A New Direct Evaluation Method to Obtain the Data Retention Time Distribution of DRAM

The authors have developed an efficient and accurate method to obtain the data retention time distribution of DRAM from the physics-based device simulation and the numerical integration of the probability space composed of three independent random variables, namely 1) the number, 2) the location, and 3) the energy level of traps, where each trap acts as a localized leakage source. Compared with the recently proposed Monte Carlo method, this method is much more efficient and free from the statistical error in the tail distribution. Furthermore, it can be easily applied to the problem involving a complex geometry and the nonuniform spatial distribution of traps. With this method, the retention time distribution of an 80-nm technology DRAM with the recess-channel-array transistor is studied