臺灣博碩士論文加值系統

本文討論有機金屬化學氣相沉積熱壁式管狀反應器系統(hot-wall tubular reactor)，合成釕酸鍶(SrRuO3)及氧化釕(RuO2)薄膜之結構與性質，實驗以Ru(C5H5)2及Sr(DPM)2為前驅物。Ru(C5H5)2反應性遠較Sr(DPM)2來的強，昇華溫度亦較低，兩前驅反應性的差異可由沉積溫度上的差異得到證明，RuO2可於275℃的低溫下沉積，而SrO最低必須到410℃以上才有沉積發生。
同時通入Ru(C5H5)2及Sr(DPM)2於反應器中沉積之方法，受限於Ru及Sr 前驅物間反應性差距過大與兩固態前驅物昇華速率不同的問題影響。Ru前驅物反應性較強，主要沉積在管上游區域，而Sr前驅物則主要沉積於較下游之區域。Ru前驅物昇華速率較高亦使得沉積開始時，Ru沉積較快，前驅物也消耗較快，上面兩種原因均使得膜組成中Ru、Sr的比例不易控制。將沉積方法改成分別於不同沉積溫度個別沉積上RuO2及SrO薄膜之後，再於高溫下退火，利用固態擴散使RuO2及SrO膜層間相互擴散反應合成SrRuO3薄膜。
實驗結果顯示RuO2及SrO沉積的先後順序是個重要的因素，假如先沉積RuO2再沉積SrO(SrO/RuO2/SiO2/Si(100))，經過700℃退火，可合成單相的SrRuO3薄膜。相對的若是先沉積SrO再沉積RuO2(RuO2/ SrO /SiO2/Si(100))經過800℃退火，生成RuO2、SrRuO3及SrCO3混合相的沉積膜，這種不完全的固態反應是由於SrO無明顯的晶粒界較RuO2來的緻密，造成擴散的不易，RuO2薄膜有明顯的晶粒界，SrO沉積於RuO2之上容易經由晶粒界擴散(grain boundary diffusion)進行反應。RuO2薄膜為柱狀成長晶粒與晶粒間的縫隙較SrO來的大亦有利於進行擴散。
當SrRuO3薄膜Sr及Ru組成比(Ru/Sr+Ru)為0.5時，沉積膜室溫電阻率為910μΩ-cm，沉積膜電阻率隨膜中Ru的組成增加而降低，(Ru/Sr+Ru)=0.53時，沉積膜電阻率為470μΩ-cm，(Ru/Sr+Ru)=0.55時，則為280μΩ-cm。700℃退火之SrRuO3薄膜有最低的表面粗糙度，其均方根粗糙度約為21.9nm。
RuO2薄膜呈整齊的柱狀結構排列，沉積膜電阻率隨沉積溫度增加而降低，295℃沉積之RuO2薄膜室溫電阻率約252μΩ-cm， 355℃沉積之RuO2薄膜室溫電阻率約47μΩ-cm。結果說明在較高溫度下沉積的RuO2薄膜由於晶粒較大，使得沉積膜具有較少的晶粒界，降低電子通過晶界時晶界散射效應(grain boundary scattering)的影響，獲得較低的電阻率。晶粒尺寸隨沉積溫度增加而增加59nm(275 oC)~253nm(355oC)。RuO2薄膜表面粗糙度隨沉積溫度升高而增加，沉積溫度315℃的沉積膜有較低的表面均方根粗糙度約12.1nm，355℃之沉積膜表面均方根粗糙度約為35nm。

Synthesis of strontium ruthenate and ruthenium oxide thin films have been carried out in a hot-wall tubular reactor, using Ru(C5H5)2 and Sr(DPM)2 precursors. The reactivity of Ru(C5H5)2 is much higher than that of Sr(DPM)2, and so is its volatility. Growth temperature of ruthenium oxide can be as low as 275C, yet the lowest temperature for growing strontium oxide is 410C. The vast difference in growth temperatures makes the stoichiometric control of two oxides difficult if the simultaneous sublimation and deposition is applied. RuO2 tends to deposit at upstream positions, while SrO deposits at downstream positions. Therefore, RuO2 and SrO are sublimed and deposited at separate temperatures. It is of interest to find that the deposition sequence is an important factor. If the deposition sequence is RuO2-SrO, single phase of SrRuO3 can be synthesized after 700C annealing. On the other hand, if the sequence is SrO-RuO2, mixed phases of RuO2, SrRuO3 and SrCO3 after 800C annealing. The incomplete solid state reaction is owing to the dense SrO film that poses an obstacle for RuO2 diffusion, while the open microstructure of columnar RuO2 film is much easier for SrO diffusion.
The room-temperature film resistivity of SrRuO3 with Ru/(Sr+Ru)=0.5 is 910 -cm. The room-temperature film resistivity of SrRuO3 decreases with the increasing Ru content, 479 -cm at Ru/(Sr+Ru)=0.53, 280 -cm at Ru/(Sr+Ru)=0.55. The surface roughness of SrRuO3 film is minimum at 700C annealing temperature. The root mean square roughness of 700C is 21.9 nm.
The RuO2 thin film is featured with columnar microstructure. The resistivity of RuO2 thin film decreases with its growth temperature, the room temperature resistivity is 252 -cm for 295C-grown film and 47-cm for 355C-grown film. The reduction in resistivity is attributed to the less electron scattering at grain boundaries of large-grain film that is grown at high temperatures. The average grain size of RuO2 film increases with the deposition temperature, 59 nm (275C) to 253 nm (355C). The root mean square roughness of RuO2 generally increases with the deposition temperature, 12 nm (315C) to 35 nm (355C).

第一章 緒論…………………………………………………………1
第二章 文獻回顧……………………………………………………5
2-1. 底電極材料……………………………………………………5
2-2. 氧化釕之晶體性質……………………………………………7
2-3. 釕酸鍶晶體性質………………………………………………8
2-4. 釕酸鍶(SrRuO3)與氧化釕(RuO2)製備方式與性質研究……11
2-4-1. 釕酸鍶(SrRuO3)薄膜的合成與分析………………………11
2-4-2. 氧化釕薄膜的合成及分析…………………………………15
第三章 實驗方法及步驟……………………………………………19
3-1. 實驗藥品及規格………………………………………………19
3-2. 實驗設備與分析儀器…………………………………………21
3-2-1. 實驗裝置……………………………………………………21
3-2-2. 有機金屬化學氣相沉積熱壁系統簡介……………………22
3.3實驗操作步驟……………………………………………………24
3-3-1. 氧化釕薄膜合成……………………………………………24
3-3-2. 釕酸鍶薄膜合成……………………………………………25
3-4. 分析儀器………………………………………………………29
第四章 結果與討論…………………………………………………33
4-1. SrRuO3薄膜……………………………………………………33
4-1-1.SrRuO3薄膜X光繞射圖譜分析………………………………35
4-1-2.SrRuO3薄膜SEM電鏡分析……………………………………42
4-1-3.SrRuO3薄膜掃描式穿隧顯微鏡(STM/AFM)…………………51
4-1-4. SrRuO3薄膜電阻率量測……………………………………55
4-2. RuO2薄膜………………………………………………………60
4-2-1. RuO2薄膜顯微結構…………………………………………60
4-2-2.RuO2薄膜掃描式穿隧顯微鏡(STM/AFM)……………………67
4-2-3. RuO2薄膜電阻率……………………………………………71
第五章 結論…………………………………………………………74
參考文獻 ……………………………………………………………76
附錄 …………………………………………………………………79

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