Impact of Poly-Si channel: Multiscale modeling insight from first-principles to device simulation

In the age of big data and the tremendous pace of data generation, there is a strong demand for ultra-high density storage devices. One of the frontrunners in the current workhorse is NAND flash memory devices. 3D integration and stackability is the key to the increase in storage density which enabled the wearable revolution. Despite becoming the mainstream and being inside every PC and mobile phone their operation and future are impacted by the constraints of a poly-Si channel. Poly-Si materials are characterized by the presence of several defects like voids, grain boundaries (GBs), etc. GBs can exert a detrimental influence on electrical performance and its variability. However, the electrical activity of GBs strongly depends on the orientation of grains (barrier impacting electron scattering). In this work, the impact of GBs on the poly-Si channel is investigated in a charge-trap 3D NAND flash memory. Statistical distributions of

ON current, threshold voltage, and sub-threshold slope are extracted with random grain distributions using the Ginestra® modeling platform, where fundamental properties of GBs, with and without different impurities are taken from density functional theory (DFT). The results provide insights to examine the factors affecting the electrical activity of GBs and their impact on electron scattering. Knowledge of optimal parameters from DFT and its use on modeling devices could be an effective way to mitigate the sensing instability and improve the device's performance.