Polycrystalline-Si TFT TANOS Flash Memory Cell With Si Nanocrystals for High Program/Erase Speed and Good Retention

This letter presents a polycrystalline-silicon channel TaN-Al₂O₃-Si₃N₄-SiO₂-silicon (TANOS) nonvolatile memory (NVM) with a charge-trapping layer of embedded Si nanocrystals (NCs) (Si-NCs). The fabrication process of the Si-NCs is simple and highly compatible with the current Flash process. NCs enhance the program/erase speed of the NVM devices because the interface between Si-NCs and nitride contains numerous trapping sites for storing electrons. Moreover, the Si-NCs locally concentrate the electric field and reduce the effective nitride thickness. The NC TANOS exhibits a charge loss of only 5% for ten years of data storage.