WO2005078422A1

WO2005078422A1 - Method for manufacturing micro-structure catalytic combustion type gas sensor, and gas sensor using the micro-structure catalytic combustion gas sensor

Info

Publication number: WO2005078422A1
Application number: PCT/KR2005/000436
Authority: WO
Inventors: Won-Bae Lee
Original assignee: Seju Engineering Co., Ltd.
Priority date: 2004-02-16
Filing date: 2005-02-16
Publication date: 2005-08-25
Also published as: KR20050081691A

Abstract

Provided is a composite gas sensor provided with compensating device by miniaturizing a catalytic combustion sensor, and the object of the present invention is to provide a composite gas sensor to measure a gas reaction pattern more precisely than a semiconductor composite sensor. It is, therefore, an object of the present invention to provide a micro-structure catalytic combustion gas sensor, and sensing ability improved than using a single sensor by providing a composite gas sensor is integrated with the semiconductor in the catalytic combustion gas sensor, and the composite gas sensor which can sense a gas reaction pattern more precisely than semiconductor composite sensor. A gas sensor in accordance with another aspect of the present invention, includes: a substrate, two electrodes formed on the substrate; a heater electrically connected to two electrodes to supply a heat and the conducting line working as a gas sensing device; a catalytic combustible gas sensing material by coating an alumina carrier in the form of paste, wherein the alumina carrier is obtained by highly diffusing a catalyst on the conductive pattern; and at least one groove formed by etching portions of the substrate below the heaters to increase a thermal efficiency of the sensor. In accordance with present invention, there is provided a method for sensing a gas by using the composite gas sensor integrating the catalytic combustion gas sensor and the semiconductor gas sensor, including the steps of: operating semiconductor gas sensing unit at an initial operating environment if the sensor is turned on, and the operation of the sensor is started in order to sense a gas; identifying whether the gas is measured or not through the semiconductor gas sensing unit; operating the catalytic combustible gas sensing unit and the semiconductor gas sensing unit.

Description

METHOD FOR MANUFACTURING MICRO-STRUCTURE CATALYTIC COMBUSTION TYPE GAS SENSOR, AND GAS SENSOR USING THE MICRO- STRUCTURE CATALYTIC COMBUSTION GAS SENSOR Description Technical Field

The present invention relates to a method for manufacturing a micro-structure catalytic combustion type gas sensor and a composite sensor using the same; and, more particularly, to a method for manufacturing a micro- structure catalytic combustion type gas sensor by using a micro-electro mechanical system (MEMS) , a single and a composite gas sensors using the method and a method for sensing a gas by using the same.

Background Art

Generally, a catalytic combustion type gas sensor used for detecting the combustible gas is a sense device using the change of the heating line e.g., a platinum line, generated by raising the temperature of the device due to a combustion heat of sensing gas. A conventional catalytic combustion type gas sensor demands a lot of power for being heated since it has a large detecting surface in a shape of bead as well as it is manufactured in manual in producing structures and raising detectors. Generally, the types of gas sensor are classified into a semiconductor type, a catalytic combustion type, a Galvani type, a potentiostatic type and an optical fiber type. Each sensor is used differently according to the^' types and the concentration of gases. Therefore, using a single sensor for many hours causes the problems such as the signal change, the deterioration of the instrumentation device capability and the occurrence of the malfunction. Particularly, if only the catalytic combustion type gas sensor is used for many hours, the malfunction occurs and the life time is shortened. That is, since catalytic combustion type gas sensor is operated in a high temperature ranging from 700°C to 800°C, the miniaturization of the gas sensor by a conventional method damages the substrate due to the high temperature, and shortens the life time of the gas sensor, which will in turn become difficult in miniaturizing. In order to solve the problem, a composite sensor compositely using a semiconductor type sensor has been proposed. That is, the method is to increase the selectivity of the gas detection by using various catalysts. Referring to Fig. 1, the composite sensor in accordance with the conventional technology is described herein below. Fig. 1 is the perspective view of one embodiment for a composite sensor composing a conventional semiconductor type gas sensor in an array method. Fig. 1 is a sensing device of composite gas sensor employing a semiconductor gas sensor. As shown in Fig. 1, a composite sensor integrated with a semiconductor gas sensor by a conventional technology includes: an alumina substrate 10; sensing material 40 as a plurality of sensors catalyst positioned on the top of the alumina substrate 10; a plurality of electrodes to measure the resistance change of the sensing material 40; and a platinum heater providing the heat to the sensing material. That is, by compositely integrating a plurality of sensing materials sensing for a plurality of gases different from each other, the selectivity to the gas of semiconductor sensor can be increased. However, since the above method integrates different catalyst to the same kind sensing material, each unit material shows similar gas reaction pattern, thereby causing a problem is difficult to have the precise quantization and selectivity according to the gas concentration. In addition, in characteristics according to a gas sensor form, the semiconductor sensor has a merit to use semi-permanently,_, but also has a problem that the reliability is lower than that of the catalytic gas sensor, which lowers the reliability of the measured value than

^"that of the catalytic combustion gas sensor. It is also the problem that a difficult algorism such as a chaos, a pattern recognition or the like is used in order to implement the same sensor. And, the above composite sensor has another problem requiring needs a lot of power to implement the platinum heater of each sensor. And, since it is difficult to miniaturize catalytic combustion gas sensor, the manufacture of a composite sensor using catalytic combustion gas sensor becomes difficult.

Disclosure Technical Problem

It is, therefore, an object of the present invention to provide a micro-structure catalytic combustion gas sensor, and sensing ability improved than using a single sensor by providing a composite gas sensor integrated with the semiconductor in the catalytic combustion gas sensor, and the composite gas sensor which can sense a gas reaction pattern more precisely than semiconductor composite sensor. It is, therefore, another object of the present invention to provide the composite gas sensor that when integrating the semiconductor gas sensor in the catalytic combustion gas sensor, semiconductor sensor is used in a general state, but gas sensing method to measure a gas reaction pattern by the catalytic combustion gas sensor is used in a state that the gas is detected, which can extend the life time of the sensor and make the sense ability more precise. 5 Technical Solution

1. In accordance with one aspect of the present invention, there is provided a method for manufacturing a0 micro-structure catalytic combustion type gas sensor, comprising the steps of: forming a sensor substrate by forming a pair of thin insulation layers on both surfaces of a silicon substrate; forming at least one window by locally etching portions of one of the thin insulation5 layers of the sensor substrate to expose the silicon substrate; forming a conductive pattern provided with at least one heater and a plurality of electrodes, wherein the conductive pattern is extended to both ends of the insulation layer with crossing tops of the windows formed0 on the substrate; forming at least one groove by etching portions below the heaters which are exposed by the windows; and forming at least one catalytic combustible sensing material by coating an alumina carrier in a form of paste, wherein the alumina carrier is obtained by highly5 diffusing a catalyst such as platinum and palladium on the conductive pattern. In accordance with another aspect of the present invention, there is also provided a gas sensor, including: a substrate; a plurality of electrodes formed on the substrate; at least one heater electrically connected to two electrodes to supply a heat; at least one catalytic combustible gas sensing device formed by coating an alumina carrier obtained by highly diffusing a catalyst on tops of the heaters; and at least one groove formed by etching5 portions of the substrate below the heaters to increase a thermal efficiency of the sensor. In accordance with another aspect of the present invention, there is also provided gas sensor, further including: at least one heater including the same structure with the gas sensor; a plurality of electrodes connected to the heater; at least one compensating device formed on tops of the heaters; and at least one groove formed by etching portions of the substrate below the heaters. In accordance with another aspect of the present invention, there is also provided a gas sensor including: at least one heater including a material similar to that of the gas sensor; a plurality of electrode connected to the heaters; at least one semiconductor sensing device obtained by coating and sintering an oxide semiconductor doped with a platinum (Pt) on the heaters; a plurality of resistance sensing lines for measuring the resistance of the semiconductor sensing devices; and at least one groove formed by etching portions of the substrate below the heaters . In accordance with another aspect of the present invention, there is also provided a gas sensor, wherein the catalyst of the catalytic combustible sensing devices are a material selected from a group consisting of a platinum(Pt) , a palladium (Pd) or a combination thereof. In accordance with another aspect of the present invention, there is also provided a method for sensing a gas by using a sensor integrated with a catalytic combustible gas sensing unit provided with a catalytic combustible gas sensing device and a semiconductor gas sensing unit in a gas sensor separated with each other, including; operating the semiconductor gas sensing unit at an initial operating environment; identifying whether the gas is measured or not through the semiconductor gas sensing unit; and operating the catalytic combustible gas sensing unit and the semiconductor gas sensing unit, when the measuring gas is sensed at the step of identifying the gas . In accordance with still another aspect of the present invention, there is also provided a method, further comprising the steps of: quantizing a measured value such as a concentration of the measured gas through a microprocessor or the like; and displaying the quantized result so as to identify the result of the quantized result by the operator.

Advantageous Effects

As described in the above, the present invention can raise the selectivity of gas sensing by integrating a plurality of catalytic combustion gas sensing unit and improve the precision of the gas sensing by compensating the measured value. In addition, this invention can raise the selectivity of gas sensing by the sensing unit integration of heterogeneous method since integrating the semiconductor sensing unit with the catalytic combustion sensing unit. And, in case that gas is detected by the method of gas sensing according to the invention, and precise measuring is needed, that is, only in case that a gas is detected in the semiconductor gas sensing unit, the catalytic combustion sensing unit having a short life time than the semiconductor gas sensing unit is operated, which enables the life time of the catalytic combustion sensing unit to be expanded by reducing the unnecessary operation.

Description of Drawings

The above and other objects and features of the present invention will become apparent from the following description of the preferred embodiments given in conjunction with the accompanying drawings, in which: Fig. 1 is a perspective view illustrating an embodiment for a semiconductor composite sensor integrated with the semiconductor gas sensor in an array method according to a conventional art; Figs. 2 to 6 are cross-sectional diagrams showing a process for manufacturing a miniaturized catalytic combustion gas sensor in accordance with the present invention; Fig. 7 is a conceptual 'diagram showing a first embodiment of the catalytic combustion gas sensor provided with compensating devices in accordance with the present invention; Fig. 8 is a plan view showing a composite gas sensor integrated with a semiconductor gas sensor as a compensating device in the catalytic combustion gas sensor provided with a compensating device in accordance with a second embodiment of the present invention; Fig. 9 is a plan view showing a composite gas sensor integrated with the semiconductor gas sensor with the catalytic combustion gas sensor in accordance with a third embodiment of the present invention; and Fig. 10 is a flow chart showing a process for sensing a gas by using a composite gas sensor integrated with the semiconductor gas sensor and the catalytic combustion gas sensor in accordance with the second and third embodiments of the present invention.

Best Mode for the Invention

Other objects and aspects of the invention will become apparent from the following description of the embodiments with reference to the accompanying drawings, Figs. 2 to 10, which is set forth hereinafter. In accordance with a first embodiment of the present invention, as shown in Figs. 2 to 6, there is provided a method for manufacturing a micro-structure catalytic combustion type gas sensor using a Micro Electro Mechanical System(MEMS) technology. The method includes the steps of: forming a sensor substrate 100 by forming a pair of insulation layers 101 and 103, which is 0.1 to 10 microns, in particular, 2 microns, on both surfaces of a silicon substrate 100 (Fig. 2); forming at least one window 104 by locally etching central portions of one 101 of insulation layers of the sensor substrate 100 by a method such as a photolithography to expose the silicon substrate 102 (Fig. 3) ; forming a conductive pattern 130 functioning as a heater, a sensing unit and an electrode, wherein the conductive pattern is extended with crossing a top of the window 104 formed on the substrate 100 to both ends of the insulation layer(Fig. 4); forming at least one groove 110 below the conductive pattern by etching the part of the silicon substrate 102 exposed through the windows 104 with dipping the substrate 100 into an alkali solution, wherein the conductive pattern 130 is formed on the window 104 (Fig. 5) ; and forming a sensing material 106 by coating an alumina carrier in a form of paste, wherein the alumina carrier is obtained by highly diffusing a catalyst such as platinum and palladium on the conductive pattern 130. A gas sensor in accordance with another aspect of the present invention includes: a substrate 100; a first electrode 120 and a second electrode 121 formed on the substrate; a heater electrically connected to two electrodes to supply a heat and the first platinum conducting line 130 which is the conductive pattern working as a gas sensing device; a catalytic combustible gas sensing material 106 by coating an alumina carrier in the form of paste, wherein the alumina carrier is obtained by highly diffusing a catalyst on the conductive pattern 130; and at least one groove 110 formed by etching portions of the substrate below the heaters to increase a thermal efficiency of the sensor. That is, since the a thermal efficiency of the sensor is increased by the grooves 110, it is possible to carry out the catalytic combustion gas sensing with a low power, and prevent the life time of the substrate from being shortened by the high temperature, which also allows the catalytic combustion gas sensor to be manufactured with a small size. Fig. 7 is a conceptual diagram showing a second embodiment of catalytic combustion gas sensor provided with compensating devices in accordance with the present invention. A composite sensor in accordance with a second embodiment of the present invention, as shown in Fig. 7, further includes: a third electrode 122 on the substrate 100; a second platinum conducting line connecting the second electrode 121 and the third electrode 122 among the electrodes of the substrate 100; a catalytic combustion sensing material 107 by coating an alumina carrier in a form of paste, wherein the alumina carrier is obtained by highly diffusing a catalyst such as platinum and palladium on the second platinum conducting line 131; a groove 111 formed by etching a portion of a substrate below the second platinum conducting line 131 to increase a thermal efficiency of the sensor, into the gas sensor in accordance with the first embodiment. That is, if the regular temperature, preferably 200°C - 400°C is kept by providing an electric current, when a combustible gas is flowed into the composite gas sensor, the resistance within the conducting line is increased by the oxidization on the sensing device, i.e., the surfaces of the grooves 110 and 111, and the concentration of the detected gas can be detected since the change of the resistance is linearly proportion to the concentration of the gas. By constructing the composite sensor with a plurality of sensing devices, the composite sensor measures the gas more precisely by compensating the values measured at each sensing device. Although the composite sensor includes the two sensing materials 106 and 107 in accordance with the preferred embodiment of the present invention, but additional sensing materials can be added thereinto. Therefore, the present invention is capable of more precisely compensating by measurement value by the plurality of the sensing materials, an also detecting more kinds of gases by applying the variable catalysts to the variable sensing devices. Figs. 8 and 9 are plan views of the third and the fourth embodiments of the present invention integrated with the catalytic combustion sensor and the semiconductor gas sensor into one sensor. As shown in Fig. 8, in accordance with the third embodiment of the present invention, the composite sensor further includes the semiconductor sensing device into the first embodiment. The composite sensor comprises; a silicon substrate 200 provided with a first electrode 220, a second electrode 221, a third electrode 222 and a fourth electrode 223; a first platinum conducting line 230 connecting the second electrode 221 to the first electrode 220 of the substrate 220; a second platinum conducting line 231 connecting the second electrode 221 to the third electrode 222; a catalytic combustion sensing material 206 formed by coating an alumina carrier in a form of paste, wherein the alumina carrier is obtained by highly diffusing a catalyst such as platinum and palladium on the first platinum conducting line 230; a semiconductor sensing material 207 obtained by coating and sintering the oxide semiconductor doped with the platinum catalyst on the second platinum conducting line 231; a resistance sensing line 232 formed in such a way that it is contact to the semiconductor sensing material 207 with extending to the fourth electrode 223 to measure the resistance of the semiconductor sensing material; a first groove 210 and a second groove 211 formed by etching portions of the silicon substrate 200 below the first platinum conducting line 230 and the second conducting line 231. The fourth electrode 223 is not the electrode for providing the heat such as other electrodes, but is the resistance measuring electrode for measuring the resistance of the semiconductor sensing device 211 with connecting to the resistance sensing line. Such a structure can embody the merits of each sensor in one sensor by integrating the semiconductor gas sensor and the catalytic combustion gas sensor. That is, as described in the above, the merits of the semiconductor gas sensor are that the output change is large, that the time for the initial stabilization does not take long, that the life time is semi-permanent and that using by the low power is possible, and the merits of the catalytic combustion gas sensor are that sensing precision is high and that are not effected much by the temperature and humidity, and finally the gas sensor having both advantages of the durability of the semiconductor gas sensor and the precision of the catalytic combustion gas sensor is realized. The method to sense such a gas sensor is described as following with reference to Fig. 10. Fig. 9 is a fourth embodiment of the present invention further including the catalytic combustion sensing device as a compensating device for compensating the measured value of the catalytic combustion sensing device in accordance with the second embodiment. That is, Fig. 9 is the integration of the second embodiment and the third embodiment . In accordance with third embodiment of the present invention, as shown in Fig. 9, there is provided a composite gas sensor, inlcudes: a silicon substrate 300 provided with a first electrode 320, a second electrode 321, a third electrode 322, a fourth electrode 323 and a fifth electrode 324; a first platinum conducting line 330 connecting the first electrode 320 to the second electrode 321 of the silicon substrate 300; a second platinum conducting line 331 connecting the second electrode 321 to the third electrode 322 of the silicon substrate 300; the third platinum conducting line 332 connecting the third electrode 322 and the fourth electrode 323 of the silicon substrate 300; a first catalytic combustion sensing material 306 formed by coating an alumina carrier in a form of paste, wherein the alumina carrier is obtained by highly diffusing a catalyst such as platinum and palladium on the first platinum conducting line 330; a second catalytic combustion sensing material 307 formed by coating an alumina carrier in a form of paste, wherein the alumina carrier is obtained by highly diffusing a catalyst such as platinum and palladium on the second platinum conducting line 331; a semiconductor sensing material 308 obtained by coating and sintering the oxide semiconductor doped with a catalyst on the top of the third platinum conducting line 332; a resistance sensing line 333 formed in such a way that it is contact to the semiconductor sensing device 312 with extending to the fifth electrode 324 for measuring the resistance of the semiconductor sensing device; a first groove 310, a second groove 311 and a third groove 312 formed by etching portions of the silicon substrate below the first to third platinum conducting lines 330, 331 and 332. That is, only one catalytic combustion sensing material is equipped with in the second embodiment, on the other hand, since the second catalytic combustion sensing material 311 is added and functions as a compensating device in the third embodiment, it is possible to perform the more precise measurement. In the second or third embodiment, the number of the sensing device is not limited to the number related to the mentioned embodiment, but the selectivity and the precision of the gas sensing can be raised by integrating one or more semiconductor sensing device and one or more catalytic combustion sensing device. And, in the first to the third embodiments, each platinum conducting line functions as the heater providing heat and sensing the gas, and the material is not limited to the platinum, but the conducting lines are available. And, in the embodiments, as described in the "gas sensor and method for manufacturing thereof" which is filed with the Korean Patent Office by the applicant of the present invention and published in the Korean patent application No. 2002-0060694, the manufacturing method of each sensing unit wind the heater, the platinum conducting line below the sensing device, several times in zigzags, and as shown in Fig. 5, square symmetry, that is, by contriving the heat concentration by the form wound as the shape of "C", the gas sensor of the low power can be manufactured. In case that the catalytic combustion gas sensor and the semiconductor gas sensor are combined, that is, a new sensing method can be performed in order to implement the gas sensor satisfying the precision of the catalytic combustion gas sensor as well as the long life time of the semiconductor gas sensor as the gas sensor in accordance with the second embodiment or the third embodiment. Hereafter, the gas sensing method using composite gas sensor in accordance with the present invention will be described with reference to Fig. 10. Fig. 10 is a flow chart showing a process for sensing a gas by using a composite gas sensor integrated with the catalytic combustion gas sensor and the semiconductor gas sensor in accordance with the third and fourth embodiment of the present invention. In accordance with present embodiment of the present invention, as shown in Fig. 10, there is provided a method for sensing a gas, including the steps of: operating semiconductor gas sensing unit at an initial operating environment if the sensor is turned on, and the operation of the sensor is started in order to sense a gas at step 1002; identifying whether the gas is measured or not through the semiconductor gas sensing unit at step 1003; operating the catalytic combustible gas sensing unit and the semiconductor gas sensing unit at step 1005; quantizing the measured value such as a gas concentration of the measured gas through a micro processor or the like at step 1006; and displaying the quantized result so as to identify the quantized result by the operator at step 1007. That is, by controlling the operation of the composite gas sensor through the control unit such as a microprocessor having the program with the above-described algorism, if a gas is not detected in the semiconductor sensing material such as the semiconductor sensing material 207 in the second embodiment or the semiconductor sensing material 308 in the third embodiment, the procedure operating the semiconductor gas sensing device is continuously performed at step 1004, in case that the gas is detected, the procedure operating all sensing devices of the composite gas sensor are performed at step 1006, thereby more precisely quantizing the measurement value by ^■ compensating the measurement value. Therefore, in case that the gas does not exist, the catalytic combustion gas sensing device having a life time shorter than that of semiconductor gas sensing device is not operated and the semiconductor gas sensing device having a semi-permanent life time is operated. Therefore, the composite gas sensor of the present invention is capable of expending the life time of the ^' catalytic combustion gas sensing device incorporated thereinto. Hereafter, the composite gas sensor in accordance with the present invention and the operating effects of the sensing method will be described. The catalytic combustion gas sensor in accordance with the first embodiment has an advantage in operating at a low power by forming the groove 110 in the bottom and another advantage for preventing the life time from being shortened by the damage of the silicon substrate 100 due to the heat, since the substrate 100 are not in contact with the platinum conducting line 130. In the second embodiment, in case that a sensor is formed by being compositively combined with the catalytic combustion gas sensor like the composite gas sensor, the sensor can have more precise result than the semiconductor composite gas sensor, the superior selectivity to the single catalytic combustion gas sensor, and since the plurality of sensing devices can compensate the measured value and the sensor can have more precise result than the single catalytic combustion gas sensor. In the third and the fourth embodiments in accordance with the composite gas sensor, in case that the catalytic combustion gas sensor and the semiconductor gas sensor are formed compositely, the selectivity of the gas sensing can be increased since the each sensing device is operated by different method. And, the composite gas sensor can quantize with compensating the measured value precisely by measuring with use of several sensing devices. If the method operating the composite gas sensor is performed in accordance with the second and the third embodiments according to the order shown in Fig. 10, the semiconductor gas sensor having a long life time is mainly used, and the catalytic combustion gas sensor is operated in order to raise the precision only when the gas is detected, thereby allowing the catalytic combustion gas device to expand its life time. The present invention can provide a composite gas sensor having excellent characteristics in the life time of the whole gas sensors and in the precision or the like by the above-described operating effects. The present application contains subject matter related to Korean patent application No. 2004-10045, filed in the Korean Intellectual Property Office, the entire contents of which is incorporated herein by reference. While the present invention has been described with respect to certain preferred embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the scope and sprit of the invention as defined in the following claims.

Claims

What is claimed is:

1. A method for manufacturing a micro-structure catalytic combustion type gas sensor, comprising the steps of: 5 forming a sensor substrate by forming a pair of thin insulation layers on both surfaces of a silicon substrate; forming at least one window by locally etching portions of one of the thin insulation layers of the sensor substrate to expose the silicon substrate;0 forming a conductive pattern provided with at least one heater and a plurality of electrodes, wherein the conductive pattern is extended to both ends of the insulation layer with crossing tops of the windows formed on the substrate;5 forming at least one groove by etching portions below the heaters which are exposed by the windows; and forming at least one catalytic combustible sensing material by coating an alumina carrier in a form of paste, wherein the alumina carrier obtained by highly diffusing a0 catalyst such as platinum and palladium on the conductive pattern.

2. The method as recited in claim 1, wherein, in the step of forming the groove, the groove is obtained by5 etching the silicon substrate exposed through the windows with dipping the silicon substrate into an alkali solution.

3. A gas sensor, comprises: a substrate; a plurality of electrodes formed on the substrate; at least one heater electrically connected to two electrodes to supply a heat; at least one catalytic combustible gas sensing device formed by coating an alumina carrier obtained by highly5 diffusing a catalyst on tops of the heaters; and at least one groove formed by etching portions of the substrate below the heaters to increase a thermal efficiency of the sensor.

4. The gas sensor as recited in claim 3, wherein the alumina carrier is in a form y.

5. The gas sensor as recited in claim 3, further comprising: at least one heater including the same structure with the gas sensor; a plurality of electrodes connected to the heater; at least one compensating device formed on tops of the heaters; and at least one groove formed by etching portions of the substrate below the heaters.

6. The gas sensor as recited in anyone of claims 3 to 5, wherein the compensating devices are not reacting with a gas.

7. The gas sensor as recited in anyone of claims 3 to 5, wherein the compensating devices are made, by coating the alumina carrier.

8. The gas sensor as recited in anyone of claim 3 to 5, wherein the compensating devices are formed in such a way that the compensating devices form a Whiston Bridge shape with the catalytic combustible gas sensing devices.

9. The gas sensor as recited in anyone of claims 3 to 5, further comprising: at least one heater including a material similar to that of the gas sensor; a plurality of electrodes connected to the heaters; at least one semiconductor sensing device obtained by coating and sintering an oxide semiconductor doped with a platinum (Pt) on the heaters; a plurality of resistance sensing lines for measuring the resistance of the semiconductor sensing devices; and at least one groove formed by etching portions of the substrate below the heaters .

10. The gas sensor as recited in anyone of claims 3 to 5, wherein the catalyst of the catalytic combustible sensing devices are a material selected from a group consisting of a platinum(Pt) , a palladium(Pd) or a combination thereof.

11. The gas sensor as recited in claim 9, wherein the catalyst doped into the semiconductor sensing device includes a platinum (Pt) or palladium (Pd) .

12. The gas sensor as recited in anyone of claims 3 to 5, wherein the conductive pattern includes a platinum (Pt) .

13. The gas sensor as recited in anyone of clams 3 to 5, wherein the substrate includes a silicon.

14. A method for sensing a gas by using a sensor integrated with a catalytic combustible gas sensing unit provided with a catalytic combustible gas sensing device and a semiconductor gas sensing unit in a gas sensor in accordance with claim 9 or separated with each other, comprising the steps of; operating the semiconductor gas sensing unit at an initial operating environment; identifying whether the gas is measured or not through the semiconductor gas sensing unit; and operating the catalytic combustible gas sensing unit and the semiconductor gas sensing unit, when the measuring gas is sensed at the step of identifying the gas.

15. The method as recited in claim 14, further comprising the steps of: quantizing a measured value such as a concentration of the measured gas through a micro-processor or the like; and displaying the quantized result so as to identify the quantized result by the operator.