A physical model to predict STT-MRAM performance degradation induced by TDDB

STT-MRAM is one of the most promising candidates as a next generation nonvolatile memory due to its high speed, low power consumption and superior scalability. While much insight on device physics of MTJ has been gained in recent years, understanding of the impact of TDDB on STT-MRAM performance has been rather limited. In particular, for continuously improving the performance of MTJ, scaling of oxide thickness and increasing voltage drop across MTJ (Vmϋ) are the two main solutions which can degrade the reliability margin. Therefore, an accurate TDDB reliability model with sound underlying physics is needed for evaluation of post-BD reliability of STT-MRAM. In this work, a physical model that captures the random nature of oxide BD time and post-BD current is proposed. Base on the simulation results (validated with experimental results), we suggest new design constraints for better reliability of STT-MRAM.