HIGH-RESOLUTION FOCUSED ION-BEAM LITHOGRAPHY

The resolution and alignment accuracy of FIB lithography is studied for making devices with 0.1-mu-m dimensions. 0.1-mu-m 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 x 10(12) ions/cm2 dose by 260-keV Be++ FIB. Dot patterns with 0.3-mu-m diam and high density (10(8)/cm2) are written on a 1 x 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-mu-m NMOS gate patterns. The overlay accuracy for hybrid exposure using FIB and an optical stepper is 0.2-mu-m at 2-sigma.