亚微米聚焦离子束的漂移现象

研究了亚微米聚焦离子束（FIB）系统的漂移现象，给出了测量漂移的方法，分析引起漂移的原因及降低漂移的措施。发现了偏转电极上钝化层及污染物充电电荷所引起的漂移现象；测出了各电极电压变化所引起漂移的大小；发现了由于外壳温度不均匀引起离子枪轴线相对样品变化所引起的漂移。提出了制作透镜电极时保持轴对称、特别是限制光栏必须位于透镜光轴上的必要性。所给出的漂移数据既包含早期曾研制的单级透镜FIB系统的数据，也包含近期研制的二级透镜可变束流FIB系统的数据。

The Beam Drift in the Sub-micron Focused Ion Beam System

In this paper,the beam drift phenomenon in the sub-micron focused ion beam(FIB)system we built have studied. The scheme of drift measurement is shown,and the factors causing the drift and the methods to reduce the drift are discussed. We have discovered the drift phenomenon due to the charges on the oxide or contaminant deposited on the surfaces of the deflection electrodes. We measured the drift dueto the voltage variation of the electrode in the lens. We discovered the drift due to the direction change of the lens axis versus the specimen because of the themal unevenness of the shell. The necessity of the lens electrode coaxality especially the coaxality of the aperture with lens axis is emphasized. The data shown in the paper include not only that of the single-lens system we built previously,but also that of the variable beam current two-lens system we built recently.