Investigation and trade-offs in 3DIC partitioning methodologies: N/A

Abstract

In this work, we compare alternative 3DIC partitioning methodologies, in terms of slack, number of inter-tier vias, Tier Area Ratio (TAR) and HPWL design parameters. The popular 3DIC postplacement, bin-based Fidducia-Mattheyses (FM) partitioning flow is used as a baseline for comparison. While the latter does produce a minimum number of inter-tier vias, for a specified FM area balance, their number cannot be directly constrained. This behavior motivated us to investigate a different 3DIC partitioning scheme, based on post-placement 3D legalisation, where the legaliser is capable of spreading cells across all available tiers for minimum displacement or HPWL. In contrast to bin-based FM, in 3D legalisation, the number of inter-tier vias can be directly constrained, albeit at the expense of TAR. The 3D legalisation partitioning scheme can expose a continuous trade off between the available number of intertier vias and design parameters. An unconstrained number of vias, which produce the best 3D gains in design parameters, while constraining the numbers of vias will trade them off with lower 3D gains. Results for three 3DIC partitioning flows are presented, on four OpenCores benchmarks, and the achieved trade offs between number of inter-tier vias and slack, TAR and HPWL parameters, per flow, are described. © 2019 ACM.