以直接模擬蒙地卡羅法模擬多蒸鍍源之物理氣相沉積過程

Abstract

在過去的數十年，電子束物理氣相沉積是一門被廣為發展的技術。應用此項技術的領域非常廣泛，特別是在半導體及航太工業，對鍍膜的應用實有著相當的貢獻。在這篇論文裡，首先介紹物理氣相沉積的基本理論，隨後敘述著合金沉積的概念，接著有幾個重要的課題值得我們去研究－基板上沉積的厚度及合金成分之均勻性。因此我們利用直接模擬蒙地卡羅法來模擬此項研究。為了了解流場中的傳輸現象，我們首先模擬一個簡單的案例，腔體內只有一個蒸鍍源，比較有考慮腔體內的背壓效應及沒有考慮腔體內的背壓效應的影響下，可以很明顯的看出腔體內的密度、溫度及速度變化之差異性。接著我們取金屬鈦、鋁、釩來做為蒸鍍物，利用多蒸鍍源之物理氣相沉積系統來沉積一個應用性極廣的鈦合金Ti6Al4V。藉著改變參數包括基板的高度、背壓及蒸鍍源之間的距離，基板上的沉積結果將告訴我們應如何調整才能得到令人可接受的厚度及合金成份之均勻性。

The technology of electron beam physical vapor deposition (EBPVD) has been highly developed in the past decades. It is widely used in many fields, especially in the semiconductor and aerospace industry. Its application really contributes to coating. In this study, the basic theory about electron beam physical vapor deposition will be introduced. The concepts about the deposition of alloy are then described subsequently. There are some important subjects we need to investigate, that is, the uniformity of deposited thickness and composition on the substrate. As a result, we use Direct Simulation Monte Carlo (DSMC) method to model this simulation conditions. In order to understand the transport phenomena, we simulate a simple case first, one source in the chamber. It is obvious to see the differences of variation of density, temperature, and velocity with and without considering background gas effect. Then we take metals of titanium, aluminum, vanadium as evaporant to coat with a widely applied titanium alloy Ti6Al4V using multiple sources EBPVD system. By changing parameters including altitude of the substrate, background pressure and distance between the sources, the deposited results on the substrate will show how we should adjust to obtain acceptable uniformity of thickness and composition.