The Effects of Program/Erase Cycles on the ONO Stack Layer in SONOS Flash Memory Cell Investigated by a Variable-Amplitude Low-Frequency Charge-Pumping Technique

In this paper, influences of program/erase (P/E) cycles on the defect generation in a SONOS flash memory cell are studied by using a variable-amplitude low-frequency charge-pumping technique. We observe that P/E cycles would generate new oxide and nitride traps, and degraded cell retention is observed. Besides, the increase of oxide- and nitride-trap densities follows a power-law behavior as a function of P/E cycles. We also observe that these stress-created oxide and nitride traps are unstable and will be eliminated rapidly during high-temperature storage.