以分子動力學模擬鋁沉積在銅基材之研究

Molecular Dynamic Simulation of Al Clusters Deposition on Cu Substrate

鄭易承(Yi-Cheng Zheng)

指導教授 ： 陳興松

國立虎尾科技大學/工程學院/材料科學與綠色能源工程研究所/碩士(2012年)

摘要

本文以FCC結構之銅晶體作為基板、Al為沉積原子，運用分子動力學的方法來模擬研究Al原子沉積在銅基板後表面的形貌，和Al原子在沉積過程中的物理機制。本研究的模擬參數包含Al沉積原子的入射速率、入射動能、入射角度和基板溫度。研究採用週期邊界法來模擬整個真實的系統大小及以Gear’s五階預測修正法來計算系統原子位移後的位置、速度和加速度，並利用多體勢能的緊束法(Tight-binding)勢能函數與Verlet鄰近表列的演算式，來計算原子的交互作用力。
由模擬的結果可以得知，在原子入射能量較小狀態時，沉積速率對於薄膜的結構並無明顯的影響；且在此條件下的沉積過程中Al原子處於低入射動能(10eV)狀態，即使能量和溫度升高Al原子的沉積薄膜的覆蓋率仍無明顯改變。此外模擬結果亦顯示，薄膜的成長方式是屬於核成長型，隨著溫度的上升原子擴散程度也會增加。
本文最後並提出以分子動力學方法模擬研究原子沉積的瓶頸及需要改進的方向，期望後續研究能提高此模擬法的效能，使其將來能有助於相關業界的參數設定和相關設備的設計。

關鍵字

分子動力學 ； 週期邊界 ； 緊束法勢能函數 ； Verlet鄰近表列法

並列摘要

In this study, the copper crystal with face center cubic (FCC) structure serves as the substrate and the aluminum (Al) as the deposited atoms. Molecular dynamics was employed to investigate the surface topography of the Cu structure which was covered by the Al atoms, and to study the physical mechanism of the process. The simulation parameters include incident energy, incident angle, system temperature, and deposition rate. This study used periodic boundary condition to simulate the real system and Gear’s predictor-corrector algorithms to calculate the position, velocity, and acceleration of the atoms after each time step. The second-moment approximation of the tight-binding (TB-SMA) many body potential was employed to calculate interaction force between the atoms.
According to the simulation results, the influence of deposition rate on the deposited thin film was not significant when the atomic incident energy was low. And, the Al atoms were low incident energy (10eV) at deposition process in this situation. Even if the energy and the temperature increased, the coverage rate of Al atoms film was not significant change. In addition, the simulation results also show, the growth type of film was belong to nuclear growth type. And when the temperature risen the atomic diffusion degree was increased.
Finally, the bottlenecks and the improve method of the molecular dynamics simulation are proposed and suggested for accelerating the development and application of this simulation method.

並列關鍵字

Molecular dynamics ； periodic boundary condition ； tight-binding

參考文獻

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[21]朱清俊，2006，”應用分子動力學研究奈米薄膜沉積之力學行為與性質”，國立成功大學機械工程學系，博士論文。

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