扫描式氩离子枪的电子光学系统研究

Study on Electron Optical System of Scanning Ar Ion Gun

扫描式离子枪是样品表面清洁、表面刻蚀和深度分析的常用部件,加速电压在500V到3kV之间可调,具有效率高、性能可靠等优点。电子光学系统是离子枪的重要组成部分,是决定离子束流品质的重要因素。本文利用计算机模拟软件CST对离子枪整体结构进行建模,研究了离子枪聚焦系统不同结构和电压参数对离子束电流密度和束斑尺寸的影响,同时得到了离子枪偏转系统在不同电压分布下的离子分布情况,通过仿真分析确定了电子光学系统的设计方案,并进行了实验验证。结果表明:工作距离为25mm、氩气工作气压为6×10-3Pa、加速电压为3kV时,氩离子束的束流大小为3μA;束斑大小在7mm到12mm之间可调;当偏转电压为300V时,偏转角度为4.6°。实验与仿真结果基本对应,同时该离子枪的性能指标可获得表面原子精度构造。

Scanning ion gun is a common component for sample surface cleaning,surface etching and deep analysis, the acceleration voltage of which can be adjusted from 500V to 3kV. It has the advantages of high efficiency and reliable performance. Electron optical system is an important part of ion gun and an important parameter to determine the ion beam quality. In this paper, the computer simulation software CST is used to model the overall structure of the ion gun, the effects of different structure and voltage parameters of the ion gun focusing system on the ion beam current density and beam spot size are studied, and the ion distribution of ion gun deflection system under different voltage distribution is obtained. The design scheme of the electronic optical system is determined by simulation analysis and is verified by experiments. The test results show that when the working distance is 25mm, the working pressure of argon gas is 6×10-3Pa and the acceleration voltage is 3kV, the argon ion beam size is 3μA. Beam spot size can be adjustable from 7mm to 12mm. The deflection angle is 4.6° when deflection voltage is 300V. The test results are basically consistent with the simulation results, and the surface atomic precision structure can be achieved by the performance index of the ion gun.