利用直接模擬蒙地卡羅法模擬直線蒸鍍源有機發光二極體沉積過程之研究

Abstract

近年來，由於有機發光二極體(Organic Light-emitting Diodes, OLED)具有自發光性、廣視角、高對比、低耗電、高反應速率等優點，有機發光二極體的崛起逐漸受到學術界與產業界的高度重視。現今，如何於大尺寸製程中精確控制沉積層的均勻性且兼顧沉積速率，已成為業界首要任務之一。除了直接進行製程實驗以外，如何利用模擬計算軟體事先進行模擬獲得最佳化製程條件與腔體設計以大輻降低研發成本，並加速研發進程是很重要的。因為在真空腔體內是屬於自由分子流的狀況，所以我們使用直接模擬蒙地卡羅法去模擬有機發光二極體沉積的過程，直接模擬蒙地卡羅法是一種粒子法，只要模擬的粒子數夠龐大，即可得到與真實相符合的模擬結果，並用此來解出波茲曼方程式。 在論文中，我們使用了平行化混和非結構網格DSMC的程式(名為PDSC++)，利用PDSC++去模擬複雜形狀的真空腔體沉積的過程。本研究的目的為改變蒸鍍源孔徑大小對基板的均勻度與蒸鍍速率的影響，在一開始原型設計中，先透過實驗與模擬進行比對取得模擬所需參數，在取得參數後發現原型的薄膜不均勻度高達6.99%，於是將原型進行優化設計，透過三次的優化設計最終將不均勻度降低至目標< 2%。 首先我們將透過沉積的薄膜厚度及孔洞直徑的比例來換算並重新調整，並以平均值作為一個調整的基準將正負離差縮小，透過調整孔徑大小來控制蒸鍍的速率。首先，第一次的優化調整先是粗略的依照比例計算進行調整，先將不均勻度降至3%以內在進行微調，經過首次的優化之後得到2.65%的不均勻度已經大幅降低至3%以內，後面兩次將進行微調，最終將薄膜不均勻度降至1.93%符合不均勻度< 2%的目標。

Recently, organic light emitting diode (OLED) has a self-luminous, wide viewing angle, high contrast, low power consumption, high reaction rate, etc. OLED has become an important research topic by the attention of academia and industry, gradually. Nowadays, how to precisely control uniformity of the substrate deposition layer and deposition rate in large size manufacturing process, it has become one of the industry’s top priority. In addition to experiments, how to use simulation software to simulate in advance to obtain an optimal process conditions and cavity chamber design to reduce high development cost and accelerate the development process are important. Therefore, the OLED deposition process is simulated by direct simulation Marte Carlo (DSMC) method while the vacuum chamber is with free-molecular flow. The direct simulation Monte Carlo (DSMC) method is simulating the Boltzmann equation using a large number of pseudo particles, which each particle represents the large number of real molecules. In this thesis, we use a previously developed parallel and unstructured grid direct simulation Monte Carlo code named PDSC++ to simulate the deposition process within a vacuum chamber with a complex geometry. The purpose of this study is uniformity and deposition rate at the substrate by changing the diameter of holes. First, we calculate the deposition thin film and hole size scale to adjust the hole size, and the average value as a deviation of plus or minus adjustment benchmarks. To control the deposition rate by adjust the size of apecture. First, the first optimization adjustment is rough caculation according to aperture proportion. We reduce non-uniformity to less than 3% first. After the first optimization to give 2.65% of the non-uniformity has been significantly reduced to less than 3%. So we do fine-tuning for last two. The non-uniformity of film was eventually reduced to 1.93% and within the non-uniformity < 2%.