SURFACE IMAGING OF FOCUSED ION-BEAM EXPOSED RESISTS

Silylation processes have previously been applied to optical lithography to overcome deleterious substrate effects and to achieve smaller linewidths. We have applied silylation to focused ion-beam (FIB) lithography, thereby eliminating the need for exposure throughout the entire resist thickness. This approach permits the use of Ga+ ions which have a limited range in the resist but are available from high brightness sources. Thus FIB lithography writing speed can be dramatically improved. Sensitivity of 8 x 10(11) ions/cm2 was found with 30-keV Ga+ using SAL 601 resist, and linewidths below 100 nm have been demonstrated.