Optimizing Decoupling Capacitors in 3D Circuits for Power Grid Integrity

This article studies one of the EDA problems for 3D IC design. The article presents a design automation solution for power grid optimization in 3D ICs. The authors propose a congestion-aware 3D power supply network optimization algorithm, which applies a sequence-of-linear-programs-based method to optimize the power grid design. We explore the trade-offs between MIM decaps and traditional CMOS decaps in chip design, and we propose a congestion-aware 3D power supply network optimization algorithm to optimize this trade-off. One of the novel features of our work is that it optimizes the power supply network using both conventional CMOS decaps and metal insulator-metal (MIM) decaps. However, because MIM decaps are built between layers of metal interconnects, they present routing blockages to nets that attempt to cross them, and therein lies the trade-off. The properties of MIM decaps make them attractive for both 2D and 3D chips, but we pay particular attention to the 3D decap problem in this article because, first, the power integrity problem is particularly critical in 3D, and requires novel approaches that leverage advances in materials, and second, the added complexity of handling routing blockages in a constrained environment makes the 3D problem especially challenging.