Accelerated Program Inhibition Failure by Trap-Mediated Tunneling in the Polycrystalline Floating-Channel 3-D NAND Flash Memory Array

In this work, we have investigated the effects of trap-mediated tunneling on program inhibition in the 3-D NAND flash memory. By a series of rigorous array-level TCAD simulations, it has been found that the self-boosted channel in the unselected bitline experiences a potential drop by direct inter-band tunneling, which can be significantly accelerated by trap-mediated tunneling. It is judged both types of tunneling events are inevitable and proper methods to lessen them need to be sought since the body biasing cannot be controlled and the bitline channel is made of poly-Si having abundant trap sites in the current 3-D NAND flash memory technology.