Microcolumn based low energy e-beam writing

Abstract

In this paper first results on electron beam lithography with a microcolumn are presented. Our miniaturized e-beam writer is designed to explore the energy range below 1 keV. This range is attractive because the mean free path of the electrons has a minimum at approximately 100 eV. It is expected that resists are extremely sensitive at these energies and that proximity effects are highly reduced. Both effects could help to accelerate the lithography process or to allow the exploration of new processes. Test exposures were made on spin-coated, 50-nm-thick films of PMMA, hydrogen-passivated silicon and self-assembled monolayers on gold-coated silicon. The patterns were analyzed by means of optical, atomic force and scanning electron microscopy where appropriate, as well as with a profilometer. As expected, the depth of the profiles in PMMA were very shallow. Typical values lay between 2 and 7 nm for energies between 100 and 200 eV.