Salicided source/drain considerations on UTF SIMOX

Integration of the salicide process with ultrathin film (UFT) SOI (silicon-on-insulator) requires consideration of concerns relating to the limited amount of silicon in the source/drain regions. With improper source/drain doping strategies a resistive Schottky diode characteristic may result, providing severely limited gate drive. This effect can be modeled in PISCES-2B. Comparisons between hardware and simulation on salicided and nonsalicided devices are presented along with a variety of source/drain designs intended to avoid the formation of this device series resistance component. Analysis of the simulations indicated that the series resistance is caused by current crowding at the source edge, since the Schottky diode is reverse-biased and unable to participate in electron injection. This problem becomes more severe at reduced silicon thicknesses