Lin Huang and Qiang Xu CUHK Reliable Computing Laboratory (CURE)

1. Is It Cost-Effective to Achieve Very High Fault Coverage for Testing Homogeneous SoCs with Core-Level Redundancy? Lin Huang and Qiang Xu CUHK Reliable Computing Laboratory (CURE) The Chinese University of Hong Kong {lhuang,qxu}@cse.cuhk.edu.hk

2. 1 0.5 Probability 0 Test Pattern Number Observations on Manufacturing Test Cost • Traditional manufacturing test requests sufficiently high defect coverage • Manufacturing test cost - a great share of production cost • Most test patterns are for the last several percentages of defect coverage • If we are able to relax this coverage requirement , manufacturing cost can be dramatically reduced

3. Proposed Strategy • Manycore processor era provides us such an opportunity • Traditional yield-driven redundant cores aims to improve the manufacturing yield • We propose to introduce a few test cost-driven redundant cores in addition to yield-driven spares, to relax the defect coverage requirement of each core • If test cost reduction exceeds the manufacturing cost increment, the total production cost can be reduced

4. Problem Formulation • Consider • A homogeneous manycore system with m+n+s cores • s yield-driven redundancy and n test cost-driven spares • Those that contain m+n pass-test cores are sold • Eventually guarantee m cores are defect-free for sold chips to function • Given • The maximum acceptable test escape rate • The ratio between the manufacturing cost per core to its test cost • Determine sand n to achieve the minimum production cost per sold chip under product quality constraint

5. r: cost ratio of test over manufacturing n: test cost-driven redundant core number s: yield-driven redundant core number Cmanu: normalized manufacturing cost Ctest: normalized test cost Cprod: normalized production cost Case Study: A Homogeneous manycore system functions with no less than 16 defect-free cores

6. Thank you for your attention!Looking forward to seeing you at Poster 7.1