Highly Reliable and Magnetic-Field-Immune Physically Unclonable Functions Using One-Time Programming in SOT-MRAM Arrays

Spin–orbit torque magnetic random-access memory (SOT-MRAM) is a promising nonvolatile memory technology, offering low power consumption and high-speed read/write performance. The inherent fabrication variations within SOT units generate static entropy, making them suitable as carriers of physically unclonable functions (PUFs). Integrating PUFs with SOT-MRAM chips enhances hardware security and improves the fabrication feasibility, area efficiency, and cost-effectiveness. In this work, we present a highly reliable SOT-MRAM-based PUF design, where the introduction of one-time programmable significantly enhances PUF reliability, such as a 44× improvement in read margin, an optimal inter/intra-Hamming distance ratio, and zero bit error rate. Furthermore, the proposed OTP-PUF exhibits exceptional resilience to external magnetic fields (up to 500 Oe) and stable readout across an extended temperature range (−55 °C–150 °C), guaranteeing reliability in harsh environments. The results demonstrate that SOT-MRAM-based OTP-PUF presents a promising solution for secure memory systems.