Recovery of shifted MOS parameters induced by focused ion beam exposure

The effects of focused ion beam exposure on MOS transistors within a circuit were examined. It was found that FIB exposure does not cause parameter shifts as long as the gate is connected to p-n junctions of other transistors. On the other hand, the threshold voltage (Vt) does shift during isolating the gate using a FIB. Further FIB exposure on MOS transistors with a floating gate is shown to cause larger shifts. We demonstrated that a 400 - 450 °C anneal could recover shifted Vt almost completely.