Individual cell measuring method for FeRAM retention testing

We propose a new testing methodology to predict the failure rate for long-term data retention of FeRAM chips. The individual retention time limit for each memory cell is determined by measuring the retention time dependence on the read signal voltage using a novel test system. From this experiment, we found that the retention time limit of each memory cell obeys a Gaussian distribution. We applied this method to the evaluation of 16 kbit FeRAM test chips, and successfully predicted the failure rates for long-term data retention time as the functions of temperature and writing voltage.