Abstract Chip–package interaction (CPI) has become an increasingly important reliability issue in the microelectronics industry. In order to survive the thermally induced stresses during processing or working lifetime, the complex back-end-of-line (BEOL) layer stacks must have sufficient mechanical strength. The understanding of accelerated mechanical tests performed at wafer level, such as shear microprobing, is needed to early detect the risk of failure in the final IC device. In this study, the impact of the BEOL architecture in terms of via density and metal density on the failure location and the amount of observed BEOL failures is demonstrated by performing a large statistical amount of shear microprobing combined with post-mortem focused ion beam (FIB) cross sections. The experimental results are further supported by local bump pull tests, in-situ scanning electron microscopy (SEM) micro beam bending tests and finite element modeling (FEM). A clear correlation was found between the BEOL architecture and the amount of observed BEOL fractures. It was found that the cross sectional metal area in the topmost Z–group has a stronger impact on the amount of BEOL failures compared to the low or medium, X or Y–groups respectively. This trend was explained in terms of elastic shielding effect. Furthermore, both experimental results and FEM show that the via density may play a dominant role in both crack initiation and crack growth. These findings lead to a better understanding of the robustness of interconnect structures and the stresses they can tolerate and may serve as guidelines to develop a CPI-aware design of advanced nano-interconnects.

中文翻译：

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后端架构对高级互连中芯片封装交互的影响

摘要 芯片封装交互 (CPI) 已成为微电子行业中日益重要的可靠性问题。为了在加工或工作寿命期间承受热致应力，复杂的后端 (BEOL) 层堆叠必须具有足够的机械强度。需要了解在晶圆级执行的加速机械测试，例如剪切微探针，以便及早检测最终 IC 器件的故障风险。在这项研究中，BEOL 架构在通孔密度和金属密度方面对故障位置和观察到的 BEOL 故障数量的影响通过执行大量统计量的剪切微探测结合事后聚焦离子束 (FIB) 来证明） 交叉区域。局部凹凸拉力测试进一步支持了实验结果，原位扫描电子显微镜 (SEM) 微束弯曲测试和有限元建模 (FEM)。在 BEOL 架构和观察到的 BEOL 断裂量之间发现了明显的相关性。结果表明，与低或中、X 或 Y 组相比，最顶部 Z 组中的横截面金属面积对 BEOL 故障量的影响更大。这种趋势可以用弹性屏蔽效应来解释。此外，实验结果和 FEM 都表明通孔密度可能在裂纹萌生和裂纹扩展中起主导作用。这些发现有助于更好地了解互连结构的稳健性及其可承受的应力，并可作为开发先进纳米互连的 CPI 感知设计的指南。