Novel Magnetic Burn-In for Retention Testing of STTRAM

Mohammad Nasim Imtiaz Khana, Anirudh S. Iyengarb and Swaroop Ghoshc
School of Electrical Engineering and Computer Science, Pennsylvania State University, University Park, PA-16801, USA.


Spin-Transfer Torque RAM (STTRAM) is an emerging Non-Volatile Memory (NVM) technology that has drawn significant attention due to complete elimination of bitcell leakage. However, it brings new challenges in characterizing the retention time of the array during test. Significant shift of retention time under static (process variation (PV)) and dynamic (voltage, temperature fluctuation) variability furthers this issue. In this paper, we propose a novel magnetic burn-in (MBI) test which can be implemented with minimal changes in the existing test flow to enable STTRAM retention testing at short test time. The magnetic burn-in is also combined with thermal burn-in (MBI+BI) for further compression of retention and test time. Simulation results indicate MBI with 220Oe (at 25C) can improve the test time by 3.71 38 215;1013 X while MBI+BI with 220Oe at 125C can improve the test time by 1.97 38 215;1014X.

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