Fig. 1. (a) Diagram of SONOS structure; (b) 2 × 2 bit flash cells mini-array and the TEM cross-section.(a) SONOS结构示意图; (b) 2 × 2位的闪存单元微阵列及其TEM横截面

Fig. 2. I-V characteristics of the programmed and erased single SONOS flash cell after total ionizing dose irradiation by ⁶⁰Co-γ rays. ⁶⁰Co-γ射线总剂量辐照后, 编程态和擦除态的SONOS闪存单元的I-V特性变化规律

Fig. 3. (a) Threshold voltage and normalized memory window, and (b) stand-by current of the programmed and erased single flash cell after total ionizing dose irradiation by ⁶⁰Co-γ rays. 编程态和擦除态闪存单元的(a)阈值电压和归一化的存储窗口, 以及(b)静态电流随⁶⁰Co-γ射线总剂量辐照的变化规律

Fig. 4. I-V characteristics of the programmed and erased single flash cell after total ionizing dose irradiation by 10 keV X-rays. 辐射源为10 keV X射线下编程态和擦除态闪存单元的I-V特性变化规律

Fig. 5. (a) Threshold voltage and normalized memory window, and (b) stand-by current of the programmed and erased single flash cell after total ionizing dose irradiation by 10 keV X-rays.编程态和擦除态闪存单元的(a)阈值电压和归一化的存储窗口, 以及(b)静态电流随10 keV X射线总剂量辐照的变化规律

Fig. 6. Diagram of MT’s SONOS structure constructed in Sentaurus TCAD tool, with main physical parameters derived from the cross-section TEM information in Fig. 1. 在Sentaurus TCAD中构建MT的SONOS结构, 其主要物理参数来自于图1中的TEM截面信息

Fig. 7. Energy band diagram of programmed SONOS device based on Fig. 6, which illustrates sub-physical processes of total ionizing dose effect. 基于图6获得编程态SONOS器件能带图, 并标示出其电离总剂量效应的子物理过程

Fig. 8. Sub-threshold slopes of the programmed and erased single flash cell after total ionizing dose irradiation by 10 keV X-rays.辐射源为10 keV X射线下编程态和擦除态闪存单元的亚阈值斜率变化规律

Fig. 9. (a) MT top view with the leakage paths at the channel edges; (b) cross-section of MT along line A–A' indicates that MT can be considered as a main transistor in parallel with two parasitic transistors. The formation of the inverse layer along the isolated oxide leads to the generation of parasitic currents. (a)闪存单元中MT的布局简图和沟道边缘的漏电路径; (b)沿虚线A—A', MT可等效成一个主晶体管与两个寄生晶体管的并联, MT靠近隔离氧化物处反型层的形成导致寄生电流产生

Fig. 10. MT device model established by Geant 4 tool.Geant 4中建立的MT器件模型

Fig. 11. Dose enhancement effect of X-rays on high-Z materials, simulated by Geant 4 tool. Geant 4工具模拟高Z材料与X射线剂量增强效应的关系

Table 1. Operation conditions of the SONOS single flash cell.