New data-background sequences and their industrial evaluation for word-oriented random-access memories

This paper improves upon the state of the art in the testing of intraword coupling faults (CFs) in word-oriented memories. It first presents a complete set of fault models for intraword CFs. Then, it establishes the data background sequence and tests for each intraword CF, as well as a test with complete fault coverage of the targeted faults. All introduced tests will be evaluated industrially, together with the most well-known memory tests. The tests will be applied to big arrays with an interleaved bit-organization as well as to small arrays with an adjacent bit-organization in order to investigate the influence of the memory organization on the intraword CFs. The test results show that the intraword CFs are also significantly important for interleaved memories, even when the cells within a single cell are not physically adjacent. This is due to coupling between the adjacent bit lines and word lines running across the memory array. The paper concludes that intraword CFs should be considered for any serious test purpose or leave substantial defects undetected, especially when considering a high-volume production and a very low defect-per-million (DPM) level.