Charge diffusion in silicon nitrides: Scalability assessment of nitride based flash memory

Electron and hole diffusion coefficients of stoichiometric silicon nitride, silicon rich nitride, and silicon oxynitride were evaluated from variable temperature electrostatic force microscopy (EFM) analysis. Among them, stoichiometric silicon nitride is shown to have smallest diffusion coefficient although silicon oxynitride has the higher temperature activation energy. Scaling charge trap flash towards sub-20nm regime should be accompanied by hole dispersion management, minimization of internal electric field, and adjustment of retention specification.