COMPARISON OF FORMING GAS, NITROGEN, AND VACUUM ANNEAL EFFECTS ON X-RAY-IRRADIATED MOSFETS

The effects of radiation intensive lithography and three different ann eal treatments on nMOS hot-carrier vulnerability have been studied. Th e gate oxides of devices irradiated with X-rays after complete process ing and subjected to forming gas, nitrogen, and vacuum anneals were ch aracterized using photoinjection and channel hot-carrier stressing exp eriments. Photoinjection characterizations indicate that neutral as we ll as positively charged electron traps are present in the bulk oxide after the anneal treatments, with no discernible ambient dependence. C hannel hot carrier stressing over the full range of CMOS operating poi nts, however, indicates that the device treatments improve the stabili ty of the interface to varying degrees depending on the anneal ambient . The X-ray irradiated and nitrogen annealed devices were found to be least vulnerable to channel hot-carrier degradation.