SW-Based Transparent In-Field Memory Testing

With continuous technology scaling, both quality and reliability are becoming major concerns for ICs due to extreme variations, non-ideal voltage scaling, etc. (not to mention the business pressure leading to shorter-time to market). One-time-factory manufacturing test is not sufficient anymore, and in-field testing (e.g., periodically, at power-on, during idle times) is becoming mandatory. Due to the strict constraints of in-field test, transparent BIST is extremely attractive, since it allows to minimize test invasiveness. This paper presents a cheap, high quality and practical SW-based transparent in-field test approach for memories within a system. Instead of using hardware BIST, the proposed scheme re-uses the CPU to perform in-field testing for all memories within the system. All quality metrics of the proposed solution (such as defect coverage, test time and code size) are analyzed. Case studies using the ARM instruction set architecture are provided to demonstrate the applicability of the solution. With the proposed approach no hardware BIST is necessary and speed-related faults are tackled, whereas results show the test time complexity of the SW-based transparent tests is the same as the one of the standard hardware BIST test. Moreover, data previously present in the memory is not corrupted with, in average, only a 30% increase in test program size with respect to non-transparent SW-based test.