溶液製程沉積過渡金屬/氧化物薄膜之研究

Abstract

薄膜材料在工業上有廣泛的應用，其中金屬與金屬氧化物薄膜更多元地應用在能源產業與半導體工業上。過渡金屬及其氧化物之性質會因為製程上的不同而有所差異，例如形貌與結晶度。因此在發展嶄新製程，合成新潁的金屬或金屬氧化物薄膜時，薄膜本身性質的探討與沉積機制的研究極為重要。了解所製備材料之特性與沉積過程的機制，有助於未來在材料應用上的評估。 本研究以溶液製程為主，包含無電鍍與溶膠凝膠法，以新潁的溶液配方成份，分別製備釕/二氧化釕(Ru/RuO2)、二氧化銥(IrO2)、以及氧化鈮(Nb2O5)薄膜。對薄膜進行材料分析，包括X光繞射分析(XRD)、X光光電子光譜分析(XPS)、掃描式電子顯微鏡觀察(SEM)等。此外，紫外可見光光譜(UV-Vis)以及X光吸收光譜(XAS) 被利用來檢測溶液，分析過渡金屬離子與確認其氧化態。最後探討無電鍍的沉積機制。 利用無電鍍法沉積釕/二氧化釕薄膜，可沉積出非晶形的釕/二氧化釕複合薄膜。探討其溶液之沉積機制，發現機制為一先氧化後還原之機制。釕之三價前驅物，會先氧化成八價釕之過渡狀態，再還原至金屬態之釕。另外，在發展無電鍍沉積二氧化銥薄膜時，所沉積之薄膜為非晶形的二氧化銥薄膜，沉積機制為一直接氧化過程，銥之三價前驅物，和氧化劑反應，產生銥四價的二氧化銥薄膜。而在氧化鈮薄膜的合成中，以溶膠凝膠法製備搭配旋轉塗佈法，輔以高溫退火，製備出結晶之氧化鈮薄膜。在分析氧化鈮薄膜特性上，同時以電化學和紫外可見光吸收光譜(UV-Vis)做即時檢測，探討氧化鈮薄膜在外加電壓下之即時吸收光譜，以評估其在電致變色上之性質。 本研究以開發新潁成份的無電鍍液，沉積金屬與金屬氧化物薄膜，對鍍液與鍍層進行材料分析，並探討沉積機制。開發新潁配方之無電鍍溶液時，建立完整之分析方法，檢測液體溶液與固體鍍層。

Thin film materials are widely employed in many industries. In particular, metal and metal oxide thin films have received considerable attentions because they show promising potentials in energy technologies and semiconductor manufacturing. The physical and chemical properties of metals and metal oxides vary greatly and different preparation routes lead to distinct morphology and crystallinity. In the development of novel metal or metal oxide thin films, it is extremely important to characterize the thin films and explore the deposition mechanism. Better understanding of film properties and relevant deposition mechanisms are necessary to promote the further applications. This study mainly focuses on the solution processes, including electroless plating and sol-gel process. We developed new solution compositions, preparing various thin films including ruthenium/ruthenium oxide (Ru/RuO2), iridium oxide (IrO2), and niobium oxide (Nb2O5). X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscope (SEM) were employed for thin film characterization. In addition, UV-Vis spectra and X-ray absorption spectroscopy (XAS) were conducted for solution analyses, determining the identity of the metal ion species and their corresponding oxidation states. An amorphous Ru thin film was obtained by electroless plating. The electroless process revealed an oxidative-reductive mechanism, in which the precursor Ru(III) was oxidized to Ru(VIII) first, followed by its subsequent reduction to metallic Ru and Ru(IV). In addition, in developing the IrO2 by electroless plating, the deposit was confirmed as an amorphous IrO2 thin film. And the deposition mechanism was a straightforward oxidation process, which means that the Ir(III) precursor is oxidized to Ir(IV), forming an IrO2 thin film. Furthermore, crystalline Nb2O5 thin film was fabricated by a spin-coating sol-gel process with an annealing treatment. In-situ UV-Vis spectroelectrochemstry was performed to inspect the electrochromic properties of the Nb2O5 thin film. In summary, this study develops electroless formula with new ingredients to deposit metal and metal oxide thin films. Characterization for both electroless solution and deposited film are performed, and the deposition mechanisms are proposed and discussed.