Diagnosis of Logic-to-chain Bridging Faults

We propose five logic-to-chain bridging fault models, which involve one net in the combinational logic and the other net in the scan chain. Test results of logic-to-chain bridging faults, unlike any existing fault, depend on the previous scan inputs as well as primary inputs. An accurate diagnosis technique is presented to locate logic-to-chain bridging faults. In addition, a bridging pair extraction algorithm is proposed to quickly extract bridging net pairs from the layout. Experimental results on ISCAS benchmark circuits show that, on the average, logic-to-chain bridging faults can be diagnosed within an accuracy of three bridging pairs. The technique is still applicable when only ten failing patterns are recorded on the tester.