Reliability/yield trade-off in mitigating “no trouble found” field returns

With VLSI scaling, “no trouble found” or NTF field returns have increased due to the dominance of soft defects over hard defects. An analysis of networking and DSP NTF field returns shows outlying behavior in not only product parameters but also on-die process parameters revealing new mitigation opportunities. The resulting yield hit is demonstrated to be minor <;0.5% to catch NTFs that can be >50% field returns with high debug cost.