JPS5879149A - Gas detection element - Google Patents
Gas detection elementInfo
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- JPS5879149A JPS5879149A JP17775781A JP17775781A JPS5879149A JP S5879149 A JPS5879149 A JP S5879149A JP 17775781 A JP17775781 A JP 17775781A JP 17775781 A JP17775781 A JP 17775781A JP S5879149 A JPS5879149 A JP S5879149A
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- Prior art keywords
- metal oxide
- semiconductor
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- oxide semiconductor
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
- G01N27/12—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid
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- Life Sciences & Earth Sciences (AREA)
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- General Health & Medical Sciences (AREA)
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- Investigating Or Analyzing Materials By The Use Of Fluid Adsorption Or Reactions (AREA)
Abstract
Description
【発明の詳細な説明】
この発明はガス検出素子の改良に関するもので、とりわ
けCo 、NH3,C12、H2S等のガスを選択的に
検出しつる素子の改良に関し、毒性ガスの検出や、排ガ
スの組成の検出等に有効なものである。Detailed Description of the Invention The present invention relates to the improvement of gas detection elements, and in particular to the improvement of elements that selectively detect gases such as Co, NH3, C12, H2S, etc. This is effective for composition detection, etc.
現在用いられているガス検出素子には、大別して2つの
ものがある。その1つは酸化触媒による可燃性ガスの接
触燃焼全利用するもので、燃焼熱k 測幅抵抗体の抵抗
値の変化として検出するものである。他の1つは、ガス
の吸脱着による金属酸化物半導体の抵抗値の変化を利用
するもので、信頼性が高いところから広く用いられてい
るものである。Gas detection elements currently in use can be broadly classified into two types. One of them is to fully utilize the catalytic combustion of combustible gas using an oxidation catalyst, and the combustion heat k is detected as a change in the resistance value of a width-measuring resistor. The other method utilizes changes in the resistance value of a metal oxide semiconductor due to adsorption and desorption of gas, and is widely used due to its high reliability.
金属酸化物半導体の抵抗値の変化を利用した素子を用い
て、coや、N H3,Cl 2 、H2S等のガスを
選択的に検出する試みも広く行われている。これらのガ
スに対する感度は、素子の加熱温度を低くすることによ
って、改善できる。しかし素子の加熱温度を下げること
には限度かある。湿度特性の悪化、応答速度の低下、経
時特性の悪化といった問題か生ずるためである。Attempts have also been made to selectively detect gases such as co, NH3, Cl2, H2S, etc. using elements that utilize changes in the resistance value of metal oxide semiconductors. Sensitivity to these gases can be improved by lowering the heating temperature of the element. However, there is a limit to lowering the heating temperature of the element. This is because problems such as deterioration of humidity characteristics, decrease in response speed, and deterioration of characteristics over time may occur.
このような金属酸化物31′導体は、可燃性ガスに対す
る酸化触媒でもある。COや、NH3等の比較的酸化を
受けやすいガスは、金属酸化物半導体の内部へ拡散する
間に除去されてし1つ。これに対して、妨害ガスである
水素やエタノール匍−のガスは酸化を受けにくい。この
ように、金属酸化物半導体がガスへのフィルターとして
機能することは、特開昭50−155292勺等により
、既に知られている。Such a metal oxide 31' conductor is also an oxidation catalyst for combustible gases. Gases that are relatively susceptible to oxidation, such as CO and NH3, are removed during diffusion into the metal oxide semiconductor. On the other hand, interfering gases such as hydrogen and ethanol are less susceptible to oxidation. It is already known from Japanese Unexamined Patent Publication No. 155292/1983 that metal oxide semiconductors function as filters for gases.
フィルター作用から考えると、金属酸化物半導体の厚さ
を小さくすれば、COやNH3等のガスを選択的に検出
しつるはずである。そしてこのためには、アルミナ等の
基体を用いて、半導体膜を支持する他に方法はない。し
かしなから、半導体の熱膨張率と基体のそれとは一般に
一致しない。そして素子は、そのオン・オフのどとvc
熱衝撃にさらされる。このため半導体[漢は基体から剥
離したり、クランクか生じたりする。この傾向は、半導
体膜を薄くする程著しい。半導体と基体との熱膨張率か
一致しないため、CO等のガスに選択性が得られる程度
に、半導体膜を薄くすることは不可能である。Considering the filter effect, if the thickness of the metal oxide semiconductor is made small, gases such as CO and NH3 should be selectively detected. For this purpose, there is no other way than to support the semiconductor film using a base material such as alumina. However, the coefficient of thermal expansion of a semiconductor and that of a substrate generally do not match. And the element has its on/off throat and vc
Exposure to thermal shock. As a result, the semiconductor may peel off from the substrate or crack. This tendency becomes more pronounced as the semiconductor film becomes thinner. Since the thermal expansion coefficients of the semiconductor and the substrate do not match, it is impossible to make the semiconductor film thin enough to obtain selectivity for gases such as CO.
この発明は、金属酸化物半導体に」−力な厚みを持たせ
た1丑、COやNH3C12,I2 S等の低温形ガス
を有利に検出しつる素子を提供すること全目的とする。The overall object of the present invention is to provide an element that can advantageously detect low-temperature gases such as CO, NH3C12, I2S, etc., using a metal oxide semiconductor having a large thickness.
この発明のガス演目」素子は、ガス敏感性金属酸化物半
導体に少くとも一対の電kk接続したものにおいで、前
記金属酸化物半導体の圧電気伝導度を、表向附近の饋」
戊で内部の頭載より大きくせしめ、かつこの表面附近の
領域の厚さを500 /7以下としたものである。The gas-sensitive element of the present invention has at least one pair of electrical connections to a gas-sensitive metal oxide semiconductor to increase the piezoelectric conductivity of the metal oxide semiconductor ostensibly in the vicinity of the surface.
The hole is made larger than the internal head, and the thickness of the area near the surface is 500/7 or less.
ここに金属酸化物半導体としては、ガスの吸脱着により
抵抗値が変化するものを広く用いれは良く、5n02.
TiO2、In203Fe203.ZnO+CoO+N
iO,MgFe2O4等を用いることかできる。金属酸
化物半導体には種々の添加物、例えば感度を向」二させ
るための貴金属触媒、クラックの防止や機械的強度の向
上のための、アルミナ等の骨相や不定形シリカ等の結合
剤、全加えても良い。As the metal oxide semiconductor, those whose resistance value changes due to adsorption and desorption of gas are widely used, and 5n02.
TiO2, In203Fe203. ZnO+CoO+N
iO, MgFe2O4, etc. can be used. Metal oxide semiconductors contain various additives, such as noble metal catalysts to improve sensitivity, binders such as alumina and amorphous silica to prevent cracks and improve mechanical strength, and metal oxide semiconductors. You can also add it.
表面附近と内部とで金属酸化物21を導体の圧電気伝導
度を変化させる手段としては、原子価制御、あるいは半
導体の焼成条件の制御等によるキャリヤー数の制御、等
ゲ用いれば良い。原子価制御によす!14100電気伝
導度を高める例としては、5n02への5b203の添
加、Fe2O3へのT + 02 +ZnO2へのAl
2O3,CoOへのI−i20 、N ioへのL i
20の添加等がある。逆の例としては、5n02へのC
r2O3の添加、ZnOへのしI20.NiOへのCr
2O3の?A加等がある。焼成条件の制御による圧電気
伝導度の制御は以下のようにして行われる。As a means for changing the piezoelectric conductivity of the metal oxide 21 near the surface and inside the conductor, valence control, control of the number of carriers by controlling the firing conditions of the semiconductor, etc. may be used. Good luck with valence control! Examples of increasing the electrical conductivity of 14100 include the addition of 5b203 to 5n02, T + 02 to Fe2O3 + Al to ZnO2.
2O3, I-i20 to CoO, Li to Nio
There are 20 additions, etc. For the opposite example, C to 5n02
Addition of r2O3 to ZnO I20. Cr to NiO
2O3's? There are A additions, etc. The piezoelectric conductivity is controlled by controlling the firing conditions as follows.
半導体の焼成条件を高める程、その結晶中の欠陥は減少
し、電気伝導度も減少する。この性質を利用し、焼成温
度を選択することにより、半導体の電気伝導度を制御す
ることかできる。そして上記の手法を用い、金属酸化物
半導体の表面附近と内部との圧電気伝導度を異らしめる
。具体的には、■ 表面附近に圧電気伝導度を高めた材
料を用いる、
■ 内部に圧電気伝導度を小さくした材料を用いる、
■ 両者を併用する、
等によれば良い。The higher the firing conditions for a semiconductor, the fewer defects in its crystal and the lower the electrical conductivity. By utilizing this property and selecting the firing temperature, the electrical conductivity of the semiconductor can be controlled. Then, using the above method, the piezoelectric conductivity near the surface of the metal oxide semiconductor and inside the metal oxide semiconductor are made different. Specifically, the following methods may be used: (1) Use a material with high piezoelectric conductivity near the surface, (2) Use a material with low piezoelectric conductivity inside, (2) Use both in combination.
なお特に限定する意味ではないが、5n02に用いる場
合に、既に焼成を終えたSnO2に錫の塩化物を加える
ことはさけることが望捷しい。5nCI!2等の添加に
より、5n02の圧電気伝導度は増大するか、添加され
た5nC12の焼成か不十分なため、経時的侶頓性か低
いからである。Although not particularly limited, when used in 5n02, it is desirable to avoid adding tin chloride to already fired SnO2. 5nCI! This is because either the piezoelectric conductivity of 5n02 increases due to the addition of 5nC12, or the sintering of the added 5nC12 is insufficient, resulting in low stagnation over time.
ガス検出素子の形状には、公知のものを広く用いること
ができ、金属酸化物半導体の厚さも小さくする1必凋は
ない。第1図および第2図に示すような、既存の形状を
その捷ま用いることかできる。A wide variety of known shapes can be used for the shape of the gas detection element, and there is no necessity to reduce the thickness of the metal oxide semiconductor. Existing shapes, such as those shown in FIGS. 1 and 2, can be used by cutting them.
金属酸化物半導体のうち、圧電気伝導度を内部より高く
すべき部分を、表面から500 ti以下としたのは、
これ以上ではCOやNH3への感度が低下するからであ
る。この部分を蒸着等によって形成する場合の厚さは1
μ程度でもよい。The reason why the part of the metal oxide semiconductor where the piezoelectric conductivity should be higher than the inside is set to 500 ti or less from the surface is as follows.
This is because the sensitivity to CO and NH3 decreases if the temperature exceeds this range. When this part is formed by vapor deposition etc., the thickness is 1
It may be about μ.
この発明のガス検出素子の動作は次のように考えること
ができる。The operation of the gas detection element of this invention can be considered as follows.
ガス検出素子の電気伝導度は、表面付近の金属酸化物半
導体によって定寸るようになる。そして表面付近では、
COやNH3+H2S等のガスも、半導体の酸化活性の
影響を受けない。フィルター活性の影響を受ける半導体
の内部の電気伝導度は、素子の出力にほとんど影響しな
い。したがって金属酸化物半導体の表面付近の電気伝導
度を内部より高めておくことにより、CO、N I3等
のガスを高感度で検出することかできる。The electrical conductivity of the gas detection element is determined by the metal oxide semiconductor near the surface. And near the surface,
Gases such as CO and NH3+H2S are also not affected by the oxidation activity of semiconductors. The electrical conductivity inside the semiconductor, which is affected by filter activity, has little effect on the output of the device. Therefore, by increasing the electrical conductivity near the surface of the metal oxide semiconductor from the inside, gases such as CO and NI3 can be detected with high sensitivity.
以1ζに谷実雁例について説、明する。In the following, I will explain and explain the example of Tanimi-Gan.
5nC14水溶液ya=NHsて中和り、 S n (
OH)4の沈澱分母る。沈澱を水洗後、300°Cて2
時間の1次・焼成を行う。1次・暁成後の5n02ケ2
次焼成(600℃×2時間)L2、粉砕する。この5n
02を以下5nO2(イ)として示す。なお以下のすへ
ての材料について、2次焼成後に粉砕を行うものとし、
その旨の説り1を省略する。Neutralize with 5nC14 aqueous solution ya=NHs, S n (
OH) 4 precipitate denominator. After washing the precipitate with water, heat at 300°C for 2
Perform the first stage and firing of the time. 5n02ke2 after 1st Akatsuki
Next firing (600°C x 2 hours) L2 and pulverization. This 5n
02 is hereinafter referred to as 5nO2 (a). All of the following materials shall be pulverized after secondary firing.
I will omit explanation 1 to that effect.
1次・暁1戊後の5n02100重量部π08重用部の
5l)203を添加し、600°Cて2時間焼成する。5l) 203 of 5n02100 parts by weight π08 parts by weight after the 1st stage and dawn was added and baked at 600°C for 2 hours.
この・焼成、過程でアンチモンはV測寸で酸化され、5
n02の原子価制御か行われる。こ才]によってSnO
2のIt電気伝導度は5n02(A)の約50倍に増す
。このものk S n 02 S b203として示
す。In this firing process, antimony is oxidized with V measurement, and 5
Valence control of n02 is performed. by SnO
The It electrical conductivity of 2 is increased approximately 50 times that of 5n02(A). This is shown as k S n 02 S b203.
1次焼成後のSn 02100重i1’c Mi’n
Crc13水溶液(C+;5Q3換鐘で0.5重11部
)を加え、600℃で2時間焼成する。これによって比
電気伝導度は5nO2(A)の約1000分の11で低
下する。このものを、S n 02−Cr 203 と
して示す。Sn 02100 weight i1'c Mi'n after primary firing
A Crc13 aqueous solution (C+; 0.5 weight and 11 parts with 5Q3 exchange) is added and baked at 600°C for 2 hours. This reduces the specific electrical conductivity by about 11/1000 of 5 nO2 (A). This is designated as S n 02-Cr 203 .
ZnCj?2水溶液をNaOH水で中和し、水洗をくり
返してZn(01()2の沈澱を得る。この沈澱に、大
気中での300°Cで2時間の1次・焼成を腋した後に
、大気中で500℃に2時間加熱し2次焼成とする。こ
のZn0(z以下KZnO(A) として示す。ZnCj? The aqueous solution of Zn(01()2) is neutralized with NaOH water and washed with water repeatedly to obtain a precipitate of Zn(01()2. This precipitate is subjected to primary firing for 2 hours at 300°C in the atmosphere, and then exposed to the atmosphere. The product is heated for 2 hours at 500° C. for secondary firing.
1次焼成、後のZn0100重I■部に、1重用部のA
、 l! 203を添加し、500°Cで2時間・焼成
する。After primary firing, add A of 1 layer to 1 layer of Zn0100 layer I.
, l! Add 203 and bake at 500°C for 2 hours.
これによって比電気伝導度はZ n 0(A)の約30
倍に増大する。このものfZnOAI’?203として
示す。As a result, the specific electrical conductivity is approximately 30 of Z n 0 (A).
increase twice. Is this thing fZnOAI'? 203.
1次焼成後のZnO100重量部に1重用都のLi20
i加え500°Cで2時間・暁戎する。これによって比
電気伝導度はZn0(イ)の1000分の1以下に低下
する。このもの’r ZnO−L i20として示す。Add 1 layer of Li20 to 100 parts by weight of ZnO after primary firing
Add water and heat at 500°C for 2 hours. As a result, the specific electrical conductivity decreases to 1/1000 or less of Zn0 (a). This is designated as 'rZnO-L i20.
1次焼成後のZnOk酸素中1 (1000Cで2時間
・暁吠する。このもののIt電気伝導度はZ n 0(
A)の約1/H1である。このもの全ZnQ[F])と
して示す。After the primary firing, ZnOk was heated in oxygen for 2 hours at 1000 C. The electrical conductivity of this material was Z n 0 (
It is approximately 1/H1 of A). This is shown as total ZnQ[F]).
第1図および第2図に示す構造を用いる。図において(
1) 、 (2)はコイル状の白金電(竜で、いずれも
ヒークケ兼ねさせる。(3)は金属酸化物半導体の内部
の部分で、その厚さは2mmである。金属酸化物半導体
(3)ニより、電+1f(1) 、 (2)の約’l’
Dkおおうようにする。(4)は金属酸化物半導体の表
面部分て、金属酸化物半導体(3) 、、、1.ニーに
所定の厚さに塗布[7たものである。なお塗布に代えて
、浸偵等乞用いかも良い。金属酸化物半導体(4)の厚
さは、一様でなくても良い。一様の厚さに塗布すること
は困難であるし、厚さにむらが存在しても素子の特性に
あ捷り影響しないからである。The structure shown in FIGS. 1 and 2 is used. In the figure (
1) and (2) are coil-shaped platinum electrodes, which also serve as heat shields. (3) is the internal part of the metal oxide semiconductor, and its thickness is 2 mm. ) from d, electric +1f (1), about 'l' of (2)
Cover Dk. (4) is the surface part of the metal oxide semiconductor, metal oxide semiconductor (3), 1. Apply it to the knee to a predetermined thickness [7]. Note that instead of applying it, you may use a method such as a spy. The thickness of the metal oxide semiconductor (4) may not be uniform. This is because it is difficult to apply the coating to a uniform thickness, and even if there is unevenness in the thickness, it does not affect the characteristics of the device.
第3図に素子の構造の変形例金示す。図において、(]
1)はlt電気伝導度の低い金属酸化物半導体の内部部
分であり、cのは金属酸化物半導体の表面部Q、 l
mmである。0■、04)は白金の厚膜電極、θ0は銀
−バラジクム等の厚嘆ヒータである。この場合、電ft
(13、(14)やヒータ0つ中のガラス成分等による
半導体01)の劣化は考慮する必要がない。半導体01
)の電気伝導度は小さくしであるからである。この構造
の素子の特性は、第1図および第2図のものと同様であ
る。FIG. 3 shows a modified example of the structure of the element. In the figure, (]
1) is the internal part of the metal oxide semiconductor with low electrical conductivity, c is the surface part Q of the metal oxide semiconductor, and l
It is mm. 0■, 04) are thick film electrodes made of platinum, and θ0 is a thick heater made of silver-baladicum or the like. In this case, electric ft
There is no need to consider the deterioration of semiconductor 01 due to (13, (14) or the glass component in heater 0). Semiconductor 01
) has a small electrical conductivity. The characteristics of the device of this structure are similar to those of FIGS. 1 and 2.
検1]」ガスの代表例として、Co 50ppmlえら
び、清浄空気中との抵抗値の比、CC0501)T)中
での抵抗値を測定した。隋書ガスの代表例としてH2を
えらび、 C050ppmと同一の1重度を与えるH2
2重(以下H2等価濃度という)を求めた。Test 1] As a representative example of a gas, 50 ppml of Co was selected, and the resistance value ratio with that in clean air and the resistance value in CC0501)T) were measured. H2 is selected as a representative example of Suishu gas, and H2 gives a weight of 1, which is the same as C050ppm.
Double (hereinafter referred to as H2 equivalent concentration) was determined.
測定には第1図および第2図の素子を用い、20°C1
65%RH中で実験を行った。素子の加1度は5n02
を用いる場合に200°C,ZnOを用いる場合250
°Cとした。For measurements, the elements shown in Figures 1 and 2 were used, and the temperature was 20°C1.
Experiments were conducted in 65% RH. The addition degree of the element is 5n02
200°C when using ZnO, 250°C when using ZnO
It was set to °C.
結果を表に示す。The results are shown in the table.
表において、組成の141−は表面部分の組成を、下欄
は内部のものを示す。表面部分の厚さを単に「厚さ」と
して示す。′8I8た※印のものは、比較のだめのもの
である。In the table, 141- of the composition indicates the composition of the surface portion, and the lower column indicates the composition of the inside. The thickness of the surface portion is simply indicated as "thickness". '8I8Those marked with * are useless for comparison.
以1−に説りjしたように、この発明によれば、金属酸
化物半導体に十分な厚さをもたせたま捷、Co 、 N
H3、C・j?2. H2S等のガスヲ高感度で検11
」スることかできる。As explained in 1-1, according to the present invention, a metal oxide semiconductor having a sufficient thickness, Co, N, etc.
H3, C.j? 2. Highly sensitive detection of gases such as H2S11
” I can do it.
第1図は、実施例の1子の−)■切り欠き図、第2図は
第1図のA−A′方向断面図である。第3図は11しの
実施例の断面図である。
(1,) 、 (2) 、 01 、 (14)・・電
極、(3) 、 (]υ・・・金属酸化物半導体の内部
部分、(4) 、 0の°金属酸化物半導体の表面部分
。
特W「出願人 フイガロ技研株式会r1−代表者 千
葉 瑛
第3図 、2FIG. 1 is a cutaway view of one child of the embodiment, and FIG. 2 is a sectional view taken along the line A-A' in FIG. 1. FIG. 3 is a sectional view of the eleventh embodiment. (1,), (2), 01, (14)...electrode, (3), (]υ...inner part of metal oxide semiconductor, (4), 0° surface part of metal oxide semiconductor Special W "Applicant: Figaro Giken Co., Ltd. r1 - Representative: Ei Chiba Figure 3, 2
Claims (1)
物1′導体に、少くとも一対の電極を接続したガス検出
素子において、前記金属酸化物21′導体の比電気伝導
度を、表面附近の領域で内部の領域より大きくせしめ、
かつこの表面附近の領域の厚さを500μ以下としたこ
とを特徴とするガス検出素子。1. In a gas detection element in which at least one pair of electrodes is connected to a bulk metal oxide 1' conductor whose resistance value changes depending on the gas, the specific electrical conductivity of the metal oxide 21' conductor near the surface is measured. Make the area larger than the inner area,
A gas detection element characterized in that the thickness of the region near the surface is 500μ or less.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP17775781A JPS5879149A (en) | 1981-11-05 | 1981-11-05 | Gas detection element |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP17775781A JPS5879149A (en) | 1981-11-05 | 1981-11-05 | Gas detection element |
Publications (1)
Publication Number | Publication Date |
---|---|
JPS5879149A true JPS5879149A (en) | 1983-05-12 |
Family
ID=16036589
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP17775781A Pending JPS5879149A (en) | 1981-11-05 | 1981-11-05 | Gas detection element |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS5879149A (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0114310A2 (en) * | 1982-12-25 | 1984-08-01 | Nohmi Bosai Kogyo Co., Ltd. | Carbon monoxide sensing element and process for manufacturing it |
JPH03264840A (en) * | 1990-03-15 | 1991-11-26 | Fuji Electric Co Ltd | Chlorine dioxide meter |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5633535A (en) * | 1979-08-22 | 1981-04-04 | Siemens Ag | Selective gas sensor |
-
1981
- 1981-11-05 JP JP17775781A patent/JPS5879149A/en active Pending
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5633535A (en) * | 1979-08-22 | 1981-04-04 | Siemens Ag | Selective gas sensor |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0114310A2 (en) * | 1982-12-25 | 1984-08-01 | Nohmi Bosai Kogyo Co., Ltd. | Carbon monoxide sensing element and process for manufacturing it |
JPH03264840A (en) * | 1990-03-15 | 1991-11-26 | Fuji Electric Co Ltd | Chlorine dioxide meter |
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