M. Cheng et Tt. Tang, Demagnifying immersion magnetic lenses used for projection electron beam lithography without crossovers, J VAC SCI B, 18(6), 2000, pp. 3132-3137
Curvilinear-axis electron optical focusing and aberration theory of wide el
ectron beams in immersion magnetic lenses, which can be used for projection
electron beam lithography, are put forward, and second-order aberration fo
rmulas have been derived using the symbolic manipulation software MATHEMATI
CA(R). A program was written to calculate numerically the wide beam Gaussia
n focusing and aberration properties of these lenses by using the curviline
ar-axis theory. The magnetic structures that have convergent force lines ha
ve been studied. As an example, lenses with an analytical axial magnetic fi
eld distribution are calculated. The results show that wide beam projection
images without crossovers can be formed with demagnified lateral magnifica
tion, and with a submicron and nanometer lateral resolution over a larger f
ield size. (C) 2000 American Vacuum Society. [S0734-211X(00)07006-2].