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Self-Compensating Design for Reduction of Timing and Leakage Sensitivity to Systematic Pattern-Dependent Variation.
- Source :
- IEEE Transactions on Computer-Aided Design of Integrated Circuits & Systems; Sep2007, Vol. 26 Issue 9, p1614-1624, 11p, 4 Black and White Photographs, 7 Charts, 6 Graphs
- Publication Year :
- 2007
-
Abstract
- Critical dimension (CD) variation caused by defocus is largely systematic with dense lines ‘smiling’ through focus while isolated lines ‘frown.’ In this paper, we propose a new design methodology that allows explicit compensation of focus-dependent CD variation, in particular, either within a cell (self-compensated cells) or across cells in a critical path (self-compensated design). By creating iso and dense variants for each library cell, we can achieve designs that are more robust to focus variation. Optimization with a mixture of dense and iso cell variants is possible, both for area and leakage power in timing constraints (critical delay), with the latter an interesting complement to existing leakage-reduction techniques, such as dual-Vth. We implement both a heuristic and mixed-integer linear-programming (MILP) solution methods to address this optimization and experimentally compare their results. Results indicate that designing with a self-compensated cell library incurs 12% area penalty and 6% leakage increase over a baseline library while compensating for focus-dependent CD variation (i.e., the design meets timing constraints across a large range of focus variation). We observe 27% area penalty and 7% leakage increase at the worst case defocus condition using only single-pitch cells. The area penalty of circuits after using both the heuristic and MILP optimization approaches is reduced to 3% while maintaining timing. We also apply the optimization to leakage, which traditionally shows very large variability due to its exponential relationship with gate CD. We conclude that a mixed iso/dense library that is combined with a sensitivity-based optimization approach yields much better area/timing/leakage tradeoffs than using a self-compensated cell library alone. Self-compensated designs show 25% less leakage power on average at the worst defocus condition compared to a design employing a conventional library for the benchmarks studied. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 02780070
- Volume :
- 26
- Issue :
- 9
- Database :
- Complementary Index
- Journal :
- IEEE Transactions on Computer-Aided Design of Integrated Circuits & Systems
- Publication Type :
- Academic Journal
- Accession number :
- 26479647
- Full Text :
- https://doi.org/10.1109/TCAD.2007.895759