END-POINT DETECTION USING ABSORBED CURRENT, SECONDARY-ELECTRON, AND SECONDARY ION SIGNALS DURING MILLING OF MULTILAYER STRUCTURES BY FOCUSED ION-BEAM

Many applications of focused ion beam micromachining of multilayer str uctures require the ability to accurately and unambiguously signal the transition from one layer to the next during milling. Instances where this may be critical include most microcircuit sectioning, reconfigur ing, or repair operations. Here we compare absorbed specimen current w ith secondary electron and secondary ion signals and contrast their ef fectiveness in providing an indication of end-point. A number of thin film and multilayer samples have been investigated including thin film s of Au and W (thickness 0.1 mum) deposited on Si, and Al (thickness 1 .0 mum) deposited on thermally grown SiO2 (thickness 1.0 mum) on Si.