KR100316389B1 - A NOx Sensor And A Producting Methode of NOx Sensor - Google Patents
A NOx Sensor And A Producting Methode of NOx Sensor Download PDFInfo
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- KR100316389B1 KR100316389B1 KR1019990001567A KR19990001567A KR100316389B1 KR 100316389 B1 KR100316389 B1 KR 100316389B1 KR 1019990001567 A KR1019990001567 A KR 1019990001567A KR 19990001567 A KR19990001567 A KR 19990001567A KR 100316389 B1 KR100316389 B1 KR 100316389B1
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- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 claims abstract description 134
- 239000007789 gas Substances 0.000 claims abstract description 67
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 17
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 17
- 239000010703 silicon Substances 0.000 claims abstract description 17
- 238000004519 manufacturing process Methods 0.000 claims abstract description 16
- 238000004544 sputter deposition Methods 0.000 claims abstract description 11
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 9
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims abstract description 9
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 claims abstract description 6
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims abstract description 6
- 229910001873 dinitrogen Inorganic materials 0.000 claims abstract description 5
- 239000011810 insulating material Substances 0.000 claims abstract description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 3
- 239000012153 distilled water Substances 0.000 claims abstract description 3
- 229910052814 silicon oxide Inorganic materials 0.000 claims abstract description 3
- 238000005406 washing Methods 0.000 claims abstract 5
- 239000010409 thin film Substances 0.000 claims description 28
- 239000000758 substrate Substances 0.000 claims description 24
- 238000001514 detection method Methods 0.000 claims description 15
- 238000000151 deposition Methods 0.000 claims description 13
- 229910052782 aluminium Inorganic materials 0.000 claims description 12
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 12
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 8
- 230000008021 deposition Effects 0.000 claims description 7
- ZNOKGRXACCSDPY-UHFFFAOYSA-N tungsten trioxide Chemical compound O=[W](=O)=O ZNOKGRXACCSDPY-UHFFFAOYSA-N 0.000 claims description 6
- 229910052786 argon Inorganic materials 0.000 claims description 4
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical group Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 claims description 4
- 239000010408 film Substances 0.000 claims description 4
- 238000010438 heat treatment Methods 0.000 claims description 3
- 238000004506 ultrasonic cleaning Methods 0.000 claims description 3
- 229910052581 Si3N4 Inorganic materials 0.000 claims description 2
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 2
- 229910052757 nitrogen Inorganic materials 0.000 claims description 2
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims description 2
- 238000000034 method Methods 0.000 abstract description 15
- QGLKJKCYBOYXKC-UHFFFAOYSA-N nonaoxidotritungsten Chemical compound O=[W]1(=O)O[W](=O)(=O)O[W](=O)(=O)O1 QGLKJKCYBOYXKC-UHFFFAOYSA-N 0.000 abstract description 10
- 229910001930 tungsten oxide Inorganic materials 0.000 abstract description 10
- 230000035945 sensitivity Effects 0.000 abstract description 4
- -1 silicon nitroxide Chemical class 0.000 abstract description 3
- XSTXAVWGXDQKEL-UHFFFAOYSA-N Trichloroethylene Chemical compound ClC=C(Cl)Cl XSTXAVWGXDQKEL-UHFFFAOYSA-N 0.000 abstract 2
- 238000007747 plating Methods 0.000 abstract 2
- 238000001035 drying Methods 0.000 abstract 1
- UBOXGVDOUJQMTN-UHFFFAOYSA-N trichloroethylene Natural products ClCC(Cl)Cl UBOXGVDOUJQMTN-UHFFFAOYSA-N 0.000 abstract 1
- PIGFYZPCRLYGLF-UHFFFAOYSA-N Aluminum nitride Chemical compound [Al]#N PIGFYZPCRLYGLF-UHFFFAOYSA-N 0.000 description 26
- 238000010897 surface acoustic wave method Methods 0.000 description 22
- 239000004065 semiconductor Substances 0.000 description 10
- 239000013078 crystal Substances 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 4
- 238000001755 magnetron sputter deposition Methods 0.000 description 4
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 229910002091 carbon monoxide Inorganic materials 0.000 description 3
- 238000005229 chemical vapour deposition Methods 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 229920002120 photoresistant polymer Polymers 0.000 description 3
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 238000005530 etching Methods 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 238000010295 mobile communication Methods 0.000 description 2
- 238000001451 molecular beam epitaxy Methods 0.000 description 2
- 125000004433 nitrogen atom Chemical group N* 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- 229910018509 Al—N Inorganic materials 0.000 description 1
- 229910000640 Fe alloy Inorganic materials 0.000 description 1
- JMASRVWKEDWRBT-UHFFFAOYSA-N Gallium nitride Chemical compound [Ga]#N JMASRVWKEDWRBT-UHFFFAOYSA-N 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 1
- 229910006404 SnO 2 Inorganic materials 0.000 description 1
- 229910010413 TiO 2 Inorganic materials 0.000 description 1
- 229910052770 Uranium Inorganic materials 0.000 description 1
- 238000003916 acid precipitation Methods 0.000 description 1
- 238000003915 air pollution Methods 0.000 description 1
- 125000004429 atom Chemical group 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 238000003486 chemical etching Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000007772 electrode material Substances 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 239000003517 fume Substances 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 231100000252 nontoxic Toxicity 0.000 description 1
- 230000003000 nontoxic effect Effects 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 239000005416 organic matter Substances 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- 238000006552 photochemical reaction Methods 0.000 description 1
- IEQIEDJGQAUEQZ-UHFFFAOYSA-N phthalocyanine Chemical compound N1C(N=C2C3=CC=CC=C3C(N=C3C4=CC=CC=C4C(=N4)N3)=N2)=C(C=CC=C2)C2=C1N=C1C2=CC=CC=C2C4=N1 IEQIEDJGQAUEQZ-UHFFFAOYSA-N 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000012495 reaction gas Substances 0.000 description 1
- 229910052594 sapphire Inorganic materials 0.000 description 1
- 239000010980 sapphire Substances 0.000 description 1
- 239000007784 solid electrolyte Substances 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 239000002887 superconductor Substances 0.000 description 1
- 238000000427 thin-film deposition Methods 0.000 description 1
- DZKDPOPGYFUOGI-UHFFFAOYSA-N tungsten(iv) oxide Chemical compound O=[W]=O DZKDPOPGYFUOGI-UHFFFAOYSA-N 0.000 description 1
- DNYWZCXLKNTFFI-UHFFFAOYSA-N uranium Chemical compound [U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U][U] DNYWZCXLKNTFFI-UHFFFAOYSA-N 0.000 description 1
- 231100000925 very toxic Toxicity 0.000 description 1
- 238000010792 warming Methods 0.000 description 1
- 239000011787 zinc oxide Substances 0.000 description 1
- 229910052984 zinc sulfide Inorganic materials 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/0004—Gaseous mixtures, e.g. polluted air
- G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
- G01N33/0027—General constructional details of gas analysers, e.g. portable test equipment concerning the detector
- G01N33/0036—General constructional details of gas analysers, e.g. portable test equipment concerning the detector specially adapted to detect a particular component
- G01N33/0037—NOx
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- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Health & Medical Sciences (AREA)
- Medicinal Chemistry (AREA)
- Food Science & Technology (AREA)
- Combustion & Propulsion (AREA)
- Physics & Mathematics (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analyzing Materials By The Use Of Fluid Adsorption Or Reactions (AREA)
Abstract
Description
본 발명은 질소산화물 가스 센서 및 그 제조 방법에 관한 것으로, 오염 물질인 산화질소 가스를 주변 환경 조건과 관계없이 정밀하면서 빠르게 감지해 내는 가스 센서에 관한 것이다.BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nitrogen oxide gas sensor and a method of manufacturing the same, and more particularly to a gas sensor that detects nitric oxide gas, which is a pollutant, precisely and quickly regardless of surrounding environmental conditions.
최근 대도시 대기 오염의 주원인은 과거의 공장 매연과 난방 연료에서 자동차 배기 가스로 바뀌고 있다.In recent years, the major cause of air pollution in large cities is changing from past factory fumes and heating fuel to automobile exhaust.
자동차 배기 가스의 성분은 주로 미연소된 탄화수소(CHx), 질소산화물(NOx),일산화탄소(CO), 이산화탄소(CO2) 및 수증기로 되어 있으며, 그 중에서도 질소 산화물(NOx)은 인체에 매우 유독하며, 광화학 반응으로 오존을 생성시켜 여름철 스모그 현상, 지구의 온난화 및 산성비의 원인이 되었다.Car exhaust consists mainly of unburned hydrocarbons (CHx), nitrogen oxides (NOx), carbon monoxide (CO), carbon dioxide (CO 2 ) and water vapor. Among them, nitrogen oxides (NOx) are very toxic to human body. In addition, photochemical reactions generate ozone, causing summer smog, global warming and acid rain.
따라서, 이러한 질소산화물의 감지 및 제거에 관한 관심 증가와 새로운 센서에 대한 개발이 요구되고 있으며, 이러한 환경 센서의 개발은 자동차나 산업체에서 배출되는 가스는 물론, 대기 중의 환경을 감시함으로써 주거 환경을 개선하고 자연환경을 보호하는데 기여할 것이다.Therefore, increasing interest in the detection and removal of nitrogen oxides and the development of new sensors are required, and the development of such environmental sensors improves the residential environment by monitoring the atmosphere in the atmosphere as well as the gases emitted from automobiles and industries. And contribute to protecting the natural environment.
지금까지 질소 산화물(NOx) 센서는 고체 전해질을 이용한 전기 화학 센서, YBa2Cu3O7-8박막을 이용한 초전도체 센서, 산화물 반도체 박막이나 프타로시아닌(phthalocyanine)과 같은 유기물 반도체를 사용하여 표면 탄성파(SAW) 특성을 이용한 센서, SnO2, WO3, ZnO, TiO2등 반도체 산화물을 이용한 반도체식 센서 등이 발표된 바 있다.To date, NOx sensors have been characterized by electrochemical sensors using solid electrolytes, superconductor sensors using YBa 2 Cu 3 O 7-8 thin films, oxide semiconductor thin films or organic semiconductors such as phthalocyanine. Sensors using SAW characteristics, semiconductor sensors using semiconductor oxides such as SnO 2 , WO 3 , ZnO, and TiO 2 have been published.
기존에 주로 이용되어 왔던 가스 센서의 경우 과거의 반도체형, 벌크형(bulk type)이 주로 많이 이용되고 있으나, 이러한 기존의 가스 센서들은 주위의 습도에 매우 민감하게 반응함으로써 센서의 신뢰도가 저하되며, 특히, 반도체식 가스 센서의 경우에 80∼90습도 환경에서는 센서의 민감도가 감소하여 센서로의 이용이 불가능해진다.In the case of gas sensors that have been mainly used in the past, semiconductor type and bulk type of the past are mainly used, but these conventional gas sensors are very sensitive to ambient humidity, and thus the reliability of the sensor is deteriorated. In the case of the semiconductor gas sensor, the sensitivity of the sensor is reduced in the 80 to 90 humidity environment, making it impossible to use as a sensor.
뿐만 아니라, 센서가 위치한 주위 환경의 온도 변화에 따라서도 민감도 특성이 변화하여 신뢰도가 저하되는 문제점이 있었다.In addition, there is a problem in that the sensitivity characteristic is also changed in accordance with the temperature change of the surrounding environment where the sensor is located, the reliability is lowered.
최근 이러한 습도의 영향을 받지 않는 센서로써 표면 탄성파(SAW, Surface Acoustic Wave)의 주파수 변화를 이용하는 벌크형 가스 센서들이 국내외에서 연구되고 있다.Recently, bulk gas sensors using frequency variation of surface acoustic wave (SAW) as a sensor not affected by humidity have been studied at home and abroad.
SAW 가스 센서는 주파수 형태의 출력 신호를 사용하므로 반도체식 가스 센서보다 더욱 정밀한 양까지 측정이 가능하나 지금까지 국내외에서 연구된 벌크형 SAW 가스 센서에는 압전 단결정을 기판으로 사용하였기 때문에 상기의 장점에도 불구하고 소형화, 대량 생산, 가격 경쟁력이 문제가 되었다.SAW gas sensor uses frequency type output signal, so it can measure more precise quantity than semiconductor gas sensor.Because of the SAW gas sensor studied so far, piezoelectric single crystal is used as a substrate, despite the above advantages Miniaturization, mass production, and price competitiveness became a problem.
특히, 압전 특성이 우수하며, 타 압전 물질에 비하여 가격이 저렴할 뿐 아니라 c축 성장이 용이한 산화아연(ZnO)을 많이 이용했는데, 이 산화아연(ZnO)은 질소산화물(NOx) 가스에 민감하고, 주위의 수분 함량에 대한 안정성이 저하되는 문제점이 있었기 때문에 가스 센서로써 신뢰도가 저하되는 문제점이 있었다.Particularly, zinc oxide (ZnO), which has excellent piezoelectric properties, is cheaper than other piezoelectric materials, and has easy c-axis growth, is used. The zinc oxide (ZnO) is sensitive to nitrogen oxide (NOx) gas. Because of this, there was a problem that the stability of the ambient moisture content is lowered, so there was a problem that the reliability was lowered as a gas sensor.
본 발명은 상기한 바와 같은 종래의 반도체식 가스 센서가 안고 있는 문제점을 해결하기 위한 것으로, 압전 단결정 대신 질화알루미늄(AlN)의 압전 박막을 사용하여 질소 산화물(NOx) 가스 센서를 제작하여 소형, 경량, 저 가격, 고감도의 특성을 갖는 질소산화물 가스 센서 및 그 제조 방법을 제공하는데 그 목적이 있다.The present invention is to solve the problems of the conventional semiconductor gas sensor as described above, by using a piezoelectric thin film of aluminum nitride (AlN) instead of a piezoelectric single crystal to produce a nitrogen oxide (NOx) gas sensor, small, lightweight It is an object of the present invention to provide a nitrogen oxide gas sensor having a low cost, high sensitivity, and a manufacturing method thereof.
본 발명은 상기한 목적을 달성하기 위하여, 실리콘 기판 위에 압전성을 갖는 질화알루미늄(AlN)을 증착하고, 그 위에 기준 신호용 IDT 한 쌍 및 감지 신호용 IDT 한 쌍과, 한 쌍의 감지 신호용 IDT 사이에 질소 산화물(NOx)과 반응하여 감지하는 산화텅스텐(WO3) 감지막을 증착하여 이루어지는 것을 특징을 하는 질소산화물 가스 센서 및 그 제조 방법을 제공한다.In order to achieve the above object, the present invention is to deposit a piezoelectric aluminum nitride (AlN) on a silicon substrate, and thereon nitrogen between a pair of reference signal IDT and a pair of detection signal IDT and a pair of detection signal IDT A nitrogen oxide gas sensor and a method of manufacturing the same are provided by depositing a tungsten oxide (WO 3 ) sensing film that reacts with an oxide (NOx).
도 1은 본 발명에 따른 질소산화물 가스 센서의 제 1실시예를 나타낸 사시도.1 is a perspective view showing a first embodiment of a nitrogen oxide gas sensor according to the present invention.
도 2는 본 발명에 따른 질소산화물 가스 센서의 제 2실시예를 나타낸 사시도.Figure 2 is a perspective view showing a second embodiment of a nitrogen oxide gas sensor according to the present invention.
도 3은 본 발명에 따른 질소산화물 가스 센서를 이용한 실제 회로 구성을 나타낸 회로도.3 is a circuit diagram showing an actual circuit configuration using a nitrogen oxide gas sensor according to the present invention.
본 발명에 따른 질소산화물 가스 센서 및 그 제조 방법의 구성 및 작용에 대하여 본 발명의 일 실시예를 통하여 상세하게 설명한다.The structure and operation of the nitrogen oxide gas sensor and the method of manufacturing the same according to the present invention will be described in detail through an embodiment of the present invention.
첨부한 도면, 도 1은 본 발명에 따른 질소산화물 가스 센서의 제 1실시예를 나타낸 사시도이고, 도 2는 본 발명에 따른 질소산화물 가스 센서의 제 2실시예를 나타낸 사시도이며, 도 3은 본 발명에 따른 질소산화물 가스 센서를 이용한 실제 회로 구성을 나타낸 회로도이다.1 is a perspective view showing a first embodiment of the nitrogen oxide gas sensor according to the present invention, Figure 2 is a perspective view showing a second embodiment of the nitrogen oxide gas sensor according to the present invention, Figure 3 A circuit diagram showing an actual circuit configuration using a nitrogen oxide gas sensor according to the invention.
일반적으로, 탄성표면파(SAW)는 1885년 로드 레이라이(Lord Rayleigh)에 의해 지구 표면을 전파하는 지진파로 발견된 이래 여러 연구자들이 그 응용 범위를 찾아오다 1969년에 미국 스탠포드(Stanford)대학 연구팀이 새로운 형태의 IDT(interdigital transducer)를 채용하여 전기 신호를 음향 탄성파로 변환하는 방법을 발표하였고, 1970년대에는 SAW소자가 처음으로 군용 레이더 장비의 광역 스펙트럼용으로 개발된 후로 민수용으로 응용이 시작되었다.In general, surface acoustic wave (SAW) has been discovered by Rod Rayleigh in 1885 as a seismic wave that propagates the Earth's surface. Several researchers have found its application. In 1969, a team of researchers from Stanford University A method of converting electrical signals to acoustic acoustic waves by adopting a form of interdigital transducer (IDT) was introduced. In the 1970s, SAW devices were first developed for the broad spectrum of military radar equipment.
이렇게 발전된 SAW는 두 매질의 경계면을 따라 전파하는 종파로서, 탄성파에 의해 전달된 기계적 에너지가 표면에서 수직으로 한파장 내에 집중한 것을 말한다. 고체에서 전달되는 파의 속도는 약 103∼104m/sec 이므로 매우 높은 주파수를 갖는 신호를 전송할 수 있다. 따라서 표면 상태를 변화시키면 쉽게 SAW의 전달 특성을조절할 수 있으며 파의 속도가 고체에서 약 103∼104m/sec 정도이므로 VHF 및 UHF 대역에서 작동하는 소자에 응용할 수 있어서, 현재까지 TV나 VCR등 A/V기기의 중간 주파수 필터로 많이 사용되고 있으며, 이동 통신 기기에서는 삽입 손실이 크고, 고주파 대역에서의 특성이 불안정한 점 때문에 제한적으로 사용되어 왔다.This advanced SAW is a longitudinal wave that propagates along the interface of two media, in which the mechanical energy delivered by the acoustic wave is concentrated in one wavelength perpendicular to the surface. Speed of the wave transmitted from the solids is about 10 3 ~10 4 m / sec can transmit a signal having a still higher frequency. Therefore, by changing the surface state, it is possible to easily control the propagation characteristics of the SAW. Since the wave speed is about 10 3 to 10 4 m / sec in solid, it can be applied to devices operating in the VHF and UHF bands. It is widely used as an intermediate frequency filter for A / V equipment, and has been used in mobile communication equipment because of its large insertion loss and unstable characteristics in the high frequency band.
그러나, 최근 새로운 IDT(Interdigital transducer) 전극 구조와 압전 박막물질의 도입으로 저손실화 및 고주파 영역에서의 특성 안정화 등을 실현하여 현재는 휴대 전화기의 중간주파수단 및 페이저(pager)의 수신 필터 등 거의 모든 이동 통신 기기에 사용되고 있다.However, with the introduction of a new IDT (Interdigital transducer) electrode structure and piezoelectric thin film material, low loss and stabilization of characteristics in the high frequency range have been realized. It is used in mobile communication devices.
SAW를 이용하는 소자에는 대역 통과 필터뿐만 아니라 공진기, 발진기, 펄스압축기 및 가스 센서 등이 있다.Devices using SAW include resonators, oscillators, pulse compressors and gas sensors as well as band pass filters.
SAW 가스 센서는 압전체 표면에 존재하는 빗살무늬 모양의 전극인 IDT에 전압을 가함으로써 SAW를 여기시키고 검출하므로, 기준 신호를 의한 IDT와 검출 신호를 위한 IDT 등 2쌍의 IDT 전극이 필요하다.The SAW gas sensor excites and detects the SAW by applying a voltage to the IDT, which is a comb-shaped electrode, present on the surface of the piezoelectric body. Therefore, two pairs of IDT electrodes, such as an IDT based on a reference signal and an IDT for a detection signal, are required.
본 발명에 따른 산화질소 가스 센서의 제 1실시예는 도 1에 나타낸 바와 같이, 실리콘 기판 위에, 질화알루미늄(AlN) 박막을 증착한 후에, 다시 기준 신호 검출용 IDT 한 쌍과, 가스 감지 신호 검출용 IDT 한 쌍과, 산화질소 가스를 감지하는 산화텅스텐(WO3) 소자를 형성하였다.According to the first embodiment of the nitrogen oxide gas sensor according to the present invention, after depositing an aluminum nitride (AlN) thin film on a silicon substrate, a pair of IDTs for detecting a reference signal and a gas sensing signal are detected. A pair of IDTs and a tungsten oxide (WO 3 ) element for sensing nitrogen oxide gas were formed.
여기서, 실리콘 기판 위에 질화알루미늄(AlN) 박막을 증착하는 과정은 다음과 같다.Here, the process of depositing an aluminum nitride (AlN) thin film on a silicon substrate is as follows.
여기서, 질화알루미늄은 알루미늄과 질소 원자가 육방 정계 구조를 가지는 Ⅲ-Ⅴ족 화합물 반도체로서 매우 높은 열전도도, 낮은 열팽창계수, 매우 큰 전기저항, 적당한 유전 특성과 기계적 강도, 강한 압전 특성, 수분에 대하여 안정한 특성뿐만 아니라, 기존의 압전 재료에 비해 2배 이상의 SAW 전파속도를 보이기 때문에 본 발명과 같은 NOx 가스 센서와 고주파 SAW 필터의 제조에 가장 적합한 압전 재료이다.Here, aluminum nitride is a group III-V compound semiconductor having a hexagonal structure of aluminum and nitrogen atoms, and has very high thermal conductivity, low thermal expansion coefficient, very large electrical resistance, moderate dielectric and mechanical strength, strong piezoelectric properties, and stable to moisture. In addition to the characteristics, since the SAW propagation speed is more than twice that of the conventional piezoelectric material, it is the most suitable piezoelectric material for the production of the NOx gas sensor and the high frequency SAW filter as the present invention.
이러한 특성을 갖고 있는 질화알루미늄(AlN) 박막을 제조하는 방법에는 스퍼터링(Sputter)법, CVD(Chemical Vapor Deposition)법 및 MBE(Molecular Beam Epitaxy)법 등이 있으며, 일반적인 CVD법이나 MBE방법으로는 900℃이상의 온도에서 에피택셜하게 성장한 질화알루미늄(AlN) 박막을 얻을 수 있으나, 높은 증착 온도 때문에 실제의 소자 제조 공정에는 적용시키기 어려우며, 반면에 스퍼터링 법은 300℃이하에서 질화알루미늄(AlN) 박막의 제조가 가능하고 두께 균일성이나 결정의 c축 배향성이 우수하여 가장 널리 사용되고 있다.A method of manufacturing an aluminum nitride (AlN) thin film having such characteristics includes sputtering, chemical vapor deposition (CVD), and molecular beam epitaxy (MBE), and as a general CVD or MBE method, 900 Although aluminum nitride (AlN) thin films epitaxially grown at temperatures above C can be obtained, it is difficult to apply them to the actual device fabrication process due to the high deposition temperature, whereas sputtering method produces aluminum nitride (AlN) thin films under 300C. It is most widely used because of excellent thickness uniformity and crystallographic c-axis orientation.
본 발명에서는 SAW를 이용한 질소산화물(NOx) 가스 센서를 개발하기 위하여 실리콘웨이퍼 기판 위에 고주파 마그네트론 스퍼터링 법으로 c 축 배향성이 우수한 질화알루미늄(AlN) 박막을 증착하였다.In the present invention, in order to develop a nitrogen oxide (NOx) gas sensor using SAW, an aluminum nitride (AlN) thin film having excellent c-axis orientation was deposited on a silicon wafer substrate by a high frequency magnetron sputtering method.
여기서, 질화알루미늄(AlN)은 질소 원자가 육방 조밀 충진(HCP)한 격자 구조의 4배위 위치에 알루미늄(Al) 원자가 자리하는 전형적인 wurtzite구조를 가지고 있으며 공유결합과 이온결합의 중간 물성을 가지고 있으며, 이러한 질화알루미늄(AlN)의 격자상수는 a=3.211Å, c=4.982Å이며, N-Al-N의 결합각은107.9°이다.Here, aluminum nitride (AlN) has a typical wurtzite structure in which aluminum (Al) atoms are located at the fourth coordination position of the hexagonal densely packed (HCP) lattice structure with nitrogen atoms, and has intermediate properties of covalent and ionic bonds. The lattice constant of aluminum nitride (AlN) is a = 3.211 kPa, c = 4.982 kPa, and the bonding angle of N-Al-N is 107.9 °.
이러한 결정 구조를 갖는 질화알루미늄(AlN)은 2400℃ 이상의 높은 녹는점을 가지며, 열적·화학적으로 대단히 안정하며, 열전도도는 2000W/mK로 대단히 크며, 2.56×10-6/K의 매우 작은 열팽창 계수를 갖고 있다.Aluminum nitride (AlN) having such a crystal structure has a high melting point of 2400 ° C. or higher, is very stable thermally and chemically, and has a very high thermal conductivity of 2000 W / mK and a very small coefficient of thermal expansion of 2.56 × 10 −6 / K. Have
또한 5000∼6000m/s의 아주 빠른 탄성 표면파 전파 속도를 가질 뿐만 아니라 넓은 에너지 밴드갭(6.2eV)의 반도체 특성을 갖고 있다.In addition, it has a very fast surface acoustic wave propagation speed of 5000 to 6000 m / s, as well as semiconductor characteristics with a wide energy bandgap (6.2 eV).
반면에 질화알루미늄(AlN)이 산소 등의 불순물을 함유하고 있으면 열전도도, 전기저항, 광학적 투명도 등이 낮아지는 단점을 가지고 있다.On the other hand, when aluminum nitride (AlN) contains impurities such as oxygen, thermal conductivity, electrical resistance, optical transparency, and the like have a disadvantage.
질화알루미늄(AlN)은 질화갈륨(GaN)과 비슷한 화학적 식각(chemical etching)에 대한 저항성을 보이며, 77K에서 1269K 까지의 넓은 온도 구간에서 열팽창 계수의 변화는 매우 작을 뿐만 아니라, 독성이 전혀 없으며 다양한 물질에 대하여 부식성이 매우 낮으며, 용융된 알루미늄과 반응하지 않고 우라늄, 리튬 등의 여러 종류의 철합금에 대하여 비활성을 나타낸다.Aluminum nitride (AlN) exhibits resistance to chemical etching similar to gallium nitride (GaN), and its thermal expansion coefficient is not only very small, but also non-toxic and varied in a wide temperature range from 77K to 1269K. Corrosiveness is very low, and it does not react with molten aluminum and exhibits inertness against various kinds of iron alloys such as uranium and lithium.
그러나, 질화알루미늄(AlN)은 알루미늄과 산소 등에 대한 반응성이 크기 때문에 자연 상태에서 존재하지 않고 높은 온도에서 반응시켜 얻으며, 양질의 질화알루미늄(AlN)을 제조하기 위해서는 고순도 원료 물질과 산소를 배제한 환경이 필요하다.However, since aluminum nitride (AlN) is highly reactive to aluminum and oxygen, it does not exist in a natural state and is reacted at a high temperature.In order to manufacture high quality aluminum nitride (AlN), an environment in which high purity raw material and oxygen are excluded is required. need.
본 발명에서 실리콘 기판 위에 형성한 질화알루미늄(AlN) 박막은 Si(100 또는 111) 구조 위에 고주파 마그네트론 스퍼터링 법을 이용하여 제조하였다.In the present invention, an aluminum nitride (AlN) thin film formed on a silicon substrate was fabricated by using a high frequency magnetron sputtering method on a Si (100 or 111) structure.
질화알루미늄(AlN) 박막 증착시 기판의 청결 상태는 박막의 성장과 부착력 등의 물성에 영향을 주기 때문에 깨끗한 기판을 얻기 위해 유기물을 효과적으로 제거하는 TCE 80℃ 용액에서 30분간 초음파를 이용하여 초기 세척한 후 아세톤 및 메탄올에서 각각 30분씩 초음파 세척을 하였다. 그 후, 마지막으로 에탄올과 증류수에서 30분간 초음파 세척을 하였으며 질소 가스로 건조시켰다.During the deposition of aluminum nitride (AlN) thin film, the cleanliness of the substrate affects the properties of the thin film, such as growth and adhesion, so that it is initially cleaned using ultrasonic waves in a TCE 80 ℃ solution for 30 minutes in order to effectively remove organic matter. After ultrasonic cleaning for 30 minutes each in acetone and methanol. After that, the ultrasonic cleaning was finally performed in ethanol and distilled water for 30 minutes and dried with nitrogen gas.
질화알루미늄(AlN) 박막을 SAW 가스 센서 소자로 이용하기 위해서는 우수한 c축 배향성뿐만 아니라 높은 저항값이 요구되는데, 이에 영향을 미치는 요소로는 고주파 전력, 가스의 조성비, 박막 증착시 압력, 기판의 온도 등의 여러 가지 변수가 존재한다.In order to use the aluminum nitride (AlN) thin film as a SAW gas sensor element, not only excellent c-axis orientation but also high resistance value are required. The factors affecting this are high frequency power, composition ratio of gas, pressure during thin film deposition, and substrate temperature. There are a number of variables.
이를 위하여 본 발명에서 이용한 고주파 마그네트론 스퍼터링 장치는 직경이 3∼5인치 타겟(99.999, 고순도화학)을 사용하였으며, 타겟은 상하로 이동되도록 설계하였다. 고진공도를 갖기 위해서 650ℓ/min인 로터리펌프와 1500ℓ/sec의 배기 능력을 갖는 터보펌프로 구성하였다.To this end, the high frequency magnetron sputtering apparatus used in the present invention used a 3 to 5 inch diameter target (99.999, high purity chemistry), and the target was designed to move up and down. In order to have a high vacuum, a rotary pump of 650 l / min and a turbo pump of 1500 l / sec were constructed.
본 장비의 최고 진공도는 1×10-7Torr이다. 고진공 영역의 진공 측정은 이온 게이지를 사용하였으며, 공정 압력은 T.C 게이지를 사용하여 측정하였다. 실리콘 기판 쪽에는 SiC 재질을 사용한 히터를 부착하여 기판을 1200℃까지 가열하도록 제작하였다.The maximum vacuum of this equipment is 1 × 10 -7 Torr. Vacuum measurement in the high vacuum region was performed using an ion gauge, and process pressure was measured using a TC gauge. A silicon substrate was attached to the silicon substrate to heat the substrate to 1200 ° C.
반응 가스로는 초고순도 질소가스(99.999)와 아르곤가스(99.999)를 사용하였다.Ultra high purity nitrogen gas (99.999) and argon gas (99.999) were used as the reaction gas.
질화알루미늄(AlN) 박막을 제조하기 전에 터보펌프로 1×10-6(Torr)로 챔버의 초기 진공도를 유지시킨 후, 아르곤과 질소가스를 챔버 내에 주입시키면서 표 1과 같은 증착 조건으로 스퍼터링하여 질화알루미늄(AlN) 박막을 형성하였다.Before manufacturing the aluminum nitride (AlN) thin film, the initial vacuum of the chamber was maintained at 1 × 10 −6 (Torr) with a turbopump, and then nitrided by sputtering under the deposition conditions shown in Table 1 while injecting argon and nitrogen gas into the chamber. An aluminum (AlN) thin film was formed.
질화알루미늄(AlN) 박막을 레이라이(Rayleigh)파를 이용한 SAW 가스 센서 소자에 응용하기 위해서는 압전성이 가장 큰 c축 우선 배향성을 가져야 한다.In order to apply an aluminum nitride (AlN) thin film to a SAW gas sensor device using a Rayleigh wave, it must have the c-axis-oriented orientation having the largest piezoelectricity.
여기서, 우선 배향성은 다결정 박막의 증착에 있어서 특정한 결정면이 기판에 평행하게 성장하는 현상을 일컫는 말로써, 미세 구조와 더불어 박막의 물성 및 이를 응용한 소자 제조시에 매우 중요하게 조절되어야 할 재료의 특성이다.Here, the orientation refers to a phenomenon in which a specific crystal plane grows in parallel with the substrate in the deposition of the polycrystalline thin film. In addition to the microstructure, the physical properties of the thin film and the characteristics of the material to be controlled are very important when manufacturing the device using the same. to be.
다음으로, 상기한 과정을 거쳐서, 실리콘 기판 위에 증착된 질화알루미늄(AlN) 박막 위에 IDT 전극을 형성하기 위해 IDT 전극 소재인 알루미늄(Al) 박막을 고주파 마그네트론 스퍼터링 법으로 증착하였다. 이 때의 타겟은 직경 3inch, 순도 99.999인 알루미늄(Al) 타겟을 사용하였고, 초기 진공도 1×10-6(Torr)에서 아르곤 가스를 주입하여 고주파 전력 300W로 스퍼터링하여 약6000Å의 알루미늄(Al) 박막을 증착하였다.Next, in order to form an IDT electrode on the aluminum nitride (AlN) thin film deposited on the silicon substrate, the aluminum (Al) thin film, which is an IDT electrode material, was deposited by a high frequency magnetron sputtering method. At this time, an aluminum (Al) target with a diameter of 3 inches and a purity of 99.999 was used, and an aluminum thin film having a thickness of about 6000 mW was formed by injecting argon gas at an initial vacuum of 1 × 10 -6 (Torr) and sputtering at a high frequency power of 300 W. Was deposited.
그리고, IDT 전극을 형성하기 위한 식각 과정으로, 알루미늄(Al) 이 증착된 기판 상에 감광제(photoresist)를 도포하기 위해 스핀 코터(spin coater)를 사용하였으며, 사용된 감광제는 양성 감광제(AZ-1350)이다.In addition, as an etching process for forming an IDT electrode, a spin coater was used to apply a photoresist on a substrate on which aluminum (Al) was deposited, and the photoresist used was a positive photoresist (AZ-1350). )to be.
초벌구이(Soft bake)는 80℃ 오븐에서 30분 동안 하였으며, 일본 캐논(Canon)사의 PLA 600F 마스크 정렬기(Aligner)를 사용하여 IDT 패턴을 노광하였다. IDT 전극으로 사용된 알루미늄(Al)을 식각용액으로 습식 식각하여 IDT 패턴을 형성하였다.Soft bake was performed in an 80 ° C. oven for 30 minutes, and the IDT pattern was exposed using a PLA 600F mask aligner manufactured by Canon, Japan. Aluminum (Al) used as an IDT electrode was wet etched with an etching solution to form an IDT pattern.
여기서, 박막 표면 탄성파 소자의 전파 속도(v)는 f0·λ로 주어지며, 표면 탄성파 소자의 전파 속도와 IDT의 전극 간격으로부터 동작 주파수가 결정되기 때문에 IDT 전극을 설계할 때에 이를 고려하여 설계하여야 한다.Here, the propagation velocity (v) of the thin film surface acoustic wave element is given by f 0 · λ, and the operating frequency is determined from the propagation speed of the surface acoustic wave element and the electrode spacing of the IDT. do.
그리고, 질소산화물(NOx)과 반응하여 가스를 감지하는 산화텅스텐 소자를 증착하는 조건은 아래의 표 2와 같으며, 대부분의 공정은 IDT 전극 형성 방법과 유사하다.In addition, the conditions for depositing a tungsten oxide device for sensing a gas by reacting with nitrogen oxide (NOx) are shown in Table 2 below, and most processes are similar to the IDT electrode forming method.
여기서, 상기한 실시예에서는 실리콘 기판 위에 질화알루미늄 박막을 형성하고, IDT 전극을 형성한 후에 산화텅스텐 소자를 형성하는 순서를 예로 들어 설명하였으나, 경우에 따라서는 산화텅스텐 소자를 형성한 후에 IDT 전극을 형성하여도 상관없다.Here, in the above-described embodiment, a procedure of forming an aluminum nitride thin film on a silicon substrate, forming an IDT electrode and then forming a tungsten oxide element is described as an example, but in some cases, the IDT electrode is formed after the tungsten oxide element is formed. You may form.
한편, 상기한 제 1실시예에서는 실리콘 기판 위에 질화알루미늄(AlN)을 증착하고, 그 위에 IDT 전극 및 산화텅스텐(WO3) 소자를 증착한 구조를 갖는 것을 설명하였지만, 본 발명의 제 2실시예에서는 도 2에 나타낸 바와 같이, 실리콘 기판 위에 산화규소(SiO2) 또는 질화규소(Si3N4)와 같은 절연 물질을 증착하고, 그 위에 IDT 전극을 형성하고, 다시 그 위에 질화알루미늄(AlN) 압전 박막을 증착하고, 다시 가스감지 소자인 산화텅스텐(WO3)을 증착한 다른 구조의 질소산화물(NOx) 가스 센서를 제시하였다.On the other hand, the first embodiment described above has a structure in which aluminum nitride (AlN) is deposited on a silicon substrate and an IDT electrode and a tungsten oxide (WO 3 ) element are deposited thereon, but the second embodiment of the present invention is described. In Fig. 2, as shown in Fig. 2, an insulating material such as silicon oxide (SiO 2 ) or silicon nitride (Si 3 N 4 ) is deposited on a silicon substrate, an IDT electrode is formed thereon, and an aluminum nitride (AlN) piezoelectric layer is formed thereon. A nitrogen oxide (NOx) gas sensor having a different structure in which a thin film was deposited and then a tungsten oxide (WO 3 ), which is a gas detection device, was deposited.
이와 같은 제 2실시예는 제 1실시예에 비하여 공기 접촉에 의한 잡신호를 제거하는 탁월한 효과가 있는 반면에 제조 시간이 오래 걸리는 단점이 있으며, 제 1실시예는 제조 시간이 짧기 때문에 생산성이 높은 반면에 IDT 전극이 공기와 접촉하여 잡신호가 발생하는 단점이 있다.While the second embodiment has an excellent effect of eliminating a miscellaneous signal due to air contact, compared to the first embodiment, it takes a long time to manufacture, while the first embodiment has high productivity due to short manufacturing time. There is a disadvantage that the IDT electrode is in contact with the air to generate a signal.
또한, NOx 가스 센서를 비롯한 가스 센서는 가스를 감지하는 감지 소자(WO3)에 가스가 응착되어 정확한 가스 감지가 이루어지지 않는 문제점이 있다.In addition, the gas sensor including the NOx gas sensor has a problem that the gas is adhered to the sensing element (WO 3 ) for detecting the gas does not accurately detect the gas.
이를 위하여 가스 감지 소자에 열을 가하여 가스를 증발시켜 주는 히터가 필요하다.To this end, a heater is needed to evaporate the gas by applying heat to the gas sensing element.
이를 위하여, 실리콘 기판의 하부면 즉, 산화텅스텐 질소산화물 감지 센서의 반대편 쪽에 백금(Pt)을 이용하여 증착하여 히터를 형성하였다.To this end, a heater was formed by depositing platinum (Pt) on the lower surface of the silicon substrate, that is, the opposite side of the tungsten oxide oxide sensor.
이 히터의 동작 주기는 가스 감지 주기에 맞추어 동작시키며, 교류 또는 직류 전원을 공급하여 열을 발생시킨다.The operation cycle of the heater operates in accordance with the gas detection cycle, and generates heat by supplying AC or DC power.
상기한 실시예에서는 기판으로 실리콘(100, 111)을 이용한 것을 예로 들어 설명하였지만, 경우에 따라서는 산화알루미늄(Al2O3) 또는 사파이어를 기판으로 이용하여도 된다.In the above-described embodiment, the use of silicon (100, 111) as a substrate has been described as an example, but in some cases, aluminum oxide (Al 2 O 3 ) or sapphire may be used as the substrate.
상기한 바와 같이 제조된 산화질소 가스 센서를 이용하여 질소 산화물을 검출하는 방법은 도 3에 나타낸 바와 같이, 기준 신호 검출용 IDT 전극과 감지 신호 검출용 IDT 전극에 같은 주파수를 갖는 신호 fi를 입력시키면 출력 단자에 각각 fo, fo±Δ신호가 출력된다.In the method for detecting nitrogen oxide using the nitric oxide gas sensor manufactured as described above, as shown in FIG. 3, the signal f i having the same frequency is input to the IDT electrode for reference signal detection and the IDT electrode for detection signal detection. In this case, f o and f o ± Δ signals are output to the output terminals, respectively.
이 때, 감지 신호 검출용 IDT 전극 사이에는 질소 산화물 가스(NOx)와 반응하는 산화텅스텐(WO3)으로 된 산화텅스텐 소자(감지막)이 부착되어 있으므로, 이 산화텅스텐 소자가 질소 산화물(NOx) 가스와 반응하여 질화알루미늄(AlN)으로 된 압전막을 통과 탄성 표면파의 주파수(fΔ)를 변화시켜 주며, 이 변화량(fΔ)은 산화텅스텐 소자에 반응하는 질소 산화물(NOx) 가스의 양에 비례하여 변화한다.At this time, since the tungsten oxide element (sensing film) made of tungsten oxide (WO 3 ) reacts with nitrogen oxide gas (NOx) between the IDT electrodes for detecting the detection signal, the tungsten oxide element is nitrogen oxide (NOx). It gives to the frequency (f Δ) of gas and the reaction through the piezoelectric film of aluminum nitride (AlN) surface acoustic wave changes, the change amount (f Δ) is proportional to the amount of nitrogen oxides (NOx) gas in response to a tungsten oxide element To change.
따라서, 기준 신호 검출용 IDT 전극과 감지 신호 검출용 IDT 전극에서 출력되는 주파수의 차이(fΔ)를 검출하여 파악하면, 정확하게 질소 산화물(NOx) 가스량을 감지할 수 있는 것이다.Therefore, if the difference f Δ of the frequency output from the IDT electrode for reference signal detection and the IDT electrode for detection signal detection is detected and understood, the amount of nitrogen oxide (NOx) gas can be accurately detected.
여기서, 산화텅스텐 소자에 반응하는 질소 산화물(NOx) 가스가 응착되어 감지량에 오차를 발생시키므로, 반드시 주기적으로 히터를 이용하여 산화텅스텐 소자와 반응한 질소산화물(NOx) 가스를 제거시켜 주어야만 항상 정확한 가스량을 측정할 수 있다.Here, since the nitrogen oxide (NOx) gas reacted with the tungsten oxide element is adhered to generate an error in the detection amount, it is always necessary to remove the nitrogen oxide (NOx) gas reacted with the tungsten oxide element periodically by using a heater. The amount of gas can be measured.
상기한 바와 같이 이루어진 본 발명에 따른 질소산화물 가스 센서 및 그 제조 방법은 압전 단결정 대신 질화알루미늄(AlN)의 압전 박막을 사용하여 질소산화물 가스 센서를 제작함으로써, 소형이면서 경량이며, 저가격이고, 외부 환경 변화와 관계없이 항상 정확하게 작동하면서, 극소량(ppb 레벨)까지 감지해 내는 효과를 제공한다.The nitrogen oxide gas sensor and the method for manufacturing the same according to the present invention made as described above are manufactured by using a piezoelectric thin film of aluminum nitride (AlN) instead of a piezoelectric single crystal to produce a nitrogen oxide gas sensor. It always works correctly regardless of change, providing the ability to detect very low levels (ppb levels).
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| US8785924B2 (en) | 2011-12-12 | 2014-07-22 | Korea Institute Of Science And Technology | High-sensitivity transparent gas sensor and method for manufacturing the same |
| KR101526576B1 (en) * | 2008-11-28 | 2015-06-08 | 엘지이노텍 주식회사 | Semiconductor gas sensor |
| US9285332B2 (en) | 2011-12-12 | 2016-03-15 | Korea Institute Of Science And Technology | Low power consumption type gas sensor and method for manufacturing the same |
| KR20210050282A (en) | 2019-10-28 | 2021-05-07 | 한국광기술원 | GaN based Gas Detector Combined Heater and Method for Manufacturing the Same |
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| KR100387174B1 (en) * | 2000-02-02 | 2003-06-11 | 이덕동 | High stability gas sensor using GaN and its Fabrication Method |
| KR100681782B1 (en) * | 2004-03-29 | 2007-02-12 | 성균관대학교산학협력단 | Sensing element for microchemical sensor and manufacturing method using micro piezoelectric driving element |
| KR101025715B1 (en) * | 2009-01-12 | 2011-04-04 | 연세대학교 산학협력단 | Gas detection sensor using SAB element and its detection method |
| KR101333830B1 (en) * | 2012-07-16 | 2013-11-29 | 울산대학교 산학협력단 | Surface acoustic wave humidity sensors including zno nanorods and method for manufacturing the same |
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| KR101526576B1 (en) * | 2008-11-28 | 2015-06-08 | 엘지이노텍 주식회사 | Semiconductor gas sensor |
| US8785924B2 (en) | 2011-12-12 | 2014-07-22 | Korea Institute Of Science And Technology | High-sensitivity transparent gas sensor and method for manufacturing the same |
| US9285332B2 (en) | 2011-12-12 | 2016-03-15 | Korea Institute Of Science And Technology | Low power consumption type gas sensor and method for manufacturing the same |
| KR20210050282A (en) | 2019-10-28 | 2021-05-07 | 한국광기술원 | GaN based Gas Detector Combined Heater and Method for Manufacturing the Same |
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