High-resolution focused ion beam lithography

Abstract

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 1.0×1012 ions/cm2 dose 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.