Hazard-Based Functionally Possible Transition Faults With High Functional Switching Activities

Defects that are manifested during functional operation, also referred to as functionally possible, have been shown to be responsible for the occurrence of silent data corruption (SDC) in large datacenters. The defects may have occurred because of high workloads that speed up the process of chip aging. This motivated the focus of earlier works on functionally possible faults in sites that are subjected to high functional switching activities. The functional switching activity in earlier works was based on transitions. Pulses were not considered in this context. This article defines the notion of a hazard based functional switching activity that captures the conditions for pulses to occur during functional operation. It then revisits the hazard based detection conditions for transition faults, under which faults are activated using pulses instead of transitions. The article describes a procedure that selects target faults that may be susceptible to aging because of pulses, and a test generation procedure for the target faults. Experimental results for benchmark circuits demonstrate the potential importance of considering hazard based faults. The results also demonstrate that only small numbers of tests need to be added to a conventional transition fault test set for the selected hazard based transition faults.