Scan chain diagnostics have become more important than ever due to the increasing complexity of VLSI designs, as more and more scan latches/flip-flops are utilized in designs, especially in microprocessors. At the same time, the off-state leakage current of CMOS technology grows exponentially from one generation to the next one. This fact imposes a big challenge on the chip design, packaging, cooling, etc. However, innovative applications, based on the detection of light emission due to off-state leakage current (LEOSLC) have been developed for testing and diagnosing modern VLSI circuits. We show that LEOSLC can be used to effectively debug, diagnose, and localize defects in a broken scan chain.
['Peilin Song', 'Franco Stellari', 'Tian Xia', 'Alan J. Weger']
A novel scan chain diagnostics technique based on light emission from leakage current