Bottom Nitridation Engineering of Multi-Nitridation ONO Interpoly Dielectric for Highly Reliable and High Performance NAND Flash Memory

The various methods of multi-nitridation ONO to improve NAND flash memory have been demonstrated in this paper. Excellent cell performance and reliability are obtained compared to convention ONO: (1) 1.9 V program voltage reduction owing to 23 A EOT (equivalant oxide thickness) reduction (2) More than 20% tighter cell Vt distribution width and 30% narrower Vth shift after 10 K cycling can be achieved by supressing ONO bird's beak encroachment of gate re-oxidation by floating gate (FG)/top oxide nitridation. MN-ONO is a promising technology for high density NAND flash beyond 40 nm generation.