【作者】 蒋志勇；

【导师】 郑忠；

【作者基本信息】 重庆大学 ， 材料科学与工程， 2008， 硕士

【摘要】 薄膜材料的发展对微电子,微机械等高科技领域的发展有着重要影响,而薄膜的原子尺度的生长过程将影响薄膜材料的各种应用性能,因此关于薄膜生长过程的开展了大量从实验到理论的研究工作。随着计算机科学等新型科学技术的发展,计算机模拟可以从原子尺度模拟薄膜形成的动态过程,解释实验观察到各种现象,分析各种实验条件对成膜的影响,为解决在实验中难以完全跟踪原子沉积和薄膜生长物理过程的难题提供了途径,而成为搭建理论与实际应用的桥梁,对寻找合成有特殊性能的薄膜材料的实验技术及手段具有十分重要的指导意义。元胞自动机方法是根据微观个体的简单局域自组织相互作用机制来描述宏观系统整体复杂行为及其时间演化的“自下而上”的计算机模拟方法。本文针对薄膜生长过程粒子迁移扩散的复杂性,在分析薄膜生长过程及生长模式的基础上,结合蒙特卡诺方法,建立薄膜材料的三维元胞自动机生长模型。该模型通过元胞及其领域状态在按薄膜生长过程特征抽象得到的元胞自动机模型的局域自组织作用规则下的并行演化过程,利用OpenGL技术,在VC7.0环境下编程实现了对薄膜生长过程的直观模拟。通过对薄膜生长过程的计算机模拟,研究了薄膜生长过程中沉积速率和沉积温度等对薄膜表面形貌的影响以及薄膜生长过程三维分维数随覆盖率的变化情况。研究结果表明:在相同温度下较低的沉积速率范围内,薄膜粗糙度几乎不随沉积速率发生变化;随着沉积速率的逐步升高,薄膜粗糙度将逐渐增大;在相同沉积速率时,薄膜粗糙度随沉积温度的升高达到一个最小值,之后粗糙度又将随温度升高而增加,这说明并非沉积温度越高薄膜粗糙度越低;通过对薄膜生长过程三维分维数的计算,表面三维分形维数能够反映薄膜整体的自相似情况。模拟结果与实际情况相符,说明建立的模型是正确的,可以用于薄膜材料生长过程的模拟研究。更多还原

【Abstract】 The development of thin film materials has important effects in high-tech field such as microelectronics and MEMS. A considerable number of experimental and theoretical studies are focused on film growth,because many properties of thin film materials depend on the film morphology and microstructure which is influenced by the atom-level growing process. Use of computer simulation, dynamic process of atom-level thin film growth can be obtained, experiment phenomenon can be made clear and influence of experiment condition can be analyzed. It provides a way to find out the whole physical process of particle deposition and thin film growth. Because of these, it builds a bridge between theory and application and has important instructional meaning for finding experiment technology and means for obtaining thin film with special performance.Cellular automata model is a kind of computational model which can describe macroscopic complex behavior and its“bottom-up”evolution in a system which based on simple microscopic local interaction mechanism and self-organization evolutionary rules of components in the system. This paper aims at the complexity of migration and diffusion of particles. After analyzing the process and mode of thin film growth, a simulation model of thin film growth based on 3D Cellular Automata combine with Monte Carlo was built. The model based on cell and its neighbor and the local self-organization rules of cellular automata abstracted from the characteristic of thin film growth, use of OpenGL technology to achieved intuitive simulation of film growth process in the programming environment VC7.0.In this paper, through computer simulation of film growth, the effect of the deposition rate and deposition temperature on the surface morphology of film was investigated with the model, and the relationship between 3-D fractal dimension and covering rate was studied too. The relationship between roughness and covering rate for film under different conditions and relationship between 3-D fractal dimension and covering rate are discussed in detail in this dissertation. The results demonstrated that at the same deposition temperature, when the deposition rate is low, the roughness of film does not change with the increasing of deposition rate. However, the roughness of film rises with the increasing the deposition rate further. Especially, if they have the same deposition rate, the roughness of film will reach a minimum value and then increase with the increasing of deposition temperature. Therefore, it can be concluded that the roughness of film does not rise with the increasing of deposition rate. The 3-D fractal dimension calculated can reflect the whole self-similarity of thin film. Result of the Simulation is in line with the real situation and shows that the model built is correct and can be used to simulate the process of thin film growth.更多还原