JP3000726B2 - Gas sensor - Google Patents
Gas sensorInfo
- Publication number
- JP3000726B2 JP3000726B2 JP3141273A JP14127391A JP3000726B2 JP 3000726 B2 JP3000726 B2 JP 3000726B2 JP 3141273 A JP3141273 A JP 3141273A JP 14127391 A JP14127391 A JP 14127391A JP 3000726 B2 JP3000726 B2 JP 3000726B2
- Authority
- JP
- Japan
- Prior art keywords
- gas sensor
- tin oxide
- oxide film
- gas
- palladium
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- KDLHZDBZIXYQEI-UHFFFAOYSA-N palladium Substances [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 claims description 31
- XOLBLPGZBRYERU-UHFFFAOYSA-N tin dioxide Chemical compound O=[Sn]=O XOLBLPGZBRYERU-UHFFFAOYSA-N 0.000 claims description 15
- 229910001887 tin oxide Inorganic materials 0.000 claims description 15
- 229910052763 palladium Inorganic materials 0.000 claims description 11
- 239000000758 substrate Substances 0.000 claims description 11
- 239000007789 gas Substances 0.000 description 24
- 239000010408 film Substances 0.000 description 22
- 238000000034 method Methods 0.000 description 6
- 229910000510 noble metal Inorganic materials 0.000 description 6
- 239000003054 catalyst Substances 0.000 description 5
- 230000035945 sensitivity Effects 0.000 description 5
- 238000004544 sputter deposition Methods 0.000 description 5
- 238000004833 X-ray photoelectron spectroscopy Methods 0.000 description 4
- 229910044991 metal oxide Inorganic materials 0.000 description 4
- 150000004706 metal oxides Chemical class 0.000 description 4
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 3
- 229910052737 gold Inorganic materials 0.000 description 3
- 239000010931 gold Substances 0.000 description 3
- 230000000873 masking effect Effects 0.000 description 3
- 238000001771 vacuum deposition Methods 0.000 description 3
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 2
- 239000005977 Ethylene Substances 0.000 description 2
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 2
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 229910006404 SnO 2 Inorganic materials 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 229940117927 ethylene oxide Drugs 0.000 description 1
- 239000002932 luster Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- 150000003606 tin compounds Chemical class 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
- 239000011787 zinc oxide Substances 0.000 description 1
Landscapes
- Investigating Or Analyzing Materials By The Use Of Fluid Adsorption Or Reactions (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は、ガスセンサに関する。
更に詳しくは、ガス感応性膜として酸化錫膜を用いたガ
スセンサに関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas sensor.
More specifically, the present invention relates to a gas sensor using a tin oxide film as a gas-sensitive film.
【０００２】[0002]
【従来の技術】従来から、ガスセンサのガス感応性膜と
して酸化錫膜、酸化亜鉛膜などの金属酸化物焼結体膜が
実際に用いられている。これらのガス感応性膜にあって
は、それの感度向上のため、一般に白金やパラジウムな
どの貴金属触媒が添加されて用いられている。ところ
で、従来の金属酸化物焼結体ガスセンサにあっては、貴
金属触媒を焼結体全体に添加しているため、すべての貴
金属触媒が有効にガス検知に作用している訳ではない。
また、金属酸化物焼結体表面に存在する貴金属触媒は、
高温条件下の大気中に放置した場合、酸化、凝集などを
起こして経時的安定性を損なわせ、それがガスセンサの
出力の経時的変化をひき起こす原因ともなっている。2. Description of the Related Art Conventionally, metal oxide sintered films such as tin oxide films and zinc oxide films have been actually used as gas-sensitive films for gas sensors. These gas-sensitive films are generally used by adding a noble metal catalyst such as platinum or palladium in order to improve the sensitivity. By the way, in the conventional metal oxide sintered body gas sensor, since the noble metal catalyst is added to the whole sintered body, not all the noble metal catalysts effectively act on gas detection.
The noble metal catalyst present on the surface of the metal oxide sintered body is
If left in the air under high temperature conditions, oxidation, aggregation and the like are caused to impair the stability over time, which also causes the output of the gas sensor to change over time.
【０００３】[0003]
【発明が解決しようとする課題】本発明の目的は、高温
条件下の大気中に放置した場合にあっても、経時的安定
性を損なわせない、貴金属触媒添加金属酸化物焼結体ガ
スセンサを提供することにある。SUMMARY OF THE INVENTION An object of the present invention is to provide a noble metal catalyst-added sintered metal oxide gas sensor which does not impair the stability over time even when left in the air under high temperature conditions. To provide.
【０００４】[0004]
【課題を解決するための手段】かかる本発明の目的は、
絶縁性基板上に形成させた一組の電極を覆う酸化錫膜を
形成させたガスセンサにおいて、酸化錫膜の形成に先立
って、電極形成部分以外の絶縁性基板上に、Pd/(Pd＋S
n)の原子数比で示される表面添加率として1〜50%の割合
となる量のパラジウムを予め添加したガスセンサによっ
て達成される。SUMMARY OF THE INVENTION The object of the present invention is as follows.
In a gas sensor in which a tin oxide film is formed to cover a pair of electrodes formed on an insulating substrate, prior to the formation of the tin oxide film, Pd / (Pd + S
This is achieved by a gas sensor in which palladium is added in advance in an amount of 1 to 50% as a surface addition rate indicated by the atomic ratio of n).
【０００５】絶縁性基板上に形成させた一組の電極形成
部分をマスキングした後、その部分を除く絶縁性基板上
に、真空蒸着法、スパッタリング法などによりパラジウ
ムを添加する。それの添加量は、膜厚モニタにより制御
されるが、Pd/(Pd＋Sn)の原子数比で示される表面添加
率として1〜50%の割合となる量である。After masking a set of electrode forming portions formed on the insulating substrate, palladium is added to the insulating substrate excluding the portions by a vacuum deposition method, a sputtering method, or the like. The amount of addition is controlled by a film thickness monitor, and is an amount that gives a ratio of 1 to 50% as a surface addition rate represented by an atomic ratio of Pd / (Pd + Sn).
【０００６】即ち、絶縁性基板上のパラジウムは不連続
層として形成され、従ってその不連続部分にはその後酸
化錫膜が形成されることになる。このときの表面添加率
が１〜50%、好ましくは10〜20%の割合となる量のパラジ
ウムが予め添加され、これ以上の割合でのパラジウムの
添加は、かえってガス感度を低下させる。That is, palladium on the insulating substrate is formed as a discontinuous layer, and a tin oxide film is subsequently formed on the discontinuous portion. At this time, palladium is added in advance in such an amount that the surface addition ratio becomes 1 to 50%, preferably 10 to 20%, and the addition of palladium at a higher ratio rather lowers the gas sensitivity.
【０００７】その後、マスキングを除去した電極形成部
分およびパラジウムの不連続層をも覆うように、絶縁性
基板を一様に覆う酸化錫膜の形成が行われる。Thereafter, a tin oxide film is formed so as to uniformly cover the insulating substrate so as to cover the electrode-formed portion from which the mask has been removed and the discontinuous palladium layer.
【０００８】一般に約500〜2000Åの膜厚で形成される
酸化錫膜の形成は、真空蒸着法、スパッタリング法など
により金属錫膜を形成させた後酸化処理する方法、金属
錫の酸素による反応性スパッタリングによる方法、金属
光沢を有する有機錫化合物プラズマ重合膜を酸化処理す
る方法(特開昭63-261,148号公報)などによって行われ
る。In general, a tin oxide film having a thickness of about 500 to 2000 ° is formed by a method of forming a metal tin film by a vacuum deposition method, a sputtering method and the like, followed by an oxidation treatment, and a reaction of the metal tin with oxygen. It is carried out by a method of sputtering, a method of oxidizing an organic tin compound plasma polymerized film having a metallic luster (Japanese Patent Application Laid-Open No. 63-261,148), or the like.
【０００９】[0009]
【発明の効果】ガス感応性膜として酸化錫膜を形成させ
たガスセンサにおいて、酸化錫膜と接する絶縁性基板面
に特定割合の表面添加率でパラジウムを添加することに
より、高温時における経時的安定性を向上させたガスセ
ンサを得ることができる。また、表面添加率の制御、換
言すればガス感度の制御も容易である。このガスセンサ
は、エチレン、一酸化炭素などのガスの検知に有効に用
いられる。更に、添加される貴金属触媒は、そのすべて
がガス検知に有効に用いられる。As described above, in a gas sensor having a tin oxide film formed as a gas-sensitive film, palladium is added at a specific rate to the surface of the insulating substrate in contact with the tin oxide film, thereby stabilizing with time at high temperatures. A gas sensor with improved performance can be obtained. Further, it is easy to control the surface addition rate, in other words, to control the gas sensitivity. This gas sensor is effectively used for detecting gases such as ethylene and carbon monoxide. Further, all of the noble metal catalysts to be added are effectively used for gas detection.
【００１０】[0010]
【実施例】次に、実施例について本発明を説明する。Next, the present invention will be described with reference to examples.
【００１１】比較例 一組の金電極を形成させたアルミナ基板上に、スパッタ
リング法により、膜厚約1000Åの酸化錫膜を形成させ
た。その酸化錫膜上に、真空蒸着法によりパラジウムを
蒸着させ、表面添加率が20%の割合でPdを蒸着させた。P
d添加率は、ESCAにより測定され、測定されたESCAの分
析深さは数10Å程度と浅く、またESCAでSnも検出される
ことから、下地であるSnO2も表面に露出していることを
示しており、即ちPdによって表面全体が覆われていない
ことを物語っている。Comparative Example A tin oxide film having a thickness of about 1000 ° was formed by a sputtering method on an alumina substrate on which a pair of gold electrodes had been formed. Palladium was deposited on the tin oxide film by a vacuum deposition method, and Pd was deposited at a surface addition ratio of 20%. P
d The addition ratio was measured by ESCA, and the measured analysis depth of ESCA was as small as several tens of millimeters, and since Sn was detected by ESCA, it was confirmed that the underlying SnO 2 was also exposed on the surface. , Indicating that the entire surface is not covered by Pd.
【００１２】実施例 一組の金電極を形成させたアルミナ基板上に、金電極形
成部分のマスキングを行った後、真空蒸着法により、表
面添加率が20%の割合となる量のパラジウムを蒸着させ
た。マスキングを除去した後、スパッタリング法によ
り、膜厚約1000Åの酸化錫膜を形成させた。EXAMPLE After masking a gold electrode forming portion on an alumina substrate having a pair of gold electrodes formed thereon, palladium was vapor-deposited by vacuum vapor deposition so as to have a surface addition ratio of 20%. I let it. After removing the masking, a tin oxide film having a thickness of about 1000 ° was formed by a sputtering method.
【００１３】このようにして、Ｘ線光電子分光法により
測定した表面添加率が20%のPdを添加した酸化錫膜を有
する、実施例および比較例のガスセンサについて、エチ
レン1000ppmに対するガス感度を測定した。測定に際し
ては、絶縁性基板裏面側に設けられた薄膜ヒータにより
センサ素子を250℃、300℃、350℃または400℃に加熱
し、4時間経過後の抵抗値を空気中での抵抗値Ｒairとし
て測定し、また被検ガス下での抵抗値をＲgasとして測
定し、両者の比Ｒair/Ｒgasをガス感度として算出し
た。As described above, the gas sensitivities of the gas sensors of Examples and Comparative Examples having a tin oxide film doped with Pd having a surface addition rate of 20% as measured by X-ray photoelectron spectroscopy were measured with respect to 1000 ppm of ethylene. . At the time of measurement, the sensor element was heated to 250 ° C, 300 ° C, 350 ° C or 400 ° C by a thin film heater provided on the back side of the insulating substrate, and the resistance value after 4 hours was taken as the resistance value Rair in air. The resistance was measured under the test gas as Rgas, and the ratio Rair / Rgas of the two was calculated as gas sensitivity.
【００１４】得られた結果は、次の表に示される。 The results obtained are shown in the following table.
Claims (1)
覆う酸化錫膜を形成させたガスセンサにおいて、酸化錫
膜の形成に先立って、電極形成部分以外の絶縁性基板上
に、Pd/(Pd＋Sn)の原子数比で示される表面添加率とし
て1〜50%の割合となる量のパラジウムを予め添加したガ
スセンサ。In a gas sensor in which a tin oxide film covering a pair of electrodes formed on an insulating substrate is formed, prior to forming the tin oxide film, Pd is formed on the insulating substrate other than the electrode forming portion. A gas sensor in which palladium is added in advance in an amount of 1 to 50% as a surface addition rate represented by an atomic ratio of / (Pd + Sn).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3141273A JP3000726B2 (en) | 1991-05-17 | 1991-05-17 | Gas sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3141273A JP3000726B2 (en) | 1991-05-17 | 1991-05-17 | Gas sensor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH04343061A JPH04343061A (en) | 1992-11-30 |
| JP3000726B2 true JP3000726B2 (en) | 2000-01-17 |
Family
ID=15288059
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3141273A Expired - Fee Related JP3000726B2 (en) | 1991-05-17 | 1991-05-17 | Gas sensor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3000726B2 (en) |
-
1991
- 1991-05-17 JP JP3141273A patent/JP3000726B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH04343061A (en) | 1992-11-30 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |