A 40nm 4Mb High-Reliability STT-MRAM Achieving 18ns Write-Time and 94.9% Wafer-Level-Die-Yield Across -55°C-to-125°C

STT-MRAM emerges as one of the promising candidates for next-generation non-volatile memory, offering versatility across diverse applications [1]-[6]. However, designing high-reliability MRAM for automotive and aerospace applications is particularly challenging. It demands operation across wide temperature ranges while balancing retention, write speed, and endurance in extreme environments [7]. It remains a great challenge for wide-temperature design of reliable STT-MRAM operating from -55°C to 125°C with high wafer-level die yield: (1) Operations in MRAM chip necessitate multiple input voltages that are sensitive to temperature and process variations. Despite this critical requirement, a thorough analysis of on-chip power delivery architectures has been largely overlooked in prior MRAM designs. (2) Wide-temperature MRAM encounters breakdown and endurance degradation at low temperature, significantly affecting its reliability and suitability in extreme environments [8]. (3) Traditional MRAM yield analysis, primarily based on single-device tests or MT J arrays, inadequately considers die-to-die variations, circuit-system interactions, and real-world operating conditions, leading to statistically insignificant results.