Generation and applications of finely focused beams of low-energy electrons

In electron-beam lithography, two well-known problems are proximity effects due to electron scattering and slow throughput because of limited exposure rate and resist sensitivity. We have investigated the generation of finely focused electron beams of low landing energy (?5 keV) and their application to materials processing. Lenses employing magnetic and retarding electric fields are found to have very low spherical and chromatic aberrations, thus facilitating the production of beams of low-energy electrons without seriously sacrificing current density. With such beams the power dissipated per unit volume at the surface of a bulk target is higher than with high-energy electrons, thus increasing the speed to exposure of very thin resists and dramatically reducing proximity effects. This compact volume of high-power dissipation is also attractive for selected area annealing.