薄膜表面形貌的相场方法模拟

PHASE FIELD SIMULATION ON THIN FILM SURFACE MORPHOLOGY

在半导体以及光电设备中,在衬底上生长的高质量薄膜引起了广泛的兴趣,薄膜的生长以及薄膜的表面质量对薄膜的性质有巨大的影响。由于薄膜和衬底之间广泛存在着错配应变,以至于薄膜生长超过一定临界厚度后,不可避免地引入位错,使得薄膜的表面粗糙度增加,降低薄膜质量。如何预测与描述薄膜的表面,通过控制生长方式以及生长速度降低表面粗糙度成为生长高质量最为关注的问题。近年来,由于相场方法可以避免追踪界面,并通过引入包含错配应变效应的弹性能进入热力学自由能计算,使得相场方法在研究模拟薄膜表面形貌特征方面有了广泛的应用。论文首先简单地介绍了薄膜生长的几种主要模式,临界厚度以及薄膜表面的不稳定性问题,随后重点介绍了近十余年来相场方法在计算薄膜表面问题,薄膜生长问题方面开发出来的一系列研究手段与研究成果,最后总结与展望,为未来相场方法在该领域的工作提供理论方向。

High quality thin film growth on a certain substrate has attracted great interest in semiconductors and optical-electric devices.Growth modes and surface quality of thin films have a strong influence on the thin film properties.Due to the misfit strain between the thin film and its substrate,dislocations are inevitably introduced when the growth of thin films exceeds a certain critical thickness,which can increase the surface roughness of thin films and reduce the quality of thin films.How to predict and describe the surface morphology,and how to reduce surface roughness by controlling the growth mode and growth rate have become the most concerned topics in high quality thin film growth.Recently,phase field method has many applications on the surface morphology prediction due to its advantages on avoiding tracing interfaces and introducing the elastic energy of mismatch strain effect into the calculation of thermodynamic free energy.This paper firstly introduces the thin film growth modes,critical thickness and the instability problems of thin film surface.Secondly,we present some research works on the phase field simulation on the thin film growth and the surface morphology in the last decades,including simulation methods and research results.Finally,we give a summary and prospect to provide the potential opportunities for phase field model in this research field.