A reconfiguration-based defect-tolerant design paradigm for nanotechnologies

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He, Chen

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Entering the nanometer era, a major challenge to current design method ologies and tools is how to effectively address the high defect densities pro jected for emerging nanotechnologies. To this end, in this dissertation we propose a reconfiguration-based defect-tolerant design paradigm for defect prone nanoelectronic technologies. In our paradigm, designs are mapped into a nanofabric comprised of reconfigurable regions, architected using a suitable hierarchy of design abstractions, so as to meet the target yield with best ex pected performance. The new design goal is thus to devise an appropriate structural/behavioral decomposition which improves scalability by constrain ing the defect mapping and reconfiguration process to small fabric regions, while meeting a desired probability of successful instantiation, i.e., yield. A key feature of our proposed nanofabric architecture is that it en ables the defect mapping and configuration tasks to be performed within the nanofabric itself, eliminating the costly per-chip offline processing. Specifically, we have devised a novel group testing method that can systematically identify defective components and/or connectivity in a fabric region. It enables the entire fabric to be tested and configured in a scalable way, using a relatively small number of easily configured triple-modular-redundancy (TMR) test tiles executing concurrently on different regions of the target nanofabric. Moreover, our proposed design paradigm offers a rich framework in which critical trade-offs among performance, yield, and complexity can be explored. The probabilistic nature of these tradeoffs has required us to in troduce a new class of ‘reliability-aware’ high-level synthesis (HLS) problems. In particular, rather than carefully optimizing a single (‘deterministic’) solu tion, as done in traditional HLS, our approach requires the joint synthesis and optimization of a sufficiently large family of alternative solutions, so as to achieve the specified target yield, with best-expected performance. We have developed a Reliability-Aware Synthesis framework for NANOfabrics (RAS NANO), aimed at systematically solving this new class of ‘reliability-aware’ HLS problem. It enables designers to effectively explore the complex prob abilistic design space associated with the new reconfiguration-based defect tolerant design paradigm.