Computer modeling of charging induced electron beam deflection in electron beam lithography

The charging of the workpiece in electron beam direct writing processes has been identified as a problem that disturbs the electron beam aid causes pattern displacement error. In this paper the electron beam deflection caused by surface charging is evaluated by the SIMION and MATHEMATICA simulation programs. Isolated charged patterns of different geometry are simulated as electrodes with given potentials in SIMION to calculate the extent of beam deflection, while secondary electron emission yield and beam dosage are assigned in MATHEMATICA programming for determination of surface potential and spatial field, from which the beam deflection is then calculated The simulation results are in good agreement with each other and they are compared with values available in literature. The initial charge content along with the pattern dimensions chosen in simulation are found to be the major factors that determine the extent of beam deflection. The limitation of SIMION simulation on the beam deflection is also discussed.