Comprehensive study on prediction of endurance properties from breakdown voltage in high-reliable STT-MRAM

We have comprehensively studied prediction of endurance properties STT-MRAM based on breakdown voltage. First, by using 8Mb test MRAM chip, we clarified that a scale parameter dominating the endurance properties can be well predicted from breakdown voltage (BV) by taking into account a field acceleration parameter. We have also clarified that the field acceleration parameter can be determined by dependence of BV on a voltage sweep rate. Those results indicate that the BV measurements can be used to predict the endurance properties. Based on the results for 8Mb test chip, we have fabricated 44Mb STT-MRAM for buffer memory usage in CMOS image sensor and verified high enough endurance greater than 10 ¹⁰ cycles.