A new method for predicting distribution of DRAM retention time

A new method for predicting the distribution of retention time of a dynamic random access memory (DRAM) by using the test element group (TEG) has been developed. The TEG is constructed of memory cells which are connected in parallel, so that the sum of memory-cell leakage currents can be measured. We verified that the t/sub ret/ main distribution can be statistically predicted from the distribution of TEG leakage current. Furthermore, we determined the measurement condition for detecting some TEGs that contain anomalously leaky cells, which limit the DRAM refreshing interval.