Delay uncertainty and signal criticality driven routing channel optimization for advanced DRAM products

Signal delay uncertainty induced by crosstalk is a critical challenge to the physical design of long interconnect channels in DRAM products at the 2× and 1× technology nodes. Due to severe cost challenges in a high-volume, commodity market, layout resources including channel width, buffers, and number of metal routing layers are extremely scarce. We describe a new channel optimizer that reduces crosstalk-induced delay uncertainty, weighted by signal criticality and aware of signal activity correlations (e.g., to reduce delay uncertainty by mutual shielding). Instead of the typical signal net permutation strategy, we apply (pessimistic) timing-driven swizzling to minimize the delay uncertainty cost function. Contributions of this work include (1) an accurate and efficient analytical crosstalk delay calculator, (2) scalability up to hundreds of signals and tracks in the routing channel through use of greedy and decomposition strategies as well as a pair-swapping approach, and (3) experimental studies that demonstrate up to 24% reduction of the worst-case criticalityweighted delay uncertainty (or, 34ps of absolute delay uncertainty reduction) compared with the typical signal permutation approach.