New insights into the charge loss components in a SONOS flash memory cell before and after long term cycling
In this paper, the ONO layer scaling effect and the leakage components in a SONOS cell have been extensively studied. The reliability with focus on both endurance and data retention has been demonstrated. Results show that thinner blocking oxide has better endurance, while it has poorer data retention. For the data retention before cycling, thermionic and direct tunneling, in relation to the data loss, are the two dominant leakage components, which can be separated. Moreover, after cycling, we have been able to separate a third component - the trap-to-trap tunneling current. These results are useful toward an understanding of the leakage mechanisms of SONOS cell as well as the scaling effect of ONO layers.