Anomalous positive charge trapping in thin nitrided oxides under high-field impulse stressing

Abstract

An anomalously high density of positive trapped charges was observed in thin (43 Å) nitrided gate oxides subjected to high-field impulse stressing. The hot-hole generation occurs via a regenerative feedback mechanism, with minimal charge relaxation due to the short duration of the impulse stress. This gives rise to an extremely high density of trapped holes that were not observed under direct current stressing conditions. The trapped holes can be easily annealed electrically at room temperature and the annihilation of positive trapped charges is accompanied by a higher number of interface states being created. A better understanding on thin oxide degradation under impulse stressing can help in the choice of a suitable programing/erasing pulse width/amplitude for use in endurance testing of nonvolatile memories. © 2000 American Institute of Physics.