JPH04127047A - Gas sensor - Google Patents
Gas sensorInfo
- Publication number
- JPH04127047A JPH04127047A JP23969190A JP23969190A JPH04127047A JP H04127047 A JPH04127047 A JP H04127047A JP 23969190 A JP23969190 A JP 23969190A JP 23969190 A JP23969190 A JP 23969190A JP H04127047 A JPH04127047 A JP H04127047A
- Authority
- JP
- Japan
- Prior art keywords
- thin film
- metal oxide
- semiconductor thin
- oxide semiconductor
- gas
- 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.)
- Pending
Links
- 239000010409 thin film Substances 0.000 claims abstract description 75
- 239000004065 semiconductor Substances 0.000 claims abstract description 46
- 229910044991 metal oxide Inorganic materials 0.000 claims abstract description 41
- 150000004706 metal oxides Chemical class 0.000 claims abstract description 41
- 239000010408 film Substances 0.000 claims description 27
- 239000000758 substrate Substances 0.000 claims description 11
- 239000002131 composite material Substances 0.000 claims description 2
- 230000035945 sensitivity Effects 0.000 abstract description 9
- 238000000137 annealing Methods 0.000 abstract description 7
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 abstract description 4
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 abstract description 4
- 230000000694 effects Effects 0.000 abstract description 4
- 229910052718 tin Inorganic materials 0.000 abstract description 4
- 230000032683 aging Effects 0.000 abstract description 3
- 230000008018 melting Effects 0.000 abstract description 3
- 238000002844 melting Methods 0.000 abstract description 3
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 abstract description 2
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 abstract description 2
- 229910052681 coesite Inorganic materials 0.000 abstract description 2
- 229910052906 cristobalite Inorganic materials 0.000 abstract description 2
- 239000000377 silicon dioxide Substances 0.000 abstract description 2
- 235000012239 silicon dioxide Nutrition 0.000 abstract description 2
- 229910052682 stishovite Inorganic materials 0.000 abstract description 2
- 229910052719 titanium Inorganic materials 0.000 abstract description 2
- 239000010936 titanium Substances 0.000 abstract description 2
- 229910052905 tridymite Inorganic materials 0.000 abstract description 2
- 229910052725 zinc Inorganic materials 0.000 abstract description 2
- 239000011701 zinc Substances 0.000 abstract description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 abstract 1
- 150000001875 compounds Chemical group 0.000 abstract 1
- 229910052593 corundum Inorganic materials 0.000 abstract 1
- 239000011135 tin Substances 0.000 abstract 1
- 229910001845 yogo sapphire Inorganic materials 0.000 abstract 1
- 239000007789 gas Substances 0.000 description 46
- 230000007423 decrease Effects 0.000 description 7
- 239000000463 material Substances 0.000 description 7
- 238000000034 method Methods 0.000 description 7
- 239000013078 crystal Substances 0.000 description 6
- XOLBLPGZBRYERU-UHFFFAOYSA-N tin dioxide Chemical compound O=[Sn]=O XOLBLPGZBRYERU-UHFFFAOYSA-N 0.000 description 6
- 229910001887 tin oxide Inorganic materials 0.000 description 6
- 238000010438 heat treatment Methods 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 4
- 229910001882 dioxygen Inorganic materials 0.000 description 4
- 238000001704 evaporation Methods 0.000 description 4
- 230000008020 evaporation Effects 0.000 description 4
- 239000011230 binding agent Substances 0.000 description 3
- 238000001179 sorption measurement Methods 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- 239000012528 membrane Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 230000004043 responsiveness Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052793 cadmium Inorganic materials 0.000 description 1
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000000550 effect on aging Effects 0.000 description 1
- 229910052738 indium Inorganic materials 0.000 description 1
- APFVFJFRJDLVQX-UHFFFAOYSA-N indium atom Chemical compound [In] APFVFJFRJDLVQX-UHFFFAOYSA-N 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 238000003475 lamination Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
- 230000035882 stress Effects 0.000 description 1
- 230000002123 temporal effect Effects 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
- 238000007738 vacuum evaporation Methods 0.000 description 1
Landscapes
- Investigating Or Analyzing Materials By The Use Of Fluid Adsorption Or Reactions (AREA)
- Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
Abstract
Description
【発明の詳細な説明】
〔技術分野〕
本発明は、雰囲気中にガスが存在することを検知するガ
スセンサに関するものである。DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a gas sensor that detects the presence of gas in an atmosphere.
ガス感応物質として金属酸化物半導体を用い、（ｉ）そ
の金属酸化物半導体裏面に電極及び絶縁膜を介してヒー
ター膜を設け、あるいは（ｔ）その金属酸化物半導体内
部に電極及び電極をかねたヒーター、コイルを設け、そ
れらヒーター膜及び又はヒーターコイルによって加熱さ
れた金属酸化物半導体の抵抗値が表面でのガス吸着によ
って変化することを利用したガスセンサは知られている
。A metal oxide semiconductor is used as a gas-sensitive substance, and (i) a heater film is provided on the back surface of the metal oxide semiconductor via an electrode and an insulating film, or (t) an electrode and an electrode are provided inside the metal oxide semiconductor. Gas sensors are known that are provided with a heater and a coil and utilize the fact that the resistance value of a metal oxide semiconductor heated by the heater film and/or the heater coil changes due to gas adsorption on the surface.
このガスセンサの代表的な一つは薄膜ガスセンサであり
、その概略は、第１図（イ）、（ロ）に示したように、
耐熱性基板１上にヒーター膜２が形成され、その上に絶
縁膜３を介して電極４１゜４２及びガス感応膜５１が形
成された構造を呈したものである。耐熱性基板１が導電
性の場合はヒ−ター膜との間に絶縁膜を形成する必要が
ある。A typical example of this gas sensor is a thin film gas sensor, the outline of which is shown in Figures 1 (a) and (b).
It has a structure in which a heater film 2 is formed on a heat-resistant substrate 1, and electrodes 41 and 42 and a gas sensitive film 51 are formed thereon with an insulating film 3 interposed therebetween. If the heat-resistant substrate 1 is conductive, it is necessary to form an insulating film between it and the heater film.
なお、（イ）は断面図、（ロ）は斜視図である。また、
６１及び６２はヒーター膜２への電力供給線、７１及び
７２はガス感応膜５１の信号取り出し線を表わしている
。第２図は電極よりもガス感応膜５１を先に形成した場
合の構造である。Note that (a) is a cross-sectional view, and (b) is a perspective view. Also,
Reference numerals 61 and 62 represent power supply lines to the heater membrane 2, and 71 and 72 represent signal extraction lines from the gas sensitive membrane 51. FIG. 2 shows a structure in which the gas sensitive film 51 is formed before the electrodes.
一方、第３図は他のガスセンサの代表的なものの概略を
示しており、ここでは一対の電極を兼ねたヒーターコイ
ル４３．４４間に２〜３ｍ角の金属酸化物半導体の焼結
体（ガス感応物質５２）を保持させている。なお、この
タイプのガスセンサは、一対の電極の一方（例えば電極
４３）と他方（例えば電極４４）とからガス感応物質５
２の信号取り出し線が引出せるように工夫されており、
また、ヒーターコイル４３．４４はガス感応物質５２の
層内に埋め込まれた状態で存在せしめられている。図中
、１２はベース、８は電極ピンである。On the other hand, FIG. 3 shows an outline of a typical gas sensor. Here, a 2 to 3 m square metal oxide semiconductor sintered body (gas A sensitive substance 52) is retained. Note that this type of gas sensor has a gas-sensitive substance 5 from one of the pair of electrodes (for example, electrode 43) and the other (for example, electrode 44).
It is devised so that the signal extraction line of 2 can be drawn out,
Furthermore, heater coils 43 and 44 are embedded within the layer of gas-sensitive material 52. In the figure, 12 is a base, and 8 is an electrode pin.
しかし、第３図に示したタイプのものでは消費電力が大
きく、また、熱容量が大きいため応答性に問題がある、
これに対して、第１，２図に示したタイプのガスセンサ
は、ガス感応物質が薄膜であるため消費電力、応答性と
も良好であるが、経時変化が大きく実用に至っていない
。However, the type shown in Figure 3 consumes a lot of power and has a large heat capacity, so there are problems with responsiveness.
On the other hand, the gas sensors of the type shown in FIGS. 1 and 2 have good power consumption and responsiveness because the gas-sensitive material is a thin film, but they change over time and are not put to practical use.
この原因は金属酸化物半導体の結晶粒の増大化にある。The cause of this is the increase in crystal grains of the metal oxide semiconductor.
ガスセンサは通常３００〜４５０℃の高温で使用される
ため、長期間使用すると、金属酸化物半導体の結晶粒径
が増大し、吸着面積の減少或いは化学的活性度の減少を
引き起こし、ガス感度の低下を招くという欠点を有する
。Gas sensors are usually used at high temperatures of 300 to 450°C, so when used for a long period of time, the crystal grain size of the metal oxide semiconductor increases, causing a decrease in adsorption area or chemical activity, resulting in a decrease in gas sensitivity. It has the disadvantage of causing
本発明の目的は、経時変化に対する特性が優れた薄膜ガ
スセンサの促供にある。An object of the present invention is to provide a thin film gas sensor with excellent characteristics against changes over time.
本発明の１つは、絶縁性基板上に形成された金属酸化物
半導体薄膜の抵抗値変化を利用してガス検出を行なう金
属酸化物半導体薄膜ガスセンサにおいて、金属酸化物半
導体薄膜上に絶縁性薄膜が被覆されていることを特徴と
するガスセンサに関する。One aspect of the present invention is a metal oxide semiconductor thin film gas sensor that detects gas by utilizing a change in the resistance value of a metal oxide semiconductor thin film formed on an insulating substrate. The present invention relates to a gas sensor characterized in that it is coated with.
本発明の他の１つは、絶縁性基板上に形成された金属酸
化物半導体薄膜の抵抗値変化を利用してガス検出を行な
う金属酸化物半導体薄膜ガスセンサにおいて、金属酸化
物半導体薄膜が絶縁性薄膜との交互積層構造体となって
いることを特徴とするガスセンサに関する。Another aspect of the present invention is a metal oxide semiconductor thin film gas sensor that detects gas by utilizing a change in resistance of a metal oxide semiconductor thin film formed on an insulating substrate, in which the metal oxide semiconductor thin film has an insulating property. The present invention relates to a gas sensor characterized by having a structure in which thin films are alternately laminated.
いいかえれば、第２の本発明は、第１図、第２図に示す
ような薄膜ガスセンサにおいて、薄膜の構成を金属酸化
物半導体薄膜と絶縁性薄膜とを交互に堆積した積層構造
としたことを特徴とするものである。In other words, the second invention provides a thin film gas sensor as shown in FIGS. 1 and 2, in which the thin film has a laminated structure in which metal oxide semiconductor thin films and insulating thin films are alternately deposited. This is a characteristic feature.
ちなみに本発明者等はいろいろな角度から検討を行なっ
た結果、薄膜ガスセンサの経時変化が大きい原因の一つ
に、金属酸化物半導体の結晶粒の増大化があることを確
かめた。ガスセンサは通常３００〜４５０℃の高温で使
用されるため、長期間使用すると金属酸化物半導体の結
晶化が進み、結晶粒径が増大し、吸着面積の減少或いは
化学的活性度の減少等を引き起こし、ガス感度の低下を
招く。又、間欠的に加熱して使用する場合、室温との間
で温度サイクルを受けるため、金属酸化物半導体薄膜と
基板或いは他の膜との熱膨張係数の違いにより、引張り
或いは圧縮応力を受ける。これらの歪は転移の滑りやヒ
ロックの成長により緩和される。このような変化を生ず
るとガス感度或いは抵抗値の変化となって表れる。この
ような現象を防ぐ一つの方法は、金属酸化物半導体薄膜
を予めできるだけ高温でアニールしておくことだが、薄
膜の場合にはアニール温度の上昇に伴い膜強度が減少し
基板から剥離しやすくなるため、７００’Ｃ程度が限界
である。焼結型ガスセンサの場合には、バインダーとし
て５ｉｎ２やＡＱ２０３等を添加しているため、１００
０℃以上の高温で焼結することができる。Incidentally, as a result of studies conducted from various angles, the inventors of the present invention have confirmed that one of the causes of large temporal changes in thin film gas sensors is an increase in the size of crystal grains in metal oxide semiconductors. Gas sensors are usually used at high temperatures of 300 to 450°C, so if used for a long period of time, the metal oxide semiconductor will crystallize, increasing the crystal grain size, causing a decrease in adsorption area or chemical activity. , leading to a decrease in gas sensitivity. Furthermore, when used with intermittent heating, the metal oxide semiconductor thin film is subjected to temperature cycles with respect to room temperature, and is subjected to tensile or compressive stress due to the difference in thermal expansion coefficient between the metal oxide semiconductor thin film and the substrate or other film. These strains are relaxed by dislocation sliding and hillock growth. When such a change occurs, it appears as a change in gas sensitivity or resistance value. One way to prevent this phenomenon is to anneal the metal oxide semiconductor thin film at as high a temperature as possible beforehand, but in the case of thin films, as the annealing temperature increases, the film strength decreases and it becomes easier to peel off from the substrate. Therefore, the limit is about 700'C. In the case of sintered gas sensors, 5in2, AQ203, etc. are added as binders, so 100%
It can be sintered at a high temperature of 0°C or higher.
又それらの添加方法がその製法上比較的容易である。し
かし、薄膜の場合、これらを膜中に均一に添加すること
は非常に困難である。Moreover, the method of adding them is relatively easy in terms of manufacturing method. However, in the case of a thin film, it is very difficult to uniformly add these into the film.
そこで我々は、金属酸化物半導体薄膜上に、比較的高融
点の絶縁性薄膜を堆積し、それらの複合構造としたあと
に高温でアニールを行って得られた第１の本発明にかか
る薄膜ガスセンサの経時特性について検討した。その結
果、経時変化に対して極めてすぐれた特性をもつことが
確認された。Therefore, we deposited an insulating thin film with a relatively high melting point on a metal oxide semiconductor thin film, formed a composite structure of these, and then annealed it at a high temperature to create a thin film gas sensor according to the first invention. We investigated the characteristics over time. As a result, it was confirmed that the material has extremely excellent characteristics against changes over time.
本発明に使用する金属酸化物半導体薄膜としては、とく
に制限はないが例えば、スズ、チタン、インジウム、ニ
ッケル、タングステン、カドミウム、鉄、亜鉛等の酸化
物が良く、絶縁性薄膜としてはとくに制限はないが例え
ば、ＳｉＯ□、Ａｆ１２０３、Ｔａ２０５． ＭｇＯ等
が良い。各層の膜厚は金属酸化物半導体薄膜が５００〜
５０００人、絶縁性薄膜は５０〜５００人程度が適当で
ある。絶縁性薄膜の膜厚が５０Å以下では経時劣化に対
する効果が小さく、５００Å以上になると被検ガスが金
属酸化物半導体薄膜に到達することが阻止されるためガ
ス感度が全く生じない。There are no particular restrictions on the metal oxide semiconductor thin film used in the present invention, but oxides of tin, titanium, indium, nickel, tungsten, cadmium, iron, zinc, etc. are suitable, but there are no particular restrictions on the insulating thin film. For example, SiO□, Af1203, Ta205. MgO etc. are good. The film thickness of each layer is 500 mm for metal oxide semiconductor thin films.
Appropriate number of people is 5,000 people, and about 50 to 500 people for insulating thin film. When the thickness of the insulating thin film is less than 50 Å, the effect on aging deterioration is small, and when it is more than 500 Å, gas sensitivity is not caused at all because the test gas is prevented from reaching the metal oxide semiconductor thin film.
また、本発明者等は、金属酸化物半導体薄膜と比較的高
融点の絶縁性薄膜とを交互に堆積し、それらの積層構造
としたあとに高温でアニールを行って得られた第２の本
発明にかかる薄膜ガスセンサの経時特性について検討し
た。積層の例を第６図に示す。１１は金属酸化物半導体
薄膜、１３は絶縁性薄膜である。In addition, the present inventors deposited a metal oxide semiconductor thin film and an insulating thin film with a relatively high melting point alternately, formed a stacked structure of these, and then annealed the film at a high temperature. The aging characteristics of the thin film gas sensor according to the invention were investigated. An example of lamination is shown in FIG. 11 is a metal oxide semiconductor thin film, and 13 is an insulating thin film.
各層の膜厚は金属酸化物半導体薄膜が５００〜５０００
人、絶縁性薄膜は、１００〜１０００人程度が適当てあ
り、金属酸化物半導体薄膜の暦数は２〜５層、絶縁性薄
膜の暦数は１〜４層程度が適当である。The thickness of each layer is 500 to 5000 for metal oxide semiconductor thin films.
The appropriate number of people for the insulating thin film is about 100 to 1000 people, the appropriate number of layers for the metal oxide semiconductor thin film is 2 to 5 layers, and the appropriate number of layers for the insulating thin film is about 1 to 4 layers.
この第２の本発明の場合も経時変化に対して極めてすぐ
れた特性をもつことが確認された。It was confirmed that this second invention also has extremely excellent characteristics against changes over time.
金属酸化物半導体薄膜の成膜方法としては、真空蒸着法
でもスパッタリング法でも、あるいは他の方法で形成し
ても良いが、本発明者の一人である太田が発明したグ薄
膜蒸着装置ｊ （特開昭５９−８９７６３号公報）を用
いることが好ましい。The metal oxide semiconductor thin film may be formed by vacuum evaporation, sputtering, or other methods. It is preferable to use JP-A-59-89763).
本発明の思想は第１図に表されたタイプのものに限られ
るわけではなく、本発明者等が既に提案しであるマイク
ロヒーター構造を有するガスセンサ（特開平１−１６７
６４５号）のカス検知膜にも適用することができる。The idea of the present invention is not limited to the type shown in FIG.
It can also be applied to the scum detection film of No. 645).
実施例１（請求項１，３に対応）
蒸発材料としては金属スズを用い、予め１Ｏ−４Ｐａ台
に真空引きした真空槽内に酸素ガスを導入し、圧力を０
．２Ｐａとした状態でフィラメントに７０Ａ程度の電流
を印加し熱電子を発生させ、グリッドに１００ｖ程度の
電圧を印加しプラズマを発生させ、成膜速度を２０人／
ｓｅｃ程度にて３０００人の酸化スズ薄膜を形成した。Example 1 (corresponding to claims 1 and 3) Metal tin was used as the evaporation material, oxygen gas was introduced into a vacuum chamber that had been evacuated to 10-4 Pa level, and the pressure was reduced to 0.
．． At a pressure of 2 Pa, a current of about 70 A is applied to the filament to generate thermoelectrons, a voltage of about 100 V is applied to the grid to generate plasma, and the deposition rate is increased to 20 people/day.
A tin oxide thin film of 3,000 people was formed in about 2 seconds.
５ｉｎ２膜の形成方法について、様々な方法が考えられ
るが、今回は、真空槽内に酸素ガスを導入し、圧力を０
．ＩＰａとした状態で蒸発材料であるＳｉＯを抵抗加熱
法により蒸発させて１００人の５ｉｎ２膜を形成した。Various methods can be considered for forming the 5in2 film, but this time we will introduce oxygen gas into the vacuum chamber and reduce the pressure to 0.
．． SiO, which is an evaporation material, was evaporated using a resistance heating method in a state of IPa to form a 5in2 film of 100 people.
その後、酸素雰囲気中で１０００℃、３時間のアニルを
施した。その結果、１０００°Ｃの高温にもかかわらず
膜強度は非常に強固であり、基板からの剥がれも全くみ
られず、ガス感度についても十分な値を有していた。こ
の構成のセンサを４５０℃で３００日間連続使用したが
、ガス感度の低下は全くみられなかった。これは高温の
アニールにより酸化スズは微結晶化し、その空隙にＳｉ
Ｏ□が分散され（第５図）、それがバインダーの役目を
果たし膜を強固なものとすると共に酸化スズの結晶粒径
の増大を抑制するためと考えられる。Thereafter, annealing was performed at 1000° C. for 3 hours in an oxygen atmosphere. As a result, despite the high temperature of 1000°C, the film strength was very strong, no peeling from the substrate was observed, and the gas sensitivity was also sufficient. A sensor with this configuration was used continuously at 450° C. for 300 days, but no decrease in gas sensitivity was observed. This is because the tin oxide becomes microcrystallized due to high-temperature annealing, and the voids are filled with Si.
It is thought that this is because O□ is dispersed (Fig. 5), which acts as a binder to strengthen the film and suppress the increase in the crystal grain size of tin oxide.
実施例２（請求項２，３に対応）
蒸発材料としては金属スズを用い、真空槽内に酸素ガス
を導入し、圧力を０．２Ｐａとした状態でフィラメント
に７０Ａ程度の電流を印加し熱電子を発生させ、グリッ
ドに１００Ｖ程度の電圧を印加しプラズマを発生させ、
成膜速度を２０人／ｓｅｅ程度にて酸化スズ薄膜を形成
した。ＳｉＯ２膜の形成方法について、様々な方法が考
えられるが、今回は、真空槽内に酸素ガスを導入し、圧
力を０、ＩＰａとした状態で蒸発材料であるＳｉＯを抵
抗加熱法により蒸発させて形成した。以上のような方法
により、金属酸化物半導体薄膜と絶縁性薄膜とを交互に
積層した。積層数は金属酸化物半導体薄膜（１０００人
）３層及び絶縁性薄膜（］０００人２層である。その後
、酸素雰囲気中で１０００℃、３時間のアニールを施し
た。その結果、１０００℃の高温にもかかわらず膜強度
は非常に強固であり、基板からの剥がれも全くみられず
、ガス感度についても十分な値を有していた。この構成
のセンサを４５０°Ｃで３００日間連続使用したが、ガ
ス感度の低下は全くみられなかった。これは高温のアニ
ールにより酸化スズは微結晶化し、その空隙にＳｉＯ□
が分散され（第７図）、それがバインダーの役目を果た
し膜を強固なものとすると共に酸化スズの結晶粒径の増
大を抑制するためと考えられる。Example 2 (corresponding to claims 2 and 3) Metal tin was used as the evaporation material, oxygen gas was introduced into a vacuum chamber, and a current of about 70 A was applied to the filament at a pressure of 0.2 Pa to heat it. Generate electrons and apply a voltage of about 100V to the grid to generate plasma,
A tin oxide thin film was formed at a film formation rate of about 20 people/see. Various methods can be considered to form the SiO2 film, but in this case, oxygen gas is introduced into the vacuum chamber, and SiO, which is the evaporation material, is evaporated using a resistance heating method at a pressure of 0 and IPa. Formed. By the method described above, metal oxide semiconductor thin films and insulating thin films were alternately laminated. The number of laminated layers is 3 layers of metal oxide semiconductor thin film (1000 layers) and 2 layers of insulating thin film (2000 layers).After that, annealing was performed at 1000°C for 3 hours in an oxygen atmosphere.As a result, the 1000°C Despite the high temperature, the film was extremely strong, showed no peeling from the substrate, and had sufficient gas sensitivity.A sensor with this configuration was used continuously at 450°C for 300 days. However, no decrease in gas sensitivity was observed at all.This is because tin oxide becomes microcrystallized due to high-temperature annealing, and SiO□
is dispersed (Fig. 7), which acts as a binder to strengthen the film and suppress the increase in the crystal grain size of tin oxide.
本発明の構成により、経時変化に対する特性が極めてす
ぐれた薄膜ガスセンサが得られた。With the configuration of the present invention, a thin film gas sensor with extremely excellent characteristics against changes over time was obtained.
第１図は、薄膜状ガス感応膜をもつガスセンサであり、
（イ）は断面図、４口）は斜視図である。第２図は、第
１図の変形型の断面図である。第３図は、従来のガスセ
ンサを示し、第４図は、本発明実施例１の薄膜ガスセン
サの具体的構成例を示す断面図であり、第５図はその熱
処理後の金属酸化物半導体薄膜とその上に被覆されたＳ
ｉ Ｏ２／ｆの推定構造を示し、第６図は、本発明実
施例２の薄膜ガスセンサの具体的構成例を示す断面図で
あり、第７図は、その熱処理後の金属酸化物半導体薄膜
の推定構造を示す。
■・・・耐熱性基板 ２ ・ヒーター膜３・・・絶縁
膜 ８・・・電極ピン１１・・金属酸化物半導
体薄膜
１２・・べ〜ス １３・・・絶縁性薄膜２１・
・酸化スズ粒子
２２・・・ＳｉＯ□粒子 ４１．４２・・電極４３
．４４・・電極兼ヒーターコイルFIG. 1 shows a gas sensor with a thin gas-sensitive film,
(a) is a sectional view, and (4) is a perspective view. FIG. 2 is a sectional view of a modified version of FIG. 1. FIG. 3 shows a conventional gas sensor, FIG. 4 is a cross-sectional view showing a specific configuration example of a thin film gas sensor according to Embodiment 1 of the present invention, and FIG. 5 shows a metal oxide semiconductor thin film after heat treatment. S coated on it
FIG. 6 is a sectional view showing a specific configuration example of the thin film gas sensor of Example 2 of the present invention, and FIG. 7 is a cross-sectional view of the metal oxide semiconductor thin film after heat treatment. The estimated structure is shown. ■ Heat-resistant substrate 2 Heater film 3 Insulating film 8 Electrode pin 11 Metal oxide semiconductor thin film 12 Base 13 Insulating thin film 21
・Stin oxide particles 22...SiO□ particles 41.42...Electrode 43
．． 44...Electrode/heater coil
Claims (1)
抵抗値変化を利用してガス検出を行なう金属酸化物半導
体薄膜ガスセンサにおいて、金属酸化物半導体薄膜上に
絶縁性薄膜が被覆されていることを特徴とするガスセン
サ。 ２、絶縁性基板上に形成された金属酸化物半導体薄膜の
抵抗値変化を利用してガス検出を行なう金属酸化物半導
体薄膜ガスセンサにおいて、金属酸化物半導体薄膜が絶
縁性薄膜との交互積層構造体となっていることを特徴と
するガスセンサ。 ３、前記金属酸化物半導体薄膜と絶縁性薄膜との複合体
または交互積層構造体が熱処理されたものであることを
特徴とする請求項１または２記載のガスセンサ。[Claims] 1. In a metal oxide semiconductor thin film gas sensor that detects gas using a change in resistance of a metal oxide semiconductor thin film formed on an insulating substrate, an insulating film is formed on the metal oxide semiconductor thin film. A gas sensor characterized by being coated with a thin film. 2. In a metal oxide semiconductor thin film gas sensor that detects gas by utilizing a change in the resistance value of a metal oxide semiconductor thin film formed on an insulating substrate, a metal oxide semiconductor thin film is an alternately laminated structure with an insulating thin film. A gas sensor characterized by: 3. The gas sensor according to claim 1 or 2, wherein the composite or alternately laminated structure of the metal oxide semiconductor thin film and the insulating thin film is heat-treated.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/668,617 US5250170A (en) | 1990-03-15 | 1991-03-13 | Gas sensor having metal-oxide semiconductor layer |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6525890 | 1990-03-15 | ||
| JP2-65258 | 1990-03-15 | ||
| JP2-150408 | 1990-06-08 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH04127047A true JPH04127047A (en) | 1992-04-28 |
Family
ID=13281709
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP23969190A Pending JPH04127047A (en) | 1990-03-15 | 1990-09-10 | Gas sensor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH04127047A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007147655A (en) * | 2007-03-09 | 2007-06-14 | Ngk Spark Plug Co Ltd | Gas sensor element |
| US7276745B2 (en) | 2005-02-22 | 2007-10-02 | Ngk Spark Plug Co., Ltd. | Gas sensor |
| DE102013008937A1 (en) | 2012-05-25 | 2013-11-28 | Suzuki Motor Corporation | Pillar trim structure |
-
1990
- 1990-09-10 JP JP23969190A patent/JPH04127047A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7276745B2 (en) | 2005-02-22 | 2007-10-02 | Ngk Spark Plug Co., Ltd. | Gas sensor |
| JP2007147655A (en) * | 2007-03-09 | 2007-06-14 | Ngk Spark Plug Co Ltd | Gas sensor element |
| JP4603001B2 (en) * | 2007-03-09 | 2010-12-22 | 日本特殊陶業株式会社 | Gas sensor element |
| DE102013008937A1 (en) | 2012-05-25 | 2013-11-28 | Suzuki Motor Corporation | Pillar trim structure |
| US9033388B2 (en) | 2012-05-25 | 2015-05-19 | Suzuki Motor Corporation | Pillar trim structure |
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