Simulation of space charge neutralization using ions in electron beam projection optics

We have investigated, using Monte Carlo simulations, space charge neutraliz ation using ions in a 4:1 telecentric doublet electron beam (e-beam) projec tion optics. The simulations were performed for two extreme conditions; one with ions moving at the same axial velocity as the e-beam, the other with stationary ions. For both conditions, global space charge effects; defocus, field curvature and magnification change are almost completely eliminated. Although the stochastic coulomb interaction is increased the total point s pread which determines resolution can be decreased, because of the eliminat ion of space charge induced spherical aberration. This suggests that space charge neutralization can reduce the global space charge effects without in ducing unacceptable stochastic effects. (C) 2001 Elsevier Science B.V. All rights reserved.