First-Principles Calculations of Energy Levels in Metal-Doped Silicon Nitride for Charge Trap Memory Applications

摘要

Introduction Silicon nitride-based three-dimensional (3D) NAND flash memory has become one of the rapidly evolving technologies in semiconductor memories [1]. The recent development of multi-level cell technology in NAND flash memory has offered a high-bit density and reduced cost per bit. However, this technology demands a large threshold voltage shift, which basically depends upon the amount of charge stored by deep trap levels distributed in silicon nitride. Thus, the introduction of point defects capable of inducing deep trap levels in silicon nitride is needed to realize high-bit density flash memories. In the present work, we investigate the energy levels caused by metal defects (Mg, Ti, Hf, V, Mn, and Al) in silicon nitride using first-principles calculations.