Optimal spare utilization for reliability and mean lifetime improvement of logic built-in self-repair

Reliability and the mean lifetime are major aspects in today´s semiconductor device manufacturing. The continuous downscaling of transistor sizes and power supplies are the root causes of higher vulnerabilities of integrated circuits against time zero process variation, time dependent degradation and random faults induced by environmental influences like particle strikes. Handling permanent faults becomes inevitably a suitable solution to guarantee high reliabilities as well as increased lifetimes. Built-in self-repair is a possible solution, which exchanges faulty units with spare parts at the costs of extra hardware. In this paper, we evaluate the influence of different replacement strategies and their resulting additional hardware structures on reliability and mean lifetime. This analytical process allows to find the optimal replacement strategy for a given system, without implementing and synthesizing each case.