A cautionary tale of soft errors induced by SRAM packaging materials
A cautionary tale of soft errors induced by SRAM packaging materials
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SRAM 封装材料引起的软错误的警示故事
DOI：
10.1109/tdmr.2005.855825
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发表时间：
2005
影响因子：
2
通讯作者：
S. Hareland
中科院分区：
文献类型：
--
作者：
J. Wilkinson;S. Hareland
现代植入式医疗设备使用各种电路和架构功能来确保高水平的数据完整性，特别是与患者治疗和安全相关的数据。由于现代植入式医疗设备，如植入式心律转复除颤器（icd）和起搏器，依赖于集成电路（IC）技术，它们很容易受到电离辐射源的软误差的影响。可植入器件中采用的集成电路技术通常使用CMOS技术，由于晶体管泄漏，功耗和可靠性要求的压倒性关注，该技术比最先进的CMOS工艺落后几代。对于CMOS技术和现代电路设计工艺，IC对α粒子辐射的敏感性是一个已知的问题。对于功耗要求，植入式医疗设备的工作电压通常也低于标准电子产品，因此这会对α诱导的软错误率（SERs）产生更大的影响。本文将详细介绍对一种新的SRAM封装进行的案例研究，该封装可能用于收集诊断数据，其中使用了各种测试方法来隔离导致α诱导软误差的材料。测试程序在倒装芯片配置中使用了许多标准SRAM组件，并使用测试板在相对较短的时间内收集大量数据。SRAM测试芯片也通过硼屏蔽测试室与热中子隔离。宇宙射线诱导的高能中子的贡献在以前的数据解释中被描述和考虑。在高发射材料下，显示了软误差与凹凸布局的相关性，并通过建模验证了这些误差的范围。还将展示使用低α发射焊料和下填充材料来减少软误差。如果没有下填充，高α发射焊料，电路板外围材料和电路板本身的残余误差可以显示为影响系统的总SER。
Modern implantable medical devices use a variety of circuit and architectural features to ensure high levels of data integrity, especially data related to patient therapies and safety. Since modern implantable medical devices, such as implantable cardioverter defibrillators (ICDs) and pacemakers, rely on integrated-circuit (IC) technology, they are susceptible to soft errors from ionizing radiation sources. The IC technology employed in implantable devices typically uses a CMOS technology that is several generations behind the most advanced CMOS processes due to the overwhelming concern of transistor leakage, power consumption, and reliability requirements. For CMOS technology and modern circuit design processes, IC susceptibility to alpha-particle radiation is a known concern. For power consumption requirements, the operating voltages of implantable medical devices are also typically lower than standard electronic products, so this can have a much greater impact of alpha-induced soft-error rates (SERs). This paper will detail a case study performed on a new SRAM package, potentially for collecting diagnostic data, in which a variety of test methods was used to isolate materials contributing to alpha-induced soft errors. The test procedure utilized numerous standard SRAM components in a flip-chip configuration, with a test board to gather large amounts of data in a relatively short time period. SRAM test chips were also isolated from thermal neutrons by using a boron-shielded test chamber. Contributions from cosmic-ray-induced energetic neutrons were previously characterized and taken into account during the interpretation of the data. The correlation of soft errors to bump layout is shown with high-alpha-emitting materials, and the range of these errors is verified with modeling. The use of low-alpha-emitting solders and underfill materials for the reduction of soft errors will also be shown. Without underfill, residual errors from high-alpha-emitting solders, materials on the periphery of the circuit board, and the circuit board itself can be shown to impact the total SER of the system.