The Preparation and characterization of the aluminum oxide thin films deposited on polyethylene terephthalate (PET) substrate by radio frequency magnetron sputtering

以塑膠材料作為平面顯示器的面板，不僅可以大大降低顯示器的重量及厚度，再加上塑膠材料本身具有的耐衝擊性、可撓曲性及可連續性製程的特色，使得研究可撓式塑膠平面顯示器成為目前發展的趨勢。但是使 用塑膠基板作為平面顯示器的面板要的解決重要問題就是水氣與氧氣的滲透，由於塑膠基板是無法有效抵擋水氣的滲透，容易造成內部顯示物質的損害，為了解決這個問題，通常會在塑膠基板上鍍上一層氣體阻隔層。 氧化鋁薄膜具有許多良好的性質；包含好的熱及化學穩定性，高硬度，高的阻隔及絕緣性，及具有良好的光學穿透性。本實驗使用氧化鋁靶材並利用射頻磁控濺鍍的方法，研究將氧化鋁薄膜沈積在PET塑膠基材上，改變製程參數分別為通入氧流量、工作腔壓，射頻功率及沈積時間，目的是為了要研究氧化鋁薄膜阻隔水氣的能力，期望將其應用在氣體阻隔層。 實驗的分析結果中得到，當沈積鍍膜條件為純氬氣的氣氛下、工作腔壓為2mtorr、射頻功率為4.9 W/cm2及鍍膜時間240分鐘時，可以得到最佳的氧化鋁薄膜性質及最低的水氣滲透率為0.564 g/m2-day，而未鍍膜的純PET基材，其水氣滲透率為7.255 g/m2-day，由實驗結果顯示，將氧化鋁薄膜沈積在PET塑膠基板上，確實可以有效阻隔水氣的滲透。Using plastic materials as the substrate of flat panel display (FPD) can not only decrease the weight and thickness of FPD; but also widen the application of FPD because plastic materials possess unique properties, such as high impact-resistance, flexibility, and the possibility for roll-to-roll coating techniques in mass production. Therefore, it becomes a trend in the present development to study the flexibility plastic flat panel display. However the high permeation of water vapors and oxygen through polymer substrate is an important problem in the flexible FPD applications. Plastic substrate most commercially used cannot resist the transmission of water vapor, which can easily cause a great damage inside the display. To resolve this problem, gas barrier layers can be deposited a on the plastic substrate. Aluminum oxide thin films possesses many good characteristics including the good thermal and chemical stability, the high hardness, the highly insulating capability which combined with good barrier properties, and the optical properties, in particular transparency. In this study, the Al2O3 thin film was deposited on polyethylene terephthalate (PET) plastic substrate by mean of an rf magnetron sputtering system equipped with an Al2O3 target. The purpose is to study the ability of water-resistance of Al2O3 thin film in terms of process parameters including oxygen flow rate, chamber pressure, rf power and deposition time, expecting for application as gas barrier layer. It showed that an excellent characteristics and minimum water vapor transmission rate (WVTR) — 0.564 g/m2-day of Al2O3 thin film was deposited when the rf power is 4.9 W/cm2, working pressure is 2 mtorr and the deposition time is 240 min under pure Argon gas. The WVTR of bare PET substrate is 7.255 g/m2-day. As a result of experiment, the deposition of Al2O3 thin film on PET plastic substrate indeed resists the water vapor transmission sufficiently.目錄 第一章 緒論 ----------------------------------------------1 1.1 前言 --------------------------------------------------1 1.2 研究目的 ---------------------------------------------3 第二章 文獻回顧 ------------------------------------------5 2.1 電漿-------------------------------------------------5 2.2 濺鍍理論 --------------------------------------------7 2.2.2 磁控濺鍍系統 ---------------------------------------10 2.2.3 自生偏壓( self-bias ) ------------------------------10 2.3 基材偏壓效應 ---------------------------------------12 2.4 薄膜沈積原理 ---------------------------------------13 2.4.1 薄膜沈積機構 ---------------------------------------13 2.4.2 薄膜微觀結構 ---------------------------------------14 2.5 電漿預處理基板表面 ---------------------------------15 2.6 氧化鋁薄膜之結構與特性 -----------------------------16 2.7 滲透理論 -------------------------------------------17 第三章 實驗方法與步驟 ----------------------------------31 3.1 氧化鋁靶材製備 -------------------------------------31 3.2 試片準備 -------------------------------------------32 3.3 薄膜沈積 -------------------------------------------33 3.3.1 鍍膜設備 ------------------------------------------33 3.3.2 射頻磁控濺鍍系統操作步驟 --------------------------34 3.3.3 鍍膜方式 ------------------------------------------36 3.4 分析儀器 -------------------------------------------36 3.4.1 透水測量儀 ----------------------------------------36 3.4.2 可見光光譜儀 --------------------------------------37 3.4.3 表面粗度儀 ----------------------------------------38 3.4.4 電子顯微鏡 ----------------------------------------38 3.4.5 原子力顯微鏡 --------------------------------------41 3.4.6 歐傑電子成分分析 ----------------------------------42 3.4.7 撓曲試驗 ------------------------------------------43 第四章 結果與討論 -----------------------------------------60 4.1 改變氧流量與工作腔壓 -------------------------------61 4.1.1 沈積速率之探討 ------------------------------------61 4.1.2 成分分析 ------------------------------------------62 4.1.3 掃瞄式電子顯微鏡（FE-SEM）及穿透式電子顯微鏡 （TEM）的分析 -----------------------------------------------64 4.1.4 表面形貌（AFM）的分析 -----------------------------66 4.1.5 可見光光譜儀的分析 --------------------------------67 4.1.6 透水測量儀的結果 ----------------------------------69 4.1.7 改變氧流量與工作腔壓的結論 ------------------------70 4.2 改變射頻功率 ---------------------------------------71 4.2.1 沈積速率之探討 ------------------------------------71 4.2.2 成分分析 ------------------------------------------72 4.2.3 掃瞄式電子顯微鏡（FE-SEM）及穿透式電子顯微鏡 （TEM）的分析 -----------------------------------------------72 4.2.4 表面形貌（AFM）的分析 -----------------------------73 4.2.5 可見光光譜儀的分析 --------------------------------74 4.2.6 透水測量儀的結果 ----------------------------------74 4.2.7 改變射頻功率的結論 --------------------------------75 4.3 改變鍍膜時間 ---------------------------------------76 4.3.1 沈積速率之探討 ------------------------------------76 4.3.2 掃瞄式電子顯微鏡（FE-SEM）的分析 ------------------76 4.3.3 表面形貌（AFM）的分析 -----------------------------77 4.3.4 可見光光譜儀的分析 --------------------------------77 4.3.5 透水測量儀的結果 ----------------------------------78 4.3.6 撓曲試驗結果 --------------------------------------78 第五章 結論 ----------------------------------------------139 參考資料 ---------------------------------------------------14

Experimental data confirm numerical modeling of the degradation process of magnesium alloys stents

Biodegradable magnesium alloy stents (MAS) could present improved long-term clinical performances over commercial bare metal or drug-eluting stents. However, MAS were found to show limited mechanical support for diseased vessels due to fast degradation. Optimizing stent design through finite element analysis (FEA) is an efficient way to improve such properties. Following previous FEA works on design optimization and degradation modeling of MAS, this work carried out an experimental validation for the developed FEA model, thus proving its practical applicability of simulating MAS degradation. Twelve stent samples of AZ31B were manufactured according to two MAS designs (an optimized one and a conventional one), with six samples of each design. All the samples were balloon expanded and subsequently immersed in D-Hanks’ solution for a degradation test lasting 14 days. The experimental results showed that the samples of the optimized design had better corrosion resistance than those of the conventional design. Furthermore, the degradation process of the samples was dominated by uniform and stress corrosion. With the good match between the simulation and the experimental results, the work shows that the FEA numerical modeling constitutes an effective tool for design and thus the improvement of novel biodegradable MAS