in the deposition chamber, raising the temperature of the heat source containing the deposition material to form the vapor of the deposition material; And
(Vi) depositing the deposited particles generated in step (v) on the substrate to form the gas sensing layer;
The method of claim 1, wherein the nanoporous structure comprises a nanoporous structure.
18. The method of claim 16,
Wherein the step (ii) further comprises the step of providing a baffle at a predetermined position between the substrate and the evaporation source.
18. The method of claim 16,
Wherein the gas sensing layer is formed only on a part of the substrate according to the shape of the shape plate ridge in the step (v), wherein a shape plate is provided at a predetermined position between the substrate and the evaporation source, Wherein the gas sensor has a structure.
18. The method of claim 16,
Further comprising the step of heat-treating the gas sensing layer, the substrate or the signal processing electrode at a temperature of 200 to 1000 degrees Celsius after the step (vi) Gt;

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