Argon離子轟擊引致銅濺現象之分子動力學模擬

Abstract

本文是運用分子動力學模擬於真空下，單顆氬離子轟擊銅靶材濺鍍之現象。用原子嵌入法(EAM)與ZBL勢能分別來模擬銅原子間，及離子與銅之間的作用。入射離子的能量範圍在100到5000電子伏特，角度為0到70度。單就研討離子轟擊的效應，我們設其起始溫度為絕對零度，以免除銅晶格間的震動所產生的影響。從模擬結果中得知，當入射離子能量為5000與1000電子伏特，在入射角分別為45及20度時，有相對極大的銅濺量；100電子伏特的銅濺量隨角度的變化量不大。銅濺量大致隨著入射能量增大而增加。角度的分佈呈非等方向性，且大致集中在四個主要方向，沿著入射離子投影方向的分佈量會相對較多。此外，能量分佈範圍隨著入射角度增加，並且大致集中在2.5到12.5電子伏特。

Sputtering of copper metal targets (100) due to bombardment of a single argon ion at vacuum condition is simulated using molecular dynamic simulation. A simplified EAM (embedded atom model) is used to mimic Cu-Cu interaction, while ZBL model is used to model Cu-Ar+ interaction. Energies and angles of incident argon ions and are in the range of 100-5,000 eV and 0-70°, respectively. Initial temperature of the solid copper is assumed to be 0°K, which is used intentionally to study the atom sputtering solely due to ion bombardment without the effects of lattice vibration of the solid copper. Results of sputtering yield show that it is maximized at angle of 20° (1st max.) and 45° (2nd max.) for higher incident ion energy (1,000 and 5,000 eV), while it is relatively uniform at all angles for lower incident ion energy (100 eV). Sputtering yield increases with increasing incident ion energy as expected. Sputtered copper atoms show strongly anisotropic angular distribution, where they concentrate in four major directions along the lattice arrangement. Elongation of the distribution in the direction of incident ion is clear for incident angle larger than or equal to 5°. In addition, most probable energy of sputtered atoms occurs in the range of 2.5-12.5 eV, which generally increases with increasing incident angle of ion, although the energy distribution is broadened for larger incident angle.