Structure Design Optimization and Reliability Analysis on a Pyramidal-Shape Three-Die-Stacked Package With Through-Silicon Via
Structure Design Optimization and Reliability Analysis on a Pyramidal-Shape Three-Die-Stacked Package With Through-Silicon Via
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DOI：
10.1109/tdmr.2011.2176126
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发表时间：
2012-06
影响因子：
2
通讯作者：
F. Che;S. Lim;T. Chai;Xiaowu Zhang
中科院分区：
文献类型：
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作者：
F. Che;S. Lim;T. Chai;Xiaowu Zhang
本文从实验和数值两方面研究了金字塔形贯通硅通孔三芯片叠层封装的可靠性。最初设计的微凸点位于TSV芯片边缘的外围，当上芯片堆叠时，这会在下芯片上产生集中的弯曲力。有限元模拟结果表明，这种凸点布局在下模堆积过程中会导致下模产生较大的应力和变形。进行了三点弯曲试验，以确定模具强度。还进行了芯片堆叠实验。实验结果表明，即使在较小的堆叠力的情况下，当中模叠放时，下模会开裂，而当上模叠叠时，中模会开裂。有限元模拟、模具强度弯曲试验和芯片堆叠实验得到了一致的结果。提出了一种优化的凸台布局设计方案，即在模具中心区域增加虚拟凸台，以支撑芯片堆叠过程中产生的弯曲力。优化设计显著降低了模具的应力水平和挠度。最后，即使使用较大的堆叠力，也可以实现成功的芯片堆叠过程。
In this paper, the reliability of a pyramidal-shape three-die-stacked package with through-silicon via (TSV) is studied experimentally and numerically. The initially designed microbumps are located peripherally along the edge of the TSV die, which induces a concentrated bending force on the lower die when the upper die is stacked. Finite-element (FE) simulation results show that such bump layout induces large stress and deflection in the lower die under the die-stacking process. Three-point bend tests were conducted to determine the die strength. Die-stacking experiments were also carried out. The experimental results show that the bottom die cracks when the middle die is stacked and the middle die cracks when the top die is stacked even with a small stacking force. Consistent results have been obtained among FE simulation, die strength bend test, and die-stacking experiments. An optimal bump layout design is proposed, which adds some dummy bumps on the central area of the die to support the bending force induced by the die-stacking process. The optimal design significantly reduces the die stress level and deflection. Finally, a successful die-stacking process is achieved even using a larger stacking force.