JPH085591A - Gas sensor and its manufacture - Google Patents
Gas sensor and its manufactureInfo
- Publication number
- JPH085591A JPH085591A JP13877594A JP13877594A JPH085591A JP H085591 A JPH085591 A JP H085591A JP 13877594 A JP13877594 A JP 13877594A JP 13877594 A JP13877594 A JP 13877594A JP H085591 A JPH085591 A JP H085591A
- Authority
- JP
- Japan
- Prior art keywords
- thin film
- gas
- gas sensor
- zno
- solution
- 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
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、ＺｎＯ薄膜を用いたガ
スセンサ及びその製造方法に関するもので、とりわけゾ
ルゲル法により形成した均一で緻密なＺｎＯ薄膜を有す
る水素ガスに対する感度が優れたガスセンサ及びその製
造方法に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas sensor using a ZnO thin film and a method for manufacturing the same, and more particularly to a gas sensor having a uniform and dense ZnO thin film formed by a sol-gel method and having excellent sensitivity to hydrogen gas, and manufacturing thereof. It is about the method.
【０００２】[0002]
【従来の技術】可燃性ガスとして知られる水素ガス（Ｈ
2 ）は、空気中に４〜８０％含まれると、引火により爆
発を引き起こす危険性の高いガスであることから、防災
や保安用は勿論、更には、昨今、環境計測、プロセス制
御、省エネルギー、家電機器の知能化等の諸分野におい
ても、水素ガス（Ｈ2 ）に対する感度の優れた検知素子
が望まれるようになっている。2. Description of the Related Art Hydrogen gas (H
2 ) is a gas with a high risk of causing an explosion due to ignition when it is contained in the air in an amount of 4 to 80%, so it is of course not only for disaster prevention and safety, but also recently, environmental measurement, process control, energy saving, In various fields such as intelligentization of home electric appliances, detection elements having excellent sensitivity to hydrogen gas (H 2 ) have been demanded.
【０００３】従来より、一般に希薄可燃性ガスを比較的
選択性よく検知できるガスセンサとして半導体式ガスセ
ンサが知られているが、この半導体式ガスセンサは、酸
化物半導体表面に被検ガスが接触すると酸化物半導体表
面の比抵抗が変化する事を利用して、被検ガスの種類と
濃度を検知するものである。Conventionally, a semiconductor type gas sensor has been generally known as a gas sensor capable of detecting a dilute combustible gas with relatively high selectivity. However, in this semiconductor type gas sensor, when a test gas comes into contact with an oxide semiconductor surface, the oxide is detected. The type and concentration of the test gas are detected by utilizing the fact that the specific resistance of the semiconductor surface changes.
【０００４】前記半導体式ガスセンサは、例えば、酸化
錫（ＳｎＯ2 ）、酸化亜鉛（ＺｎＯ）等から成るガス感
応体上に、酸化アルミニウム（Ａｌ2 Ｏ3 ）、酸化珪素
（ＳｉＯ2 ）等の担体とパラジウム（Ｐｄ）、白金（Ｐ
ｔ）等の触媒金属を含む触媒層を設けた構造から成るも
のが知られており、前記ガス感応体の形成方法として
は、例えばガス感応体をＺｎＯ薄膜で形成する場合に
は、一般にスパッタリング法等の気相合成法が採用され
ている。In the semiconductor gas sensor, for example, a carrier such as aluminum oxide (Al 2 O 3 ) or silicon oxide (SiO 2 ) is provided on a gas sensor made of tin oxide (SnO 2 ) or zinc oxide (ZnO). And palladium (Pd), platinum (Pd
A structure having a catalyst layer containing a catalytic metal such as t) is known. As a method for forming the gas sensitive body, for example, when the gas sensitive body is formed of a ZnO thin film, a sputtering method is generally used. Vapor phase synthesis methods such as
【０００５】即ち、前記気相合成法では、ＺｎＯ焼結体
から成る蒸発源より蒸発物質を蒸発させ、３００℃以上
に加熱した電気絶縁性基板表面にＺｎＯ薄膜を成膜する
と同時に、基板表面に酸素を供給することによりＺｎＯ
薄膜が作製されている（特開平３−１２３８４５号公
報、特開平４−１２７０４７号公報参照）。That is, in the vapor phase synthesis method, an evaporation material is evaporated from a ZnO sintered body to form a ZnO thin film on the surface of an electrically insulating substrate heated to 300 ° C. or higher, and at the same time, the ZnO thin film is formed on the surface of the substrate. ZnO by supplying oxygen
A thin film has been produced (see Japanese Patent Application Laid-Open Nos. 3-123845 and 4-127047).
【０００６】[0006]
【発明が解決しようとする課題】しかしながら、前記ス
パッタリング法によれば、得られるＺｎＯ薄膜は疎にし
て嵩だかの柱状構造を有する大きな粒径の膜となり、密
に重畳した粒径の小さな均一かつ緻密な薄膜を得ること
は困難であった。However, according to the above-mentioned sputtering method, the obtained ZnO thin film becomes a film having a large grain size having a sparse and bulky columnar structure, and the dense and uniform particles having a small grain size are formed. It was difficult to obtain a dense thin film.
【０００７】そのために、この薄膜の表面に検知電極を
接続してガスセンサ素子を形成した場合、該薄膜の表面
積が小さいことから、水素ガスと他のガスが示すそれぞ
れの抵抗変化の差が小さく、充分な水素ガス感応特性を
発揮することができない他、検知電極の接合が均一とな
らず、再現性の良いセンサ特性を有するガスセンサが得
られないという課題があった。Therefore, when a gas sensor element is formed by connecting a detection electrode to the surface of this thin film, the surface area of the thin film is small, so that the difference in resistance change between hydrogen gas and other gases is small, There is a problem that a sufficient hydrogen gas responsive property cannot be exhibited, the bonding of the detection electrodes is not uniform, and a gas sensor having a reproducible sensor property cannot be obtained.
【０００８】[0008]
【発明の目的】本発明は前記課題に鑑みなされたもの
で、その目的は、水素ガスに対する感度が優れ、均一で
密に重畳した粒径の小さいＺｎＯ薄膜から成るガス感応
体を備えた再現性の良いセンサ特性を有するガスセンサ
と、水素ガス感応特性に優れたＺｎＯ薄膜から成るガス
感応体を容易に作製できる新規な製造方法を提供するこ
とにある。SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object thereof is to provide reproducibility with a gas sensitizer comprising a ZnO thin film which is excellent in sensitivity to hydrogen gas and which has a uniform and densely superimposed small particle size. (EN) A novel manufacturing method capable of easily producing a gas sensor having excellent sensor characteristics and a gas sensitive body composed of a ZnO thin film excellent in hydrogen gas sensitive characteristics.
【０００９】[0009]
【課題を解決するための手段】本発明者等は、前記課題
に対して検討を重ねた結果、薄膜成分を分散媒中に分散
させてゾル化した後、加熱してゲル化させるゾルゲル法
の手法に基づき、亜鉛アルコキシドまたは亜鉛アセチル
アセトナートを有機溶媒に溶解してなる溶液を部分加水
分解する際に、その溶液中にＲｎＮ（ＣＨ2 ＣＨ2 Ｏ
Ｈ）3-n （式中、Ｒは、Ｈ、ＣＨ3 、Ｃ2 Ｈ5 のいずれ
か、ｎは０〜２のいずれかの整数）で表されるエタノー
ルアミンを添加することにより大気中の水分に対する安
定性を高めることができ、該溶液を所定の基板表面に塗
布し、酸化性雰囲気中で５００℃以上の温度で熱処理す
ることにより、前述のような柱状構造や大きな粒径を有
しない、均一で密に重畳した粒径の小さなＺｎＯ薄膜が
得られ、この薄膜表面に検知電極を接続することにより
優れたガスセンサ素子が得られることを見いだし、本発
明に至ったものである。Means for Solving the Problems As a result of extensive studies on the above problems, the present inventors have found that a sol-gel method in which a thin film component is dispersed in a dispersion medium to form a sol and then heated to form a gel. According to the method, when a solution obtained by dissolving zinc alkoxide or zinc acetylacetonate in an organic solvent is partially hydrolyzed, RnN (CH 2 CH 2 O
H) 3-n (wherein R is H, CH 3 , or C 2 H 5 , and n is an integer of 0 to 2), and the ethanolamine represented by the formula The stability against moisture can be enhanced, and the solution is applied to a predetermined substrate surface and heat-treated at a temperature of 500 ° C. or higher in an oxidizing atmosphere, so that the columnar structure and the large particle size as described above are not generated. It was found that a ZnO thin film having a uniform and dense superposition and a small grain size can be obtained, and an excellent gas sensor element can be obtained by connecting a detection electrode to the surface of the thin film, and the present invention has been completed.
【００１０】即ち、本発明のガスセンサ及びその製造方
法は、電気絶縁性の基板表面にゾルゲル法により形成し
たＺｎＯ薄膜から成るガス感応体と、そのガス感応体に
接続した一対の検知電極から成ることを特徴とするもの
であり、その製造方法は、ＲｎＮ（ＣＨ2 ＣＨ2 ＯＨ）
3-n （式中、ＲはＨ、ＣＨ3 、Ｃ2 Ｈ5 のいずれか、ｎ
は０〜２のいずれかの整数）で表されるエタノールアミ
ンを含有する有機溶媒に、被着形成する薄膜の亜鉛成分
を含有したアルコキシドあるいは有機酸塩を溶解し、加
水分解した溶液を前記電気絶縁性の基板表面に塗布した
後、酸化性雰囲気中、５００℃以上の温度で熱分解して
ＺｎＯ薄膜を被着形成することを特徴とするものであ
る。That is, the gas sensor and the method for manufacturing the same according to the present invention comprise a gas sensitive body composed of a ZnO thin film formed on the surface of an electrically insulating substrate by a sol-gel method, and a pair of detection electrodes connected to the gas sensitive body. And its manufacturing method is RnN (CH 2 CH 2 OH)
3-n (wherein R is H, CH 3 , or C 2 H 5 , n
Is an integer of 0 to 2), an alkoxide or an organic acid salt containing a zinc component of a thin film to be deposited is dissolved in an organic solvent containing ethanolamine, and the hydrolyzed solution is converted into the electrolyzed solution. After being applied to the surface of an insulating substrate, the ZnO thin film is deposited by thermal decomposition in an oxidizing atmosphere at a temperature of 500 ° C. or higher.
【００１１】[0011]
【作用】本発明のガスセンサ及びその製造方法によれ
ば、ゾルゲル法に基づき薄膜を作製するに際して、亜鉛
原料として亜鉛アルコキシドまたは亜鉛アセチルアセト
ナートを用い、これを溶解した塗布用溶液に安定化剤と
して前述のエタノールアミンを加えたことから、該エタ
ノールアミンは亜鉛イオンとの結合力が強く、かつ高沸
点であるためにＺｎＯの結晶化の速度を制御することが
でき、得られるＺｎＯ薄膜の均質性、及び緻密性を大き
く向上することができる。According to the gas sensor and the method for producing the same of the present invention, when a thin film is formed based on the sol-gel method, zinc alkoxide or zinc acetylacetonate is used as a zinc raw material, and this is dissolved as a stabilizer in a coating solution. Since the above-mentioned ethanolamine is added, since the ethanolamine has a strong binding force with zinc ions and has a high boiling point, the crystallization rate of ZnO can be controlled, and the homogeneity of the obtained ZnO thin film can be controlled. , And the denseness can be greatly improved.
【００１２】実際にエタノールアミンを含まない溶液を
用いてＺｎＯ薄膜を作製すると、薄膜中に針状の結晶が
無数に発生して不均一な膜となってしまう。When a ZnO thin film is actually produced using a solution containing no ethanolamine, numerous needle-like crystals are generated in the thin film, resulting in a non-uniform film.
【００１３】また、ゾルゲル法では、一度に膜厚の大き
な成膜が困難であり、１０ｎｍ厚程度の成膜と焼成を反
復するため、結晶化が成膜毎の個々に分けられることか
ら、焼成温度を制御することにより結晶の巨大化が避け
られ、微細な結晶が密に得られる。Further, in the sol-gel method, it is difficult to form a film having a large film thickness at one time, and since film formation with a thickness of about 10 nm and baking are repeated, crystallization is divided into individual films. By controlling the temperature, enlargement of crystals is avoided, and fine crystals can be obtained densely.
【００１４】また、本発明の製造方法によれば、ＺｎＯ
薄膜の厚さは、前記塗布用溶液の濃度や、浸漬して塗布
する際の基板の引き上げ速度、塗布回数により容易に制
御することができる。According to the manufacturing method of the present invention, ZnO
The thickness of the thin film can be easily controlled by the concentration of the coating solution, the withdrawing speed of the substrate during dipping and coating, and the number of coatings.
【００１５】しかも、膜厚が３０ｎｍ程度と薄い場合に
おいても、最終的に得られる膜がポーラスな構造や柱状
構造を呈さず、しかもクラック等がない緻密な膜が得ら
れることから、例えばガスセンサ素子において膜表面に
電極を形成した場合においても、電流のリークのない再
現性の良いセンサ特性を有する優れたガスセンサ素子を
作製することができる。Moreover, even when the film thickness is as thin as about 30 nm, the film finally obtained does not have a porous structure or a columnar structure, and a dense film without cracks can be obtained. Even when the electrode is formed on the surface of the film, it is possible to produce an excellent gas sensor element having a sensor characteristic with good reproducibility without current leakage.
【００１６】[0016]
【実施例】以下、本発明を図面に基づき詳細に説明す
る。図１は、本発明のガスセンサのガス感応体を含む断
面の組織を示す電子顕微鏡写真であり、図２はガスセン
サのガス感応体を成すＺｎＯ薄膜の表面の結晶構造を示
す電子顕微鏡写真である。The present invention will be described in detail below with reference to the drawings. FIG. 1 is an electron micrograph showing a structure of a cross section including a gas sensor of the gas sensor of the present invention, and FIG. 2 is an electron micrograph showing a crystal structure of a surface of a ZnO thin film forming the gas sensor of the gas sensor.
【００１７】図１及び図２において、１は電気絶縁性基
板２の表面にゾルゲル法により形成したガス感応体を成
すＺｎＯ薄膜である。In FIGS. 1 and 2, reference numeral 1 is a ZnO thin film forming a gas sensitive body formed on the surface of the electrically insulating substrate 2 by a sol-gel method.
【００１８】前記ＺｎＯ薄膜１は、膜厚が１０００〜１
５００Åであるため、その結晶は、粒径が０．１μm 以
下の微粒子の集合体となっている。The ZnO thin film 1 has a thickness of 1000 to 1
Since it is 500 Å, the crystal is an aggregate of fine particles having a particle size of 0.1 μm or less.
【００１９】また、図３は本発明のガスセンサの製造方
法の一実施例を説明する塗布用溶液を調製するための装
置の概略図であり、３は反応溶液、４は部分加水分解用
溶液、５は注射器、６は還流器である。FIG. 3 is a schematic view of an apparatus for preparing a coating solution for explaining an embodiment of the gas sensor manufacturing method of the present invention. 3 is a reaction solution, 4 is a partial hydrolysis solution, 5 is a syringe and 6 is a reflux device.
【００２０】本発明によれば、反応溶液３として、亜鉛
原料である亜鉛アルコキシドまたは亜鉛アセチルアセト
ナートをを有機溶媒に溶解したものを用意する。According to the present invention, the reaction solution 3 is prepared by dissolving zinc alkoxide or zinc acetylacetonate, which is a zinc raw material, in an organic solvent.
【００２１】この時に用いる有機溶媒としては、原料の
溶解性及び溶液の安定性の観点から第１アルコールが適
当であり、具体的には、エタノール、ｎ−プロパノー
ル、ｎ−ブタノール、ｎ−ペンタノール、ｎ−ヘキサノ
ール、イソアミルアルコール、２−メトキシエタノー
ル、２−エトキシエタノール等が利用できるが、原料と
して亜鉛アルコキシドを用いる場合は、上述のアルコー
ル溶媒にはほとんど溶解しないため、更にアセチルアセ
トン等を原料の２〜４倍モル量の割合で添加する必要が
ある。As the organic solvent used at this time, a primary alcohol is suitable from the viewpoint of the solubility of the raw materials and the stability of the solution, and specifically, ethanol, n-propanol, n-butanol, n-pentanol. , N-hexanol, isoamyl alcohol, 2-methoxyethanol, 2-ethoxyethanol and the like can be used, but when a zinc alkoxide is used as a raw material, it hardly dissolves in the alcohol solvent described above, and therefore acetylacetone or the like is used as a raw material. It is necessary to add it in a molar ratio of about 4 times.
【００２２】即ち、前記アセチルアセトン等の添加によ
り、恐らく、亜鉛アルコキシドの一部、または全部が、
溶液中で亜鉛アセチルアセトナートに変化し、溶解して
いるものと考えられる。That is, by the addition of the above-mentioned acetylacetone, etc., it is possible that some or all of the zinc alkoxide is
It is considered that it changed into zinc acetylacetonate in the solution and dissolved.
【００２３】次に、亜鉛原料に対して０．１〜２倍モル
の蒸留水を反応溶液３と同じ溶媒で希釈して調製した部
分加水分解用溶液４を注射器５に入れ、反応溶液３に徐
々に添加する。Next, the solution for partial hydrolysis 4 prepared by diluting 0.1 to 2 times the molar amount of distilled water with the same solvent as the reaction solution 3 with respect to the zinc raw material is put in the syringe 5 to make the reaction solution 3. Add slowly.
【００２４】尚、前記部分加水分解用溶液４を反応溶液
５に添加して加水分解させる際、系中にＲｎＮ（ＣＨ2
ＣＨ2 ＯＨ）3-n （式中、Ｒは、Ｈ、ＣＨ3 、Ｃ2 Ｈ5
のいずれか、ｎは０〜２のいずれかの整数）で表される
エタノールアミンが存在することが重要であり、このエ
タノールアミンの添加により、最終的に得られるＺｎＯ
薄膜の均質性及び緻密性が大きく向上する。When the solution 4 for partial hydrolysis is added to the reaction solution 5 for hydrolysis, RnN (CH 2
CH 2 OH) 3-n (wherein R is H, CH 3 , C 2 H 5
It is important that ethanolamine represented by any of the above, n is an integer of 0 to 2) is present, and ZnO finally obtained by the addition of this ethanolamine.
The homogeneity and denseness of the thin film are greatly improved.
【００２５】前記エタノールアミンは、反応溶液５また
は加水分解用溶液４のいずれにも添加することができ、
その量は亜鉛原料の０．５〜２倍モル量が適当である。The ethanolamine can be added to either the reaction solution 5 or the hydrolysis solution 4,
The amount is preferably 0.5 to 2 times the molar amount of the zinc raw material.
【００２６】前記加水分解は、基板に塗布する溶液中
に、金属−酸素−金属のメタロキサン結合を有する中間
体を形成させるために行うものであり、この中間体の存
在により、基板塗布後の熱処理過程でＺｎＯ薄膜の結晶
化が促進される。The above-mentioned hydrolysis is carried out to form an intermediate having a metal-oxygen-metal metalloxane bond in a solution to be coated on a substrate. Due to the presence of this intermediate, heat treatment after coating the substrate is carried out. In the process, crystallization of the ZnO thin film is promoted.
【００２７】このようにして部分加水分解用溶液４を滴
下した後、この溶液を１００℃で２〜１０時間加熱し、
室温まで冷却した後、反応溶液３と同じ溶媒を添加して
濃度調節を行い、塗布用溶液を作製する。After the partial hydrolysis solution 4 was added dropwise in this manner, the solution was heated at 100 ° C. for 2 to 10 hours,
After cooling to room temperature, the same solvent as the reaction solution 3 is added to adjust the concentration to prepare a coating solution.
【００２８】かくして得られた塗布用溶液を、所定の電
気絶縁性基板の表面に浸漬塗布法、ドクターブレード
法、スピンコート法等周知の塗布方法で塗布する。The coating solution thus obtained is coated on the surface of a predetermined electrically insulating substrate by a known coating method such as a dip coating method, a doctor blade method or a spin coating method.
【００２９】一例として浸漬塗布法について説明する
と、前記塗布用溶液中に所定の電気絶縁性基板を浸漬し
た後、０．５〜３ｍｍ／秒の一定速度で引き上げること
により、一定の厚さのＺｎＯゲル膜を作製することがで
き、また、厚さの厚い膜を作製する場合には、前記塗布
工程を繰り返し行えば良い。As an example, the dip coating method will be described. After dipping a predetermined electrically insulating substrate in the coating solution, it is pulled up at a constant rate of 0.5 to 3 mm / sec to obtain ZnO having a constant thickness. A gel film can be produced, and in the case of producing a thick film, the coating step may be repeated.
【００３０】次に、前記ＺｎＯゲル膜を表面に塗布した
電気絶縁性基板を酸化性雰囲気中、５００℃以上の温度
で熱分解させてＺｎＯ薄膜を得る。Next, the electrically insulating substrate coated with the ZnO gel film on its surface is thermally decomposed in an oxidizing atmosphere at a temperature of 500 ° C. or higher to obtain a ZnO thin film.
【００３１】尚、この際、熱処理条件として、熱処理温
度が５００℃よりも低いと薄膜の結晶性が低くなり、ま
た逆に１０００℃を越えると膜が電気絶縁性基板と反応
する恐れがあり、とりわけハイドロカーボンを完全に除
去するためには７００〜１０００℃の温度で０．５〜２
時間程度熱処理することが望ましい。At this time, as the heat treatment condition, if the heat treatment temperature is lower than 500 ° C., the crystallinity of the thin film becomes low, and conversely, if it exceeds 1000 ° C., the film may react with the electrically insulating substrate. In particular, in order to completely remove the hydrocarbon, 0.5 to 2 at a temperature of 700 to 1000 ° C.
It is desirable to heat-treat for about an hour.
【００３２】また、ＺｎＯ薄膜を構成する結晶粒子は、
水素ガスに対する感度及びガスセンサ特性の点から小さ
い結晶が密に形成されることが望ましく、その粒径は
０．２μm 以下、より望ましい範囲は０．１μm 以下と
なる。Further, the crystal grains constituting the ZnO thin film are
From the viewpoint of sensitivity to hydrogen gas and gas sensor characteristics, it is desirable that small crystals are densely formed, and the grain size is 0.2 μm or less, and a more desirable range is 0.1 μm or less.
【００３３】一方、前記ＺｎＯ薄膜は、その表面に検知
電極を形成してガスセンサ特性を感知することから、該
検知電極が断線しない程度の膜の緻密さと均一さが必要
である。On the other hand, since the ZnO thin film has a sensing electrode formed on its surface to sense the gas sensor characteristic, the ZnO thin film must be dense and uniform so that the sensing electrode is not broken.
【００３４】また、本発明のガスセンサは、前記ＺｎＯ
薄膜を作製する過程で、電気絶縁性基板２として、アル
ミナ、サファイア、石英またはガラス基板等の絶縁基板
を用い、前記塗布用溶液を基板表面に塗布した後、熱処
理を施すことにより、基板上にＺｎＯ薄膜から成るガス
感応体１を形成し、該ガス感応体１に一対の金（Ａｕ）
または白金（Ｐｔ）から成る検知電極（不図示）を接続
して得られる。Further, the gas sensor of the present invention is the ZnO
In the process of producing a thin film, an insulating substrate such as an alumina, sapphire, quartz or glass substrate is used as the electrically insulating substrate 2, and the coating solution is applied to the surface of the substrate and then subjected to heat treatment to form a thin film on the substrate. A gas sensor 1 composed of a ZnO thin film is formed, and a pair of gold (Au) is formed on the gas sensor 1.
Alternatively, it can be obtained by connecting a detection electrode (not shown) made of platinum (Pt).
【００３５】次に、本発明のガスセンサ及びその製造方
法を、以下の実施例１及び実施例２のようにして評価し
た。Next, the gas sensor of the present invention and the method for manufacturing the same were evaluated as in Examples 1 and 2 below.
【００３６】実施例１ 先ず、乾燥グローブボックス内で、ジエトキシ亜鉛３ｍ
ｍｏｌにｎ−ブタノール１００ｍｍｏｌ及びアセチルア
セトン９ｍｍｏｌを添加して反応溶液３を調製した。Example 1 First, 3 m of diethoxyzinc was placed in a dry glove box.
Reaction solution 3 was prepared by adding n-butanol 100 mmol and acetylacetone 9 mmol to mol.
【００３７】その後、この反応溶液３を図３に示す装置
の還流器６を取りつけたフラスコ内に収容し、該フラス
コ内を流れる乾燥気流中で攪拌を行った。Then, this reaction solution 3 was placed in a flask equipped with a reflux condenser 6 of the apparatus shown in FIG. 3, and stirred in a dry air stream flowing in the flask.
【００３８】次いで、予め用意したジエタノールアミン
３ｍｍｏｌ、蒸留水０．７５ｍｍｏｌ及びｎ−ブタノー
ル５０ｍｍｏｌから成る部分加水分解用溶液４を注射器
５でゆっくり滴下した後、１００℃の温度で１０時間加
熱した。Then, a partially hydrolyzed solution 4 consisting of 3 mmol of diethanolamine, 0.75 mmol of distilled water and 50 mmol of n-butanol prepared in advance was slowly added dropwise with a syringe 5 and then heated at a temperature of 100 ° C. for 10 hours.
【００３９】加熱終了後、室温まで冷却し、揮発した溶
媒に相当する量のｎ−ブタノールを添加して濃度調整を
行い、塗布用溶液を作製した。After completion of heating, the solution was cooled to room temperature and the concentration was adjusted by adding n-butanol in an amount corresponding to the volatilized solvent to prepare a coating solution.
【００４０】次に乾燥グローブボックス内で、前記塗布
用溶液に１５ｍｍ角のサファイア基板を浸漬し、毎秒
１．５ｍｍの一定速度で引き上げ、均一にＺｎＯゲル膜
を被覆し、該ゲル膜を３０分間乾燥後、大気中で７００
℃、１時間の熱処理を行い、ＺｎＯ薄膜を作製した。Then, in a dry glove box, a 15 mm square sapphire substrate was dipped in the coating solution and pulled up at a constant rate of 1.5 mm per second to uniformly coat the ZnO gel film, and the gel film was kept for 30 minutes. 700 in air after drying
A ZnO thin film was produced by performing heat treatment at 1 ° C. for 1 hour.
【００４１】尚、ＺｎＯ薄膜の膜厚を厚くするために、
浸漬−乾燥−熱処理を３回繰り返し、約１００ｎｍの膜
厚とした。In order to increase the thickness of the ZnO thin film,
The immersion-drying-heat treatment was repeated 3 times to obtain a film thickness of about 100 nm.
【００４２】得られたＺｎＯ薄膜をＸ線回折で測定する
とともに、走査型電子顕微鏡による観察を行った結果、
ＺｎＯ薄膜は表面が平滑で、柱状構造やクラックの無い
無配向の緻密な多結晶微粒子膜であることを確認した。The obtained ZnO thin film was measured by X-ray diffraction and observed by a scanning electron microscope.
It was confirmed that the ZnO thin film had a smooth surface and was a non-oriented dense polycrystalline fine particle film having no columnar structure or cracks.
【００４３】次に、センサ特性を測定するために、Ｚｎ
Ｏ薄膜表面にスパッタリング法にて白金または金から成
る０．１５ｍｍの電極間距離を有する電極パターンを形
成して検知電極とした。Next, in order to measure the sensor characteristics, Zn
An electrode pattern made of platinum or gold and having an interelectrode distance of 0.15 mm was formed on the surface of the O thin film by a sputtering method to form a detection electrode.
【００４４】以上のようにして得られたガスセンサ素子
を３５０℃に加熱しながら、窒素８０％、酸素２０％か
ら成る合成空気を基準とし、該合成空気に水素（Ｈ2 ）
ガスを１％加えた気体、及び前記合成空気に一酸化炭素
（ＣＯ）ガスを０．１％加えた気体、前記合成空気にメ
タン（ＣＨ4 ）ガスを１％加えた気体、前記合成空気に
プロパン（Ｃ3 Ｈ8 ）ガスを０．６％加えた気体の各評
価用雰囲気に変えた時、及びその後、前記各評価用雰囲
気を止めて再度基準の合成空気に戻した時の薄膜抵抗の
過渡的変化をそれぞれ測定した。その結果を図４に示
す。While heating the gas sensor element obtained as described above to 350 ° C., hydrogen (H 2 ) was added to the synthetic air based on synthetic air consisting of 80% nitrogen and 20% oxygen.
Gas containing 1% of gas, gas containing 0.1% of carbon monoxide (CO) gas to the synthetic air, gas containing 1% of methane (CH 4 ) gas to the synthetic air, and the synthetic air Of the thin film resistance when the atmosphere for each evaluation was changed to a gas to which propane (C 3 H 8 ) gas was added by 0.6%, and after that, the atmosphere for each evaluation was stopped and returned to the reference synthetic air again. Each transient change was measured. The result is shown in FIG.
【００４５】図４に顕著に現れているように、本発明の
ガスセンサは、一酸化炭素、メタンガス、プロパンガス
には感知せず薄膜抵抗が全く変化しないのに対して、と
りわけ水素ガスのみに選択的に感知することが薄膜抵抗
が短時間で大変小さくなるということから明らかとな
り、水素ガスに対しては高感度のガスセンサ特性を示す
ことが分かった。As clearly shown in FIG. 4, the gas sensor of the present invention does not detect carbon monoxide, methane gas, or propane gas and does not change the thin-film resistance at all. It became clear from the fact that the thin film resistance becomes very small in a short time, and it was found that the gas sensor characteristics show high sensitivity to hydrogen gas.
【００４６】また、図４からも明らかなように、本発明
のガスセンサは、数分で薄膜抵抗が初期値に戻ることか
ら、例えば、現在市販のＣＯセンサ等では、一旦ガスを
吸着してしまうとそのまま抵抗値が変わらず、再度セン
サ特性を回復させるために該センサには、使用温度より
高い温度に加熱して熱クリーニングする回路が設けられ
ており、センサ特性が回復するまですぐに繰り返し使用
することができないのに対して、本発明のガスセンサで
はすぐに繰り返し使用が可能となる。Further, as is apparent from FIG. 4, in the gas sensor of the present invention, the thin film resistance returns to the initial value within a few minutes, so that, for example, a currently commercially available CO sensor or the like will once adsorb the gas. In order to recover the sensor characteristics again, the sensor is equipped with a circuit for heating the sensor to a temperature higher than the operating temperature to perform thermal cleaning, and use it repeatedly until the sensor characteristics recover. However, the gas sensor of the present invention can be used immediately and repeatedly.
【００４７】尚、電気絶縁性基板として使用したサファ
イアの結晶面によるガス感応体のセンサー特性には、変
化は認められなかった。No change was observed in the sensor characteristics of the gas sensitive body due to the crystal plane of sapphire used as the electrically insulating substrate.
【００４８】実施例２ 実施例１と同様に、乾燥グルーブボックス内で、亜鉛ア
セチルアセトナート３ｍｍｏｌに２−メトキシエタノー
ル１００ｍｍｏｌ及びアセチルアセトン３ｍｍｏｌを添
加して反応溶液３を調製した。Example 2 In the same manner as in Example 1, reaction solution 3 was prepared by adding 100 mmol of 2-methoxyethanol and 3 mmol of acetylacetone to 3 mmol of zinc acetylacetonate in a dry groove box.
【００４９】その後、この反応溶液３を実施例１と同様
にして攪拌した後、実施例１と同一の部分加水分解用溶
液４を実施例１と同様にして、反応溶液３に注射器５で
ゆっくり滴下した後、１００℃の温度で１０時間加熱し
た。Thereafter, this reaction solution 3 was stirred in the same manner as in Example 1, and then the same partial hydrolysis solution 4 as in Example 1 was slowly added to the reaction solution 3 with a syringe 5 in the same manner as in Example 1. After the dropping, it was heated at a temperature of 100 ° C. for 10 hours.
【００５０】加熱終了後、室温まで冷却し、揮発した溶
媒に相当する量の２−メトキシエタノールを添加して濃
度調整を行い、塗布用溶液を作製した。After completion of heating, the mixture was cooled to room temperature, and 2-methoxyethanol in an amount corresponding to the volatilized solvent was added to adjust the concentration to prepare a coating solution.
【００５１】次に乾燥グローブボックス内で、前記塗布
用溶液に１５ｍｍ角のサファイア基板を浸漬し、実施例
１と同様にしてＺｎＯ薄膜を作製した。Then, a 15 mm square sapphire substrate was immersed in the coating solution in a dry glove box, and a ZnO thin film was prepared in the same manner as in Example 1.
【００５２】尚、ＺｎＯ薄膜の膜厚を厚くするために、
浸漬−乾燥−熱処理を３回繰り返し、実施例１と同様に
約１００ｎｍの膜厚を被着形成した。In order to increase the thickness of the ZnO thin film,
The immersion-drying-heat treatment was repeated 3 times to deposit a film having a thickness of about 100 nm in the same manner as in Example 1.
【００５３】得られたＺｎＯ薄膜を実施例１と同様にし
て評価したところ、ＺｎＯ薄膜の表面は平滑で、柱状構
造やクラックの無い無配向の緻密な多結晶微粒子膜であ
ることを確認した。The obtained ZnO thin film was evaluated in the same manner as in Example 1. As a result, it was confirmed that the surface of the ZnO thin film was a smooth, non-oriented dense polycrystalline fine particle film having no columnar structure or cracks.
【００５４】更に、この薄膜を８００℃、９００℃、１
０００℃でそれぞれ１時間熱処理したが、Ｘ線回折測定
の結果、いずれも結晶性は変わらず、また基板との反応
生成物等も認められなかった。Further, this thin film was formed at 800 ° C., 900 ° C., 1
Each sample was heat-treated at 000 ° C. for 1 hour, but as a result of X-ray diffraction measurement, the crystallinity did not change and no reaction product with the substrate was observed.
【００５５】また、センサ特性についても実施例１と同
様な方法で評価したところ、図４と同様のセンサ特性が
得られていることを確認した。The sensor characteristics were evaluated in the same manner as in Example 1, and it was confirmed that the sensor characteristics similar to those in FIG. 4 were obtained.
【００５６】[0056]
【発明の効果】叙上の如く、本発明のガスセンサ及びそ
の製造方法は、電気絶縁性の基板表面に、亜鉛成分を含
有したアルコキシドあるいは有機酸塩をエタノールアミ
ンを含有する有機溶媒に溶解し、加水分解した溶液を塗
布した後、加熱処理するゾルゲル法により形成したＺｎ
Ｏ薄膜から成るガス感応体と、ガス感応体に接続した一
対の検知電極から成ることから、密に重畳した粒径の小
さい均一なＺｎＯ薄膜から成るガス感応体が得られ、優
れた水素ガス選択性を有する再現性の良い高感度なガス
センサを得ることができる。As described above, the gas sensor and the method for producing the same according to the present invention include dissolving an alkoxide or organic acid salt containing a zinc component in an organic solvent containing ethanolamine on the surface of an electrically insulating substrate. Zn formed by the sol-gel method of applying heat treatment after applying the hydrolyzed solution
Since the gas sensitizer composed of the O thin film and the pair of sensing electrodes connected to the gas sensitizer are formed, the gas sensitizer composed of the dense ZnO thin films having a small particle size and closely overlapping each other can be obtained. It is possible to obtain a highly sensitive gas sensor having good reproducibility.
【図１】本発明のガスセンサのガス感応体を含む断面の
組織を示す電子顕微鏡写真である。FIG. 1 is an electron micrograph showing a structure of a cross section including a gas sensitive body of a gas sensor of the present invention.
【図２】本発明のガスセンサのガス感応体を成すＺｎＯ
薄膜の表面の結晶構造を示す電子顕微鏡写真であるFIG. 2 ZnO forming a gas sensitive body of the gas sensor of the present invention
It is an electron micrograph showing the crystal structure of the surface of the thin film.
【図３】本発明のガスセンサの製造方法の一実施例を説
明する塗布用溶液を調製するための装置の概略図であ
る。FIG. 3 is a schematic view of an apparatus for preparing a coating solution for explaining an example of the method for manufacturing a gas sensor of the present invention.
【図４】本発明のガスセンサのセンサ特性を示す図であ
る。FIG. 4 is a diagram showing sensor characteristics of the gas sensor of the present invention.
１ ＺｎＯ薄膜 ２ 電気絶縁性基板 ３ 反応溶液 ４ 部分加水分解用溶液 ５ 注射器 ６ 還流器 1 ZnO thin film 2 Electrically insulating substrate 3 Reaction solution 4 Partial hydrolysis solution 5 Syringe 6 Refluxer
Claims (2)
にゾルゲル法により形成したＺｎＯ薄膜から成るガス感
応体と、該ガス感応体に接続した一対の金（Ａｕ）また
は白金（Ｐｔ）から成る検知電極とから成ることを特徴
とするガスセンサ。1. An electrically insulating substrate, a gas responsive body comprising a ZnO thin film formed on the surface of the electrically insulating substrate by a sol-gel method, and a pair of gold (Au) or platinum (Pt) connected to the gas responsive body. A gas sensor comprising a detection electrode composed of.
トナートをＲｎＮ（ＣＨ2 ＣＨ2 ＯＨ）3-n （式中、Ｒ
はＨ、ＣＨ3 、Ｃ2 Ｈ5 のいずれか、ｎは０〜２のいず
れかの整数）で表されるエタノールアミンを含有する有
機溶媒に溶解し、加水分解した溶液を電気絶縁性基板表
面に塗布した後、酸化性雰囲気中で５００℃以上の温度
で熱処理してＺｎＯ薄膜を被着形成することを特徴とす
るガスセンサの製造方法。2. A zinc alkoxide or zinc acetylacetonate is added to RnN (CH 2 CH 2 OH) 3-n (wherein R
Is H, CH 3, C 2 H 5 either, n represents dissolved in an organic solvent containing ethanol amine represented by any integer) 0-2, hydrolyzed solution electrically insulating substrate surface A method for manufacturing a gas sensor, characterized in that the ZnO thin film is deposited by heat treatment in an oxidizing atmosphere at a temperature of 500 ° C. or higher after being applied to the substrate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13877594A JPH085591A (en) | 1994-06-21 | 1994-06-21 | Gas sensor and its manufacture |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13877594A JPH085591A (en) | 1994-06-21 | 1994-06-21 | Gas sensor and its manufacture |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH085591A true JPH085591A (en) | 1996-01-12 |
Family
ID=15229911
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP13877594A Pending JPH085591A (en) | 1994-06-21 | 1994-06-21 | Gas sensor and its manufacture |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH085591A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004256377A (en) * | 2003-02-27 | 2004-09-16 | Nippon Shokubai Co Ltd | Method of manufacturing metal oxide film |
| JP2006502943A (en) * | 2002-09-23 | 2006-01-26 | バイエル・マテリアルサイエンス・アクチェンゲゼルシャフト | Zinc oxide dispersion in anhydrous dispersion medium free of halogen |
| RU2509302C1 (en) * | 2012-10-15 | 2014-03-10 | Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Санкт-Петербургский государственный электротехнический университет "ЛЭТИ" им. В.И. Ульянова (Ленина)" | Method for obtaining gas-sensitive material based on zinc oxide to acetone vapours |
| EA034557B1 (en) * | 2018-05-21 | 2020-02-20 | Федеральное государственное бюджетное образовательное учреждение высшего образования "Саратовский государственный технический университет имени Гагарина Ю.А." | Method of manufacturing chemoresistor based on nanostructures of zinc oxide by electrochemical method |
| CN115676872A (en) * | 2022-08-25 | 2023-02-03 | 昆明理工大学 | High-flux preparation method, product and application of gas-sensitive material |
-
1994
- 1994-06-21 JP JP13877594A patent/JPH085591A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006502943A (en) * | 2002-09-23 | 2006-01-26 | バイエル・マテリアルサイエンス・アクチェンゲゼルシャフト | Zinc oxide dispersion in anhydrous dispersion medium free of halogen |
| JP2004256377A (en) * | 2003-02-27 | 2004-09-16 | Nippon Shokubai Co Ltd | Method of manufacturing metal oxide film |
| RU2509302C1 (en) * | 2012-10-15 | 2014-03-10 | Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Санкт-Петербургский государственный электротехнический университет "ЛЭТИ" им. В.И. Ульянова (Ленина)" | Method for obtaining gas-sensitive material based on zinc oxide to acetone vapours |
| EA034557B1 (en) * | 2018-05-21 | 2020-02-20 | Федеральное государственное бюджетное образовательное учреждение высшего образования "Саратовский государственный технический университет имени Гагарина Ю.А." | Method of manufacturing chemoresistor based on nanostructures of zinc oxide by electrochemical method |
| CN115676872A (en) * | 2022-08-25 | 2023-02-03 | 昆明理工大学 | High-flux preparation method, product and application of gas-sensitive material |
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