Storage-Based Built-In Self-Test for Gate-Exhaustive Faults

Built-in self-test (BIST) approaches are suitable for in-field testing since they do not require a tester for storage and application of test data. They also reduce the security vulnerabilities associated with loading and unloading of external test data into scan chains. As technologies evolve, in-field testing needs to address more complex defect and aging mechanisms that require specific deterministic tests. This can be addressed by BIST approaches that store test data on-chip and use the data for on-chip generation of both random and deterministic tests. In this case, there is a tradeoff between the amount of stored test data and the comprehensiveness of the test set that can be applied. This article explores this tradeoff in a specific context that has the following main features: 1) the initial stored test data is based on a stuck-at test set; 2) the target faults are single-cycle gate-exhaustive faults; and 3) the stored test data is enhanced gradually by test data based on a gate-exhaustive test set to increase the coverage of gate-exhaustive faults.