The resolution and alignment accuracy of FIB lithography is studied for making devices with 0.1 μm dimensions. 0.1‐μm linewidth patterns are successfully fabricated by 260‐keV Be++FIB for both positive and negative resists. 50‐nm linewidth Novolak based negative resist patterns are fabricated at 1.0×1012ions/cm2dose by 260‐keV Be++ FIB. Dot patterns with 0.3 μm diam and high density (108/cm2) are written on a 1×1 cm area in a PMMA resist to demonstrate that FIB lithography can be applied to make practical devices with a large writing area. Moreover, mark detection and overlay accuracy are studied for marks covered with PMMA and CMS resists. Finally, FIB lithography is applied to fabricate 0.1‐μm NMOS gate patterns. The overlay accuracy for hybrid exposure using FIB and an optical stepper is 0.2 μm at 2σ.