Modeling Yield, Cost, and Quality of a Spare-Enhanced Multicore Chip

It becomes increasingly difficult to achieve a high manufacturing yield for multicore chips due to larger chip sizes, higher device densities, and greater failure rates. By adding a limited number of spare cores and wires to replace defective cores and wires either before shipment or in the field, the effective yield of the chip and its overall cost can be significantly improved. In this paper, we first model the yield of a multicore chip that incorporates both spare cores and spare wires. Then, we propose a quality metric for an NoC, and model the system yield subject to a given quality constraint. We also model the manufacturing and service costs of a multicore chip and show that a spare scheme can significantly improve the quality, increase the yield, reduce the overall cost, and substitute for the burn-in process. We illustrate that, in a spare-enhance system on a chip with high-quality in-field recovery capability, the reliance on high quality manufacturing testing can be significantly reduced. We also demonstrate that the overall quality of a mesh-based NoC depends more on the reliability of the inner links than the outer links; therefore, nonuniform spare wire distribution is sometimes more effective and cost efficient than a uniform approach.