Electrical degradation and recovery of dielectrics in n++-poly-Si/SiOx/SiO2/p-sub structures designed for application in low-voltage non-volatile memories

In this paper we Study the degradation and recovery of dielectrics in n(++)-poly-Si/SiOx/SiO2/p-sub capacitors designed for application in low-voltage flash EEPROM memories. Constant current stress experiment have been performed and the gate voltage in the Fowler-Nordheim (FN) regime and the flat-band voltage monitored. Experiment demonstrated that SiOx has a greater tendency to trap electrons than pure SiO2 and exhibits a larger voltage shift in the FN regime after electrical stress. On the other hand, permanent recovery of the leakage current can be obtained by injection of current at very low flux. This effect has been tentatively explained with the annealing of native metastable defects occurring in concurrence with the stress induced creation of new traps, (C) 2001 Elsevier Science Ltd. All rights reserved.