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一种铝掺杂氧化钨基的双选择性气敏传感器的制备方法 【EN】A kind of preparation method of the double selectivity gas sensor of aluminium doped tungsten oxide base

申请(专利)号:CN201910367558.6国省代码:天津 12
申请(专利权)人:【中文】河北工业大学【EN】Hebei University of Technology
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摘要:
【中文】本发明为一种铝掺杂氧化钨基的双选择性气敏传感器的制备方法。该方法利用磁控溅射法,将W靶溅射功率调至95‑110W,打开基片旋转控制开关,打开基片挡板,通氧溅射WO3薄膜,20min后,关闭氧气;将Al靶溅射功率调至40‑42W,溅射Al薄膜6‑10min;再通氧溅射WO3薄膜20min;制备出A‑B‑A三明治结构的薄膜。本发明的气敏传感器在不同工作温度下分别对甲醇与乙醇蒸汽有高选择性、高灵敏度和较短的响应‑恢复时间的优点。 【EN】Paragraph:The present invention is a kind of preparation method of the double selectivity gas sensor of aluminium doped tungsten oxide base.This method utilizes magnetron sputtering method, and W target sputtering power is adjusted to 95-110W, opens substrate rotary control switch, opens substrate baffle plate, leads to oxygen and sputters WO3Film after 20min, closes oxygen;Al target sputtering power is adjusted to 40-42W, sputtering Al films 6-10min;Lead to oxygen again and sputters WO3Film 20min;Prepare the film of A-B-A sandwich structure.Gas sensor of the invention has the advantages of highly selective, highly sensitive and shorter response-recovery time to methanol and alcohol vapour respectively at a temperature of different operating.Image:201910367558.GIF

主权项:
【中文】1.一种铝掺杂氧化钨基的双选择性气敏传感器的制备方法,其特征为该方法包括如下步骤: (1)清洗:用无水乙醇对硅基片和AlO陶瓷管进行擦洗; (2)靶材和衬底的安装:将磁控溅射所用的W靶材以及掺杂用的Al靶材分别安装在射频磁控阴极靶和直流磁控阴极靶上,将清洗好的硅基片和AlO陶瓷管安装在靶材正上方的衬底托上; (3)溅射前将系统抽真空直到系统的本底真空气压达到6×10-5×10 Pa; (4)抽完真空后,旋转挡板遮挡硅基片,通入氩气,使射频磁控阴极W靶和直流磁控阴极Al靶在氩气中同时预溅射10 min; (5)在反应溅射过程中,设定反应气体为高纯度的氧气、工作气体为高纯度的氩气; (6)溅射:通入混合气,旋开挡板,将W靶溅射功率调至95-110 W,溅射WO薄膜,20 min后,关闭氧气;将Al靶溅射功率调至40-42 W,溅射Al薄膜6-10 min;再恢复通氧,溅射WO薄膜20 min;溅射过程中,真空室内的气体压强保持为1.8-2.0 Pa;当为混合气体时,体积比为Ar:O =3:1-5:1; (7)薄膜热处理:溅射完成后,在真空腔体内将样品进行原位真空退火:在400-600 ℃下热处理1.5-3 h,在AlO陶瓷管表面形成所需的Al-WO薄膜,即形成气敏元件; (8)将气敏元件的金属丝焊接到六角底座上,形成铝掺杂的氧化钨基的气敏传感器。 【EN】1. a kind of preparation method of the double selectivity gas sensor of aluminium doped tungsten oxide base, it is characterized in that this method includes as follows Step: (1) it cleans: with dehydrated alcohol to silicon chip and AlOCeramic tube is cleaned; (2) W target used in magnetron sputtering and the Al target being doped with the installation of target and substrate: are separately mounted to radio frequency On magnetron cathode target and direct magnetic control cathode target, by cleaned silicon chip and AlOCeramic tube is mounted on the lining right above target On collet; (3) system is vacuumized until the base vacuum air pressure of system reaches 6 × 10 before sputtering-5×10Pa; (4) after exhausting vacuum, butterfly blocks silicon chip, is passed through argon gas, makes radio frequency magnetron cathode W target and direct magnetic control cathode Al target in argon gas simultaneously 10 min of pre-sputtering; (5) in reactive sputtering process, the argon gas that reaction gas is high-purity as the oxygen of high-purity, working gas is set; (6) it sputters: being passed through gaseous mixture, unscrew baffle, W target sputtering power is adjusted to 95-110 W, sputters WOFilm, 20 min Afterwards, oxygen is closed;Al target sputtering power is adjusted to 40-42 W, sputtering Al films 6-10 min;Restore logical oxygen again, sputters WOIt is thin 20 min of film;In sputtering process, the indoor gas pressure intensity of vacuum remains 1.8-2.0 Pa;When for mixed gas, volume ratio For Ar:O=3:1-5:1; (7) film is heat-treated: after the completion of sputtering, sample being carried out vacuum annealing in situ in vacuum cavity: at 400-600 DEG C Lower heat treatment 1.5-3 h, in AlOCeramic pipe surface forms required Al-WOFilm forms gas sensor; (8) gas sensor of the tungsten oxide base of aluminium doping will in the welded wire of gas sensor to hexagonal pedestal, be formed.


说明书

【中文】

一种铝掺杂氧化钨基的双选择性气敏传感器的制备方法

技术领域:

本发明属于一种气体传感器件,尤其适用于对于甲醇和乙醇具有双选择特性的WO3传感器。

背景技术:

近年来,醉酒驾车引发的交通事故频发,以及甲醇中毒时有发生。环境中过量的甲醇、乙醇气体会抑制人体中枢神经系统,导致一些并发症甚至休克。甲醇、乙醇都易燃,其蒸气与空气可形成爆炸性混合物,遇明火、高热能引起燃烧爆炸,与氧化剂接触发生化学反应或引起燃烧。随着社会环保意识逐步加强,气敏传感器已被广泛应用于国内的石油、化工、冶金、制药、食品、医疗、道路交通、市政燃气、数字矿山等行业。在各种类型的气敏传感器中,金属氧化物半导体气敏传感器因其灵敏度高、响应快、体积小、能耗与制造成本低、操作简单等特点,所以广泛应用于工业和民用自动控制系统,是当前最普遍应用、最具有实用价值的一类气敏传感器。材料的制备工艺对气敏性能影响很大,相应的形态有烧结型、厚膜型和薄膜型。目前,国内研制的气敏传感器存在选择性差,灵敏度低,响应-恢复时间长,未实现同一气敏元件对多气体具高选择性与灵敏度。由于磁控溅射技术具有高速、低温的特点,薄膜具有外延能力强、生长速度快、微观结构好、均匀性很好并且薄膜厚度容易控制等优点,尤为受人青睐。但是,利用溅射法制备薄膜,各项工艺参数的变化对薄膜的特性有显著影响,如:溅射功率、溅射气压、溅射时间等。因此,要制得特定性能的薄膜材料需要通过大量的研究、实验,才能确定适合溅射的工艺参数。

发明内容:

本发明针对现有技术中无法满足同一传感器对多气体具有选择性这一特点,提供一种铝掺杂氧化钨基的双选择性气敏传感器的制备方法,该方法利用磁控溅射法制备出A-B-A三明治结构的薄膜,得到在高低不同工作温度下分别对甲醇与乙醇具有选择性的气敏传感器。此气体传感器在不同工作温度下分别对甲醇与乙醇蒸汽有高选择性、高灵敏度和较短的响应-恢复时间。

本发明的技术方案为:

一种铝掺杂氧化钨基的双选择性气敏传感器的制备方法,该方法包括如下步骤:

(1)清洗:用无水乙醇对硅基片和Al2O3陶瓷管进行擦洗;

(2)靶材和衬底的安装:将磁控溅射所用的W靶材以及掺杂用的Al靶材分别安装在射频磁控阴极靶和直流磁控阴极靶上,将硅基片和Al2O3陶瓷管安装在靶材正上方的衬底托上;

(3)溅射前将系统抽真空直到系统的本底真空气压达到6×10-4-5×10-5Pa;

(4)预溅射;旋转挡板遮挡硅基片,通入氩气,使射频磁控阴极W靶和直流磁控阴极Al靶在氩气中同时预溅射10min;

(5)在反应溅射过程中,设定反应气体为高纯度的氧气、工作气体为高纯度的氩气;

(6)溅射:通入混合气,旋开挡板,将W靶溅射功率调至95-110W,溅射WO3薄膜,20min后,关闭氧气;将Al靶溅射功率调至40-42W,溅射Al薄膜6-10min;再恢复通氧,溅射WO3薄膜20min;溅射过程中,真空室内的气体压强保持为1.8-2.0Pa;当为混合气体时,体积比为Ar:O2=3:1-5:1;

(7)薄膜热处理:溅射完成后,在真空腔体内将样品进行原位真空退火:在400-600℃下热处理1.5-3h,在Al2O3陶瓷管表面形成所需的Al-WO3薄膜,即形成气敏元件;

所述的Al-WO3薄膜为WO3(厚度为190~210nm)-Al(厚度为80~120nm)-WO3(厚度为190~210nm)的三明治结构薄膜。

所述的制备方法还包括步骤(8):将气敏元件的金属丝焊接到六角底座上,形成铝掺杂的氧化钨基的气敏传感器。

所述的铝掺杂氧化钨基的双选择性气敏传感器的应用,用于检测甲醇或乙醇蒸气的存在;其中,当工作温度为18-25℃时,对100-1000ppm的乙醇蒸气进行检测;在工作温度34-60℃时,对100-1000ppm的甲醇蒸气检测。

本发明的实质性特点为:

本发明采用物理成膜法(溅射法)制备气敏元件,所制备出的气敏元件为具有A-B-A三明治结构的薄膜,在工作温度18-25℃下对乙醇有敏感特性,在工作温度34-60℃下对甲醇有敏感特性。可在混合有机蒸气中,利用同一气敏传感器通过调节工作加热电压分别检测出甲醇与乙醇蒸气的存在。

本发明的有益效果为:

(1)在市售的陶瓷上,用本发明所述的溅射方法制备WO3薄膜,成膜质量好、微观结构好、均匀性好。

(2)采用溅射工艺制备薄膜时,选择本发明的工艺参数,可实现同一气敏元件通过调节工作加热电压分别对甲醇与乙醇具有选择性,可以有效区分混合有机蒸气中的甲醇与乙醇。

本发明主要用途:利用不同工艺参数进行工艺组合创新,实现同一传感器分别检测甲醇与乙醇蒸气。一方面,在众多混合的有机蒸气中,根据加热电压和工作温度对应关系,调节工作温度可选择性地检测出甲醇与乙醇的存在;另一方面,在单一气体气氛中,将传感器工作温度调节到对应气体敏感的工作温度可分别检测甲醇与乙醇,可实现同一传感器分别对两种气体的检测。

附图说明:

图1所示为本发明中传感器的结构图;

其中,1-铂引线,2-金电极,3-敏感材料,4-陶瓷管,5-镍铬加热丝;

图2所示为测试电路图;

图3所示为气敏元件测试结果图,表明本发明所涉及的气敏元件对甲醇和乙醇的加热电压与灵敏度的关系。

图4所示为气敏元件加热电压与工作温度的对应关系图;

图5所示为样品经15万倍放大后的扫描电镜照片。

具体实施方式:

下面结合实施例对本发明做进一步描述。

本发明得到传感器的结构图如图1所示,传感器内部为在4-陶瓷管中放置5-镍铬加热丝,5-镍铬加热丝用以加热陶瓷管。在4-陶瓷管外部涂覆上3-敏感材料,2-金电极为4-陶瓷管上的两个金属点。将5-镍铬加热丝的两端和4-陶瓷管上的四条1-铂引丝分别与加热电路和测试电路相连接。

图2所示为测试电路图;其中,Rz为敏感元件电阻,R为负载电阻,R依据Rz大小进行选择。Vc为测试回路供给电压;Vout为输出的测试电压。Vh为加热回路的供给电压,依据需要的加热温度进行选择。通过该电路,给传感器中的电阻丝供电,使电阻丝发热,从而将热量通过Al2O3陶瓷管传导给陶瓷管表面材料。在测试气体气氛下,根据Rz的变化即可得知环境中测试气体的变化情况。

利用射频溅射法,选择合适的工艺参数(如溅射功率,退火温度,氩氧比等)在Al2O3陶瓷管表面制备WO3薄膜。Al2O3陶瓷管内置有加热丝,用以加热Al2O3陶瓷管。将加热丝和WO3膜上的铂金丝引出的电极分别与引出回路和测试电路相连接,利用WO3薄膜电阻随环境中测试气体浓度的变化而改变,便可测定测试气体是否存在。元件表现出了对甲醇与乙醇敏感的高选择性、高灵敏度和较短的响应-恢复时间的气敏特性。

气敏传感器的气敏特性通常用灵敏度来表征。灵敏度的定义为传感器在大气气氛中的电阻值Rs与传感器在一定浓度的被测气体气氛中的电阻值Rg与之比:

灵敏度的测试方法:通过给传感器中的电阻丝供电的方法,使电阻丝升温发热,从而将热量间接传导于Al2O3陶瓷管表面。将负载电阻R与传感器电阻Rz相串联,其两端供给测试电压Vc。取R两端的电压为输出电压Vout。传感器的电阻:在大气气氛下Rz=Rs,在测试气体气氛下,Rz=Rg。根据Rz的变化即可得知环境中测试气体的变化情况。

本发明采用溅射法制备出了对甲醇和乙醇敏感的双选择性气敏传感器,可在众多的混合气体中,通过调节工作温度分别检测出甲醇和乙醇的存在。它的工艺简单,具有良好的响应-恢复时间、高灵敏度和高选择性。

实施例1:

射频溅射法制备WO3薄膜:先用脱脂棉蘸取纯度大于99.7%的无水乙醇(分析纯)擦洗硅基片和Al2O3陶瓷管;

(1)将磁控溅射所用的99.9%纯度的W靶材以及掺杂用的99.9%纯度的Al靶材分别安装在射频磁控阴极靶和直流磁控阴极靶上。对系统进行抽真空,启动机械泵,机械泵对磁控溅射室进行抽气,当真空计指针达降至20Pa以下时,启动分子泵,利用分子泵进行抽真空,直至系统的气压达到6×10-4Pa。

(2)抽完真空后,旋转挡板遮挡硅基片,通入氩气,使射频磁控阴极W靶和直流磁控阴极Al靶在氩气中同时预溅射10min,以便除去靶表面的杂质及氧化物;打开氧气和氩气的气路阀门,向系统中通入体积比为:Ar:O2=3:1的气体,通过气体质量流量计控制真空室内的气体压力,使其保持在2.0Pa。

(3)将W靶溅射功率调至100W,打开基片旋转控制开关,打开基片挡板,通氧溅射WO3薄膜,秒表计时20min后,关闭氧气,增加氩气压力,使真空室内的气体压强恢复为2.0Pa。将Al靶溅射功率调至42W,溅射Al薄膜6min。再通氧(并调低氩气压力),使真空室内的气体压强为2.0Pa,混合气体的体积比为Ar:O2=3:1,溅射WO3薄膜20min。溅射后得到WO3(厚度约为200nm)-Al(厚度约为100nm)-WO3(厚度约为200nm)的三明治结构薄膜。

(4)溅射完成后,在真空腔体内(压强为2.0Pa)将样品进行原位真空退火。在400℃下退火3h后自然冷却至室内温度。在Al2O3陶瓷管表面形成所需的Al-WO3薄膜。

(5)Al2O3陶瓷管内置有加热丝,用以加热Al2O3陶瓷管。将加热丝和WO3膜上的铂金丝引出的电极分别与引出回路和测试电路(如图2所示)相连接,即形成铝掺杂的氧化钨基的气敏传感器。

(6)用HW-30A型气敏测试系统测定其气敏特性,测试结果如图3所示。采用日立S-4800扫描电子显微镜测定薄膜表面貌,测试结果如图5所示。

在不同加热电压下,传感器分别对1000ppm的甲醇与1000ppm的乙醇蒸气的灵敏度如

图3所示。传感器加热电压与工作温度的对应关系如图4所示。当本发明的气敏传感器工作温度为22℃时,其气敏测试结果如下:本项发明的气敏传感器对乙醇有单选择性,其对乙醇的灵敏度为412.53,响应时间为1s,恢复时间为4s,对甲醇等其他有机气体不敏感;当本发明的气敏传感器工作温度为36℃时,本项发明的气敏传感器对甲醇有单选择性,其对甲醇灵敏度为402.18,响应时间为1s,恢复时间为2s,对乙醇等其他有机气体不敏感。如图5所示,元件经400℃退火处理后出现较明显的晶粒、粒径在20-30nm之间、晶粒较小较均匀、具有疏松的结构,这样的结构在很大程度上提高了薄膜的表面积,有利于被测气体的吸附和扩散,从而提高了反应的灵敏性。

当前影响磁控溅射的主要因素有:

(1)氧氩比:氧氩比直接影响金属氧化物薄膜中金属原子和氧原子的化学比,如果控制的不好,将会造成大量的缺陷。在设计溅射装置时,应增加衬底表面氧分压,减少靶材附近的氧分压,以形成良好的金属氧化物薄膜。通过实验证明,向系统中通入体积比为:Ar:02=3:1-5:1的混合气体时,可以形成良好的WO3薄膜。

(2)本底真空度:真空室的残余气体会影响薄膜纯度。为了提高薄膜的纯度,必须尽量减少沉积到基片上的杂质的量。为了减少真空室的残余气体,本底真空度越高,就越有利于形成高纯度的WO3薄膜。通过实验证明,在真空度6×10-4Pa以下时,可以形成高纯度的WO3薄膜。

(3)溅射功率:溅射功率直接影响WO3的溅射速率和沉积速率,从而影响薄膜的质量。溅射功率与溅射装置和靶的大小有关。溅射功率常选择在40-100W之间。

本发明通过一系列工艺参数的组合创新,本发明实现同一传感器在工作温度18-25℃下对1000ppm的乙醇有敏感特性,在工作温度34-60℃下对1000ppm的甲醇有敏感特性。由于分子的吸附能力与极性成正比,甲醇的极性大于乙醇的极性,甲醇的吸附能力大于乙醇的吸附能力。在室温下,温度达不到气敏传感器对甲醇的工作温度,所以气敏传感器对乙醇敏感;升高工作温度,乙醇在气敏传感器表面解除吸附,温度达到检测甲醇的所需工作温度,气敏传感器对甲醇敏感。

实施例2:

射频溅射法制备WO3薄膜:先用脱脂棉蘸取纯度大于99.7%的无水乙醇(分析纯)擦洗硅基片和Al2O3陶瓷管;

(1)将磁控溅射所用的99.9%纯度的W靶材以及掺杂用的99.9%纯度的Al靶材分别安装在射频磁控阴极靶和直流磁控阴极靶上。对系统进行抽真空,启动机械泵,机械泵对磁控溅射室进行抽气,当真空计指针达降至20Pa以下时,启动分子泵,利用分子泵进行抽真空,直至系统的气压达到6×10-4Pa。

(2)抽完真空后,旋转挡板遮挡硅基片,通入氩气,使射频磁控阴极W靶和直流磁控阴极Al靶在氩气中同时预溅射10min,以便除去靶表面的杂质及氧化物;打开氧气和氩气的气路阀门,向系统中通入体积比为:Ar:O2=4:1的气体,通过气体质量流量计控制真空室内的气体压力,使其保持在2.0Pa。

(3)将W靶溅射功率调至100W,通氧溅射WO3薄膜20min后,关闭氧气,增加氩气压力,使真空室内的气体压强恢复为2.0Pa。将Al靶溅射功率调至42W,溅射Al薄膜10min。再通氧(并调低氩气压力),使真空室内的气体压强为2.0Pa,混合气体的体积比为Ar:O2=4:1,溅射WO3薄膜20min。

(4)溅射完成后,在真空腔体内将样品进行原位真空退火。先400℃恒温退火1.5h自然冷却至室内温,再进行600℃恒温退火1.5h自然冷却至室内温度。在Al2O3陶瓷管表面形成所需的Al-WO3薄膜。

(5)Al2O3陶瓷管内置有加热丝,用以加热Al2O3陶瓷管。将加热丝和WO3膜上的铂金丝引出的电极分别与引出回路和测试电路(如图2所示)相连接,即形成铝掺杂的氧化钨基的气敏传感器。

(6)用HW-30A型气敏测试系统测定其气敏特性。

当本发明的气敏传感器工作温度为25℃时,其气敏测试结果如下:本项发明的气敏传感器对1000ppm的乙醇有单选择性,其对乙醇灵敏度为145.58,响应时间1s,恢复时间为10s,对1000ppm的甲醇等其他有机气体不敏感;当本发明的气敏传感器工作温度为55℃时,本项发明的气敏传感器对1000ppm的甲醇有单选择性,其对甲醇灵敏度高达687.62,响应、恢复时间均为1s,对1000ppm的乙醇等其他有机气体不敏感。

实施例3:

射频溅射法制备WO3薄膜,步骤如实施例1,不同之处为:向系统中通入体积比为:Ar:02=2:1的气体。实验结果失败,气敏传感器对1000ppm的甲醇与1000ppm的乙醇均不敏感。原因是靶材附近的氧分压较高,造成薄膜表面大量的缺陷,无法形成良好的金属氧化物薄膜。

实施例4:

射频溅射法制备WO3薄膜,步骤如实施例1,不同之处为:溅射Al薄膜时通氧气。实验结果失败,气敏传感器只对1000ppm的乙醇敏感,对1000ppm的甲醇不敏感。

综上所述,本发明采用分步溅射的方法,得到的铝掺杂氧化钨基的双选择性气敏传感器,可用于调节工作加热电压在1.25-1.75V之间时(对应工作温度18-25℃),气敏元件对乙醇蒸气敏感,而对甲醇蒸气不敏感;当调节工作加热电压在2.75-5.00V之间时(对应工作温度34-60℃),气敏元件对甲醇蒸气敏感,而对乙醇蒸气不敏感。可实现通过同一气敏传感器,完成了利用调节工作加热电压分别检测出甲醇与乙醇蒸气的存在的目标。

以上实施例仅为举例说明,非起限制作用。任何未脱离本发明精神与范畴,而对其进行的等效修改或变更,均应包含于本申请的权利要求范围之中。

本发明未尽事宜为公知技术。

【EN】

A kind of preparation method of the double selectivity gas sensor of aluminium doped tungsten oxide base

Technical field:

The invention belongs to a kind of gas sensing device, it is particularly suitable for that there are double selection characteristics for methanol and ethyl alcohol

WO3Sensor.

Background technique:

In recent years, the traffic accident that drunk driving causes takes place frequently and methanol poisoning happens occasionally.Excessive first in environment

Alcohol, alcohol gas can inhibit human central nervous system, and some complication is caused even to be suffered a shock.Methanol, ethyl alcohol are all inflammable, steam

Gas and air can form explosive mixture, and chance open fire, high thermal energy cause combustion explosion, contacts and chemically react with oxidant

Or cause to burn.As social environment consciousness is gradually reinforced, gas sensor be widely used in domestic petroleum, chemical industry,

The industries such as metallurgy, pharmacy, food, medical treatment, road traffic, municipal combustion gas, digital mine.In various types of gas sensors

In, Metal Oxide Semiconductor Gas Sensing sensor because its high sensitivity, response is fast, small in size, energy consumption and manufacturing cost are low, operation

The features such as simple is current most commonly used, most practical valence so being widely used in industry and civilian automatic control system

A kind of gas sensor of value.The preparation process of material is very big on air-sensitive performance influence, and corresponding form has slug type, thick-film type

And film-type.Currently, there are poor selectivities for the gas sensor of domestic development, sensitivity is low, and the response-recovery time is long, unreal

Existing same gas sensor has highly selective and sensitivity to more gases.Since magnetron sputtering technique has the characteristics that high speed, low temperature,

It is excellent that film has that extension capability is strong, the speed of growth is fast, microstructure is good, uniformity is fine and film thickness is easy to control etc.

Point, is especially favored by people.But film is prepared using sputtering method, the variation of various process parameters has significantly the characteristic of film

It influences, such as: sputtering power, sputtering pressure, sputtering time.Therefore, the thin-film material that particular characteristic is made is needed by big

Quantifier elimination, experiment just can determine that the technological parameter for being suitble to sputtering.

Summary of the invention:

The present invention for be unable to satisfy in the prior art same sensor to more gases have the characteristics that selectively this, provide

A kind of preparation method of the double selectivity gas sensor of aluminium doped tungsten oxide base, this method prepare A- using magnetron sputtering method

The film of B-A sandwich structure obtains at a temperature of height different operating respectively to methanol air-sensitive selective with ethyl alcohol

Sensor.This gas sensor at a temperature of different operating respectively to methanol and alcohol vapour have it is highly selective, highly sensitive and

The shorter response-recovery time.

The technical solution of the present invention is as follows:

A kind of preparation method of the double selectivity gas sensor of aluminium doped tungsten oxide base, this method comprises the following steps:

(1) it cleans: with dehydrated alcohol to silicon chip and Al2O3Ceramic tube is cleaned;

(2) installation of target and substrate: W target used in magnetron sputtering and the Al target being doped with are separately mounted to

On radio frequency magnetron cathode target and direct magnetic control cathode target, by silicon chip and Al2O3Ceramic tube is mounted on the substrate bracket right above target

On;

(3) system is vacuumized until the base vacuum air pressure of system reaches 6 × 10 before sputtering-4-5×10-5Pa;

(4) pre-sputtering;Butterfly blocks silicon chip, is passed through argon gas, makes radio frequency magnetron cathode W target and direct magnetic control cathode

Al target in argon gas simultaneously pre-sputtering 10min;

(5) in reactive sputtering process, the argon that reaction gas is high-purity as the oxygen of high-purity, working gas is set

Gas;

(6) it sputters: being passed through gaseous mixture, unscrew baffle, W target sputtering power is adjusted to 95-110W, sputters WO3Film,

After 20min, oxygen is closed;Al target sputtering power is adjusted to 40-42W, sputtering Al films 6-10min;Restore logical oxygen, sputtering again

WO3Film 20min;In sputtering process, the indoor gas pressure intensity of vacuum remains 1.8-2.0Pa;When for mixed gas, volume

Than for Ar:O2=3:1-5:1;

(7) film is heat-treated: after the completion of sputtering, sample being carried out vacuum annealing in situ in vacuum cavity: in 400-600

1.5-3h is heat-treated at DEG C, in Al2O3Ceramic pipe surface forms required Al-WO3Film forms gas sensor;

The Al-WO3Film is WO3(with a thickness of 190~210nm)-Al (with a thickness of 80~120nm)-WO3(with a thickness of

190~210nm) Sandwich film.

The preparation method further includes step (8): by the welded wire of gas sensor to hexagonal pedestal, forming aluminium

The gas sensor of the tungsten oxide base of doping.

The application of the double selectivity gas sensor of the aluminium doped tungsten oxide base, for detecting methanol or alcohol vapor

Presence;Wherein, when operating temperature is 18-25 DEG C, the alcohol vapor of 100-1000ppm is detected;In operating temperature

At 34-60 DEG C, the methanol vapor of 100-1000ppm is detected.

Substantive distinguishing features of the invention are as follows:

The present invention prepares gas sensor using physical film deposition method (sputtering method), and prepared gas sensor is with A-B-

The film of A sandwich structure has sensitivity characteristic to ethyl alcohol at 18-25 DEG C of operating temperature, to first at 34-60 DEG C of operating temperature

Alcohol has sensitivity characteristic.It can be examined respectively using same gas sensor by adjusting work heating voltage in mixing organic vapor

Measure the presence of methanol and alcohol vapor.

The invention has the benefit that

(1) on commercially available ceramics, WO is prepared with sputtering method of the present invention3Film, quality of forming film is good, microcosmic knot

Structure is good, uniformity is good.

(2) when preparing film using sputtering technology, technological parameter of the invention is selected, it can be achieved that same gas sensor passes through

Adjusting work heating voltage has selectivity to methanol and ethyl alcohol respectively, can effectively distinguish the methanol that is mixed in machine steam with

Ethyl alcohol.

Main application of the present invention: process combination innovation is carried out using different technical parameters, realizes that same sensor is examined respectively

Survey methanol and alcohol vapor.On the one hand, it in numerous mixed organic vapors, is closed according to heating voltage and operating temperature are corresponding

System adjusts the presence that operating temperature optionally detects methanol and ethyl alcohol;It on the other hand, will in pure gas atmosphere

The operating temperature that senor operating temperature is adjusted to corresponding gas sensitization can detect methanol and ethyl alcohol, it can be achieved that same sensing respectively

The device detection to two kinds of gas respectively.

Detailed description of the invention:

Fig. 1 show the structure chart of sensor in the present invention;

Wherein, 1- platinum lead, 2- gold electrode, 3- sensitive material, 4- ceramic tube, 5- nickel chromium triangle heater strip;

Fig. 2 show test circuit diagram;

Fig. 3 show gas sensor test result figure, shows gas sensor according to the present invention to methanol and ethyl alcohol

The relationship of heating voltage and sensitivity.

Fig. 4 show the corresponding relationship of gas sensor heating voltage and operating temperature;

Fig. 5 show sample through 150,000 times of amplified stereoscan photographs.

Specific embodiment:

The present invention is described further below with reference to embodiment.

The present invention obtains the structure chart of sensor as shown in Figure 1, sensor internal is to place 5- nickel chromium triangle in 4- ceramic tube

Heater strip, 5- nickel chromium triangle heater strip is to heating ceramic pipe.It is applied outside 4- ceramic tube and is covered with 3- sensitive material, 2- gold electrode is 4-

Two metal dots on ceramic tube.By four 1- platinum on the both ends and 4- ceramic tube of 5- nickel chromium triangle heater strip draw silk respectively with heating

Circuit is connected with test circuit.

Fig. 2 show test circuit diagram;Wherein, Rz is sensing element resistance, and R is load resistance, and R is carried out according to Rz size

Selection.Vc is test loop service voltage;Vout is the test voltage of output.Vh is the service voltage of heating circuit, and foundation needs

The heating temperature wanted is selected.By the circuit, powers to the resistance wire in sensor, so that resistance wire is generated heat, thus by hot

Amount passes through Al2O3Ceramic tube is conducted to ceramic tube surfacing.In the case where testing gas atmosphere, according to the variation of Rz it can be learnt that ring

The situation of change of gas is tested in border.

Using radio frequency sputtering method, select suitable technological parameter (such as sputtering power, annealing temperature, argon oxygen ratio etc.) in Al2O3

Ceramic pipe surface prepares WO3Film.Al2O3Ceramic tube is built-in with heater strip, to heat Al2O3Ceramic tube.By heater strip and WO3

The electrode that platinum wire on film is drawn is connected with extraction circuit and test circuit respectively, utilizes WO3Film resistor is in environment

The variation of testing gas concentration and change, can measure test gas whether there is.Element shows quick with ethyl alcohol to methanol

The gas-sensitive property of highly selective, the highly sensitive and shorter response-recovery time of sense.

The gas-sensitive property of gas sensor is usually characterized with sensitivity.The definition of sensitivity is sensor in air atmosphere

In resistance value Rg in certain density tested gas atmosphere of resistance value Rs and sensor with the ratio between:

The test method of sensitivity: the method by powering to the resistance wire in sensor makes resistance wire heating fever, from

And heat is conducted indirectly in Al2O3Ceramic pipe surface.Load resistance R and sensor resistance Rz are connected in series, both ends supply is surveyed

Try voltage Vc.The voltage for taking the both ends R is output voltage Vout.The resistance of sensor:In air atmosphere

Lower Rz=Rs, in the case where testing gas atmosphere, Rz=Rg.According to the variation of Rz it can be learnt that testing the variation feelings of gas in environment

Condition.

The present invention has prepared the double selectivity gas sensor to methanol and alcohol sensible using sputtering method, can be numerous

Mixed gas in, detect the presence of methanol and ethyl alcohol respectively by adjusting operating temperature.Its simple process has good

The response-recovery time, high sensitivity and highly selective.

Embodiment 1:

Radio frequency sputtering method prepares WO3Film: first dip purity greater than 99.7% dehydrated alcohol with absorbent cotton (analysis is pure)

Clean silicon chip and Al2O3Ceramic tube;

(1) by the W target of 99.9% purity used in magnetron sputtering and the Al target for 99.9% purity being doped with point

It is not mounted on radio frequency magnetron cathode target and direct magnetic control cathode target.System is vacuumized, mechanical pump, mechanical pump pair are started

Magnetron sputtering chamber is evacuated, and gauge pointer starts molecular pump up to when being down to 20Pa or less, take out using molecular pump true

Sky, until the air pressure of system reaches 6 × 10-4Pa。

(2) after exhausting vacuum, butterfly blocks silicon chip, is passed through argon gas, makes radio frequency magnetron cathode W target and direct magnetic control

Cathode Al target in argon gas simultaneously pre-sputtering 10min, to remove the impurity and oxide on target surface;Open oxygen and argon gas

Gas circuit valve, volume ratio is passed through into system are as follows: Ar:O2The gas of=3:1 is controlled in vacuum chamber by gas mass flow meter

Gas pressure, keep it in 2.0Pa.

(3) W target sputtering power is adjusted to 100W, opens substrate rotary control switch, open substrate baffle plate, lead to oxygen sputtering

WO3Film after manual time-keeping 20min, closes oxygen, increases argon pressure, revert to the indoor gas pressure intensity of vacuum

2.0Pa.Al target sputtering power is adjusted to 42W, sputtering Al films 6min.Lead to oxygen (and turning down argon pressure) again, makes in vacuum chamber

Gas pressure intensity be 2.0Pa, the volume ratio of mixed gas is Ar:O2=3:1 sputters WO3Film 20min.WO is obtained after sputtering3

(thickness is about 200nm)-Al (thickness is about 100nm)-WO3The Sandwich film of (thickness is about 200nm).

(4) after the completion of sputtering, sample is carried out vacuum annealing in situ by (pressure 2.0Pa) in vacuum cavity.At 400 DEG C

Room temperature is naturally cooled to after lower annealing 3h.In Al2O3Ceramic pipe surface forms required Al-WO3Film.

(5)Al2O3Ceramic tube is built-in with heater strip, to heat Al2O3Ceramic tube.By heater strip and WO3Platinum on film

The electrode that silk is drawn is connected with extraction circuit and test circuit (as shown in Figure 2) respectively, that is, forms the tungsten oxide base of aluminium doping

Gas sensor.

(6) its gas-sensitive property is measured with HW-30A type air-sensitive test macro, test results are shown in figure 3.Using Hitachi S-

4800 scanning electron microscope measure film surface looks, and test results are shown in figure 5.

Under different heating voltage, sensor is respectively to the sensitivity of the alcohol vapor of the methanol of 1000ppm and 1000ppm

Such as

Shown in Fig. 3.Sensor heating voltage and the corresponding relationship of operating temperature are as shown in Figure 4.When air-sensitive of the invention passes

When sense device working temperature is 22 DEG C, test result is as follows for air-sensitive: the gas sensor of this invention has mono-selectivity to ethyl alcohol,

It is 412.53, response time 1s, recovery time 4s to the sensitivity of ethyl alcohol, and to methanol etc., other organic gas are unwise

Sense;When gas sensor operating temperature of the invention is 36 DEG C, the gas sensor of this invention has mono-selectivity to methanol,

It is 402.18, response time 1s, recovery time 2s to methanol sensitivity, and to ethyl alcohol etc., other organic gas are insensitive.

As shown in figure 5, element through 400 DEG C annealing after occur obvious crystal grain, partial size between 20-30nm, crystal grain it is smaller compared with

Uniformly, with loose structure, such structure largely improves the surface area of film, is conducive to tested gas

Absorption and diffusion, to improve the sensitivity of reaction.

The current principal element for influencing magnetron sputtering has:

(1) O2 to Ar ratio: O2 to Ar ratio directly affects the chemical ratio of metallic atom and oxygen atom in metal-oxide film, if

What is controlled is bad, it will causes a large amount of defect.When designing sputtering equipment, Ying Zengjia substrate surface partial pressure of oxygen reduces target

Neighbouring partial pressure of oxygen, to form good metal-oxide film.It is experimentally confirmed, volume ratio is passed through into system are as follows: Ar:

02When the mixed gas of=3:1-5:1, good WO can be formed3Film.

(2) background vacuum: the residual gas of vacuum chamber will affect film purity.In order to improve the purity of film, it is necessary to

Reduce the amount for depositing to the impurity on substrate to the greatest extent.In order to reduce the residual gas of vacuum chamber, background vacuum is higher, more has

Conducive to the WO for forming high-purity3Film.It is experimentally confirmed, in vacuum degree 6 × 10-4When Pa or less, high-purity can be formed

WO3Film.

(3) sputtering power: sputtering power directly affects WO3Sputter rate and deposition rate, to influence the matter of film

Amount.Sputtering power is related with the size of sputtering equipment and target.Sputtering power often selects between 40-100W.

The present invention passes through the combined innovation of series of process parameter, and the present invention realizes same sensor in operating temperature 18-

There is sensitivity characteristic to the ethyl alcohol of 1000ppm at 25 DEG C, has sensitivity characteristic to the methanol of 1000ppm at 34-60 DEG C of operating temperature.

Since the adsorption capacity of molecule is directly proportional to polarity, the polarity of methanol is greater than the polarity of ethyl alcohol, and the adsorption capacity of methanol is greater than second

The adsorption capacity of alcohol.At room temperature, gas sensor is not achieved to the operating temperature of methanol, so gas sensor is to second in temperature

Alcohol is sensitive;Increased operating temperatures, ethyl alcohol desorb on gas sensor surface, and temperature reaches the required work temperature of detection methanol

Degree, gas sensor are sensitive to methanol.

Embodiment 2:

Radio frequency sputtering method prepares WO3Film: first dip purity greater than 99.7% dehydrated alcohol with absorbent cotton (analysis is pure)

Clean silicon chip and Al2O3Ceramic tube;

(1) by the W target of 99.9% purity used in magnetron sputtering and the Al target for 99.9% purity being doped with point

It is not mounted on radio frequency magnetron cathode target and direct magnetic control cathode target.System is vacuumized, mechanical pump, mechanical pump pair are started

Magnetron sputtering chamber is evacuated, and gauge pointer starts molecular pump up to when being down to 20Pa or less, take out using molecular pump true

Sky, until the air pressure of system reaches 6 × 10-4Pa。

(2) after exhausting vacuum, butterfly blocks silicon chip, is passed through argon gas, makes radio frequency magnetron cathode W target and direct magnetic control

Cathode Al target in argon gas simultaneously pre-sputtering 10min, to remove the impurity and oxide on target surface;Open oxygen and argon gas

Gas circuit valve, volume ratio is passed through into system are as follows: Ar:O2The gas of=4:1 is controlled in vacuum chamber by gas mass flow meter

Gas pressure, keep it in 2.0Pa.

(3) W target sputtering power is adjusted to 100W, leads to oxygen and sputters WO3After film 20min, oxygen is closed, increases Ar Pressure

Power makes the indoor gas pressure intensity of vacuum revert to 2.0Pa.Al target sputtering power is adjusted to 42W, sputtering Al films 10min.Lead to again

Oxygen (and turning down argon pressure), makes the indoor gas pressure intensity 2.0Pa of vacuum, and the volume ratio of mixed gas is Ar:O2=4:1,

Sputter WO3Film 20min.

(4) after the completion of sputtering, sample is subjected to vacuum annealing in situ in vacuum cavity.First 400 DEG C of cycle annealing 1.5h

Indoor Temperature is naturally cooled to, then carries out 600 DEG C of cycle annealing 1.5h and naturally cools to room temperature.In Al2O3Ceramic pipe surface shape

At required Al-WO3Film.

(5)Al2O3Ceramic tube is built-in with heater strip, to heat Al2O3Ceramic tube.By heater strip and WO3Platinum on film

The electrode that silk is drawn is connected with extraction circuit and test circuit (as shown in Figure 2) respectively, that is, forms the tungsten oxide base of aluminium doping

Gas sensor.

(6) its gas-sensitive property is measured with HW-30A type air-sensitive test macro.

When gas sensor operating temperature of the invention is 25 DEG C, test result is as follows for air-sensitive: the gas of this invention

Dependent sensor has mono-selectivity to the ethyl alcohol of 1000ppm, is 145.58 to ethyl alcohol sensitivity, response time 1s, recovery time

For 10s, to methanol of 1000ppm etc., other organic gas are insensitive;When gas sensor operating temperature of the invention is 55 DEG C

When, the gas sensor of this invention has mono-selectivity to the methanol of 1000ppm, to methanol high sensitivity up to 687.62, rings

Answer, recovery time is 1s, to ethyl alcohol of 1000ppm etc., other organic gas are insensitive.

Embodiment 3:

Radio frequency sputtering method prepares WO3Film, step such as embodiment 1, difference are as follows: volume ratio is passed through into system are as follows:

Ar:02The gas of=2:1.Experimental result failure, gas sensor are unwise to the methanol of 1000ppm and the ethyl alcohol of 1000ppm

Sense.The reason is that the partial pressure of oxygen near target is higher, a large amount of defect of film surface is caused, good metal oxide can not be formed

Film.

Embodiment 4:

Radio frequency sputtering method prepares WO3Film, step such as embodiment 1, difference are as follows: lead to oxygen when sputtering Al films.It is real

Result failure is tested, gas sensor is insensitive to the methanol of 1000ppm only to the alcohol sensible of 1000ppm.

In conclusion method of the present invention using substep sputtering, the double selectivity air-sensitive of obtained aluminium doped tungsten oxide base

Sensor, (corresponding 18-25 DEG C of operating temperature), gas sensor when can be used for adjusting work heating voltage between 1.25-1.75V

It is sensitive to alcohol vapor, and it is insensitive to methanol vapor;(the corresponding work when adjusting work heating voltage between 2.75-5.00V

Make 34-60 DEG C of temperature), gas sensor is sensitive to methanol vapor, and insensitive to alcohol vapor.It can be achieved to pass by same air-sensitive

Sensor completes the existing target for detecting methanol and alcohol vapor respectively using adjusting work heating voltage.

Above embodiments are by way of example only, non-to provide constraints.It is any without departing from spirit of that invention and scope, and to it

The equivalent modifications or change of progress, shall be included in the scope of claims of this application.

Unaccomplished matter of the present invention is well-known technique.

图1
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