Abstract: 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.

Key words: ion gun, electron optical system, electrostatic focusing, electrostatic deflection