Department: Electrical & Computer Engineering
Faculty Advisor(s): Andrew B. Kahng

Primary Student
Name: Jiajia Li
Email: jil150@ucsd.edu
Phone: 858-822-5003
Grad Year: 2016

Student Collaborators
Kwangsoo Han, kwhan@eng.ucsd.edu

3D logic-logic integration is an important future lever for continued cost and density scaling value propositions in the semiconductor industry. In the 3DIC context, several works have proposed ?mix-and-match? of multiple stacked die, according to binning information, to improve overall product yield. However, each of the stacked die in these works is independently designed: there is no holistic ?design for eventual stacking? of any of the die. Separately, many approaches have been proposed for design partitioning and implementation with multiple die, including 3D stacked-die implementation. However, the signoff criteria used to implement such a multi-die solution must necessarily validate timing correctness for all combinations of process conditions on the multiple die. To our knowledge, no previous work has examined the fundamental issue of design partitioning and signoff specifically for mix-and-match die stacking. In this work, we study performance improvements of 3DIC implementation that leverage knowledge of mix-and-match die stacking during manufacturing. We propose partitioning methodologies to partition timing-critical paths across tiers to explicitly optimize the signed-off timing across the reduced set of corner combinations that can be produced by the stacked-die manufacturing. These include both an ILP-based methodology and a heuristic with novel maximum-cut partitioning, solved by semidefinite programming, and a signoff timing-aware FM optimization. We also extend two existing 3DIC implementation flows to incorporate mix-and-match-aware partitioning and signoff, demonstrating the simplicity of adopting our techniques. Experimental results show that our optimization flow achieves up to 16% timing improvement as compared to the existing 3DIC implementation flow in the context of mix-and-match die stacking.

Industry Application Area(s)

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