0.2μm聚焦离子束系统中电源稳定度的研究

Research of voltage's stability in 0.2μm focused ion beam system

为了在所研制的二级透镜聚焦离子束系统中获得直径小于０．２μｍ的稳定束斑，并进行亚微米微细加工，分析了影响束斑大小及稳定性的因素，并着重从像差、散焦和漂移的角度，利用理论分析和模拟计算，研究了决定系统光学性能的离子源、离子引出极、预聚焦极、聚焦极所用高压电源及电对中、消像散透镜、偏转器所用低压电源的稳定度对离子束径的影响，得到了束直径小于０．２μｍ时电源必须达到的稳定度，即高压电源的纹波系数１×１０－４～１×１０－５，低压电源的纹波系数６×１０－４～１×１０－４。

In order to produce an ion beam diameter smaller than 0.2μm in our two lens FIB system and to perform microfabrication stably, we analyzed the factors which influence the size and stability of ion beam. More particularly, from aspects of aberration, misfocussing and drifting, with theory calculation and computer simulation, we researched the fluctuations of ion beam diameter caused by high voltage powers including ion energy voltage, extractor voltage and focusing voltage, which control the optical column characteristics, and low voltage powers including alignment voltage, astigmator voltage and deflector voltage. The results indicate that when the beam diameter is smaller than 0.2μm, the fluctuation coefficient of the high voltages is 1×10 -4 ～1×10 -5 and that of the low voltages is 6×10 -4 ～1×10 -4 .