Low Energy Electron Beam Lithography

The use of low energy electron beams (<5 keV) to expose polymeric resists has been limited due to worse aberrations, lower available current density, and the difficulties involved in spinning on a very thin continuous resist layer. The first two problems can be eliminated by applying a retarding electric field directly above the workpiece. Computer simulations showing space charge effects on the probe size and improved aberrations coefficients are presented. An inorganic resist, GeSex, is ideally suited for this lithography due to the very shallow active layer ~0.01 um. Experimental results showing the favorable effects due to lower electron landing energy on the required dose and proximity effects are also presented. Lateral scattering in the resist is simulated by Monte Carlo techniques for 2 and 20 keV isolated, unexposed, submicron lines.