Comprehensive investigations on charge diffusion physics in SiN-based 3D NAND flash memory through systematical Ab initio calculations

摘要

Aiming at comprehensive understandings on the underlying physics of the charge diffusion in charge-trap (CT) 3D NAND flash memories, various hydrogen (H) and oxygen (O) incorporated defects in SiN CT layer are studied via ab initio calculations. It is found that, O atom incorporated defects are extremely shallow (~0.18eV) and could be the main reason of fast charge loss, while H atom incorporated defects (VN-H, SiN-H) should be the dominant traps in SiN CT layer. More importantly, though H passivation is effective to eliminate shallow traps, excessive H will generate other shallow traps on the contrary. Then, with further discussions on H bond stabilities, it is proposed that replacing H with Deuterium (D) could be an effective approach to suppress shallow trap generations during Write/Erase cycling and improve memory reliabilities.