JPH0458905B2

JPH0458905B2 -

Info

Publication number: JPH0458905B2
Application number: JP20667485A
Authority: JP
Inventors: Yoshiaki Okayama
Original assignee: Nohmi Bosai Ltd
Current assignee: Nohmi Bosai Ltd
Priority date: 1985-09-20
Filing date: 1985-09-20
Publication date: 1992-09-18
Also published as: JPS6267437A

Description

[Detailed description of the invention]

〔産業上の利用分野〕この発明は、シラン系ガスなどの特殊ガスを選
択的に検出できるガス検出素子とその製造方法に
関するものである。〔従来技術〕モノシラン（SiH₄）、ジクロルシラン（SiH₂
Cl₂）、トリクロルシラン（SiHCl₃）、ホスフイン
（PH₃）、ジボラン（B₂H₆）やアルシン（AsH₃）
など、空気などの他の気体と接触混合すると数％
の濃度で自然発火する特殊ガスを検出することが
できるガス検出素子として、本発明者は、先に特
願昭58−157931号（特開昭60−50446号）によつ
て酸化第２すず（SnO₂）と白金（Pt）とオキシ
塩化アンチモン（SbOCl）を組成物としてシラン
系ガス雰囲気で後処理した金属酸化物半導体のガ
ス検出素子を、また特願昭59−98818号（特開昭
60−243548号公報）によつてSnO₂とパラジウム
（Pd）とアンチモン化合物（Sb化合物）を組成物
としシラン系ガス雰囲気で後処理した金属酸化物
半導体のガス検出素子を提案している。ところで、これら従来のガス検出素子を濃度が
10ppmのSiH₄ガスにさらしたときのSN比と応答
時間は、前者のSnO₂−Pt−SbOC1系ガス検出素
子ではSN比が10程度、応答時間は150〜180秒程
度であり、後者のSnO₂−Pd−Sb化合物系ガス検
出素子ではSN比が５程度、応答時間は150秒前後
であるという特性を有している。〔目的と解決手段〕本発明は、SN比が良好で応答時間の早い、し
かも低濃度の特殊ガスを選択的に検出できるガス
検出素子とその製造方法を目的とするもので、酸
化第２スズ（SnO₂）を主材、白金（Pt）とパラ
ジム（Pd）とを触媒、アンチモン化合物（Sb化
合物）を安定材としてPt／Sn＝0.5〜８モル％、
Pd／Sn＝0.1〜８モル％、Sb／Sn＝０〜８モル
％の組成比を有し、20〜400ppmのシラン系ガス
雰囲気で処理してなる金属酸化物半導体と、この
金属酸化物半導体を200〜400℃に加熱する加熱手
段とからなることを特徴とするものである。また、次の工程の製造方法を特徴とするもので
ある。 SnO₂に塩化パラジウム（PdCl₂）溶液と塩化
白金酸（H₂PtCl₆）溶液とをPd／Sn＝0.1〜８
モル％、Pt／Sn＝0.5〜８モル％となるように
加えて分散させ、乾燥する。の試料にSb化合物をSb／Sn＝0.5〜８モル
％となるように加えて混合する。の試料に有機溶剤を加えてペースト状に
し、１対の電極が設けられた絶縁体に塗布し乾
燥する。の素子を、600〜850℃の大気またはアンチ
モン酸化ガスの雰囲気中で５〜30分間焼成す
る。の素子を、CVD法により20〜400ppmのシ
ラン系ガスで５〜30分間処理する。の素子を加熱してエージングする。〔実施例〕以下、この発明のガス検出素子とその製造方法
について実施例により説明する。次の製造方法により表に示す実施例２〜８のガ
ス検出素子を制作した。なお、各実施例において
ガス検出素子は８個ずつ製作した。準備段階として、塩化パラジウム（PdCl₂）に
0.2％の塩酸水溶液を加えてPdCl₂溶液を作成する
とともに、塩化白金酸（H₂PtCl₆・6H₂Ｏ）に純
水を加えてH₂PtCl₆溶液を作成する。まず、酸化第２スズ（SnO₂）にPdCl₂溶液を
Pd／Sn＝0.1〜８モル％となるように加え、さら
にH₂PtCl₆溶液をPt／Sn＝0.5〜８モル％となる
ように加えて混合水溶液を作成する。次に、この混合水溶液を超音波かくはん機によ
つてかくはんしてPdとPtを良く分散させる。そ
の後この分散混合水溶液を真空凍結乾燥器にセツ
トし、−40℃で急速凍結乾燥させる。そして、この乾燥試料にオキシ塩化アンチモン
（SbOCl）をSb／Sn＝0.5〜８モル％となるよう
に加え、乳鉢で約30分間混合して混合試料を得
る。なお、実施例２〜10における各混合試料のPd，
Pt，SbとSnの組成比は表に示す通りである。この混合試料に有機溶剤であるイソプロピルア
ルコールを加えてペースト状の混合試料とし、こ
れを１対の電極を有するアルミナ磁器管上に１対
の電極間を覆うように塗布し、その後自然乾燥す
る。 [Industrial Field of Application] The present invention relates to a gas detection element that can selectively detect special gases such as silane gases, and a method for manufacturing the same. [Prior art] Monosilane (SiH ₄ ), dichlorosilane (SiH ₂
Cl ₂ ), trichlorosilane (SiHCl ₃ ), phosphine (PH ₃ ), diborane (B ₂ H ₆ ) and arsine (AsH ₃ ).
etc., several percent when mixed with other gases such as air.
As a gas detection element capable of detecting a special gas that spontaneously combusts at a concentration of A metal oxide semiconductor gas detection element made of a composition of SnO ₂ ), platinum (Pt), and antimony oxychloride (SbOCl) and post-treated in a silane-based gas atmosphere was also proposed in Japanese Patent Application No. 59-98818 (Japanese Patent Application No.
No. 60-243548) proposes a metal oxide semiconductor gas detection element that has a composition of SnO ₂ , palladium (Pd), and an antimony compound (Sb compound) and is post-treated in a silane gas atmosphere. By the way, these conventional gas detection elements are
When exposed to 10 ppm SiH ₄ gas, the former SnO ₂ -Pt-SbOC1 gas detection element has an SN ratio of about 10 and a response time of about 150 to 180 seconds, while the latter SnO The ₂ -Pd-Sb compound gas detection element has the characteristics of an SN ratio of about 5 and a response time of about 150 seconds. [Objectives and Solutions] The present invention aims to provide a gas detection element that has a good signal-to-noise ratio, has a quick response time, and can selectively detect low concentration special gases, and a method for manufacturing the same. (SnO ₂ ) as main material, platinum (Pt) and palladium (Pd) as catalyst, antimony compound (Sb compound) as stabilizer, Pt/Sn = 0.5 to 8 mol%,
A metal oxide semiconductor having a composition ratio of Pd/Sn=0.1 to 8 mol% and Sb/Sn=0 to 8 mol% and treated in a silane gas atmosphere of 20 to 400 ppm, and this metal oxide semiconductor and heating means for heating the temperature to 200 to 400°C. Further, the present invention is characterized by a manufacturing method including the following steps. Add palladium chloride (PdCl ₂ ) solution and chloroplatinic acid (H ₂ PtCl ₆ ) solution to SnO ₂ at Pd/Sn=0.1-8.
It is added and dispersed so that Pt/Sn=0.5 to 8 mol% and dried. An Sb compound is added to the sample so that Sb/Sn=0.5 to 8 mol% and mixed. An organic solvent is added to the sample to form a paste, which is applied to an insulator provided with a pair of electrodes and dried. The device is fired for 5 to 30 minutes in air or antimony oxidation gas atmosphere at 600 to 850°C. The device is treated with 20 to 400 ppm silane gas for 5 to 30 minutes by CVD method. The device is heated and aged. [Example] Hereinafter, the gas detection element of the present invention and the manufacturing method thereof will be explained with reference to Examples. Gas detection elements of Examples 2 to 8 shown in the table were manufactured using the following manufacturing method. Note that eight gas detection elements were manufactured in each example. As a preparatory step, palladium chloride (PdCl ₂ )
A 0.2% aqueous hydrochloric acid solution is added to create a PdCl ₂ solution, and pure water is added to chloroplatinic acid (H ₂ PtCl ₆ .6H ₂ O) to create an H ₂ PtCl ₆ solution. First, add PdCl ₂ solution to stannic oxide (SnO ₂ ).
A mixed aqueous solution is prepared by adding Pd/Sn=0.1 _to 8 mol% and further adding _H2PtCl6 solution to Pt/Sn=0.5 to 8 mol%. Next, this mixed aqueous solution is stirred using an ultrasonic stirrer to disperse Pd and Pt well. Thereafter, this dispersed mixed aqueous solution is placed in a vacuum freeze dryer and rapidly freeze-dried at -40°C. Then, antimony oxychloride (SbOCl) is added to this dry sample so that Sb/Sn=0.5 to 8 mol%, and mixed in a mortar for about 30 minutes to obtain a mixed sample. In addition, Pd of each mixed sample in Examples 2 to 10,
The composition ratios of Pt, Sb and Sn are shown in the table. Isopropyl alcohol, which is an organic solvent, is added to this mixed sample to form a paste-like mixed sample, which is applied onto an alumina porcelain tube having a pair of electrodes so as to cover between the pair of electrodes, and then air-dried.

【表】【table】

〔effect〕

この発明によれば、特殊ガスに対してSN比が
高くかつ応答時間の早い、しかも低濃度の特殊ガ
スを選択的に検出可能なガス検出素子とその製造
方法が得られる効果がある。 According to the present invention, it is possible to obtain a gas detection element that has a high signal-to-noise ratio and a quick response time for special gases, and can selectively detect low concentration special gases, and a method for manufacturing the same.

[Brief explanation of the drawing]

図はSiH₄ガスに対する応答特性の代表例であ
る。 The figure shows a typical example of response characteristics to SiH ₄ gas.

Claims

[Claims] 1. Pt/Sn with stannic oxide as the main material, platinum and palladium as a catalyst, and an antimony compound as a stabilizer.
= 0.5 to 0.8 mol%, Pd/Sn = 0.1 to 8 mol%,
Sb/Sn has a composition ratio of 0.5 to 8 mol%, and 25 to
A metal oxide semiconductor treated in a 400ppm silane gas atmosphere and the above metal oxide semiconductor
A gas detection element comprising a heating means for heating to 200 to 400°C. 2. Pd/Sn=0.1-8 mol%, Pt/Sn=
The first step is adding an antimony compound to a concentration of 0.5 to 8 mol%, dispersing, and drying, and adding an antimony compound to the sample prepared in the first step.
The second step is to add and mix Sb/Sn so that it is 0.5 to 8 mol%, and the sample prepared in the second step is made into a paste by adding an organic solvent, and this is applied to an insulator with a pair of electrodes. a third step in which the element prepared in the third step is baked for 5 to 30 minutes in the air at 600 to 850°C or an atmosphere of antimony oxidation gas; and a fourth step in which the aged element is 20~ by CVD method
The fifth step is treatment with 400ppm silane gas for 5 to 30 minutes.
A method for producing a gas detection element, comprising: a sixth step of heating and aging the element produced in the fifth step. 3 The antimony oxidation gas atmosphere is created by placing an antimony compound of 1×10 ^-9 to 4.5×10 ^-8 mol/cm ³ in terms of the number of moles of antimony trioxide in an atmosphere at 600 to 850°C for 5 to 60 minutes. A method for manufacturing a gas detection element according to claim 2, wherein the gas detection element is produced.