A novel leakage current separation technique in a direct tunneling regime gate oxide SONOS memory cell

In this paper, data retention for various top and bottom oxide (tunnel oxide) SONOS cells has been extensively investigated. For the first time, a leakage current separation technique has been developed to distinguish the two leakage current components via thermionic and direct tunneling (DT) in the ONO layer. Results show that the short-term leakage is dominated by the direct tunneling, while the long-term leakage is dominated by the thermionic emission. The direct tunneling through either tunnel or blocking oxide can also be identified experimentally. These results are useful toward an understanding of the scaling of the SONOS cell with focus on its reliabilities.