Invisible delay quality - SDQM model lights up what could not be seen

The quality of delay testing focused on small delay defects is not clear when traditional fault models are used. We therefore evaluated the feasibility of using the statistical delay quality model (SDQM) - which reflects fabrication process quality, design delay quality, test timing accuracy, and test pattern quality - by using a commercial automatic test program generation (ATPG) tool to apply it to a large data set. The SDQM can also provide a measure predicting the defect level of a chip, and by simulating test patterns we show experimentally here that this measure can be calculated within a reasonable CPU time when using a reasonable amount of memory. Because we found when using SDF information to calculate path lengths accurately that the transition test patterns are not good at detecting small delay defects in long paths, a new test algorithm that detects small delay defects should be developed