Experimental Extraction of the Charge Centroid and of the Charge Type in the P/E Operation of Sonos Memory Cells

In this work, we report experiments on SONOS memory cells aimed to investigate the vertical position and the nature of the charge trapped in the gate stack during Program/Erase (P/E) cycling. To this purpose a new experimental setup has been developed to accurately detect the amount of injected charge and the consequent threshold voltage shift. The results, confirmed by different measurement techniques, show that the position of the charge centroid during program and erase operation is quite insensitive to the injection conditions. Moreover, we investigate by means of carrier separation experiments the role of the different type of carriers during program and erase operation of SONOS cells.