各向异性静态随机存储器中的多位翻转分析研究

重离子实验结果表明,具有高线性能量转移(LET)或大角度入射的快重离子导致静态随机存储器(SRAM)中的多位翻转(MBU)比例增大,甚至超过单位翻转比例。单个离子径迹中的电荷可以沿着径向扩散数个微米,被临近的灵敏区收集后引起MBU。器件灵敏区的各向异性空间布局与离子入射方向共同影响测试器件的MBU图形特征。位线接触点的纵向隔离导致横向型成为主要的两位翻转图形;"L"型和"田"型分别是主要的三位翻转和四位翻转图形。最后,对SRAM抗MBU加固设计和实验验证方法进行了讨论。

Investigation of Multiple-bit Upsets in Anisotropic SRAM Device

Heavy ion experimental results reveal that the ratio of multiple-bit upset (MBU) in static random access memory (SRAM) increases for ions with higher linear energy transfer (LET) value or at larger angle of incidence, even exceeds the ratio of single-bit upset. The diffusion distance of charges in single ion track can be several micrometers. The MBU patterns of device under test are influenced by both the anisotropic distribution of sensitive volumes and the track direction. Horizontal configuration turns out to be the predominant double-bit upset pattern due to the vertical isolation (bit-line contacts) of adjacent sensitive volumes. L-shaped and squareshaped configurations are the main triple-bit upset and quadruple-bit upset patterns, respectively. Finally,implications for MBU hardness strategies and evaluation methods are discussed.