Direct Impact of Chemical Bonding of Oxynitride on Boron Penetration and Electrical Oxide Hardening for Nanoscale Flash Memory

We report the direct correlation between chemical bonding and the physical-electrical properties of oxynitride (SiON). Through comparing oxynitrides grown by furnace anneal and by plasma method in the low-nitrogen-concentration region (<; 16 at %), we found that the boron blocking efficiency and oxide hardening against high-field electrical stress are directly enhanced by the N-Si₃ and N-(SiOx)₃ configurations, while the Si₂-N-O configuration, in spite of the much higher nitrogen concentration, moderately degrades the hardening effect with less improvement for boron blocking. The results indicate that controlling the nitrogen bonding configuration for tunnel oxide may be a key solution to the insufficient reliability of nanoscale Flash memory.