電漿CVD法沉積半導性薄膜及其在化學感測器應用

Plasma CVD-deposited Semiconductive Thin Films and Their Application of Chemical Sensors

李明旭(Ming-Shu Li)

指導教授 ： 陳克紹

大同大學/工程學院/材料工程學系所/博士(2006年)

摘要

本研究藉由感測元件的設計，改變元件的電極結構、幾何圖形(pattern)、尺寸(size)、寬度(width)與間距(inter-distance)等，用以增進其有效電極幅(W)及縮小電極間距(I)，以提升感測的效果。以濕度感測層的製作為例，將配製好之有機電解質NaSS (sodium styrenesulfonate)單體溶液，利用spin coating塗佈於所設計的電極上，再以UV光照射接枝聚合。由結果可知，在相對濕度RH 40~90%變化下，以具較大W/I值之圓形感測電極具有較低且呈現約3 orders的感濕阻抗變化。本研究也以電漿沉積及表面接枝聚合來改質無機基材的表面結構與特性，如有機性質、結構組成、親疏水性、官能基特性、及導電性等。以四甲基錫(tetramethyltin, TMT, Sn(CH3)4)和氧氣(O2 gas)混合為反應單體，利用低溫電漿化學氣相沉積PECVD(plasma enhanced chemical vapor deposition)法沉積氧化錫(SnOx)有機薄膜，此有機膜含有過氧化物或自由基，可再後續藉由UV光接枝功能性高分子，藉以改變基材表面的特性。有機共軛半導性高分子近年來有愈來愈多的需求被應用於電子、光學、顯示元件及感測器方面。利用PECVD法，分別以乙炔(C2H2)、乙炔/氮氣(C2H2/N2)及乙炔/氨氣(C2H2/NH3)之含氮混合物(nitrogen-containing mixtures)沉積薄膜。當氮氣或氨氣與乙炔混合通入反應腔體，電漿沉積膜包含所有混合單體的元素，其不但呈現出C–H鍵結，同時也顯現出含氮官能基(nitrogen functionalities)的特性。[N]/[C]原子比例因通入單體組成不同而改變，以氨氣混合乙炔達最大值0.12。膜之阻抗在室溫及大氣環境下量測是接近於絕緣體(over 108 Ω)範圍，而其也不具有濕度感應性。在膜吸附酒精氣體(vapor)之後，不論沉積所用混合單體的組成，膜之阻抗下降至約106 Ω，有3 order阻抗之變化，並在20秒內達到穩定值。

關鍵字

微電子感測元件 ； 電極圖形設計 ； 氧化錫(SnOx)有機薄膜 ； UV光接枝聚合 ； 乙炔及含氮混合物

並列摘要

In this study, the design of the sensitive device is employed to improve the sensitive effects by varying the construction, pattern, size, width, and inter-distance of the electrode. The purpose is to increase the effective width and reduce the inter-distance of the electrodes. For fabricating the humidity sensitive layer, the monomeric solution of organic electrolyte NaSS was spin-coated on the designed electrodes with different patterns and then exposed to UV-light to induce grafting polymerization. From the results, the circular sensitive electrode with higher W/I value has the lower impedance and shows about 3 orders of change in the impedance for the variation of relative humidity from 40 to 90%. The plasma deposition and surface grafting polymerization have been used to modify the surface structure and properties of inorganic substrates such as organic nature, structural constitution, hydrophilicity, functional groups, and conductivity. In this study, tin oxide (SnOx) organic-like thin films were deposited by plasma enhanced chemical vapor deposition (PECVD) of tetramethyltin (TMT) and O2 gas mixtures at low temperature. The organic-like thin films containing peroxides or free radicals can be subsequently grafted hydrophilic polymer acrylamide (AAm) by UV-induced grafting polymerization. Plasma-deposited thin films were prepared from PECVD of acetylene (C2H2), acetylene/nitrogen (C2H2/N2), or acetylene/ammonia (C2H2/NH3). When N2 or NH3 was mixed with C2H2 in the feed, the films were identified to contain all elements of the mixture and the properties of the films were implied by the C–H bonds and nitrogen functionalities. The resistance of the thin films measured at ambient environment is over 108 Ω near electric insulator and independent of humidity. It is found that the resistance of the thin film sensors prepared from C2H2, C2H2/N2, and C2H2/NH3 is distinctly decreased by over 2 orders of magnitude by the adsorption of ethanol vapor.

並列關鍵字

Microelectronic sensitive device ； Electrode pattern design ； SnOx organic-like films ； UV-induced grafting polymerization ； Acetylene and nitrogen-containing mixtures

參考文獻

Chapter I

[7] V.Casey , M.I.Stephenson, J.Phys.D: Appl. Phys. 23 (1990) 1212.

[11] N. Inagaki, Y. Hashimoto, J. Polym. Sci.: Polym. Lett. 24 (1986) 447.

[14] M. Millard, in J. R. Hollahan and A. T. Bell (ed.), Techniques and Applications of Plasma Chemistry. Wiley, New York, (1974), Chapter 5.

[19] J. Watson, The tin oxide gas sensor and its applications. Sens. Actuators 5 (1984) 29-42.