| 摘要 |
PURPOSE:To efficiently estimate the type of factors of bit failure and the generation probability by calculating the failure occurrence frequency ratio of both 1-bit and two-bit failures from factors for causing both failures simultaneously and obtaining the relative relationship of the occurrence probability of 1-bit and two-bit failures. CONSTITUTION:A first factor for causing 1-bit failure and a second factor for causing 2-bit failure are extracted (S 1/S2) and a third factor for simultaneously causing the 1-bit and 2-bit failures is extracted (S3). Further, a ratio (k) of the occurrence frequency of 1-bit failure and that of 2-bit failure is calculated (S4). Then, the occurrence probability of 1-bit failure and 2-bit failure obtained from the measurement result of a random access memory is plotted on X-Y coordinates. When the plot point changes in the direction which is parallel to X axis, it is determined that a main cause is only the first factor. When the plot point changes in the direction which is vertical to X axis, it is determined that the main cause is the second factor. Then, when the plot point changes in the direction formed by an angle tan<-1>k, it is determined that the main cause is the third factor. |
