Oxide thickness dependence of plasma charging damage

Charging damage induced in oxides with thickness ranging from 8.7 to 2.5 nm is investigated. Results of charge-to-breakdown (Q(bd)) measurements perfo rmed on control devices indicate that the polarity dependence increases wit h decreasing oxide thickness at both room and elevated temperature (180 deg rees C) conditions. As the oxide thickness is thinned down below 3nm, the Q (bd) becomes very sensitive to the stressing current density and temperatur e. Experimental results show that severe antenna effect would occur during plasma ashing treatment in devices with gate oxides as thin as 2.6 nm. It i s concluded that high stressing current level, negative plasma charging, an d high process temperature are key factors responsible for the damage. (C) 1999 Elsevier Science Ltd. All rights reserved.