二级透镜聚焦离子束系统及其对中方法

介绍了一台使用液态金属离子源的二级透镜亚微米聚焦离子束系统。系统使用了可以微动的针尖以及电可调现场可变束径束流技术，在加速电压为１５ｋｅＶ，束流为３０ｐＡ时，束径可达到１００ｎｍ。在系统设计时，提出了逐级可测性原则，并在设计结构时同时设计一套科学的调整方案，使二级透镜系统的对中调整更加迅速可靠。探讨了一种新的对中判断方法，称为漂移法，就是在保证光阑孔和透镜光轴合轴很好的情况下，聚焦电压偏移一定量时像点位置的漂移最小时物点离轴最近。漂移法比常用的束径最小法更加灵敏、可靠。

Two lens FIB system and its method of alignment

A sub micron focused ion beam (FIB) system with Ga + liquid metal ion source (LMIS) and two lenses is described. In that system, an adjustable tip and the variable beam size and current technique were used. 100 nm beam size was achieved at 15 keV energy and 30 pA beam current. To overcome the difficulty of alignment in the two lens system, a successively testable principle was adopted, and a reasonable adjustment program was designed at the time of structure design. A more sensitive method for evaluation of alignment called drift method is discussed, which is based on the principle that the image drift caused by focus voltage variation will be minimized when the object is closed mostly to the axis of the lens.