EM-Aware Design: from Physics to System Level (Tutorial)

In this tutorial, I will present some of the recent research works in my research lab (VSCLAB) at UC Riverside. First, I will review a recently proposed physics-based three-phase EM model for multi-segment interconnect wires, which consists of nucleation, incubation, and growth phases to completely model the EM failure processes in typical copper damascene interconnects. The new EM model can predict more accurate EM failure behaviors for multi-segment wires such as interconnects with reservoir and sink segments. Second, I will present newly proposed fast aging acceleration techniques for efficient EM failure detections and validation of practical VLSI chips. I will present the novel configurable reservoir/sink-structured interconnect designs in which the current in the sink segment can be activated/deactivated dynamically during operation. In this way, the stress conditions of the interconnect wires can be increased and the lifetime of the wires can be reduced significantly. Afterward, I will present the compact dynamic EM models for general multi-segment interconnect wires and voltage-based EM immortality check algorithm for general interconnect trees. Then I will present a fast 2D stress numerical analysis technique based on the Krylov subspace and finite difference time domain methods (FDTD) for general interconnect wire’s structure. The proposed numerical analysis method can lead to 100X speedup over the simple FDTD method and can be applied to any interconnect structures for all the EM wear-out phases. Then I will focus on the system-level dynamic reliability management (DRM) techniques based on the newly proposed physics-based EM models. I will show several recent works of the EM-aware DRM for lifetime optimizations for dark-silicon, embedder/real-time systems, and 3D ICs to improve the TSV reliability. Last, not least, I will present the work to consider special temperature gradient impacts on EM due to the Joule heating effect. The spatial temperature gradient induced metal atom migration effects, also called temperature migration (TM), was shown to be as significant as the EM itself as technology advances. In our work, I will show how to consider TM effects in both existing EM immortality check and semi-analytic based approaches for the first time.