The effect of Coulomb interaction in a variable shaped e-beam (EB) lithography system was studied. The effect of Coulomb interaction was estimated by a simulation. The simulation results predicted that beam blur due to Coulomb interaction in a variable shaped EB lithography system operated at the beam current density as high as 10 A/cm(2) was not negligible for measurement and correction of beam size based on beam profile measurement, which deteriorates beam size accuracy by several hundredth micron. A new beam size correction method free from the effect of Coulomb interaction, which was based on beam current measurement, was implemented. The beam size accuracy of the new correction method was compared to that of conventional one, experimentally. While beam size errors exceeding 35 nm were found with the conventional correction method based on beam profile measurement, beam size errors were less than 10 nm with the new correction method based on beam current measurement. A beam size correction method based on beam current measurement is indispensable for a variable shaped EB lithography system operated at high current density in order to avoid the effect of Coulomb interactions and to attain high CD accuracy.