Hardware implementation of physically unclonable function (puf) in perpendicular STT MRAM

The pSTT MRAM array with stepped structure MTJ is fully integrated with standard 0.18 μm CMOS process. Using a low power etch process greatly improves the uniformity of MR and R
_P
. The bit pattern is randomized with a voltage method and a cost-effective field method; the latter can be incorporated into wafer processing. We showed the bit pattern is unpredictable under the same sub-critical stimulation, thus, practically unclonable. The Hamming Weight and inter-chip Hamming Distance are both ~50%, an evidence of sufficient uniqueness. A single embedded STT-MRAM PUF can cover many needs of security electronics.