The kinetics of degradation of data retention of post-cycled NROM non-volatile memory products

The kinetics of degradation of the threshold voltage of post-cycled NROM products is investigated. The root cause of the threshold voltage drift is attributed to hole accumulation over the junction edge during cycling. During retention bake, the excess holes migrate laterally in the nitride layer to annihilate electrons trapped over the channel. Comparison of the kinetics of the threshold voltage drift and the transport kinetics of silicon dioxide excludes vertical charge loss through the top or bottom oxide layers as an effective mechanism of data retention degradation in unbiased NROM products.