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

Abstract

Abstract-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.Index Terms-Bit-oriented memories (BOMs), data backgrounds (DBs), fault models (FMs), memory tests, word-oriented memories (WOMs).

PPM Reduction on Embedded Memories in System on Chip

“…March SAM is designed to target intra-word coupling faults and faults due to the interference between I/O paths of a single word. But, the test also detect the majority of static faults [37]. This can explain its high FC.…”

“…March SAM [37] is developed to target intra-word coupling faults, which are coupling faults that take place between memory cells that belong to the same memory word, and faults due to the interference between I/O paths of the same word. March SAM requires the use of fx AD and special DBs that are different from the standard ones; see for more details [37].…”

“…March SAM requires the use of fx AD and special DBs that are different from the standard ones; see for more details [37]. The test length is [1 + 28 * log 2 (B)] * n B where B denotes the word size.…”

BIST enhancement for detecting bit/byte write enable faults in SOC SRAMs

“…These consist of four extra tests that are added, based on our experience in the field of memory testing, to detect some specific faults or some unmodeled/non-understood faults; they are given in the second bottom block of Table I. • March SAM [23] is developed to target intra-word coupling faults, which are coupling faults that take place between memory cells that belong to the same memory word, and faults due to the interference between I/O paths of the same word. March SAM requires the use of fx AD and special DBs that are different from the standard ones; see for more details [23].…”

“…• March SAM [23] is developed to target intra-word coupling faults, which are coupling faults that take place between memory cells that belong to the same memory word, and faults due to the interference between I/O paths of the same word. March SAM requires the use of fx AD and special DBs that are different from the standard ones; see for more details [23]. The same test used with other stresses (e.g., sDB) will not be able to detect such faults.…”