Proximity Effects in Electron Beam Lithography.

Abstract : The required miniaturization of military IC devices to submicron and ultra-submicron dimensions in the 1980s raises serious questions regarding the use of electron beam (e-beam) lithographys an appropriate fabrication technique for this end. In this paper it is shown that the ultimate resolution of the e-beam process is determined by electron scattering effects in the lithographic resist material and by electron back-scattering from the underlying device substrate. The merit of the e-beam fabrication technique for use in very high speed integrated circuit (VHSIC) technology is assessed. A study is presented which describes the electron scattering and backscattering processes in electronic materials. A theoretical analysis describing primary electron backscattering from single- and double-layered substrates is presented; also, attention is focused on the question of the spatial region exposed by a scattered e-beam in a lithographic e-beam resist material. Experimental electron backscattering, e-beam, and scanning electron microscopy studies are used to corroborate theoretical findings. (Author)