Analysis of HBM Failure in 3D NAND Flash Memory

Electrostatic discharge (ESD) events are the main factors impacting the reliability of NAND Flash memory. The behavior of human body model (HBM) failure and the corresponding physical mechanism of 3D NAND Flash memory are investigated in this paper. A catastrophic burn-out failure during HBM zapping is first presented. Analysis shows that NMOS fingers’ local heating induced by inhomogeneous substrate resistance Rsub and local heating induced by the drain contact and 3D stacked IC (SIC) structure lead to the failure. Therefore, a new approach is proposed to reduce local heat generation. Finally, by increasing N+ length (NPL) and introducing a novel contact strip, the silicon result shows enhanced ESD robustness.