Design of a BIST RAM with row/column pattern sensitive fault detection capability

A novel fault model is developed for random-access memories for a class of pattern-sensitive faults called row/column weight-sensitive faults. A test procedure is developed to detect faults from the defined fault model. This test sequence also tests the memory array for the 5-cell-neighborhood static pattern-sensitive faults and other faults, such as stuck-at-faults and coupling faults. A built-in self-test (BIST) version of the algorithm has been implemented by completing the logic design and layout in 2-μm CMOS technology. The silicon area overhead for a 4M RAM is as little as 0.8%. The number of extra pins can be as low as one if clock is available on-chip. The number of extra pins can be as low as one if clock is available on-chip. The delay introduced to the normal paths, as estimated by simulation tools, is small and can be reduced even further