LaON/SiO2和HfON/SiO2双隧穿层MONOS存储器存储特性的比较

本文对比研究了LaON/SiO₂和HfON/SiO₂双隧穿层MONOS存储器的存储特性. 实验结果表明，LaON/SiO₂双隧穿层MONOS存储器具有较大的存储窗口，快的编程/擦除速度及好的疲劳和保持特性. 其机理在于LaON较大的介电常数有效提高了编程/擦除过程中载流子的注入效率，较小的O 扩散系数减少了界面陷阱，从而减少了保持期间存储电荷通过陷阱辅助隧穿的泄漏. 而且N的结合在界面附近形成了强的La-N，Hf-N 和O-N键，可有效降低编程/擦除循环应力对界面的损伤，使器件具有好的疲劳特性. 此外，研究了退火温度对存储特性的影响，结果表明800 ℃退火样品的存储特性比700 ℃退火的好，这是因为800 ℃时NO退火可在LaON（HfON）中引入更多的N，且能更好释放应力，使介质中缺陷减少. 关键词： MONOS 双隧穿层 LaON HfON

Comparison between memory characteristics of MONOS memory with LaON/SiO2 or HfON/SiO2 as dual-tunnel layer

Memory characteristics of MONOS memory with LaON/SiO₂ or HfON/SiO₂ as dual-tunnel layer were comparatively investigated. Experimental results show that the MONOS memory with LaON/SiO₂ as dual-tunnel layer exhibits large memory window, high program/erase (P/E) speed, good endurance and retention properties. The basic mechanism lies in the large dielectric constant of LaON which increases the injection efficiency of carriers during programming/erasing, the smaller Oxygen diffusion coefficient in LaON which leads to the reduction of interface traps and thus the leakage of stored charges through trap-assisted tunneling during retention. Moreover, strong La-N, Hf-N and O-N bonds are formed at/near the interface due to Nitrogen incorporation, which effectively decreases the damages of the P/E cycle stress to the interface, and thus achieves excellent endurance. In addition, impacts of annealing temperatures on characteristics of MONOS memory were investigated. It is demonstrated that the memory annealed at 800 ℃ has better memory properties than that annealed at 700 ℃, which is attributed to the fact that the 800 ℃ NO annealing can incorporate more N into LaON (HfON), and well release strains, thus reducing defects in these dielectrics.
Keywords： MONOS dual-tunnel layer LaON HfON