应用于纳米级聚焦离子束系统的静电透镜设计  

Design of electrostatic lenses in nanometer scale focusing ion beam system

作　　者：李文萍[1] 顾文琪[2] 

机构地区：[1]北京航天航空大学,北京100083 [2]中国科学院电工研究所,北京100080

出　　处：《光学精密工程》2007年第6期829-834,共6页Optics and Precision Engineering

基　　金：科技部科学仪器设备升级改造专项项目(No.2005JG100050)

摘　　要：在不同束流和能量下对离子光柱体进行了优化设计。给出了用阻尼最小二乘法设计的单个透镜和透镜系统,并研究了像平面处的离子束性能。采用先分解再组合的方法确定单个透镜参数,并以大束流、无限大放大倍数下像差系数与焦距的比为优化目标。选取工作模式时综合考虑了系统的光学性能和可实现性,大束流下采用平行模式,小束流下采用交叉模式,设计的透镜系统在大、小束流下分别选轴上像差和放大倍数为优化目标。计算表明,2 nA束流下像差为16.33 nm,放大倍数为-0.539 095 5,束斑直径为31.52 nm;2.5 pA束流下像差为2.15 nm,放大倍数为0.084 359 9,束斑直径为4.73 nm。此离子光柱体能够获得纳米量级的离子束,并且只需调整第二透镜第二、第三电极之间的距离以及第二电极电位(对源)就能改变样品处的束能,增加了光柱体的应用范围,实现了一套系统内同时具有刻蚀、沉积、注入和离子成像等功能。A new focusing system was designed by optimizing its optical properties in different beam currents and energies. Damped least square method was used to design a single lens and lens system. The single lens was designed through combination of separating and assembling, and the ratio of aberration coefficient and focus length at infinite magnification was chosen as the objective. Both optical properties and practicability were considered when choosing the working modes between lenses. Collimated mode was used in the larger beam current while crossover mode was in the smaller one. Axial aberration and magnification were the objective in bigger beam current and in the smaller one respectively when optimizing the two lenses. The results show that the resolution is 31.52 nm （the magnification is -0. 539 095 5 and the aberration is 16.33 nm） and 4.73 nm （the magnification is 0. 084 359 9 and the aberration is 2.15 nm） under beam current of 2 nA and 2.5 pA. The lens system can work under different beam energies when adjusting the potential on the second plane and the space between the second plane and the third plane of the lens 2, which will enlarge its applications, and the etching, deposition, implantation and imaging can be realized in the same system.

关 键 词：聚焦离子束 静电透镜 阻尼最小二乘法 工作模式 束流密度分布 

分 类 号：TN16[电子电信—物理电子学] TH703[机械工程—仪器科学与技术]