Characterization, Modeling and Test of Synthetic Anti-Ferromagnet Flip Defect in STT-MRAMs

Lizhou Wu, Siddharth Rao, Mottaqiallah Taouil, Erik Jan Marinissen, Gouri Sankar Kar, Said Hamdioui

Research output: Chapter in Book/Conference proceedings/Edited volumeConference contributionScientificpeer-review

7 Citations (Scopus)
122 Downloads (Pure)


Understanding the manufacturing defects in magnetic tunnel junctions (MTJs), which are the data-storing elements in STT-MRAMs, and their resultant faulty behaviors are crucial for developing high-quality test solutions. This paper introduces a new type of MTJ defect: synthetic anti-ferromagnet flip (SAFF) defect, wherein the magnetization in both the hard layer and reference layer of MTJ devices undergoes an unintended flip to the opposite direction. Both magnetic and electrical measurement data of SAFF defect in fabricated MTJ devices is presented; it shows that such a defect reverses the polarity of stray field at the free layer of MTJ, while it has no electrical impact on the single isolated device. The paper also demonstrates that using the conventional fault modeling and test approach fails to appropriately model and test such a defect. Therefore device-Aware fault modeling and test approach is used. It first physically models the defect and incorporate it into a Verilog-A MTJ compact model, which is afterwards calibrated with silicon data. The model is thereafter used for fault analysis and modeling within an STT-MRAM array; simulation results show that a SAFF defect may lead to an intermittent Passive Neighborhood Pattern Sensitive Fault (PNPSF1i) when all neighboring cells are in logic '1' state. Finally, test solutions for such fault are discussed.

Original languageEnglish
Title of host publication2020 IEEE International Test Conference, ITC 2020
Number of pages10
ISBN (Electronic)978-1-7281-9113-3
ISBN (Print)978-1-7281-9114-0
Publication statusPublished - 2021
EventIEEE International Test Conference - Washington DC, United States
Duration: 3 Nov 20205 Nov 2020

Publication series

NameProceedings - International Test Conference
ISSN (Print)1089-3539


ConferenceIEEE International Test Conference
Abbreviated titleITC
Country/TerritoryUnited States
CityWashington DC
Internet address


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