基于几何相位分析的Nb-Si{001}界面应变研究

Strain Study of Nb-Si{001} Interface Based on Geometric Phase Analysis

用高分辨电子显微成像和几何相位分析,研究不同溅射气压下制备的铌薄膜/硅基体的界面微观结构和应变状态。结果表明:铌薄膜表面由花瓣状层片组织构成,层片组织随机分布,没有明显的特征取向;随着溅射气压的增大,层片尺寸随之增大,致密度减小,出现大量孔隙,铌薄膜和硅基体之间存在铌、硅元素的混合层;当溅射气压为0.65 Pa,0.85 Pa和1 Pa时,硅基体中应变ε_(xx)分别是–0.16%,–0.30%和0.42%,ε_(yy)分别是–1.23%,–0.31%和0.26%,溅射气压对硅基体的应变状态具有很大影响;硅基体的应变主要来自于界面混合层和铌薄膜的作用,混合层中铌原子和硅原子相互混杂,存在大量结构缺陷,产生本征应力,从而导致硅基体中产生应变。

High resolution electron microscopy imaging and geometric phase analysis were employed to study the microstructure and strain states of Nb/Si interface prepared at different sputtering pressures.The results show that the surface of Nb thin film consists of petals-shape lamellas with random morphological distribution and no obvious characteristic orientation.The size of the lamella increases and the density of the lamella decreases with the increase of deposition pressure meanwhile,a large number of pores appear on the surface of Nb film and a mixed layer of Nb and Si is generated between Nb film and Si substrate.When Nb films were deposited at 0.65,0.85 Pa and 1 Pa,the strain values ofεxx were respectively–0.16%,–0.30%and 0.42%;the strain values ofεyy were respectively–1.23%,–0.31%and 0.26%.The strain states of Si substrate are tremendously influenced by the disposition pressure.The strain states of Si substrate are mainly produced by the effect of the interfacial mixed layer and Nb thin film.A large number of structure defects are generated in the mixed layer of Nb and Si,which produces intrinsic stress in the mixed layer,and further results in the formation of strain in Si substrate.