DFT方法研究掺杂氮化硅对SONOS器件保持性能的作用

Investigating the effect of doping amorphous silicon nitride on retention characteristics of SONOS device by DFT calculation

可通过对氮化硅层掺杂来改变俘获电荷的缺陷种类和数量的方法,改善SONOS非挥发性存储器件的保持性能.建立无定形氮化硅和氧、硫、磷、氟或氯掺杂氮化硅中缺陷的簇模型;根据第一性原理的密度泛函理论(DFT),对缺陷的簇模型结构优化并计算能量,得到缺陷俘获电荷过程的能量变化.发现缺陷俘获电子的能力比俘获空穴的能力好,电子释放过程应对温度敏感,而空穴释放过程主要由隧穿机理控制.预测与氧氮化硅一样,硫或磷掺杂氮化硅代替氮化硅作为SONOS器件的电荷储存层,可改善器件的保持性能.

Retention characteristics of SONOS non-volatile memory（NVM）device is expected to be improved by doping silicon nitride to change the type and number of defects which traps charge.Firstly,cluster models of defects in amorphous silicon nitride with and without doping special element,such as oxygen,sulfur,phosphorus,fluorine or chlorine,are built.By density functional theory（DFT）of first-principles,positions of all atoms of the cluster are optimized,and energies of these clusters are calculated.Energy changes of charge capturing processes for various defects are obtained.The calculational data can provide references for investigating discharge mechanism and improving charge retention on nonvolatile memory device.The capability of capturing electrons for all defects is usually better than capability of capturing holes.The electron discharge process should be sensitive to temperature,but the hole discharge process may be mainly controlled by tunneling mechanism.Like silicon oxynitride,silicon nitride doped with sulfur or phosphorus is promising for improving charge retention characteristics of SONOS device,due to more defects having better capability of capturing electrons.