R&D: Microscopic Physical Origin of Charge Fraps in 3D NAND Flash Memories

The Japan Journal of Applied Physics has published an article written by Fugo Nanataki,Nagoya University Graduate School of Engineering School of Engineering, Furo, Chikusa, Nagoya, Aichi, Japan, Nagoya, 464-8603, Japan, Jun-Ichi Iwata, Quemix Inc., Nihonbashi, Chuo, Tokyo 103-0027, Japan, Tokyo, Japan, Kenta Chokawa, IMaSS, Nagoya University, Nagoya, Japan, Masaaki Araidai, Nagoya University, Nagoya, Aichi, Japan, Atsushi Oshiyama, Institute of Materials and Systems for Sustainability, Furo-cho, Chikusa-ku, Nagoya, 464-8603, Japan, and Kenji Shiraishi, Institue of Materials and Systems for Sustainability, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8601, Japan.

Abstract: “We performed the first-principles calculations for a nitrogen vacancy (VN) and hydrogen(H) atom in β-Si3N4 to clarify the atomistic origin of charge traps in silicon nitride (SiN) layers and charge-trapping mechanism used for 3D NAND flash memories. The present calculations showed that VN attracted H impurities and the structures where one Si dangling bond on VN is terminated by an H atom and the remaining two Si atoms form Si-Si bond (VN-H complexes) were formed in SiN layers. We investigated the electronic behavior of VN-H complexes and found that VN-H complexes act as charge traps. From our results, the atomistic origin of charge traps in SiN layers seems to be VN-H complexes.“