Electron beam projection lithography system (EBPS)

摘要

Numerous largely unpredictable criticalities of operating parameters arise in electron beam projection lithography systems to maintain throughput comparable to optical projection lithography systems as minimum feature size is reduced below one-half micron and resolution requirements are increased. Using an electron beam projection lithography system having a high emittance electron source, variable axis lenses, curvilinear beam trajectory and constant reticle and/or target motion in a dual scanning mode wherein the target and/or wafer is constantly moved orthogonally to the direction of beam scan, high throughput is obtained consistent with 0.1 mu m feature size ground rules utilizing a column length of greater than 400 mm, a beam current of between about 4 and 35 mu A, a beam energy of between about 75 and 175 kV, a sub-field size between about 0.1 and 0.5 mm at the target at an optical reduction factor between about 3:1 and 5:1, a numerical aperture greater than 2 mrad and preferably between about 3 and 8 mrad and a scan length between about 20 mm and 55 mm. Reticle and target speed preferably differ by about the optical reduction factor.