浮栅器件的单粒子翻转效应

Study on Single Event Upset of floating gate device

摘要:

基于中国原子能科学研究院的HI-13加速器，利用不同线性能量传输(LET)值的重离子束流对4款来自不同厂家的90 nm特征尺寸NOR型Flash存储器进行了重离子单粒子效应试验研究，对这些器件的单粒子翻转(SEU)效应进行了评估。试验中分别对这些器件进行了静态和动态测试，得到了它们在不同LET值下的SEU截面。结果表明高容量器件的SEU截面略大于低容量的器件；是否加偏置对器件的翻转截面几乎无影响；两款国产替代器件的SEU截面比国外商用器件高。国产替代器件SEU效应的LET阈值在12.9 MeV·cm²/mg附近，而国外商用器件SEU效应的LET阈值处于12.9~32.5 MeV·cm²/mg之间。此外，针对单粒子和总剂量效应对试验器件的协同作用也开展了试验研究，试验结果表明总剂量累积会增加Flash存储器的SEU效应敏感性，分析认为总剂量效应产生的电离作用导致了浮栅上结构中的电子丢失和晶体管阈值电压的漂移，在总剂量效应作用的基础上SEU更容易发生。

Abstract:

Four types of NOR Flash memories from different manufacturers with 90 nm feature sizes are studied, based on the HI-13 accelerator of the China Academy of Atomic Energy. Aiming to evaluate the Single Event Upset(SEU) effect for those memories, heavy-ion with different Linear Energy Transfer(LET) values is utilized to irradiate the devices. Both static and dynamic tests are performed to obtain the SEU cross-section of the device. Test results show that the memory with large capacities has a slightly bigger SEU cross-section than the devices with small capacities. There is almost no impact on the SEU cross-section of the device with or without bias. The SEU cross-section of the domestic alternative devices is bigger than that of two foreign commercial devices. The LET threshold of the domestic alternative devices is nearly at 12.9 MeV·cm²/mg, while that value of foreign commercial devices between 12.9~32.5 MeV·cm²/mg. The SEU cross-section results from static and dynamic tests have good consistency, which indicates test mode has no obvious influence on SEU effect. In addition, the synergistic effects of Single Event Effect(SEE) and Total Ionizing Dose(TID) effect for Flash memory are also studied, the results show that TID dose will increase the sensitivity of the device to SEE. The analysis shows that the ionization caused by the TID effect leads to the electron leakage from the floating gate and the drift of transistor threshold voltage, therefore SEU is more likely to occur on the basis of TID effect.