ELECTRON-BEAM EXPOSURE PROFILES IN POLYMER-FILMS FOR METALLIC FILM MASK FABRICATION

The effect of the metallic thin film on energy dissipation profiles in a resist polymer film on a metallic film-clad glass plate as in mask fabrication was investigated experimentally and by Monte Carlo calculations which take an exact account of the above boundary condition for a specific geometry. The thicknesses of the polymer film and metallic films are 8000 A and 500-800 A, respectively. Various metals such as Al, Cr, Mo, and Ta are used as mask materials. Both experimental and theoretical results show that the width of the developed profile increases with an increasing atomic number of the metallic film element depending on exposure density as expected due to increasing backscattering from the metallic film. It is concluded that even a very thin metallic film has an appreciable effect on the profile and its effect is exaggerated either by a large dose or by a strong development.