An industrial evaluation of DRAM tests

DRAM production tests are currently necessary to reach a defect-per-million level that approaches the single-digit numbers. This implies that a single memory test is insufficient; rather, a set of tests is necessary. This application of 40 well-known memory tests to 1,896 1-Mbyte /spl times/ 4 DRAM chips, used up to 48 different stress combinations with each test. The results show the importance of selecting the right stress combination, and that the theoretically better tests - those covering more different functional faults - also have higher fault coverage.