SUPPRESSION OF HOT-CARRIER-INDUCED DEGRADATION IN N-MOSFETS AT LOW-TEMPERATURES BY N2O-NITRIDATION OF GATE OXIDE

Hot-carrier effects of N2O-nitrided (N2ON) n-MOSFE7s at low temperatur e are investigated under maximum substrate-and gate-current stresses, respectively. The results are compared to those of thermal-oxide (OX) n-MOSFETs. It is found that like the characteristics at room temperatu re, hot-carrier-induced degradations are greatly suppressed in N2ON de vices relative to OX devices under the two stresses, suggesting excell ent low-temperature hot-carrier reliability due to nitrogen incorporat ion at/near the Si-SiO2 interface. For an OX device at low temperature , maximum gate-current stress exerts a stronger influence on its trans conductance, threshold voltage and subthreshold swing than maximum sub strate-current stress, and a two-piece model is used to explain the ph enomena. Moreover, less shallow-trap generation observed in the N2ON d evice than in the OX device at low temperature is also attributed to t he role of N2O nitridation. (C) 1998 Published by Elsevier Science Ltd . All rights reserved.