Reliable Power Grid Network Design and Optimization Considering Physics-Based EM Models (Tutorial)

Long-term reliabilities such as electromigration (EM) induced failures in integrated circuits are expected to grow rapidly with shrinking feature sizes in new technology nodes and novel solutions to address reliability at different levels. This talk presents a new power grid network design and optimization technique that considers the new EM immortality constraint due to EM void saturation volume for multi-segment interconnects. When a void is formed, it is considered to be a failure in traditional EM models. However, this is quite a conservative assumption as a void may never grow to sufficient volume to make a significant change to the wire resistance. By considering saturation volume for multisegment interconnects wires, we can remove such conservativeness in the EMaware on-chip power grid design. Along with another new proposed immortality constraint for the EM nucleation phase for multi-segment wires, I will show that both EM immortality constraints can be naturally integrated into the existing programming-based power grid optimization framework. To mitigate the overly conservative nature of the optimization formulation, I will further explore two strategies: first, we size up failed wires to meet one of the immortality conditions subject to design rules; second, I will consider the EM-induced aging effects on power supply networks for a target lifetime, which allows some short-lifetime wires to fail and optimizes the rest of the wires. Last, not least, I will present our recent work using deep neural networks to model the full-chip EM-induced IR drop and leveraging of the differential feature of DNN for fast sensibility calculation for sensitivity-guided full-chip EM-aware power grid optimization.