Improvement on the reliability of flash EEPROM by annealing after self-aligned source dry etching

This paper describes the effect of annealing on the characteristics of cycl ing endurance and charge retention in flash electronically erasable program mable read-only memory (EEPROM) fabricated by self-aligned source (SAS! dry etching process which was used for the shrinkage of cell size. The anneali ng process was used for the recovery and thickness compensation of the tunn el oxide edge at which severe plasma damage was accumulated during the SAS dry etching process. Through the analysis of cycling endurance, it was clar ified that charge traps and structural defects were generated at the tunnel oxide edge during the SAS dry etching process and they induced the degrada tion of cycling endurance of memory cells. The characteristics of charge re tention were improved due to the structural recovery and the thickness comp ensation of the tunnel oxide edge. An analysis of the results from the meas urement of charge retention and the examination of the tunnel oxide edge wi th high resolution transmission electron microscope, indicates that the thi ckness compensation of the tunnel oxide edge affected more positively the r eduction of tail bits than the structural recovery of the tunnel oxide edge . (C) 2001 The Electrochemical Society.