The ATPG Conflict-Driven Scheme for High Transition Fault Coverage and Low Test Cost

This paper presents two new conflict-driven techniques for improving transition fault coverage using multiple scan chains. These techniques are based on a novel test application scheme, in order to break the functional dependency of broadside testing. The two new techniques analyze the ATPG conflicts in broadside test generation, and try to control the flip-flops with most influence on the fault coverage.The conflict-driven method selects some flip-flops that work in the enhanced mode and distributes them into different chains. In the multiple scan chain architecture, to avoid too many scan-in pins, some chains are driven by the same scan-in pin to construct a tree-based architecture. Based on the architecture, the new test application scheme allows some flip-flops working in the enhanced mode, while most of others working in the traditional broadside mode. With the efficient conflict-driven selection method, fault coverage is improved greatly, which can also reduce test application time and compress test data volume. Experimental results show that fault coverage based on the proposed method is comparable to the enhanced scan.