A Novel Gate-Sensing and Channel-Sensing Transient Analysis Method for Real-Time Monitoring of Charge Vertical Location in Sonos-Type Devices and its Applications in Reliability Studies

By using poly-gate-sensing in addition to the conventional channel-sensing for Vt (or VFB) presents a novel transient analysis method that is very powerful to monitor the trapped charge vertical location in real time. The sensing in both modes provides two equations that are suitable to solve for two variables - the charge density (Q) and the average charge vertical location (x). Without the second equation (from poly-gate-sensing) Q and x cannot be de-convoluted. The power of this new technique is demonstrated by several examples of reliability studies for SONOS-type devices. The charge trapping efficiency of silicon nitride of different thickness is examined. The charge migration during program/erase cycling and data retention information is observed for the first time using this new tool. The method presented in this work is indeed a powerful tool for detailed understanding of trapping dynamics.