Limitations of rapid thermal processing on ultra-shallow junctions for sub-0.25 mu m MOSFETs

Very shallow ( approximately 0.1 mu m) junctions are needed for sub-0.25 mu m MOSFET devices. These junctions can be made by implanting dopants into silicides and then drive out by RTA. Compared to furnace processed junctions, however, the RTA processed junctions show a higher leakage current, coupled with a non-ideal diode behavior. In addition, good junctions processed by furnace annealing showing ideal behavior and low leakage current are converted to leakier non-ideal diodes after an additional RTA. On the other hand, leaky junctions processed by RTA can be 'cured' by an additional furnace annealing. The authors conclude that Rapid Thermal Processing has to be carefully engineered to produce useful shallow junctions for 0.25 mu m and sub-0.25 mu m devices.<<ETX>>