Impact of Pulsed Operation on Performance and Reliability of Flash Memories

We tested the impact of pulsed operation (PO) on standard NOR flash memory arrays. PO is a new writing scheme featuring a sequence of ultrashort high-voltage pulses based on Fowler-Nordheim (FN) tunneling. This paper presents experimental results showing a significant improvement on both performance and reliability of Flash memory arrays using PO which include smaller standard deviation of the threshold-voltage distribution, less tail bits, and less cycling-induced tunnel oxide degradation. Measurements reveal also that a specific array design taking into account for both wordline and substrate parasitic capacitances can further increase the benefits deriving from the use of PO. The proposed PO writing scheme is suitable for all floating gate memories using FN tunneling as writing mechanism.