The variability due to random discrete dopant and grain boundary in 3D NAND unit cell

We investigate the electrical variability of polysilicon (poly-Si) channels with the single discrete dopant (SDD) and single grain boundary (SGB) for 3D NAND applications. A 3D simulation is used to investigate the effect of the SGB and the SDD on the threshold voltage (Vth) and subthreshold swing (S/S) variation where the SDD and SGB are randomly located in poly-Si channels. The SGB affects the entire channel potential and causes the Vth and S/S variations. On the other hand, the SDD can cause only small fluctuation in the S/S characteristics.