IC Physical Design Methodologies for Advanced Process Nodes
- Author(s): Han, Kwangsoo
- Advisor(s): Kahng, Andrew B.
- et al.
Next-generation applications in mobile, automotive, internet of things, robotic, artificial intelligence, etc. domains require the development and integration of advanced systems-on-chip (SOCs) that deliver ever-higher performance with much lower power. Thus, Moore's Law continues to be necessary, and innovations are needed beyond this law to help manage performance, power, area and cost (PPAC) for integrated-circuit (IC) design. Among the steps in the typical IC design flow, physical design implementation critically impacts PPAC. However, in concert with continuation of the Moore's Law trajectory, IC physical design encounters new challenges such as patterning restrictions due to manufacturing limits, severe process variation, and escalating interconnect RC delay. This thesis presents techniques to mitigate these challenges, grouped into three main thrusts: (i) manufacturing-aware design methodologies, (ii) process-aware design methodologies, and (iii) interconnect-aware design methodologies.
Multiple-patterning techniques play a key role in the quest to print ever-smaller features for continued technology scaling in advanced nodes. However, the use of multiple-patterning significantly raises the number of extra steps for patterning as well as layout constraints needed for patternability; this causes an explosion of design rules and a loss of achievable layout density. To manage the onslaught of complex design rules arising from multiple-patterning, the manufacturing-aware design methodologies thrust of this thesis proposes approaches to optimize 2D block mask layout for minimum timing degradation, perform detailed placement to fix complex front-end-of-line (FEOL) design rule violations, and evaluate complex back-end-of-line (BEOL) design rule impact.
Design variability due to manufacturing process variations has significant impact on the quality and yield of modern IC designs. Escalating process variation with new device architectures and manufacturing techniques (e.g., FinFET, multiple-patterning, etc.) required for node scaling results in the rapid increase of pessimism and overdesign. To mitigate the impact of severe process variation, the process-aware design methodologies thrust of this thesis presents approaches to optimize top-level clock tree for OCV minimization, reduce skew variation in the clock network, and perform partitioning in 3DIC that leverages a priori knowledge of inter-die variation.
In advanced technology nodes, interconnect RC delay becomes more and more dominant. The continuous rapid increase of interconnect RC leads to not only performance loss from interconnect delay increase, but circuit power and area degradation as well, due to exponential increase in the number of buffers and drivers. To mitigate the escalating interconnect RC delay, the interconnect-aware design methodologies thrust of this thesis proposes approaches to co-optimize wirelength and pathlength in routing, studies optimal wirelength-skew tradeoff and remaining suboptimality in interconnect tree constructions, and performs optimal generalized H-tree construction with buffering.