CROWNE: Current Ratio Outliers with Neighbor Estimator

Increased leakage and process variations make distinction between fault-free and faulty chips by IDDQ test difficult. Earlier the concept of Current Ratios (CR) was proposed to screen defective (outlier) chips. However, it is not capable of catching certain defects. Neighboring chips on a wafer have similar fault-free parameters that are correlated through the underlying fabrication process. Based on this observation, an alternative test metric called Neighbor Current Ratio (NCR) was proposed. NCR screens outlier chips based on their nonconformance to local variation in IDDQ. In this paper, we explore the correlation between different vectors that yield CR and NCR values. The effectiveness of NCR along with additional test parameters to screen outlier chips is evaluated using industrial test data.

• Type: Conference
• Year: 2003
• Where: DFT
• Authors: Sagar S. Sabade, D. M. H. Walker
• Keywords: Chips, DFT 2003, Hardware, Outlier Chips, Screens Outlier Chips