TCAD Investigation of Abnormal Degradation of Inhibited Cells in NAND Flash Structures

In this paper, we propose to investigate the abnormal degradation on inhibited cells in NAND structures when cycling the addressed cell. The impact of the electric field is first explored and shows that the electric field isn\´t the main source of degradation. Then we try to identify the phenomenon occurring in the inhibition phase called "channel boosting". To visualize the potential in the channel area, a 2D TCAD simulation, emulating a 3D behavior by taking into account parasitic capacitances in the array, is developed and calibrated. We succeed in reproducing the bias conditions in the inhibited cell and to observe the emergence of a source/drain bias during the rising of potentials.