Direct-Write Ion Beam Lithography

Table 3

Ion sources (list of LMIS sources from [7, 20, 22, 163]). The ion species listed as “available” are available from well-developed sources and are featured in commercial instruments.

Source type	General properties	Ion species
Liquid metal ion sources	Virtual source size 10–20 nm; Typical pattern res 10–20 nm; Typical beam currents up to a few nA for Ga and up to 10–100 pA for most other species; Very good long-term stability and lifetime for Ga, improving performance for well-known systems like AuSi and AuGe; Sputter yield mostly medium to large	Available: Ga, Au, Si, Ge; Also exist: Ag, Al, As, B, Be, Bi, C, Ce, Co, Cr, Cs, Cu, Dy, Er, Fe, Hg, In, K, Li, Mg, Mn, Na, Nb, Nd, Ni, P, Pb, Pd, Pr, Pt, Rb, Sb, Sm, Sn, U, Y, Zn
Gas field-ionization sources	Virtual source size below 2 nm (He, Ne); Typical pattern res 5–10 nm; Typical beam currents up to 10 pA; Limited stability and lifetime; Sputter yield mostly small to medium	Available: He, Ne; Also exist: H, Ar
Plasma sources	Virtual source size ~10 µm; Typical pattern res 100 nm–1 µm; Typical beam currents up to a few µA; Good stability; Sputter yield mostly medium to large	Available: Ar, Xe; Also exist: H, He, N, O