在倒装芯片的单粒子效应防护设计验证中, 重离子在到达器件敏感区前要经过几百微米的衬底材料, 需要计算器件敏感区中离子的线性能量传输(LET)值。采用兰州重离子加速器加速的 55 MeV/μ58Ni离子对基于倒装的 Xilinx公司550万门现场可编程门阵列(FPGA)实现的典型系统的单粒子效应防护设计进行了试验验证, 采用 SRIM、FLUKA和 GEANT等不同方法对试验中的 LET值进行了分析, 同时将 SRIM分析的典型结果与基于磁偏转飞行时间法的试验数据进行了比较, 发现与现有的重离子分析结果有一定差异。因此在防护验证中采用离子 LET作为主要参数的情况下, 应对重离子(尤其是高能段 )的 LET的计算方法进行约定, 以规范试验过程, 增强数据的可比性。

Linear Energy Transfer(LET) of heavy ion must be calculated in verification test especially for flip-chip Static Random Access Memory(SRAM)-based Field Programmable Gate Array(FPGA), in which the heavy ions must cross through several hundred micrometer of silicon substrate before reaching the sensitive volume. Single event effect mitigation of typical application on flip-chip SRAM-based FPGA is verified by using 55 MeV/μ58Ni ions accelerated by Heavy Ions Research Facility in Lanzhou(HIRFL).The LET of 58Ni ions is calculated by Stopping Range Ions Matter(SRIM), FLUktuierendeKAskade(FLUKA) and Geometry and Tracking(GEANT) software tools and the differences are analyzed. The LET of several typical ions calculated by using SRIM also are compared with that measured by B-TOF(Magnetic Time-of-Flight) method. It is suggested that LET calculation method or software tools should be specified(especially forhigh energy ions), as LET is a major Figure of Merit(FOM) of single event effect sensitivity.