Study of Intra-Nitride Charge Transport of SONOS-Type Devices using Gate-Sensing and Channel-Sensing Transient Analysis Method

For the first time we can directly investigate the charge transport and intra-nitride behavior of SONOS-type devices. Using the recently developed gate-sensing and channel-sensing transient analysis method, the injected charge density (Q) and charge centroid (x) can be accurately measured. Our results clearly indicate that for electron injection (+FN programming), the electron centroid migrates from the bottom toward nitride center, while for hole injection (-FN erasing), holes first compensate for the bottom electrons and then gradually populate the upper portion. For the electron de-trapping processes under -Y_G stressing, the trapped electrons also de-trap first from the bottom portion of the nitride. During short-term high-temperature baking, the electrons move from the top portion toward the bottom portion, and this intra-nitride transport become more significant for a thicker nitride. On the other hand, after long-term baking, the charge loss mainly comes from the bottom portion of the nitride.